Abstract

The repetition of a specific muscular performance causes a specific adaptation of muscular enzymatic acivities related to the anaerobic glycolytic pathway, the tricarboxylic acid cycle, the mitochondrial electron transfer chain, transamination reactions, and so on. Experimental findings, gathered since the first research by Holloszy and co-workers, show that muscular enzyme adaption to training exhibits many differences according to the different experimental conditions. Some of the factors affecting the modifications induced by endurance training on muscular enzymatic activities related to energy transduction are the following: 1) the time-course of training; 2) the intensity of training; 3) the number of sessions of daily training; 4) detraining and retraining; 5) different types of muscle mitochondria; 7) age and aging of the subjects; 8) sex; 9) drug administration. To study the influence of these factors, rats were trained to run continuously on a rota-road apparatus, at a speed of 25 or 30 metres per minute, for 150 minutes, per day, in one, two or three sessions of daily training. In the gastrocnemius muscle, biochemical assessments were performed after 35, 50, 100, and 150 days training. Which was discontinued 3 days prior to the biochemical tests. The following muscular enzyme acticities were evaluated: 1) for the anaerobic glycolytic pathway: adenylate cyclase, phosphorylase, phosphofructokinase, pyruvate kinase and lactate dehydrogenase; 2) for the tricarboxylic acid cycle: citrate synthase, NAD-dependent isocitrate dehydrogenase, alphaketoglutarate dehydrogenase and succinate dehydrogenase; 3) for the electron transfer chain: cytochrome oxidase; 4) for transamination reactions: alanine aminotransferase and aspartate aminotransferase; 5) for NAD+/NADH exchanges: total NADH-cytochrome C reductase. Verf.-Referat