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Footwear affects the gearing at the ankle and knee joints during running

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The objective of the study was to investigate the adjustment of running mechanics by wearing five different types of running shoes on tartan compared to barefoot running on grass focusing on the gearing at the ankle and knee joints. The gear ratio, defined as the ratio of the moment arm of the ground reaction force (GRF) to the moment arm of the counteracting muscle tendon unit, is considered to be an indicator of joint loading and mechanical efficiency. Lower extremity kinematics and kinetics of 14 healthy volunteers were quantified three dimensionally and compared between running in shoes on tartan and barefoot on grass. Results showed no differences for the gear ratios and resultant joint moments for the ankle and knee joints across the five different shoes, but showed that wearing running shoes affects the gearing at the ankle and knee joints due to changes in the moment arm of the GRF. During barefoot running the ankle joint showed a higher gear ratio in early stance and a lower ratio in the late stance, while the gear ratio at the knee joint was lower during midstance compared to shod running. Because the moment arms of the counteracting muscle tendon units did not change, the determinants of the gear ratios were the moment arms of the GRF's. The results imply higher mechanical stress in shod running for the knee joint structures during midstance but also indicate an improved mechanical advantage in force generation for the ankle extensors during the push-off phase.
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... From a mechanical point of view there are two possible ways to influence the energy storage and release mechanisms in the triceps surae MTU. If running technique is unchanged MTU stiffness may be the main factor but changes in running technique, i.e., a change in the centre of pressure can affect the moment arm of the GRF and with that the gear ratio (Albracht & Arampatzis, 2013;Braunstein et al., 2010). Based on the papers identified in this review (Table 1) it appears that running technique is not changed after training, however, as RE measurements are typically performed on treadmills kinetic changes may not have been fully covered in these studies. ...
... With reference to a study by Braunstein et al. (2010), footwear offers the possibility to alter the gear ratio at the ankle and knee joint in certain phases of the ground contact (Braunstein et al., 2010). It is thus possible that midsole hardness and geometry, as well as a combination thereof, may provide subtle changes in muscle force generation over time which in certain instances, i.e., in some individuals, may lead to a better economy. ...
... With reference to a study by Braunstein et al. (2010), footwear offers the possibility to alter the gear ratio at the ankle and knee joint in certain phases of the ground contact (Braunstein et al., 2010). It is thus possible that midsole hardness and geometry, as well as a combination thereof, may provide subtle changes in muscle force generation over time which in certain instances, i.e., in some individuals, may lead to a better economy. ...
Article
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Context: This article systematically reviews the available literature on biomechanically motivated interventions to improve running economy aside from conventional endurance training. It was aimed to identify the possible mechanisms behind the potential improvements and to extract principles to guide researchers and coaches in how to make use of this potential. Evidence acquisition: The search strategy yielded 26 intervention papers and four reviews which were suitable for inclusion. Results: It was concluded that plyometric and strength training protocols were consistently beneficial to reduce the oxygen consumption per distance traveled in steady state running showing an average effect size of 3.8%. Footwear interventions showed smaller effects of 1.9% on average but still may offer considerable improvements which can potentially be applied immediately. Conclusions: It was suggested that the energy consumption savings achieved by footwear interventions are not realizable by energy return mechanisms of the footwear alone. It is most likely that footwear assists to improve RE by optimizing energy storage and return mechanisms within the biological system. Future research should aim at verifying this interplay to provide more efficient training programs as well as footwear which ameliorates the utilization of the mechanisms embedded within the human locomotor system.
... Lastly, the principle of optimising for muscle function suggests that the variable gearing during running (i.e. the ratio between muscle-tendon unit moment arm and GRF moment arm relative to a joint centre) (Carrier et al., 1994) can be altered by changing the MBS of footwear so that muscle forces are generated at slower speeds (Braunstein et al., 2010;Willwacher et al., 2014). This is speculated to reduce the muscle energy cost of generating the necessary forces to execute an athletic task (Roberts et al., 1998;Braunstein et al., 2010;Willwacher et al., 2014). ...
... Lastly, the principle of optimising for muscle function suggests that the variable gearing during running (i.e. the ratio between muscle-tendon unit moment arm and GRF moment arm relative to a joint centre) (Carrier et al., 1994) can be altered by changing the MBS of footwear so that muscle forces are generated at slower speeds (Braunstein et al., 2010;Willwacher et al., 2014). This is speculated to reduce the muscle energy cost of generating the necessary forces to execute an athletic task (Roberts et al., 1998;Braunstein et al., 2010;Willwacher et al., 2014). ...
... Previous studies have proposed that running with increased MBS resulted in better athletic performance because it allowed the major ankle plantarflexor muscles (e.g. triceps surae) to generate force more economically (Braunstein et al., 2010;Takahashi et al., 2016). For this reason, it was hypothesised that running in the stiff condition would result in lower shortening velocities of the sMTU. ...
Thesis
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The latest records set during long-distance running competitions have been attributed to recent footwear midsole innovations. One of these midsole innovations that has been claimed to have large effects on biomechanical, physiological, and performance variables is the use of a carbon fibre plate to increase the longitudinal bending stiffness of a shoe. Several mechanisms were proposed to be associated with performance improvements when running in footwear with carbon fibre plates. One of these mechanisms, the principle of optimising muscle function is currently not well understood. Therefore, this thesis aimed to investigate the effects of midsole bending stiffness of athletic footwear on muscle and muscle-tendon unit function in running. The first part of this thesis showed that running in stiff footwear resulted in a redistribution of positive work from proximal to distal lower limb joints. Specifically, it was found that a fatigue-induced redistribution of joint work from distal to proximal joints can be delayed when running in stiff footwear. The second part of this thesis dealt with the shortening velocities of muscle-tendon units. Estimated shank muscle-tendon unit shortening velocities were reduced when running in stiffer shoes. Experimental results using ultrasound imaging of the gastrocnemius medialis muscle revealed that the muscle shortened to a lesser extent and with lower average velocities in stiff running footwear. These findings could have implications for long-distance running performance. Positive work generation at more distal joints (i.e., ankle) may result in lower active muscle volume, which has been shown to be the main determinant of changes in the energetic cost of running. Slower shortening velocities of the gastrocnemius medialis could allow the muscle to operate on a more favourable position on its force-velocity relationship. This could allow for more economical force generation for a longer period during long-distance running. Altered muscle function could be a source of improved performance when running in stiff shoes.
... Previous literature addressed the principle of storing and returning energy in the midsole due to longitudinal bending, but the results are inconclusive, as some studies suggested that the carbon fibre plates are able to store and return elastic energy indicated by more positive work performed at the MTP joint [4,5] or increased ground reaction forces (GRF) [5], whereas other studies suggested that other footwear features are the primary cause of these observed increases in positive work done at the MTP joint [6]. Lastly, the principle of optimising for muscle function suggests that the variable gearing during running (i.e. the ratio between muscle-tendon unit moment arm and GRF moment arm relative to a joint centre) [21] can be altered by changing the MBS of footwear so that muscle forces are generated at slower speeds [14,22]. This is speculated to reduce the muscle energy cost of generating the necessary forces to execute an athletic task [14,22,23]. ...
... Lastly, the principle of optimising for muscle function suggests that the variable gearing during running (i.e. the ratio between muscle-tendon unit moment arm and GRF moment arm relative to a joint centre) [21] can be altered by changing the MBS of footwear so that muscle forces are generated at slower speeds [14,22]. This is speculated to reduce the muscle energy cost of generating the necessary forces to execute an athletic task [14,22,23]. ...
... Previous studies have proposed that running with increased MBS resulted in better athletic performance because it allowed the major ankle plantarflexor muscles (e.g. triceps surae) to generate force more economically [15,22]. For this reason, it was hypothesised that running in the stiff condition would result in lower shortening velocities of the sMTU. ...
Article
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Background Individual compliances of the foot-shoe interface have been suggested to store and release elastic strain energy via ligamentous and tendinous structures or by increased midsole bending stiffness (MBS), compression stiffness, and resilience of running shoes. It is unknown, however, how these compliances interact with each other when the MBS of a running shoe is increased. The purpose of this study was to investigate how structures of the foot-shoe interface are influenced during running by changes to the MBS of sport shoes. Methods A randomised crossover trial was performed, where thirteen male, recreational runners ran on an instrumented treadmill at 3.5 m∙s-1 while motion capture was used to estimate foot arch, plantar muscle-tendon unit (pMTU) and shank muscle-tendon unit (sMTU) behaviour in two conditions: (1) control shoe and (2) the same shoe with carbon fibre plates inserted to increase the MBS. Results Running in a shoe with increased MBS resulted in less deformation of the arch (mean ± SD; stiff: 7.26 ± 1.78°, control: 8.84 ± 2.87°, p ≤ 0.05), reduced pMTU shortening (stiff: 4.39 ± 1.59 mm, control: 6.46 ± 1.42 mm, p ≤ 0.01), and lower shortening velocities of the pMTU (stiff: -0.21 ± 0.03 m∙s-1, control: -0.30 ± 0.05 m∙s-1, p ≤ 0.01) and sMTU (stiff: -0.35 ± 0.08 m∙s-1, control: -0.45 ± 0.11 m∙s-1, p ≤ 0.001) compared to a control condition. The positive and net work performed at the arch and pMTU, and the net work at the sMTU were significantly lower in the stiff compared to the control condition. Conclusion The findings of this study showed that if a compliance of the footshoe interface is altered during running (e.g., by increasing the MBS of a shoe), the mechanics of other structures change as well. This could potentially affect long distance running performance.
... Anecdotal evidence from experienced coaches suggests that barefoot running on softer surfaces such as grass has been used as a training regimen for the strengthening of extrinsic and intrinsic foot muscles by track and field coaches already decades ago (1). More recently, it was shown that running in minimal footwear induced increases in strength and cross sectional areas of extrinsic and intrinsic foot muscles compared with training in conventional footwear (2,5,10,11,23,37). ...
... Barefoot running resulted in a more plantarflexed foot strike pattern, which has been found in several earlier publications (7,8,29). Braunstein et al. (1) showed that an altered foot strike pattern in barefoot running led to increased ground reaction force lever arms at the ankle and reduced lever arms at the knee. This seems to be the mechanism explaining the observed changes in joint moment amplitudes in the current study. ...
Article
Willwacher, S, Fischer, KM, Rohr, E, Trudeau, MB, Hamill, J, and Brüggemann, G-P. Surface stiffness and footwear affect the loading stimulus for lower extremity muscles when running. J Strength Cond Res XX(X): 000-000, 2020-Running in minimal footwear or barefoot can improve foot muscle strength. Muscles spanning the foot and ankle joints have the potential to improve performance and to reduce overuse injury risk. Surface stiffness or footwear use could modify the intensity of training stimuli acting on lower extremity joints during running. The purpose of this study was to systematically investigate external ankle, knee, and hip joint moments during shod and barefoot running while considering the stiffness of the running surface. Two footwear conditions (barefoot and neutral running shoe) and 4 surface conditions (Tartan, Tartan + Ethylene Vinyl Acetate [EVA] foam, Tartan + artificial turf, Tartan + EVA foam + artificial turf) were tested at 3.5 m·s. Repeated measures analysis of variance revealed that barefoot running in general and running barefoot on harder surfaces increased and decreased ankle (between +5 and +26%) and knee (between 0 and -11%) joint moments, respectively. Averaged over all surfaces, running barefoot was characterized by a 6.8° more plantarflexed foot strike pattern compared with running shod. Foot strike patterns were more plantarflexed on harder surfaces; the effects, however, were less than 3°. Most surface effects were stronger in barefoot compared with shod running. Surface stiffness may be used to modulate the loading intensity of lower extremity muscles (in particular extrinsic and intrinsic foot muscles) during running. These results need to be considered when coaches advise barefoot running as a method to improve the strength of extrinsic and intrinsic foot muscles or when trying to reduce knee joint loading.
... One of the most important influences on injury mechanics and kinematics of the lower limb is footwear [15,42,43]. Of particular interest is the effect footwear can have on gait as any change in gait pattern from what the body is accustomed to is associated with an increased risk of injury [44]. ...
... Appropriately, cushioned footwear redistributes and reduces plantar pressure [13,15], while inadequate shock absorption will transmit large forces through the body, potentially resulting in injury [13,15,45,46,55,56]. These forces can also result in gait changes by the wearer in an attempt to attenuate the force [42,57]. When running in minimally cushioned shoes with a predominately rearfoot strike, the ankle is less dorsiflexed (i.e. ...
Article
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Injuries are common within military populations, with high incidence rates well established in the literature. Injuries cause a substantial number of working days lost, a significant cost through compensation claims and an increased risk of attrition. In an effort to address this, a considerable amount of research has gone into identifying the most prevalent types of injury and their associated risk factors. Collective evidence suggests that training and equipment contribute to a large proportion of the injuries sustained. In particular, the large loads borne by soldiers, the high intensity training programs and the influence of footwear have been identified as significant causative factors of lower limb injury in military populations. A number of preventative strategies have been developed within military bodies around the world to address these issues. The relative success of these strategies is highly variable; however, with advancements in technology, new approaches will become available and existing strategies may become more effective.
... We therefore confirmed that subjects could use each foot strike pattern appropriately for each trial. Previously, FFS, MFS, and RFS were defined as conditions where the GRF application points were in the front one-third, middle one-third, and rear one-third of foot length at the instance of foot contact, respectively [4]. Therefore, the ratio of the foot length and the heel-to-GRF application point length at the instance of foot contact defined those foot strike patterns. ...
... Young male runners participated in this study, and they were asked to perform barefoot running along a level runway at 3.3 m · s − 1 . Gender [11], age [9,37], footwear [42], ground surface [4], gradient [13], and running speed [28] may have potential to affect present results. Some studies did not determine the forces applied to injured regions but ground reaction force and/or joint moment. ...
Article
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Permissions and Reprints Abstract Ground reaction force is often used to predict the potential risk of injuries but may not coincide with the forces applied to commonly injured regions of the foot. This study examined the forces applied to the foot, and the associated moment arms made by three foot strike patterns. 10 male runners ran barefoot along a runway at 3.3 m/s using forefoot, midfoot, and rearfoot strikes. The Achilles tendon and ground reaction force moment arms represented the shortest distance between the ankle joint axis and the line of action of each force. The Achilles tendon and joint reaction forces were calculated by solving equations of foot motion. The Achilles tendon and joint reaction forces were greatest for the forefoot strike (2 194 and 3 137 N), followed by the midfoot strike (1 929 and 2 853 N), and the rearfoot strike (1 526 and 2 394 N). The ground reaction force moment arm was greater for the forefoot strike than for the other foot strikes, and was greater for the midfoot strike than for the rearfoot strike. Meanwhile, there were no differences in the Achilles tendon moment arm among all foot strikes. These differences were attributed mainly to differences in the ground reaction force moment arm among the three foot strike patterns. Key word running - moment arm - Achilles tendon force - joint reaction force - musculoskeletal injury
... These results agree with previous studies (De Wit et al., 2000;Lieberman et al., 2010) on the comparison of shod and barefoot running. It is well known that the gear ratios of the ankle joint muscles [i.e., the ratio between the ground reaction force and the muscle force moment arms Carrier et al., 1994] do not only vary through the running stance phase (Carrier et al., 1994), but also when switching from the shod to the barefoot condition (Braunstein et al., 2010). In the last 20% of the stance phase the gear ratio at the ankle joint is lower during barefoot compared to shod running (Braunstein et al., 2010). ...
... It is well known that the gear ratios of the ankle joint muscles [i.e., the ratio between the ground reaction force and the muscle force moment arms Carrier et al., 1994] do not only vary through the running stance phase (Carrier et al., 1994), but also when switching from the shod to the barefoot condition (Braunstein et al., 2010). In the last 20% of the stance phase the gear ratio at the ankle joint is lower during barefoot compared to shod running (Braunstein et al., 2010). Lower gear ratios at the ankle joint decrease the contact time while running (Lee and Piazza, 2009) and provide an explanation for the shorter contact times found during barefoot running. ...
... These results agree with previous studies (De Wit et al., 2000;Lieberman et al., 2010) on the comparison of shod and barefoot running. It is well known that the gear ratios of the ankle joint muscles [i.e., the ratio between the ground reaction force and the muscle force moment arms Carrier et al., 1994] do not only vary through the running stance phase (Carrier et al., 1994), but also when switching from the shod to the barefoot condition (Braunstein et al., 2010). In the last 20% of the stance phase the gear ratio at the ankle joint is lower during barefoot compared to shod running (Braunstein et al., 2010). ...
... It is well known that the gear ratios of the ankle joint muscles [i.e., the ratio between the ground reaction force and the muscle force moment arms Carrier et al., 1994] do not only vary through the running stance phase (Carrier et al., 1994), but also when switching from the shod to the barefoot condition (Braunstein et al., 2010). In the last 20% of the stance phase the gear ratio at the ankle joint is lower during barefoot compared to shod running (Braunstein et al., 2010). Lower gear ratios at the ankle joint decrease the contact time while running (Lee and Piazza, 2009) and provide an explanation for the shorter contact times found during barefoot running. ...
Article
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For most of our history, we predominantly ran barefoot or in minimalist shoes. The advent of modern footwear, however, might have introduced alterations in the motor control of running. The present study investigated shod and barefoot running under the perspective of the modular organization of muscle activation, in order to help addressing the neurophysiological factors underlying human locomotion. On a treadmill, 20 young and healthy inexperienced barefoot runners ran shod and barefoot at preferred speed (2.8±0.4 m/s). Fundamental synergies, containing the time-dependent activation coefficients (motor primitives) and the time-invariant muscle weightings (motor modules), were extracted from 24 ipsilateral electromyographic activities using non-negative matrix factorization. In shod running, the average foot strike pattern was a rearfoot strike, while in barefoot running it was a mid-forefoot strike. In both conditions, five fundamental synergies were enough to describe as many gait cycle phases: weight acceptance, propulsion, arm swing, early swing and late swing. We found the motor primitives to be generally shifted earlier in time during the stance-related phases and later in the swing-related ones in barefoot running. The motor primitive describing the propulsion phase was significantly of shorter duration (peculiarity confirmed by the analysis of the spinal motor output). The arm swing primitive, instead, was significantly wider in the barefoot condition. The motor modules demonstrated analogous organization with some significant differences in the propulsion, arm swing and late swing synergies. Other than to the trivial absence of shoes, the differences might be deputed to the lower ankle gear ratio (and the consequent increased system instability) and to the higher recoil capabilities of the longitudinal foot arch during barefoot compared to shod running.
... Furthermore, each footfall needs to land on the relatively small surface of each step, therefore, successful performance of both stair ascent and decent require body coordination across multiple body segments in order to avoid trips or falls. Overground running has been studied extensively from different points of view [5,6]; a detailed review of early research being provided by Novacheck [7]. ...
... Optical-based motion capture systems and instrumented walkways, which are commonly used for studying gait, are limited by practical challenges in order to appropriately position cameras for the desired motion capture volume. Consequently, past studies of stair climbing focus on the functional walking pace [8][9][10] and have estimated overall energy expenditure [11], basic timing measures [12], and joint angles [6]. ...
Article
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Stair running, both ascending and descending, is a challenging aerobic exercise that many athletes, recreational runners, and soldiers perform during training. Studying biomechanics of stair running over multiple steps has been limited by the practical challenges presented while using optical-based motion tracking systems. We propose using foot-mounted inertial measurement units (IMUs) as a solution as they enable unrestricted motion capture in any environment and without need for external references. In particular, this paper presents methods for estimating foot velocity and trajectory during stair running using foot-mounted IMUs. Computational methods leverage the stationary periods occurring during the stance phase and known stair geometry to estimate foot orientation and trajectory, ultimately used to calculate stride metrics. These calculations, applied to human participant stair running data, reveal performance trends through timing, trajectory, energy, and force stride metrics. We present the results of our analysis of experimental data collected on eleven subjects. Overall, we determine that for either ascending or descending, the stance time is the strongest predictor of speed as shown by its high correlation with stride time.
... The researchers concluded that wearing shoes affects the moment at ankle and knee joints by extending the moment arm of the ground reaction force. Additionally, knee loading was greater in shod running, which can be more painful for those with osteoarthritis or knee injuries [7]. ...
... This difference may also indicate a disturbance in a runner's natural pattern, resulting in higher chances of injury while shod. With an average heel strike, or initial contact, knee angle of 163.5° and standard deviation of 5.6, these measures can be deemed accurate because values agree with the study from University of Cologne finding angles of 160º with a standard deviation of 4 [7]. No significant differences were found when assessing knee angle during heel strike, toe-off and peak stance flexion. ...
Article
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Each year thousands of runners are injured, many incidents being caused by improper form or attire. Prior studies have shown barefoot running to reduce impact loading, contact time, and stride length by encouraging a forefoot striking (FFS) pattern. The aim of this study is to further analyze and compare mechanical characteristics and effects between barefoot and shod running. Data collected from N=11 participants with Qualisys 3D motion tracking system was used to assess applied foot force, inversion and eversion angles, foot plantarflexion, location of the center of pressure of the foot, ankle moment, in addition to moments, forces, and flexion angles of the knee. When barefoot, statistically significant reductions in several parameters, including impact force and peak knee moment were observed which may reduce the overall risk of injury. No significant increase in eversion was observed. By performing this biomechanical analysis on barefoot running, researchers conclude that barefoot style running results in a safe gait pattern. Future impacts of this research may directly affect current training regimens. Increasing awareness of barefoot running may inspire others to verify this study and determine to what degree running related injuries are preventable. Key Words: Biomechanics, running, barefoot
... 2,8,11,16,35,42 These adaptations include changing from a rearfoot to more anterior foot strike pattern (midfoot or forefoot strike). 3,5,18,33 Furthermore, it was reported that running barefoot as compared with shod was associated with reduced foot and ankle dorsiflexion at ground contact, increased knee flexion at ground contact, reduced stride length, higher cadence, reduced vertical ground-reaction forces, reduced peak knee extension and flexion, and reduced peak ankle internal rotation. 2,3,5,8,11,14 While moderate evidence was reported for reduced ground-reaction forces in barefoot running, conflicting results were demonstrated for loading rates in a habitually barefoot or shod population. ...
... 3,5,18,33 Furthermore, it was reported that running barefoot as compared with shod was associated with reduced foot and ankle dorsiflexion at ground contact, increased knee flexion at ground contact, reduced stride length, higher cadence, reduced vertical ground-reaction forces, reduced peak knee extension and flexion, and reduced peak ankle internal rotation. 2,3,5,8,11,14 While moderate evidence was reported for reduced ground-reaction forces in barefoot running, conflicting results were demonstrated for loading rates in a habitually barefoot or shod population. 8,18,33,36 The habituation to barefoot or shod running has been discussed as a reason for these opposite findings. ...
Article
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Background: Previous studies have shown that changing acutely from shod to barefoot running induces several changes to running biomechanics, such as altered ankle kinematics, reduced ground-reaction forces, and reduced loading rates. However, uncertainty exists whether these effects still exist after a short period of barefoot running habituation. Purpose/hypothesis: The purpose was to investigate the effects of a habituation to barefoot versus shod running on running biomechanics. It was hypothesized that a habituation to barefoot running would induce different adaptations of running kinetics and kinematics as compared with a habituation to cushioned footwear running or no habituation. Study design: Controlled laboratory study. Methods: Young, physically active adults without experience in barefoot running were randomly allocated to a barefoot habituation group, a cushioned footwear group, or a passive control group. The 8-week intervention in the barefoot and footwear groups consisted of 15 minutes of treadmill running at 70% of VO2 max (maximal oxygen consumption) velocity per weekly session in the allocated footwear. Before and after the intervention period, a 3-dimensional biomechanical analysis for barefoot and shod running was conducted on an instrumented treadmill. The passive control group did not receive any intervention but was also tested prior to and after 8 weeks. Pre- to posttest changes in kinematics, kinetics, and spatiotemporal parameters were then analyzed with a mixed effects model. Results: Of the 60 included participants (51.7% female; mean ± SD age, 25.4 ± 3.3 years; body mass index, 22.6 ± 2.1 kg·m-2), 53 completed the study (19 in the barefoot habituation group, 18 in the shod habituation group, and 16 in the passive control group). Acutely, running barefoot versus shod influenced foot strike index and ankle, foot, and knee angles at ground contact ( P < .001), as well as vertical average loading rate ( P = .003), peak force ( P < .001), contact time ( P < .001), flight time ( P < .001), step length ( P < .001), and cadence ( P < .001). No differences were found for average force ( P = .391). After the barefoot habituation period, participants exhibited more anterior foot placement ( P = .006) when running barefoot, while no changes were observed in the footwear condition. Furthermore, barefoot habituation increased the vertical average loading rates in both conditions (barefoot, P = .01; shod, P = .003) and average vertical ground-reaction forces for shod running ( P = .039). All other outcomes (ankle, foot, and knee angles at ground contact and flight time, contact time, cadence, and peak forces) did not change significantly after the 8-week habituation. Conclusion: Changing acutely from shod to barefoot running in a habitually shod population increased the foot strike index and reduced ground-reaction force and loading rates. After the habituation to barefoot running, the foot strike index was further increased, while the force and average loading rates also increased as compared with the acute barefoot running situation. The increased average loading rate is contradictory to other studies on acute adaptations of barefoot running. Clinical relevance: A habituation to barefoot running led to increased vertical average loading rates. This finding was unexpected and questions the generalizability of acute adaptations to long-term barefoot running. Sports medicine professionals should consider these adaptations in their recommendations regarding barefoot running as a possible measure for running injury prevention. Registration: DRKS00011073 (German Clinical Trial Register).
... These results agree with previous studies 204,281 on the comparison of shod and barefoot running. It is well known that the gear ratios of the ankle joint muscles (i.e. the ratio between the ground reaction force and the muscle force moment arms 151 ) do not only vary through the running stance phase 151 , but also when switching from the shod to the barefoot condition 230 . In the last 20% of the stance phase the gear ratio at the ankle joint is lower during barefoot compared to shod running 230 . ...
... It is well known that the gear ratios of the ankle joint muscles (i.e. the ratio between the ground reaction force and the muscle force moment arms 151 ) do not only vary through the running stance phase 151 , but also when switching from the shod to the barefoot condition 230 . In the last 20% of the stance phase the gear ratio at the ankle joint is lower during barefoot compared to shod running 230 . Lower gear ratios at the ankle joint decrease the contact time while running 282 and provide an explanation for the shorter contact times found during barefoot running. ...
Thesis
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The need to move over uneven, continuously changing terrains is part of our daily life. Thus, the central nervous system must integrate an augmented amount of information in order to be able to cope with the unpredictability of external disturbances. A consequence of this increased demand might be a flexible recombination of the modular organisation of movement creation and control. At the expense of motion’s accuracy, it is possible that the system responds by increasing its control’s robustness (i.e. ability to cope with errors). However, the strategies employed by the central nervous system to organise movement are still poorly understood. One possibility is that movements are constructed through a small amount of linearly combined patterns of activations, called muscle synergies. Amongst the several possibilities of perturbing locomotion, the removal of footwear and the use of uneven surfaces are two valid options. In a first step, I conducted a thorough analysis of the methodologies useful for a) the evaluation of spatiotemporal gait parameters using plantar pressure distribution data and b) the extraction of muscle synergies using non-negative matrix factorisation. Afterwards, I analysed the modular organisation of c) shod and barefoot running and d) walking and running over an even- and an uneven-surface treadmill. The modular organisation of locomotion, assessed through the extraction of muscle synergies, changed when perturbations were introduced. Compared to the shod condition, barefoot running underwent, mostly due to the different foot strike pattern, a reorganisation of the time-independent coefficients (motor modules) and a time-shift of the time-dependent muscle activation patterns (motor primitives). Uneven-surface locomotion, compared to even-surface, conserved motor modules, while motor primitives were generally wider, confirming the idea of an increased robustness in motor control during unsteady locomotion.
... Previous studies have discussed plantar pressures when running and performing other specific sports movements on different sports surfaces [2] [3] [9] [10] [12], identifying impact forces and lower extremity joint angle characteristics during running on different sports surfaces can help to reveal risk factors related to sports injury. It is assumed that peak impact force can be reduced when acting on a surface having an increased cushioning property. ...
... In previous studies, the running speed was defined as self-selected by participants [14] [8], however, running speed was shown to be a contributing factor to the presented kinematics [12] [15] [16], In this study, the running speed of each participant was controlled at 2.8 ± 0.2 m/s, and exclude the impact of long-distance running speed on the study [17]. The result exhibited that the largest peak ...
Article
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Running is one of the most accessible physical activities and long-distance running has attracted extensive attention in the past several years. While the incidence of running injuries, especially to the lower extremities, has increased. The objective of this study was to investigate the differences in ground reaction forces (GRF) and kinematic param between long-distance runners before and after long-distance running on treadmill (TM), asphalt road (AR), and plastic track (PT). Eight-camera Vicon motion analysis system was used to measure the hip, knee and ankle motion param of 10 healthy male subjects at a speed of 2.8 ± 0.2m/s. The hip, knee and ankle kinematics and the relationship of joint angles of lower limbs in the sagittal plane, coronal plane and transversal plane were analyzed. Ground reaction force (GRF) was collected using an AMTI force platform. The results showed that there were no significant differences in GRF and average loading rate (VALR). There was no significant difference in the range of motion (ROM) of ankle and hip after long-distance running on three surfaces compared to pre-test. Compared with stance-period of pre-test, the stance-period of AR and PT were significantly longer. Post hoc analyses exhibited the stance-period of AR and PT were longer than TM. In conclusion, runners can adjust different joints angles to maintain a similar GRF during long-distance running on different sports surfaces.
... The benefits of minimalist shoe support (less cushioning and weight, greater flexibility) for maintaining and developing natural running patterns have been widely reported for younger adults. 7,8 The main purpose of this preliminary study was to investigate the effects of minimalist shoes on walking gait patterns and balance in older adults. Twenty-eight healthy, community-dwelling, physically active adults (mean age 66 AE 6.4, range 52-76) were tested under three conditions in random and counterbalanced order: barefoot, minimalist (barfußleguano premium, Leguano GmbH, Sankt Augustin, Germany), and standard cushioned (Asics Galaxy, Onitsuka Co., Ltd., Kobe, Japan) shoes. ...
... Cognitive evaluation included the MMSE 7 and Trail-Making Test B (TMT-B). 8 Demographic information was collected according to self-report and corroborated with caregivers on age, number of prescribed medications, comorbidities, and basic and instrumental activities of daily living. ...
... The fundamental objectives of running shoes are stability [14] and cushioning [15,16], especially under the heel since this receives the initial impact [17]. At each heel strike, the runner is subjected to ground reaction forces that are approximately 1.5-3 times the body weight [15,18]. ...
Article
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Running shoes typically have a lifespan of 300–1000 km, and the plantar pressure pattern during running may change as the shoe wears. So, the aim of this study was to determine the variation of plantar pressures with shoe wear, and the runner’s subjective sensation. Maximun Plantar Pressures (MMP) were measured from 33 male recreational runners at three times during a training season (beginning, 350 km, and 700 km) using the Biofoot/IBV® in-shoe system (Biofoot/IBV®, Valencia, Spain). All the runners wore the same shoes (New Balance® 738, Boston, MA, USA) during this period, and performed similar training. The zones supporting most pressure at all three study times were the medial (inner) column of the foot and the forefoot. There was a significant increase in pressure on the midfoot over the course of the training season (from 387.8 to 590 kPa, p = 0.003). The runners who felt the worst cushioning under the midfoot were those who had the highest peak pressures in that area (p = 0.002). The New Balance® 738 running shoe effectively maintains the plantar pressure pattern after 700 km of use under all the zones studied except the midfoot, probably due to material fatigue or deficits of the specific cushioning systems in that area.
... A pesar de que otros estudios investigaron y compararon las repercusiones de correr calzado sobre el tartán y descalzo sobre la hierba (Braunstein, Arampatzis, Eysel, & Brüggemann, 2010), nuestra investigación reproduce una situación más real de competición al tratarse, insistimos, de una superficie homologada y no en laboratorio. ...
... In addition, some studies suggested the peak knee flexion was apparently immediate before ground contact [5]. Additionally, three studies did not discover statistically significant increase in knee flexion [3,15,17]. The unshod running contributed to higher stride frequency compared with shod running. ...
Article
With the increasing popularity of barefoot running, the difference of foot morphology between habitually unshod runners and shod runners is becoming one concern leading to running injuries. The purpose of this study was to analyze the foot skeletal morphological characteristics between habitually unshod runner and shod runner through inverse modelling. A total of eight subjects, including four habitually unshod runners and four habitually shod runners participated in the Computed Tomography (CT) foot scanning test and Mimics was utilized to rebuild foot model and the Inter-Metatarsal Angle (IMA), Metatarsal-Phalangeal Angle (MPA), and Inter-Phalangeal Distance (IPD) were measured to illustrate the morphology difference. The results showed that the Inter-Phalangeal Distance and Inter-Metatarsal Angle of unshod runners were obviously bigger than those of habitually shod feet. And the difference of Inter-Metatarsal Angle between unshod runner and shod runner was also distinct. Not only can this finding be proven of foot morphology variations, but also it can confirm the development of nature foot from unshod running to shod running.
... Alterations in lateral force may lead to the pronation of the foot, and excessive pronation has been related to lower leg and knee pain [39]. The limited studies [40,41] on medial-lateral GRF in barefoot running indicate that there are no differences in peak medial and lateral GRFs between shod and barefoot runners. The findings of our study imply that there is evidence that bionic shoes may reduce the risk of running injuries, as well as protecting the foot during running. ...
Article
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Running-related injuries are common among runners. Recent studies in footwear have shown that designs of shoes can potentially affect sports performance and risk of injury. Bionic shoes combine the functions of barefoot running and foot protection and incorporate traditional unstable structures based on bionic science. The purpose of this study was to investigate ground reaction force (GRF) differences for a 5 km run and how bionic shoes affect GRFs. Sixteen male recreational runners volunteered to participate in this study and finished two 5 km running sessions (a neutral shoe session and a bionic shoe session). Two-way repeated-measures ANOVAs were performed to determine the differences in GRFs. In the analysis of the footwear conditions of runners, bionic shoes showed significant decreases in vertical impulse, peak propulsive force, propulsive impulse, and contact time, while the braking impulse and vertical instantaneous loading rate (VILR) increased significantly compared to the neutral shoes. Main effects for a 5 km run were also observed at vertical GRFs and anterior–posterior GRFs. The increases of peak vertical impact force, vertical average loading rate (VALR), VILR, peak braking force and braking impulse were observed in post-5 km running trials and a reduction in peak propulsive force and propulsive impulse. The interaction effects existed in VILR and contact time. The results suggest that bionic shoes may benefit runners with decreasing injury risk during running. The findings of the present study may help to understand the effects of footwear design during prolonged running, thereby providing valuable information for reducing the risk of running injuries.
... It has been shown that increasing forefoot bending stiffness by running in shoes compared to barefoot Footwear Science (Braunstein, Arampatzis, Eysel, & Br€ uggemann, 2010) and, furthermore, increasing bending stiffness in shoes (Willwacher et al., 2013) shifts the point of application of the ground reaction force anteriorly during push off. The result is an effective lengthening of the ground reaction force lever arm relative to the ankle joint and a change in gearing ratio (Carrier, Heglund, & Earls, 1994) at the ankle joint. ...
Article
Forefoot bending stiffness is a footwear property that has recently been gaining interest despite previously receiving limited attention compared to other footwear characteristics. This review focuses on relevant research studies examining the influence of forefoot bending stiffness on reducing injury and optimizing performance. Discussion of the current limitations and need for future research within the realm of forefoot bending stiffness is also highlighted. By reducing the amount of metatarsophalangeal extension, increased bending stiffness could not only reduce injury risk (e.g. turf-toe), but also serve as a treatment for metatarsal stress fractures by offloading the metatarsals. However, there are surprisingly limited in-depth studies examining how altered forefoot bending stiffness influences injury. Many unknown factors still need to be studied including the appropriate magnitude of bending stiffness and the influence that altering forefoot bending stiffness may have on the injury risk of other joints such as the ankle and knee. Forefoot bending stiffness can influence performance; however, the exact mechanism remains unclear. Early studies focused on foot energetics, while recent studies have shown the importance of altering the movement of the centre of pressure under the foot and the gearing ratio at the ankle joint. There appears to be a specific amount of forefoot bending stiffness for optimal performance. Future research should focus on identifying the exact mechanism of performance improvement with modified bending stiffness to help determine how this optimal stiffness can be identified.
... At the lower speed, in those with an increase in knee angle and reduction in stride length (n = 7), 79% of the variance in knee angle increases was explained by the relative reduction in stride length. Our findings in relation to an increase in knee angle support and extend the findings of De Wit et al. (2000), Lieberman et al. (2010) and Braunstein et al. (2010) in habitually shod recreational runners and those of Bonacci et al. (2013) in well trained runners. The greater variability in hip and knee angle changes between shod and barefoot running at the higher speed may be a factor of the variable efficiency of 800m -5000m runners at the higher speed as discussed above. ...
Article
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Stride length, hip, knee and ankle angles were compared during barefoot and shod running on a treadmill at two speeds. Nine well-trained (1500m time: 3min:59.80s ± 14.7 s) male (22 ±3 years; 73 ±9 kg; 1.79 ±0.4 m) middle distance (800 m – 5,000 m) runners performed 2 minutes of running at 3.05 m/s and 4.72 m/s on an treadmill. This approach allowed continuous measurement of lower extremity kinematic data and calculation of stride length. Statistical analysis using a 2X2 factorial ANOVA revealed speed to have a main effect on stride length and hip angle and footwear to have a main effect on hip angle. There was a significant speed*footwear interaction for knee and ankle angles. Compared to shod running at the lower speed (3.05 m/s), well trained runners have greater hip, knee and ankle angles when running barefoot. Runners undertake a high volume (~75%) of training at lower intensities and therefore knowledge of how barefoot running alters running kinematics at low and high speeds may be useful to the runner.
... At the lower speed, in those with an increase in knee angle and reduction in stride length (n = 7), 79% of the variance in knee angle increases was explained by the relative reduction in stride length. Our findings in relation to an increase in knee angle support and extend the findings of De Wit et al. (2000), Lieberman et al. (2010) and Braunstein et al. (2010in habitually shod recreational runners and those of Bonacci et al. (2013) in well trained runners. The greater variability in hip and knee angle changes between shod and barefoot running at the higher speed may be a factor of the variable efficiency of 800m -5000m runners at the higher speed as discussed above. ...
... This is proposed to be an active adaptation to increase stability in IM. The flatter foot placement in IM during locomotion [Apps et al., 2015] has been related to a reduced ground reaction force moment arm about the ankle [Braunstein et al., 2010]. This would limit the instability effects of IM by keeping the ground reaction force closer to the ankle joint centre, but the current results can not verify the adaptation and warrants further investigation. ...
Article
Unstable shoes (US) continually perturb gait which can train the lower limb musculature, but muscle co-contraction and potential joint stiffness strategies are not well understood. A shoe with a randomly perturbing midsole (IM) may enhance these adaptations. This study compares ankle and knee joint stiffness, and ankle muscle co-contraction during walking and running in US, IM and a control shoe in 18 healthy females. Ground reaction forces, three-dimensional kinematics and electromyography of the gastrocnemius medialis and tibialis anterior were recorded. Stiffness was calculated during loading and propulsion, derived from the sagittal joint angle-moment curves. Ankle co-contraction was analysed during pre-activation and stiffness phases. Ankle stiffness reduced and knee stiffness increased during loading in IM and US whilst walking (ankle, knee: p = .008, .005) and running (p < .001; p = .002). During propulsion, the opposite joint stiffness re-organisation was found in IM whilst walking (both joints p < .001). Ankle co-contraction increased in IM during pre-activation (walking: p = .001; running: p < .001), and loading whilst walking (p = .003), not relating to ankle stiffness. Results identified relative levels of joint stiffness change in unstable shoes, providing new evidence of how stability is maintained at the joint level.
... Il a été démontré que la chaussure avait une influence non négligeable sur la biomécanique des sportifs, en particulier pour les jeunes ayant un squelette encore immature [59][60][61][62]. Au cours des dernières décennies, les chaussures de sport ont beaucoup évolué, intégrant de nouvelles technologies et concepts qui ont pour but de diminuer les forces d'impacts ainsi que de protéger les sportifs grâce à un meilleur amorti et une meilleure stabilisation de l'arrièrepied [63,64]. Cependant, le nombre de blessures du membre inférieur induites par la pratique du sport reste important chaque année et, à notre connaissance, personne n'a clairement prouvé que l'utilisation de chaussures amortissantes permettait de diminuer la gravité des blessures liées à la pratique du sport [65,66]. ...
Article
Objectifs L’objectif de cette revue était d’examiner, chez les enfants, l’influence des chaussures minimalistes sur la biomécanique de course et d’établir une analyse théorique de l’influence de ce type de chaussure sur le risque de blessure. Actualités Entre 8 et 15 ans, les stress répétés induits par la pratique sportive régulière et les poussées de croissance que connaissent les enfants sportifs les rendent enclins aux blessures de sur-sollicitation. Les plus communes pour le membre inférieur sont les maladies d’Osgood-Schlatter et de Sever. Le premier lien entre le corps et le sol étant la chaussure, cette dernière peut être de première importance concernant le risque d’apparition de ces pathologies. Il est suggéré que l’utilisation de chaussures minimalistes modifierait la biomécanique de course et donc potentiellement le risque de blessure. Perspectives et projets De futures investigations sont nécessaires pour identifier, au cours du temps, si les enfants adaptent ou non leur motricité à l’utilisation de chaussures minimalistes et si le port de ces dernières influence le risque de blessure de sur-sollicitation. Conclusion Par rapport aux chaussures conventionnelles, l’utilisation de chaussures minimalistes induit généralement un placement du pied plus à plat avec une cheville plus en flexion plantaire lors de l’impact avec le sol et une flexion du genou moins importante pendant la phase d’appui. Il semble que ces modifications conduisent à une réduction des forces de tension au niveau du genou et qu’elles pourraient diminuer le risque de maladie d’Osgood-Schlatter. Concernant la maladie de Sever, l’analyse biomécanique n’est pas concluante à cause de la complexité de sa patho-mécanique. Le port de chaussures minimalistes devrait diminuer les forces compressives sous le talon par une redistribution de la pression sur l’ensemble de la face plantaire ou sous l’avant-pied mais pourrait en contrepartie augmenter les forces de tension au niveau de l’insertion du tendon d’Achille sur le calcanéum.
... However, the isolated effect of resilience changing in shoe midsole is still unknown in running biomechanics. The majority of biomechanics studies vary the shoe model as a whole to investigate the effects of various structural shoe properties and elements while running (Azevedo et al., 2012;Braunstein et al., 2010;Dixon, 2008;McNair & Marshall, 1994). Such an approach deeply interferes with an appropriate differentiation and interpretation of which shoe characteristics most influence the kinetic and kinematic changes during running. ...
Article
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Background Resilience of midsole material and the upper structure of the shoe are conceptual characteristics that can interfere in running biomechanics patterns. Artificial intelligence techniques can capture features from the entire waveform, adding new perspective for biomechanical analysis. This study tested the influence of shoe midsole resilience and upper structure on running kinematics and kinetics of non-professional runners by using feature selection, information gain, and artificial neural network analysis. Methods Twenty-seven experienced male runners (63 ± 44 km/week run) ran in four-shoe design that combined two resilience-cushioning materials (low and high) and two uppers (minimalist and structured). Kinematic data was acquired by six infrared cameras at 300 Hz, and ground reaction forces were acquired by two force plates at 1,200 Hz. We conducted a Machine Learning analysis to identify features from the complete kinematic and kinetic time series and from 42 discrete variables that had better discriminate the four shoes studied. For that analysis, we built an input data matrix of dimensions 1,080 (10 trials × 4 shoes × 27 subjects) × 1,254 (3 joints × 3 planes of movement × 101 data points + 3 vectors forces × 101 data points + 42 discrete calculated kinetic and kinematic features). Results The applied feature selection by information gain and artificial neural networks successfully differentiated the two resilience materials using 200(16%) biomechanical variables with an accuracy of 84.8% by detecting alterations of running biomechanics, and the two upper structures with an accuracy of 93.9%. Discussion The discrimination of midsole resilience resulted in lower accuracy levels than did the discrimination of the shoe uppers. In both cases, the ground reaction forces were among the 25 most relevant features. The resilience of the cushioning material caused significant effects on initial heel impact, while the effects of different uppers were distributed along the stance phase of running. Biomechanical changes due to shoe midsole resilience seemed to be subject-dependent, while those due to upper structure seemed to be subject-independent.
... In our study, the stance phase was 79.3% of the total time in the shod and 75.4% in the barefoot condition. Previous studies found that immediate transition from shod to barefoot running influences the moment arm of the ground reaction force at the ankle joint resulting in a lower gear ratio (i.e. the ratio between ground reaction force and muscle force moment arms) in the late stance phase [31]. Lower gear ratios at the ankle joint decrease the contact time while running [32], thus providing an explanation for the shorter average per step contact time (7%) we found in the current study during barefoot running. ...
... It is believed that sport shoes can play an essential role in a runner's performance [23] since running efficiency depends on the interaction between the foot and the sport surface. Wearing a running shoe is changing the geometry of the foot-ground interface and the stiffness of the interface due to the deformation of the midsole [24]. Ground reaction forces and kinematic variables vary with shoe hardness and shoe geometry [25]. ...
Article
Energy can be represented in the form of deformation obtained by the applied force. Energy transfer is defined in physics as the energy is moved from one place to another. To make the energy transfer functional, energy should be moved into the right direction. If it is possible to make a better use of the energy in the right direction, the energy efficiency of the structure can be enhanced. This idea leads to the concept of directional energy transfer (DET), which refers to transferring energy from one direction to a specific direction. With the recent development of additive manufacturing and topology optimization, complex structures can be applied to various applications to enhance performances, like a wheel and shoe midsole. While many works are related to structural strength, there is limited research in optimization for energy performance. In this study, a theoretical approach is proposed to measure the directional energy performance of a structure, which can be used to measure the net energy in an intended direction. The purpose is to understand the energy behavior of a structure and to measure if a structure is able to increase energy in the desired direction.
... In previous studies, ankle kinematic and kinetic variables such as plantar flexion [43,44] have been shown to differ between barefoot and shod running gait [43][44][45]. Studies have also reported limited differences between barefoot and shod runners in GRFs [46,47]. ...
Article
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Assessment methods in human locomotion often involve the description of normalised graphical profiles and/or the extraction of discrete variables. Whilst useful, these approaches may not represent the full complexity of gait data. Multivariate statistical methods, such as Principal Component Analysis (PCA) and Discriminant Function Analysis (DFA), have been adopted since they have the potential to overcome these data handling issues. The aim of the current study was to develop and optimise a specific machine learning algorithm for processing human locomotion data. Twenty participants ran at a self-selected speed across a 15m runway in barefoot and shod conditions. Ground reaction forces (BW) and kinematics were measured at 1000 Hz and 100 Hz, respectively from which joint angles (°), joint moments (N.m.kg⁻¹) and joint powers (W.kg⁻¹) for the hip, knee and ankle joints were calculated in all three anatomical planes. Using PCA and DFA, power spectra of the kinematic and kinetic variables were used as a training database for the development of a machine learning algorithm. All possible combinations of 10 out of 20 participants were explored to find the iteration of individuals that would optimise the machine learning algorithm. The results showed that the algorithm was able to successfully predict whether a participant ran shod or barefoot in 93.5% of cases. To the authors’ knowledge, this is the first study to optimise the development of a machine learning algorithm.
... It is hoped that this paper will present important first steps in unifying the process of transitioning to MFW, both for academic and clinical use. Adopt a non-rearfoot strike pattern a "Imagine you are running on sharp, hot stones" [6,15,66,70,72] Increase stride frequency (10%) Use of a metronome [57,73,74] Land more quietly "Imagine running whilst sneaking up on someone" [67] a Note that adopting a non-rearfoot strike can increase ankle work [99][100][101] Received: 15 December 2016 Accepted: 11 August 2017 ...
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Background: Recent interest in barefoot running has led to the development of minimalist running shoes that are popular in distance runners. A careful transition to these shoes has been suggested and examined in the literature. However, no guidelines based on systematic evidence have been presented. The purpose of this review is to systematically examine the methods employed in the literature to transition to minimal footwear (MFW), as well as the outcomes to these studies in distance runners. In addition, MFW transition guidelines for future clinical practice will be presented based on observations from this review. Methods: A systematic database search was employed using PubMed online as the primary database. Twenty papers were included in the final review. Results: All studies implemented a prospective transition design to MFW with a detail of this transition provided, which increased MFW exposure up to an average of 60% (30-100%) at completion. Only 8/20 studies included injury prevention exercises, and 9/20 included gait retraining. The main outcomes of this transition included limited positive evidence of transitioning into MFW for running economy (n = 4 studies) and muscle development (n = 5). The injury incidence comparing running during the MFW transition (17.9 injuries per 100 participants) to matched participants in conventional running shoes (13.4 injuries per 100) appears equivocal (p = 0.219; effect size phi (φ) = 0.06 [very small]). Finally, several important recommendations for clinical practice and future research have been presented. Conclusions: It is hoped that this paper will present important first steps in unifying the process of transitioning to MFW, both for academic and clinical use.
... The most prevalent sites for overuse running injuries occur at the ankle and knee (2,11). Current research primarily focuses on kinetics; however, the kinematic boundaries of the impact force are equally important. ...
Article
The initial contact and midstance angles may influence injury risk. Previous literature has not assessed these angles under the influence of new footwear for a non-exhaustive prolonged run or the relationship between the angles. To assess lower extremity kinematic changes and the relationship between kinematic parameters at initial contact and midstance with prolonged running under the influence of different types of footwear. Twelve experienced, recreational runners (6 male; 6 female; 24.8 ± 8.4 years; 70.5 ± 9.3 kg; 174.1 ± 9.7 cm) ran for 31 minutes at a self-selected pace for three testing sessions wearing maximalist, habitual, and minimalist shoes. Sixteen anatomical retroreflective markers and seven tracking clusters were placed on the participants' lower extremities. Kinematic data were collected every five minutes beginning at minute one. Initial contact angle (IC), maximum angle (MAX) during midstance, and latency (Tmax) between IC and MAX were calculated for the ankle and knee joints in the frontal and sagittal planes. No significant differences were observed between footwear. Rearfoot inversion (F3,33 = 9.72, p < .001) and knee flexion (F6,66 = 5.34, p < .001) at IC increased over time. No significant differences were detected for MAX over time. Tmax for dorsiflexion (F6,66 = 10.26, p < .001), rearfoot eversion, (F6,66 = 7.84, p < .001) and knee flexion (F6,66 = 11.76, p < .001) increased over time. Maximum eversion during midstance is related to the angle at initial contact, and regardless of footwear type, IC and Tmax increased over the duration of the run. No differences in the ankle and knee sagittal or frontal plane kinematics between minimalist, habitual, and maximalist footwear were observed During a self-paced run.
... The barefoot shoe on the other hand has shown the smallest influence, likely because it hardly reduces range of motion and proprioception. Additionally, it has a very thin sole, resulting in the smallest moment arms of vertical and mediolateral ground reaction force 8,49 . It is known that in shod conditions the eversion moment is higher due to a larger moment arm resulting from the increased width of the shoe and the heel flare 50 . ...
Article
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Hip joint loads need careful consideration during postoperative physiotherapy after joint replacement. One factor influencing joint loads is the choice of footwear, but it remains unclear which footwear is favorable. The objective of the present study was to investigate the influence of footwear on hip joint loads in vivo. Instrumented hip endoprostheses were used for in vivo load measurements. The parameters resultant contact force (F res ), bending moment (M bend ) and torsional moment (M tors ) were evaluated during treadmill walking at 4 km/h with different shoe types. In general, footwear tended to increase hip joint loading, with the barefoot shoe having the least influence. F res and M bend were significantly increased during heel strike for all shoe types in comparison to barefoot walking, with everyday shoe (34.6%; p = 0.028 and 47%; p = 0.028, respectively) and men’s shoe (33.2%; p = 0.043 and 41.1%; p = 0.043, respectively) resulting in the highest changes. M tors at AbsMax was increased by all shoes except for the barefoot shoe, with the highest changes for men’s shoe (+ 17.6%, p = 0.043) and the shoe with stiffened sole (+ 17.5%, p = 0.08). Shoes, especially those with stiff soles or elaborate cuishing and guiding elements, increase hip joint loads during walking. The influence on peak loads is higher for M tors than for F res and M bend . For patients in which a reduction of hip joints loads is desired, e.g. during physiotherapy after recent surgery or to alleviate symptoms of osteoarthritis, low profile shoes with a flexible sole may be preferred over shoes with a stiff sole or elaborate cushioning elements.
... Combining these two results, it appears that members of FM pattern group 3, which is characterised by higher FM external rotation amplitudes and consequently higher nonsagittal knee-joint moments compared to the two other FM pattern groups, who suffer from PFPS might benefit from the use of more minimal footwear. This mechanism might help PFPS patients in parallel to the reduced sagittal plane knee-joint moments (Braunstein, Arampatzis, Eysel, & Bruggemann, 2010) and patello-femoral forces (Sinclair, 2014) reported for running barefoot or in minimal footwear. However, higher internal rotation FMs have also been linked to greater non-sagittal plane ankle-joint moments (Willwacher, Goetze et al., 2016). ...
Article
The free moment is considered an important variable during running in lower extremity transverse plane loading of the support leg. The effect of current footwear technology on free moment application has not been widely studied despite evidence that greater free moment amplitudes may be related to common lower extremity overuse injuries. Therefore, the purpose of this study was to determine the effect of current running shoe types on the free moment application in running and to identify which design features specifically influence free moment waveforms. The free moments and lower extremity kinematics of 103 recreational runners were collected when running at 3.5 m/s using force plates embedded in the ground. Six conditions were analysed, ranging from minimalistic to motion-control footwear. Runners were classified into three groups of different free moment pattern using functional principal component and cluster analysis techniques. The results revealed that the free moment application can be affected by footwear technologies used in modern running shoes. Nonetheless, the free moment application was influenced to a greater extent by the overall running technique highlighted by the greater effect sizes for pattern membership compared to footwear effects. Footwear may affect the free moment application as a function of its torsional flexibility and to a lesser extent by means of motion-control features. Future studies should address the effect of footwear design features (such as shoe-mass and traction) on free moment application in greater detail to improve the running style with respect to injury prevention and performance enhancement.
... Nevertheless, despite the nonsignificant vGRF-related results, a forward trunk lean may still be beneficial because the mechanism underlying the reduced knee extensor moment by forward trunk lean is the shortened effective moment arm of GRF to the knee joint (Roberts & Belliveau, 2005). Previous study has shown that the resultant knee joint moment may decrease without significant changes in peak vGRF magnitude (Braunstein, Arampatzis, Eysel, & Brüggemann, 2010). ...
Article
Objectives Previous studies showed that adopting forward trunk lean and forefoot strike patterns may reduce risk of running-related knee injuries. However, the process of learning such forms is unclear. The purpose of the study was to investigate the effects of a 4-week training using simple postural instructions to elicit these changes. Design Longitudinal intervention study. Setting A training included postural instructions: 1) lean your trunk forward, and 2) land on the front part of your feet. Participants Eighteen recreational runners. Main outcome measures Participants were assessed prior to training (PRE), immediately after the instructions (iPST), during training at 2 weeks (2WK) and 4 weeks (4WK), and 7–10 days after the conclusion of training (RET). Assessment consisted of running trials performed at self-selected and controlled speeds, during which the trunk and foot strike angles were assessed. Results Comparing to PRE, forward trunk angle significantly increased by approximately 3.5° and foot strike angle by approximately 7° at 2WK, 4WK and RET. Conclusions A 4-week training with simple postural instructions induced significant changes in trunk and foot strike patterns in recreational runners. Future study is needed to develop clinical therapeutic protocols for runners with and at risk of running-related knee injuries.
... Relative to conventional athletic footwear, minimal footwear tends to be constructed using more flexible materials that are lighter in weight and provide less arch support to replicate the barefoot environment while providing some protection [3]. In general, barefoot and minimal footwear effects have been investigated with respect to movement mechanics and overuse injury risk during running [4][5][6][7][8] and landing [9][10][11][12]. During running, footwear effects may be dependent on lower extremity segment orientations at ground contact [13]. ...
Article
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Effects of barefoot and minimal footwear conditions on performance during jumping (i.e., jump displacement) are unclear with traditional group-level studies because of intra- and interindividual variability. We compared barefoot, minimal, and conventional athletic footwear conditions relative to countermovement vertical jump (CMVJ) performance and muscle activation using a single-subject approach. Fifteen men (1.8 � 0.6 m; 84.5 � 8.5 kg; 23.8 � 2.3 y) performed three CMVJ trials in barefoot, minimal, and conventional footwear conditions while ground reaction forces (GRF) and electromyograms of eight lower extremity muscles were recorded. The Model Statistic procedure (� = 0.05) compared conditions for CMVJ displacement, net impulse, durations of unloading, eccentric, and concentric phases, and average muscle activation amplitudes during the phases. All variables were significantly altered by footwear (p < 0.05) in some participants, but no participant displayed a universal response to all variables with respect to the footwear conditions. Seven of 15 participants displayed different CMVJ displacements among footwear conditions. Additional characteristics should be evaluated to reveal unique individual traits who respond similarly to specific footwear conditions. Considerations for footwear selection when aiming for acute performance enhancement during CMVJ tests should not be determined according to only group analysis results. The current single-subject approach helps to explain why a consensus on the effects of barefoot, minimal, and conventional footwear conditions during the CMVJ remains elusive.
... Several studies also had proved that shoes have strong relationship with health. They may contribute to health injuries or other fatal accidents such as slip and falls during doing activities (Braunstein et al., 2010;Herbaut et al., 2017). Thus, choosing appropriate shoes for any intended purposes is important. ...
Article
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Being difficult to degrade, latex compound waste (LCW) should be handled carefully. In this study the possibility of application of LCW for shoe sole was evaluated. LCW was derived from latex-based industry from local factory. It was blended with natural rubber (NR) with the ratio ranging from 100/0; 90/10; 80/20; 70/30; 60/40 and 50/50. Cure characteristics and mechanical properties including tensile strength, elongation at break, hardness and tear strength, were measured before and after aging. Abrasion loss and slip resistance were also taken account. The results finding showed that crosslink density of the NR/LCW blends were higher than of control. Mechanical properties of the blends were greatly affected by crosslink density. Compared to control, the NR/LCW blends provided lower tensile and elongation, but higher in tear strength, hardness and abrasion loss. Heat aging tended to decrease the mechanical properties. LCW improved the coefficient of friction (CoF).
... In the conservative treatment of tendinopathy, it has been suggested to use heel elevation insoles, which, by raising the heel, presumably reduce the load on the AT [6]. However, scientific works indicate controversial results: raising the heel by 15-18 mm increases [7], decrea ses [8] or does not affect [9,10] the load on the AT during walking. We have not found any work that describes the effectiveness of heel elevation insoles in the treatment of patients with RB or Haglund syndrome. ...
Article
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The aim of this study is the analysis of the equivalent stress on the rear foot structures in retrocalcaneal bursitis, when using heel-elevation insoles of different heights (10 mm and 20 mm). Methods – mathematical calculations of the Achilles force required in the heel-off of the gait stance phase in the conditions of lifting the heel by 10 mm and 20 mm. A 3D-simulation foot model with an enlarged retrocalcaneal bursa was created. The analysis was carried out by the finite element method to calculate and study the stress and strain in the rear foot structures. Results. When using a 10.0 mm height heel-elevation insole, the calf muscle strength, which must be applied to the heel-off of the gait stance phase, was 19.0 % less than without support and 26.8 % less in 20.0 mm insole. Accordingly, analyzing the simulation results in terms of von-Mises stress, the maximum stress observed on the Achilles tendon decreases by 20.0 % and by 30.0 %. The total deformations maximum in the model when using heel-elevation insoles decreased up to 18.1 % and they were localized not in the tendon, but in the bone structures of subtalar joint. The maximum values of the total deformation of the model in the case of 10.0 mm and 20.0 mm heel-elevation insoles were 91.67 mm (–20.2 %) and 80.04 mm (–30.3 %), respectively, compared 114.92 mm in the absence of insoles. When using insole with a height of 10.0 mm, the stress in the retrocalcaneal bursa decreased by 20.0 % and was equal to 14.92 MPa compared to 18.66 MPa, and when using a 20.0 mm insoles - by 30.0 %. Conclusions. It was found that when using 10.0–20.0 mm heel-elevation insoles, the stress distribution in the rear foot structures was significantly reduced by an average of 20.0-30.0 % and correlated with the height of the insoles.
... To date, there has been no experimental evidence on the effects of surface stiffness on multisegment foot mechanics. In addition, prior studies have demonstrated that the adjustment of running mechanics is influenced by the type of running shoes or footwear [15,16]. Therefore, the purpose of the current study is to investigate the effects of surface stiffness on multisegment kinematics of the foot during running with two different types of footwear. ...
Article
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Objective: The aim of this study was to investigate the effects of surface stiffness on multisegment foot kinematics and temporal parameters during running. Methods: Eighteen male subjects ran on three different surfaces (i.e., concrete, artificial grass, and rubber) in both heeled running shoes (HS) and minimal running shoes (MS). Both these shoes had dissimilar sole profiles. The heeled shoes had a higher sole at the heel, a thick base, and arch support, whereas the minimal shoes had a flat base sole. Indeed, the studied biomechanical parameters responded differently in the different footwear during running. Subjects ran in recreational mode speed while 3D foot kinematics (i.e., joint rotation and peak medial longitudinal arch (MLA) angle) were determined using a motion capture system (Qualysis, Gothenburg, Sweden). Information on stance time and plantar fascia strain (PFS) was also collected. Results: Running on different surface stiffness was found to significantly affect the peak MLA angles and stance times for both HS and MS conditions. However, the results showed that the joint rotation angles were not sensitive to surface stiffness. Also, PFS showed no relationship with surface stiffness, as the results were varied as the surface stiffness was changed. Conclusion: The surface stiffness significantly contributed towards the effects of peak MLA angle and stance time. These findings may enhance the understanding of biomechanical responses on various running surfaces stiffness in different shoe conditions.
... This last result could be explained by an asymmetry in the leg function mainly due to an asymmetry in the lever arms of the lower-limb muscles (e.g. Braunstein et al., 2010;Carrier et al., 1994;Maykranz and Seyfarth, 2014). ...
Article
When running, energy is lost during stance to redirect the center of mass of the body (COM) from downwards to upwards. The present study uses a collision-based approach to analyze how these energy losses change with slope and speed. Therefore, we evaluate separately the average collision angle, i.e. the angle of deviation from perpendicular relationship between the force and velocity vectors, during the absorptive and generative part of stance. Our results show that on the level, the collision angle of the absorptive phase is smaller than the collision angle of the generative phase, suggesting that the collision is generative to overcome energy losses by soft tissues. When running uphill, the collision becomes more and more generative as slope increases because the average upward vertical velocity of the COM becomes greater than on the level. When running downhill at a constant speed, the collision angle decreases during the generative phase and increases during the absorptive phase because the average downward vertical velocity of the COM becomes greater. As a result, the difference between the collision angles of the generative and absorptive phases observed on the level disappears on a shallow negative slope of ~-6°, where the collision becomes ’pseudo-elastic’ and collisional energy losses are minimized. At this ’optimal’ slope, the metabolic energy consumption is minimal. On steeper negative slopes, the collision angle during the absorptive phase becomes greater than during the generative phase and the collision is absorptive. At all slopes, the collision becomes more generative when speed increases.
... Previous biomechanical studies have reported that mechanical parameters are affected by factors such as the running technique, running speed, type of running shoes, shoe material, and running surface [6,18,33,35,36]. Mechanical parameters are thought to influence acute and chronic training workloads and provide impor- ...
Article
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The inter-individual variability of running technique is an important factor affecting the negative work of lower extremity joints that leads to muscle damage. Our study examines the relationships between the negative work of the lower extremity joints and the associated mechanical parameters that account for inter-individual variability in the negative work. Twenty-four young male adults were asked to run on a runway at a speed of 3.0 m·s−1. Multiple linear regression analysis was conducted to examine the relationships between the negative work and the associated mechanical parameters for each lower extremity joint. With regards to the results, 76.3% of inter-individual variability in the negative work of the hip joint was accounted for by inter-individual variabilities in the corresponding moment (25.4%) and duration (50.9%). For the knee joint, the inter-individual variabilities in the moment (40.6%), angular velocity (24.5%), and duration (23.8%) accounted for 88.9% of inter-individual variability in the negative work. The inter-individual variability in the moment of the ankle joint alone accounted for 89.3% of the inter-individual variability in the corresponding negative work. These results suggest that runners can change the negative work by adapting their running techniques to influence the relevant mechanical parameter values; however, major parameters corresponding to the change in the negative work are not the same among the lower extremity joints.
... In our study, the stance phase was 79.3% of the total time in the shod and 75.4% in the barefoot condition. Previous studies found that immediate transition from shod to barefoot running influences the moment arm of the ground reaction force at the ankle joint resulting in a lower gear ratio (i.e. the ratio between ground reaction force and muscle force moment arms) in the late stance phase197 . Lower gear ratios at the ankle joint decrease the contact time while running198 , thus providing an explanation for the shorter average per step contact time (7%) ...
Thesis
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Die Bewegungs-kontrollstrategien kontextabhängig und abhängig von unterschiedlichen Kriterien ausgewählt werden. Einerseits ist die Stabilität in den Bewegungszuständen wie der Fortbewegung ausschlaggebend für die ungestörte Ausführung bestimmter Handlungen und erfordert eine effektive Steuerung durch das zentrale Nervensystem. Andererseits wird die Bewegungsstrategieauswahl durch das zentrale Nervensystem dadurch bestimmt, dass die Energiekosten minimiert werden soll. Beide Konzepte (d.h. die Aufrechterhaltung der Stabilität und die Energiekostenminimierung) spielen eine fundamentale Rolle bei der Frage, warum sich Menschen so bewegen, wie sie es tun. Unklar ist dabei allerdings, auf welche Weise das zentrale Nervensystem beide Prinzipien gegeneinander gewichtet. In den letzten 20 Jahren haben uns wissenschaftliche Konzepte wie die Chaostheorie oder die Theorie komplexer Systeme eine neue Herangehensweise an diese Fragen ermöglicht. Diese Arbeit untersucht die dynamische Stabilität menschlicher Fortbewegung mit Hilfe des Konzepts der Ljapunowanalyse. Als erstes wird eine methodologische Untersuchung der Verlässlichkeit des maximalen Ljapunowexponenten beim Gehen und Laufen durchgeführt (Kapitel 2). Danach wird verglichen zwischen dem Laufen unter normalen Umständen und dem darauffolgenden Laufen ohne Schuhe, wobei letzteres eine Abnahme der Stabilität nach dem Übergang zu den neuen Umständen zur Folge hat (Kapitel 3). In der letzten Untersuchung wurde ein unterschiedlich langes Training zur Verbesserung der Laufenergetik durchgeführt, in einer Gruppe nur über einen kurzen und in einer anderen Gruppe über einen etwas längeren Zeitraum (Kapitel 4). Die Ergebnisse zeigen, dass Bewegungskontrollfehler für die Energiekosten beim Laufen eine Rolle spielen können, und legen somit eine flexible Priorisierung der Bewegungskontrolle nahe.
... Previous research has predominantly instructed participants to run at either pre-set (Braunstein, Arampatzis, Eysel, & Brüggemann, 2010;Divert, Mornieux, Baur, Mayer, & Belli, 2005;Squadrone & Gallozzi, 2009;Tscharner, Goepfert, & Nigg, 2003;Williams Iii, Green, & Wurzinger, 2012) or a self-selected running speeds (Bates, Osternig, Mason, & James, 1979;Kurz & Stergiou, 2004;Lieberman et al., 2010;Morley et al., 2010) in order to access differences in running under barefoot and shod running, thereby failing to consider increasing running speed as a potential influencing factor in foot strike pattern adoption. Keller et al. (1996) reported that as running speed increased from 1.0 to 7.0 m/s, the foot strike patterns moved from a RFS to a non-RFS. ...
Article
The majority of barefoot running studies have not considered speed as an influential factor on foot strike pattern. The aim of this study was to investigate differences in foot strike pattern and spatiotemporal characteristics between barefoot and shod overground running at varying speeds. We first determined maximal running speed (Vm) over 50 m in 15 recreationally active men who self-reported as habitual rearfoot strikers. Participants then completed shod and barefoot running trials at different speeds equivalent to approximately 90%, 80%, 70% and 60% of Vm. Sagittal plane two-dimensional (2D) foot-ground contact angle, ankle plantar-dorsi flexion angle, contact time, flight time, step length and step rate variables for each trial were recorded. A significant interaction effect of running speed and footwear condition (p < 0.05) on foot-ground contact angle, ankle plantar-dorsi flexion angle and contact time was observed. There was a main effect of running speed (p < 0.01) on flight time, step length and step rate. There was a main effect of footwear condition on step length (p < 0.01). Participants were more inclined to plantarflex the ankle and contact the ground with the forefoot at higher percentages of Vm, especially when running barefoot.
... Il a été démontré que la chaussure avait une influence non négligeable sur la biomécanique des sportifs, en particulier pour les jeunes ayant un squelette encore immature [59][60][61][62]. Au cours des dernières décennies, les chaussures de sport ont beaucoup évolué, intégrant de nouvelles technologies et concepts qui ont pour but de diminuer les forces d'impacts ainsi que de protéger les sportifs grâce à un meilleur amorti et une meilleure stabilisation de l'arrièrepied [63,64]. Cependant, le nombre de blessures du membre inférieur induites par la pratique du sport reste important chaque année et, à notre connaissance, personne n'a clairement prouvé que l'utilisation de chaussures amortissantes permettait de diminuer la gravité des blessures liées à la pratique du sport [65,66]. ...
... Footwear is identified as a significant extrinsic causal factor of lower leg overuse injuries (Braunstein 2010;Kaufman 2000;Milgrom 2016). 5,10,13 It has been advised to focus on proper fit and comfort (Molloy 2016), but military boot usage may be variable between countries, so insufficiencies in military footwear design leading to overuse injury remain undetermined (Andersen 2016). ...
Preprint
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Load carriage, physical training and sports activities causes 90% of musculoskeletal injuries among military populations, 80% of these injuries are lower leg biomechanical overuse musculoskeletal injuries. Biomechanical overuse musculoskeletal injuries are multi factorial and are defined as cumulative micro-trauma caused by altered load distribution. Feet motion and load distribution during running and marching can be altered with shoes, therefore footwear significantly effects gait and performance of tasks which can lead to injury. So the purpose of this study was to assess the overuse injury prevalence and comfort perception of military boots in Latvian infantry soldiers in order to identify possible risk factor for lower leg overuse injuries.
... Il a été démontré que la chaussure avait une influence non négligeable sur la biomécanique des sportifs, en particulier pour les jeunes ayant un squelette encore immature [59][60][61][62]. Au cours des dernières décennies, les chaussures de sport ont beaucoup évolué, intégrant de nouvelles technologies et concepts qui ont pour but de diminuer les forces d'impacts ainsi que de protéger les sportifs grâce à un meilleur amorti et une meilleure stabilisation de l'arrièrepied [63,64]. Cependant, le nombre de blessures du membre inférieur induites par la pratique du sport reste important chaque année et, à notre connaissance, personne n'a clairement prouvé que l'utilisation de chaussures amortissantes permettait de diminuer la gravité des blessures liées à la pratique du sport [65,66]. ...
Article
Embora o uso de um calçado faça parte do dia a dia da maioria das pessoas, ao avaliar o controle postural na postura em pé, muitos estudos consideram uma condição descalço. Assim, as pessoas diariamente convivem com uma condição onde utilizam calçados, e são avaliadas em uma condição diferente. A justificativa muitas vezes é que o calçado pode influenciar a avaliação. Contudo, pode o calçado habitual de fato influenciar o controle postural estimado pela trajetória do centro de pressão? Para responder a esta pergunta, avaliamos 14 adultos jovens com média de idade de 23 ± (4) anos, estatura de 1,63 ± (0,05) m e massa corporal de 59 ± (7) kg. Eles mantiveram a posição em pé, com apoio bipodal, com e sem usar o seu próprio calçado, com olhos abertos e fechados. Uma plataforma de força foi utilizada para aquisição de forças e momentos de reação do solo. Os dados foram utilizados para o cálculo do centro de pressão. Nenhuma das variáveis do centro de pressão (amplitudes, área e velocidade) diferiu entre as condições calçado e descalço, tanto com olhos abertos quanto fechados. Em resumo, o calçado habitual não influenciou as amplitudes de oscilação do centro de pressão durante a postura em pé.
Chapter
In the last five plus years, many of us have been queried, “What’s the deal with barefoot running?” “Is it good or bad?” or other similar questions. Because of the keen interest and/or curiosity, it is essential that health care providers involved in the care of athletes need to be cognizant of the current trends in the world of training, whether they be long-lasting movements or short-lived fads. It can be expected that our patient athletes will look to us for guidance as to the validity, safety, and effectiveness of such things as barefoot running (BFR), minimalist, and maximalist running. They will have heard all the professed claims and cautions and will look to you to ferret out the truth. Large volumes of research into these activities are unfolding as we speak, and keeping up with current evidence can be cumbersome. Indeed, the amount of new evidence and studies in last 4 years since Jenkins and Cauthon’ s Review of the Literature in the Journal of the American Podiatric Medical Association (JAPMA) has been enormous [1]. Nonetheless, we should endeavor to become equipped to provide our patients with the best opinion one can surmise from current evidence.
Article
Objective: Biomechanical methods were used to explore the influence of age and gender on children’s motor characteristics, and the internal muscle strength were calculated through simulation modeling, so as to provide ideas for the screening of children with diseases and promotion of motor development. Method: BTS motion capture system collects kinematics data; Kistler force platform collects dynamic data, the simulation software(Anybody 5.2)calculates the muscle strength of the lower limb, two-way ANOVA was performed for difference test. Results: gait: SB, SD, SDI and TA muscle strength increased gradually. GMIP muscle strength: 4 years old group is greater than 3-years-old group. SDI and TFL strength: boys’ were greater than girls’. Running: GM muscle strength: boys’ are greater than girls’. PB muscle strength: the 3-year-old group has smallest muscle strength. GMAS muscle strength: the 3-year-old group has the largest muscle strength, boys’ are greater than girls’. Conclusions: (1) Walking: At the striking time, the buffering capacity of ankle is enhanced gradually. At the moment of lifting off the ground, the range of ankle stretching increased gradually, The angular velocity characteristics has a gender difference. The development of hip flexor muscle strength was uneven between boys and girls. The cushioning muscle strength of the ankle was greater in the 5-year-old group.(2) There were gender differences in time parameters of running. The flexion angle of the ankle was larger at the striking time, which was related to different striking patterns. At the time off-the-ground, the 5-year-old group had the largest hip extension angle. Younger children used more frontal plane joint movement and more hip abductor force.
Conference Paper
The current study examined stiffness in the tibialis anterior muscle during the swing phase of walking while wearing various footwear. Seven healthy young men participated in this study. Participants were instructed to walk on a treadmill at 3 km/h while wearing sports shoes, slippers, or slippers with belts. The common peroneal nerve was electrically stimulated every two steps at toe-off during walking. Mechanomyograms (MMGs), electromyograms, and ankle angle were measured. Evoked MMG was extracted using a Kalman filter and subtraction of walking acceleration. The transfer function from the electrical stimulation to the evoked MMG was identified using a singular value decomposition method, and the natural frequency of the transfer function was calculated as an index of muscle stiffness. The natural frequency did not show a clear relationship with footwear type. Four participants showed the lowest natural frequency when they wore slippers with belts. The remaining subjects showed the lowest natural frequency when they wore slippers or shoes. These contrasting findings may have been caused by different degrees of adaptation of participants to the footwear.
Article
Running brings many health benefits, but can lead to injuries to the musculoskeletal system. Modern running shoes have been developed to improve running biomechanics, including the heel-to-toe-drop (HTD) which has been highlighted as a central feature in shoe design. The purpose of this study was to investigate impact force characteristics, joint kinematics and kinetics across three commonly-available HTDs, as well as between running with HTDs and barefoot. Fifteen recreational runners took part in this study. Full-body kinematics and ground reaction force (GRF) data were collected while the participants ran at a speed of 4 m/s in three different shoe conditions (4 mm, 8 mm, and 12 mm HTD) as well as barefoot. Comparisons between the four conditions were made for GRFs, joint kinematics and kinetics of the lower extremities. The results primarily showed that a 4 mm HTD led to increased vertical loading rate and maximum ankle moment and a decreased maximum knee moment compared to 8 mm and 12 mm HTD. In addition, differences in ankle and knee kinematics were seen between running in shoes and running barefoot. A lower HTD mainly altered the kinetics of the ankle and knee. Running with a low HTD did not lead to similar lower limb biomechanics as barefoot running. These findings are important because a deeper understanding of biomechanical responses may lead to more customized footwear, which could decrease the risk of running-related injuries.
Article
This study used transmission-mode ultrasound (US) to evaluate the effect of footwear, with differing heel elevation, on Achilles tendon loading and basic gait parameters. Axial transmission velocity of US was measured in the right Achilles tendon of 20 healthy adults (10 male and 10 female; age: 31 ± 9 years; height: 1.72 ± 0.04 m; weight: 67.8 ± 14.2 kg) while walking barefoot (BF) and in four prototype athletic shoes (S1–S4) on an instrumented treadmill. Shoes were constructed from identical materials and differed only in heel elevation (S1: 0.4 mm; S2: 5 mm, S3: 9.9 mm, S4: 14.8 mm), which was achieved by varying the graded thickness of the midsole beneath the rearfoot. Temporospatial gait parameters, sagittal ankle movement, and vertical ground reaction force were simultaneously recorded at rate of 120 Hz. Shod walking conditions were characterized by a significantly lower cadence, longer stance duration, greater ankle dorsiflexion, larger peak vertical ground reaction force, and higher US transmission velocity in the Achilles tendon than BF walking (P < .05). Incremental heel elevation in footwear resulted in a progressive increase in peak vertical force, a reduction in peak external loading rate, and a small but progressive reduction in US transmission velocity in the Achilles tendon (P < .05). Simple regression modelling predicted that a shoe with 58 mm of heel elevation would effectively replicate values observed during BF walking. Peak US transmission velocity, and hence tensile load, in the Achilles tendon was higher during shod than BF walking and was partially countered by increasing the heel elevation of the shoe. These findings have important clinical implications for the use of footwear in performance applications and in the prevention and rehabilitation of Achilles tendon disorders.
Article
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The purpose of this study was to identify biomechanical and anthropometric variables that contribute to overuse injuries in runner. The comparisons were made between a group of runners who had sustained at least one overuse running injury and a group of runners who had been injury free throughout their running careers. Groups were well matched in important training variables. Synchronized kinetic and rearfoot kinematic variables of both feet were collected by filming subjects running over a force platform at a speed of 4 m.s-1. The injury-free group demonstrated significantly greater posterior thigh (hamstring) flexibility, as measured by a standard sit and reach test. This was the only anthropometric variable in which the groups differed. Within each group, there were no significant differences between left and right foot landing for any biomechanical variable. Biomechanical variables that demonstrated significantly lower values for the injury free group were the vertical force impact peak and the maximal vertical loading rate, with the maximal rate of rearfoot pronation and the touchdown supination angle showing a trend toward being greater in the injury free group. These results suggest that runners who have developed stride patterns that incorporate relatively low levels of impact forces, and a moderately rapid rate of pronation are at a reduced risk of incurring overuse running injuries. (HERACLES) Identification des variables biomecaniques et anthropometriques intervenant dans l'etiologie des lesions de fatigue des membres inferieurs chez les coureurs de fond.
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The in Vivo pathomechanics of osteoarthritis (OA) at the knee is described in a framework that is based on an analysis of studies describing assays of biomarkers, cartilage morphology, and human function (gait analysis). The framework is divided into an Initiation Phase and a Progression Phase. The Initiation Phase is associated with kinematic changes that shift load bearing to infrequently loaded regions of the cartilage that cannot accommodate the loads. The Progression Phase is defined following cartilage breakdown. During the Progression Phase, the disease progresses more rapidly with increased load. While this framework was developed from an analysis of in Vivopathomechanics, it also explains how the convergence of biological, morphological, and neuromuscular changes to the musculoskeletal system during aging or during menopause lead to the increased rate of idiopathic OA with aging. Understanding the in Vivo response of articular cartilage to its physical environment requires an integrated view of the problem that considers functional, anatomical, and biological interactions. The integrated in Vivoframework presented here will be helpful for the interpretation of laboratory experiments as well as for the development of new methods for the evaluation of OA at the knee.
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Experiments were conducted on normal level gait to determine the synergistic patterns present in the forces causing joint moments and those associated with the generation, absorption and transfer of mechanical energy. The following generalizations can be made about the patterns: (i) During swing phase three forces (gravitational, muscle and knee joint acceleration) are responsible for shank rotation, and are shown to act together during both acceleration and deceleration.—(ii) The patterns of generation, absorption and transfer of mechanical energy at the joints are detailed. These patterns demonstrate inter-segment transfers of energy through the joint centres, and through the muscles, as well as the more recognized generation and absorption by the muscles themselves.—As a result of the complexity shown in these patterns it is cautioned that fundamental relationships that may have been derived from controlled biomechanical experiments (such as horizontal flexion and extension of the forearm) are not likely to apply to more normal movements such as gait.
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The equations of motion are formulated for a set of interacting rigid bodies. An explicit formulation could be derived for the total moment of the forces on such a system. This is applied to (1) the intersegmental moment in a multisegment rigid-body model, and (2) the interpretation of the 'centre of pressure' as defined in the studies of human posture.
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The scaling of bone and muscle geometry in mammals suggests that peak stresses (ratio of force to cross-sectional area) acting in these two support elements increase with increasing body size. Observations of stresses acting in the limb bones of different sized mammals during strenuous activity, however, indicate that peak bone stress is independent of size (maintaining a safety factor of between 2 and 4). It appears that similar peak bone stresses and muscle stresses in large and small mammals are achieved primarily by a size-dependent change in locomotor limb posture: small animals run with crouched postures, whereas larger species run more upright. By adopting an upright posture, large animals align their limbs more closely with the ground reaction force, substantially reducing the forces that their muscles must exert (proportional to body mass) and hence, the forces that their bones must resist, to counteract joint moments. This change in limb posture to maintain locomotor stresses within safe limits, however, likely limits the maneuverability and accelerative capability of large animals.
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The characteristics of the midsole were examined in four pairs of running shoes by a materials test. The variables of interest were the peak acceleration, time to peak acceleration and the kinetic energy absorbed. Ten subjects then ran at a recreational jogging pace (3.5 ms-1) barefoot and in the shoes. An accelerometer secured to the lower tibia was used to measure the peak acceleration and time to peak acceleration associated with footstrike. Subjects were also videoed and a kinematic analysis was undertaken at the knee and ankle joints. The results from the materials test showed that the shoes differed in their midsole characteristics, however, no significant differences (P > 0.05) were observed in the peak acceleration and time to peak acceleration during running in shoes. These variables were significantly greater in the barefoot running condition (P < 0.05), as compared with running in shoes. Small and subtle kinematic differences were observed between the barefoot and shoe conditions. It appears that the differences observed between the shoes in the materials test were not sufficient to elicit the kinematic changes observed between the barefoot and shoe conditions. It is suggested that runners operate within a 'kinetic bandwidth' when responding to impact stresses.
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Human feet and toes provide a mechanism for changing the gear ratio of the ankle extensor muscles during a running step. A variable gear ratio could enhance muscle performance during constant-speed running by applying a more effective prestretch during landing, while maintaining the muscles near the high-efficiency or high-power portion of the force-velocity curve during takeoff. Furthermore, during acceleration, variable gearing may allow muscle contractile properties to remain optimized despite rapid changes in running speed. Forceplate and kinematic analyses of running steps show low gear ratios at touchdown that increase throughout the contact phase.
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A running animal coordinates the actions of many muscles, tendons, and ligaments in its leg so that the overall leg behaves like a single mechanical spring during ground contact. Experimental observations have revealed that an animal's leg stiffness is independent of both speed and gravity level, suggesting that it is dictated by inherent musculoskeletal properties. However, if leg stiffness was invariant, the biomechanics of running (e.g. peak ground reaction force and ground contact time) would change when an animal encountered different surfaces in the natural world. We found that human runners adjust their leg stiffness to accommodate changes in surface stiffness, allowing them to maintain similar running mechanics on different surfaces. These results provide important insight into mechanics and control of animal locomotion and suggest that incorporating an adjustable leg stiffness in the design of hopping and running robots is important if they are to match the agility and speed of animals on varied terrain.
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At self-selected walking speeds, elderly compared with young adults generate decreased joint torques and powers in the lower extremity. These differences may be actual gait-limiting factors and neuromuscular adaptations with age or simply a consciously selected motor pattern to produce a slower gait. The purpose of the study was to compare joint torques and powers of young and elderly adults walking at the same speed. Twelve elderly and fourteen young adults (ages 69 and 21 yr) walked at 1.48 m/s over a force platform while being videotaped. Hip, knee, and ankle torques and powers were calculated from the reaction force and kinematic data. A support torque was calculated as the sum of the three joint torques. Extensor angular impulse during stance and positive work at each joint were derived from the torques and powers. Step length was 4% shorter and cadence was 4% higher in elderly adults (both P < 0.05) compared with young adults. Support angular impulse was nearly identical between groups, but elderly adults had 58% greater angular impulse and 279% more work at the hip, 50% less angular impulse and 39% less work at the knee, and 23% less angular impulse and 29% less work at the ankle compared with young adults (t-test, all P < 0.05). Age caused a redistribution of joint torques and powers, with the elderly using their hip extensors more and their knee extensors and ankle plantar flexors less than young adults when walking at the same speed. Along with a reduction in motor and sensory functions, the natural history of aging causes a shift in the locus of function in motor performance.
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Mammals use the elastic components in their legs (principally tendons, ligaments, and muscles) to run economically, while maintaining consistent support mechanics across various surfaces. To examine how leg stiffness and metabolic cost are affected by changes in substrate stiffness, we built experimental platforms with adjustable stiffness to fit on a force-plate-fitted treadmill. Eight male subjects [mean body mass: 74.4 +/- 7.1 (SD) kg; leg length: 0.96 +/- 0.05 m] ran at 3.7 m/s over five different surface stiffnesses (75.4, 97.5, 216.8, 454.2, and 945.7 kN/m). Metabolic, ground-reaction force, and kinematic data were collected. The 12.5-fold decrease in surface stiffness resulted in a 12% decrease in the runner's metabolic rate and a 29% increase in their leg stiffness. The runner's support mechanics remained essentially unchanged. These results indicate that surface stiffness affects running economy without affecting running support mechanics. We postulate that an increased energy rebound from the compliant surfaces studied contributes to the enhanced running economy.
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To provide an extensive and up to date database for specific running related injuries, across the sexes, as seen at a primary care sports medicine facility, and to assess the relative risk for individual injuries based on investigation of selected risk factors. Patient data were recorded by doctors at the Allan McGavin Sports Medicine Centre over a two year period. They included assessment of anthropometric, training, and biomechanical information. A model was constructed (with odds ratios and their 95% confidence intervals) of possible contributing factors using a dependent variable of runners with a specific injury and comparing them with a control group of runners who experienced a different injury. Variables included in the model were: height, weight, body mass index, age, activity history, weekly activity, history of injury, and calibre of runner. Most of the study group were women (54%). Some injuries occurred with a significantly higher frequency in one sex. Being less than 34 years old was reported as a risk factor across the sexes for patellofemoral pain syndrome, and in men for iliotibial band friction syndrome, patellar tendinopathy, and tibial stress syndrome. Being active for less than 8.5 years was positively associated with injury in both sexes for tibial stress syndrome; and women with a body mass index less than 21 kg/m(2) were at a significantly higher risk for tibial stress fractures and spinal injuries. Patellofemoral pain syndrome was the most common injury, followed by iliotibial band friction syndrome, plantar fasciitis, meniscal injuries of the knee, and tibial stress syndrome. Although various risk factors were shown to be positively associated with a risk for, or protection from, specific injuries, future research should include a non-injured control group and a more precise measure of weekly running distance and running experience to validate these results.
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Patellofemoral pain syndrome (PFPS) is a common knee problem with a diverse aetiology. One of the clinically well accepted risk factors is malalignment of the lower extremities, including excessive foot pronation, tibial and femoral rotations. A feature of footwear technology entitled 'motion control' aims to reduce excessive movements of the rearfoot during sports activities, and has been developed and used by runners. However, no studies have reported a causal relationship between footwear and PFPS. This review attempts to explore a possible link between the footwear and PFPS so as to shed light on whether proper selection of shoes may be an adjunct therapeutic consideration in the management of patients with PFPS.
Article
Running is one of the most popular leisure sports activities. Next to its beneficial health effects, negative side effects in terms of sports injuries should also be recognised. Given the limitations of the studies it appears that for the average recreational runner, who is steadily training and who participates in a long distance run every now and then, the overall yearly incidence rate for running injuries varies between 37 and 56%. Depending on the specificity of the group of runners concerned (competitive athletes; average recreational joggers; boys and girls) and on different circumstances these rates vary. If incidence is calculated according to exposure of running time the incidence reported in the literature varies from 2.5 to 12.1 injuries per 1000 hours of running. Most running injuries are lower extremity injuries, with a predominance for the knee. About 50 to 75% of all running injuries appear to be overuse injuries due to the constant repetition of the same movement. Recurrence of running injuries is reported in 20 to 70% of the cases. From the epidemiological studies it can be concluded that running injuries lead to a reduction of training or training cessation in about 30 to 90% of all injuries, about 20 to 70% of all injuries lead to medical consultation or medical treatment and 0 to 5% result in absence from work. Aetiological factors associated with running injuries include previous injury, lack of running experience, running to compete and excessive weekly running distance. The association between running injuries and factors such as warm-up and stretching exercises, body height, malalignment, muscular imbalance, restricted range of motion, running frequency, level of performance, stability of running pattern, shoes and inshoe orthoses and running on 1 side of the road remains unclear or is backed by contradicting or scarce research findings. Significantly not associated with running injuries seem age, gender, body mass index, running hills, running on hard surfaces, participation in other sports, time of the year and time of the day. The prevention of sports injuries should focus on changes of behaviour by health education. Health education on running injuries should primarily focus on the importance of complete rehabilitation and the early recognition of symptoms of overuse, and on the provision of training guidelines.
Article
The reproducibility of quantitative gait analysis measurements is an important consideration when analyzing data of both normal subjects and patients. Waveform similarity statistics were used to assess the reproducibility of lower extremity kinematic and kinetic data collected on 5 normal adult subjects. For each subject, gait evaluations were done on 3 separate test days with 3 trials collected each day. Pelvis angles were fairly repeatable, however, with notably poor reproducibility in sagittal plane tilt. Re-application errors of the sacral wand coupled with a small range of motion are believed to be the principle contributors to variability in this pelvis angle. The sagittal plane angles for the hip, knee, and ankle demonstrated excellent repeatability within test days and between test days. Frontal and transverse plane angles were fairly repeatable within test days but between-day repeatability was considerably lower. The 'downstream' errors accompanying Euler angle calculations coupled with the smaller ranges of motion in the non-sagittal plane angles are suggested to contribute to the ambient variability already in these data and, thus, affect the within-day repeatability. Errors in re-application of midthigh and midcalf wands further contribute to the variability of these data between test days, Net resultant joint forces and moments were repeatable overall with slightly lower between-day statistical values. The exception to this observation was the adduction moment of the ankle which was notably variable between test days. Several explanations for this variability are presented. Results of this study have led to modifications in some marker placement procedures and reinforced the need for others already being used.
Article
: The modern running shoe typically features a large cushioned heel intended to dissipate the energy at heel strike to the knees and hips. The purpose of this study was to evaluate the effect that shoes have upon the running biomechanics among competitive adolescent runners. We wish to answer the question of whether running style is altered in these athletes because of footwear. : Twelve competitive adolescent athletes were recruited from local track teams. Each ran on a treadmill in large heel trainers, track flats, and barefoot. Four different speeds were used to test each athlete. The biomechanics were assessed with a motion capture system. Stride length, heel height during posterior swing phase, and foot/ground contact were recorded. : Shoe type markedly altered the running biomechanics. The foot/ground contact point showed differences in terms of footwear (P<0.0001) and speed (P=0.000215). When wearing trainers, the athletes landed on their heels 69.79% of the time at all speeds (P<0.001). The heel was the first point of contact <35% of the time in the flat condition and <30% in the barefoot condition. : Running biomechanics are significantly altered by shoe type in competitive adolescents. Heavily heeled cushioned trainers promote a heel strike pattern, whereas track flats and barefoot promote a forefoot or midfoot strike pattern. Training in heavily cushioned trainers by the competitive runner has not been clearly shown to be detrimental to performance, but it does change the gait pattern. It is not known whether the altered biomechanics of the heavily heeled cushioned trainer may be detrimental to the adolescent runner who is still developing a running style.
Article
The pectoral girdle and fore limb of Equus and Dasypus are compared. It is shown that the shoulder muscles of the horse have a small mechanical advantage (1/13 for the m. teres major) and are therefore adapted to produce rapid movements of the limb; these muscles in the armadillo have a larger mechanical advantage (1/4 for the m. teres) to produce slower movements, while exerting a greater force. The broad scapulae and short legs of fossorial mammals are adaptations producing powerful movements of the foot, usually with strong abductor action. Aquatic mammals show similar modifications, though without the emphasis on abductor movements. The high, narrow scapulae and long legs of cursorial mammals are explained as adaptations to speed, though the detailed arrangements by which this is achieved differ in cursorial ungulates and carnivores. The sharp angles at the ends of the vertebral border of the scapula in cursorial ungulates provide pints of insertion for two parts of the m. serratus, which act as antagonists in the fore-and-aft movement of the shoulder. Similarly in the dog, and probably all cursorial carnivores and lagomorphs, the sharp vertebro-axillary angle affords a point of insertion for the posterior digitations of the m. serratus. The mechanical adaptations of the olecranon process and the m. triceps are described. The structure of the vertebral column and axial musculature is shown to depend upon gait. Two types of gallop, the horse gallop and leaping gallop (e.g. dog) are analysed and the association between gait and structure described. The mechanics of gaits are discussed in an appendix. The extensor muscles from the pelvis to the femur fall into two groups, an iliac group adapted to rapid extension of the thigh, and an ischio-pubic group adapted to slower but more powerful thigh extension. The relative proportions of the two regions of the pelvis vary according to the gaits adopted. In cursorial ungulates the ilium is long and the ischio-pubic region short, whereas in aquatic mammals the latter region predominates. The lengths and cross-sectional areas of the bones of the hind limb are shown to be correlated with gait in aquatic, cursorial (leaping gallop and horse gallop), saltatorial and graviportal mammals.
Article
No Abstract. Peer Reviewed http://deepblue.lib.umich.edu/bitstream/2027.42/37467/1/1330170405_ftp.pdf
Article
Based on the spline software of Lyche et al., a subroutine package is presented in which the amount of smoothing on a set of n noisy datapoints is determined from the data by means of the Generalized Cross-Validation (GCV) or predicted Mean-Squared Error (MSE) criteria of Wahba and her collaborators. Following an idea of Hutchinson and de Hoog, an efficient O (m2n) algorithm is used for calculating the criterion functions, where 2m is the order of the spline function. In this fashion, earlier O (n3) approaches based on the singular value decomposition can be avoided.
Article
To determine the effect of modern-day running shoes on lower extremity joint torques during running. Two-condition experimental comparison. A 3-dimensional motion analysis laboratory. A total of 68 healthy young adult runners (37 women) who typically run in running shoes. All subjects ran barefoot and in the same type of stability running footwear at a controlled running speed. Three-dimensional motion capture data were collected in synchrony with ground reaction force data from an instrumented treadmill for each of the 2 conditions. Peak 3-dimensional external joint torques at the hip, knee, and ankle as calculated through a full inverse dynamic model. Increased joint torques at the hip, knee, and ankle were observed with running shoes compared with running barefoot. Disproportionately large increases were observed in the hip internal rotation torque and in the knee flexion and knee varus torques. An average 54% increase in the hip internal rotation torque, a 36% increase in knee flexion torque, and a 38% increase in knee varus torque were measured when running in running shoes compared with barefoot. The findings at the knee suggest relatively greater pressures at anatomical sites that are typically more prone to knee osteoarthritis, the medial and patellofemoral compartments. It is important to note the limitations of these findings and of current 3-dimensional gait analysis in general, that only resultant joint torques were assessed. It is unknown to what extent actual joint contact forces could be affected by compliance that a shoe might provide, a potentially valuable design characteristic that may offset the observed increases in joint torques.
Article
A suggested link between ambulatory mechanics and injury development has resulted in significant interest the development of footwear to change locomotion patterns. The purpose of this study was to test the hypothesis that there will be significant changes in the kinematics and kinetics at the ankle and minimal changes at the knee and hip in the mechanics of running in a shoe with a sagittal plane curvature relative to a flat soled shoe. During running 3-D lower extremity kinematics and kinetics for 19 healthy volunteers were quantified using an optoelectronics system and a force plate. Data were collected for a flat sole conventional shoe (New Balance 658 (Control)) and a shoe with a rounded sole in the sagittal plane (Masai Barefoot Technologies (MBT)). Data were compared for the two shoe conditions using paired Student t-tests (alpha=0.05). The ankle dorsi-flexion angles at heel-strike and mid-stance were greater, while the ankle plantar and dorsi-flexion moments and peak ankle joint power were significantly lower with the MBT relative to the control (P<0.05). Decreases in the first medial GRF peak and the peak anterior GRF peak were also found for running in the MBT shoe. Despite a major difference in sole geometry, accommodations to the rockered sole were found only at the ankle. These results suggest changes in ankle kinematics and kinetics may be used to minimize the effect of changes in sole rocker on limb dynamics. Thus, changes in shoe rocker may offer potential therapeutic opportunities for running related conditions at the ankle without substantial risk to the knee or hip.
Article
A model of running is proposed in which the leg is represented as a rack-and-pinion element in series with a damped spring. The rack-and-pinion element emphasizes the role of descending commands, while the damped spring represents the dynamic properties of muscles and the position and the rate sensitivity of reflexes. This model is used to predict separately the effect of track compliance on step length and ground contact time. The predictions are compared with experiments in which athletes ran over tracks of controlled spring stiffness. A sharp spike in foot force up to 5 times body weight was found on hard surfaces, but this spike disappeared as the athletes ran on soft experimental tracks. Both ground contact time and step length increased on very compliant surfaces, leading to moderately reduced running speeds, but a range of track stiffness was discovered which actually enhances speed.
Article
Running is one of the most popular leisure sports activities. Next to its beneficial health effects, negative side effects in terms of sports injuries should also be recognised. Given the limitations of the studies it appears that for the average recreational runner, who is steadily training and who participates in a long distance run every now and then, the overall yearly incidence rate for running injuries varies between 37 and 56%. Depending on the specificity of the group of runners concerned (competitive athletes; average recreational joggers; boys and girls) and on different circumstances these rates vary. If incidence is calculated according to exposure of running time the incidence reported in the literature varies from 2.5 to 12.1 injuries per 1000 hours of running. Most running injuries are lower extremity injuries, with a predominance for the knee. About 50 to 75% of all running injuries appear to be overuse injuries due to the constant repetition of the same movement. Recurrence of running injuries is reported in 20 to 70% of the cases. From the epidemiological studies it can be concluded that running injuries lead to a reduction of training or training cessation in about 30 to 90% of all injuries, about 20 to 70% of all injuries lead to medical consultation or medical treatment and 0 to 5% result in absence from work. Aetiological factors associated with running injuries include previous injury, lack of running experience, running to compete and excessive weekly running distance. The association between running injuries and factors such as warm-up and stretching exercises, body height, malalignment, muscular imbalance, restricted range of motion, running frequency, level of performance, stability of running pattern, shoes and inshoe orthoses and running on 1 side of the road remains unclear or is backed by contradicting or scarce research findings. Significantly not associated with running injuries seem age, gender, body mass index, running hills, running on hard surfaces, participation in other sports, time of the year and time of the day. The prevention of sports injuries should focus on changes of behaviour by health education. Health education on running injuries should primarily focus on the importance of complete rehabilitation and the early recognition of symptoms of overuse, and on the provision of training guidelines.
Article
The purpose of this investigation was to study the influence of the flare at the lateral side of the heel of running shoes on: initial and total pronation; impact forces in heel-toe running; and to explain the results with a mechanical model. The experimental part of the study was performed by using 14 male runners. Their running movement (4 m/s) was quantified by using a force platform and high-speed film (100 frames X s-1). Three shoes were used, identical except in their lateral heel flare, one shoe with a conventional flare of 16 degrees, a second shoe with no flare, and a third shoe with a rounded heel (negative flare). The experimental results indicate that (for the used set of shoes); increasing heel flare increases the amount of initial pronation; changes in heel flare do not affect the magnitude of the total pronation; and changes in heel flare do not alter the magnitude of the impact force peaks. Since shoes with rounded lateral heels do reduce initial pronation, it is speculated that this construction could be used to prevent anterior medial compartment syndrome at the tibia of runners. It was concluded that more research is needed to specify whether the reported result is representative for various shoe types or is shoe specific.
Article
An important determinant of the mechanics of running is the effective vertical stiffness of the body. This stiffness increases with running speed. At any one speed, the stiffness may be reduced in a controlled fashion by running with the knees bent more than usual. In a series of experiments, subjects ran in both normal and flexed postures on a treadmill. In other experiments, they ran down a runway and over a force platform. Results show that running with the knees bent reduces the effective vertical stiffness and diminishes the transmission of mechanical shock from the foot to the skull but requires an increase of as much as 50% in the rate of O2 consumption. A new dimensionless parameter (u omega 0/g) is introduced to distinguish between hard and soft running modes. Here, omega 0 is the natural frequency of a mass-spring system representing the body, g is gravity, and u is the vertical landing velocity. In normal running, this parameter is near unity, but in deep-flexed running, where the aerial phase of the stride cycle almost disappears, u omega 0/g approaches zero.
Article
The purpose of this study was to investigate the influence of midsole hardness and running velocity on external impact forces in heel-toe running. Fourteen subjects were assessed with a force platform and high speed film while running at speeds of 3, 4, 5 and 6 m s-1. The result showed that running velocity does influence external impact force peaks (linear connection) and that midsole hardness does not influence magnitude and loading rate of the external vertical impact forces. Changes in kinematic and kinetic data can be used to explain this result mechanically. However, the neuromuscular control mechanisms to keep external impact forces constant are not known.
Article
As the number of runners has increased dramatically, so has the incidence of running-related injuries. In order to determine what training factors are associated with running-related injuries, as well as what percentage of injured runners seeks professional medical attention, a random sample of entrants to a 10 kilometer race was asked to complete a questionnaire. There were 451 respondents, 355 men and 96 women, with a nonresponse rate of 12.7%. Nonrespondents did not differ from respondents with regard to age or sex. Forty-seven percent of respondents indicated that they had sustained a running-related injury in the last 2 years. Injured runners differed significantly from noninjured runners in that they were more likely to have run more miles per week, run more days per week, run a faster pace, run more races in the last year, stretched before running, and not participated regularly in other sports. Associated with injury, but not statistically significant, were those who had run marathons and had done muscle-strengthening exercises. No association was found with regard to the length of time running, running surfaces, part of the foot first contacting the ground, or running intervals, sprints, or hills. Seventy percent of those injured sought professional medical care, with 76% of these having a good or excellent recovery from their injuries. Compliance with medical advice correlated well with treatment success.