THYROID-HORMONE RESPONSES DURING AN 8-HOUR PERIOD FOLLOWING AEROBIC AND ANAEROBIC EXERCISE

The purpose of this study was to compare the daytime hourly responses of total thyroxine (T-4) and triiodothyronine (T-3) during an 8-hour r ecovery period following aerobic and anaerobic exercise to an equivale nt non-exercise, central period. The data were examined for hourly mea n differences as well as by determination of the integrated area under the curve (AUC) responses. Significant persistent elevations (hourly concentrations and AUC) from control levels in total T-4 following bot h aerobic and anaerobic exercise were found. Total T-3, however, was t ransiently elevated (only in the hourly concentration immediately foll owing exercise) compared with the control following aerobic exercise, but remained unaffected by anaerobic exercise. No significant changes in the total T-3 AUC responses were found due to exercise. The present findings demonstrate that exercise, aerobic and anaerobic, disrupts t he daytime hourly pattern for total T-4 in the blood, but apparently h as minimal effect on total T-3.