Objectives: The purpose of this study was to estimate the effect of optimum jogging in a hot environment on uric acid metabolism.
Methods: Six male subjects performed jogging at each optimum speed. The distance of jogging was 8000 m (400 m track x 20 laps). Each jogging was performed twice, once in the summer season (Sept.) and once in the winter season (March). Blood samples were collected before and at 0, 1, 2, 3, 5 and 24 h after each jogging. Urine was also collected before (after 60 min at rest) and from the onset of jogging until 24 h after.
Results: The wet bulb globe temperature (W.B.G.T.) during jogging ranged from 24.9 to 27.8 degrees C in the summer and from 5.9 to 11.4 degrees C in the winter. There was no difference in the duration of each jogging between summer and winter. However, the heart rate (H.R.) during jogging in the summer was higher than that in the winter. Serum uric acid at each rest ranged from, on average, 6.2 to 6.4 (mg/dl). After jogging in the summer, serum uric acid rose significantly (p < 0.05) and the increase was maintained until 5 h after. Exercise-induced hyperuricemia (above 7.5 mg/dl of serum uric acid) was shown in 3 out of all the subjects. In contrast, serum uric acid in the winter showed no significant change throughout protocol. There was no difference in the change in clearance of uric acid during each protocol between summer and winter. Urinary uric acid excretion at 24 h after, between summer and winter, showed similar levels. The rate of urinary oxypurine excretion (xanthine + hypoxanthine) in summer was higher than that in winter at 1 h and 2 h.
Conclusions: These results suggest that not only jogging but also a hot environment affects uric acid metabolism, especially the increase of purine nucleotide degradation.