Regulation of foot and ankle quasi-stiffness during human hopping across a range of frequencies

Kessler, Sarah; Lichtwark, Glen A.; Welte, Lauren; Rainbow, Michael J.; Kelly, Luke A.

doi:10.1016/j.jbiomech.2020.109853

Cited by 21 publications

(23 citation statements)

References 40 publications

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“…In addition, some recent studies (e.g. Kessler et al 2020) have reported that using a rigid-body foot model (as done in this study) could lead to an overestimation of ankle joint power, thus affecting Achilles tendon mechanical work estimates. One other limitation is the estimation of GM forces based on reported values of relative PCSA, assuming consistent force contribution at all running speeds and a negligible inter-muscular force transmission between the individual plantar flexor muscles.…”

Section: Methodological Limitations and Considerationsmentioning

confidence: 76%

The influence of Achilles tendon mechanical behaviour on “apparent” efficiency during running at different speeds

et al. 2020

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Purpose We investigated the role of elastic strain energy on the “apparent” efficiency of locomotion (AE), a parameter that is known to increase as a function of running speed (up to 0.5–0.7) well above the values of “pure” muscle efficiency (about 0.25–0.30). Methods In vivo ultrasound measurements of the gastrocnemius medialis (GM) muscle–tendon unit (MTU) were combined with kinematic, kinetic and metabolic measurements to investigate the possible influence of the Achilles tendon mechanical behaviour on the mechanics (total mechanical work, WTOT) and energetics (net energy cost, Cnet) of running at different speeds (10, 13 and 16 km h−1); AE was calculated as WTOT/Cnet. Results GM fascicles shortened during the entire stance phase, the more so the higher the speed, but the majority of the MTU displacement was accommodated by the Achilles tendon. Tendon strain and recoil increased as a function of running speed (P < 0.01 and P < 0.001, respectively). The contribution of elastic energy to the positive work generated by the MTU also increased with speed (from 0.09 to 0.16 J kg−1 m−1). Significant negative correlations (P < 0.01) were observed between tendon work and metabolic energy at each running speed (the higher the tendon work the lower the metabolic demand) and significant positive correlations were observed between tendon work and AE (P < 0.001) at each running speed (the higher the tendon work the higher the efficiency). Conclusion These results support the notion that the dynamic function of tendons is integral in reducing energy expenditure and increasing the “apparent” efficiency of running.

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Section: Methodological Limitations and Considerationsmentioning

confidence: 76%

The influence of Achilles tendon mechanical behaviour on “apparent” efficiency during running at different speeds

et al. 2020

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“…However, there is substantial motion that occurs in the arch during this phase, which conflicts with the description of the foot as a rigid lever, as has been recently questioned by several researchers [14,25]. While this study lacks kinetic data to measure dynamic stiffness of the arch, previous studies have shown that the windlass mechanism does not stiffen the foot [26][27][28], and that the arch is more compliant in late stance than in the first half of stance [14]. Therefore, we propose that the arch complex is best described as a dynamic lever rather than a rigid lever, as it provides a stable base of support for push-off, with a constantly changing lever arm.…”

Section: Discussionmentioning

confidence: 82%

The extensibility of the plantar fascia influences the windlass mechanism during human running

et al. 2021

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The arch of the human foot is unique among hominins as it is compliant at ground contact but sufficiently stiff to enable push-off. These behaviours are partly facilitated by the ligamentous plantar fascia whose role is central to two mechanisms. The ideal windlass mechanism assumes that the plantar fascia has a nearly constant length to directly couple toe dorsiflexion with a change in arch shape. However, the plantar fascia also stretches and then shortens throughout gait as the arch-spring stores and releases elastic energy. We aimed to understand how the extensible plantar fascia could behave as an ideal windlass when it has been shown to strain throughout gait, potentially compromising the one-to-one coupling between toe arc length and arch length. We measured foot bone motion and plantar fascia elongation using high-speed X-ray during running. We discovered that toe plantarflexion delays plantar fascia stretching at foot strike, which probably modifies the distribution of the load through other arch tissues. Through a pure windlass effect in propulsion, a quasi-isometric plantar fascia's shortening is delayed to later in stance. The plantar fascia then shortens concurrently to the windlass mechanism, likely enhancing arch recoil at push-off.

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“…Recently, multi-segment kinetic foot models have received increasing attention in methodological and clinical studies, providing new insights into the individual power distributions of the intrinsic foot joints [10][11][12]. These kinetic foot models further highlighted the shortcomings of computing ankle joint moments and power with a one-segment foot modeling approach, as it overestimates ankle joint power [12][13][14]. These shortcomings may further lead to clinical misinterpretation of how a therapeutic intervention benefits or degrades biomechanical performance, as the estimated changes simply reflect methodological errors inherent to conventionally modeling the foot as a single segment [12,15].…”

Section: Introductionmentioning

confidence: 99%

Impact of foot modeling on the quantification of the effect of total ankle replacement: A pilot study

et al. 2021

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Regulation of foot and ankle quasi-stiffness during human hopping across a range of frequencies

Cited by 21 publications

References 40 publications

The influence of Achilles tendon mechanical behaviour on “apparent” efficiency during running at different speeds

The influence of Achilles tendon mechanical behaviour on “apparent” efficiency during running at different speeds

The extensibility of the plantar fascia influences the windlass mechanism during human running

Impact of foot modeling on the quantification of the effect of total ankle replacement: A pilot study

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