The effects of selected exercise intensities on skeletal muscle protein degradation.

Abstract

The purpose of this study was to examine the effects of selected exercise intensities on muscle protein degradation. On two occasions eight male trained subjects performed a bench press exercise: on one occasion each set consisted of 10 repetitions at 70% of 1RM; on the other occasion each set consisted of 5 repetitions at 85% of 1RM. Venous blood samples were drawn preceding, immediately following and 24 hours after each exercise sessions and analyzed for 3-methylhistidine and tyrosine. The results showed a significant decrease in the concentration of 3-methyhistidine immediately following exercise. There was a significant decrease in tyrosine following exercise at 85% 1RM when compared to baseline. There was not a significant difference found between the 70 and 85% of 1RM protocols for either 3-methylhistidine or tyrosine. The lack of difference between 70 and 85% of 1RM may have been due to similar motor unit recruitment patterns for the two intensities. The exact mechanisms responsible for decreased protein degradation following strength training exercise are presently unclear but may be the result of mechanical tension placed on the muscle fibre.