Electromechanical delay during knee extensor contractions

Vos, Egbert J.; Harlaar, Jaap; Schenau, G.J. van Ingen

doi:10.1249/00005768-199110000-00013

Cited by 113 publications

(105 citation statements)

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“…A more adequate measure, in our view, is the delay found by cross-correlating a varying input (e.g., rectified EMG) with the corresponding varying force. For leg muscles we found this delay to lie in the order of magnitude of 90-100 ms (Ingen Schenau, Dorssers, et al, 1995;Vos, Harlaar, & Ingen Schenau, 1991). In fact, one of the results presented by Komi and Gollhofer fully supports these arguments.…”

Section: Reflex Contribution In Discrete and Repetitive Movementssupporting

confidence: 82%

Mechanics and Energetics of the Stretch-Shortening Cycle: A Stimulating Discussion

Schenau¹,

Bobbert²,

Haan³

1997

Journal of Applied Biomechanics

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Section: Reflex Contribution In Discrete and Repetitive Movementssupporting

confidence: 82%

Mechanics and Energetics of the Stretch-Shortening Cycle: A Stimulating Discussion

Schenau¹,

Bobbert²,

Haan³

1997

Journal of Applied Biomechanics

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“…It has been reported that isometric knee-extension training at 70% of maximal voluntary contraction reduced electromechanical delay by 18%. 14 If the electromechanical delay is, for example, 100 milliseconds, 15,16 it corresponds to 57° of crank revolution during post 57 ± 6 -7 ± 2 138 ± 26 53 ± 6 -12 ± 2 158 ± 6 73 ± 5 -7 ± 3 101 ± 22…”

Section: Discussionmentioning

confidence: 99%

Cyclists’ Improvement of Pedaling Efficacy and Performance After Heavy Strength Training

Hansen¹,

Rønnestad²,

Vegge³

et al. 2012

International Journal of Sports Physiology and Performance

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The authors tested whether heavy strength training, including hip-flexion exercise, would reduce the extent of the phase in the crank revolution where negative or retarding crank torque occurs. Negative torque normally occurs in the upstroke phase when the leg is lifted by flexing the hip. Eighteen well-trained cyclists either performed 12 wk of heavy strength training in addition to their usual endurance training (E+S; n = 10) or merely continued their usual endurance training during the intervention period (E; n = 8). The strength training consisted of 4 lower body exercises (3 × 4-10 repetition maximum) performed twice a week. E+S enhanced cycling performance by 7%, which was more than in E (P = .02). Performance was determined as average power output in a 5-min all-out trial performed subsequent to 185 min of submaximal cycling. The performance enhancement, which has been reported previously, was here shown to be accompanied by improved pedaling efficacy during the all-out cycling. Thus, E+S shortened the phase where negative crank torque occurs by ~16°, corresponding to ~14%, which was more than in E (P = .002). In conclusion, adding heavy strength training to usual endurance training in well-trained cyclists improves pedaling efficacy during 5-min all-out cycling performed after 185 min of cycling.

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“…To our knowledge, Haan et al (1989) were among the first who applied stimulation protocols that resemble more closely the stimulatio~is as observed for distal leg muscles during running. For instance, if we account for the phase lag between electromyographic signals and force response (associated with but not equal to the rise-time phenomena discussed above; e.g., Inman, Ralston, Saunders, Feinstein, & Wright, 1952;Vos, Harlaar, & Ingen Schenau, 1991), it appears that the triceps surae muscle-tendon complex is not activated until the very last part of the eccentric phase of the muscle-tendon complex (e.g., Hof, 1990;Jacobs et al, 1993). Haan et al (1989) attempted to mimic this situation in SSC contractions of rat gastrocnemius.…”

Section: Efficiency Of Isolated Muscles Reconsideredmentioning

confidence: 99%

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

Schenau¹,

Bobbert²,

Haan³

1997

Journal of Applied Biomechanics

185

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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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Electromechanical delay during knee extensor contractions

Cited by 113 publications

References 0 publications

Mechanics and Energetics of the Stretch-Shortening Cycle: A Stimulating Discussion

Mechanics and Energetics of the Stretch-Shortening Cycle: A Stimulating Discussion

Cyclists’ Improvement of Pedaling Efficacy and Performance After Heavy Strength Training

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

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