The Architecture of Leg Muscles

Alexander, R. McNeill; Ker, R. F.

doi:10.1007/978-1-4613-9030-5_36

Cited by 46 publications

(51 citation statements)

References 22 publications

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“…In their view, knee extensor and calf muscle contractile elements do not undergo any (active) lengthening during running but allow their relatively long tendinous tissue to store elastic energy during stretch, with the muscles acting primarily as force generators (Rall, 1985;Taylor, 1980). We are sympathetic with the arguments forwarded in support of this view, which are derived from muscle architecture considerations (e.g., Alexander & Goldspink, 1977;Alexander & Ker, 1990), experimental results (e.g., Hof, 1990;Jacobs et al, 1993;Tidball & Daniel, 1986), and teleological considerations (Winters, 1990). However, we do not subscribe to the view that the muscles merely act as force generators.…”

Section: Is Efficiency In Sscs a Relevant Concept?mentioning

confidence: 73%

“…Considering what was said in the previous paragraph, it remains to be seen whether stretch reflexes occur at all. If the contributions during CMJ and other SSCs not requiring absorption of large amounts of mechanical energy are indeed concerted, as suggested by some authors (e.g., Alexander & Ker, 1990;Belli & Bosco, 1992;Hof, 1990;Jacobs et al, 1993;Rall, 1985;Voigt, Boysen-Mgller, et al, 1995), there is no lengthening of muscle spindles and thus no trigger for stretch reflexes.…”

Section: The Contribution Of Reflexesmentioning

confidence: 89%

“…It is questionable, however, whether potentiation plays a role in SSCs occurring in vivo, where prestretch speeds are relatively low and the switch from lengthening to shortening occurs gradually. As a matter of fact, it remains to be seen whether the muscle fibers are lengthened at all; several authors (e.g., Alexander & Ker, 1990;Belli & Bosco, 1992;Hof, 1990;Jacobs, Bobbert, & Ingen Schenau, 1993;Rall, 1985;Voigt, Bojsen-Mflller, Simonsen, & Dyhre-Poulsen, 1995) have suggested that during SSCs in vivo, the knee extensors and plantar flexors are activated in such a way that a concerted contraction occurs, that is, a contraction where the entire muscle-tendon complex is lengthened but the muscle fibers remain isometric or even shorten during the prestretch.…”

Section: Potentiation Of the Contractile Machinerymentioning

confidence: 99%

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Does Elastic Energy Enhance Work and Efficiency in the Stretch-Shortening Cycle?

Schenau¹,

Bobbert²,

Haan³

1997

Journal of Applied Biomechanics

186

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This target article addresses the role of storage and reutilization of elastic energy in stretch-shortening cycles. It is argued that for discrete movements such as the vertical jump, elastic energy does not explain the work enhancement due to the prestretch. This enhancement seems to occur because the prestretch allows muscles to develop a high level of active state and force before starting to shorten. For cyclic movements in which stretch-shortening cycles occur repetitively, some authors have claimed that elastic energy enhances mechanical efficiency. In the current article it is demonstrated that this claim is often based on disputable concepts such as the efficiency of positive work or absolute work, and it is argued that elastic energy cannot affect mechanical efficiency simply because this energy is not related to the conversion of metabolic energy into mechanical energy. A comparison of work and efficiency measures obtained at different levels of organization reveals that there is in fact no decisive evidence to either support or reject the claim that the stretch-shortening cycle enhances muscle efficiency. These explorations lead to the conclusion that the body of knowledge about the mechanics and energetics of the stretch-shortening cycle is in fact quite lean. A major challenge is to bridge the gap between knowledge obtained at different levels of organization, with the ultimate purpose of understanding how the intrinsic properties of muscles manifest themselves under in-vivo-like conditions and how they are exploited in whole-body activities such as running. To achieve this purpose, a close cooperation is required between muscle physiologists and human movement scientists performing inverse and forward dynamic simulation studies of whole-body exercises.

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Section: Is Efficiency In Sscs a Relevant Concept?mentioning

confidence: 73%

Section: The Contribution Of Reflexesmentioning

confidence: 89%

Section: Potentiation Of the Contractile Machinerymentioning

confidence: 99%

See 1 more Smart Citation

Does Elastic Energy Enhance Work and Efficiency in the Stretch-Shortening Cycle?

Schenau¹,

Bobbert²,

Haan³

1997

Journal of Applied Biomechanics

186

View full text Add to dashboard Cite

show abstract

“…Within the leg-spring, the ankle is the least stiff joint and has been shown to regulate vertical stiffness in bilateral hopping (Farley et al, 1998;Farley & Morgenroth, 1999;Kim et al, 2013;Kuitunen et al, 2011) and drop jumping (Arampatzis et al, 2001). Conversely, adjustments in knee stiffness appear important in optimising torque output rather than in the modulation of vertical stiffness (Kuitunen et al, 2011); the anatomy of the knee extensors in relation to the plantar flexors facilitates greater moments at the knee versus the ankle (Alexander & Ker, 1990). Comparisons between the fast and slow groups (Table 4) suggest a potential reliance on different movement strategies during the drop jump; the fast group exhibit 'moderately' greater ankle stiffness but lower values for knee and hip stiffness.…”

Section: Discussionmentioning

confidence: 99%

Do stiffness and asymmetries predict change of direction performance?

Maloney

Richards

Nixon

et al. 2016

Journal of Sports Sciences

150

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Change of direction speed (CODS) underpins performance in a wide range of sports but little is known about how stiffness and asymmetries affect CODS. Eighteen healthy males performed unilateral drop jumps to determine vertical, ankle, knee and hip stiffness, and a CODS test to evaluate left and right leg cutting performance during which ground reaction force data were sampled. A step-wise regression analysis was performed to ascertain the determinants of CODS time. A two-variable regression model explained 63% (R 2 = 0.63; P = 0.001) of CODS performance. The model included the mean vertical stiffness and jump height asymmetry determined during the drop jump. Faster athletes (n = 9) exhibited greater vertical stiffness (F = 12.40; P = 0.001) and less asymmetry in drop jump height (F = 6.02; P = 0.026) than slower athletes (n = 9); effect sizes were both 'large' in magnitude. Results suggest that overall vertical stiffness and drop jump height asymmetry are the strongest predictors of CODS in a healthy, non-athletic population.

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“…Additionally, most studies examining scaling of architectural variables have looked at how absolute rather than relative variables scale with body size. One study examining scaling of relative variables normalized fiber length to femur length and grouped muscles according to action (Alexander and Ker, 1990). It was concluded from this analysis that relative fiber lengths did not scale with body mass.…”

Section: Introductionmentioning

confidence: 99%

Scaling of muscle architecture and fiber types in the rat hindlimb

Eng¹,

Smallwood²,

Rainiero³

et al. 2008

Journal of Experimental Biology

166

201

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SUMMARYThe functional capacity of a muscle is determined by its architecture and metabolic properties. Although extensive analyses of muscle architecture and fiber type have been completed in a large number of muscles in numerous species, there have been few studies that have looked at the interrelationship of these functional parameters among muscles of a single species. Nor have the architectural properties of individual muscles been compared across species to understand scaling. This study examined muscle architecture and fiber type in the rat (Rattus norvegicus) hindlimb to examine each muscle's functional specialization. Discriminant analysis demonstrated that architectural properties are a greater predictor of muscle function (as defined by primary joint action and anti-gravity or non anti-gravity role) than fiber type. Architectural properties were not strictly aligned with fiber type, but when muscles were grouped according to anti-gravity versus non-anti-gravity function there was evidence of functional specialization. Specifically, anti-gravity muscles had a larger percentage of slow fiber type and increased muscle physiological cross-sectional area. Incongruities between a muscle's architecture and fiber type may reflect the variability of functional requirements on single muscles, especially those that cross multiple joints. Additionally, discriminant analysis and scaling of architectural variables in the hindlimb across several mammalian species was used to explore whether any functional patterns could be elucidated within single muscles or across muscle groups. Several muscles deviated from previously described muscle architecture scaling rules and there was large variability within functional groups in how muscles should be scaled with body size. This implies that functional demands placed on muscles across species should be examined on the single muscle level.

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The Architecture of Leg Muscles

Cited by 46 publications

References 22 publications

Does Elastic Energy Enhance Work and Efficiency in the Stretch-Shortening Cycle?

Does Elastic Energy Enhance Work and Efficiency in the Stretch-Shortening Cycle?

Do stiffness and asymmetries predict change of direction performance?

Scaling of muscle architecture and fiber types in the rat hindlimb

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