Abstract des Autors

Bilateral deficit (BD) is a phenomenon which occurs when during a simultaneous con-traction of both extremities, a single limb produce less force than during a unilateral contraction. The purpose of this study was to determine whether the magnitude of BD might depend upon the stroke/training history of an individual swimmer. 30 swimmers (15 back/front crawlstrokers (group 1); 15 breaststrokers/butterfliers) (group 2) carried out maximal voluntary contractions (unilateral and bilateral) an three transient positions relevant to a stroke motion with a special testing apparatus in laboratory. All contractions were registered and in each force-time curve the maximal amplitude (maximal force) was analysed and later used to calculate the respective BD. To examine the electrical innervation characteristics of a single muscle during unilateral and bilateral contractions the electromyograms (EMG) of the selected muscles of both arms were recorded. The force variables exerted by the swimmers of group 2 were greater during the bilateral task and unilateral task in comparison to group 1. Furthermore, the pattern of EMG in all muscles during the bilateral contractions were different as compared to the unilateral contractions. These differences were greater in group 2 as compared to group 1. It is assumed that the neuromuscular activation during bilateral maximal voluntary contraction is distinctly different from unilateral contraction. We conclude that the BD is of particular interest with respect to the strength training (alternate and/or simultaneous exercises) of the swimmers. Verf.-Referat