Dependence of jumping performance on muscle properties when humans use only calf muscles for propulsion

Zajac, Felix E.; Wicke, R. W.; Levine, William S.

doi:10.1016/0021-9290(84)90019-8

Cited by 35 publications

(23 citation statements)

References 19 publications

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“…smaller peak vertical ground reaction forces in higher jumps) is largely due to the diVerent motor strategies and biomechanical conWgurations, thus conWrming the explanation proposed by Vanrenterghem et al (2004). As reported in the literature, comparatively high GRF values can be generated by the use of only the ankle plantar Xexors in a vertical jump (Dowling and Vamos 1993;Fukashiro and Komi 1987;Zajac et al 1984). Furthermore, the movement to execute a jump from 90° knee angle (maximal jumps) depends mainly on the contribution of the energy generated by the hip and knee bi-articular muscles (e.g.…”

Section: Discussionmentioning

confidence: 52%

Differential effects of countermovement magnitude and volitional effort on vertical jumping

2010

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The importance of vertical jumping in sport and rehabilitative medicine is widely recognized. Despite the ample use of jump tests to assess neuromuscular function, the differential effects of muscular activation (volitional effort) and strategy (countermovement magnitude) on jumping performance have not been studied. The present study aimed to investigate the differential effects of countermovement magnitude and volitional effort on vertical jump performance. Ten male participants performed a total of 60 countermovement jumps each with three different countermovement knee angles (50, 70 and 90°) and four effort levels (25, 50, 75 and 100% of maximal effort). Kinematics and Kinetics were recorded using Vicon System together with a force platform. Electromyography of four muscles was recorded. Results show that countermovement magnitude and volitional effort both affect jump performance. These effects were synergistic for jump height (P < 0.001), but antagonistic for peak ground reaction force (P < 0.001). Interestingly, peak jump mechanical power was affected by volitional effort, implying an increase from 31.26 W/kg at 25% to 41.68 W/kg at 100% of volitional effort, but no countermovement magnitude effect was observed for 100% of volitional effort. This suggests that the apparent paradox of larger ground reaction forces in sub-maximal as compared to maximal jumps is due to the different jump strategies. Moreover, these results are relevant for jumping mechanography as a clinical tool, suggesting that peak power can be used to assess neuromuscular performance even when countermovement magnitude varies as a result of age or pathology.

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Section: Discussionmentioning

confidence: 52%

Differential effects of countermovement magnitude and volitional effort on vertical jumping

2010

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“…Each muscle group was activated once during the simulation, Time constant for muscle activation 10 ms 5 ms (Winters and Stark, 1985) 100 ms (Zajac et al, 1984) t d Time constant for muscle de-activation 30 ms 5 ms (Winters and Stark, 1985) 200 ms (Pandy et al, 1992) (Zajac, 1989) 0.10 L SEsl (Bobbert, 2001) WIDTH…”

Section: Methodsmentioning

confidence: 99%

“…Musculoskeletal models have been found to be sensitive to tendon slack length (L SEsl ), optimal muscle fibre length (L CEopt ) and muscle moment arm (Hoy et al, 1990;Maganaris, 2004;Out et al, 1996), as well as the muscle activation time constant (t a ) (Nagano and Gerritsen, 2001;Zajac et al, 1984). Other parameters were found to have a low sensitivity in a musculoskeletal model, including the parallel elastic element (PE) parameters (Out et al, 1996), pennation angle (Maganaris, 2004;Zajac, 1989) and muscle deactivation time constant (t d ) (Piazza and Delp, 1996).…”

Section: Introductionmentioning

confidence: 97%

Sensitivity of a Hill-based muscle model to perturbations in model parameters

Scovil

Ronsky

2006

Journal of Biomechanics

186

157

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“…In the simulation model, muscle stimulation is assumed to switch instantaneously between initial and maximal values, as proposed by other investigators (e.g. Levine et al 1983;Zajac et al 1984;Pandy and Zajac 1991). However, as illustrated in Fig.…”

Section: Introductionmentioning

confidence: 99%

Sensitivity of vertical jumping performance to changes in muscle stimulation onset times: a simulation study

Bobbert

Zandwijk

1999

Biological Cybernetics

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The effect of muscle stimulation dynamics on the sensitivity of jumping achievement to variations in timing of muscle stimulation onsets was investigated. Vertical squat jumps were simulated using a forward dynamic model of the human musculoskeletal system. The model calculates the motion of body segments corresponding to STIM(t) of six major muscle groups of the lower extremity, where STIM is muscle stimulation level. For each muscle, STIM was allowed to switch "on" only once. The subsequent rise of STIM to its maximum was described using a sigmoidal curve, the dynamics of which was expressed as rise time (RT). For different values of stimulation RT, the optimal set of onset times was determined using dynamic optimization with height reached by the center of mass as performance criterion. Subsequently, 200 jumps were simulated in which the optimal muscle stimulation onset times were perturbed by adding to each a small number taken from a Gaussian-distributed set of pseudo-random numbers. The distribution of heights achieved in these perturbed jumps was used to quantify the sensitivity of jump height to variations in timing of muscle stimulation onsets. It was found that with increasing RT, the sensitivity of jump height to timing of stimulation onset times decreased. To try and understand this finding, a post-hoc analysis was performed on the perturbed jumps. Jump height was most sensitive to errors in the delay between stimulation onset times of proximal muscles and stimulation onset times of plantar flexors. It is explained how errors in this delay cause aberrations in the configuration of the system, which are regenerative and lead to relatively large jump height deficits. With increasing RT, the initial aberrations due to erroneous timing of muscle stimulation are smaller, and the regeneration is less pronounced. Finally, it is speculated that human subjects decrease or increase RT depending on the relative importance of different performance criteria.

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Dependence of jumping performance on muscle properties when humans use only calf muscles for propulsion

Cited by 35 publications

References 19 publications

Differential effects of countermovement magnitude and volitional effort on vertical jumping

Differential effects of countermovement magnitude and volitional effort on vertical jumping

Sensitivity of a Hill-based muscle model to perturbations in model parameters

Sensitivity of vertical jumping performance to changes in muscle stimulation onset times: a simulation study

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