COLD-ACCLIMATION AND ENDURANCE TRAINING IN GUINEA-PIGS - CHANGES IN DAILY AND MAXIMAL METABOLISM

The physiological effects of training or cold acclimation on maximal o xygen uptake (VO2,max) and average daily metabolic rate (V-O2,V-dav) o f a small mammal, the guinea pig, are described. Young male guinea pig s were assigned to three experimental groups; control, endurance train ed (70% VO2,max) or cold acclimated (5-7 degrees C) for six weeks. Mea surements of VO2,max and V-O2,V-dav were made before and after the tre atments. V-O2,V-max increased significantly in cold acclimated (+29%) and endurance trained (+23%) animals and was achieved at a higher maxi mal running speed compared to post-treatment controls. Maximal blood l actate concentration was significantly higher in cold acclimated compa red to endurance trained animals. Endurance trained animals had a redu ced V-O2,V-dav compared to control animals, whereas cold acclimation r aised VO2,dav in the cold as expected, but also at room temperature. A ll three groups showed a daily pattern in metabolic rate (night > day) . In conclusion, both endurance training and cold acclimation lead to enhanced V-O2,V-max and changes in resting oxygen consumption througho ut the day.