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Cadence, power, and muscle activation in cycle ergometry

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Abstract

Based on the resistance-rpm relationship for cycling, which is not unlike the force-velocity relationship of muscle, it is hypothesized that the cadence which requires the minimal muscle activation will be progressively higher as power output increases. To test this hypothesis, subjects were instrumented with surface electrodes placed over seven muscles that were considered to be important during cycling. Measurements were made while subjects cycled at 100, 200, 300, and 400 W at each cadence: 50, 60, 80, 100, and 120 rpm. These power outputs represented effort which was up to 32% of peak power output for these subjects. When all seven muscles were averaged together, there was a proportional increase in EMG amplitude each cadence as power increased. A second-order polynomial equation fit the EMG:cadence results very well (r2 = 0.87- 0.996) for each power output. Optimal cadence (cadence with lowest amplitude of EMG for a given power output) increased with increases in power output: 57 +/- 3.1, 70 +/- 3.7, 86 +/- 7.6, and 99 +/- 4.0 rpm for 100, 200, 300, and 400 W, respectively. The results confirm that the level of muscle activation varies with cadence at a given power output. The minimum EMG amplitude occurs at a progressively higher cadence as power output increases. These results have implications for the sense of effort and preferential use of higher cadences as power output is increased.

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... Hansen et al. (2021) claimed self-chosen cadence to depend on the preceding cadence, such as a previous trial. To complicate matters further, both optimal and preferred cadences increase with rising power outputs (Ansley and Cangley 2009;Coast and Welch 1985;MacIntosh et al. 2000). The different cadences, whether self-selected or imposed, present different cycling efficiencies (Ansley and Cangley 2009;Coast and Welch 1985;Driss and Vandewalle 2013;Francescato et al. 1995;Foss and Hallén 2004;MacIntosh et al. 2000), as well as different maximal power outputs (e.g., Beneke and Leithäuser 2017). ...
... To complicate matters further, both optimal and preferred cadences increase with rising power outputs (Ansley and Cangley 2009;Coast and Welch 1985;MacIntosh et al. 2000). The different cadences, whether self-selected or imposed, present different cycling efficiencies (Ansley and Cangley 2009;Coast and Welch 1985;Driss and Vandewalle 2013;Francescato et al. 1995;Foss and Hallén 2004;MacIntosh et al. 2000), as well as different maximal power outputs (e.g., Beneke and Leithäuser 2017). Consequently, non-optimal cadences will always result in lower power outputs, relative to metabolic cost, than could otherwise be produced (see also the distinction between most efficient and most powerful cadences, discussed later under 'Which Optimum?'). ...
... B Calculated internal work (mainly due to leg-mass acceleration-deceleration at increasing cadences) is near zero at the two lowest cadences but grows exponentially greater thereafter Fig. 11 The dropping efficiency of increasing cadence at a fixed power output (235 W), measured at 60, 80, and 100 rpm in 45 cyclists (Sanderson 1991). The drop in efficiency from 80 to 100 rpm is 18.0%, while to the extrapolated 120 and 140 rpm (blue markers) the respective drops are 33.7 and 50.3% and self-selected cadences increase with increasing power outputs (e.g., Ansley and Cangley 2009;Coast and Welch 1985;Dekerle et al. 2003;MacIntosh et al. 2000;Rudsits et al. 2018). The rising cadence makes muscle coordination increasingly more difficult to achieve and is another source of energy loss, particularly so with non-cyclists. ...
Article
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The elegant concept of a hyperbolic relationship between power, velocity, or torque and time to exhaustion has rightfully captivated the imagination and inspired extensive research for over half a century. Theoretically, the relationship’s asymptote along the time axis (critical power, velocity, or torque) indicates the exercise intensity that could be maintained for extended durations, or the “heavy–severe exercise boundary”. Much more than a critical mass of the extensive accumulated evidence, however, has persistently shown the determined intensity of critical power and its variants as being too high to maintain for extended periods. The extensive scientific research devoted to the topic has almost exclusively centered around its relationships with various endurance parameters and performances, as well as the identification of procedural problems and how to mitigate them. The prevalent underlying premise has been that the observed discrepancies are mainly due to experimental ‘noise’ and procedural inconsistencies. Consequently, little or no effort has been directed at other perspectives such as trying to elucidate physiological reasons that possibly underly and account for those discrepancies. This review, therefore, will attempt to offer a new such perspective and point out the discrepancies’ likely root causes.
... There is a well-documented link between the rate of force development and muscle activation. During voluntary contractions to a set force, but with an increasing rate of force development, whole muscle activation measured by integrated electromyography (EMG) increases with the increase in force rate (Bigland and Lippold 1954;Sale 1987;MacIntosh et al. 1999;Farina et al. 2004). While some discrepancies on this topic exist (Nelson et al. 1973;Barnes Communicated by Olivier Seynnes. ...
... While some discrepancies on this topic exist (Nelson et al. 1973;Barnes Communicated by Olivier Seynnes. 1980;Komi 1973;MacIntosh et al. 1999), they can mainly be explained by how force or rate was controlled. Accounting for these methodological discrepancies, findings consistently demonstrate that voluntary control of muscle activation must be adjusted to meet the changing mechanical demands of the task. ...
... Therefore, added neural drive during rapid force development is a likely requirement during many daily activities, to compensate for the decline in force-generating capacity induced by even greater fascicle shortening velocities compared to the velocities observed in our experiment. This is supported by the large changes in recruitment threshold with increasing contraction velocities in studies that investigated relatively slow versus very fast movements (Budingen and Freund 1976;Desmedt and Godaux 1977a) as well as by the increases in amplitude of surface EMG recordings, which further suggests additional motor unit recruitment (Bigland and Lippold 1954;Sale 1987;MacIntosh et al. 1999;Farina et al. 2004). ...
Article
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When rate of force development is increased, neural drive increases. There is presently no accepted explanation for this effect. We propose and experimentally test the theory that a small increase in rate of force development increases medial gastrocnemius fascicle shortening velocity, reducing the muscle’s force-generating capacity, leading to active motor units being recruited at lower forces and with increased discharge frequencies. Participants produced plantar flexion torques at three different rates of force development (slow: 2% MVC/s, medium: 10% MVC/s, fast: 20% MVC/s). Ultrasound imaging showed that increased rate of force development was related to higher fascicle shortening velocity (0.4 ± 0.2 mm/s, 2.0 ± 0.9 mm/s, 4.1 ± 1.9 mm/s in slow, medium, fast, respectively). In separate experiments, medial gastrocnemius motor unit recruitment thresholds and discharge frequencies were measured using fine-wire electromyography (EMG), together with surface EMG. Recruitment thresholds were lower in the fast (12.8 ± 9.2% MVC) and medium (14.5 ± 9.9% MVC) conditions compared to the slow (18.2 ± 8.9% MVC) condition. The initial discharge frequency was lower in the slow (5.8 ± 3.1 Hz) than the fast (6.7 ± 1.4 Hz), but not than the medium (6.4 ± 2.4 Hz) condition. The surface EMG was greater in the fast (mean RMS: 0.029 ± 0.017 mV) compared to the slow condition (0.019 ± 0.013 mV). We propose that the increase in muscle fascicle shortening velocity reduces the force-generating capacity of the muscle, therefore requiring greater neural drive to generate the same forces.
... Assessment of muscle activation in cycling has been mostly done using surface electromyography. This enables the measurement of varying effects in muscle recruitment, linked workload level [104], pedaling cadence [51,53], body position on the bicycle [105], fatigue state [52,106,107], and others. Combined use of surface EMG in laboratorial performance assessments (e.g., graded cycling tests) can enable the definition of metabolic-related intensities [108], which are useful in training prescription. ...
... Surface EMG has been used to monitor responses from muscle activation due to changes in workload [62,104], pedaling cadence [53,115], body position on the bicycle [105,116], fatigue state [52], and cycling skill [31,53]. At steady-state From a qualitative perspective, lower limb muscles are activated and deactivated in a given section of crank cycle. ...
... Muscle force-velocity relationship also naturally links force capability to muscle shortening velocity and both depend on pedaling cadence. In line with that pedaling cadence that minimizes muscle activation increases with greater power output [104]. The reason for that is also partially explained by greater contribution from inertial forces to crank torque at higher pedaling cadence, which can reduce muscle force requirements [119]. ...
Chapter
Improving the interaction between cyclists and their bicycles is a key issue to enhance performance. The reason for that is linked to the optimal use of force applied from cyclists at the pedals, handlebars and saddle in order to improve bicycle speed at the minimum possible energy cost.
... The result of the lower cadence during the cognitive task could be explained by the assumption that the mental rotation task might stabilize cadence by serving as a distraction, while our control condition might subjectively be too boring and subsequently lead to increased cadence. While there is a linear relationship between power output and effort measured as heart rate or oxygen uptake (Arts & Kuipers, 1994), there is evidence that this relationship is modulated by pedal cadence (Coast & Welch, 1985;Faria et al., 2005a;MacIntosh et al., 2000). The optimal cadence, i.e. the cadence which produces the lowest effort at a given power output, increases linearly with power output (Coast & Welch, 1985;MacIntosh et al., 2000) but might also be higher for trained cyclists (Faria et al., 2005a). ...
... While there is a linear relationship between power output and effort measured as heart rate or oxygen uptake (Arts & Kuipers, 1994), there is evidence that this relationship is modulated by pedal cadence (Coast & Welch, 1985;Faria et al., 2005a;MacIntosh et al., 2000). The optimal cadence, i.e. the cadence which produces the lowest effort at a given power output, increases linearly with power output (Coast & Welch, 1985;MacIntosh et al., 2000) but might also be higher for trained cyclists (Faria et al., 2005a). Both higher and lower ...
... However, without instruction or sufficient experience, people may be unable to ascertain their optimal pedal cadence and instead choose a higher than optimal cadence. Research from Coast and Welch (1985) and MacIntosh et al. (2000) suggests that cadences of 70 rpm, as adopted on average in our ME condition, become optimal at around 250 W. As 250 W is larger than any power implemented in our experimental conditions, this suggests higher than optimal cadence in both E and ME conditions. Because cadence was even higher in the E condition, one would expect even higher effort, both objectively and subjectively. ...
Article
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While the effects of aerobic exercise during a cognitive task on the performance of said cognitive task have been extensively studied, it has not been investigated whether cognitive performance during aerobic exercise influences the physical performance. For this, it is the main goal of the study to investigate the physical and cognitive performance during a simultaneous conduction of aerobic exercise and mental rotation. Forty-one German sport students cycled at 60% intensity while simultaneously performing a mental rotation task. In a within-subject design, both physical and cognitive performances were compared with isolated cycling and mental rotation as control conditions using both objective (heart rate and pedal cadence in the cycling task, reaction time and accuracy in the mental rotation task) and subjective (RPE) cognitive and physical measures. The results analyzed with hierarchical linear modeling revealed no effect of either simultaneous cognitive tasks on objective (heart rate) or subjective (RPE) physical effort, nor of simultaneous exercise on reaction time or accuracy in cognitive performance. However, we have found lower cadence during cognitive tasks, which was also stable in time compared to an increase in cadence during exercise control. Furthermore, our results demonstrated increased cognitive effort during exercise. Our findings suggest that increased effort, both physiological and cognitive, is required during combined physical and cognitive work in support of neurological resource conflicts caused by the differing demands of exercise and executive function.
... Assessment of muscle activation in cycling has been mostly done using surface electromyography. This enables the measurement of varying effects in muscle recruitment, linked workload level [104], pedaling cadence [51,53], body position on the bicycle [105], fatigue state [52,106,107], and others. Combined use of surface EMG in laboratorial performance assessments (e.g., graded cycling tests) can enable the definition of metabolic-related intensities [108], which are useful in training prescription. ...
... Surface EMG has been used to monitor responses from muscle activation due to changes in workload [62,104], pedaling cadence [53,115], body position on the bicycle [105,116], fatigue state [52], and cycling skill [31,53]. At steady-state From a qualitative perspective, lower limb muscles are activated and deactivated in a given section of crank cycle. ...
... Muscle force-velocity relationship also naturally links force capability to muscle shortening velocity and both depend on pedaling cadence. In line with that pedaling cadence that minimizes muscle activation increases with greater power output [104]. The reason for that is also partially explained by greater contribution from inertial forces to crank torque at higher pedaling cadence, which can reduce muscle force requirements [119]. ...
Chapter
Motion analysis involves detecting the position of joints and segments in a global coordinate system, which enables the assessment of translations and rotations. Exclusive analysis of motion does not take into account forces acting on the body and interactions to varying systems (e.g., bicycle components). In biomechanics, the most common approach for motion analysis is by filming subjects performing a given motion and tracking segments and joints throughout various frames. For that purpose, reference markers are attached to the skin at anatomical sites related to joint coordinate systems. Tracking these markers throughout motion is important to assess changes in segment and joint motion during a given task.
... For these reasons, the EMG-based cost functions, computed as the sum or weighted sum of the EMG signals of several muscles, have been used to assess the cost of cycling. EMG-based cost functions have been used, for example, to identify the optimal cadence at a given power output [70,71] or the optimal power output at which the standing position should be adopted [44]. By dividing the power-output by the cost-function a measure similar in essence to mechanical efficiency can also be attained [46,71]. ...
... More precisely, it is lower for individuals with a high percentage of slow-twitch fibers [86]. It is also important to note that (1) the cadence that maximizes the crank power output increases with the intensity of the muscle contraction, which is likely due to the orderly recruitment of the motor units [70], and (2) that in terms of energy consumption (i.e., gross efficiency) the optimal cadence is typically lower than 100 RPM (i.e., 60-70 RPM) [86]. The increase in muscle contraction velocity when increasing cadence also reduces the duration of the cycles, so that they reach less than 600 ms above 100 RPM. ...
Article
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State-of-the-art biomechanical laboratories provide a range of tools that allow precise measurements of kinematic, kinetic, motor and physiologic characteristics. Force sensors, motion capture devices and electromyographic recording measure the forces exerted at the pedal, saddle, and handlebar and the joint torques created by muscle activity. These techniques make it possible to obtain a detailed biomechanical analysis of cycling movements. However, despite the reasonable accuracy of such measures, cycling performance remains difficult to fully explain. There is an increasing demand by professionals and amateurs for various biomechanical assessment services. Most of the difficulties in understanding the link between biomechanics and performance arise because of the constraints imposed by the bicycle, human physiology and musculo-skeletal system. Recent studies have also pointed out the importance of evaluating not only output parameters, such as power output, but also intrinsic factors, such as the cyclist coordination. In this narrative review, we present various techniques allowing the assessment of a cyclist at a biomechanical level, together with elements of interpretation, and we show that it is not easy to determine whether a certain technique is optimal or not.
... Additionally, muscle activations have been proposed as criteria associated with pedaling optimization (Hug &Dorel, 2009). MacIntosh, Neptune, andHorton (2000) proposed an estimate of general muscle activity as the mean activation of seven lower limb muscles, and reported that this cost function was the lowest at the cadence preferred by the participants in various crank power conditions. Others studies showed that the pedaling posture affects the EMG patterns of the lower limb muscles in pedaling (Duc, Bertucei, Pernin, & Grappe, 2008;, but none investigated the relationship between an Electromyographic Cost Function (ECF) and the spontaneous seat-stand transition cycling with increasing crank power. ...
... When necessary, electrical noise components were removed using notch filters (generally between 50 and 400 Hz; band width = ± 0.3 Hz). The Electromyographic Cost Function (ECF) was defined as (MacIntosh et al., 2000): ...
Article
Spontaneous changes of movement patterns may allow to elucidate which criteria influence movement pattern preferences. However, the factors explaining the sit-stand transition in cycling are unclear. This study investigated if biomechanical and/or muscle activation cost functions could predict the power at which the spontaneous sit-stand transition occurs. Twenty-five participants performed an incremental test leading to the sit-to-stand transition, and subsequent randomized pedaling trials at 20 to 120% of the transition power in seated and standing position. A Moment Cost Function based on lower limbs net joint moments and two Electromyographic Cost Functions based on EMG data were defined. All cost functions increased with increasing crank power (p < 0.001) but at different rates in the seated and standing positions. They had lower values in the seated position below the transition power and lower values in the standing position above the transition power (p < 0.05). These results suggest that spontaneous change of position observed in cycling with increasing crank power represents an optimal choice to minimize muscular efforts. These results support the use of simple cost functions to define optimal settings in cycling and to assess the cost of cycling during short-term efforts.
... 8,9 The mechanical demand on lower limb musculature during stationary cycling could be manipulated by changing the crank workload and/ or cadence. [12][13][14][15] With systematic increases in crank workload and cadence during cycling, increases are observed in the lower extremity muscles' electromyography activity [13][14][15] and net joint powers at the ankle, knee, and hip. 12 During rehabilitation, individuals with knee OA may pedal at different workloads and cadences; nevertheless, the effects of these variables on interlimb symmetry in crank power output are not known. ...
... 8,9 The mechanical demand on lower limb musculature during stationary cycling could be manipulated by changing the crank workload and/ or cadence. [12][13][14][15] With systematic increases in crank workload and cadence during cycling, increases are observed in the lower extremity muscles' electromyography activity [13][14][15] and net joint powers at the ankle, knee, and hip. 12 During rehabilitation, individuals with knee OA may pedal at different workloads and cadences; nevertheless, the effects of these variables on interlimb symmetry in crank power output are not known. ...
Article
Cycling is commonly prescribed for physical rehabilitation of individuals with knee osteoarthritis (OA). Despite the known therapeutic benefits, no research has examined interlimb symmetry of power output during cycling in these individuals. We investigated the effects of external workload and cadence on interlimb symmetry of crank power output in individuals with knee OA versus healthy controls. Twelve older participants with knee OA and 12 healthy sex- and age-matched controls were recruited. Participants performed 2-minute bouts of stationary cycling at four workload-cadence conditions (75 W-60 rpm, 75 W-90 rpm, 100 W-60 rpm, and 100 W-90 rpm). Power output contribution of each limb towards total crank power output was computed over 60 crank cycles from the effective component of pedal force, which was perpendicular to the crank arm. Across the workload-cadence conditions, knee OA group generated significantly higher power output with their severely affected leg compared to the less affected leg (10% difference; p = .019). Healthy controls did not show interlimb asymmetry in power output (0.1% difference; p = 1.00). For both groups, interlimb asymmetry was unaffected by external workload and cadence. Our results indicate individuals with knee OA demonstrate interlimb asymmetry in crank power output during stationary cycling.
... the same vein, Poirier et al. (2007) showed that a moment cost function (MCF, Gonzalez and Hull, 1989) based on the sum of the lower limb joint torques was lower in a spontaneously chosen position at any given power output, except those very close to the power output at which the transition was made. MacIntosh et al. (2000) proposed that the averaged EMG activity of several muscles may also represent the mechanical cost of the lower limbs. Along the same lines, Turpin et al. (2016) showed that the integrated EMG signals of the lower limb muscles in the standing position were less than or equal to those in the seated position at high power outputs (i.e., >500 W), which suggests a lower ''EMG cost" in the standing position at these power outputs. ...
... ). The EMG Cost Function (ECF) was defined as(MacIntosh et al., 2000): ...
Article
When a high power output is required in cycling, a spontaneous transition by the cyclist from a seated to a standing position generally occurs. In this study, by varying the cadence and cyclist bodyweight, we tested whether the transition is better explained by the greater power economy of a standing position or by the emergence of mechanical constraints that force cyclists to stand. Ten males participated in five experimental sessions corresponding to different bodyweights (80%, 100%, or 120%) and cadences (50RPM, 70RPM, or 90RPM). In each session, we first determined the seat-to-stand transition power (SSTP) in an incremental test. The participants then cycled at 20%, 40%, 60%, 80%, 100%, or 120% of the SSTP in the seated and standing positions, for which we recorded the saddle forces and electromyogram (EMG) signals of eight lower limb muscles. We estimated the cycling cost using an EMG cost function (ECF) and the minimal saddle forces in the seated position as an indicator of the mechanical constraints. Our results show the SSTP to vary with respect to both cadence and bodyweight. The ECF was lower in the standing position above the SSTP value (i.e., at 120%) in all experimental sessions. The minimal saddle forces varied significantly with respect to both cadence and bodyweight. These results suggest that optimization of the muscular cost function, rather than mechanical constraints, explain the seat-to-stand transition in cycling.
... From Eq. (1) it is determined that, for a given power, there would be a series of cadence-pair combinations with which an individual could reach the desired output power. However, it is unlikely that the level of muscle activation will be able to reach the target power with all possible cadence-pair combinations due to the intrinsic muscle force-velocity relationship [8]. The relationship between speed and muscular strength allows establishing the maximum power output conditions of an individual in a pedaling mechanism [9]. ...
... The magnitude of this power is affected by the pedaling rate [28]. The cadence-pair relationship allows predicting the cadence that minimizes muscle activation at a given power output [8]. This relationship, for certain cadences, has a linear behavior [29]. ...
Article
Pedal energy a clean and sustainable alternative. • Energy harvesters allows the self-sourcing of an exercise bicycle. • The main elements of a pedaling energy harvester are identified. • Transmission and transformation of pedal energy to electrical energy are revised. • A sequence to design a pedaling energy harvester is proposed. A R T I C L E I N F O Keywords: Alternative energy Pedal energy Human energy Energy harvesting Transducer Energy transmission A B S T R A C T Pedaling energy is a clean and sustainable energy source capable of supplying power to a variety of low power electronic devices. Furthermore, pedaling energy has proven to be a sustainable energy solution, in combination with other renewable energy sources for developing communities. However, currently, the use of this energy is still limited. The main contribution of this paper is to present a review of static pedaling technologies that use rotary transducers to convert pedaling energy into electrical energy, to identify current advances and design trends, comparing and classifying the elements that integrate the main stages of energy transmission and transformation, identifying areas of opportunity to improve their functionality, efficiency or other aspects of interest. The review includes information about the human capacity to deliver power in a pedaling mechanism such as the cadence-power ratio, cadence-torque, maximum power, and critical power. As a result of the review are reported geometric structure, transducer type, power converter, transmission ratio, power output, among other of the reviewed systems data. Moreover, a design sequence, which is considered appropriate, is proposed to optimize the pedaling energy harvesters of static mechanisms. Finally, the review results, trends, and challenges are discussed.
... Yürüyüş kinetik, kinematik ve temporal verilere sahiptir. Temporal verilerden birisi olan kadans, yürüyüşü kişiye özel hale getiren kimliksel bir parametredir (12). Kadansın ayarlanması mezensefalon veya spinal düzeydeki lokomotor bölgeler tarafından düzenlenmektedir (13). ...
... Fakat diğer veriler karşılaştırıldığında brain ve ark. elde ettiği veriler yüksektir (12). Ata ve ark. ...
Article
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Purpose: Cadence is a value that can vary from person to person and is usually calculated as the number of steps per minute. Baropedometer, on the other hand, provides detailed analysis of foot dynamics by measuring the pressure distribution under the foot. In addition to cadence, it is also used in the evaluation and measurement of foot diseases in clinics and studies. Methods: In our study, using 2014 model Diasu by Sani Corporate's baropedometer device; Separate cadence values (step/min) were calculated for the right and left feet. Demographic data such as age, weight and height of 101 individuals included in this study were recorded. The averages of the walks were taken into considerationfrom these recorded data. The obtained data were evaluated with Independent Samples Test in SPSS 25.0 package program. Result: Male right and left cadence values were 58,07±23,77 steps/min, 58,18±24,67 steps/min, respectively. while in female individuals, these values were 55,87±22,89 steps/min on the right; on the left 56,75±21,52 steps/min. As a result of the statistical analysis, no significant difference was found between cadence and measurement data (p>0.05). Conclusion: When the literature is examined, cadence examines the changes in disease and aging alongwith other gait parameters. The insignificance of cadence change in healthy individuals due to demographicinformation made us think that cadence can only change in healthy individuals when they are diagnosed with the disease. Considering the studies stating that the change in cadence depends on walking speed and stride distance, it was thought that these parameters of gait should also be evaluated in future studies. There are studies in the literature reporting that cadence increases with age. However, no study has been found in the literature that directly correlates sole pressure with cadence. We think that our study will be a guide for other studies that reveal the factors affecting cadence.
... The most complicated factor to consider may be exercise intensity. Indeed, it is well known that FCC is intensity-dependent [29] and that, for a given percentage of peak oxygen consumption, shifting from one cadence to another affects power output. Conse-quently, the conclusions from studies testing the effect of pedaling cadences based on different intensity criteria (e.g., given power output or oxygen uptake) should be compared with caution [29]. ...
... Indeed, it is well known that FCC is intensity-dependent [29] and that, for a given percentage of peak oxygen consumption, shifting from one cadence to another affects power output. Conse-quently, the conclusions from studies testing the effect of pedaling cadences based on different intensity criteria (e.g., given power output or oxygen uptake) should be compared with caution [29]. Moreover, the cadences considered as low or high are heterogeneous because some investigators chose absolute and other relative (e.g., ± 20% FCC) cadences below and above the preferred one [11,12]. ...
Article
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There is a wide range of cadence available to cyclists to produce power, yet they choose to pedal across a narrow one. While neuromuscular alterations during a pedaling bout at non-preferred cadences were previously reviewed, modifications subsequent to one fatiguing session or training intervention have not been focused on. We performed a systematic literature search of Pub-Med and Web of Science up to the end of 2020. Thirteen relevant articles were identified, among which eleven focused on fatigability and two on training intervention. Cadences were mainly defined as "low" and "high" compared with a range of freely chosen cadences for given power output. However, the heterogeneity of selected cadences, neuromuscular assessment methodology, and selected population makes the comparison between the studies complicated. Even though cycling at a high cadence and high intensity impaired more neuromuscular function and performance than low-cadence cycling, it remains unclear if cycling cadence plays a role in the onset of fatigue. Research concerning the effect of training at non-preferred cadences on neuromuscular adaptation allows us to encourage the use of various training stimuli but not to say whether a range of cadences favors subsequent neuromuscular performance.
... Dass der Trittfrequenz ein bedeutender Einfluss auf die radsportliche Leistung zugesprochen wird wurde bereits im Zusammenhang mit Effizienz und Ökonomie mehrfach erwähnt (Faria et al., 2005a(Faria et al., , 2005b. Auch deshalb ist die Quantifizierung der EMG-Aktivitätslevel bei unterschiedlichen Kadenzen und konstanter Leistung eine äußerst beliebte Problemstellung in sportwissenschaftlichen Forschungskreisen (Baum & Li, 2003;Blab, 2009;Ericson, 1986;Li & Baum, 2004;Lucia et al., 2004;MacIntosh, Neptune & Horton, 2000;Marsh & Martin, 1995;Neptune, Kautz & Hull, 1997;Sarre et al., 2003;Suzuki, Watanabe & Homma, 1982 (Cruz & Bankoff, 2001;Ericson, 1986). ...
... Die Resultate hinsichtlich Reproduzierbarkeit zwischen 0 1 % und 0 2 % sind konsistent mit den Ergebnissen weiterer Reliabilitätsstudien. Houtz und Fischer (1959) (Baum & Li, 2003;Blab, 2009;Edwards & Lippold, 1956;Ericson, 1986;Housh et al., 2000;Li & Baum, 2004;Lucia et al., 2004;MacIntosh et al., 2000;Marsh & Martin, 1995;Neptune et al., 1997;Petrofsky, 1979;Psek & Cafarelli, 1993;Sarre & Lepers, 2005;Sarre et al., 2003;Saunders et al., 2000;Suzuki et al., 1982). ...
Thesis
Ziel der Arbeit war es, das EMG-Innervationsverhalten von vier vortriebswirksamen Muskeln der unteren Extremität beim Radfahren in der Ebene sowie bei 10 %, 20 % und 30 % Steigung zu beschreiben und mit einer Fahrt in der Ebene zu vergleichen. In einem zweiten Schritt wurde im Rahmen einer Reliabilitätsuntersuchung geklärt, wie hoch die Schwankungsbreite zwischen zwei identischen Messungen in der Ebene ausfällt. Dreizehn Radfahrer der regionalen und nationalen Leistungsklasse absolvierten einen Test mit fünf verschiedenen Belastungsbedingungen (Ebene, 10 %, 20 %, 30 %, Ebene) und elektromyografischer Messung von vier Muskeln der unteren Extremität (M. rectus femoris = RF, M. vastus lateralis = VL, M. semitendinosus = ST, M. tibialis anterior = TA). Die Untersuchungen wurden bei einer Leistung von 90 % des maximalen Laktat-steady-states sowie bei einer von den Versuchspersonen selbst gewählten über alle Belastungsstufen hinweg konstanten Trittfrequenz durchgeführt. Als wesentliche Ergebnisse zeigten sich signifikante Veränderungen des muskulären Aktivitätslevel bei 10 % Steigung im Vergleich zur Ebene für ST (+16 %) und TA (-10 %). Bei 20 % Steigung (vs. Ebene) reduzierten RF und TA ihre Intensität um 13 % (RF; p ≤ 0,05) und 18 % (TA; p ≤ 0,05). Hinsichtlich ST war ein höheres Aktivitätslevel von 18 % (p ≤ 0,05) messbar. Alle untersuchten Muskeln veränderten ihre Intensität bei 30 % Steigung im Vergleich zur Ebene (RF = -12 % (p ≤ 0,05); VL = -11 % (p ≤ 0,05); ST = +27 % (p ≤ 0,05); TA = -20 % (p ≤ 0,05)). Zusätzlich nimmt die Summenaktivität aller Muskeln mit zunehmender Steigung in der zweiten Hälfte des Tretzyklus ab (10 %: p ≤ 0,05; 20 %: p ≤ 0,05). Der Vergleich zwischen den zwei Belastungen in der Ebene brachte keine nennenswerten EMG-Veränderungen mit sich. Die Ergebnisse offenbaren, dass durch die Neuorientierung des Oberkörpers Veränderungen im EMG-Innervationsverhalten bereits bei moderater Steigung auftreten. Diese Modifikationen sind bei schwerer (20 %) und sehr schwerer Steigung (30 %) am deutlichsten, wobei neben dem M. tibialis anterior die dem Hüftgelenk entspringenden Muskeln (RF und ST) am stärksten von Veränderungen betroffen sind. Bei sehr schwerer Steigung zeigt auch der Knieextensor M. vastus lateralis Anpassungen.
... Increased muscle force at high workloads could be produced by increasing muscle activation magnitude and contraction timing. [9][10][11][12] Interestingly, with the workload increase, VL's activation time decreased, while SO's muscle activation time increased. 13 Assuming that knee joint extensors act mostly concentrically during the crank cycle, increases in workload might determine a need for decreasing the knee extensors' concentric contribution with an increase in the eccentric's contraction time due to its reduced metabolic cost. 2 Also, although plantar flexor bi-articular muscles' (e.g., gastrocnemius) timing of contraction adapted to changes in saddle height, it is not known if this adaptation also occurs with a workload increase. ...
... Increased muscle force at high workloads could be produced by increasing muscle activation magnitude and contraction timing. [9][10][11][12] Interestingly, with the workload increase, VL's activation time decreased, while SO's muscle activation time increased. 13 Assuming that knee joint extensors act mostly concentrically during the crank cycle, increases in workload might determine a need for decreasing the knee extensors' concentric contribution with an increase in the eccentric's contraction time due to its reduced metabolic cost. 2 showing especial benefits from improvements in aerobic power/capacity, exercise tolerance, strength and muscle mass in clinical populations. ...
Article
Background: The mechanical energy required to drive the cranks during cycling depends on concentric and eccentric muscle actions. However, no study to date provided clear evidence on how workload levels affect concentric and eccentric muscle actions during cycling. Therefore, the aim of this study was to investigate the workload effects on the timing of lower limb concentric and eccentric muscle actions, and on joint power production. Methods: Twenty-one cyclists participated in the study. At the first session, maximal power output (POMAX) and power output at the first (POVT1) and second (POVT2) ventilatory thresholds were determined during an incremental cycling test. At the second session, cyclists performed three trials (2-min/each) in the workloads determined from their POMAX, POVT1 and POVT2, acquiring data of lower limb muscle activation, pedal forces and kinematics. Concentric and eccentric timings were computed from muscles' activations and muscle-tendon unit excursions along with hip, knee and ankle joints' power production. Results: Longer rectus femoris eccentric activation (62%), vastus medialis concentric (66%) and eccentric activation (26%) and biceps femoris concentric (29%) and eccentric (133%) activation at POMAX were observed compared to POVT1. Longer positive (12%) and shorter negative (12%) power were observed at the knee joint for POMAX compared to POVT1. Conclusions: We conclude that, to sustain higher workload levels, cyclists improved the timing of power transmission from the hip to the knee joint via rectus femoris eccentric, vastus medialis concentric and eccentric and biceps femoris concentric and eccentric contractions.
... Cependant, la durée relativement courte de l'exercice et l'unicité du muscle limitent la portée de cette étude. Des travaux ultérieurs ont cependant mis en évidence une minimisation de l'activité EMG des muscles impliqués dans le mouvement de pédalage pour des cadences proches de la CLC (MacIntosh et al. 2000, Vercruyssen et al. 2001. Les réponses musculaires aux changements de cadence semblent cependant dépendre fortement du type de muscle, en particulier de son caractère mono ou bi-articulaire (Sarre et al. 2003). ...
Article
Numerous studies have shown an alteration of neuromuscular function following prolonged cycling exercises (from 30 min to several hours). Muscular fatigue during this kind of exercises, evidenced by reduction of maximal power output during intense efforts such as sprint, is generally quantified by the loss of maximal voluntary force of the knee extensor muscles. Techniques of percutaneous stimulation of the femoral nerve allow to identify peripheral (Mwave, excitation-contraction coupling process, contractility) and central (activation level) mechanisms of fatigue. Central fatigue, locating at spinal and/or supraspinal level, seems to occur later than peripheral fatigue when exercise lasts several hours. Interestingly, recent studies tend to show that neuromuscular alterations do not depend on pedalling frequency. In fatigue conditions, pedalling pattern remains stable during sub-maximal exercise if exercise is not performed until exhaustion. Mechanisms such changes in muscular strategies, allowing the cyclist to sustain an identical intensity throughout long-duration exercise without degradation of locomotor pattern need further investigations.
... Possivelmente o aumento nas forças pode estar associado às mudanças na resistência de frenagem do ciclo ergômetro, quando programado para operar em carga constante, de acordo com alterações na cadência de pedalada (MACINTOSH et al., 2000). O aumento das forças seria explicado por uma estratégia muscular na tentativa de manter a potência constante, pois em baixas velocidades de encurtamento os músculos são capazes de gerar mais força (HILL, 1949 (ERICSON et al., 1988). ...
Thesis
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Muscle fatigue can be defined as an inability to sustain a determined level of force under a given intensity, which involves physiological, biomechanical and psychological factors. The purpose of this thesis was to investigate the effects of fatigue on biomechanical aspects of cycling. Two studies were designed to evaluate fatigue up to exhaustion. For the first study, the aims were to evaluate cadence, pedal forces and electrical activity of lower limbs muscles during a cycling trial until exhaustion. Fourteen triathletes completed an incremental maximal cycling test and in the following day pedaled up to exhaustion under a workload eliciting 100% of the maximal oxygen uptake. Data of cadence, pedal forces and electromyography (EMG) from gluteus maximus (GL), rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), gastrocnemius medialis (GM), tibialis anterior (TA) and soleous (SO) muscles were acquired during 10 s for the start, middle and end of the fatigue trial. The root mean square (RMS) value was used as an indicator of total muscle activation. Normal and tangential forces increased significantly from the start to the end of the test, whereas cadence statistically significantly decreased. The RMS value of GL, VL, RF and VL significantly increased from the start to the end of the test. Nevertheless, activation did not statistically change for BF, GM, TA and SO. The fatigue during cycling leaded to increases in GL and knee extensors activation, as well as in normal pedal force and to a decrease in cadence. The maintenance of the target workload appears to be related to higher participation of GL and VL. For the second study, the aim was to investigate the effects of fatigue on the pedaling technique. Eight elite cyclists completed an incremental maximal cycling test and completed a cycling test until exhaustion under workload eliciting 100% of the maximal oxygen uptake in the following day. During the test, instrumented pedals were used for evaluation of pedaling technique. Kinematic assessment was used to monitor the angular behavior of the ankle joint and of the pedal. The right lower limb resultant pedal force and effective force were computed for determination of the effectiveness index (IE). During the fatigue test, IE did not change significantly. The ankle kinematics revealed statistical increase for ankle and pedal ranges of motion with fatigue. These results suggest that muscle fatigue leads to changes in pedaling technique. The changes in ankle kinematics seems to support the IE maintenance during pedaling up to exhaustion, even so power producer muscles presented fatigue, as described in the first study. Data from both studies suggest that athletes change pedaling technique due to fatigue, but they are able to sustain patterns of muscle activation and kinematic in an attempt to prolong the time to exhaustion.
... Since diverse researchers have arrived at different conclusions, the impact of cadence on EMG values has also not been well explained yet. MacIntosh, Neptune, & Horton (2000) reported that inter-muscle activity relations change in accordance with the workload and cadence. The lowest values are found at higher cadences during larger workloads and vice versa. ...
... The exact mechanisms that influence cadence selection in endurance-trained cyclists are not yet fully understood. It has been proposed that cadence selection is linked to minimizing the muscular demands of the task as shown by reductions in T peak and T mean and changes in the crank torque profile (Patterson and Moreno 1990;MacIntosh et al. 2000;Bertucci et al. 2005). The hypothesis that the FCC would be closely associated with the need to minimize the muscular demands of the task was only partly supported. ...
Article
The aim of this study was to determine the effects of high- and low-cadence interval training on the freely chosen cadence (FCC) and performance in endurance-trained cyclists. Sixteen male endurance-trained cyclists completed a series of submaximal rides at 60% maximal power (Wmax) at cadences of 50, 70, 90, and 110 r·min(-1), and their FCC to determine their preferred cadence, gross efficiency (GE), rating of perceived exertion, and crank torque profile. Performance was measured via a 15-min time trial, which was preloaded with a cycle at 60% Wmax. Following the testing, the participants were randomly assigned to a high-cadence (HC) (20% above FCC) or a low-cadence (LC) (20% below FCC) group for 18 interval-based training sessions over 6 weeks. The HC group increased their FCC from 92 to 101 r·min(-1) after the intervention (p = 0.01), whereas the LC group remained unchanged (93 r·min(-1)). GE increased from 22.7% to 23.6% in the HC group at 90 r·min(-1) (p = 0.05), from 20.0% to 20.9% at 110 r·min(-1) (p = 0.05), and from 22.8% to 23.2% at their FCC. Both groups significantly increased their total distance and average power output following training, with the LC group recording a superior performance measure. There were minimal changes to the crank torque profile in both groups following training. This study demonstrated that the FCC can be altered with HC interval training and that the determinants of the optimal cycling cadence are multifactorial and not completely understood. Furthermore, LC interval training may significantly improve time-trial results of short duration as a result of an increase in strength development or possible neuromuscular adaptations.
... This divergence is more easily detected in the power data (Figure 1a). Interestingly, after approximately 10 s, cadence has decreased to values known to be more closely aligned to peak muscular power development (100-120 rev/min) (Dimitrova and Dimitrov 2013;Hautier et al. 1996;Katch et al. 1977;MacIntosh et al. 2000;MacIntosh et al 2003;Reiser et al. 2003;Samozino et al. 2007). As such, one could argue that all prior peak power measures from the TRAD are artificially high and caused by the excessively high cadence at the test onset. ...
Article
Full-text available
A Study Abstract. We hypothesized that the protocol-induced initial cadence of the WAnT is too high to allow high muscle force production and peak power generation. Twenty endurance, strength or power trained subjects (9 male, 11 female) completed two 30 s maximal exertion stationary cycle ergometer tests involving the traditional peak cadence start (TRAD) vs. a stationary start (STAT). Inertia corrected mechanical power, cadence, EMG from the vastus lateralis, and applied force to the pedals were measured continuously throughout both tests. Peak power was higher during TRAD; 11.32 ±1.41 vs. 10.40 ±1.35 Watts/kg (p < 0.0001), as was peak cadence; 171.4 ±16.3 vs. 120.9 ±15.1 rev/min (p < 0.0001). However, during TRAD EMG root mean squared (rms) increased continuously throughout the test, force applied to the pedals increased from 1 to 3 s (0.73 ±0.27 vs. 0.90 ±0.39 N/kg; p = 0.02) and thereafter remained relatively stable. EMG mean frequency also increased from 1 to 3 s, but then decreased throughout the remainder of the test. During TRAD, mechanical power decreased near immediately despite increasing EMG rms, EMGmean frequency and force application to the pedals. The initial 10 s of data from the WAnT is invalid. We recommend that intense cycle ergometer testing should commence with a stationary start.
... During the last years, skin temperature monitoring with infrared thermography have gained attention in running and cycling for analyzing the effect of exercise [32,9,37,45]. In cycling, exercise workload produces greater power output [18] with higher muscle activation [31] resulting in an increased core temperature [16]. However, it is unclear how it affects skin temperature. ...
Article
Purpose: The aim of the study was to determine the influence of cycling workload on the variation of core and skin temperature of the different body regions, and the relationship between both temperature variables. Method: Fourteen cyclists performed two 45-min cycling tests at 35% and 50% of peak power output on different days. The cadence was constant in both tests (90 rpm). Core temperature was measured continuously throughout the test and local skin temperature was recorded before, immediately after and 10 min after finishing the cycling test. Differences in variation of the core and skin temperature and in the effort perception and body mass loss due to different cycling workload were analyzed. Additionally, the relationship between core and skin temperature was assessed. Results: Core temperature of the test at 50% was between 0.2 and 0.3 °C higher than at workload of 35%. The tibialis anterior region, the ankle anterior region and the Achilles region presented higher reductions in skin temperature due to exercise for test at 50% than 35%, and knee presented a lower increase (p < 0.05). Core and skin temperatures showed either weak or moderate inverse correlation for most of the body regions, but in others such as knee, ankle anterior and Achilles region, a positive weak relationship was observed. Conclusions: The findings of the present study highlight the difficulty of linking skin temperature with cycling workload and core temperature due to the thermoregulatory system efficiency in the increase of the thermal gradient, alongside the multifactorial dependence of the skin temperature.
... As estratégias pelas quais o sistema nervoso central controla a cadência de pedalada têm sido investigadas por meio da análise da técnica de pedalada (Patterson e Moreno, 1990; Sanderson, 1991; Rossato et al., in press), ativação muscular (MacIntosh et al., 2000; Baum e Li, 2003) e cinemática articular (Sanderson et al., 2006). Evidências foram apresentadas indicando que a cadência preferida de pedalada seria um padrão motor robusto, determinado com o objetivo de minimizar a sobrecarga sobre o sistema músculo-esquelético (Hansen et al., 2008). ...
... it has also been reported that at a constant workload over a range of cadences (40-120 rpm), torque peak in cyclists decreased inversely with cadence. 60 Whitty et al. 61 confirmed these findings for net torque values at absolute power outputs (150 and 200 W) at varying cadences (50-110 rpm) in non-cyclist. Torque mean has also been shown found in the rSh group could be caused by aTp metabolic change that intermittent hypoxia produces in organisms. ...
Article
Full-text available
Background: This pilot study had the aim to determine the effects of a new dose of maximal-intensity interval training in hypoxia in active adults. Methods: Twenty-four university student volunteers were randomly assigned to three groups: hypoxia group, normoxia group or control group. The eight training sessions consisted of 2 sets of 5 repeated sprints of 10 seconds with a recovery of 20 seconds between sprints and a recovery period of 10 minutes between sets. Body composition was measured following standard procedures. A blood sample was taken for an immediate haematocrit and haemoglobin concentration assessment. An all-out 3-ute test was performed to evaluate ventilation parameters and power. Results: Haemoglobin and haematocrit were significantly higher for the hypoxia group in Post- and Det- (p=0.01; p=0.03). Fat mass percentage was significantly lower for the hypoxia group in both assessments (p=0.05; p=0.05). The hypoxia group underwent a significant increase in mean power after the recovery period. Conclusions: A new dose of 8 sessions of maximal-intensity interval training in hypoxia is enough to decrease the percentage of fat mass and to improve haemoglobin and haematocrit parameters and mean muscle power in healthy and active adults.
... Varying the pedaling frequency may affect iEMG differently in seated versus standing positions as it depends on the contraction velocity of each muscle. 29,30 Additionally, the spontaneously chosen cadence is generally lower in the standing position, 6 but we chose to use a fixed cadence to be able to compare EMGs under similar conditions. In field conditions other factors such as lateral bicycle oscillations or vibrations may also affect muscles activity and coordination. ...
Article
Full-text available
Objectives: When compared to seated, the standing position allows the production of higher power outputs during intense cycling. We hypothesized that muscle coordination could explain this advantage. To test this hypothesis, we assessed muscle activity over a wide range of power outputs for both seated and standing cycling positions. Design: Nine lower limb muscle activities from seventeen untrained volunteers were recorded during cycling sequences performed in the seated and the standing positions at power outputs ranging from ∼100 to 700W at 90±5 revolutions-per-minute (RPM). Methods: Integrated electromyography activity (iEMG), temporal patterns of the EMGs, and muscle synergies were analyzed. Results: Muscle activity was underlain by four muscle synergies in both positions. Muscle synergies were similar in the two positions (Pearson's r=0.929±0.125). The activation patterns of knee and ankle extensor muscles and their associated synergies had different timings in the two positions (differences of ∼2-10% of cycle). No major timing changes were observed with power output (<2% of cycle). Differences in iEMG between the two positions depended strongly on power output in all but the calf muscle (medial gastrocnemius). Conclusions: The number and structure of the muscle synergies play a minor role in the advantage of using the standing position when cycling at high power-outputs. However, the standing position is favorable in terms of iEMG at power outputs ≳500-600W due to position-dependent modulations of muscle activation levels. These data are important for understanding the determinants of the seat-stand transition in cycling.
... A number of studies demonstrated that the recruitment of typ II muscle fibres is enhanced with higher pedal rate for the same work rate (Beelen & Sargeant, 1993;MacIntosh et al., 2000;Sargeant, 1994Sargeant, , 1999. Furthermore, they reported that subjects tend to use higher pedal rates at heavy exercise compared to low work rates. ...
Thesis
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One of the most meaningful parameters for performance measurement in cycling are oxygen uptake kinetics and gross efficiency. A number of studies investigated efficiency and oxygen uptake during cycling in the laboratory. Therefore, the aim of this study was to analyse the effect of gradient, cadence and exercise intensity on oxygen uptake kinetics and gross efficiency (GE) in laboratory conditions and to verify previous results. Thirteen well-trained cyclists participated in this study (mean ± SD age: 23.0 ± 4.7 years; stature: 178.5 ± 5.2 cm; body mass: 69.0 ± 7.8 kg; V̇O2max: 68.2 ± 4.7 mL∙min-1∙kg-1). The study consisted of two testing sessions: one incremental graded exercise test (GXT) to exhaustion and on a separate day 8 test-trials of 6 min duration. To simulate gradient the test bike was mounted on an indoor training roller and fixed on a treadmill. The GXT was performed to determine maximum oxygen uptake (V̇O2max), maximum power output (Pmax) and gas exchange thresholds (VT and RCP). During the laboratory test the subjects performed 4 trials on level ground (1.5% inclination) and 4 uphill trials (5% inclination). The trials were performed at two intensities (90%VT and Δ70) and two cadences (60 and 90 rev.min-1). The order of the four level and uphill cycling trials was 90%VT at 60 rev.min-1, Δ70 at 60 rev.min-1, 90%VT at 90 rev.min-1, Δ70 at 90 rev.min-1. Significant differences between uphill and level ground cycling were found for the time constant (τ) (mean difference = 2.8 s; F1,12 = 5.1; p = 0.043) and end-exercise V̇O2 (mean difference = 69 mL.min-1; F1,12 = 6.3; p = 0.027) of the phase II oxygen uptake response. Cadence significantly affected the τ (mean difference = 3 s; F1,12 = 7.1; p = 0.021) and amplitude (mean difference = 176 mL.min-1; F1,12 = 14.8; p = 0.002). Significant differences between moderate and high exercise intensities were found for all measured oxygen uptake kinetics parameters (i.e. τ, amplitude, slow component, end-exercise V̇O2 gain, phase II V̇O2 gain and end-exercise V̇O2) except time delay. The GE was affected by cadence (21 ± 1.6 % at 60 rev.min-1; 18.6 ± 1.1 % at 90 rev.min-1; p < 0.001) but no significant effect of flat (19.7 ± 1.8 %) compared to uphill cycling (19.7 ± 1.8 %) was found (p = 0.81).
... R. P. Abbiss, Jeremiah J; Laursen, Paul B 2009). De igual forma, el pico máximo de fuerza que puede aplicarse sobre el pedal disminuye con el aumento de la cadencia (MacIntosh, Neptune, & Horton, 2000). Por este motivo, el momento de fuerza neto de la extremidad inferior disminuye a medida que se aumenta la cadencia de 50 a 95 rpm, e incluso a medida que se aumenta la potencia a desarrollar, la cadencia que minimiza este momento neto estaría entre los 90 a 110 rpm (Marsh, Martin, & Sanderson, 2000). ...
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RESUMEN. En el ciclismo de ruta de alto nivel, pequeños detalles pueden definir el resultado final. Además, el margen en las modificaciones que se pueden realizar en la configuración de la bicicleta a este nivel es muy estrecho. Hasta la fecha, en la literatura, se ha demostrado que cambios amplios en el reglaje de la bicicleta pueden afectar a la cadena cinética y a la eficiencia de pedaleo. Pero sin embargo, no queda claro, si pequeños ajustes de factores como la altura del sillín o la longitud de la biela, asumibles por ciclistas de alto nivel, realmente afectan a la biomecánica y la eficiencia de pedaleo. Para intentar dar respuesta a estas cuestiones, la presente Tesis Doctoral ha propuesto los siguientes objetivos, desarrollados a través de cuatro estudios: 1- comprobar si el ajuste de la altura del sillín a partir del método antropométrico asegura un pedaleo dentro del rango articular recomendado (método de goniometría dinámica), 2- comparar los métodos de goniometría estática y goniometría dinámica para ajustar la altura del sillín y analizar si las posibles diferencias entre métodos dependen de la altura relativa del sillín 3- evaluar si pequeños cambios de la altura del sillín afectan a la cinemática y a la eficiencia de pedaleo, 4- comprobar los efectos de pequeños cambios en la longitud de biela en la biomecánica y en la eficiencia de pedaleo. En el primer estudio en el que participaron 23 ciclistas de alto nivel del mismo equipo, se demostró que el método antropométrico (106-109% de la longitud de entrepierna) no asegura un ángulo de flexión de rodilla óptimo (30-40º) durante el pedaleo (método de goniometría dinámica). De hecho, más de la mitad de los ciclistas (56.5%) estaban fuera del rango antropométrico recomendado. Probablemente, esta discrepancia se debió a que la mayoría de estudios que predicen la altura relativa del sillín a partir de la longitud de la entrepierna utilizaron mayormente los pedales con rastrales en vez de los utilizados en la actualidad, principalmente pedales automáticos. Además, se propuso una ecuación novedosa (HS = 22.1 + (0.896 · LE) – (0.15 · AR)) que relaciona la longitud de la entrepierna (LE) con el ángulo de flexión de rodilla (AR) durante el pedaleo para ajustar una altura de sillín óptima (HS), utilizando pedales automáticos. En un segundo estudio, realizado con 13 ciclistas entrenados, se observó que el método de goniometría estática (25-35º de flexión de rodilla) subestimaba la flexión de rodilla (9-12º), la flexión de cadera (4-7º) y la flexión plantar del tobillo (7-13º). Además, se constató que las diferencias encontradas entre el método de goniometría estática y el método de goniometría dinámica son dependientes de la altura del sillín, fundamentalmente en las articulaciones de la rodilla y el tobillo. Estos hallazgos sugieren que la utilización del método de goniometría estática podría llevar a interpretaciones erróneas sobre el grado de elongación de la musculatura implicada durante el pedaleo. Por lo tanto, para asegurar un rango de movimiento articular óptimo se recomienda el método de goniometría dinámica, basado en el análisis 2D de la extremidad inferior durante el pedaleo, que hoy en día, se puede realizar a bajo coste (cámaras de vídeo de alta velocidad y software libre). En el tercer estudio de esta Tesis Doctoral participaron 14 ciclistas entrenados a los que se les modificó aleatoriamente su altura del sillín habitual (± 2%) pedaleando a una intensidad submáxima (70-75% del VO2max) y a cadencia fija (~90 rpm). Se demostró que pequeños cambios en la altura del sillín afectaron más a la cinemática de la extremidad inferior que a la eficiencia de pedaleo. Las diferencias entre la menor y mayor altura del sillín para la cadera, rodilla y tobillo fueron de 4, 7 y 8º de mayor extensión, 3, 4 y 4º de menor flexión, y 1, 3 y 4º de mayor rango de movimiento, respectivamente. También se observaron cambios en la eficiencia de pedaleo, si bien fue necesario modificar un 4% la altura del sillín (comparación entre la posición más baja y más alta de sillín) para detectarlos. Por lo tanto, los cambios cinemáticos justificaron, sólo en parte, los cambios en eficiencia de pedaleo. Finalmente, en el cuarto estudio, se analizó a 12 ciclistas de ruta entrenados, pedaleando a intensidad submáxima (150, 200 y 250 W) y a una cadencia de pedaleo fija (~90 rpm) para comprobar los efectos de pequeñas variaciones aleatorias (± 5 mm) de la longitud preferida de biela. Se registraron simultáneamente la cinemática y cinética del pedaleo, así como la eficiencia. Una longitud de biela mayor produjo cambios significativos en la cantidad de impulso (0.9-1.9% mayor) que los ciclistas debían realizar para pedalear, lo que se debió a un mayor torque de pedaleo máximo (1.0-2.3 N·m) y mínimo (1.0-2.2 N·m). Al mismo tiempo, aumentó la flexión y el rango de movimiento en las articulaciones de la cadera y la rodilla (1.8-3.4º) sin cambios en el tobillo. La longitud de la biela no afectó al gasto metabólico del pedaleo (frecuencia cardiaca y eficiencia de pedaleo), posiblemente porque los cambios cinemáticos y cinéticos fueron demasiado pequeños para detectarlos. La realización de esta Tesis Doctoral ha permitido extraer las siguientes conclusiones generales: 1- los métodos estáticos podrían ser utilizados como un primer ajuste de la altura óptima del sillín, teniendo en cuenta las nuevas ecuaciones o correcciones propuestas, pero deberían ir seguidos de un análisis de goniometría dinámica para garantizar una correcta cinemática de pedaleo, 2- pequeñas variaciones en la altura del sillín y en la longitud de la biela producen cambios importantes en la biomecánica del pedaleo, que explican en parte los cambios metabólicos observados, si bien estos últimos son menos sensibles a las modificaciones efectuadas ABSTRACT The performance in road cycling depends on several factors such as physiology (VO2Max, intensity, pedalling efficiency, fatigue, age, gender), environment (air-wind, atmospheric pressure, temperature, relative humidity, and the slope of the terrain) psychology, (self-talk, focus and teleoanticipation), training (strength, endurance, altitude training, heat acclimation, technique and tapering), nutrition (competitive nutritional strategy) and biomechanics (resistive forces, propulsive forces, pedalling kinematics and bicycle set-up). Although, the actual influence of some of these factors is still unknown, some studies have demonstrated the influence of proper bicycle configuration on aerodynamic drag, muscular coordinative pattern, pedal forces profile and, consequently, on energy expenditure. Saddle height and crank length are key factors in the lower limb kinetic change thus can contribute significantly on pedalling efficiency. There is some controversy in the specific cycling literature concerning the optimal method to adjust saddle height. Anthropometric references (e.g. 106-109% of the inseam length) laid down on 70’s or 80’s (when toe-clip were mainly used) are still used today. The static goniometric method (cyclists should achieve a knee angle of 25-35º with the pedal located at the bottom dead centre) has been recommended in order to improve the anthropometric one. Furthermore, it has become increasingly frequent in recent years to use the dynamic goniometric method (2d analysis during pedalling), thanks to the introduction of new technologies. In this method, cyclists should achieve a knee flexion angle of 30-40º during pedalling) with the aim of optimizing muscle length and the lever arm, which vary with saddle height changes. In high-level cycling, small details can determine the final result. Moreover, at that level, the bicycle set-up is difficult to handle because the narrow range for possible modifications. To date, some studies have demonstrated the effect of wide changes in bicycle configuration on pedalling efficiency. However, the influence of small changes in factors such as saddle height or crank length remains unclear. The present Thesis would try to explain these issues by the following aims, addressed in four chapters: 1.- Verify if the anthropometric method (adjusting saddle height from 106% to 109% of the inseam length) ensure an optimal knee angle while pedalling (dynamic method), 2- Compare the static and dynamic goniometric methods in order to adjust the saddle height and analyse if the differences between methods are dependent of the relative saddle height, 3-evaluate the acute effects of small changes in saddle height on gross efficiency and lower-limb kinematics in well-trained cyclists, 4-analyse the acute effects of small changes in crank length on the energy cost of cycling and pedalling technique (kinetic and kinematic profiles) during submaximal pedalling Twenty three high-level male cyclists of the same team participated in the first study. Results support the view that adjusting saddle height from 106% to 109% of the inseam length (anthropometric method) does not ensure an optimal knee flexion angle (30-40º) while pedalling, because these references could be valid only to toe-clip pedals instead of clipless pedals. In fact, more than the half of the cyclists (56.5%) worked out with excessive knee flexion. Furthermore, a novel algorithm was proposed (SH = 22.1 + (0.896 · E) – (0.15 · KA)) that relates the inseam length (E) and the recommended knee angle while pedalling (KA) to set an optimal saddle height (SH) using the clip-less pedals. Thirteen well-trained cyclists participated in the second study. Static goniometric method (knee flexion angle of 25-35º) underestimated knee flexion (9-12º), hip flexion (4-7º) and plantar-flexion of the ankle (7-13º) compared with the dynamic method. In addition, the differences between both methods are dependent on the relative saddle height, mainly on knee and ankle joints. These findings suggest that using the static goniometric method could lead to misinterpretation of the muscle length of the main muscles involved during cycling. Therefore, dynamic method is recommended instead of the static one, in order to ensure an optimal range of motion of the lower limb during pedalling. Furthermore, two-dimensional video analysis should be considered a useful tool to determine the kinematics of the cyclists, because it has a high correspondence with the three-dimensional analysis in the sagittal plane, is easy to use, and free software is available. Fourteen well-trained cyclists participated in the third study of this Thesis. They performed a submaximal pedalling test (~70-75% of the VO2max) at constant cadence (90 rpm).consisted on three randomized sets of 6 min with the preferred saddle height, 2% higher and 2% lower. The results of this study add to a growing body of literature that shows that changes in saddle height have acute effects on gross efficiency and on lower limb kinematics during pedalling. Raising the saddle height increased hip and knee joints extension and ankle plantarflexion (∼4, 7 y 8º, respectively) more than the decrease in hip and knee joints flexion and ankle dorsiflexion (∼3, 4 y 4º, respectively). Consequently the range of movement also increased (∼1, 3 y 4º, respectively). Furthermore, gross efficiency changed significantly when lowering the saddle 4% from the higher to the lower position. Therefore, kinematic changes justified only part of the changes in pedalling efficiency. Finally, twelve road cyclists participated in the fourth study. The cyclists performed three sets of three submaximal pedalling repetitions (150, 200 and 250 W) at a constant cadence (~90 rpm) in order to analyse the effect of randomized changes in preferred crank length (± 5 mm) on physiological (energy cost of pedalling) and biomechanical variables (kinematic and kinetic profiles). A longer crank slightly increased both maximum torque during the downstroke (1.0-2.3 N·m) and minimum torque during the upstroke, (1.0-2.2 N·m) decreasing the positive impulse proportion (0.9-1.9%). Moreover, the flexion and the range of motion of both hip and knee increased (1.8-3.4º), while the ankle joint was not affected. A longer crank did not produce significant changes in the energy cost of cycling. Therefore, kinematic and kinetic changes due to a longer crank were not significant enough to alter the pedalling efficiency. The results of the present Thesis allow to draw the following conclusions: 1- static methods could be used as a first adjustment of saddle height, taking into account the new equation or the corrections proposed. The dynamic method should be introduced after the static evaluation to ensure a proper range of motion of the lower limb; 2- small changes in saddle height and in crank length produce significant changes on pedalling biomechanics that probably explain part of the metabolic changes. Likewise, pedalling efficiency is less sensitive to changes made.
... Previous research has shown that increments in power output led to higher activation of lower limb muscles [6][7][8] and increased pedal force application 9,10 . However, most studies were conducted at fixed power output (i.e. ...
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Purpose: To employ cluster analysis to assess if cyclists would opt for different strategies in terms of neuromuscular patterns when pedaling at the power output of their second ventilatory threshold (POVT2) compared with cycling at their maximal power output (POMAX). Methods: Twenty athletes performed an incremental cycling test to determine their power output (POMAX and POVT2; first session), and pedal forces, muscle activation, muscle-tendon unit length, and vastus lateralis architecture (fascicle length, pennation angle, and muscle thickness) were recorded (second session) in POMAX and POVT2. Athletes were assigned to 2 clusters based on the behavior of outcome variables at POVT2 and POMAX using cluster analysis. Results: Clusters 1 (n = 14) and 2 (n = 6) showed similar power output and oxygen uptake. Cluster 1 presented larger increases in pedal force and knee power than cluster 2, without differences for the index of effectiveness. Cluster 1 presented less variation in knee angle, muscle-tendon unit length, pennation angle, and tendon length than cluster 2. However, clusters 1 and 2 showed similar muscle thickness, fascicle length, and muscle activation. When cycling at POVT2 vs POMAX, cyclists could opt for keeping a constant knee power and pedal-force production, associated with an increase in tendon excursion and a constant fascicle length. Conclusions: Increases in power output lead to greater variations in knee angle, muscle-tendon unit length, tendon length, and pennation angle of vastus lateralis for a similar knee-extensor activation and smaller pedal-force changes in cyclists from cluster 2 than in cluster 1.
... Five trials were collected in the following order: one trial-coupled-crank pedaling (15-s duration); one trial-pseudo-pedaling (15-s duration); and three randomly assigned trials-unilateral pedaling with contralateral rhythmic isometric force generation (35-s duration). The workload of 80 J roughly corresponds to a moderate touring pace on flat ground (Macintosh et al. 2000). The moderate workload, combined with instructions to ask for additional rest if fatigued, suggest that subjects were unlikely to be affected by fatigue. ...
Article
Locomotion requires uninterrupted transitions between limb extension and flexion. The role of contralateral sensorimotor signals in executing smooth transitions is little understood even though their participation is crucial to bipedal walking. However, elucidating neural interlimb coordinating mechanisms in human walking is difficult because changes to contralateral sensorimotor activity also affect the ipsilateral mechanics. Pedaling, conversely, is ideal for studying bilateral coordination because ipsilateral mechanics can be independently controlled. In pedaling, the anterior and posterior bifunctional thigh muscles develop needed anterior and posterior crank forces, respectively, to dominate the flexion-to-extension and extension-to-flexion transitions. We hypothesized that contralateral sensorimotor activity substantially contributes to the appropriate activation of these bifunctional muscles during the limb transitions. Bilateral pedal forces and surface electromyograms (EMGs) from four thigh muscles were collected from 15 subjects who pedaled with their right leg against a right-crank servomotor, which emulated the mechanical load experienced in conventional two-legged coupled-crank pedaling. In one pedaling session, the contralateral (left) leg pseudo-pedaled (i.e., EMG activity and pedal forces were pedaling-like, but pedal force was not allowed to affect crank rotation). In other sessions, the mechanically decoupled contralateral leg was first relaxed and then produced rhythmic isometric force trajectories during either leg flexion or one of the two limb transitions of the pedaling leg. With contralateral force production in the extension-to-flexion transition (predominantly by the hamstrings), rectus femoris activity and work output increased in the pedaling leg during its flexion-to-extension transition, which occurs simultaneously with contralateral extension-to-flexion in conventional pedaling. Similarly, with contralateral force production in the other transition (i.e., flexion-to-extension; predominantly by rectus femoris), hamstrings activity and work output increased in the pedaling leg during its extension-to-flexion transition. Therefore rhythmic isometric force generation in the contralateral leg supported the ongoing bifunctional muscle activity and resulting work output in the pedaling leg. The results suggest that neural interlimb coordinating mechanisms fine-tune bifunctional muscle activity in rhythmic lower-limb tasks to ensure limb flexion/extension transitions are executed successfully.
... But substantial negative muscular crank torque was generated at the two highest pedaling rates (105 and 120 rpm) that increased with the increasing pedaling rates. Neptune and Horton (2000) results, who described an increase of the optimal pedaling cadence (based on muscle activation) for higher workloads. While small changes in pedaling cadence (from 90 to 100 rpm) do not seem to affect joint mechanical work distribution (Broker & Gregor, 1994), wide ranges of pedaling cadence seem to change (Hoshikawa, et al., 2007;Sanderson, et al., 2008) or do not affect (Ericson, 1988) the contribution of the hip, knee, and ankle joint to the total mechanical work. ...
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In this review paper three models to calculate mechanical work, the pattern of joint power during steady-state cycling and some theories regarding energy transfer through the joints and coordinative pattern analysis by joint mechanical work distribution will be briefly presented. Finally, there will be a report on the effects of workload, pedaling cadence and saddle height management on joint mechanical work. The first result that emerges from the management of the workload is that the positive mechanical work produced by the joints increases which is mostly related to the concentric muscle contraction. The contribution of hip and knee joints seems to be different from the ankle joint with changes in workload during cycling because the ankle joint muscles should be tuned to optimize stiffness and maximize the effective transmission of mechanical energy to the crank. When changing pedaling cadence, the authors have only agreed with the unchanged contribution of the ankle joint to the total mechanical work, while the hip and knee contribution results differ in the reported research. Lack of evidence in ankle joint function when the resistive force and pedaling cadence relationship are changed during fatigue as the mechanical energy transfer and stiffness function need further research. Controversial results have been reported in the analysis of joint contribution to the total mechanical work for different cycling expertise. Unfortunately, we cannot find conclusive research regarding the effects of saddle height on coordinative pattern mainly based on simultaneous analysis of joint moment distribution, joint kinematics and joint reaction forces.
... The effect of cadence on cycling performance has been studied extensively with a majority of studies focusing on cycling energetics [1]. A number of studies have also focused on the effect of cadence on cycling technique and coordination [2][3][4]. These studies show that changing cadence leads to numerous technical responses, such as changes in muscle activation and force effectiveness [1,5,6]. ...
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Background The effect of cadence and work rate on the joint specific power production in cycling has previously been studied, but research has primarily focused on cadences above 60 rpm, without examining the effect of low cadence on joint contribution to power. Purpose Our purpose was to investigate joint specific power production in recreational and elite cyclists during low- and moderate cycling at a range of different cadences. Methods 18 male cyclists (30.9 ± 2.7 years with a work rate in watt at lactate threshold of 282.3 ± 9.3 W) performed cycling bouts at seven different pedalling rates and three intensities. Joint specific power was calculated from kinematic measurements and pedal forces using inverse dynamics at a total of 21 different stages. Results A main effect of cadence on the relative to the total joint power for hip-, knee- and ankle joint power was found (all p < 0.05). Increasing cadence led to increasing knee joint power and decreasing hip joint power (all p < 0.05), with the exception at low cadence (<60 rpm), where there was no effect of cadence. The elite cyclists had higher relative hip joint power compared to the recreational group (p < 0.05). The hip joint power at moderate intensity with a freely chosen cadence (FCC) was lower than the hip joint power at low intensity with a low cadence (<60 rpm) (p < 0.05). Conclusion This study demonstrates that there is an effect of cadence on the hip- and knee joint contribution in cycling, however, the effect only occurs from 60 rpm and upward. It also demonstrates that there is a difference in joint contribution between elite- and recreational cyclists, and provide evidence for the possibility of achieving higher relative hip joint power at low intensity than moderate intensity by altering the cadence.
... The use of a cost function [1,4,5] allows to quantify the movement cost by a single value obtained by substituting the values of several variables in a mathematical expression. Most common cost functions used in the biomechanics of cycling are based on the energy consumption [6][7][8][9], the muscle electrical activity (with electromyography, EMG) [10], the leg joint moments (which bear some relation to the muscular effort) [11][12][13], the negative muscle work [14], neuromuscular fatigue-related quantities [15] and the rating of perceived exertion (RPE) during cycling [16,17]. Seabury [6] and Marsh [7] founded that the oxygen consumption for power outputs less than 200 W is minimized for cadences between 40 and 65 rpm; for power outputs of about 300 W the optimal range for oxygen consumption is between 70 and 80 rpm [15,18]. ...
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The article presents the study of the pedalling rates obtained by minimizing a cost function based on a kinetic approach and which can be estimated with more easily achievable experimental data as input than other cost functions. Simulations based on data available in the literature were used to compare the cadences obtained by minimizing well-known joint moment-based cost functions and the proposed cost function. The influence of the power output and of the body mass index on the pedalling rates that minimize the cost function was investigated. Experimental tests performed by four competitive cyclists in the field were used as comparison for the results based on simulations. From simulations emerged that results obtained with the cost function proposed in this work were similar to those based on the absolute average joint moments. We found that the upper limit of the more convenient pedalling rate range decreases linearly with the body mass index, while it increases non-linearly with power output. Furthermore, a polynomial regression of the correlation of the pedalling rate obtained through the method and body mass index and power was found. Experimental results confirmed that the proposed model, finding an approximation of the minimum of muscular effort (not including negative muscular work), is able to estimate the upper limit of an optimal range of cadence. All tested cyclists freely choose to pedal at a cadence under this limit.
... Beyond the fact that our results revealed a significant cerebral involvement during MICT, we also observed that HHb concentration changes might be modulated by increasing intensities (resistance) during cycling. This finding is further strengthened by previous studies demonstrating that higher cadences (MacIntosh et al. 2000) and intensities (Macdonald et al. 2008) during a cycling task are associated with a higher leg muscle activation. Hence, it is reasonable to assume that an increased recruitment of muscle fibers requires higher levels of neural resources in motor-related brain areas not only on a regional but also on a network level . ...
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It is well known that endurance exercise modulates the cardiovascular, pulmonary, and musculoskeletal system. However, knowledge about its effects on brain function and structure is rather sparse. Hence, the present study aimed to investigate exercise-dependent adaptations in neurovascular coupling to different intensity levels in motor-related brain regions. Moreover, expertise effects between trained endurance athletes (EA) and active control participants (ACP) during a cycling test were investigated using multi-distance functional near-infrared spectroscopy (fNIRS). Initially, participants performed an incremental cycling test (ICT) to assess peak values of power output (PPO) and cardiorespiratory parameters such as oxygen consumption volume (VO2max) and heart rate (HRmax). In a second session, participants cycled individual intensity levels of 20, 40, and 60% of PPO while measuring cardiorespiratory responses and neurovascular coupling. Our results revealed exercise-induced decreases of deoxygenated hemoglobin (HHb), indicating an increased activation in motor-related brain areas such as primary motor cortex (M1) and premotor cortex (PMC). However, we could not find any differential effects in brain activation between EA and ACP. Future studies should extend this approach using whole-brain configurations and systemic physiological augmented fNIRS measurements, which seems to be of pivotal interest in studies aiming to assess neural activation in a sports-related context.
... At the individual muscle level, cadences faster than 120 rpm are related to increased excitation (2,12) and constant burst durations that, coupled with the shorter pedal cycle durations, result in longer duty cycles (2). In some muscles cadences above 120 rpm also lead to preferential recruitment of faster motor unit populations (13,14) and early derecruitment of slower motor unit populations in each excitation burst (15). ...
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Purpose: A key determinant of muscle coordination and maximum power output during cycling is pedalling cadence. During cycling the neuromuscular system may select from numerous solutions that solve the task demands while producing the same result. For more challenging tasks fewer solutions will be available. Changes in the variability of individual muscle excitations (EMG) and multi-muscle coordination, quantified by entropic half-life (EnHL), can reflect the number of solutions available at each system level. We therefore ask whether reduced variability in muscle coordination patterns occur at critical cadences and if they coincide with reduced variability in excitations of individual muscles. Methods: Eleven trained cyclists completed an array of cadence-power output conditions. EnHL of EMG intensity recorded from 10 leg muscles and EnHL of principal components describing muscle coordination were calculated. Multivariate adaptive regressive splines were used to determine the relationships between each EnHL and cycling condition or excitation characteristics (duration, duty cycle). Results: Muscle coordination became more persistent at cadences up to 120 r.p.m., indicated by increasing EnHL values. Changes in EnHL at the level of the individual muscles differed from the changes in muscle coordination EnHL, with longer EnHLs occurring at the slowest (< 80 r.p.m.) and fastest (>120 r.p.m.) cadences. EnHL of the main power producing muscles however reached a minimum by 80 r.p.m. and did not change across the faster cadences studied. Conclusions: Muscle coordination patterns, rather than the contribution of individual muscles, are key to power production at faster cadences in trained cyclists. Reductions in maximum power output at cadences above 120 r.p.m. could be a function of the time available to coordinate orientation and transfer of forces to the pedals.
... For example, swimming velocity decreases, if the stroke rate increases over a certain (optimal) value (Craig & Pendergast, 1979;Garland, Hiobs, & Kleshnev, 2009) and an optimal cadence allows the maximum power outputs in cycling competition (Van Soest & Casius, 2000). During cycling, each power output can be linked to a specific (optimal) cadence, which is characterised by minimal muscle activations (MacIntosh, Neptune, & Horton, 2000). It is however unclear, whether relevant SSC movement-parameters in rowing, such as stroke rate, gearing and drag factor, have to be maximised to obtain maximum power output or if an optimum relation emerges. ...
Article
Each stretch-shortening-cycle (SSC) in elite sports (e.g. jumping, cycling), is characterised by utilising optimal movement-parameters (e.g. muscle shortening velocity), for maximum power (jump height, cycle velocity). It is however unclear if relevant SSC movement-parameters in rowing, such as stroke rate and gearing, have to be maximised to obtain maximum power output or if an optimum relation emerges. Thus, we measured rowing-power (Prow), leg-power (Pleg) and work-per-stroke (WPS) at of varying stroke rates (20–45 spm), gearings (lever-changes 0.87–0.90 m) and drag factors (100–180 Ws³/m³) during rowing. Experienced sub-elite young athletes performed sprint-series on (single scull, n = 69, 20 ± 2 years, 186 ± 7 cm, 84 ± 9 kg) and off the water (rowing-ergometer, n = 30, 19 ± 3 years, 185 ± 11 cm, 77 ± 19 kg). Prow increased with stroke rate for ergometer-test (r = 0.97, p < 0.001) and boat measurement (r = 0.98, p < 0.001) by 2.7%/stroke and 4.4%/stroke, respectively. Interestingly, stroke rate had a high impact on WPS (r = 0.79, p < 0.001) during boat measurement, compared to no (or specifically no high) impact on WPS (r = −0.10, p = 0.166) during ergometer-measurements. Drag factor (ergometer: r = 0.83, p < 0.001) and gearing (boat: r = 0.60, p < 0.001) yielded moderate to high correlations to Prow. These results indicate that no optimum stroke rate, gearing and drag factor exist for maximum power in rowing (sprint-measurement-range). Accordingly, the measurements yielded maximum power for maximum stroke rate, gearing, and drag factor.
... This lack of ergogenic effect may be explained because it could be exclusive to athletes with high levels of performance, as there are other studies with poorly trained subjects where there have been no significant differences between caffeine and placebo conditions [46][47][48][49]. More deeply, MacIntosh et al. [50] and Lucia et al. [27] studied this neuromuscular efficiency in cycle ergometry with active healthy subjects and professional elite cyclists, respectively. Both showed that at high power outputs (i.e. ...
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Background: this study examined the effects of caffeine supplementation on anaerobic performance, neuromuscular efficiency and upper and lower extremities fatigue in Olympic-level boxers. Methods: Eight male athletes, members of the Spanish National Olympic Team, were enrolled in the study. In a randomized double-blind, placebo-controlled, counterbalanced, crossover design, the athletes completed 2 test sessions after the intake of caffeine (6 mg·kg-1) or placebo. Sessions involved initial measures of lactate, handgrip and countermovement jump (CMJ) performance, followed by a 30-seconds Wingate test, and then final measures of the previous variables. During the sessions, electromiography (EMG) data were recorded on the gluteus maximus, biceps femoris, vastus lateralis, gastrocnemius lateral head and tibialis anterior. Results: caffeine enhanced peak power (6.27%, p < 0.01; Effect Size (ES) = 1.26), mean power (5.21%; p < 0.01; ES = 1.29) and reduced the time needed to reach peak power (-9.91%, p < 0.01; ES = 0.58) in the Wingate test, improved jump height in the CMJ (+2.4 cm, p < 0.01), and improved neuromuscular efficiency at peak power in the vastus lateralis (ES = 1.01) and gluteus maximus (ES = 0.89), and mean power in the vastus lateralis (ES = 0.95) and tibialis anterior (ES = 0.83). Conclusions: in these Olympic-level boxers, caffeine supplementation improved anaerobic performance without affecting EMG activity and fatigue levels in the lower limbs. Further benefits observed were enhanced neuromuscular efficiency in some muscles and improved reaction speed.
... Most of the studies used to evaluate GME have been in cycling test, and cycle pedaling mainly involves concentric muscle actions (11). Various factors affect efficiency and fatigue during exercise, including muscle properties (22), the type of muscle contraction, the type of muscle action, and the exercise methodology (maximal vs. submaximal force generation and duration) (26). Studies comparing GME of the cycle ergometer and resistance exercise are needed to sustain such claims. ...
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Garnacho-Castaño, MV, Albesa-Albiol, L, Serra-Payá, N, Gomis Bataller, M, Pleguezuelos Cobo, E, Guirao Cano, L, Guodemar-Pérez, J, Carbonell, T, Domínguez, R, and Maté-Muñoz, JL. Oxygen uptake slow component and the efficiency of resistance exercises. J Strength Cond Res XX(X): 000-000, 2018-This study aimed to evaluate oxygen uptake slow component (V[Combining Dot Above]O2sc) and mechanical economy/efficiency in half squat (HS) exercise during constant-load tests conducted at lactate threshold (LT) intensity. Nineteen healthy young men completed 3 HS exercise tests separated by 48-hour rest periods: 1 repetition maximum (1RM), incremental-load HS test to establish the %1RM corresponding to the LT, and constant-load HS test at the LT. During the last test, cardiorespiratory, lactate, and mechanical responses were monitored. Fatigue in the lower limbs was assessed before and after the constant-load test using a countermovement jump test. A slight and sustained increase of the V[Combining Dot Above]O2sc and energy expended (EE) was observed (p < 0.001). In blood lactate, no differences were observed between set 3 to set 21 (p > 0.05). A slight and sustained decrease of half squat efficiency and gross mechanical efficiency (GME) was detected (p < 0.001). Significant inverse correlations were observed between V[Combining Dot Above]O2 and GME (r = -0.93, p < 0.001). Inverse correlations were detected between EE and GME (r = -0.94, p < 0.001). Significant losses were observed in jump height ability and in mean power output (p < 0.001) in response to the constant-load HS test. In conclusion, V[Combining Dot Above]O2sc and EE tended to rise slowly during constant-load HS exercise testing. This slight increase was associated with lowered efficiency throughout constant-load test and a decrease in jump capacity after testing. These findings would allow to elucidate the underlying fatigue mechanisms produced by resistance exercises in a constant-load test at LT intensity.
... Hence, much of our understanding of human and animal movement, and the effects of clinical conditions and interventions, are based on their predictions (MacIntosh et al. 2000;Hutchinson and Garcia 2002;Holzbaur et al. 2005;Hamner et al. 2010;Arnold et al. 2013;Steele et al. 2013;Hutchinson et al. 2015). ...
Article
Biological movement is an inherently dynamic process, characterized by large spatiotemporal variations in force and mechanical energy. Molecular level interactions between the contractile proteins actin and myosin do work, generating forces and transmitting them to the environment via the muscle's and supporting tissues' complex structures. Most existing theories of muscle contraction are derived from observations of muscle performance under simple, tightly controlled, in vitro or in situ conditions. These theories provide predictive power that falls off as we examine the more complicated action and movement regimes seen in biological movement. Our early and heavy focus on actin and myosin interactions have lead us to overlook other interactions and sources of force regulation. It increasingly appears that the structural heterogeneity, and micro-to-macro spatial scales of the force transmission pathways that exist between actin and myosin and the environment, determine muscle performance in ways that manifest most clearly under the dynamic conditions occurring during biological movement. Considering these interactions, along with the dynamics of force transmission tissues, actuators, and environmental physics have enriched our understanding of biological motion and force generation. This symposium brings together diverse investigators to consolidate our understanding of the role of spatial scale and structural heterogeneity role in muscle performance, with the hope of updating frameworks for understanding muscle contraction and predicting muscle performance in biological movement.
... A band-pass Butterworth filter (50-1000 Hz) and a root mean square (RMS) envelope with a window of 20 ms were applied to the EMG signals. The RMS data of each muscle were normalized to the highest peak of the average RMS curve of ten consecutive crank revolutions registered in any of the three workloads [19,20]. The mean normalized EMG RMS over the whole crank cycle was then calculated and averaged over the 10 crank revolutions. ...
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The purpose of this study was to describe the effect of increasing workload on individual thigh muscle activation during a 20 minute incremental cycling test. Intramuscular electromyographic signals were recorded from the knee extensors rectus femoris, vastus lateralis, vastus medialis and vastus intermedius and the knee flexors semimembranosus, semitendinosus, and the short and long heads of the biceps femoris during increasing workloads. Mean activation levels were compared over the whole pedaling cycle and the crank angles at which onset and offset of activation and peak activity occurred were identified for each muscle. These data were compared between three workloads. EMG activation level significantly increased (p<0.05) with increasing workload in the rectus femoris, vastus medialis, vastus lateralis, vastus intermedius, biceps femoris long head, semitendinosus and semimembranosus but not in the biceps femoris short head. A significant change in activation timing was found for the rectus femoris, vastus lateralis, vastus medialis and semitendinosus. Of the knee flexors only the short head of the biceps femoris had its peak activity during the upstroke phase at the two highest workloads indicating a unique contribution to knee flexion.
... Cycling exercise can be measured using a cycle ergometer, as it is easy to set the desired workload and pedaling rate. A number of studies have reported that pedaling rate is related to oxygen consumption, blood lactate [6], heart rate [7], and minimum electromyogram (EMG) amplitude [8]. The root mean square of EMG (RMS EMG) depends on power output, but not on pedaling rate [9]. ...
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We examined muscle stiffness at various pedaling rates under conditions of constant power output. Eight healthy young participants pedaled a cycle ergometer at a power output of 47 W. The combinations of pedaling rate and workload were 40 revolutions per min (rpm) and 11.7 N, 60 rpm and 7.8 N, and 80 rpm and 5.9 N, respectively. One electrical stimulus per two pedal rotations was applied to the vastus lateralis muscle at a crank angle of 30° in the down phase. Mechanomyograms (MMGs) were measured using a capacitor microphone, and the evoked MMG was extracted. An evoked MMG system was identified, and the coefficients of the denominator of the transfer function were used to estimate stiffness and viscous coefficient of the muscle. Muscle stiffness was 236–705 Nm⁻¹, and was proportional to the pedaling rate when power output was held constant, while the viscous coefficient did not change from approximately 15 Nm⁻¹s. In conclusion, our findings demonstrate that stiffness of the vastus lateralis muscle increases with increasing pedaling rate under conditions of constant power output, while the viscous coefficient does not change. © 2018, Japanese Society for Medical and Biological Engineering. All rights reserved.
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Im Radsport erfordern vor allem hohe Trittfrequenzen eine hohe kortikale Aktivität. Daher ist dies möglicherweise ein effizienter Stimulus für die Provokation längerfristiger Anpassungen auf zentralnervöser Ebene. In einer Laborstudie konnte gezeigt werden, dass sich bei höheren Trittfrequenzen die zentralnervöse Ermüdung verzögert. Diese Studie überprüft, inwieweit sich diese für die Trainingspraxis wichtige Erkenntnis im Feld replizieren lässt.
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The economy of running has traditionally been quantified from the mass-specific oxygen uptake; however, because fuel substrate usage varies with exercise intensity, it is more accurate to express running economy in units of metabolic energy. Fundamentally, the understanding of the major factors that influence the energy cost of running (Erun) can be obtained with this approach. Erun is determined by the energy needed for skeletal muscle contraction. Here, we approach the study of Erun from that perspective. The amount of energy needed for skeletal muscle contraction is dependent on the force, duration, shortening, shortening velocity, and length of the muscle. These factors therefore dictate the energy cost of running. It is understood that some determinants of the energy cost of running are not trainable: environmental factors, surface characteristics, and certain anthropometric features. Other factors affecting Erun are altered by training: other anthropometric features, muscle and tendon properties, and running mechanics. Here, the key features that dictate the energy cost during distance running are reviewed in the context of skeletal muscle energetics.
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The cadence that maximises power output developed at the crank by an individual cyclist is conventionally determined using a laboratory test. The purpose of this study was two-fold: (i) to show that such a cadence, which we call the optimal cadence, can be determined using power output, heart-rate, and cadence measured in the field and (ii) to describe methodology to do so. For an individual cyclist's sessions, power output is related to cadence and the elicited heart-rate using a non-linear regression model. Optimal cadences are found for two riders (83 and 70 revolutions per minute, respectively); these cadences are similar to the riders' preferred cadences (82-92 rpm and 65-75 rpm). Power output reduces by approximately 6% for cadences 20 rpm above or below optimum. Our methodology can be used by a rider to determine an optimal cadence without laboratory testing intervention: the rider will need to collect power output, heart-rate, and cadence measurements from training and racing sessions over an extended period (>6 months); ride at a range of cadences within those sessions; and calculate his/her optimal cadence using the methodology described or a software tool that implements it.
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The aim of the present study was to investigate the influence of pedalling rate and power output on negative work during cycling. Eleven subjects performed 15 testing trials in a random order, each one corresponding to a combination of one power output (60%, 80% or 100% maximal aerobic power [MAP]) and one cadence (70%, 85%, 100%, 115% or 130% of the freely chosen cadence [FCC]). Mechanical pattern was defined as the repartition of mechanical torque over the whole crank cycle, and was assessed by calculating positive and negative work generated during this pedalling cycle. Negative work could be considered as a performance limiting factor, since it has to be overcome by contralateral leg. FCC did not significantly change with power output. Both cadence and power output influenced mechanical pattern (P<0.01). Negative work, defined as the integration of negative torque versus crank angle curve, increased significantly when cadence increased and/or power output decreased and was negatively correlated (R 2=0.99, P<0.01) with mean torque during pedalling. This last result suggests that the mechanical pattern was determined by the mean torque level required for pedalling at given conditions of cadence and power output, rather than by cadence itself.
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Power output is considered one of the best tools to control external loads in cycling, but the relationship between a target power output and the physiological responses may suffer from the effects of road gradient, which is also affected by cyclist specialization. The objective of this study was to determine the effects of cyclist specialization on effort perception and physiological response (heart rate and lactate concentration) while sustaining efforts at similar power output but riding on two different road gradients. Nineteen male competitive road cyclists performed two randomized trials of 10 min at 0% (velodrome) and 10 min at 6% road gradient (field uphill), at an intensity of 10% ±3% below the individual’s functional threshold power. Cadence was kept between 75-80 in both trials and posture remained unchanged during the tests. Heart rate, speed, cadence, power output, blood lactate, and rate of perceived effort were measured for each trial. K-means cluster analyses differentiate uphill (n=10) and flat specialists (n=9) according to lactate responses. Flat specialists presented lower heart rate (p<0.001 and ES=0.2), perceived exertion (p<0.01 and ES=0.7), and blood lactate concentration (p<0.001 and ES=0.7) riding on the flat than uphill. Uphill specialists presented lower perceived exertion (p<0.01 and ES=0.8) and blood lactate concentration (p<0.01 and ES=0.5) riding uphill than on the flat. In conclusion, the combination of cyclist specialization and road gradient affects physiological and effort perception parameters in response to a similar power output demand. These factors deserve attention in training schedules and monitoring performance using power output data.
Article
This study examined differentiated rating of perceived exertion (RPE), heart rate, and heart-rate variability during light cycle ergometry exercise at two different pedal rates. 30 healthy men (22.6 +/- 0.9 yr.) were recruited from a student population and completed a continuous 20-min. cycle ergometry exercise protocol, consisting of a 4-min. warm-up (60 rev./min., 30 Watts), followed by four bouts of 4 min. at different combinations of pedal rate (40 or 80 rev./min.) and power output (40 or 80 Watts). The order of the four combinations was counterbalanced across participants. Heart rate was measuered using a polar heart-rate monitor, and parasympathetic balance was assessed through time series analysis of heart-rate variability. Measures were compared using a 2 (pedal rate) x 2 (power Output) repeated-measures analysis of variance. RPE was significantly greater (p < .05) at 80 versus 40 rev./min. at 40 W. For both power Outputs heart rate was significantly increased, and the high frequency component of heart-rate variability was significantly reduced at 80 compared with 40 rev./min. These findings indicate the RPE was greater at higher than at lower pedalling rates for a light absolute power Output Which contrasts with previous findings based on Use of higher power Output. Also, pedal rate had a significant effect on heart rate and heart-rate variability at constant power output.
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Objectives: The aim of this study was to investigate whether vibration significantly affected the efficiency of off-road cyclists. Patients and methods: Eight male mountain cyclists (mean age 21.1±1 years; range, 19 to 22 years) between August 2017 and November 2017 were included. The experimental protocol included four testing sessions with a one-day interval between testing sessions: a familiarization session; performance of submaximal tests; performance of maximal graded exercise test; and a 30-min mountain bike trial performed with vibration or without vibration. Physiological measures including volume of oxygen uptake (VO2), volume of 2), VO2, VCO2, heart rate, respiratory exchange ratio, rating of perceived exertion, and gross efficiency (GE) were compared between the trials performed with vibration or without vibration. Results: There was a significant increase in the GE with the addition of intermittent vibration, particularly over the last 15 min of the cycling trial (p<0.05). There were no significant effects of vibration on other parameters. Conclusion: This study demonstrates that addition of intermittent vibration may provide positive benefits in improving GE during a 30-min submaximal cycling trial.
Thesis
L'objectif de ce travail a été d'approfondir la connaissance des choix spontanés effectués par les humains dans le but de réaliser des tâches locomotrices simples, avec un focus sur le mouvement de pédalage. L'analyse de la transition spontanée de la position assise vers celle en danseuse en cyclisme a été le thème central de ces travaux. Peu étudiée en comparaison de la transition marche-course, cette transition est pourtant digne d'intérêt du fait des quelques possibilités de contraindre le mouvement de pédalage, et par sa nature abrupte facilitant ainsi la mise en valeur des critères optimisés lors du mouvement. Les analyses cinématiques, par électromyographie de surface, et par méthode de dynamique inverse du corps complet, ainsi que la mesure des efforts exercés en chacun des points d'appui du cycliste sur un ergocycle entièrement instrumenté ont permis l'analyse du pédalage sous un nouvel angle. La combinaison de ces procédés offre de nouvelles perspectives pour comprendre les choix spontanés effectués pour pédaler sous contrainte incrémentale de production de puissance.
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Changes in the motor evoked potential (MEP) evoked by transcranial magnetic motor cortex stimulation (TMS) of rectus femoris (RF) and vastus lateralis (VL) was examined during constant cadence cycling tasks for 60 sec. Subjects were 11 normal male volunteers aged between 19 and 25 years. Pedaling load was set at 100% and 80% of the estimated optimal value for maximum anaerobic power output. For the low load task (LL task), the pedaling rate was set at half the value of the maximum pedaling rate with the load set at 80% of the optimal for maximum anaerobic power output. For the high load task (HL task), the pedaling rate was set such that the power was equivalent to the LL task. The route mean square of the electromyographic (EMG) activity amplitude tended to steeply increase during the latter half of the task. The magnitude of the increase in the RMS was significantly larger in the HL task than the LL task. The area of the MEP also tended to increase in both tasks, though the degree of the increase was significantly larger in the LL task than the HL task. The EMG silent period (SP) after the MEP tended to steeply increase just after the task initiation and to decrease in the latter half of the task in the HL task. However, in the LL task the facilitation of MEP was not found, but it showed a gradual decrease while performing the task. The duration of the MEP tended to increase in both tasks, though the degree of the increase in the VL was significantly larger in the LL task than the HL task. The linear regression analysis between the size of the MEP and the background EMG shows a significant positive correlation coefficient during isometric contraction, but not during the two types of cycling tasks. These results suggest that the neural circuit responsible for the MEP was controlled differentially during isometric contraction and constant cadence pedaling. Also it is likely that the mechanism of central fatigue differed depending on the cadence and/or load in a task-dependent fashion irrespective of the same power output.
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The purpose of this study was to determine how tibiofemoral joint compressive forces and knee joint-spanning muscle forces during uphill walking change compared to level walking in patients with total knee arthroplasty (TKA). A musculoskeletal model capable of resolving total (TCF), medial (MCF), and lateral (LCF) tibiofemoral compressive forces was used to determine compressive forces and muscle forces during level and uphill walking on a 10° incline for twenty-five post TKA patients. A 2?2 (slope: level and 10° ? limb: replaced and non-replaced) repeated measures ANOVA was used to detect differences in knee contact forces between slope and limb conditions and their interaction. Peak loading-response TCF, MCF, and LCF were greater during uphill walking than level walking for non-replaced limbs. During uphill walking, peak loading-response TCF was smaller in the replaced limb compared to non-replaced limbs with no change in MCF or LCF. Peak knee extension moment and knee extensor muscle force were smaller in replaced limbs compared to non-replaced limbs during uphill walking. During level walking, replaced and non-replaced limbs experienced rather equal joint loading, however replaced limb experienced reduced joint loading during uphill walking. Differences in joint loading between replaced and non-replaced limbs were not present during level walking, suggesting compensation from the replaced limb during the more difficult task. Uphill walking following TKA promotes more balanced loading of replaced limbs during stance, however these benefits may come at the expense of increased loading on non-replaced limbs.
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Cyclists aim to improve pedaling technique to increase pedal force effectiveness. Therefore, biomechanical feedback about how the force is applied on the pedal stroke throughout the cycle is valuable. This information is typically presented visually on a display mounted on the handlebars. However, challenges associated with visual information presentation motivate movement researchers to display the information acoustically via parameter-mapping sonification that has shown potential for improving motor skills. This paper describes initial considerations for an application of interactive sonification for the forces applied on the pedals during cycling on the Wattbike ergometer. It was aimed to examine if the characteristics of the pedal stroke are represented in the sound to create congruency between sound, action and reaction. The primary focus is on describing the design followed by a brief summary of evaluation and practical effectiveness which was conducted on twenty-four master students (25.9 ± 3.0 years) and tested in a pilot study with four recreational cyclists (35.3 ± 0.9 years). The results of both requests indicate that sonification of the Wattbike data as an acoustic presentation of the force applied throughout the pedal stroke cycle is directly and intuitively understandable. Individual statements from testing revealed that participants became aware of characteristics within the cycling movement which they have not explicitly noticed before. The feeling for specific periods throughout the cycle was improved (pushing and pulling), and the differences in applying force on the legs (symmetry) became evident. Listening to the sound allowed cyclists to hear fluctuations in the forces applied on the pedals and thus try to adapt their muscle activation pattern. Thus, the approach presented here could serve as a helpful training tool for cyclists to optimize their cycling movement. http://www.sciencedirect.com/science/article/pii/S0141938216301706
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Relying on a five-bar linkage model of the lower limb/bicycle system, intersegmental forces and moments are computed over a full crank cycle. Experimental data enabling the solution of intersegmental loads consist of measured crank arm and pedal angles together with the driving pedal force components. Intersegmental loads are computed as a function of pedaling rate while holding the average power over a crank cycle constant. Using an algorithm that avoids redundant equations, stresses are computed in 12 lower limb muscles. Stress computations serve to evaluate a muscle stress-based objective function. The pedaling rate that minimizes the objective function is found to be in the range of 95–100 rpm. In solving for optimal pedaling rate, the muscle stresses are examined over a complete crank cycle. This examination provides insight into the functional roles of individual muscles in cycling.
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The purpose of this study was to estimate the differences in neuromuscular fatigue among prolonged pedalling exercises performed at different pedalling rates at a given exercise intensity. The integrated electromyogram (iEMG) slope defined by the changes in iEMG as a function of time during exercise was adopted as the measurement for estimating neuromuscular fatigue. The results of this experiment showed that the relationship between pedalling rate and the means of the iEMG slopes for eight subjects was a quadratic curve and the mean value at 70 rpm [1.56 (SD 0.65) Vmin–1] was significantly smaller (P < 0.01) than that at 50 and 60 rpm [2.25 (SD 0.54), and 2.22 (SD 0.68), respectively]. On the other hand, the mean value of oxygen consumption obtained simultaneously showed a tendency to increase linearly with the increase in pedalling rate, and the values at 70 and 80 rpm were significantly higher than those at 40 and 50 rpm. In conclusion, it was demonstrated that the degree of neuromuscular fatigue estimated by the iEMG changes for five periods of prolonged pedalling exercise at a given exercise intensity was different among the different pedalling rates, and that the pedalling rate at which minimal neuromuscular fatigue was obtained was not coincident with the rate at which the minimal oxygen consumption was obtained, but was coincident with the rate which most subjects preferred. These findings would suggest that the reason why most people prefer a relative higher pedalling rate, even though higher oxygen consumption is required, is closely related to the development of neuromuscular fatigue in the working muscles.
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The purpose of this study was to clarify the reason for the difference in the preferred cadence between cyclists and noncyclists. Male cyclists and noncyclists were evaluated in terms of pedal force, neuromuscular activity for lower extremities, and oxygen consumption among the cadence manipulation (45, 60, 75, 90, and 105 rpm) during pedaling at 150 and 200 W. Noncyclists having the same levels of aerobic and anaerobic capacity as cyclists were chosen from athletes of different sports to avoid any confounding effect from similar kinetic properties of cyclists for lower extremities (i.e., high speed contraction and high repetitions in prolonged exercise) on both pedaling performance and preferred cadence. The peak pedal force significantly decreased with increasing of cadence in both groups, and the value for noncyclists was significantly higher than that for cyclists at each cadence despite the same power output. The normalized iEMG for vastus lateralis and vastus medialis muscles increased in noncyclists with rising cadence; however, cyclists did not show such a significant increase of the normalized iEMG for the muscles. On the other hand, the normalized iEMG for biceps femoris muscle showed a significant increase in cyclists while there was no increase for noncyclists. Oxygen consumption for cyclists was significantly lower than that for noncyclists at 105 rpm for 150 W work and at 75, 90, and 105 rpm for 200 W work. We conclude that cyclists have a certain pedaling skill regarding the positive utilization for knee flexors up to the higher cadences, which would contribute to a decrease in peak pedal force and which would alleviate muscle activity for the knee extensors. We speculated that pedaling skills that decrease muscle stress influence the preferred cadence selection, contributing to recruitment of ST muscle fibers with fatigue resistance and high mechanical efficiency despite increased oxygen consumption caused by increased repetitions of leg movements.
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To study the effect of growth upon maximal anaerobic power of the upper and lower limbs, the maximal power developed during a cranking force-velocity test was correlated with the height of a vertical jump in different age groups of young swimmers. The youngest swimmers were significantly less powerful than the oldest. Differences in body size partly accounted for the differences in maximal power during cranking exercise (Wmax = 0.31 + 0.048 age; r = 0.526; P less than 0.01; where Wmax was expressed in W.kg BM-1 and age in months; n = 103). The effect of growth upon vertical jump is similar to the effect upon maximal cranking power: the lowest values were similar to those which concerned Wmax.kg-1. There was a very significant correlation between Wmax in cranking (in W.kg-1) and the height of the vertical jump (VJ in cm) (Wmax = 1.15 + 0.145 VJ; r = 0.728; n = 103, P less than 0.01).
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The force-velocity relationship on a Monark ergometer and the vertical jump height have been studied in 152 subjects practicing different athletic activities (sprint and endurance running, cycling on track and/or road, soccer, rugby, tennis and hockey) at an average or an elite level. There was an approximately linear relationship between braking force and peak velocity for velocities between 100 and 200 rev.min-1. The highest indices of force P0, velocity V0 and maximal anaerobic power (Wmax) were observed in the power athletes. There was a significant relationship between vertical jump height and Wmax related to body mass.
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The mechanical efficiency of mouse fast- and slow-twitch muscle was determined during contractions involving sinusoidal length changes. Measurements were made of muscle length, force production and initial heat output from bundles of muscle fibres in vitro at 31 degrees C. Power output was calculated as the product of the net work output per sinusoidal length cycle and the cycle frequency. The initial mechanical efficiency was defined as power output/(rate of initial heat production+power output). Both power output and rate of initial heat production were averaged over a full cycle of length change. The amplitude of length changes was +/- 5% of muscle length. Stimulus phase and duration were adjusted to maximise net work output at each cycle frequency used. The maximum initial mechanical efficiency of slow-twitch soleus muscle was 0.52 +/- 0.01 (mean +/- 1 S.E.M. N = 4) and occurred at a cycle frequency of 3 Hz. Efficiency was not significantly different from this at cycle frequencies of 1.5-4 Hz, but was significantly lower at cycle frequencies of 0.5 and 1 Hz. The maximum efficiency of fast-twitch extensor digitorum longus muscle was 0.34 +/- 0.03 (N = 4) and was relatively constant (0.32-0.34) over a broad range of frequencies (4-12 Hz). A comparison of these results with those from previous studies of the mechanical efficiency of mammalian muscles indicates that efficiency depends markedly on contraction protocol.
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A group of 15 untrained male subjects pedalled on a friction-loaded cycle ergometer as fast as possible for 5-7 s to reach the maximal velocity (vmax) against different braking forces (FB). Power was averaged during a complete crank rotation by adding the power dissipated against FB to the power necessary to accelerate the flywheel. For each sprint, determinations were made of peak power output (Wpeak), power output attained at vmax (Wvmax) calculated as the product of vmax and FB and the work performed to reach vmax expressed in mean power output (Wvmax). The relationships between these parameters and FB were examined. A biopsy taken from the vastus lateralis muscle and tomodensitometric radiographs of both thighs were taken at rest to identify muscle metabolic and morphometric properties. The Wpeak value was similar for all FB. Therefore, the average of values was defined as corrected maximal power (Wmax). This value was 11% higher than the maximal power output uncorrected for the acceleration. Whereas the Wmax determination did not require high loads, the highest Wvmax value (Wmax) was produced when loading was heavy, as evidenced by the Wvmax-FB parabolic relationship. For each subject, the braking force (FB,Wmax) giving Wmax was defined as optimal. The FB,Wmax, equal to 0.844 (SD 0.108) N.kg-1 bodymass, was related to thigh muscle area (r = 0.78, P < 0.05). The maximal velocity (vm,Wmax) reached against this force seemed to be related more to intrinsic fibre properties (% fast twitch b fibre area and adenylate kinase activity). Thus, from the Wmax determination, it is suggested that it should be possible to predict the conditions for optimal exercise on a cycle ergometer.
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Based on the spline software of Lyche et al., a subroutine package is presented in which the amount of smoothing on a set of n noisy datapoints is determined from the data by means of the Generalized Cross-Validation (GCV) or predicted Mean-Squared Error (MSE) criteria of Wahba and her collaborators. Following an idea of Hutchinson and de Hoog, an efficient O (m2n) algorithm is used for calculating the criterion functions, where 2m is the order of the spline function. In this fashion, earlier O (n3) approaches based on the singular value decomposition can be avoided.
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Five voluntee subjects held isometric handgrip contractions at specific submaximal tensions until the required tension could no longer be maintained. At the start of those contractions, the amplitude of the surface electromyogram (EMG) was linearly related to the tension exerted; the amplitude of the EMG increased linearly throughout these substained contractions by a constant amount--about 30% of the maximum. During sustained contractions, brief, intermittent maximal efforts showed that strength declined linearly at all tensions. At 25% maximal voluntary contraction (MVC), there was a linear fall in the EMG amplitude associated with the brief maximal efforts, but the fall in strength was more rapid than the fall in EMG amplitude. At 70% MVC, there was no fall in the EMG amplitude in response to the brief maximal efforts, while the muscle strength fell linearly.
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After review of previous studies, it seemed desirable to investigate further the interrelationships between pedalling rate, power output, and energy expenditure, using bicycle ergometry as a model for recreational bicycling. Three young adult male subjects rode a Monark ergometer at eight pedalling rates (30-120 rev min ) and four power outputs (‘ 0 ’ 81-7. 163-4. and 1961 W) [vdot] o2 determinations were made, and using measured R, gross energy expenditure was derived. When these values were combined with the results of other researchers using similar protocol but different power outputs, it was found that: (I) a ‘ most efficient’ pedalling rate exists for each power output studied: (2) the ( most efficient ) pedalling rate increases with power output from 42 rev min at 40-8 W to 62 rev min at 326-8 W: and (3) the increase in energy expenditure observed when pedalling slower than‘ most efficient’ is more pronounced at high power outputs than at low outputs, while the increase in response to pedalling faster than “lsquo; most efficient’ is less pronounced at high power outputs than at low outputs. Thus, there is appreciable interaction between pedalling rate and power output in achieving the ‘ most efficient ’ rate in bicycle ergometry. The ‘ most efficient’ pedalling rate observed at high power outputs in the present study is considerably lower than that reported for racing cyclists by others. This discrepancy may well be related to the difference in swing weights between the ergomeler' s heavy steel flywheel and crankset, and that of the lightweight wheel and crankset used on racing bicycles.
Electromyographic (EMG) activity of m. rectus femoris muscle was registered from young male and female subjects during maintained isometric knee extension at 60% of maximal voluntary contraction. The following EMG parameters were analyzed for the entire fatigue time: integrated EMG (IEMG), averaged motor unit potential (AMUP) and power spectral density function (PSDF). The results indicated a slight but continuous rise of IEMG during the fatigue period. AMUP showed sensitivity to fatigue with increase in amplitude, rise time, and number of spikes counted. PSDF was also easily affected by fatigue so that the total power density curve was shifted towards lower frequencies with a high frequency decay. The mean power frequency decreased linearily as a function of fatigue time. The findings suggest that in addition to natural recruitment of new motor units the fatigue is characterized by marked reduction in the conduction velocities of action potential along the used muscle fibers.
This study was conducted to determine whether the pedaling frequency of cycling at a constant metabolic cost contributes to the pattern of fiber-type glycogen depletion. On 2 separate days, eight men cycled for 30 min at approximately 85% of individual aerobic capacity at pedaling frequencies of either 50 or 100 rev.min-1. Muscle biopsy samples (vastus lateralis) were taken immediately prior to and after exercise. Individual fibers were classified as type I (slow twitch), or type II (fast twitch), using a myosin adenosine triphosphatase stain, and their glycogen content immediately prior to and after exercise quantified via microphotometry of periodic acid-Schiff stain. The 30-min exercise bout resulted in a 46% decrease in the mean optical density (D) of type I fibers during the 50 rev.min-1 condition [0.52 (0.07) to 0.28 (0.04) D units; mean (SEM)] which was not different (P > 0.05) from the 35% decrease during the 100 rev.min-1 condition [0.48 (0.04) to 0.31 (0.05) D units]. In contrast, the mean D in type II fibers decreased 49% during the 50 rev.min-1 condition [0.53 (0.06) to 0.27 (0.04) units]. This decrease was greater (P < 0.05) than the 33% decrease observed in the 100 rev.min-1 condition [0.48 (0.04) to 0.32 (0.06) units). In conclusion, cycling at the same metabolic cost at 50 rather than 100 rev.min-1 results in greater type II fiber glycogen depletion. This is attributed to the increased muscle force required to meet the higher resistance per cycle at the lower pedal frequency.(ABSTRACT TRUNCATED AT 250 WORDS)
Article
We determined that the variability in the oxygen cost and thus the caloric expenditure of cycling at a given work rate (i.e., cycling economy) observed among highly endurance-trained cyclists (N = 19; mean +/- SE; VO2max, 4.9 +/- 0.1 l.min-1; body weight, 71 +/- 1 kg) is related to differences in their % Type I muscle fibers. The percentage of Type I and II muscle fibers was determined from biopsies of the vastus lateralis muscle that were histochemically stained for ATPase activity. When cycling a Monark ergometer at 80 RPM at work rates eliciting 52 +/- 1, 61 +/- 1, and 71 +/- 1% VO2max, efficiency was determined from the caloric expenditure responses (VO2 and RER using open circuit spirometry) to steady-state exercise. Gross efficiency (GE) was calculated as the ratio of work accomplished.min-1 to caloric expenditure.min-1, whereas delta efficiency (DE) was calculated as the slope of this relationship between approximately 50 and 70% VO2max. The % Type I fibers ranged from 32 to 76%, and DE when cycling ranged from 18.3 to 25.6% in these subjects. The % Type I fibers was positively correlated with both DE (r = 0.85; P less than 0.001; N = 19) and GE (r = 0.75; P less than 0.001; N = 19) during cycling. Additionally, % Type I fibers was positively correlated with GE (r = 0.74; P less than 0.001; N = 13) measured during the novel task of two-legged knee extension; performed at a velocity of 177 +/- 6 degrees.s-1 and intensity of 50 and 70% of peak VO2 for that activity.(ABSTRACT TRUNCATED AT 250 WORDS)
Article
The aim of the study was to quantify the activity as recorded by electromyography during ergometer cycling in eleven different muscles of the lower extremity. Eleven healthy subjects rode in twelve different ways at different work-load, pedalling rate, saddle height and pedal foot position. Vastus medialis and lateralis, gastrocnemius medialis and lateralis and the soleus muscle were the most activated muscles. Changes in muscle activity during different calibrations were studied in eight of the eleven muscles. An increase in work-load significantly increased the mean maximum activity in all the eight muscles investigated. An increase of the pedalling rate increased the activity in the gluteus maximus, gluteus medius, vastus medialis, medial hamstring, gastrocnemius medialis and soleus muscles. An increase of the saddle height increased the muscle activity in the gluteus medius, medial hamstring and gastrocnemius medialis muscles. Use of a posterior pedal foot position increased the activity in the gluteus medius and rectus femoris muscles, and decreased the activity in the soleus muscle.
This experiment was designed to estimate the optimum pedal rates at various power outputs on the cycle ergometer. Five trained bicycle racers performed five progressive maximal tests on the ergometer. Each rode at pedal rates of 40, 60, 80, 100, and 120 rev X min-1. Oxygen uptake and heart rate were determined from each test and plotted against pedal rate for power outputs of 100, 150, 200, 250, and 300 W. Both VO2 and heart rate differed significantly among pedal rates at equivalent power outputs, the variation following a parabolic curve. The low point in the curve was taken as the optimal pedal rate; i.e., the pedal rate which elicited the lowest heart rate or VO2 for a given power output. When the optimum was plotted against power output the variation was linear. These results indicate that an optimum pedal rate exists in this group of cyclists. This optimum pedal rate increases with power output, and when our study is compared to studies in which elite racers, or non-racers were used, the optimum seems to increase with the skill of the rider.
Article
Moving average electromyography (MA) of quadriceps muscle bellies has been recorded during bicycling at different rates (30-70 cycles/min) or forces (1-3 kg). For power increments (50-100%) achieved by increasing force at constant rate, MA during pedal downstroke always increased. For similar power increments achieved by increasing the rate at constant force, MA did not increase (37% of cases), increased less (37%), or increased similarly (26%). Investigations by others on the rat suggest that the lack of increase of MA despite power increment was not compensated by other muscle activity; hence it indicates a shift from slow to fast fibers, which provide greater power per unit stimulus. Smaller increase of MA with increasing rate rather than force at isopower could depend on this shift or on muscle properties, if operating on ascending limb of power-velocity curve. This, however, does not seem the case for slow fibers, which should develop peak power at about 25 cycles/min. Hence, fibers of quadriceps muscle of humans seem selectively activated according to movement speed, as previously found in inspiratory muscles of rabbits.
Article
A cycle ergometer has been designed to measure the force exerted on the pedal cranks during maximum effort at a variety of constant velocities. Preset crank velocities of 13-166 rpm are established by a controlled 3-hp motor and cannot be overcome by the subject. Torque is measured by strain gauges bonded to the crank shafts; peak torque, peak power, work, and average power are derived for each pedal cycle. Studies in 30 healthy male subjects established reproducibility and normal standards. During exercise for 45 s at a constant velocity of 60 rpm, there was a wide intersubject variation in both maximal torque (118-226 N . m) and the percentage decline in torque (27.2-52.0%). The decline in torque was inversely related to maximal O2 intake (r = 0.84). During short (10-s) periods of exercise at six crank velocities between 60-160 rpm, a linear inverse relationship between maximal peak torque and pedal crank velocity was observed. The peak torque-velocity relationship and the percentage decline in peak torque during 30 s exercise at 60, 100, and 140 rpm were reproducible within a given subject, the coefficient of variation was less than 10%.
Article
This investigation was undertaken to determine the effect of pedal frequency on submaximal exercise responses. Seven well-trained competitive cyclists were studied riding their road-racing bicycles on a motor-driven treadmill at 80% of maximum O2 consumption (VO2 max) using different gear ratios. Cyclists were also studied during a series of unloaded trials to assess the effects of varying rates of limb movements independent of external work load. Heart rate (HR) increased, whereas net HR (after subtracting the HR during unloaded cycling) decreased with increasing pedal frequency during loaded cycling. Expiratory flow (VE), O2 consumption (VO2), blood lactate, net VO2 (after subtracting the VO2 of unloaded cycling), and net VE (after subtracting the VE during unloaded cycling) were quadratically related to pedal frequency. The quadratic relationships evident after corrections were made for the additional work needed to move the legs more frequently may be explained at the lower pedaling rates by a less uniform pattern of blood flow caused by increasing the force requirement per pedal stroke and, at the higher pedal frequencies, by the recruitment of additional musculature to stabilize the trunk. The average of preferred frequency for the group, which was also the most economical pedaling rate judged by most of the variables was 91 rpm, although the preferred pedaling rate for each subject ranged from 72 to 102 rpm.
Article
In nine male volunteers, the endurance time for sustained isometric exercise (right-angle elbow flexion) and dynamic exercise (continuous concentric and eccentric elbow flexions) was measured at different contraction levels. Intermittent isometric exercises were also performed by four of the subjects in whom surface electromyographic elbow flexor recordings were obtained during the three types of exercise. A rapid decrease of the endurance time was seen at contraction levels above 15-20% of the maximum voluntary contraction for both the sustained isometric and dynamic exercise. There were no significant difference between the regression of the endurance time vs. the contraction level for the sustained isometric exercise and that of the dynamic exercise. However, the endurance time was enhanced in the intermittent isometric exercise compared with the sustained isometric exercise. The development of muscle fatigue was well correlated to change of the myoelectric rootmean-square amplitude and the mean power frequency. Differences in exercise did not significantly affect the relation between the time constant of the mean power frequency decrease and the endurance time.
Article
Male cyclists (N = 8) and noncyclists (N = 8) pedaled under six randomly ordered cadences (50, 65, 80, 95, 110 rpm and the preferred cadence) at 200 W to test the hypothesis that electromyographic activity of selected lower limb muscles is minimized at the preferred cadence. Average preferred cadences for cyclists (85.2 +/- 9.2 rpm) and noncyclists (91.6 +/- 10.5 rpm) were not statistically different. Only gastrocnemius EMG was affected substantially and systematically by cadence changes, increasing linearly with cadence increases. Rectus femoris and vastus lateralis EMG displayed significant quadratic and linear relationships with cadence, respectively, but EMG differences between cadences were small for both muscles. Noncyclists did not exhibit significantly different patterns of muscle activity from cyclists, although there was a trend for soleus and gastrocnemius EMG to be higher in noncyclists. The results did not support our hypothesis that lower extremity muscle activation is minimized at an individual's preferred pedaling cadence. Thus, preferred cadence selection does not appear to be related to minimization of muscle activation. Given the nonlinear relationships between muscle mechanical properties, force, and EMG it is unlikely that a simple relationship exists between EMG and muscle stress.
Article
In human locomotion the ability to generate and sustain power output is of fundamental importance. This review examines the implications for power output of having variability in the metabolic and contractile properties within the population of muscle fibres which comprise the major locomotory muscles. Reference is made to studies using an isokinetic cycle ergometer by which the global power/velocity relationship for the leg extensor muscles can be determined. The data from these studies are examined in the light of the force velocity characteristics of human type I and type II muscle fibres. The 'plasticity' of fibre properties is discussed with reference to the 'acute' changes elicited by exercise induced fatigue and changes in muscle temperature and 'chronic' changes occurring following intensive training and ageing.
Article
The purpose of this study was to compare 1) the preferred cadences and 2) the aerobic demand response to cadence manipulation of highly fit, experienced cyclists and equally fit noncyclists. Eight cyclists (C) and eight non-cyclists (NC) pedaled at 200 W under six randomly ordered cadence conditions (50, 65, 80, 95, 110 rpm and preferred cadence) on a Velodyne trainer. The VO2 responses of C and NC to cadence manipulation were similar. Both groups displayed lower VO2 values at lower cadences. VO2 differences between C and NC across cadences were not significant. Mean preferred pedaling cadence surprisingly was somewhat higher for NC (91.6 +/- 10.5 rpm) than C (85.2 +/- 9.2 rpm), but the difference was not significant. The most economical cadence was significantly lower for C (56.1 +/- 6.9 rpm) than NC (62.9 +/- 4.7 rpm). Thus, cycling experience did not substantially influence preferred cadence nor economy during moderate intensity cycling by highly fit athletes. We speculate that preferred cadence and economy similarities between C and NC are associated with similarities in the dynamic muscular training of the groups.
Article
1. In this study, the efficiency of energy conversion in skeletal muscles from the mouse was determined before and after a series of contractions that produced a moderate level of fatigue. 2. Initial mechanical efficiency was defined as the ratio of mechanical power output to the rate of initial enthalpy output. The rate of initial enthalpy output was the sum of the power output and rate of initial heat output. Heat output was measured using a thermopile with high temporal resolution. 3. Experiments were performed in vitro (25 degrees C) using bundles of fibres from fast-twitch extensor digitorum longus (EDL) and slow-twitch soleus muscles from mice. Muscles were fatigued using a series of thirty isometric tetani. Initial mechanical efficiency was determined before and again immediately after the fatigue protocol using a series of isovelocity contractions at shortening velocities between 0 and the maximum shortening velocity (Vmax). Efficiency was determined over the second half of the shortening at each velocity. 4. The fatigue protocol significantly reduced maximum isometric force Vmax, maximum power output and flattened the force-velocity curve. The magnitude of these effects was greater in EDL muscle than soleus muscle. In unfatigued muscle, the maximum mechanical efficiency was 0.333 for EDL muscles and 0.425 for soleus muscles. In both muscle types, the fatiguing contractions caused maximum efficiency to decrease. The magnitude of the decrease was 15% of the pre-fatigue value in EDL and 9% in soleus. 5. In a separate series of experiments, the effect of the fatigue protocol on the partitioning of energy expenditure between crossbridge and non-crossbridge sources was determined. Data from these experiments enabled the efficiency of energy conversion by the crossbridges to be estimated. It was concluded that the decrease in initial mechanical efficiency reflected a decrease in the efficiency of energy conversion by the crossbridges.
Article
A simulation based on a forward dynamical musculoskeletal model was computed from an optimal control algorithm to understand uni- and bi-articular muscle coordination of maximum-speed startup pedaling. The muscle excitations, pedal reaction forces, and crank and pedal kinematics of the simulation agreed with measurements from subjects. Over the crank cycle, uniarticular hip and knee extensor muscles provide 55% of the propulsive energy, even though 27% of the amount they produce in the downstroke is absorbed in the upstroke. Only 44% of the energy produced by these muscles during downstroke is delivered to the crank directly. The other 56% is delivered to the limb segments, and then transferred to the crank by the ankle plantarflexors. The plantarflexors, especially soleus, also prevent knee hyperextension, by slowing the knee extension being produced during downstroke by the other muscles, including hamstrings. Hamstrings and rectus femoris make smooth pedaling possible by propelling the crank through the stroke transitions. Other simulations showed that pedaling can be performed well by partitioning all the muscles in a leg into two pairs of phase-controlled alternating functional groups, with each group also alternating with its contralateral counterpart. In this scheme, the uniarticular hip/knee extensor muscles (one group) are excited during downstroke, and the uniarticular hip/knee flexor muscles (the alternating group) during upstroke. The ankle dorsiflexor and rectus femoris muscles (one group of the other pair) are excited near the transition from upstroke to downstroke, and the ankle plantarflexors and hamstrings muscles (the alternating group) during the downstroke to upstroke transition. We conclude that these alternating functional muscle groups might represent a centrally generated primitive for not only pedaling but also other locomotor tasks as well.
Article
The purpose of the study was to develop an equation to predict the oxygen cost of cycle ergometry. Forty subjects performed an incremental cycle ergometer test on three occasions at 50, 70, or 90 rpm in a counterbalanced order. Work rate was incremented every 5 or 6 min when steady rate values were achieved. To ensure accurate work rates, ergometer resistance was calibrated and flywheel revolutions were electronically measured. Oxygen consumption was measured with a computer interfaced system which provided results every minute. Oxygen consumption (mL.min-1) was the dependent variable, and independent variables were work rate (WR in kgm.min-1), pedal rate (rpm), weight (Kg), and gender (males, 0; females, 1). The following nonlinear equation was selected; VO2 = 0.42.WR1.2 + 0.00061.rpm3 + 6.35.Wt + 0.1136.RPM50.WR-0.10144.RPM90-WR-52-Gender, R2 = 0.9961, Sy.x = 106 mL.min-1, where RPM50: 50 rpm = 1, and RPM90: 90 rpm = 1, else = 0. It was concluded that the oxygen cost of cycle ergometry is nonlinearly related to work rate and pedal rate, linearly related to weight, and that females use less oxygen for a particular work rate.
Article
There are minimal scientific data describing international caliber off-road cyclists (mountain bikers), particularly as they compare physiologically with international caliber road cyclists. Elite female (N = 10) and male (N = 10) athletes representing the United States National Off-Road Bicycle Association (NORBA) Cross-Country Team were compared with elite female (N = 10) and male (N = 10) athletes representing the United States Cycling Federation (USCF) National Road Team. Submaximal and maximal exercise responses were evaluated during the "championship" phase of the training year when athletes were in peak condition. All physiological tests were conducted at 1860 m. Among the female athletes, physiological responses at lactate threshold (LT) and during maximal exercise (MAX) were similar between NORBA and USCF cyclists with two exceptions: 1) USCF cyclists demonstrated a significantly greater (P < 0.05) absolute (16%) and relative (10%) maximal aerobic power, and 2) MAX heart rate was significantly higher (P < 0.05) for the USCF athletes (6%). Among the male athletes, physiological responses at LT and MAX were similar between NORBA and USCF cyclists with two exceptions: 1) USCF cyclists produced significantly greater (P < 0.05) absolute (18%) and relative (16%) power at LT, and 2) USCF cyclists produced significantly greater (P < 0.05) absolute (12%) and relative (10%) power at MAX. These data suggest that, in general, elite off-road cyclists possess physiological profiles that are similar to elite road cyclists.