The purpose of this study was to examine exercise ability after discontinuing physical exercise for long periods. The Wistar strain rats were devided into three groups, consisting of sedentary control (C), endurance exercise for 20 weeks (CT), and training discontinuation for 8 weeks (ST) after continuous exercise for 12 weeks. Arterial and venous blood samples and biochemical substances from the heart, liver, and muscles were analyzed immediately after acute exercises. A decrease of blood glucose induced by exercise was shown in ST, and blood lactate was significantly elevated in ST in comparison with CT. The concentrations of tissue glycogen of ST and CT were not significantly different. The level of lactate content was tented to increase in some tissues, especially in the muscles of SOL and EDL from ST. In the SOL muscle, the enzyme capacities of CK, LDH, SDH, and MDH were increased in CT, ST, and C, in descending order. Significant differences in SDH and MDH activities were seen in C as well as CT in comparison to ST. On the other hand, the enzyme capacities from EDL muscle did not alter with exercise in comparison to those of SOL. We speculate that these negative effects on biochemical substrates produced by acute heavy exercise after training discontinuation for 8 weeks might be greater than that of the continuous exercise group. Therefore, it is necessary to consider exercise ability without overestimating of the former training capacity when re-training is begun in the future.

DESCENTE SPORTS SCIENCE Vol.10/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE