Running in the real world: adjusting leg stiffness for different surfaces

Ferris, Daniel P.; Louie, Micky; Farley, Claire T.

doi:10.1098/rspb.1998.0388

Cited by 491 publications

(440 citation statements)

References 27 publications

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“…This can be related to a more pronounced heel strike and corresponds with the findings of De Wit, De Clercq, and Aerts (2000) who studied heel strike during running. On the one hand ankle kinematics shows adjustments in foot strike on different substrates (as in running, Ferris, Louie, & Farley, 1998). We also note that the natural soil our subjects walked on is hard and comparable to a layer of buffalo leather (for details see (Nagel, Fernholz, Kibele, & Rosenbaum, 2008)).…”

Section: Discussionmentioning

confidence: 99%

Biomechanical implications of walking with indigenous footwear

Willems¹,

Stassijns

Cornelis

et al. 2017

American J Phys Anthropol

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ObjectivesThis study investigates biomechanical implications of walking with indigenous “Kolhapuri” footwear compared to barefoot walking among a population of South Indians.Materials and methodsTen healthy adults from South India walked barefoot and indigenously shod at voluntary speed on an artificial substrate. The experiment was repeated outside, on a natural substrate. Data were collected from (1) a heel‐mounted 3D‐accelerometer recording peak impact at heel contact, (2) an ankle‐mounted 3D‐goniometer (plantar/dorsiflexion and inversion/eversion), and (3) sEMG electrodes at the m. tibialis anterior and the m. gastrocnemius medialis.ResultsData show that the effect of indigenous footwear on the measured variables, compared to barefoot walking, is relatively small and consistent between substrates (even though subjects walked faster on the natural substrate). Walking barefoot, compared to shod walking yields higher impact accelerations, but the differences are small and only significant for the artificial substrate. The main rotations of the ankle joint are mostly similar between conditions. Only the shod condition shows a faster ankle rotation over the rapid eversion motion on the natural substrate. Maximal dorsiflexion in late stance differs between the footwear conditions on an artificial substrate, with the shod condition involving a less dorsiflexed ankle, and the plantar flexion at toe‐off is more extreme when shod. Overall the activity pattern of the external foot muscles is similar.DiscussionThe indigenous footwear studied (Kolhapuri) seems to alter foot biomechanics only in a subtle way. While offering some degree of protection, walking in this type of footwear resembles barefoot gait and this type of indigenous footwear might be considered “minimal”.

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Section: Discussionmentioning

confidence: 99%

Biomechanical implications of walking with indigenous footwear

Willems¹,

Stassijns

Cornelis

et al. 2017

American J Phys Anthropol

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“…By simply increasing leg stiffness on softer elastic surfaces, hoppers and runners reduce leg compression to exactly offset the larger surface compression, thereby maintaining similar centre-of-mass dynamics (Ferris & Farley 1997;Ferris et al 1998Ferris et al , 1999Kerdok et al 2002). Leg behaviour can remain spring-like because elastic surfaces do not dissipate energy.…”

Section: Discussionmentioning

confidence: 99%

“…We calculated the overall 'vertical stiffness' of the leg and surface combination (k vert ) from the net force (F peak ) at the peak vertical displacement of the centre of mass (⌬y; Ferris et al 1998):…”

Section: Methodsmentioning

confidence: 99%

Human hopping on damped surfaces: strategies for adjusting leg mechanics

Moritz

Farley

2003

Proc. R. Soc. Lond. B

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Fast-moving legged animals bounce along the ground with spring-like legs and agilely traverse variable terrain. Previous research has shown that hopping and running humans maintain the same bouncing movement of the body's centre of mass on a range of elastic surfaces by adjusting their spring-like legs to exactly offset changes in surface stiffness. This study investigated human hopping on damped surfaces that dissipated up to 72% of the hopper's mechanical energy. On these surfaces, the legs did not act like pure springs. Leg muscles performed up to 24-fold more net work to replace the energy lost by the damped surface. However, considering the leg and surface together, the combination appeared to behave like a constant stiffness spring on all damped surfaces. By conserving the mechanics of the leg-surface combination regardless of surface damping, hoppers also conserved centre-of-mass motions. Thus, the normal bouncing movements of the centre of mass in hopping are not always a direct result of springlike leg behaviour. Conserving the trajectory of the centre of mass by maintaining spring-like mechanics of the leg-surface combination may be an important control strategy for fast-legged locomotion on variable terrain.

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“…Surface compliance and damping can affect locomotion energetics and dynamics (Ferris et al, 1998;Ferris et al, 1999;Kerdok et al, 2002), as do surface inclines or declines (Margaria, 1976;Minetti et al, 1993). However, few studies have characterized the biomechanics and energetics of walking on uneven surfaces.…”

Section: Discussionmentioning

confidence: 99%

Biomechanics and energetics of walking on uneven terrain

Voloshina

Kuo

Daley

et al. 2013

Journal of Experimental Biology

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214

186

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Summary Walking on uneven terrain is more energetically costly than walking on smooth ground, but the biomechanical factors that contribute to this increase are unknown. To identify possible factors, we constructed an uneven terrain treadmill that allowed us to record biomechanical, electromyographic, and metabolic energetics data from human subjects. We hypothesized that walking on uneven terrain would increase step width and length variability, joint mechanical work, and muscle co-activation compared to walking on smooth terrain. We tested healthy subjects (N=11) walking at 1.0 m/s, and found that, when walking on uneven terrain with up to 2.5 cm variation, subjects decreased their step length by 4% and did not significantly change their step width, while both step length and width variability increased significantly (22% and 36%, respectively; p<0.05). Uneven terrain walking caused a 28% and 62% increase in positive knee and hip work, and a 26% greater magnitude of negative knee work (0.0106, 0.1078, and 0.0425 J/kg, respectively; p<0.05). Mean muscle activity increased in seven muscles in the lower leg and thigh (p<0.05). These changes caused overall net metabolic energy expenditure to increase by 0.73 W/kg (28%; p<0.0001). Much of that increase could be explained by the increased mechanical work observed at the knee and hip. Greater muscle co-activation could also contribute to increased energetic cost but to unknown degree. The findings provide insight into how lower limb muscles are used differently for natural terrain compared to laboratory conditions.

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Running in the real world: adjusting leg stiffness for different surfaces

Cited by 491 publications

References 27 publications

Biomechanical implications of walking with indigenous footwear

Biomechanical implications of walking with indigenous footwear

Human hopping on damped surfaces: strategies for adjusting leg mechanics

Biomechanics and energetics of walking on uneven terrain

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