Effects of physical training on enzymatic activity of human skeletal muscle

Enzymatic activities of GOT, LDH, MDH and CPK were assessed in four normal subjects, before and after a 12 week training period on a cycle ergometer. Determinations were made in muscle at rest and immediately after submaximal and maximal exercise tests and in serum at rest. Muscle biopsies were obtained from the quadriceps by the needle biopsy technique. Maximal oxygen uptake (VO2) increased significantly after training. The after training GOT and MDH muscle resting activities increased significantly. Correlations were found between resting muscle GOT and MDH vs maximal VO2. An increase on resting enzymatic serum activity after training was found for LDH and CPK and a decrease for MDH for the same period. Correlations were found between resting serum and muscle activities of LDH; MDH and LDH serum resting values vs maximal VO2. Finally, it were observed after training increments of muscle activities of GOT and MDH at rest and that these increments correlated adequately with performance. It was also found that muscle GOT activity changes after exercise were modified by training and that it could partly explain serum modifications. Resting serum enzymes levels did not necessarily correlate with muscle levels and these serum levels could be an index of the achieved training.