Muscular Force in Running Turkeys: The Economy of Minimizing Work

Roberts, Thomas J.; Marsh, Richard L.; Weyand, Peter G.; Taylor, Cameron R.

doi:10.1126/science.275.5303.1113

Cited by 681 publications

(756 citation statements)

References 21 publications

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“…Of course, if that is the case it is difficult to explain how a muscle can contribute to external work (De Haan et al 1989). Roberts et al (1997), however, showed that in the gastrocnemius muscle of turkeys who ran on the level, no stretch of the contractile elements occurred. Furthermore, Kram and Taylor (1990) based their cost-ofgenerating-force hypothesis on the idea that during level running the contractile elements of the muscle operate isometrically.…”

Section: Discussionmentioning

confidence: 93%

Differences in leg muscle activity during running and cycling in humans

Bijker

Groot

Hollander

2002

European Journal of Applied Physiology

117

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Delta (D) efficiency is defined as the ratio of an increment in the external mechanical power output to the increase in metabolic power required to produce it. The purpose of the present study was to investigate whether differences in leg muscle activity between running and cycling can explain the observed difference in D efficiency between the two activities. A group of 11 subjects performed incremental submaximal running and cycling tests on successive days. The D efficiencies during running and cycling were based on five exercise stages. Electromyograph (EMG) measurements were made of three leg muscles (gastrocnemius, vastus lateralis and biceps femoris). Kendall's correlation coefficients between the mean EMG activity and the load applied were calculated for each muscle, for both running and cycling. As expected, the mean D efficiency during running (42%) was significantly greater than that during cycling (25%). For cycling, all muscles showed a significant correlation between mean EMG activity and the load applied. For running, however, only the gastrocnemius muscle showed a significant, but low correlation (r=0.33). The correlation coefficients of the vastus lateralis and biceps femoris muscles were not significantly different from 0. The results were interpreted as follows. In contrast to cycling, which includes only concentric contractions, during running up inclines eccentric muscle actions play an important role. With steeper inclines, more concentric contractions must be produced to overcome the external force, whereas the amount of eccentric muscle actions decreases. This change in the relative contribution of concentric and eccentric muscle actions, in combination with the fact that eccentric muscle actions require much less metabolic energy than concentric contractions, can explain the difference between the running and cycling D efficiency.

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Section: Discussionmentioning

confidence: 93%

Differences in leg muscle activity during running and cycling in humans

Bijker

Groot

Hollander

2002

European Journal of Applied Physiology

117

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“…Alternatively, it is possible that leg sti¡-ness adjustments indirectly result from the control of a lower level neuromuscular parameter (e.g. minimizing muscle ¢bre displacement during ground contact; (Roberts et al 1997). Further studies exploring the link between muscle^tendon action and leg sti¡ness should provide a better physiological understanding of leg sti¡-ness adjustments during running.…”

Section: Discussionmentioning

confidence: 99%

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

Ferris

Louie

Farley

1998

Proc. R. Soc. Lond. B

491

394

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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 sti¡ness is independent of both speed and gravity level, suggesting that it is dictated by inherent musculoskeletal properties. However, if leg sti¡ness was invariant, the biomechanics of running (e.g. peak ground reaction force and ground contact time) would change when an animal encountered di¡erent surfaces in the natural world. We found that human runners adjust their leg sti¡ness to accommodate changes in surface sti¡ness, allowing them to maintain similar running mechanics on di¡erent surfaces. These results provide important insight into the mechanics and control of animal locomotion and suggest that incorporating an adjustable leg sti¡ness 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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“…During running, there is little energy saved by pendular-energy conservation because the gravitational potential energy and kinetic energy of the COM fluctuate in phase. Instead, the spring-like properties of muscles and tendons in the stance phase of running result in an exchange between the kinetic energy of the COM and the elastic energy stored in these tissues (Cavagna et al 1964(Cavagna et al , 1977Ker et al 1987;Roberts et al 1997). At fast speeds, when the inverted-pendulum mechanism of walking is impaired, this bouncing gait provides a highly effective means of reducing the metabolic cost of locomotion.…”

Section: Introductionmentioning

confidence: 99%

Gait selection in the ostrich: mechanical and metabolic characteristics of walking and running with and without an aerial phase

Rubenson

Heliams²,

Lloyd

et al. 2004

Proc. R. Soc. Lond. B

175

259

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It has been argued that minimization of metabolic-energy costs is a primary determinant of gait selection in terrestrial animals. This view is based predominantly on data from humans and horses, which have been shown to choose the most economical gait (walking, running, galloping) for any given speed. It is not certain whether a minimization of metabolic costs is associated with the selection of other prevalent forms of terrestrial gaits, such as grounded running (a widespread gait in birds). Using biomechanical and metabolic measurements of four ostriches moving on a treadmill over a range of speeds from 0.8 to 6.7 m s -1 , we reveal here that the selection of walking or grounded running at intermediate speeds also favours a reduction in the metabolic cost of locomotion. This gait transition is characterized by a shift in locomotor kinetics from an inverted-pendulum gait to a bouncing gait that lacks an aerial phase. By contrast, when the ostrich adopts an aerial-running gait at faster speeds, there are no abrupt transitions in mechanical parameters or in the metabolic cost of locomotion. These data suggest a continuum between grounded and aerial running, indicating that they belong to the same locomotor paradigm.

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Muscular Force in Running Turkeys: The Economy of Minimizing Work

Cited by 681 publications

References 21 publications

Differences in leg muscle activity during running and cycling in humans

Differences in leg muscle activity during running and cycling in humans

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

Gait selection in the ostrich: mechanical and metabolic characteristics of walking and running with and without an aerial phase

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