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Abstract

Fourteen competitive cyclists who possessed a similar maximum O2 consumption (VO2 max; range, 4.6-5.0 l/min) were compared regarding blood lactate responses, glycogen usage, and endurance during submaximal exercise. Seven subjects reached their blood lactate threshold (LT) during exercise of a relatively low intensity (group L) (i.e., 65.8 +/- 1.7% VO2 max), whereas exercise of a relatively high intensity was required to elicit LT in the other seven men (group H) (i.e., 81.5 +/- 1.8% VO2 max; P less than 0.001). Time to fatigue during exercise at 88% of VO2 max was more than twofold longer in group H compared with group L (60.8 +/- 3.1 vs. 29.1 +/- 5.0 min; P less than 0.001). Over 92% of the variance in performance was related to the % VO2 max at LT and muscle capillary density. The vastus lateralis muscle of group L was stressed more than that of group H during submaximal cycling (i.e., 79% VO2 max), as reflected by more than a twofold greater (P less than 0.001) rate of glycogen utilization and blood lactate concentration. The quality of the vastus lateralis in groups H and L was similar regarding mitochondrial enzyme activity, whereas group H possessed a greater percentage of type I muscle fibers (66.7 +/- 5.2 vs. 46.9 +/- 3.8; P less than 0.01). The differing metabolic responses to submaximal exercise observed between the two groups appeared to be specific to the leg extension phase of cycling, since the blood lactate responses of the two groups were comparable during uphill running. These data indicate that endurance can vary greatly among individuals with an equal VO2 max.(ABSTRACT TRUNCATED AT 250 WORDS)

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... The (first) lactate threshold discriminates moderate-from heavyintensity exercise and can be determined by gas exchange and/or blood lactate measurements (Poole et al., 2020). Typically, values approximate 75-85% ofVO 2max in athletes (Coyle et al., 1988;Seiler and Kjerland, 2006;Joyner and Coyle, 2008). Knowing that all Olympic endurance events are decided at intensities above 85% ofVO 2max (Joyner and Coyle, 2008), athletes benefit from being relatively fatigue resistant at high exercise intensities and in this context a high lactate threshold can be very advantageous. ...
... In this view, having large oxidative muscle fibers theoretically benefits endurance performance. In practice, however, FCSA appears negatively related to endurance performance (Coyle et al., 1988;Bishop et al., 2000) and lactate threshold (Bishop et al., 2000) in cyclists. The muscle fiber type-fiber size paradox may explain this through a profound inverse relationship between FCSA and muscle fiber oxidative capacity across animal species van Wessel et al., 2010) and in competitive cyclists (van der Zwaard et al., 2018b). ...
... Muscle oxygen supply capacity to the muscle fibers is critical to sustain endurance performance. Endurance athletes are known for their well-developed capillarization compared to untrained or non-endurance athletes (Saltin et al., 1977;Sjøgaard, 1984;Tesch et al., 1984;Coyle et al., 1988;Aagaard et al., 2011;van der Zwaard et al., 2018a,b), demonstrating high number of capillaries around the fiber (∼5-8), capillary-to-fiber ratios (∼2.5-3.0), and capillary densities (∼400-700 caps/mm 2 ). Whereas, untrained individuals have 3-4 capillaries around the fiber (Saltin et al., 1977), professional road cyclists (Sjøgaard, 1984) and Olympic track cyclist (van der Zwaard et al., 2018b) displayed values as high as 9 capillaries around the fiber. ...
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In the past decades, researchers have extensively studied (elite) athletes' physiological responses to understand how to maximize their endurance performance. In endurance sports, whole-body measurements such as the maximal oxygen consumption, lactate threshold, and efficiency/economy play a key role in performance. Although these determinants are known to interact, it has also been demonstrated that athletes rarely excel in all three. The leading question is how athletes reach exceptional values in one or all of these determinants to optimize their endurance performance, and how such performance can be explained by (combinations of) underlying physiological determinants. In this review, we advance on Joyner and Coyle's conceptual framework of endurance performance, by integrating a meta-analysis of the interrelationships, and corresponding effect sizes between endurance performance and its key physiological determinants at the macroscopic (whole-body) and the microscopic level (muscle tissue, i.e., muscle fiber oxidative capacity, oxygen supply, muscle fiber size, and fiber type). Moreover, we discuss how these physiological determinants can be improved by training and what potential physiological challenges endurance athletes may face when trying to maximize their performance. This review highlights that integrative assessment of skeletal muscle determinants points toward efficient type-I fibers with a high mitochondrial oxidative capacity and strongly encourages well-adjusted capillarization and myoglobin concentrations to accommodate the required oxygen flux during endurance performance, especially in large muscle fibers. Optimisation of endurance performance requires careful design of training interventions that fine tune modulation of exercise intensity, frequency and duration, and particularly periodisation with respect to the skeletal muscle determinants.
... The more oxygen the athlete has for use in muscle work, the more efficient they will be, which is why athletes in endurance sports strive to achieve high values of this indicator. However, even the best athletes are unable to maintain the intensity of the effort corresponding to VO2max during several minutes of effort [3,5]. ...
... For competitors who have the same VO2max values, a person with a higher % VO2max will achieve better results. Coyle and co-authors [5] studied cyclists with similar VO2max, who they divided into two groups, i.e. with a low AT threshold of 65.8% VO2max and a high 81.5% VO2max. Everyone made an effort on 88% VO2max. ...
... Pol. J. Sport Tourism 2020, 27(1),[3][4][5][6][7][8] ...
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Introduction. The aim of the research was to assess the changes in the main physical performance indicators, i.e. maximum oxygen uptake (VO 2max ), the threshold of anaerobic changes (AT) and “exercise efficiency” (oxygen consumption/power; VO 2 / WR) in amateur mountain bikers in the preparatory period. In addition, diagnostic usefulness was made of selected respiratory, circulatory and metabolic parameters to assess the training progress in cycling. Materials and methods. Thirty-six men training in amateur mountain biking took part in the research. Each of them underwent three ergospirometry tests at the beginning, in the middle (after 7 weeks) and at the end of the preparatory period (after 14 weeks). The results obtained at the AT threshold and at maximum effort were analysed to check how physical training in the preparatory period affected selected exercise parameters. Results. No significant changes in the VO 2max value were observed during the preparatory period, but a significant increase in this indicator (in absolute terms and in terms of body weight) was found at the AT level. An increase was noted in power as well as in measured metabolic, ventilation and circulatory parameters with the exception of heart rate and ventilation equivalent oxygen. VO 2 /WR decreased, which indicates an improvement in the effectiveness of the effort. Conclusions. For Polish amateur cyclists with extensive training experience, the most diagnostic indicators in the preparatory period include improving the AT threshold (shift towards higher % VO 2max and higher generated power) and increasing exercise efficiency.
... It has long been recognized that fatigue during exercise, and thus endurance performance ability, is related to muscle lactic acid production and that the degree of muscular metabolic stress can be assessed from lactate concentration in the blood (Costill 1970;Margaria et al. 1933). In cyclists with homogenous maximal oxygen consumptions (VO 2max ) the primary predictor of endurance of performance is the blood lactate threshold (LT) (Coyle 1995;Coyle et al. 1988Coyle et al. , 1991. The % VO 2max at LT can range from 60 to 85% in well-trained cyclists despite similarly high VO 2max values (Coyle et al. 1988). ...
... In cyclists with homogenous maximal oxygen consumptions (VO 2max ) the primary predictor of endurance of performance is the blood lactate threshold (LT) (Coyle 1995;Coyle et al. 1988Coyle et al. , 1991. The % VO 2max at LT can range from 60 to 85% in well-trained cyclists despite similarly high VO 2max values (Coyle et al. 1988). Part of the large differences in LT can be explained by differences in mitochondrial activity Joyner and Coyle 2008), but we have Communicated by Michael Lindinger. ...
... Part of the large differences in LT can be explained by differences in mitochondrial activity Joyner and Coyle 2008), but we have Communicated by Michael Lindinger. also reported that cyclists with similar mitochondrial activity can still display large differences in % VO 2max at LT (Coyle et al. 1988). This suggests that in addition to mitochondrial activity, other factor(s) might influence the degree of muscle stress and lactate concentration during exercise. ...
Article
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Purpose: The biomechanical differences between cyclists with a high compared with a low blood lactate threshold (HLT; 80% VO2max vs LLT, 70% VO2max) have yet to be completely described. We hypothesize that HLT cyclists reduce the stress placed on the knee extensor muscles by increasing the relative contribution from the hip joint during high-intensity cycling. Method: Sixteen well-trained endurance athletes, with equally high VO2max while cycling and running completed submaximal tests during incremental exercise to identify lactate threshold ([Formula: see text]) while running and cycling. Subjects were separated into two groups based on % VO2max at LT during cycling (high; HLT: 80.2 ± 2.1% VO2max; n = 8) and (LLT: 70.3 ± 2.9% VO2max; n = 8; p < 0.01). Absolute and relative joint specific powers were calculated from kinematic and pedal forces using inverse dynamics while cycling at intensities ranging from 60-90% VO2max for between group comparisons. Result: There was no difference between HLT and LLT in [Formula: see text] (p > 0.05) while running. While cycling in LLT, knee joint absolute power increased with work rate (p < 0.05); however, in HLT no changes in knee joint absolute power occurred with increased work rate (p > 0.05). The HLT generated significantly greater relative hip power compared with the LLT group at 90% VO2max (p < 0.05). Conclusion: These data suggest that HLT cyclists exhibit a greater relative hip contribution to power output during cycling at 90% VO2max. These observations support the theory that lactate production during cycling can be reduced by spreading the work rate between various muscle groups.
... The variation in glycogen use observed in different studies and individuals at the same intensity may be related to the fact that % VO 2max is typically used as the "default" intensity parameter, and this parameter may not necessarily match the metabolic and substrate demands of the effort at the muscular level. Indeed, muscular oxidative capacity can vary greatly between individuals with the same VO 2max (Holloszy 1973;Holloszy and Coyle 1984), and lactate threshold represents a more suitable method for which to match intensity within and between studies (Coyle et al. 1988;Poole et al. 2020). ...
... As such, parameters of training status that are more indicative of the oxidative capacity of skeletal muscle (i.e., lactate threshold) are likely a better parameter for classification of status when determining the effects of training on skeletal muscle glycogen utilization. Indeed, individuals with comparable VO 2max but who possess a "high" or "low" lactate threshold present with distinct differences in glycogen utilization when cycling for 30 min at 80% VO 2max , i.e., subjects with a low threshold utilize more than twice as much muscle glycogen during 30 min exercise (Coyle et al. 1988). ...
Chapter
Muscle glycogen is an important fuel source for contracting skeletal muscle, and it is well documented that exercise performance is impaired when the muscle’s stores of glycogen are exhausted. The role of carbohydrate (CHO) availability on exercise performance has been known for more than a century, while the specific role of muscle glycogen for muscle function has been known for half a century. Nonetheless, the precise cellular and molecular mechanisms by which glycogen availability regulates cell function and contractile-induced fatigue are unresolved. Alterations of pre-exercise muscle glycogen reserves by dietary and exercise manipulations or modifying the degree of dependency on endogenous glycogen during exercise have collectively established a close relationship between muscle glycogen and the resistance to fatigue. It is also apparent that glycogen availability regulates rates of muscle glycogenolysis and resynthesis, muscle glucose uptake, key steps in excitation-contraction coupling, and exercise-induced cell signaling regulating training adaptation. The present review provides both a historical and contemporary overview of the effects of exercise on muscle glycogen metabolism, addressing factors affecting glycogen use during exercise as well as the evolving concepts of how glycogen and glycolysis are integrated with cell function, skeletal muscle fatigue, and training adaptation.KeywordsGlycogenolysis, glycogen particleDietExerciseE-C coupling, fatigue, performance
... As defined by the classical model to predict PO _TT (see Eq. 1), this means that the % V O 2_TT is predicted to be higher if lactate accumulation starts at a higher metabolic rate expressed as a fraction of V O 2max (%VO 2_LT ). However, this model is based on studies that used lactate thresholds (LT) to determine the beginning of blood lactate accumulation (Costill et al. 1973;Allen et al. 1985;Coyle et al. 1988Coyle et al. , 1991. Depending on the threshold concepts and the incremental rate used during exercise tests lactate thresholds under-or overestimate the highest intensity that can be sustained without continuous accumulation of blood lactate during prolonged exercise (Heck et al. 1985;Beneke 1995;Hauser et al. 2013;Jamnick et al. 2018). ...
... It is important to note that the classical model to predict endurance performance (see Eq. 1) is based on studies that used LTs to detect the PO or running speed as well as the corresponding V O 2 values at which BLC starts to accumulate (Costill et al. 1973;Allen et al. 1985;Coyle et al. 1988Coyle et al. , 1991. Interestingly, some of these studies reported strong correlations between % V O 2_LT and % V O 2_TT (Costill et al. 1973;Allen et al. 1985). ...
Article
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Purpose There is no convincing evidence for the idea that a high power output at the maximal lactate steady state (PO_MLSS) and a high fraction of 𝑉˙O2max at MLSS (%𝑉˙O2_MLSS) are decisive for endurance performance. We tested the hypotheses that (1) %𝑉˙O2_MLSS is positively correlated with the ability to sustain a high fraction of 𝑉˙O2max for a given competition duration (%𝑉˙O2_TT); (2) %𝑉˙O2_MLSS improves the prediction of the average power output of a time trial (PO_TT) in addition to 𝑉˙O2max and gross efficiency (GE); (3) PO_MLSS improves the prediction of PO_TT in addition to 𝑉˙O2max and GE. Methods Twenty-one recreationally active participants performed stepwise incremental tests on the first and final testing day to measure GE and check for potential test-related training effects in terms of changes in the minimal lactate equivalent power output (∆PO_LEmin), 30-min constant load tests to determine MLSS, a ramp test and verification bout for 𝑉˙O2max, and 20-min time trials for %𝑉˙O2_TT and PO_TT. Hypothesis 1 was tested via bivariate and partial correlations between %𝑉˙O2_MLSS and %𝑉˙O2_TT. Multiple regression models with 𝑉˙O2max, GE, ∆PO_LEmin, and %𝑉˙O2_MLSS (Hypothesis 2) or PO_MLSS instead of %𝑉˙O2_MLSS (Hypothesis 3), respectively, as predictors, and PO_TT as the dependent variable were used to test the hypotheses. Results %𝑉˙O2_MLSS was not correlated with %𝑉˙O2_TT (r = 0.17, p = 0.583). Neither %𝑉˙O2_MLSS (p = 0.424) nor PO_MLSS (p = 0.208) did improve the prediction of PO_TT in addition to 𝑉˙O2max and GE. Conclusion These results challenge the assumption that PO_MLSS or %𝑉˙O2_MLSS are independent predictors of supra-MLSS PO_TT and %V˙O2_TT.
... Exercise intensity was analyzed as a percentage of VO 2max because that is the most widely reported unit in exercise science. This can be problematic because substrate use can vary greatly at a given percentage of VO 2max depending on whether someone has a high or low lactate threshold [34,140]. Therefore, the use of lactate or ventilatory thresholds could be a better reference for exercise intensity [141], and/or could also be included as a model variable in future regression analysis. ...
... As an alternative measure of fitness status, training age (i.e., number of years performing regular endurance training) could help to explain some of the variability in RER during exercise but was not included in the models due to the limited number of studies reporting this value. An increased training age could be expected to accompany longer-term training adaptations such as an increased lactate threshold and/or higher percentage of type I muscle fibers [34]. Taken together, fitness level, most easily quantified as VO 2max , likely has a small yet significant negative influence on RER, but other factors may be more predictive of RER during exercise. ...
Article
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Background: Multiple factors influence substrate oxidation during exercise including exercise duration and intensity, sex, and dietary intake before and during exercise. However, the relative influence and interaction between these factors is unclear. Objectives: Our aim was to investigate factors influencing the respiratory exchange ratio (RER) during continuous exercise and formulate multivariable regression models to determine which factors best explain RER during exercise, as well as their relative influence. Methods: Data were extracted from 434 studies reporting RER during continuous cycling exercise. General linear mixed-effect models were used to determine relationships between RER and factors purported to influence RER (e.g., exercise duration and intensity, muscle glycogen, dietary intake, age, and sex), and to examine which factors influenced RER, with standardized coefficients used to assess their relative influence. Results: The RER decreases with exercise duration, dietary fat intake, age, VO2max, and percentage of type I muscle fibers, and increases with dietary carbohydrate intake, exercise intensity, male sex, and carbohydrate intake before and during exercise. The modelling could explain up to 59% of the variation in RER, and a model using exclusively easily modified factors (exercise duration and intensity, and dietary intake before and during exercise) could only explain 36% of the variation in RER. Variables with the largest effect on RER were sex, dietary intake, and exercise duration. Among the diet-related factors, daily fat and carbohydrate intake have a larger influence than carbohydrate ingestion during exercise. Conclusion: Variability in RER during exercise cannot be fully accounted for by models incorporating a range of participant, diet, exercise, and physiological characteristics. To better understand what influences substrate oxidation during exercise further research is required on older subjects and females, and on other factors that could explain additional variability in RER.
... Only by using meticulous methodology in the laboratory, authors such as Coyle, Coggan, Hopper, & Walters (1988), were able to assert that the position of the first ventilatory threshold with respect to the VO2max intensity allows to estimate the greater or lesser durability until exhaustion of a cyclist or athlete (i.e., the closer the first threshold is respect to the VO2max, the higher is the TTE at VO2max intensity). Likewise, unpublished data extracted from the research works link with the doctoral thesis of Lillo-Beviá, J.R. (2019), show evidence in cyclists of the inverse correlation between the position of either the Second Ventilatory Threshold (VT2) or the Maximal Lactate Steady State (MLSS) intensities, with respect to the Maximal Oxygen Consumption (VO2max) intensity, as an indicator of the TTE at VO2max intensity (ie, the closer the MLSS or VT2 is to VO2max, the higher is the TTE at the latter intensity). ...
... How long it is a cyclist able to keep pedalling at a certain intensity is inversely Page 2 proportional to this intensity. The relationship between power or speed and time to exhaustion has been repeatedly analysed in the scientific literature since the early 1990s and even earlier (Billat et al., 1996;Veronique Billat, Renoux, Pinoteau, Petit, & Koralsztein, 1994;Coyle, Coggan, Hemmert, & Ivy, 1986;Coyle et al., 1988;Billat et al., 1996). To provide information to the readers of this article, some summarizing tables were published in this author's doctoral thesis (Lillo Beviá, 2019), where between-subject, but also within-subject variability were described. ...
Article
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It seems sensible to establish that TTE in laboratories for each cyclist and for each specific physiologic event, involves a very high cost in human resources, time, and materials, as well as been highly demanding for cyclists from the physiological and physiological point of view. These facts preclude its widespread use for most of them. However, it is also evident that although the use of potentiometers in the field and the analysis of power profiles based on specific times represent the future, it must be recognized that, without the basic research carried out in laboratories around the world during the last three decades, this future would lack of the sufficient scientific support
... It is tempting to suggest that as a result of the inverse relationship between lactate and fat oxidation (San-Millán and Brooks, 2018), excessive HIIT and concomitant lactate accumulation performed chronically could hinder optimizing fat oxidation. While some HIIT vs. MICT studies show similar acute molecular signaling and enzyme adaptations (Gibala et al., 2006;Burgomaster et al., 2008), earlier work has suggested that mitochondrial enzymes alone are not indicative of exercise metabolism or endurance performance in highly trained athletes (Coyle et al., 1988). As reported in a review by MacInnis and Gibala, the similar responses are likely attributed to greater metabolic stress via increased ATP turnover, reactive oxygen species (ROS), Ca2+-calmodulin-dependent protein kinase II (CaMKII) signaling, and intracellular metabolite accumulation (lactate, AMP, ADP) in HIIT trials that may compensate for reduced training volume during MICT (Macinnis and Gibala, 2017). ...
... Interestingly, Coyle and colleagues work on two groups of competitive cyclists matched for fitness and with similar mitochondrial enzyme activity (citrate synthase and βhydroxyacyl-CoA dehydrogenase) demonstrated markedly different time-to-exhaustion performance, post-exercise lactate, % VO 2 max at lactate threshold, and capillary density (Coyle et al., 1988). Both of the aforementioned enzymes have been previously measured to compare metabolic adaptations between HIIT and MICT (Burgomaster et al., 2008). ...
... Maximal aerobic capacity ( V O 2 max ) is a well-established marker of cardio-respiratory fitness and related to longterm health outcomes [1][2][3], predicting longevity in a dose-response-dependent manner, alongside numerous other phenotypic changes [4]. In addition to the 'protective' health effects ascribed to cardiorespiratory fitness [5], V O 2 max is also a primary determinant of endurance performance, explaining ~ 20-60% of the variation in performances of different mode and distance, which can be realised by athletes when combined with other sub-maximal endurance performance determinants [6][7][8]. Despite the suggested limited trainability of V O 2 max [9], a number of different training approaches have been adopted to support its adaptation, such as repeated high-intensity or continuous endurance exercise, which typically confers moderate effects [10]. ...
... These were cross-checked for agreement. Seven assessment criteria were used to assess for risk of bias under the Cochrane Review criteria [36]: (1) sequence generation, (2) allocation concealment, (3) blinding of participants, (4) blinding of outcome data, (5) incomplete outcome data, (6) selective outcome reporting, and (7) other sources of bias. Each assessment criterion was judged by the review authors under three classifications, "Yes" to indicate low risk of bias, "No" to indicate high risk of bias and finally, "Unclear" to indicate level of bias is unclear or not known (Fig. 2). ...
Article
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Background Heat acclimation and acclimatisation (HA) is typically used to enhance tolerance to the heat, thereby improving performance. HA might also confer a positive adaptation to maximal oxygen consumption ( $$V{\text{O}}_{2\max }$$ V O 2 max ), although this has been historically debated and requires clarification via meta-analysis. Objectives (1) To meta-analyse all studies (with and without control groups) that have investigated the effect of HA on $$V{\text{O}}_{2\max }$$ V O 2 max adaptation in thermoneutral or hot environments; (2) Conduct meta-regressions to establish the moderating effect of selected variables on $$V{\text{O}}_{2\max }$$ V O 2 max adaptation following HA. Methods A search was performed using various databases in May 2020. The studies were screened using search criteria for eligibility. Twenty-eight peer-reviewed articles were identified for inclusion across four separate meta-analyses: (1) Thermoneutral $$V{\text{O}}_{2\max }$$ V O 2 max within-participants (pre-to-post HA); (2) Hot $$V{\text{O}}_{2\max }$$ V O 2 max within-participants (pre-to-post HA); (3) Thermoneutral $$V{\text{O}}_{2\max }$$ V O 2 max measurement; HA vs . control groups; (4) Hot $$V{\text{O}}_{2\max }$$ V O 2 max measurement, HA vs . control groups. Meta-regressions were performed for each meta-analysis based on: isothermal vs . iso-intensity programmes, days of heat exposure, HA ambient temperature (°C), heat index, HA session duration (min), ambient thermal load (HA session x ambient temperature), mean mechanical intensity (W) and the post-HA testing period (days). Results The meta-analysis of pre–post differences in thermoneutral $$V{\text{O}}_{2\max }$$ V O 2 max demonstrated small-to-moderate improvements in $$V{\text{O}}_{2\max }$$ V O 2 max (Hedges’ g = 0.42, 95% CI 0.24–0.59, P < 0.001), whereas moderate improvements were found for the equivalent analysis of hot $$V{\text{O}}_{2\max }$$ V O 2 max changes (Hedges’ g = 0.63, 95% CI 0.26–1.00, P < 0.001), which were positively moderated by the number of days post-testing ( P = 0.033, β = 0.172). Meta-analysis of control vs . HA thermoneutral $$V{\text{O}}_{2\max }$$ V O 2 max demonstrated a small improvement in $$V{\text{O}}_{2\max }$$ V O 2 max in HA compared to control (Hedges’ g = 0.30, 95% CI 0.06–0.54, P = 0.014) and this effect was larger for the equivalent hot $$V{\text{O}}_{2\max }$$ V O 2 max analysis where a higher ( moderate-to-large ) improvement in $$V{\text{O}}_{2\max }$$ V O 2 max was found (Hedges’ g = 0.75, 95% CI 0.22–1.27, P = 0.005), with the number of HA days ( P = 0.018; β = 0.291) and the ambient temperature during HA ( P = 0.003; β = 0.650) positively moderating this effect. Conclusion HA can enhance $$V{\text{O}}_{2\max }$$ V O 2 max adaptation in thermoneutral or hot environments, with or without control group consideration, by at least a small and up to a moderate–large amount, with the larger improvements occurring in the heat. Ambient heat, number of induction days and post-testing days can explain some of the changes in hot $$V{\text{O}}_{2\max }$$ V O 2 max adaptation.
... It refers to the highest MPO maintained in a quasi-steady state for 60 min (FTP 60 ) without the onset of fatigue [16]. FTP has demonstrated its validity as a surrogate for lactate threshold (LT) [17] and maximum lactate steady state (MLSS) [18,19]. LT is defined as the maximum intensity preceding an exponential rise in blood lactate values during an incremental test [20], being addressed that during a continuous effort at LT blood lactate concentration steadily rises [17]. ...
... FTP has demonstrated its validity as a surrogate for lactate threshold (LT) [17] and maximum lactate steady state (MLSS) [18,19]. LT is defined as the maximum intensity preceding an exponential rise in blood lactate values during an incremental test [20], being addressed that during a continuous effort at LT blood lactate concentration steadily rises [17]. However, MLSS refers to the maximum workload that can be maintained over time without continual blood lactate accumulation (i.e., 45-70 min) [18,21]. ...
Article
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Wearable technology has allowed for the real-time assessment of mechanical work employed in several sporting activities. Through novel power metrics, Functional Threshold Power have shown a reliable indicator of training intensities. This study aims to determine the relationship between mean power output (MPO) values obtained during three submaximal running time trials (i.e., 10 min, 20 min, and 30 min) and the functional threshold power (FTP). Twenty-two recreationally trained male endurance runners completed four submaximal running time trials of 10, 20, 30, and 60 min, trying to cover the longest possible distance on a motorized treadmill. Absolute MPO (W), normalized MPO (W/kg) and standard deviation (SD) were calculated for each time trial with a power meter device attached to the shoelaces. All simplified FTP trials analyzed (i.e., FTP10, FTP20, and FTP30) showed a significant association with the calculated FTP (p < 0.001) for both MPO and normalized MPO, whereas stronger correlations were found with longer time trials. Individual correction factors (ICF% = FTP60/FTPn) of ~90% for FTP10, ~94% for FTP20, and ~96% for FTP30 were obtained. The present study procures important practical applications for coaches and athletes as it provides a more accurate estimation of FTP in endurance running through less fatiguing, reproducible tests.
... simply be to maintain the already expansive capillary network. Any means of further expanding is likely to have an important role given the close correlations between capillary supply and exercise capacity (Saltin et al. 1977;Coyle et al. 1988;Mitchell et al. 2018). ...
Article
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Exercise-induced skeletal muscle angiogenesis is a well-known physiological adaptation that occurs in humans in response to exercise training and can lead to endurance performance benefits, as well as improvements in cardiovascular and skeletal tissue health. An increase in capillary density in skeletal muscle improves diffusive oxygen exchange and waste extraction, and thus greater fatigue resistance, which has application to athletes but also to the general population. Exercise-induced angiogenesis can significantly contribute to improvements in cardiovascular and metabolic health, such as the increase in muscle glucose uptake, important for the prevention of diabetes. Recently, our understanding of the mechanisms by which angiogenesis occurs with exercise has grown substantially. This review will detail the biochemical, cellular and biomechanical signals for exercise-induced skeletal muscle angiogenesis, including recent work on extracellular vesicles and circulating angiogenic cells. In addition, the influence of age, sex, exercise intensity/duration, as well as recent observations with the use of blood flow restricted exercise, will also be discussed in detail. This review will provide academics and practitioners with mechanistic and applied evidence for optimising training interventions to promote physical performance through manipulating capillarisation in skeletal muscle.
... The first threshold encountered during incremental exercise is the lactate threshold (LT; defined as 1 mmol·L -1 increase above baseline) (Coyle et al. 1988). The relative intensity at which the LT occurs represents an individual's metabolic fitness and endurance training status (Jones 2006). ...
Conference Paper
Introduction: Functional threshold power (FTP) is the endurance performance measure adopted by cyclists which estimates maximum power output for one hour. Training zones are derived as fractions of FTP with supposed correlations to blood lactate ([bLa]). However, little physiological evidence exists to support FTP and its training zones. Methods: Ten recreationally to moderately trained cyclists performed a maximal test to determine peak oxygen uptake (V̇ O2peak: 51.9 ± 7.4 ml·min-1 ·kg-1 ) and maximal aerobic power (MAP; 335 ± 59 W), three time trials (TT - 3, 8 and 12 min) and three constant-load trials to exhaustion (TTE) for determination of critical power (CP) from two trial formats (TT: 240 ± 41 W; TTE: 251 ± 49 W). A sub-maximal test determined lactate threshold (LT; 192 ± 41 W) and [bLa] = 4.0 mmol.L-1 ([bLa]4; 229 ± 43 W), and a 20 min TT provided the FTP estimate (236 ± 45 W). Participants performed one final TTE trial at FTP (45 ± 12 min). Results: FTP was not different to CP-TT (P = 1.000), CP-TTE (P = 0.216), or [bLa]4 (P = 1.000), and positively correlated to CP-TT (r = 0.98, P < 0.01), CP-TTE (r = 0.97, P < 0.01), and [bLa]4 (r = 0.85, P < 0.01). Discussion: These data reveal strong positive correlations of FTP with CP and [bLa]4 which substantiates previous literature supporting FTP as a single test estimate of endurance performance and CP. Take home message: An alternative model of FTP training zones based on LT, CP, and MAP was created with increased physiological validity.
... Thus cyclists require excellent aerobic and anaerobic capacities . The physical and physiological demands placed on cyclists have been described elsewhere (Coyle et al., 1988(Coyle et al., , 1991Krebs et al., 1986;. Briefly, these previous studies have reported that relative VO 2 max values normally range between 69 and 85 ml/kg/min, with concomitant power output at VO 2 max of ∼6.7 W·kg −1 . ...
Article
Purpose Certain anthropometric characteristics are required for athletes to successfully perform in elite endurance sports. The present study aims to analyse the anthropometric characteristics of professional cyclists according to their specialty. Method Anthropometric measurements were conducted of the body composition of seventy-six male professional road cyclists in line with International Society for Advancement of Kinanthropometry protocol. Results Fat mass did not differ (p > 0.05) between climbers, all-rounders and flat specialists, although the following anthropometric variables did differ according to the role played within the team (p < 0.05): Body mass (climbers: 63.8 ± 3.6, all-rounders: 68.8 ± 5.3, flat specialists: 74.5 ± 5.6 kg) skeletal body mass (climbers: 29.7 ± 1.6, all-rounders: 31.4 ± 1.9, flat specialists: 33.5 ± 2.4 kg); body surface area (climbers: 1.78 ± 0.07, all-rounders: 1.89 ± 0.10, flat specialists: 1.96 ± 0.1 m²); frontal area (climbers: 0.33 ± 0.01, all-rounders: 0.35 ± 0.02, flat specialists: 0.36 ± 0.02 m²). Conclusions Anthropometric characteristic differ between world-class cyclists depending on their specialty. These differences could influence performance in relation to different types of road cycling competitions. The present study identified characteristics which could be used by coaches to evaluate their athletes in the context of elite or professional road cycling.
... While some sex comparisons were made, our study was not specifically powered to compare data between males and females; therefore, these comparisons should be viewed as exploratory analyses. The present study investigated limitations to MLSS by manipulating O 2 transport; however, peripheral factors also seem to play an important role in exercise thresholds (Beever et al., 2020;Coyle et al., 1988;Iannetta et al., 2019;Ivy et al., 1980;Mitchell et al., 2018), and future studies should consider these factors when investigating limitations to MLSS. Finally, our experiment was conducted at a mild altitude (∼1100 m), which could influence the generalizability to sea-level conditions. ...
Article
New findings: What is the central question of this study? What is the effect of an elevated COHb concentration following carbon monoxide inhalation on the maximal lactate steady state (MLSS) in humans and is this effect dependent on aerobic fitness? What is the main finding and its importance? An elevated COHb concentration intensified physiological responses to exercise at the MLSS- including heart rate, ventilation, and peripheral fatigue-in all participants and reduced the MLSS (i.e., destabilized the blood lactate concentration) in trained but not untrained males and females. Abstract: This study investigated whether a lower effective [Hb], induced by carbon monoxide (CO) inhalation, reduces the peak oxygen uptake (V̇O2 peak) and the maximal lactate steady state (MLSS) and whether training status explains individual variation in these impairments. Healthy young participants completed two ramp incremental tests (n = 20 [10 female]) and two trials at MLSS (n = 16 [8 female]) following CO rebreathe tests and sham procedures (SHAM) in random orders. All fitness variables were normalized to fat-free mass (FFM) to account for sex-related differences in body composition, and males and females were matched for aerobic fitness. The V̇O2 peak (mean [SD]: -4.2 [3.7]%), peak power output (-3.3 [2.2]%), and respiratory compensation point (-6.3 [4.5]%) were reduced in CO compared with SHAM (P < 0.001 for all), but the gas exchange threshold (-3.3 [7.1]%) was not (P = 0.077). Decreases in V̇O2 peak (r = -0.45; P = 0.047) and peak power output (r = -0.49; P = 0.029) in CO were correlated with baseline aerobic fitness. Compared to SHAM, physiological and perceptual indicators of exercise-related stress were exacerbated by CO while cycling at MLSS. Notably, the mean blood lactate concentration ([La]) increased (i.e., Δ[La] > 1.0 mM) between 10 min (5.5 [1.4] mM) and 30 min (6.8 [1.3] mM; P = 0.026) in CO, with 9/16 participants classified as unstable. These unstable participants had a higher V̇O2 peak (66.2 [8.5] vs. 56.4 [8.8] mL·kg FFM-1 ·min-1 , P = 0.042) and V̇O2 at MLSS (55.8 vs. 44.3 mL·kg FFM-1 ·min-1 , P = 0.006) compared to the stable group. In conclusion, a reduced O2 -carrying capacity decreased maximal and submaximal exercise performance, with higher aerobic fitness associated with greater impairments in both. This article is protected by copyright. All rights reserved.
... Critical power measured in this manner has been shown to discriminate heavy and severe-intensity exercise responses, and therefore estimate the MMSS (Jones et al. 2008;Black et al. 2017). Work output at the MMSS is used in training intensity regulation, training load monitoring, and predicting endurance performance (Coyle et al. 1988;Maunder et al. 2021). ...
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Purpose: The three-minute all-out test (3MT), when performed on a laboratory ergometer in a linear mode, can be used to estimate the heavy-severe-intensity transition, or maximum metabolic steady state (MMSS), using the end-test power output. As the 3MT only requires accurate measurement of power output and time, it is possible the 3MT could be used in remote settings using personal equipment without supervision for quantification of MMSS. Methods: The aim of the present investigation was to determine the reliability and validity of remotely performed 3MTs (3MTR) for estimation of MMSS. Accordingly, 53 trained cyclists and triathletes were recruited to perform one familiarisation and two experimental 3MTR trials to determine its reliability. A sub-group (N = 10) was recruited to perform three-to-five 30 min laboratory-based constant-work rate trials following completion of one familiarisation and two experimental 3MTR trials. Expired gases were collected throughout constant-work rate trials and blood lactate concentration was measured at 10 and 30 min to determine the highest power output at which steady-state [Formula: see text] (MMSS-[Formula: see text]) and blood lactate (MMSS-[La-]) were achieved. Results: The 3MTR end-test power (EPremote) was reliable (coefficient of variation, 4.5% [95% confidence limits, 3.7, 5.5%]), but overestimated MMSS (EPremote, 283 ± 51 W; MMSS-[Formula: see text], 241 ± 46 W, P = 0.0003; MMSS-[La-], 237 ± 47 W, P = 0.0003). This may have been due to failure to deplete the finite work capacity above MMSS during the 3MTR. Conclusion: These results suggest that the 3MTR should not be used to estimate MMSS in endurance-trained cyclists.
... Skeletal muscle capillarization is a central determinant of oxygen and nutrient delivery, and removal of metabolites in skeletal muscle (1) with important implications for health (2)(3)(4) and exercise performance (5,6). Accordingly, muscle capillarization is essential for insulin sensitivity (2)(3)(4) and appears to be linked with both whole body maximal oxygen uptake (7) and critical power training for populations ranging from sedentary individuals to world class athletes, as well as for rehabilitation after immobilization or bedrest in patients and athletes. ...
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Purpose: To investigate the effect of intensity and duration of continuous and interval exercise training on capillarization in skeletal muscle of healthy adults. Methods: PubMed and Web of Science were searched from inception to June 2021. Eligibility criteria for studies were: endurance exercise training >2 wks in healthy adults, and capillary to fiber ratio (C:F) and/or capillary density (CD) reported. Meta-analyses were performed and subsequent subgroup analyses were conducted by the characteristics of participants and training scheme. Results: 57 trials from 38 studies were included (10/90%, athletic/sedentary). C:F was measured in 391 subjects from 47 trials while CD was measured in 428 subjects from 50 trials. Exercise training increased C:F (Mean difference (MD) 0.33 [0.30-0.37; 95% CI]) with low heterogeneity (I2 = 45.08 %) and CD (MD 49.8 [36.9-62.6] Cap/mm2) with moderate heterogeneity (I2 = 68.82%). Compared to low intensity training (LOW, <50% of VO2max), 21% higher relative change in C:F ratio was observed after continuous moderate intensity training (CON, 50-80%VO2max) and 54% higher change after interval training with high intensity (INT, 80-100% of VO2max) in sedentary subjects. The magnitude of capillary growth was not dependent on training intervention duration. In already trained subjects, no additional increase in capillarization was observed with various types of training. Conclusions: In sedentary subjects, CON and INT leads to increases in capillarization, whereas LOW has less effect. Within the timeframe studied, no effect on capillarization was established regarding training duration in sedentary subjects. The meta-analysis highlights the need for further studies in athlete groups to discern if increased capillarization can be obtained, and if so, which combination is optimal (time vs intensity).
... In addition, female athletes maintained a velocity corresponding to 75% of the MAV during the running split, which is higher than the value for males, who maintained 62% of their MAV [34]. The VT is limited by the peripheral conditions (i.e., mitochondrial volume, capillary density, oxidative enzyme capacity) [45,46]. Considering this context, females present different metabolic (greater proportional area of type I fibers [22][23][24], greater whole-muscle oxidative capacity [26], and greater mitochondrial oxidative function [28]), contractile (Ca 2+ transients were smaller in magnitude and longer in duration in females [47]), and hemodynamic (greater vasodilatory responses of the arteries to muscles and higher density of capillaries per unit of skeletal muscle [22]) properties of skeletal muscles than males, favoring ATP resynthesis from oxidative phosphorylation during exercise [48,49], which could contribute to a higher VT. ...
Article
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Sex differences in triathlon performance have been decreasing in recent decades and little information is available to explain it. Thirty-nine male and eighteen female amateur triathletes were evaluated for fat mass, lean mass, maximal oxygen uptake (VO2 max), ventilatory threshold (VT), respiratory compensation point (RCP), and performance in a national Olympic triathlon race. Female athletes presented higher fat mass (p = 0.02, d = 0.84, power = 0.78) and lower lean mass (p < 0.01, d = 3.11, power = 0.99). VO2 max (p < 0.01, d = 1.46, power = 0.99), maximal aerobic velocity (MAV) (p < 0.01, d = 2.05, power = 0.99), velocities in VT (p < 0.01, d = 1.26, power = 0.97), and RCP (p < 0.01, d = 1.53, power = 0.99) were significantly worse in the female group. VT (%VO2 max) (p = 0.012, d = 0.73, power = 0.58) and RCP (%VO2 max) (p = 0.005, d = 0.85, power = 0.89) were higher in the female group. Female athletes presented lower VO2 max value, lower lean mass, and higher fat mass. However, females presented higher values of aerobic endurance (%VO2 max), which can attenuate sex differences in triathlon performance. Coaches and athletes should consider that female athletes can maintain a higher percentage of MAV values than males during the running split to prescribe individual training.
... The maximal oxygen uptake (VO 2 max) is a well-known marker of cardiorespiratory fitness and is associated with good health outcomes [3]. In addition to the "protective" health effects attributed to cardiorespiratory fitness [4], VO 2 max is also the primary determinant of endurance capacity, explaining about 20-60% of the variability in performance with different modes and distances, which can be achieved by athletes in combination with other determinants of maximum endurance capacity [5,6]. ...
Article
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The purpose of the study was to assess the impact of training on the physiological variables achieved during the test effort in the macrocycle of road cyclists and their use in the maximal oxygen uptake (VO2max) prediction at individual training stages in the VO2max test. Nine well-trained male cyclists (age 25.6 ± 5.2 years and body weight 72.4 ± 7.35 kg) participated in the study and each phase of the macrocycle was followed by a time to exhaustion test (TTE) on the bicycle ergometer. The research showed that training loads significantly influence the maximum power (PPO), ventilation (VE) in the preparatory period (T1), time of the test (TTmax) at the start of the competition period (T2), percentage of body fat in total body weight (%FAT) and skeletal muscle mass (MMS) during the competition period (T3). Of the 16 variables taken for the analysis of the principal components (PC), the regression model determined one principal variable responsible for VO2max in the training macrocycle of cyclists, the relative value of maximum power (PPORV) and the accompanying variables in individual periods: breathing frequency (BF), delta blood lactate concentration (ΔLA), body fat (FAT) and MMS. Determining PC influencing the exercise capacity can be crucial in achieving the intended goals by athletes. Monitoring these indicators can help protect the health of professional athletes and provide guidelines in the training process, stimulate the body properly while protecting against overtraining.
... Differences in actual performance between athletes may therefore be related to additional factors (12). First, exercise economy/efficiency; this parameter describes how well oxygen is converted into locomotion at submaximal intensities and has been shown to be significantly different between groups with nonsignificant differences in V _ O 2max (13). ...
... The moderate intensity domain refers to intensities below the so-called first lactate threshold, defined as the intensity after which there is a sustained increase in blood lactate concentration above resting values (LT1). 19,20 This domain is characterized by a steady state cardiopulmonary response and little or no sustained increase in blood lactate concentration. The heavy intensity domain refers to intensities above LT1, but below critical power, which is analogous to the socalled second lactate threshold when there is a second rise in blood lactate concentration above resting levels (LT2). ...
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Purpose The desire-goal motivational conflict helps explain endurance performance, however, the physiological concomitants are unknown. The present study examined disturbances in desire to reduce effort and performance goal value across moderate, heavy, and severe exercise intensity domains, demarcated by the first (LT1) and second (LT2) lactate thresholds. In addition, the within-person relationships between blood lactate concentration, heart rate and desire-goal conflict were examined. Methods Thirty participants (53% female, Mage = 21.03 years; SD = 2.06 years) completed an incremental cycling exercise test, in which work-rate was increased by 25 watts every four minutes, until voluntary exhaustion or sufficient data from the severe intensity domain had been collected. Desire to reduce effort, performance goal value, blood lactate concentration (for determination of LT1 and LT2) and heart rate were measured at the end of each stage and analyzed using multilevel models. Results The desire to reduce effort increased over the exercise test with additional shifts and accelerations after each lactate threshold. The performance goal did not show general declines, nor did it shift at LT1. However, the performance goal value shifted at LT2, and the rate of change increased at both thresholds. Within-person variation in blood lactate concentration positively correlated with the desire to reduce effort and negatively correlated with the performance goal. Within-person variation in heart rate correlated with desire to reduce effort but not the performance goal. Conclusion Transitioning through both lactate thresholds are important phases for motivation during progressive exercise, particularly for the desire to reduce effort. Within-person variation in blood lactate concentration is more influential for motivation, compared to heart rate.
... Its assessment is a common practice in sports of medium and long duration such as long-distance running, road cycling, long-distance swimming and team games (18). Although a high VO2max is generally considered as a prerequisite for competing on a high level in endurance exercise, athletes with similar maximal aerobic capacity can still display different performance results and great variability in time to fatigue even if performing at the same rate and percentage of VO2max (19) (20). It should be realised, though, that next to a high aerobic capacity, the good ability to sustain short periods of intense anaerobic exercise with concomitant high lactate levels is required to be distinctive and to win races. ...
Thesis
BACKGROUND During high-intensity exercises, such as cycling sprints or interval training, the high and instantaneous demand for energy causes an exponential blood accumulation of metabolites (Pi, H+, La-), causing a decrease in blood and muscle pH. This coincides with perceived muscle fatigue and performance decline. Profound fluctuations in pH are commonly prevented by so-called buffer systems. In skeletal muscle, the most extensively researched buffer system is sodium bicarbonate. Thus, the increased capacity of the sodium bicarbonate buffer system has been suggested to be the most effective in improving exercise performance, especially in short-term intense exercise. However, little research has been conducted on the effects of exogenous sodium bicarbonate supplementation on changes in blood lactate levels during intense (progressive) exercise and subsequent recovery. Therefore, this study aims to investigate the influence of sodium bicarbonate supplementation on blood lactate levels during a cycling test to exhaustion and its effect on cycling performance. METHODS 10 elite cyclists, 6 men and 4 women, from the professional cycling team ‘Team DSM’ underwent a double-blinded, cross-over, randomized controlled trial. Athletes were allocated to two intervention groups: oral ingestion of 0.3g·Kg-1 body mass of sodium bicarbonate or 0.07g·Kg-1 of sodium chloride (placebo). Two hours after the ingestion, participants performed an incremental cycling test until exhaustion. Blood lactate, heart rate, relative perceived exertion and rate of gastrointestinal discomfort were recorded, while the time to exhaustion was considered as a performance parameter. Analysis of variance, paired t-test and two-way ANOVA were applied to compare variables across condition. Stratified analyses were performed for sprinter and general classification athletes and for gender. RESULTS No difference between sodium bicarbonate and placebo conditions was found for maximum blood lactate (mean ±SD 11.4±5.6 mmol/L vs 9.8±4.6 mmol/L, p= 0.5), maximum heart rate (mean±SD 185.3±10.9 bpm vs 180.9±10.2 bpm, p= 0.6) and relative perceived exertion (mean±SD 13.1±0.9 vs 13.5 vs 0.6, p=0.2). The performance parameter did not improve significantly with sodium bicarbonate supplementation (time to exhaustion = mean ±SD 52.7±6.9 min vs 53.3±6.9 min, p=0.8). Sprinter cyclists showed higher blood lactate (mean±SD +1.73 ± 3.5 mmol/L) and higher maximal blood lactate (mean ±SD +6.3±3.7 mmol/L) compared to general classification athletes under sodium bicarbonate condition than under placebo condition. No difference across gender was found. CONCLUSIONS Our results indicate that sodium bicarbonate does not significantly affect maximum blood lactate, maximum heart rate, relative perceived exertion, and performance parameters in a stepwise incremental test in elite cyclists. However, stratified analyses revealed that 0.3g·Kg-1 of sodium bicarbonate increase more blood lactate levels in sprint cyclists than in general classification cyclists compared to placebo.
... Cyclists are required to maintain high levels of sustainable power while also being able to generate peak force and power very quickly for short periods of time followed by various durations of steady-state recovery work for success. Previous research shows the primary determinants of endurance cycling performance include peak oxygen uptake, peak power output, gross efficiency, and numerous lactate markers representing distinct changes in aerobic metabolism (Coyle et al., 1988). Interestingly, as stated above, nitrate supplementation enhances many of these cycling related performance areas. ...
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Introduction This study investigated the effects of a beet nitric oxide enhancing (NOE) supplement comprised of nitrite and nitrate on cycling performance indices in trained cyclists. Methods: Subjects completed a lactate threshold test and a high-intensity interval (HIIT) protocol at 50% above functional threshold power with or without oral NOE supplement. Results: NOE supplementation enhanced lactate threshold by 7.2% (Placebo = 191.6 ± 37.3 watts, NOE = 205.3 ± 39.9; p =0.01; Effect Size (ES) = 0.40). During the HIIT protocol, NOE supplementation improved time to exhaustion 18% (Placebo = 1,251 ± 562s, NOE = 1,474 ± 504s; p = 0.02; ES = 0.42) and total energy expended 22.3% (Placebo = 251 ± 48.6 kJ, NOE = 306.6 ± 55.2 kJ; p = 0.01; ES = 1.079). NOE supplementation increased the intervals completed (Placebo = 7.00 ± 2.5, NOE = 8.14 ± 2.4; p = 0.03; ES = 0.42) and distance cycled (Placebo = 10.9 ± 4.0 km, NOE = 13.5 ±3.9 km; p = 0.01; ES = 0.65). Also, target power was achieved at a higher cadence during the HIIT work and rest periods (p=0.02), which enhanced muscle oxygen saturation (SmO2) recovery. Time-to-fatigue was negatively correlated with the degree of SmO2, desaturation during the HIIT work interval segment (r = -0.67; p 0.008), while both SmO2 desaturation and the SmO2 starting work segment saturation level correlated with a cyclist’s kJ expended (SmO2 desaturation: r = -0.51, p = 0.06; SmO2 starting saturation: r = 0.59, p = 0.03). Conclusion: NOE supplementation containing beet nitrite and nitrate enhanced submaximal (lactate threshold) and HIIT maximal effort work. The NOE supplementation resulted in a cyclist riding at higher cadence rates with lower absolute torque values at the same power during both the work and rest periods, which in-turn delayed over-all fatigue and improved total work output.
... Conversely, an even shorter mean difference (~ 15-25 s) in time sustained above 85 %V O 2 max was detected as statistically different when investigating the influence of pacing strategy on interval training in trained cyclists [4], while a difference superior to 60 s was not different in well-trained skiers [9]. Some aspects may help to explain these divergent results, such as individual variability in tV O 2 max [19] or in fractional utilization of V O 2 max at the lactate threshold [20]. In addition, there was a risk of a type II error in this study due to the small sample size. ...
Article
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The current study aimed to compare time spent above 90% V̇O2max (tV̇O2max) during 3 work-matched interval training protocols comprising 8 x 60-second exercise efforts with decreasing, increasing, or constant work rate distribution within each exercise interval. Ten healthy male subjects (age: 27.6 ± 5.0 years; V̇O2max: 3.82 ± 0.52 L•min-1) performed an incremental test to determine V̇O2max and peak power output (Pmax). During visits 2, 3, and 4, three work-matched interval training sessions comprising 8 x 60 s efforts: 60 s active recovery with the power output held constant (100%Pmax; ITCON), decreasing (from 110 to 90%Pmax; ITDEC), or increasing (from 90 to 110%Pmax; ITINC) linearly throughout each work interval. Time sustained above 90% of V̇O2max (tV̇O2max) or HRmax (tHRmax), blood lactate concentrations (BLC) and rating of perceived exertion (RPE) were measured. The tV̇O2max (ITCON: 274 ± 132; ITDEC: 313 ± 102; ITINC: 310 ± 113 s, P = 0.37), tHRmax (ITCON: 396 ± 180; ITDEC: 441 ± 207; ITINC: 390 ± 212 s, P = 0.47), BLC (P = 0.73), and final RPE (P = 0.75) were similar among protocols. In conclusion, work-matched interval training induced similar time near V̇O2max and associated physiological responses regardless of work rate manipulation.
... Some studies have found higher %VO 2MAX in VT2 or lactate threshold in AMA compared to lower fitness level participants [12,47]. In PRO, high values of VT2 (~90% of VO 2MAX ) have been documented, similar to those found in our study [7]. ...
Article
Currently, there are no studies that compares bone condition markers between professional (PRO) and amateur (AMA) cyclists. Amateur cyclists are the ones who practice this sport the most. Therefore, there is an interest in behaving if there is a negative effect at the bone level could be similar than previously described in professional cyclists. The aim of this study was to identify the differences in bone level between professional and amateur road cyclists, and to see if the differences found are related to differences in performance. A parallel trial was carried out with 15 AMA and 10 PRO cyclists. All cyclists performed 2 visits: 1) in a fasted state, body composition with measured by densitometry (DEXA) was analyzed and 2) physiological variables were measured using an incremental test until exhaustion. Significantly lower values were found in bone mineral density, bone mineral content and fat free mass in PRO compared to AMA (p<0.05). In addition, significantly higher power produced in ventilatory thresholds 1 and 2 (VT1 and VT2) and VO2MAX were found in PRO compared to AMA (p<0.05). PRO cyclists present lower values in bone health and muscle mass markers but better results in performance compared to AMA.
... 27 Another study reported a large intra-subject variability in blood lactate observed during an exercise performed at 60 and 75% of peak VO 2 , highlighting the absence of a lactate steady state at the same presumed level of EI. 28 Moreover, a high inter-subject variability has been observed in highly trained cyclists for RER when cycling at 79% of peak VO 2 . 29 In our population, for the definition of EI based on the percentage of peak HR and of peak VO 2 , we observed a similar trend: Indeed, the majority of cardiac patients reported a percentage of peak HR at VT 1 corresponding to the definition by previous recommendations of high rather than moderate intensity. Moreover, comparing the 2020 ESC guideline-based classification to the confidence interval of % peak VO 2 at VTs reported in Table 3, we observed that the range of % peak VO 2 at VT 1 (ie, 62-64%) and VT 2 (84-86%) are consistent with the moderate and high EI domains, respectively. ...
Article
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Background Although structured exercise training is strongly recommended in cardiac patients, uncertainties exist about the methods for determining exercise intensity (EI) and their correspondence with effective EI obtained by ventilatory thresholds. We aimed to determine the first (VT1) and second ventilatory threshold (VT2) in cardiac patients, sedentary subjects and athletes comparing VT1 and VT2 with EI defined by recommendations. Methods We prospectively enrolled 350 subjects (mean age: 50.7±12.9 years; 167 cardiac patients, 150 healthy sedentary subjects, 33 competitive endurance athletes). Each subject underwent ECG, echocardiography, and cardiopulmonary exercise testing. The percentages of peak VO2, peak heart rate (HR), and HR reserve were obtained at VT1 and VT2 and compared with the EI definition proposed by the recommendations. Results VO2 at VT1 corresponded to high rather than moderate EI in 67.1% and 79.6% of cardiac patients, applying the definition of moderate exercise by the previous recommendations and the 2020 guidelines, respectively. Most cardiac patients had VO2 values at VT2 corresponding to very-high rather than high EI (59.9% and 50.3%, by previous recommendations and 2020 guidelines, respectively). A better correspondence between ventilatory thresholds and recommended EI domains was observed in healthy subjects and athletes (90% and 93.9%, respectively). Conclusions EI definition based on percentages of peak HR and peak VO2 may misclassify the effective EI and the discrepancy between the individually determined and the recommended EI is particularly relevant in cardiac patients. A ventilatory threshold-based rather than a range-based approach is advisable to define an appropriate level of EI.
... [15][16][17][18] However, the interindividual variability in performance that occurs during exercise prescribed in this manner is large. [19][20][21][22][23] The use of RPE in production mode may provide exercise practitioners with a useful tool to consistently prescribe exercise intensity. However, with limited research exploring the impact of duration on the reliability of perceptually regulated exercise, 24,25 and no knowledge of the impact of changes in both duration and intensity on reliability, this interaction is unknown. ...
Article
Purpose: Rating of perceived exertion (RPE) as a training-intensity prescription has been extensively used by athletes and coaches. However, individual variability in the physiological response to exercise prescribed using RPE has not been investigated. Methods: Twenty well-trained competitive cyclists (male = 18, female = 2, maximum oxygen consumption =55.07 [11.06] mL·kg-1·min-1) completed 3 exercise trials each consisting of 9 randomized self-paced exercise bouts of either 1, 4, or 8 minutes at RPEs of 9, 13, and 17. Within-athlete variability (WAV) and between-athletes variability (BAV) in power and physiological responses were calculated using the coefficient of variation. Total variability was calculated as the ratio of WAV to BAV. Results: Increased RPEs were associated with higher power, heart rate, work, volume of expired oxygen (VO2), volume of expired carbon dioxide (VCO2), minute ventilation (VE), deoxyhemoglobin (ΔHHb) (P < .001), and lower tissue saturation index (ΔTSI%) and ΔO2Hb (oxyhaemoglobin; P < .001). At an RPE of 9, shorter durations resulted in lower VO2 (P < .05) and decreased ΔTSI%, and the ΔHHb increased as the duration increased (P < .05). At an RPE of 13, shorter durations resulted in lower VO2, VE, and percentage of maximum oxygen consumption (P < .001), as well as higher power, heart rate, ΔHHb (P < .001), and ΔTSI% (P < .05). At an RPE of 17, power (P < .001) and ΔTSI% (P < .05) increased as duration decreased. As intensity and duration increased, WAV and BAV in power, work, heart rate, VO2, VCO2, and VE decreased, and WAV and BAV in near-infrared spectroscopy increased. Conclusions: Self-paced intensity prescriptions of high effort and long duration result in the greatest consistency on both a within- and between-athletes basis.
... Combined with increased capillarisation , these adaptations are likely more important for endurance performance than ̇O 2max (Coyle et al., 1988;Henriksson, 1977), but despite a long-standing debate ( characterised by a substantially lower maximal mitochondrial respiratory capacity (OXPHOS; measured in permeabilised muscle fibres ex vivo) than its maximal O2 delivery (Boushel et al., 2011), ET has proven to enhance O2 extraction . ...
Thesis
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This thesis includes four research papers, based on four separate studies aiming to elucidate the importance of O2 extraction and blood volume (BV) for maximal O2 uptake (VO2max). In study I, twelve untrained subjects (VO2max: 44 ml · kg-1 · min-1) completed ten weeks of supervised endurance training (three sessions per week). VO2max and maximal cardiac output (Qmax) were measured during upright and supine cycling before and after training, as well as immediately after the training-induced gain in BV was reversed by blood withdrawal. The supine position increases venous return to the heart and may thus counteract potential adverse effects of blood withdrawal. The BV increased by 4% (~2 dl) with training. After reversing BV to the pre-training level, VO2max and Qmax remained 11% and 9% higher than before training, respectively, regardless of exercise position. By using the Fick principle (VO2 = Q × a-v ̅O2diff), it was calculated that 30% and 70% of the increase in VO2max was attributed to increased O2 content difference between arterial and mixed venous blood (a-v ̅O2diff) and increased Qmax, respectively. These improvements coincided with increased protein content of mitochondrial enzymes, a small increase in the capillary-to-fibre ratio (m. vastus lateralis) and an increased left ventricular mass (echocardiography). Thus, VO2max may increase with endurance training independent of BV expansion, caused by combined central and peripheral adaptations. In study II, thirteen subjects (VO2max: 63 ml · kg-1 · min-1) performed maximal exercise on a cycle ergometer in three experimental conditions: with normal BV and immediately after acute BV reductions of 150 ml and 450 ml, representing 2.5% and 7.6% of the total BV (6.0 l), respectively. After the 150 ml reduction, VO2max was preserved compared with the control test (non-significant reduction of 1%), likely caused by a rapid plasma volume (PV) restoration (calculated from changes in haematocrit and haemoglobin concentration). After the 450 ml BV reduction, VO2max was reduced by 7% despite partial PV restoration, increased maximal heart rate and increased leg O2 extraction as indicated by near-infrared spectroscopy. The reduction in VO2max was 2.5-fold larger after withdrawing 450 compared with 150 ml blood after normalising to the BV removed. Therefore, the body may cope with small but not moderate blood loss to preserve VO2max. These data may enhance our understanding regarding the impact of, e.g., acute BV manipulations, PV reduction following dehydration induced by prolonged exercise or hyperthermia, or daily oscillations of PV. In study III, the muscle oxidative capacity in one leg was increased by six weeks of one-legged endurance training (3-4 sessions per week) in nine subjects (VO2max: 56 ml · kg-1 · min-1). The impact on leg O2 extraction fraction (arterial and femoral venous catheters) vs the untrained control leg was investigated during dynamic two-legged knee extension exercise with both legs performing the same power output. This exercise model involves a small muscle mass, does not tax Qmax and is thus not perfusion limited. Therefore, the muscle oxidative capacity may potentially be the principal limiting factor for O2 extraction and VO2 before training. At low to moderate exercise intensities, O2 extraction fraction was similar in both legs. At higher exercise intensities, which are associated with greater mitochondrial activation and lower time for haemoglobin-O2 off-loading, the O2 extraction fraction was increased in the trained leg. The between-leg difference in O2 extraction correlated with the between-leg difference in mitochondrial protein content (m. vastus lateralis). Therefore, our data suggest that endurance training improves O2 extraction in exercise models where the mitochondria do not possess an apparent excess oxidative capacity over O2 delivery, particularly when the exercise intensity is close to maximal. In study IV, the relationships between pulmonary VO2max and systemic and leg O2 extraction fractions were investigated by statistically analysing data from 43 previously published catheterisation studies, comprising 377 subjects. It was observed that a-v ̅O2diff (mostly calculated by the Fick principle, and Qmax measured by the indicator-dilution method) increased curvilinearly and reached its maximum at ~4.5 l · min-1 in VO2max (moderately trained subjects), and was, if anything, slightly lower in those subjects with the highest VO2max (> 5 l · min-1). However, after accounting for the hypoxemia-induced lowering of arterial O2 content (CaO2) with increasing VO2max, the calculated systemic O2 extraction fraction (a-v ̅O2diff / CaO2) increased with VO2max up to ~4.5-5.0 l · min-1 and approached a plateau at ~90%. This pattern was strengthened by the direct measurements using arterial and femoral venous catheters, with leg O2 extraction fraction increasing progressively with VO2max until reaching ~90-95%. These analyses emphasise that a-v ̅O2diff and systemic O2 extraction fraction cannot be used interchangeably, and that the systemic and peripheral O2 extraction fractions improves with increasing VO2max and training status. By using the theoretical model of Piiper and Scheid, it appeared that the limiting factors to VO2max change with increasing VO2max: untrained, but healthy individuals display mixed perfusion-diffusion limitations, and this diffusion limitation reduces as VO2max increase.
... We have quantified that the aerobic system is activated to 49, 56, and 72% of maximum when taking 45-, 30-, and 15 s rest. During continuous exercise, blood lactate concentration is a reasonable indicator of glycogenolysis (Coyle et al. 1988). However, during interval exercise, the rest periods will allow time for intramuscular lactate and hydrogen ion to be lowered and move into the blood. ...
Article
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PurposeInterval exercise allows very high-power outputs to be maintained, a key for stimulating training adaptations. The main purpose of this study was to develop a sprint interval protocol that stimulated both anaerobic and aerobic systems while maximizing power output and minimizing fatigue. The secondary goal was to investigate the influence of inter-sprint recovery duration.Methods Sixteen (8 females) participants (age: 23.5 ± 3.4 years, peak oxygen consumption (VO2peak): 45.6 ± 9.2 ml kg−1 min−1) took part in this study. The exercise protocol involved 30 bouts of 4 s maximal cycling sprints using an ‘Inertial Load Ergometer’. Recovery durations between sprints of 15, 30 and 45 s were studied in three trials.ResultsPeak power output (PPO) was maintained while taking 45 and 30 s of recovery, although it was 9% higher (p < 0.05) during 45 vs. 30 s. PPO with 15 s recovery declined 18% (p < 0.05) and then stabilized as did oxygen consumption (72±2% VO2peak) at a level that might reflect the peak rate of ATP-PC resynthesis from oxidative metabolism. The 15-, 30-, and 45 s trials elicited 72, 56, and 49% VO2peak and 86, 80, and 75% of maximal heart rate (all p<0.001). Perceived exertion increased with shorter recovery periods but remained at 12.6–14.7 and never became ‘very hard’.Conclusion The present study describes the use of an inertial-load ergometer to accommodate repeated 4 s maximal cycling sprints that elicit 72% VO2peak when the recovery period is 15 s. However, a recovery duration of 15 s was insufficient for the maintenance of power generation.Trial registration number and dateNCT04448925, 26 Jun 2020; retrospectively registered to clinicaltrials.gov.
... Some of the more notable measures that have been examined are VO 2max , time-toexhaustion (TTE) tests, and time-trial (TT) tests. VO 2max is highly correlated with race performance [17] but has limitations because it does not account for additional physiological differences [18,19]. The reliability of TTE tests has been shown to be lower than TT tests [20]. ...
Article
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Background Interval training has become an essential component of endurance training programs because it can facilitate a substantial improvement in endurance sport performance. Two forms of interval training that are commonly used to improve endurance sport performance are high-intensity interval training (HIIT) and sprint interval training (SIT). Despite extensive research, there is no consensus concerning the optimal method to manipulate the interval training programming variables to maximize endurance performance for differing individuals.Objective The objective of this manuscript was to perform a systematic review and meta-analysis of interval training studies to determine the influence that individual characteristics and training variables have on time-trial (TT) performance.Data SourcesSPORTDiscus and Medline with Full Text were explored to conduct a systematic literature search.Study SelectionThe following criteria were used to select studies appropriate for the review: 1. the studies were prospective in nature; 2. included individuals between the ages of 18 and 65 years; 3. included an interval training (HIIT or SIT) program at least 2 weeks in duration; 4. included a TT test that required participants to complete a set distance; 5. and programmed HIIT by power or velocity.ResultsTwenty-nine studies met the inclusion criteria for the quantitative analysis with a total of 67 separate groups. The participants included males (n = 400) and females (n = 91) with a mean group age of 25 (range 19–45) years and mean \(V{\text{O}}_{{2{\text{max}}}}\) of 52 (range 32–70) mL·kg−1·min−1. The training status of the participants comprised of inactive (n = 75), active (n = 146) and trained (n = 258) individuals. Training status played a significant role in improvements in TT performance with trained individuals only seeing improvements of approximately 2% whereas individuals of lower training status demonstrated improvements as high as 6%. The change in TT performance with HIIT depended on the duration but not the intensity of the interval work-bout. There was a dose–response relationship with the number of HIIT sessions, training weeks and total work with changes in TT performance. However, the dose–response was not present with SIT.Conclusion Optimization of interval training programs to produce TT performance improvements should be done according to training status. Our analysis suggests that increasing interval training dose beyond minimal requirements may not augment the training response. In addition, optimal dosing differs between high intensity and sprint interval programs.
... A change in body position resulting from alterations to saddle position will effect knee angle (Bini, Hume, & Croft, 2014) and pedalling cadence (Heil et al., 1997) as well as aerodynamic drag. In the laboratory, where resistive forces are controlled or minimised, these factors have been successfully used to predict simulated time trial performance (Coyle et al., 1985). When cycling outside on level terrain the total resistance impeding the forward motion of a bicycletriathlete system is determined by aerodynamic resistance. ...
... Also, enhanced power rotation through more muscle mass increases the VO 2 at the lactate threshold due to increased mitochondrial sharing for a given metabolic rate. 12 The VO 2 at lactate threshold has been shown to be an important indicator for expressing an individual's metabolic capacities for endurance exercise 12,29 and potentially an important factor for TT performance. However, in the current study, the theoretical benefit of an enhanced rotation in motor unit recruitment is not supported by a decrease in muscle fatigue, represented by the change in EMGmf over the TTs. ...
Article
Background: During self-paced (SP) time trials (TTs), cyclists show unconscious nonrandom variations in power output of up to 10% above and below average. It is unknown what the effects of variations in power output of this magnitude are on physiological, neuromuscular, and perceptual variables. Purpose: To describe physiological, neuromuscular, and perceptual responses of 10-km TTs with an imposed even-paced (EP) and variable-paced (VP) workload. Methods: Healthy male, trained, task-habituated cyclists (N = 9) completed three 10-km TTs. First, an SP TT was completed, the mean workload from which was used as the mean workload of the EP and VP TTs. The EP was performed with an imposed even workload, while VP was performed with imposed variations in workload of ±10% of the mean. In EP and VP, cardiorespiratory, neuromuscular, and perceptual variables were measured. Results: Mean rating of perceived exertion was significantly lower in VP (6.13 [1.16]) compared with EP (6.75 [1.24]), P = .014. No mean differences were found for cardiorespiratory and almost all neuromuscular variables. However, differences were found at individual kilometers corresponding to power-output differences between pacing strategies. Conclusion: Variations in power output during TTs of ±10%, simulating natural variations in power output that are present during SP TTs, evoke minor changes in cardiorespiratory and neuromuscular responses and mostly affect the perceptual response. Rating of perceived exertion is lower when simulating natural variations in power output, compared with EP cycling. The imposed variations in workload seem to provide a psychological rather than a physiological or neuromuscular advantage.
... La fraction d'utilisation de la consommation maximale d'oxygène augmentation de la densité mitochondriale et du nombre de fibres musculaires oxydatives impliquées dans l'activité, ce qui réduit la production d'acide lactique à une intensité sous-maximale, qui au pH cellulaire est hydrolysé en lactate et proton (H + ) (Bassett and Howley, 2000;Coyle et al., 2017). Lors d'un effort en endurance, l'accumulation d'ions H + doit être limitée pour réduire l'acidose métabolique et maintenir l'intensité de l'effort requise (Bassett and Howley, 2000;Wasserman, 1986). ...
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This thesis project aimed at improving scientific knowledge in the field of short distance trail running, a “booming” activity. Situated between "traditional" road races and ultra-trail races, limited research has focused on the analysis of short distance trail running . The first objective was to characterize the physiological determinants of performance during short distance trail running races in a population of highly trained runners, using an experimental setting between laboratory protocols and an official event. The identification of muscular endurance as critical factor in the determination of performance leads to the second objective of the current thesis, based on the acute and delayed effects of wearing compression garments on neuromuscular function and energetic parameters during a short distance trail run or during intense eccentric exercise (i.e. prolonged downhill run). Wearing compression garments contributes to the attenuation of soft tissue vibrations which can reduce, at least in part, the deficit of voluntary activation level measured immediately after downhill running and improve the neuromuscular function during the recovery phase. Our results suggest that the use of garments with high compression intensity during exercise could exert a “mechanical protective effect”, which could therefore constitute an external strategy to tolerate a high training load or optimize the recovery process in multi-stage races.
... Power, FTP) como la mayor potencia que un deportista puede mantener en un estado de casi estado estable durante aproximadamente 60 minutos. Coyle et al. (1988) mostraron que la salida de potencia o el ritmo más alto que un atleta puede mantener en el transcurso de una tarea de ejercicio de una hora de duración está altamente correlacionada con el LT. ...
Research
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El control de la carga externa utilizando un medidor de potencia se está extendiendo recientemente entre los atletas y triatletas. Se plantea como objetivo determinar si el medidor de potencia Stryd es válido para el control del entrenamiento y para su posterior análisis de puntuación de carga. Se desarrolla un estudio de campo durante un periodo de 12 semanas (tiempo en el que el programa Powercenter de Stryd genera la curva de potencia crítica) donde se analizan los datos de los entrenamientos de carrera de un triatleta amateur. Para ello, se utiliza los softwares Trainingpeaks y Powercenter para comparar las métricas de cuantificación hrTSS, rTSS, TSS y RSS. También se realiza un análisis de la evolución de los parámetros relacionados con la técnica de carrera. Los resultados de análisis invitan a utilizar la curva de potencia crítica generada de la recogida de datos con el medidor Stryd como predictor del estado de forma del deportista, así como a utilizar dicho medidor para controlar variables relacionadas con la técnica de carrera.
... In track-andfield, international caliber sprinters can be found at the fast side of the continuum, demonstrating a low percentage of slow-twitch fibers (21-28% slow-twitch fibers in the gastrocnemius), middle-distance runners occupy the center, showing a mix between both fibers (41-73% slowtwitch fibers in the gastrocnemius), while distance runners can be located at the slow side of the continuum (63-74% slow-twitch fibers in the gastrocnemius) (13). Literature on the muscle typology of cyclists is less conclusive, as -well-trained‖ road cyclists span the full range of 17 to 85% slow-twitch fibers in the vastus lateralis (3,7,(14)(15)(16)(17). However, it is still unclear if part of this range can be explained by differences in athlete level and specialization (single vs multistage oriented cyclists). ...
Article
Purpose: Classic track-and-field studies demonstrated that elite endurance athletes exhibit a slow muscle typology, whereas elite sprint athletes have a predominant fast muscle typology. In elite cycling, conclusive data on muscle typology are scarce, which may be due to the invasive nature of muscle biopsies. The noninvasive estimation of muscle typology through the measurement of muscle carnosine enabled to explore the muscle typology of 80 world-class cyclists of different disciplines. Methods: The muscle carnosine content of 80 cyclists (4 bicycle motor cross racing [BMX], 33 track, 8 cyclo-cross, 24 road, and 11 mountain bike) was measured in the soleus and gastrocnemius by proton magnetic resonance spectroscopy and expressed as a z-score relative to a reference population. Track cyclists were divided into track sprint and endurance cyclists based on their Union Cycliste Internationale (UCI) ranking. Moreover, road cyclists were further characterized based on the percentage of UCI points earned during either single and multistage races. Results: BMX cyclists (carnosine aggregate z-score of 1.33) are characterized by a faster muscle typology than track, cyclo-cross, road, and mountain bike cyclists (carnosine aggregate z-score of -0.08, -0.76, -0.96, and -1.02, respectively; P < 0.05). Track cyclists also possess a faster muscle typology compared with mountain bikers (P = 0.033) and road cyclists (P = 0.005). Moreover, track sprinters show a significant faster muscle typology (carnosine aggregate z-score of 0.87) compared with track endurance cyclists (carnosine aggregate z-score of -0.44) (P < 0.001). In road cyclists, the higher the carnosine aggregate z-score, the higher the percentage of UCI points gained during single-stage races (r = 0.517, P = 0.010). Conclusions: Prominent differences in the noninvasively determined muscle typology exist between elite cyclists of various disciplines, which opens opportunities for application in talent orientation and transfer.
... This may also explain the lack of differences in gastrocnemius and hamstring activation from pre-to post-training. Furthermore, trained cyclists can generate higher force at a lower oxygen cost compared to novice cyclists (Coyle, Coggan, Hopper, & Walters, 1988). Due to our subjects status as well-trained runners, with little experience of cycling, the athletes demonstrated an adaptation to cycling through an increase in quadriceps activation. ...
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Background: High-intensity interval training (HIIT) has grown in popularity, with studies demonstrating improvements in aerobic and anaerobic performances within Sedentary and Recreationally active adults. Little research has been comprised on collegiate, middle-distance runners (800m/1500m). Objective: This research study aimed to investigate the impact of four-weeks HIIT cycling training on collegiate 800/1500m runners performance, and determine whether HIIT can be used as an alternative training method for student athletes. Methods: Twelve middle-distance runners were recruited, with six athletes completing the intervention. Athletes completed pre-testing, which included a 1500m time trial, a GXT, stride length and frequency measurements, and MVIC, using Biopac electromyography (EMG). After pre-testing, athletes completed four weeks of HIIT twice per week. The HIIT consisted of four 20-second bouts with 4 minutes recovery. Following the completion of the training intervention, post-testing was performed for all measures. A paired t-test was used to determine differences between pre- and post-performance tests. An ANOVA was used to determine changes in heart rate and RPE during the GXT. Results: Significant changes were demonstrated between the pre- and post-muscle activation tests of the quadriceps (p=0.05). Significant changes were seen with both HR (p<0.05) and RPE (p<0.05) throughout the GXT. No other significant differences were demonstrated between pre- and post-performance tests, concluding four-weeks HIIT does not alter 800/1500m performance. Conclusion: From the results of this study, HIIT could be used as an alternate method for training for 800/1500m runners. Further reasearch should be conducted toto further understand the impacts of HIIT on middle distance athletes.
... One hallmark adaptation to endurance exercise training is increased oxygen-transport capacity, as measured by VO 2 max 78 , thus leading to greater fatigue resistance and enhanced exercise performance 79 . The other is enhanced skeletal muscle mitochondrial density 80 , a major factor contributing to decreased carbohydrate utilization and oxidation and lactate production 81,82 , increased fat oxidation and enhanced endurance exercise performance 83 . The capacity for muscle carbohydrate oxidation also increases, thereby enabling maintenance of a higher power output during exercise and enhanced performance 84 . ...
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An amendment to this paper has been published and can be accessed via a link at the top of the paper.
... Cioè, perché a un certo punto mantenere la velocità desiderata non sembra più possibile? Prima di tutto precisiamo che l'escursionismo è un'attività motoria di resistenza, dal momento che caratteristica importante della resistenza è la tolleranza all'esercizio [exercise tolerance], cioè la capacità dell'organismo di sostenere un esercizio muscolare generalizzato in condizioni aerobiche, per un tempo protratto (Coyle et al., 1988, Marcora e Staiano, 2010. Ed in effetti camminare è un esercizio fisico aerobico e durante le escursioni lo facciamo per ore, a seconda del livello di difficoltà. ...
Article
The factors explaining variance in thermoneutral maximal oxygen uptake (V˙O2max) adaptation to heat acclimation (HA) were evaluated, with consideration of HA programme parameters, biophysical variables and thermo-physiological responses. Seventy-one participants consented to perform iso-intensity training (range: 45%-55% V˙O2max) in the heat (range: 30°C-38°C; 20%-60% relative humidity) on consecutive days (range: 5-days-14-days) for between 50-min and-90 min. The participants were evaluated for their thermoneutral V˙O2max change pre-to-post HA. Participants' whole-body sweat rate, heart rate, core temperature, perceived exertion and thermal sensation and plasma volume were measured, and changes in these responses across the programme determined. Partial least squares regression was used to explain variance in the change in V˙O2max across the programme using 24 variables. Sixty-three percent of the participants increased V˙O2max more than the test error, with a mean ± SD improvement of 2.6 ± 7.9%. A two-component model minimised the root mean squared error and explained the greatest variance (R2; 65%) in V˙O2max change. Eight variables positively contributed (P < 0.05) to the model: exercise intensity (%V˙O2max), ambient temperature, HA training days, total exposure time, baseline body mass, thermal sensation, whole-body mass losses and the number of days between the final day of HA and the post-testing day. Within the ranges evaluated, iso-intensity HA improved V˙O2max 63% of the time, with intensity- and volume-based parameters, alongside sufficient delays in post-testing being important considerations for V˙O2max maximisation. Monitoring of thermal sensation and body mass losses during the programme offers an accessible way to gauge the degree of potential adaptation.
Article
Purpose: Investigate whether a cloth facemask could affect physiological and perceptual responses to exercise at distinct exercise intensities in untrained individuals. Methods: Healthy participants (n = 35; 17 men, age 30 [4] y, and 18 women, age 28 [5] y) underwent a progressive square wave test at 4 intensities: (1) 80% of ventilatory anaerobic threshold; (2) ventilatory anaerobic threshold; (3) respiratory compensation point; and (4) exercise peak (Peak) to exhaustion, 5-minute stages, with or without a triple-layered cloth facemask (Mask or No-Mask). Several physiological and perceptual measures were analyzed. Results: Mask reduced inspiratory capacity at all exercise intensities (P < .0001). Mask reduced respiratory frequency (P = .001) at Peak (-8.3 breaths·min-1; 95% confidence interval [CI], -5.8 to -10.8), respiratory compensation point (-6.9 breaths·min-1; 95% CI, -4.6 to -9.2), and ventilatory anaerobic threshold (-6.5 breaths·min-1; 95% CI, -4.1 to -8.8), but not at Baseline or 80% of ventilatory anaerobic threshold. Mask reduced tidal volume (P < .0001) only at respiratory compensation point (-0.5 L; 95% CI, -0.3 to -0.6) and Peak (-0.8 L; 95% CI, -0.6 to -0.9). Shallow breathing index was increased with Mask only at Peak (11.3; 95% CI, 7.5 to 15.1). Mask did not change HR, lactate, ratings of perceived exertion, blood pressure, or oxygen saturation. Conclusions: A cloth facemask reduced time to exhaustion but had no major impact on cardiorespiratory parameters and had a slight but clinically meaningless impact on respiratory variables at higher intensities. Moderate to heavy activity is safe and tolerable for healthy individuals while wearing a cloth facemask. Clinicaltrials: gov: NCT04887714.
Article
Introduction: Obesity effects on kidney function. Urinary disorders after exercise are also common, and probably due to transient hemodynamic problems in the glomerular and tubular renal function. The purpose of this research is to investigate the relationship of BMI with proteinuria and hematuria after one session of intense continuous and interval exercise in girls. Methods: In this quasi-experimental research, 45 hostelry high school girl students with a mean age of 15.18 ± 0.39 years were randomly selected and in three groups of 15, they ran 1600 meters in a continuous and interval manner. Urine test collected before, one and 24 hours after activity. The results were analyzed by SPSS version 16 software and one way ANOVA and Pearson correlation coefficient. Results: Increased proteinuria was significant one hour (P = 0.002) and 24 hours after activity (P = 0.001) in the continuous group. In the continuous group, the relationship between fat percentage (P=0.017) and body mass index (P=0.001) with protein excretion 24 hours after activity was positive and significant. One hour after activity, protein excretion with fat percentage and Body mass index (BMI) had no significant relationship. Hematuria was also not significant after activity. Conclusion: Body mass index (BMI) and fat percentage were effective on protein excretion after one session of intense physical activity and had no significant effect on hematuria. Therefore, overweight people were advised to participate in interval exercise to lose weight.
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Exercise stress testing (EST) is indicated for diagnostic and prognostic purposes in the general population. In athletes, stress tests can also be useful to inform the risk of high-intensity training and competition, to assess athletic conditioning, and to refine training regimens. Many specific indications for EST are unique to athletes. Treadmill and cycle ergometer protocols each have their strengths and disadvantages; extensive protocol customization may be necessary to answer the clinical question at hand. A comprehensive understanding of the available tools for exercise testing, their strengths, and their limitations is crucial to providing cardiovascular care to athletic individuals.
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OBJECTIVE. The aim of this study was to investigate the relationship between the aerobic capacity (VO2max) and academic performance and the different components of the cognitive functions of the brain, including spatial memory, attention, problem solving, flexibility, mathematics in medicine students. METHODS. Aerobic capacity measurement was performed by cardiopulmonary exercise test and VO2max measurement in Exercise Physiology Laboratory at Göztepe EAH Merdivenköy Polyclinic in İstanbul Medeniyet University. The measurement of body composition was performed in the Student Physiology Laboratory of the Medical Faculty of Istanbul Medeniyet University. To evaluate cognitive performance, In the Student Computer Laboratory, with Lumosity programme 6 categories of cognitive tests related to speed, memory, attention, flexibility, problem solving and mathematics were applied and evaluated. To assess the academic performance, The final exam grade point averages and weighted grade point averages and LYS entry points of the students who will participate in the study were taken from the student affairs department. The relationships between brain cognitive functions and academic performance and aerobic capacity were evaluated by correlation and regression analysis. RESULTS. When the relationship between aerobic capacity and cognitive performance was examined; Flexibility (r = 0,332 p = 0,007), Problem Solving (r = 0,248 p = 0,047) and Attention (r = 0,248 p = 0,047) from the cognitive performance test categories with aerobic capacity (VO2max) a positive linear relationship was found between them. There was no significant relationship between aerobic capacity and school success. vii Abstract CONCLUSION. As a result of this study, it was found that there is a relationship between aerobic capacity and some of cognitive performance tests in medical school students. However is was not found any relationship between aerobic capacity and school success. This situation may be caused by other factors affecting the success of the school. Keywords: VO2max, aerobic capacity, cognitive performance, academic performance
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Guiding cyclists in their return from illness and injury can be managed in many ways. Understanding how cyclists use power-derived training metrics can give care providers a common language to aid in this return. A general understanding of these metrics may be used to monitor cyclists for signs of nonfunctional overreaching or overtraining. Understanding aspects of training and detraining, particularly hematological, is helpful in communicating fitness expectations. Three populations of cyclists are discussed in terms of their expected knowledge of these metrics, typical training volume and intensity, and relationship with a coach or coaches.
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Smith, NDW, Scott, BR, Girard, O, and Peiffer, JJ. Aerobic training with blood flow restriction for endurance athletes: potential benefits and considerations of implementation. J Strength Cond Res XX(X): 000-000, 2021-Low-intensity aerobic training with blood flow restriction (BFR) can improve maximal oxygen uptake, delay the onset of blood lactate accumulation, and may provide marginal benefits to economy of motion in untrained individuals. Such a training modality could also improve these physiological attributes in well-trained athletes. Indeed, aerobic BFR training could be beneficial for those recovering from injury, those who have limited time for training a specific physiological capacity, or as an adjunct training stimulus to provide variation in a program. However, similarly to endurance training without BFR, using aerobic BFR training to elicit physiological adaptations in endurance athletes will require additional considerations compared with nonendurance athletes. The objective of this narrative review is to discuss the acute and chronic aspects of aerobic BFR exercise for well-trained endurance athletes and highlight considerations for its effective implementation. This review first highlights key physiological capacities of endurance performance. The acute and chronic responses to aerobic BFR exercise and their impact on performance are then discussed. Finally, considerations for prescribing and monitoring aerobic BFR exercise in trained endurance populations are addressed to challenge current views on how BFR exercise is implemented.
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Since ancient times, the health benefits of regular physical activity/exercise have been recognised and the classic studies of Morris and Paffenbarger provided the epidemiological evidence in support of such an association. Cardiorespiratory fitness, often measured by maximal oxygen uptake, and habitual physical activity levels are inversely related to mortality. Thus, studies exploring the biological bases of the health benefits of exercise have largely focused on the cardiovascular system and skeletal muscle (mass and metabolism), although there is increasing evidence that multiple tissues and organ systems are influenced by regular exercise. Communication between contracting skeletal muscle and multiple organs has been implicated in exercise benefits, as indeed has other inter-organ "cross-talk". The application of molecular biology techniques and 'omics' approaches to questions in exercise biology has opened new lines of investigation to better understand the beneficial effects of exercise and, in so doing, inform the optimisation of exercise regimens and the identification of novel therapeutic strategies to enhance health and well-being.
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My Undergraduate Dissertation Project - This was a case study project (N=1) Explorative piece of working, looking to understand the physiological demands of an ultra endurance mountain bike event at the 2016 WEMBO Race
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The shining bicycle, its spokes blurred by speed, conveys a memory of childhood and freedom. You pump the pedals and the ground under you scrolls by, the wind tastes fresh in your mouth, and you escape … there is efficiency and grace in being not only the bicycle’s passenger, but its engine.
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It is believed that neutrophils extracellular traps (NETs) formation is responsible for the increase in cf DNA after exercise. Since T1DM is accompanied by enhanced NETs generation, we compared exercise-induced increase in cf DNA in 14 men with T1DM and 11 healthy controls and analyzed its association with exercise load. Subjects performed a treadmill run to exhaustion at speed corresponding to 70% of their personal VO2max. Blood was collected before and just after exercise for determination of plasma cf nuclear and mitochondrial DNA (cf n-DNA, cf mt-DNA) by real-time PCR, blood cell count and metabolic markers. Exercise resulted in the increase in median cf n-DNA from 3.9 ng/mL to 21.0 ng/mL in T1DM group and from 3.3 ng/mL to 28.9 ng/mL in controls. Median exercise-induced increment (∆) in cf n-DNA did not differ significantly in both groups (17.8 ng/mL vs. 22.1 ng/mL, p = 0.23), but this variable correlated with run distance (r = 0.66), Δ neutrophils (r = 0.86), Δ creatinine (r = 0.65) and Δ creatine kinase (r = 0.77) only in controls. Pre- and post-exercise cf mt-DNA were not significantly different within and between groups. These suggest low usefulness of Δ cf n-DNA as a marker of exercise intensity in T1DM men.
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New findings: Blood flow restricted (BFR) exercise represents an approach to potentially augment the adaptive response to training and improve performance in endurance trained individuals. When combined with low-load resistance exercise, low- and moderate-intensity endurance exercise, and sprint interval exercise, BFR can provide an augmented acute stimulus for angiogenesis and mitochondrial biogenesis. These augmented acute responses can translate to enhanced capillary supply and mitochondrial function, and subsequent endurance-type performance, although this may depend on the nature of the exercise stimulus. There is a requirement to clarify whether BFR-training interventions can be utilised by high-performance endurance athletes within their structured training programme. Abstract: A key objective of an endurance athlete's training programme is to optimise the underlying physiological determinants of performance. Training-induced adaptations are governed by physiological and metabolic stressors which initiate transcriptional and translational signalling cascades to increase the abundance and/or function of proteins to improve physiological function. One important consideration is that training adaptations are reduced as training status increases, which is reflected at the molecular level as a blunting of the acute signalling response to exercise. This review examines blood-flow-restricted (BFR) exercise as a strategy for augmenting exercise-induced stressors and subsequent molecular signalling responses to enhance the physiological characteristics of the endurance athlete. Focus is placed on the processes of capillary growth and mitochondrial biogenesis. Recent evidence supports that BFR exercise presents an intensified training stimulus beyond that of performing the same exercise alone. We suggest this has the potential to induce enhanced physiological adaptations, including increases in capillary supply and mitochondrial function, which can contribute to improving endurance-exercise performance. There is, however, a lack of consensus as to the potency of BFR-training which is invariably due to the different modes, intensities, and durations of exercise and BFR methods. Further studies are needed to confirm its potential in the endurance-trained athlete. This article is protected by copyright. All rights reserved.
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Background: Multiple sclerosis (MS) is an autoimmune disease that impacts the central nervous system. MS generally results in decreased mobility and work capacity. Our objective was to determine exercise testing responses on both a treadmill and cycle ergometer among individuals with MS who were able to ambulate freely. Methods: Twenty-six individuals with MS participated in a cross-sectional study (44 ± 11 years; body mass index 26.8 ± 6.2 kg·m−2; expanded disability scale score 3.1 ± 0.9), with 24 individuals with complete test data for both treadmill and cycle ergometry tests. Peak aerobic capacity (VO2peak) for both treadmill and cycle ergometry tests were measured with indirect calorimetry. Results: Participants safely completed both treadmill and cycle ergometry tests, and treadmill testing yielded higher values (26.7 ± 6.4 mL·kg−1·min−1) compared with cycle ergometry (23.7 ± 5.7 mL·kg−1·min−1), with values ~12% greater for treadmill. When comparing tests to their respected predicted values within modality, treadmill tests were 8% lower and cycle ergometry tests were 10% lower than predicted. Conclusions: While peak aerobic capacity was very low for this population, treadmill tests were still higher than cycle ergometry data, with this difference between modes being similar to that observed in healthy adult populations. Additional research is required to determine if these findings are impacted by participation in physical activity or regular exercise.
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This study was undertaken to determine the response of $\dot V$ O2 max and of running performance (805 and 3218 m) to the onset of training in untrained individuals and to an increase in the volume and intensity of training in well trained individuals. In series A, $\dot V$ O2 max and performances of 12 previously untrained individuals were determined before and after 4 and 8 weeks of training. In series B, performances, $\dot V$ O2 max and $\dot V$ O2 submax of 15 previously well trained runners were determined before and after 4 and 8 weeks of controlled training. In series A, $\dot V$ O2 max increased during the first 4 weeks of training but failed to increase further even in the presence of an increased training load (80 total km for the first 4 weeks, 130 total km for the second 4 weeks). Running performances improved throughout the training period. In series B, neither $\dot V$ O2 max nor $\dot V$ O2 submax changed but running performance improved throughout the experimental period. The results indicated that not all of the improvement in running performance subsequent to training is attributable to changes in $\dot V$ O2 max. Further the results indicate that changes in running economy are not a likely explanation for performance improvement among previously well trained runners. It is suggested that physiological adaptations not integrated in the test of $\dot V$ O2 max, or improvement in pacing contribute to training induced improvements in running performance.
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Performance in marathon running is influenced by a variety of factors, most of which are of a physiological nature. Accordingly, the marathon runner must rely to a large extent on a high aerobic capacity. But great variations in maximal oxygen uptake (VO2 max) have been observed among runners with a similar performance capacity, indicating complementary factors are of importance for performance. The oxygen cost of running or the running economy (expressed, e.g. as VO2 15 at 15 km/h) as well as the fractional utilisation of VO2 max at marathon race pace (%VO2 Ma X VO2 max-1) [where Ma = mean marathon velocity] are additional factors which are known to affect the performance capacity. Together VO2 max, VO2 15 and %VO2 Ma X VO2 max-1 can almost entirely explain the variation in marathon performance. To a similar degree, these variables have also been found to explain the variations in the 'anaerobic threshold'. This factor, which is closely related to the metabolic response to increasing exercise intensities, is the single variable that has the highest predictive power for marathon performance. But a major limiting factor to marathon performance is probably the choice of fuels for the exercising muscles, which factor is related to the %VO2 Ma X VO2 max-1. Present indications are that marathon runners, compared with normal individuals, have a higher turnover rate in fat metabolism at given high exercise intensities expressed both in absolute (m/sec) and relative (%VO2 max) terms. The selection of fat for oxidation by the muscles is important since the stores of the most efficient fuel, the carbohydrates, are limited. The large amount of endurance training done by marathon runners is probably responsible for similar metabolic adaptations, which contribute to a delayed onset of fatigue and raise the VO2 Ma X VO2max-1. There is probably an upper limit in training kilometrage above which there are no improvements in the fractional utilisation of VO2 max at the marathon race pace. The influence of training on VO2 max and, to some extent, on the running economy appears, however, to be limited by genetic factors.
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Eight well-trained middle and long distance male runners added to their regular training program a weekly 20-min treadmill run at a velocity calculated to elicit a blood lactate concentration of 4 mmol X 1-1. VO2 max, the running velocity eliciting 4 mmol X 1-1 blood lactate (VOBLA), and the activities of citrate synthase (CS), phosphofructokinase (PFK), lactate dehydrogenase (LDH) and LDH isozymes in the M. vastus lateralis were determined before and after 14 weeks of this training. Significant increases were observed in VOBLA and the relative fraction of heart-specific LDH, while the activity of PFK and the ratio of PFK/CS decreased after training. The change in VOBLA was negatively correlated to the mean rate of blood lactate accumulation during the last 15 min of the treadmill training runs, and positively correlated to the percentage of slow twitch fibers in the M. vastus lateralis. The data support the hypothesis that a steady state training intensity which approximates VOBLA will increase VOBLA, and will result in measureable local metabolic adaptations in the active skeletal muscles of well-trained runners without a significant change in maximal aerobic power. Muscle fiber type composition may be an indicator of the "trainability" of the musculature.
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A computer-based instrumentation system was used to accurately measure the six foot-pedal load components and the absolute pedal position during bicycling. The instrumentation system is the first of its kind and enables extensive and meaningful biomechanical analysis of bicycling. With test subjects riding on rollers which simulate actual bicycling, pedalling data were recorded to explore four separate hypotheses. Experiments yielded the following major conclusions: (1) Using cleated shoes retards fatigue of the quadriceps muscle group. By allowing more flexor muscle utilization during the backstroke, cleated shoes distribute the workload and alleviate the peak load demand on the quadriceps group; (2) overall pedalling efficiency increases with power level; (3) non-motive load components which apply adverse moments on the knee joint are of significant magnitude; (4) analysis of pedalling is an invaluable training aid. One test subject reduced his leg exertion at the pedal by 24 per cent.
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This study examined the relationship between the respiratory capacity of an individual's skeletal muscle and the work rate at which blood lactate accumulation begins (lactate threshold). Comparisons were also made among fiber type, VO2max, and the lactate threshold. Muscle biopsies were taken from the vastus lateralis muscle for determination of respiratory capacity and fiber type (myosin ATPase). The lactate threshold was assessed in terms of both the absolute work rate (VO2) and relative work rate (%VO2max). The capacity of muscle homogenates to oxidize pyruvate was significantly (P less than 0.01) related to the absolute (r = 0.94) and relative (r = 0.83) lactate thresholds. Significant positive correlations (P less than 0.01) were also found between the percent of slow-twitch fibers and absolute (r = 0.74) and relative (r = 0.70) lactate thresholds. The results suggest that the muscle's respiratory capacity is of primary importance in determining the work rate at which blood lactate accumulation begins. They also suggest that the proportion of slow-twitch fibers may play an important role in determining the relative lactate threshold.
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The purpose of the study was to determine the relationship between running economy and distance running performance in highly trained and experienced distance runners of comparable ability. Oxygen uptake (Vo2) during steady-state and maximal aerobic power (Vo2max) were measured during treadmill running using the open-circuit method. Distance running performance was determined in a nationally prominent 10 km race; all subjects (12 males) placed among the top 19 finishers. The subjects averaged 32.1 min on the 10 km run, 71.7 ml.kg-1.min-1 for Vo2max, and 44.7, 50.3, and 55.9 ml.kg-1.min-1 for steady-state Vo2 at three running paces (241, 268, and 295 m.min-1). The relationship between Vo2max and distance running performance was r = -0.12 (p = 0.35). The relationship between steady-state Vo2 at 241, 268 and 295 m.min-1 and 10 km time were r = 0.83, 0.82, and 0.79 (p < 0.01), respectively. Within this elite cluster of finishers, 65.4% of the variation observed in race performance time on the 10 km run could be explained by variation in running economy. It was concluded that among highly trained and experienced runners of comparable ability and similar Vo2max, running economy accounts for a large and significant amount of the variation observed in performance on a 10 km race.
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Metabolic differentiation of muscle tissue may be understood from the viewpoints of quantitative and qualitative adaptation. Quantitatively, it is the consequence of a balance of input of chemical energy and output of mechanical work in the myofibrillar apparatus. Qualitatively, it is the expression of an adjustment to the functional characteristics of the muscle, such as the quality and temporal pattern of energy expenditure (e.g. steady and continuous, steady and discontinuous or dicontinuous performance of work. The kinds of metabolic differentiation possible are based on the fact that muscle cells may draw energy from the oxidation of various fuels. The caloric values of the various fuels determine their different theoretical maximum energy-yields. The nature of the fuel also determines the type of its metabolism, especially with regard to an obligatory or nonobligatory aerobic catabolism. Energy-output in cell metabolism depends finally on the catabolic rate. Nature of the fuel, type of metabolism and catabolic rate thus represent fundamental elements in metabolic differentiation.
Article
Muscle samples from the vastus lateralis and maximal oxygen uptakes were obtained from 22 male and 7 female competitive cyclists. 19 untrained males, and 10 untrained females. Eleven of the 22 male cyclists were designated elite cyclists (Group A) on the basis of their success in national and/or international competition. The remaining 11 male cyclists (Group B) were also trained but had not achieved the same level of competitive success. Significant mean differences (P less than 0.05) between Groups A and B were found for VO2 max (67 and 57 ml/kg/min), malate dehydrogenase (MDH) and phosphorylase (PH), in biopsied muscle. No differences were evident between Groups A and B for % slow twitch (ST) and % fast twitch (FT) fibers, or in area FT or ST. Nor was there any difference in the mean activities of succinate dehydrogenase (SDH) and lactate dehydrogenase (LDH) between the groups. Significant correlations were found between VO2 max and SDH, VO2 max and MDH, and between SDH and MDH. These data also indicate that an extremely high percentage of FT or ST fibers may not be a requirement for success in competitive cycling as has been found in earlier studies on sprint or endurance running.
Article
Seven endurance-trained subjects were studied 12, 21, 56, and 84 days after cessation of training. Heart rate, ventilation, respiratory exchange ratio, and blood lactate concentration during submaximal exercise of the same absolute intensity increased (P less than 0.05) progressively during the first 56 days of detraining, after which a stabilization occurred. These changes paralleled a 40% decline (P less than 0.001) in mitochondrial enzyme activity levels and a 21% increase in total lactate dehydrogenase (LDH) activity (P less than 0.05) in trained skeletal muscle. After 84 days of detraining, the experimental subjects' muscle mitochondrial enzyme levels were still 50% above, and LDH activity was 22% below, sedentary control levels. The blood lactate threshold of the detrained subjects occurred at higher absolute and relative (i.e., 75 +/- 2% vs. 62 +/- 3% of maximal O2 uptake) exercise intensities in the subjects after 84 days of detraining than in untrained controls (P less than 0.05). Thus it appears that a portion of the adaptation to prolonged and intense endurance training that is responsible for the higher lactate threshold in the trained state persists for a long time (greater than 85 days) after training is stopped.
Article
Tissue samples were obtained from vastus lateralis and deltoid muscles of physical education students (n = 12), Greco-Roman wrestlers (n = 8), flat-water kayakers (n = 9), middle- and long-distance runners (n = 9), and olympic weight and power lifters (n = 7). Histochemical stainings for myofibrillar adenosinetriphosphatase and NADH-tetrazolium reductase were applied to assess the relative distribution of fast-twitch and slow-twitch (ST) muscle fiber types and fiber size. The %ST was not different in the vastus (mean SD 48 +/- 14) and deltoid (56 +/- 13) muscles. The %ST was higher (P less than 0.001), however, in the deltoid compared with vastus muscle of kayakers. This pattern was reversed in runners (P less than 0.001). The %ST of the vastus was higher (P less than 0.001) in runners than in any of the other groups. The %ST of the deltoid muscle was higher in kayakers than in students, runners (P less than 0.001), and lifters (P less than 0.05). The mean fiber area and the area of ST fibers were greater (P less than 0.01) in the vastus than the deltoid muscle. Our data show a difference in fiber type distribution between the trained and nontrained muscles of endurance athletes. This pattern may reflect the adaptive response to long-term endurance training.
Article
Activity levels of glycogen phosphorylase, hexokinase, triosephosphate dehydrogenase, lactate dehydrogenase, citrate synthase, 3-hydroxyacyl-CoA dehydrogenase, glycerolphosphate dehydrogenase (mitochondrial), and hexosediphosphatase have been determined in white (fast) muscles, red (slow) muscles, heart and smooth muscle of higher animals. The activities of these enzymes are taken as relative measures of metabolic capacities. Their ratios are interpreted as representing relations of different metabolic pathways or systems. In all muscles investigated comparable ratios exist for phosphorylase/triosephosphate dehydrogenase (glycogenolysis/glycolysis), glycerolphosphate dehydrogenase/triosephosphate dehydrogenase (mitochondrial glycerolphosphate oxidation/glycolysis), triosephosphate dehydrogenase/lactate dehydrogenase (glycolysis/lactate fermentation), hexokinase/citrate synthase (glucose phosphorylation/citric acid cycle) and 3-hydroxyacyl-CoA dehydrogenase/citrate synthase (fatty acid oxidation/citric acid cycle). With respect to the constancy of these ratios, consistent characteristics exist in the organization of the enzyme activity pattern. It is suggested that the more or less invariable coordination of these metabolic systems is not subject to metabolic differentiation. On the contrary, metabolic differentiation is reflected by extreme variations of the following ratios: triose-phosphate dehydrogenase/3-hydroxyacyl-CoA dehydrogenase (glycolysis/fatty acid oxidation), triosephosphate dehydrogenase/citrate synthase (glycolysis/citric acid cycle), lactate dehydrogenase/citrate synthase (lactate fermentation/citric acid cycle), phosphorylase/hexokinase (glycogenolysis/glucose phosphorylation), and hexosediphosphatase/hexokinase (gluconeogenesis/glucose phosphorylation). These variable enzyme activity ratios are discriminative magnitudes and make it possible to discern distinct metabolic types of muscle. White (fast) muscle is characterized by high capacities of glycogenolysis, glycolysis and lactate fermentation, whereas the capacities of glucose phosphorylation, citric acid cycle and fatty acid oxidation are low. Red (slow) muscles, heart and smooth muscle show inverse characteristics. In white (fast) muscle, high activities of hexosediphosphatase and of mitochondrial glycerolphosphate dehydrogenase indicate that gluconeogenesis starting from glycerolphosphate or triosephosphate is probably important in this muscle type, and compensates for its low capacity of glucose phosphorylation.
Article
Early studies of subjective force estimates for short time work on a bicycle ergometer are reviewed. Results showed that perceived pedal resistance followed a positively accelerating function with an exponent of 1.6. A model for inter individual comparisons using subjective range as a frame of reference is explained. Results of two experiments comparing four different rating methods are reported. Two methods involved the original Borg Scale, and a variation, one graded from 1 to 21 and the other from 6 to 20. The third method utilized a line scale while the fourth scale was graded from 1 to 9 with 2 anchored by the expression 'Not At All Stressful' and 8 with 'Very, Very Stressful'. These two experiments show that good correlations between heart rates and ratings are obtained independent of which scale is used. Since the Borg (6 to 20) Scale is the one most often used and gives values that grow fairly linear with work load and heart rate it is proposed that this scale be used in most cases.
Article
In an earlier study, we reported close relationships between marathon running performance and the running velocity (V) at which the "onset of blood lactate accumulation" (VOBLA) occurs in a group of marathon runners. Using biopsy material from the m. vastus lateralis of the same subjects (n = 19), we have evaluated the relationship of VOBLA to different muscle enzyme activities together with muscle fiber composition and capillary density in the present study. The activities of lactate dehydrogenase (LDH EC 1.1.1.27), phosphofructokinase (PFK EC 2.7.1.11), and citrate synthase (CS EC 4.1.3.7) were determined. VOBLA was negatively correlated to LDH (r = -0.54) and PFK/CS (r = -0.68). Using multiple regression analysis, the PFK/CS ratio together with the capillary density accounted for 61% of the variation in VOBLA. Absolute training kilometrage was the most significant variable measured and accounted for 77% of the variation in VOBLA. Subjects were divided into elite runners (n = 6) and nonelite runners (n = 13) for an additional analysis of the relationship between VOBLA and the ratios of PFK/CS or LDH/CS. Significant relationships between VOBLA and the ratios were observed only in the nonelite runners (r = -0.77 and -0.66, respectively). The vertical distances between the regression lines for these two subject groups could not be explained only on the basis of the enzyme activity ratios. A greater adaptation to fat combustion in the elite runners might explain the disproportionally high VOBLA in relation to the PFK/CS or LDH/CS activity ratios.
Article
The physiological factors that relate to 20-km performance were studied in eight competitive racewalkers. The racewalking velocity at the blood lactate threshold (LT) during steady-state exercise was highly correlated to racewalking pace (r = 0.94) and predicted performance times to within 0.6%, which agrees with previous observations on runners. The two factors that contribute to velocity at LT are O2 uptake at LT (VO2 at LT) and submaximal racewalking economy (measured as the VO2 at a standard velocity). Oxygen uptake at LT was significantly correlated (r = 0.89) to performance in the racewalkers in the present investigation, which agrees with previous observations of runners. Submaximal economy was significantly correlated to performance in the racewalkers (r = -0.82). Maximal oxygen uptake measured during racewalking was not significantly correlated (r = 0.62) to performance. These data indicate that the velocity at LT correlates closely to performance in racewalkers and that the factor of submaximal economy, which partly determines velocity at LT, is related more to performance ability in racewalking than was previously observed in running.
Muscle force recovery from short term intense exercise was examined in 16 physically active men. They performed 50 consecutive maximal voluntary knee extensions. Following a 40-s rest period five additional maximal contractions were executed. The decrease in torque during the 50 contractions and the peak torque during the five contractions relative to initial torque were used as indices for fatigue and recovery, respectively. Venous blood samples were collected repeatedly up to 8 min post exercise for subsequent lactate analyses. Muscle biopsies were obtained from m. vastus lateralis and analysed for fiber type composition, fiber area, and capillary density. Peak torque decreased 67 (range 47-82%) as a result of the repeated contractions. Following recovery, peak torque averaged 70 (47-86%) of the initial value. Lactate concentration after the 50 contractions was 2.9 +/- 1.3 mmol X 1(-1) and the peak post exercise value averaged 8.7 +/- 2.1 mmol X 1(-1). Fatigue and recovery respectively were correlated with capillary density (r = -0.71 and 0.69) but not with fiber type distribution. A relationship was demonstrated between capillary density and post exercise/peak post exercise blood lactate concentration (r = 0.64). Based on the present findings it is suggested that lactate elimination from the exercising muscle is partly dependent upon the capillary supply and subsequently influences the rate of muscle force recovery.
Article
Eight men were studied before and after a 12-wk exercise program to determine the effect of training on blood lactate levels during submaximal exercise. The training elicited a 26% increase in maximum O2 uptake (VO2max). Lactate concentrations at the same relative exercise intensities in the 55-75% of VO2max range were significantly lower after training. A significantly higher relative exercise intensity was needed to elicit a given lactate level in the 1.5- to 3.0-mM range after training. O2 uptake at the work rate required to raise blood lactate to 2.5 mM was 39% higher after training. A blood lactate of 2.5 mM was attained at 68 +/- 4% VO2max before and 75 +/- 3% of VO2max after training. Eight competitive runners required an even higher relative work rate (83 +/- 2% of VO2max) to attain a blood lactate of 2.5 mM. These data provide evidence that the adaptations to training that result in an increase in VO2max are, to some degree, independent of those responsible for the lower blood lactate levels during submaximal exercise.
Article
Six patients with ischemic heart disease who had exercised intensely for longer than 1 yr appeared to have a disproportionately high capacity for endurance exercise relative to VO2 max. They were compared with healthy runners of the same age (mean 55 yr) with similar training programs (6-12 km/day, 5 day/wk). The trained patients had a significantly (P less than 0.05) lower maximal cardiac output (-17%) and VO2 max (-18%, 37 vs. 45 ml . kg-1 . min-1). Despite their lower VO2 max, the trained patients were able to run 8 km at the same speed as the normal runners (approximately 189 m/min). The trained patients' ability to keep pace with the normal subjects was apparently due to a very high lactate threshold (LT) relative to VO2 max. The patients' LT (lactate 1 mM above base line) occurred at a treadmill running speed of 176 m/min, which elicited 100% of their VO2 max, compared with a LT at 178 m/min and 84% of VO2 max in the normal subjects (P less than 0.01). Our results show that some individuals with VO2 max limited by impaired cardiac function can undergo adaptations to training that enable them to maintain close to a metabolic steady state during exercise that elicits VO2 max.
Article
To investigate the relationship between the maximal steady state (MSS) and selected running events, seven males (mean = 37.6 years) who were experienced competitive distance runners were studied. From a series of 10-min steady-state treadmill runs, MSS (treadmill velocity, VO2, or heart rate where lactic acid concentration was 2.2 mM/L of venous blood) was determined for all subjects. Treadmill velocity at MSS averaged 258.9 +/- 29.0 m/min. The subjects subsequently performed maximal time trials or races at 13.7 m (15 yd), 45.7 m (50 yd), 402.3 m (440 yd), 3.22 km (2 miles), 8.05 km (5 miles), 16.09 km (10 miles), and 20 km (12.44 miles). Running paces for the 402.3-m, 3.22-km, 8.05-km, 16.09-km, and 20-km distances were all correlated significantly with the treadmill pace at MSS (r = 0.84 to 0.995). The highest correlation was between the MSS treadmill velocity and the 8.05-km pace. The mean for a 6.44-km (4 miles) flat section of the 16.09-km run was identical to the mean treadmill velocity at MSS (258.9 m/min). These data indicate that the pace for essentially aerobic events (3.22 km to 20 km) can be closely approximated by knowledge of a runner's MSS, or conversely that the MSS can be predicted very closely from the pace during an all-out 3.22-km, 8.05 km, 16.09-km, or 20-km run.
Article
The effects of endurance training on aerobic power, and the relationship between aerobic power and running performance were investigated in 11 junior runners over a period of 5-to-7 years, starting from the age of 14. Aerobic power was measured using treadmill running and a protocol that involved increasing speed. The six subjects who comprised group I were those who continued competitive training, while the five in group II had stopped training by the age of 18. The subjects in group I demonstrated greater aerobic power (l x min-1) and better running performance than those in group II. Aerobic power for group I increased from 3.54 l x min-1 (65.4 ml x kg-1 x min-1) to 4.49 l x min-1 (75.5 ml x kg-1 x min-1) between the ages of 14.8 and 18.8 yr. The increase in l x min-1 and ml x kg-1 x min-1 was statistically significant (p less than 0.01, p less than 0.05). The greatest aerobic power found in subject A corresponds to the data from world-class runners: 3.63 l x min-1 (61.5 ml x kg-1 x min-1) at age 14.7 yr; 4.67 l x min-1 (74.6 ml x kg-1 x min-1) at 17.8 yr; and 5.04 l x min-1 (76.3 ml x kg-1 x min-1) at 20.7 yr. After their training was discontinued, aerobic power for those in group II decreased to the level of ordinary schoolboys. Improvement in running performance was closely related to the increase of aerobic power in l x min-1. Superior running performance seems to be associated with high aerobic power in l x min-1, rather than in ml x kg-1 x min-1 for junior runners.
Article
This study was designed to examine the interrelationships among endurance running performance (marathon), the exercise intensity at which the "onset of blood lactate accumulation" (OBLA) occurs training volume, and muscle fiber characteristics. In conjunction with Stockholm's Marathon (1979), 18 male subjects underwent a test to determine the relationship between treadmill running velocity and blood lactate accumulation. The velocity at which a blood lactate accumulation of 4 mmol x l-1 occurred was referred to as the VOBLA. The m. vastus lateralis was biopsied and muscle fiber type distribution (% slow twitch, ST) and capillary density determined. With marathon running velocity (VM) as the dependent variable, multiple regression analysis showed that VOBLA accounted for 92% of the variation in VM, and VOBLA plus training volume prior to the marathon accounted for 96% of this variation. All performance variables were positively correlated to % ST muscle fiber distribution (r = 0.55-0.69) and capillary density (r = 052-0.63). Thus, marathon running performance was closely related to VOBLA and to the ability to run at a pace close to that velocity during the race. These properties were in turn related to % ST, capillary density, and training volume.
Article
Laboratory and field assessments were made on eighteen male distance runners. Performance data were obtained for distances of 3.2, 9.7, 15, 19.3 km (n = 18) and the marathon (n = 13). Muscle fiber composition expressed as percent of slow twitch fibers (%ST), maximal oxygen consumption (VO2max), running economy (VO2 for a treadmill velocity of 268 m/min), and the VO2 and treadmill velocity corresponding to the onset of plasma lactate accumulation (OPLA) were determined for each subject. %ST (R > or equal to .47), VO2max (r > or equal to .83), running economy (r > or equal to .49), VO2 in ml/kg min corresponding to the OPLA (r > or equal to .91) and the treadmill velocity corresponding to OPLA (r > or equal to .91) were significantly (p < .05) related to performance at all distances. Multiple regression analysis showed that the treadmill velocity corresponding to the OPLA was most closely related to performance and the addition of other factors did not significantly raise the multiple R values suggesting that these other variables may interact with the purpose of keeping plasma lactates low during distance races. The slowest and fastest marathoners ran their marathons 7 and 3 m/min faster than their treadmill velocities corresponding to their OPLA which indicates that this relationship is independent of the competitive level of the runner. Runners appear to set a race pace which allows the utilization of the largest possible VO2 which just avoids the exponential rise in plasma lactate.
Perceived exertion: a note on history and methods Three "myosin ATPase" systems: the nature of their pH lability and sulfhydryl dependence
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BORG, G. A. Perceived exertion: a note on history and methods. Med. Sci. Sports 5: 90-93, 1973. 5. BROOKE, M. H., AND K. K. KAISER. Three "myosin ATPase" systems: the nature of their pH lability and sulfhydryl dependence. J. Hi&o&m. Cytochem. 18: 670-672,197O.
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Plasma lactate accumulation and distance running 37 Muscle fiber types and size in performance trained and untrained muscles of elite athletes
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(+)-lactate. Determination with lactate dehydrogenase and NAD
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Capillary density in skeletal muscle of man
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Glycogen utilization in leg muscles of men during level and uphill running
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Blood lactate: implications for training and sport performance
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The use of laboratory test results with long distance runners
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Mean arterial pressure, O,-uptake, and muscle force time during dynamic and rhythmic-static exercise in men with high percentages of fast and slow twitch fibers
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