Abstract des Autors

Changes in muscular strength during aging have been a matter of scientific interest since the beginning of this century. It is reasonable to assume that an important part of the changes is due to muscle atrophy. Biopsy samples have shown a net loss in muscle mass and an increasing substitution with fat and connective tissue over 50 years of age, accompanied by an altered fiber type distribution and the preferential atrophy of type II fibers. In this research we aim to appraise, by isokinetic dynamometry, the behaviour of some specific parameters (peak torque as percent of body weight, average power as percent of body weight and torque acceleration energy) in relation to age. We examined 80 male volunteers practising different sports with average level of physical activity, divided in four groups of 20 subjects each, respectively from 20 to 29 years of age, from 30 to 39, from 40 to 49 and from 50 to 59. We evaluated the flexor-extensor muscles of the knee at the commonly tested angular speeds of 60ø/sec, 180ø/sec and 300ø/sec. Subjects included performed a wide range of sports, so that no statistical significance has been reached comparing the results obtained in the different groups. Nevertheless a constant decrease of the average data calculated in the four classes has been noted; this reduction was about 5% for the values of peak torque as percent of body weight and about 7% for the values of average power as percent of body weight and of torque acceleration energy. The analysis of these data confirms that a decrease in maximum anaerobic power performances exists in relation to age, but it results quite moderate when a person continues to exercise some sporting activity even with amateurism. In our opinion it has been useful to compare the power values, average power and torque acceleration energy, besides the values of peak torque that are usually included in the papers; we noticed that the functional data we obtained agree with the bioptic results: the preferential atrophy of type II fibers justifies the higher reduction of the power values compared with the peak torque values. Verf.-Referat