MUSCLE FATIGUE IN A STANDING HEEL-RISE TEST

The fatigue process of the triceps surae was evaluated during a standi ng heel-rise test, comprising of eccentric and concentric muscle actio ns, Ten healthy women with a mean age of 24 years participated. The he el-rise test was performed until exhaustion, Work and electromyographi c activity expressed as root mean square and mean power frequency of t he gastrocnemius and soleus muscles were calculated. The average numbe r of heel-rises performed was 25 +/- 1. Work decreased significantly d uring the test. Mean power frequency decreased significantly in both p hases, During the eccentric phase the decrease was significantly large r in the gastrocnemius than in the soleus muscle. There were no signif icant changes in root mean square except for a decrease in the soleus muscle during the eccentric phase. The present results, showing differ ent fatigue patterns in the two muscles, could be used as reference wh en testing the fatigue process in different clinical conditions. Recom mendations for standardization of a heel-rise test are given.