We examined the effects of a sustained submaximal isometric contraction on fatigue and recovery rates in untrained prepubescent boys and men. Fifteen prepubescent boys and 15 men executed an isometric plantar flexion at 20% of their maximal voluntary contraction for 10 min. During the fatigue protocol, surface electromyogram of the soleus, medial gastrocnemius, and tibialis anterior muscles were obtained. Following the fatigue protocol, maximal voluntary contraction data were also obtained every 3 min throughout a 15-min recovery period. During the fatigue protocol, agonist and antagonist surface electromyogram increased gradually to a similar extent in both groups. Following fatigue, torque and surface electromyogram during a maximal voluntary contraction decreased compared to pre-fatigue values and recovered in a similar manner in both groups. However, boys showed faster recovery in torque and surface electromyogram during the third minute of recovery period. It is concluded that a low-intensity sustained isometric fatigue protocol induces similar fatigue levels in boys and men. However, there is evidence that boys can recover faster than men.
Georg Thieme Verlag KG Stuttgart New York.