european college of sport science

Thursday, June 25th, 2009
THE RATE OF TORQUE DEVELOPMENT OF A BALLISTIC CONTRACTION PRECEDED BY A RAPID ANTAGONIST CON-
TRACTION: EFFECT OF THE CHARACTERISTICS OF THE ANTAGONIST CONTRACTION
RICHARTZ, C., LÉVÉNEZ, M., DUCHATEAU, J.
UNIVERSITÉ LIBRE DE BRUXELLES
The rate of isometric torque development is greater when a rapid (ballistic) contraction is preceded by a rapid contraction of the antagonist
muscles compared with a ballistic contraction performed from a resting condition (Richartz et al., Comput Methods Biomech Biomed
Engin,10 (S1):150-151, 2007). In the current study, we investigated the influence of the torque produced during the antagonist contraction
on the rate of isometric torque development in the subsequent ballistic agonist contraction.
Eleven healthy subjects participated in this investigation. They seated on a chair with their right foot strapped to a footplate. The task
consisted successively: (1) to sustain a submaximal force (20% MVC) with the dorsiflexors, (2) to perform a rapid contraction with the
plantar-flexors (antagonists) and (3) to produce, without transition, a ballistic contraction with the ankle dorsiflexors. The experimental
session was divided into three parts that were executed in a random order: agonist contractions of different torque levels (25%, 50% and
75% MVC) were preceded by an antagonist contraction of 25%, 50% and 75% MVC. We recorded the isometric torque produced by the
plantar- and dorsiflexor muscles and the EMG activities of both agonist (tibialis anterior) and antagonist (soleus and gastrocnemii) muscles
by means of two surface electrodes placed over each muscle.
The results show that the rate of agonist torque development was significantly enhanced with the increase in antagonist torque (AN-
COVA, P