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The effects of negative work on the maximal instantaneous muscular power of humans during vertical jumps

Atchou, Guillaume ; Azabji, Marcel ; Moia, Christian ; Ferretti, Guido

In: Sport Sciences for Health, 2015, vol. 11, no. 3, p. 243-249

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    Titre
    • The effects of negative work on the maximal instantaneous muscular power of humans during vertical jumps
    Auteur
    • Atchou, Guillaume. Faculté de Médecine et des Sciences Biomédicales, Yaoundé, Cameroun
    • Azabji, Marcel. Faculté de Médecine et des Sciences Biomédicales, Yaoundé, Cameroun
    • Moia, Christian. Département APSI, Université de Genève, 1 rue Michel Servet, CH-1211, Genève 4, Switzerland
    • Ferretti, Guido. Département APSI, Université de Genève, 1 rue Michel Servet, CH-1211, Genève 4, Switzerland
    Type de document
    • Postprint
    Identifiant OAI-PMH
    • oai:doc.rero.ch:331991
    Summary
    The aim of this study was to test the hypothesis that the maximal instantaneous muscular power of humans ( $$ \dot{w} $$ w ˙ p) is affected by the negative work performed immediately before the jump (w n), possibly due to the recoil of elastic strain energy stored in previously stretched series-elastic elements of the muscle-tendon complex. Twenty-seven Bantu subjects (age 25.1±4.3years, body mass 67.5±7.8kg) were investigated. The $$ \dot{w} $$ w ˙ p, the average power ( $$ \dot{w} $$ w ˙ a) and w n were determined during maximal vertical jumps off both feet on a force platform. Three jumping conditions were studied: squat jumps (SQ), countermovement jumps (CM), and jumps preceded by a free fall (FF) from a height of 0.3m above the platform surface. The w n was higher in CM than in SQ and in FF than in CM and SQ. The $$ \dot{w} $$ w ˙ p was 3.51±0.54kW in SQ and did not vary in CM and FF. The $$ \dot{w} $$ w ˙ a increased with increasing w n (1.70±0.30; 1.85±0.34; 1.99±0.31kW in SQ, CM and FF, respectively, p<0.05). The greater was the w n, the higher was the force at the start of the positive push phase, and thus the maximal force attained during the push phase. In conclusion, $$ \dot{w} $$ w ˙ p was independent of w n, whereas $$ \dot{w} $$ w ˙ a was affected, because a greater force was developed over a shorter time during the push. The independence of $$ \dot{w} $$ w ˙ p of w n leads to refutation of the tested hypothesis.