The double contact phase in walking children

Bastien, Guillaume; Heglund, Norman; Schepens, Bénédicte

doi:10.1242/jeb.00494

Cited by 33 publications

(52 citation statements)

References 26 publications

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“…The first part, W int,k , has previously been referred to simply as W int and can be measured using a cinematographic system (Cavagna and Kaneko, 1977;Willems et al, 1995). The second part, W int,dc , involves individual force recordings for each foot on separate force plates (Donelan et al, 2002;Bastien et al, 2003). During unloaded walking, W int,k represents up to ∼55% and W int,dc up to ∼17% of the total mechanical work done (Schepens et al, 2004).…”

Section: Methodsmentioning

confidence: 99%

“…The methods used to compute the internal work done by one leg against the other during the period of double contact (W int,dc ) are the same as in Bastien et al (2003), and are presented only briefly here.…”

Section: Positive Internal Work Done By One Leg Against the Othermentioning

confidence: 99%

“…The positive work done by the ground reaction forces was calculated independently for the back (W back ) and the front (W front ) limb from the time-integral of the power curves taking into account energy transfers, as explained in detail in Bastien et al (2003). In order to count only the work that is not already measured in W ext , the positive muscular work realized by one leg against the other (W int,dc ) during the DC phase ( Fig.…”

Section: Positive Internal Work Done By One Leg Against the Othermentioning

confidence: 99%

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The mechanics of head-supported load carriage by Nepalese porters

Bastien

Willems

Schepens

et al. 2016

Journal of Experimental Biology

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In the Everest valley of Nepal, because of the rugged mountain terrain, roads are nothing more than dirt paths and all material must be conveyed on foot. The Nepalese porters routinely carry headsupported loads, which often exceed their body mass, over long distances up and down the steep mountain footpaths. In Africa, women transport their loads economically thanks to an energy-saving gait adaptation. We hypothesized that the Nepalese porters may have developed a corresponding mechanism. To investigate this proposition, we measured the mechanical work done during level walking in Nepalese porters while carrying different loads at several speeds. Our results show that the Nepalese porters do not use an equivalent mechanism as the African women to reduce work. In contrast, the Nepalese porters develop an equal amount of total mechanical work as Western control subjects while carrying loads of 0 to 120% of their body mass at all speeds measured (0.5-1.7 m s −1 ), making even more impressive their ability to carry loads without any apparent mechanically determined tricks. Nevertheless, our results show that the Nepalese porters have a higher efficiency, at least at slow speeds and high loads.

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Section: Methodsmentioning

confidence: 99%

Section: Positive Internal Work Done By One Leg Against the Othermentioning

confidence: 99%

Section: Positive Internal Work Done By One Leg Against the Othermentioning

confidence: 99%

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The mechanics of head-supported load carriage by Nepalese porters

Bastien

Willems

Schepens

et al. 2016

Journal of Experimental Biology

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“…The direct coupling of stride and metabolic rates identifies the rates at which the movements of each stride are completed as a crucial determinant of mass-specific metabolic rates. By contrast, existing literature amply indicates that the size-dependent economy of human walking is not explained by existing measures of the rates at which mechanical work is performed (Cavagna et al, 1983;Bastien et al, 2003;Schepens et al, 2004;Donelan et al, 2002;Kuo et al, 2005).…”

Section: Equivalent Speeds and Energy Expenditure In Walking Gaitsmentioning

confidence: 97%

“…Ontogenetic approaches have appropriately considered both maturation (DeJaeger et al, 2001;Morgan et al, 2002) and body size (McCann and Adams, 2002) but have not resolved their quantitative importance. Mechanical approaches have estimated that the mass-specific mechanical work that small children and adults perform during walking differs only marginally (Cavagna et al, 1983;Bastien et al, 2003;Schepens et al, 2004) and therefore does not account (Schepens et al, 2004) for the much larger differences observed in metabolic cost. The current lack of quantitative understanding is reflected in the use of different generalized equations to estimate the energy expended by adult (ACSM, 2006;Pandolf et al, 1971) and child populations (Morgan et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

The mass-specific energy cost of human walking is set by stature

Weyand

Smith

Puyau

et al. 2010

Journal of Experimental Biology

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SUMMARYThe metabolic and mechanical requirements of walking are considered to be of fundamental importance to the health, physiological function and even the evolution of modern humans. Although walking energy expenditure and gait mechanics are clearly linked, a direct quantitative relationship has not emerged in more than a century of formal investigation. Here, on the basis of previous observations that children and smaller adult walkers expend more energy on a per kilogram basis than larger ones do, and the theory of dynamic similarity, we hypothesized that body length (or stature, L b ) explains the apparent body-size dependency of human walking economy. We measured metabolic rates and gait mechanics at six speeds from 0.4 to 1.9ms -1 in 48 human subjects who varied by a factor of 1.5 in stature and approximately six in both age and body mass. In accordance with theoretical expectation, we found the most economical walking speeds measured (Jkg ). We conclude that humans spanning a broad range of ages, statures and masses incur the same mass-specific metabolic cost to walk a horizontal distance equal to their stature. Supplementary material available online at

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Patterns of mechanical energy change in tetrapod gait: pendula, springs and work

Biewener

2006

J. Exp. Zool.

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Kinematic and center of mass (CoM) mechanical variables used to define terrestrial gaits are compared for various tetrapod species. Kinematic variables (limb phase, duty factor) provide important timing information regarding the neural control and limb coordination of various gaits. Whereas, mechanical variables (potential and kinetic energy relative phase, %Recovery, %Congruity) provide insight into the underlying mechanisms that minimize muscle work and the metabolic cost of locomotion, and also influence neural control strategies. Two basic mechanisms identified by Cavagna et al. (1977. Am J Physiol 233:R243-R261) are used broadly by various bipedal and quadrupedal species. During walking, animals exchange CoM potential energy (PE) with kinetic energy (KE) via an inverted pendulum mechanism to reduce muscle work. During the stance period of running (including trotting, hopping and galloping) gaits, animals convert PE and KE into elastic strain energy in spring elements of the limbs and trunk and regain this energy later during limb support. The bouncing motion of the body on the support limb(s) is well represented by a simple mass-spring system. Limb spring compliance allows the storage and return of elastic energy to reduce muscle work. These two distinct patterns of CoM mechanical energy exchange are fairly well correlated with kinematic distinctions of limb movement patterns associated with gait change. However, in some cases such correlations can be misleading. When running (or trotting) at low speeds many animals lack an aerial period and have limb duty factors that exceed 0.5. Rather than interpreting this as a change of gait, the underlying mechanics of the body's CoM motion indicate no fundamental change in limb movement pattern or CoM dynamics has occurred. Nevertheless, the idealized, distinctive patterns of CoM energy fluctuation predicted by an inverted pendulum for walking and a bouncing mass spring for running are often not clear cut, especially for less cursorial species. When the kinematic and mechanical patterns of a broader diversity of quadrupeds and bipeds are compared, more complex patterns emerge, indicating that some animals may combine walking and running mechanics at intermediate speeds or at very large size. These models also ignore energy costs that are likely associated with the opposing action of limbs that have overlapping support times during walking. A recent model of terrestrial gait (Ruina et al., 2005. J Theor Biol, in press) that treats limb contact with the ground in terms of collisional energy loss indicates that considerable CoM energy can be conserved simply by matching the path of CoM motion perpendicular to limb ground force. This model, coupled with the earlier ones of pendular exchange during walking and mass-spring elastic energy savings during running, provides compelling argument for the view that the legged locomotion of quadrupeds and other terrestrial animals has generally evolved to minimize muscle work during steady level movement.

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The double contact phase in walking children

Cited by 33 publications

References 26 publications

The mechanics of head-supported load carriage by Nepalese porters

The mechanics of head-supported load carriage by Nepalese porters

The mass-specific energy cost of human walking is set by stature

Patterns of mechanical energy change in tetrapod gait: pendula, springs and work

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