Effects of load carrying on metabolic cost and hindlimb muscle dynamics in guinea fowl (<i>Numida meleagris</i>)

McGowan, Craig P.; Duarte, Horacio A.; Main, Joyce B.; Biewener, Andrew A.

doi:10.1152/japplphysiol.01538.2005

Cited by 32 publications

(51 citation statements)

References 46 publications

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“…2 and Table 1). Running guinea fowl similarly show no change in MG fascicle velocity with running speed (16). These data support the assumption of Kram and Taylor (26) that muscles are working on a similar part of their force-velocity relationship across all steady-state running speeds.…”

Section: Discussionsupporting

confidence: 84%

“…Using sonomicrometry and tendon buckle transducers, Prilutsky et al (15) showed that the velocity of cat gastrocnemius fibers increased with walking speed, impairing gastrocnemius force production at faster speeds. In running guinea fowl (16) and turkeys (17), ankle extensors operate at low fascicle-shortening velocities, supporting the notion that running gait allows distal leg muscles to operate under favorable conditions for force production. However, these animal data come from varied species and may not translate well to humans.…”

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confidence: 59%

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

Farris

Sawicki

2012

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

207

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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Section: Discussionsupporting

confidence: 84%

mentioning

confidence: 59%

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

Farris

Sawicki

2012

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

207

265

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“…Note that the stance active ILPO can itself be considered a neuromuscular compartment of the iliotibialis lateralis because in most species it is contiguous with the iliotibialis lateralis preacetabularis, which is active during swing phase (Gatesy, 1999b). Whether further differences in function occur along the anterior-posterior axis within the ILPO has not been revealed in previous studies (Buchanan, 1999;McGowan et al, 2006;Roberts et al, 2007).…”

Section: Introductionmentioning

confidence: 97%

Mechanisms producing coordinated function across the breadth of a large biarticular thigh muscle

Carr

Ellerby

Rubenson

et al. 2011

Journal of Experimental Biology

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SUMMARYWe examined the hypothesis that structural features of the iliotibialis lateralis pars postacetabularis (ILPO) in guinea fowl allow this large muscle to maintain equivalent function along its anterior-posterior axis. The ILPO, the largest muscle in the hindlimb of the guinea fowl, is a hip and knee extensor. The fascicles of the ILPO originate across a broad region of the ilium and ischium posterior to the hip. Its long posterior fascicles span the length of the thigh and insert directly on the patellar tendon complex. However, its anterior fascicles are shorter and insert on a narrow aponeurosis that forms a tendinous band along the anterior edge of the muscle and is connected distally to the patellar tendon. The biarticular ILPO is actively lengthened and then actively shortened during stance. The moment arm of the fascicles at the hip increases along the anterior to posterior axis, whereas the moment arm at the knee is constant for all fascicles. Using electromyography and sonomicrometry, we examined the activity and strain of posterior and anterior fascicles of the ILPO. The activation was not significantly different in the anterior and posterior fascicles. Although we found significant differences in active lengthening and shortening strain between the anterior and posterior fascicles, the differences were small. The majority of shortening strain is caused by hip extension and the inverse relationship between hip moment arm and fascicle length along the anterior-posterior axis was found to have a major role in ensuring similar shortening strain. However, because the knee moment arm is the same for all fascicles, knee flexion in early stance was predicted to produce much larger lengthening strains in the short anterior fascicles than our measured values at this location. We propose that active lengthening of the anterior fascicles was lower than predicted because the aponeurotic tendon of insertion of the anterior fascicles was stretched and only a portion of the lengthening had to be accommodated by the active muscle fascicles.

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“…The function of substantial active lengthening of this large muscle is not clear. Other researchers have suggested that the active lengthening-shortening cycle might enhance economy of force production (McGowan et al, 2006;Roberts et al, 2007). However, active lengthening of muscle fibers beyond their short-range elasticity absorbs work that cannot be recovered, and replacing this negative work could increase the cost of legged locomotion (see Discussion).…”

Section: Introductionmentioning

confidence: 95%

“…Previous studies have demonstrated that during running the ILPO in the guinea fowl and turkey actively lengthens and absorbs work during the first part of stance, then actively shortens to produce work during the latter half of stance (Buchanan, 1999;Marsh, 1999;McGowan et al, 2006;Roberts et al, 2007). The function of substantial active lengthening of this large muscle is not clear.…”

Section: Introductionmentioning

confidence: 99%

Function of a large biarticular hip and knee extensor during walking and running in guinea fowl (Numida meleagris)

Carr

Ellerby

Marsh

2011

Journal of Experimental Biology

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SUMMARYPhysiological and anatomical evidence suggests that in birds the iliotibialis lateralis pars postacetabularis (ILPO) is functionally important for running. Incorporating regional information, we estimated the mean sarcomere strain trajectory and electromyographic (EMG) amplitude of the ILPO during level and incline walking and running. Using these data and data in the literature of muscle energy use, we examined three hypotheses: (1) active lengthening will occur on the ascending limb of the length-tension curve to avoid potential damage caused by stretch on the descending limb; (2) the active strain cycle will shift to favor active shortening when the birds run uphill and shortening will occur on the plateau and shallow ascending limb of the length-tension curve; and (3) measures of EMG intensity will correlate with energy use when the mechanical function of the muscle is similar. Supporting the first hypothesis, we found that the mean sarcomere lengths at the end of active lengthening during level locomotion were smaller than the predicted length at the start of the plateau of the length-tension curve. Supporting the second hypothesis, the magnitude of active lengthening decreased with increasing slope, whereas active shortening increased. In evaluating the relationship between EMG amplitude and energy use (hypothesis 3), we found that although increases in EMG intensity with speed, slope and loading were positively correlated with muscle energy use, the quantitative relationships between these variables differed greatly under different conditions. The relative changes in EMG intensity and energy use by the muscle probably varied because of changes in the mechanical function of the muscle that altered the ratio of muscle energy use to active muscle volume. Considering the overall function of the cycle of active lengthening and shortening of the fascicles of the ILPO, we conclude that the function of active lengthening is unlikely to be energy conservation and may instead be related to promoting stability at the knee. The work required to lengthen the ILPO during stance is provided by co-contracting knee flexors. We suggest that this potentially energetically expensive co-contraction serves to stabilize the knee in early stance by increasing the mechanical impedance of the joint.

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Effects of load carrying on metabolic cost and hindlimb muscle dynamics in guinea fowl (Numida meleagris)

Cited by 32 publications

References 46 publications

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

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

Mechanisms producing coordinated function across the breadth of a large biarticular thigh muscle

Function of a large biarticular hip and knee extensor during walking and running in guinea fowl (Numida meleagris)

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