The effect of walking speed on muscle function and mechanical energetics

Neptune, Richard R.; Sasaki, Kotaro; Kautz, Steven A.

doi:10.1016/j.gaitpost.2007.11.004

Cited by 340 publications

(345 citation statements)

References 34 publications

(53 reference statements)

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“…In addition to the lower shortening velocities of soleus observed here, this monoarticular muscle has been suggested to make a larger contribution to ankle torque, make greater use of elastic energy storage and reuse, and be metabolically more efficient than the biarticular MG in walking (Krishnaswamy et al, 2011;Neptune et al, 2008). Soleus also has a larger cross-sectional area (Ward et al, 2009) and shorter fascicles than either gastrocnemius head (Maganaris et al, 1998), reducing the required activation volume for a given force.…”

Section: Discussionmentioning

confidence: 68%

“…For example, oxygen consumption has also been found to remain constant when running for an equivalent period of time (Finni et al, 2003). In addition, at walking speeds where COT is minimised, Achilles tendon storage and return of elastic energy (Neptune et al, 2008) and muscular efficiency (Cavagna and Kaneko, 1977) have been suggested to be maximal. Knee joint flexion in the stance phase is also minimal around optimal COT, which is associated with decreased cost of muscle work (Winter, 1983).…”

Section: The Evolutionary Origins Of Human Walkingmentioning

confidence: 99%

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Differences in contractile behaviour between the soleus and medial gastrocnemius muscles during human walking

Cronin

Avela

Finni

et al. 2012

Journal of Experimental Biology

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SUMMARYThe functional roles of individual lower limb muscles during human walking may differ depending on walking speed or duration. In this study, 11 volunteers walked on a treadmill for 60min at speeds corresponding to both optimal and 20% above optimal energetic cost of transport whilst oxygen consumption and medial gastrocnemius (MG) and soleus fascicle lengths were measured. Although energetic cost of transport was ~12% higher at the faster speed, it remained constant over 60min at both speeds, suggesting that humans can walk for prolonged periods at a range of speeds without compromising energetic efficiency. The fascicles of both muscles exhibited rather ʻisometricʼ behaviour during the early to mid stance phase of walking, which appears to be independent of walking speed or movement efficiency. However, several functional differences were observed between muscles. MG exhibited time-and speed-dependent decreases in operating length, and shortened faster during the pushoff phase at the faster walking speed. Conversely, soleus exhibited consistent contractile behaviour regardless of walking speed or duration, and always shortened slower than MG during pushoff. Soleus appears to play a more important functional role than MG during walking. This may be especially true when walking for prolonged periods or at speeds above the most energetically efficient, where the force potential and thus the functional importance of MG appears to decline.

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Section: Discussionmentioning

confidence: 68%

Section: The Evolutionary Origins Of Human Walkingmentioning

confidence: 99%

Differences in contractile behaviour between the soleus and medial gastrocnemius muscles during human walking

Cronin

Avela

Finni

et al. 2012

Journal of Experimental Biology

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“…Preferred speeds were chosen rather than a set speed given that they are known to be related to minimal energy expenditure (Ralston, 1958;Rubenson et al, 2007) and optimal muscle-tendon function (Neptune et al, 2008).…”

Section: Force-length Operating Range During Walking and Runningmentioning

confidence: 99%

On the ascent: the soleus operating length is conserved to the ascending limb of the force-length curve across gait mechanics in humans

Rubenson

Pires

Loi

et al. 2012

Journal of Experimental Biology

103

110

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SUMMARYThe region over which skeletal muscles operate on their force-length (F-L) relationship is fundamental to the mechanics, control and economy of movement. Yet surprisingly little experimental data exist on normalized length operating ranges of muscle during human gait, or how they are modulated when mechanical demands (such as force output) change. Here we explored the soleus muscle (SOL) operating lengths experimentally in a group of healthy young adults by combining subject-specific F-L relationships with in vivo muscle imaging during gait. We tested whether modulation of operating lengths occurred between walking and running, two gaits that require different levels of force production and different muscle-tendon mechanics, and examined the relationship between optimal fascicle lengths (L 0 ) and normalized operating lengths during these gaits. We found that the mean active muscle lengths reside predominantly on the ascending limbs of the F-L relationship in both gaits (walk, 0.70-0.94 L 0 ; run, 0.65-0.99 L 0 ). Furthermore, the mean normalized muscle length at the time of the peak activation of the muscle was the same between the two gaits (0.88 L 0 ). The active operating lengths were conserved, despite a fundamentally different fascicle strain pattern between walking (stretch-shorten cycle) and running (near continuous shortening). Taken together, these findings indicate that the SOL operating length is highly conserved, despite gait-dependent differences in muscle-tendon dynamics, and appear to be preferentially selected for stable force production compared with optimal force output (although length-dependent force capacity is high when maximal forces are expected to occur). Individuals with shorter L 0 undergo smaller absolute muscle excursions (P<0.05) so that the normalized length changes during walking and running remain independent of L 0 . The correlation between L 0 and absolute length change was not explained on the basis of muscle moment arms or joint excursion, suggesting that regulation of muscle strain may occur via tendon stretch.

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“…We aimed to acquire in vivo evidence to provide support for and help validate previous findings from modeling studies (5,11,12,18). To achieve this, we combined ultrasound imaging of medial gastrocnemius (MG) muscle fascicles and an inverse-dynamics analysis during walking and running.…”

mentioning

confidence: 97%

Human medial gastrocnemius force–velocity behavior shifts with locomotion speed and gait

Farris

Sawicki

2012

Proc. Natl. Acad. Sci. U.S.A.

209

265

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Humans walk and run over a wide range of speeds with remarkable efficiency. For steady locomotion, moving at different speeds requires the muscle-tendon units of the leg to modulate the amount of mechanical power the limb absorbs and outputs in each step. How individual muscles adapt their behavior to modulate limb power output has been examined using computer simulation and animal models, but has not been studied in vivo in humans. In this study, we used a combination of ultrasound imaging and motion analysis to examine how medial gastrocnemius (MG) muscletendon unit behavior is adjusted to meet the varying mechanical demands of different locomotor speeds during walking and running in humans. The results highlighted key differences in MG fascicle-shortening velocity with both locomotor speed and gait. Fascicle-shortening velocity at the time of peak muscle force production increased with walking speed, impairing the ability of the muscle to produce high peak forces. Switching to a running gait at 2.0 m·s −1 caused fascicle shortening at the time of peak force production to shift to much slower velocities. This velocity shift facilitated a large increase in peak muscle force and an increase in MG power output. MG fascicle velocity may be a key factor that limits the speeds humans choose to walk at, and may explain the transition from walking to running. This finding is consistent with previous modeling studies.muscle mechanics | biomechanics | preferred transition speed A nkle plantar-flexor muscles are a vital source of mechanical power for human locomotion (1, 2). During walking, plantar-flexor muscles provide body weight support, contribute to propulsion, and accelerate the limb into swing (3). In running, the ankle acts in a spring-like manner, absorbing energy in plantarflexor muscle-tendon units during early stance and providing energy to accelerate the body in late stance (1). The mechanical work required to produce whole-body movement during walking and running varies between gaits and across speeds (4, 5). Thus, the plantar-flexors may need to adjust their mechanical work output with gait and speed to meet the changing demands on their contribution to total mechanical work.A recent experimental study in humans used an inverse-dynamics approach to examine how the mechanical power outputs of muscles acting at the hip, knee, and ankle joint were modulated for walking and running at a range of speeds (6). It was found that positive power output at the ankle, in conjunction with the knee and hip, increased with walking speed. Also, Hansen et al. (7) showed that at walking speeds above those preferred, the net positive work done at the ankle increased. When switching from walking to running gait, the relative contribution of ankle positive power output to total positive power output also increased (6). It was inferred from these data that plantar-flexor muscle mechanics were adjusted to accommodate faster walking speeds and then again with the switch to running gait. If this is truly the case, then it may hav...

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The effect of walking speed on muscle function and mechanical energetics

Cited by 340 publications

References 34 publications

Differences in contractile behaviour between the soleus and medial gastrocnemius muscles during human walking

Differences in contractile behaviour between the soleus and medial gastrocnemius muscles during human walking

On the ascent: the soleus operating length is conserved to the ascending limb of the force-length curve across gait mechanics in humans

Human medial gastrocnemius force–velocity behavior shifts with locomotion speed and gait

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