EFFECTS OF AEROBIC LONG-DISTANCE RUNNING TRAINING (UP TO 40 KM.DAY(-1)) OF 1-YEAR DURATION ON BLOOD AND ENDOCRINE PARAMETERS OF FEMALE BEAGLE DOGS

The effects of long distance running training on blood parameters, hormone responses and bone growth were studied in young growing dogs. A genetically uniform group of female beagles matched with respect to age and body mass were used. The runner dogs (n=10) underwent gradually increased running exercise up to 40 km-day-1 on a treadmill with 15-degrees uphill gradient 5 days each week during a period of 1 year, while the littermate control dogs (n=10) were kept in their cages throughout the study. Low plasma lactate concentrations of the runners measured immediately after the running training indicated the aerobic metabolism of the dogs while running. Significant decreases of blood haemoglobin concentrations (11%), blood erythrocyte number (10%), and erythrocyte packed cell volume (12%) were found in the runner group. Throughout the experiment, the value of thyroxine was slightly lower (13%) in the runners but no changes were found in tri-iodothyronine, free thyroxine, or cortisol serum concentrations. Serum oestradiol concentration at 56 weeks was significantly lower (42%) in the runner group than in the control group but was not as low (27%) at 70 weeks, Somatomedin-C concentration had decreased significantly by 37% at the age of 56 weeks in the runner group but was again at the level of the control dogs at the end of experiment (at 70 weeks). Ulna and radius bone mass as a ratio to the body mass had significantly increased in the runners. It would seem from our study that long distance running has a positive effect on bone growth. However, inadequate energy intake may have brought about lowered body mass with altered endocrine homeostasis, especially affecting oestradiol and somatomedin-C.