Int J Sports Med 2004; 25(3): 170-176
DOI: 10.1055/s-2003-45252
Training & Testing

© Georg Thieme Verlag Stuttgart · New York

A Simple Method for Field Measurements of Leg Stiffness in Hopping

G. Dalleau1 , 2 , A. Belli3 , F. Viale1 , 2 , J.-R. Lacour2 , M. Bourdin2
  • 1Centre Universitaire de Recherche en Activités Physiques et Sportives, Faculté des Sciences et Technologies, Université de la Réunion, Le Tampon, France
  • 2Laboratoire de Physiologie de l’Exercice, Faculté de Médecine Lyon-Sud, Université Claude-Bernard, Oullins, France
  • 3Laboratoire de Physiologie - GIP Exercice, Département STAPS, Université de Saint Etienne, France
Further Information

Publication History

Accepted after revision: June 23, 2003

Publication Date:
15 April 2004 (online)

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Abstract

A new method to measure the leg stiffness in hopping and bouncing, with simple technical equipment and under field conditions, is introduced and validated. The leg stiffness (KN) was calculated from only contact and flight times measured by a contact mat. It was compared to the reference stiffness (KR) obtained from force platform measurements. Eight subjects performed, first, submaximal hopping movements at different frequencies (1.8 to 4 Hz, by step 0.2 Hz) and, second, maximal hopping. In sub maximal hopping KN was significantly correlated with KR (r = 0.94; p < 0.001) and the difference between KN and KR ranged from -7.2 % to 6.9 % (at 1.8 and 3.6 Hz respectively) with a limit of agreement of -1.5 kN × m-1. In maximal hopping KN was also related to KR (r = 0.98, p < 0.001) and the inter individual rank order was respected (R = 0.87). It was concluded that the new method could be applied to study extensively intra individual and inter individual variations of leg stiffness in respectively sub maximal and maximal hopping and thus to simplify further investigations in field conditions of the role of stiffness regulation in the optimization of human locomotion.