The Acute Effect of Concurrent Resistance and Repeated Sprint Exercise on Circadian Rhythms of Thyrotropin and Thyroxine in Active Male

Thyroid hormones are essential for normal body growth. So investigating on the acute effects of physical activity on these hormones is of utmost importance. Thus, this study was performed to evaluate the effects of resistance and sprint exercise on the thyrotropin and thyroxine hormones in active men.

Ten volunteers' active males (mean age: 26.1 years, height 176.40 cm, body weight 97.78 kg) participated in two sessions at one-week intervals in resistance (RE) and resistance-repeated sprint (RRSE) exercise programs. The exercise was performed at 4 pm by performing two squat and lift exercises for RE (7 sets of 6 repetitions with 80% maximum repetition) and 6 repetitions of 20 meters speed for RSE. At each session, eight times of blood sampling was implemented at an interval of one hour before the exercise to 20:00 and 24 to 3 at midnight.

Data analysis showed that the effects of RE and PRSE in some hours on the secretion of thyrotropin showed significant differences, but not on thyroxine. The level below the 24-hour curve in comparison to the two sessions of physical activity also showed that the PRSE compared to the RE resulted in the release of more thyrotropin (P=0.0001) and thyroxine (P=0.0001).

It seems that resistance-repeated sprint appears more metabolic needs in the body that may be a way to increase metabolism and loss weight, as well as confirms the need for an adequate recovery period after these combined activities.