The effect of intensive interval training on the anaerobic power of the rat quadriceps muscle.

The effect of intensive interval training on the maximal anaerobic power of the rat quadriceps muscle was investigated. The anaerobic energy production was estimated from the changes in the concentrations of phosphocreatine, adenine nucleotides, inosine monophosphate and lactate in freeze-clamped muscle tissue after electrical stimulation for 2-30 s. The results showed that the maximal running speed of rats tested increased by 24%, the maximal force exerted increased by 13%, and the succinate dehydrogenase activity by 48%, while the adenylate kinase activity was the same before and after training. No difference could be observed between the maximal anaerobic power of the quadriceps muscles of trained and sedentary animals. It seems that trained muscles may be able to work with a higher degree of economy than untrained muscles.