Effects of Resistance Training following change of Exercise Timing in Circadian Rhythm on Male`s Sex Hormone

Journal of Exercise Nutrition & Biochemistry 2010;14(4):205-209.

Abstract

The purpose of this study was to examine the effects of resistance training following change of exercise timing in circadian cycle on male`s sex hormone. The subjects were divided into morning training group(AMG) and afternoon training group(PMG). The subjects were exercised 70% strength of 1 RM and performed training program that change of exercise timing(cAMG, cPMG) for 3 days after resistance exercise during 4 weeks. The change of blood testosterone, LH, cortisol by resistance training during 4 weeks showed no significantly difference between group. However, blood cortisol concentration showed significantly decreased in both cAMG and cPMG as compare with before and after 4 weeks. As shown above, the changes of male`s sex hormone concentration made no significant difference in either AMG or PMG during 4 weeks, but irregular exercise through changes of exercise timing(cAMU cPMG) significantly decreased blood cortisol concentration. Consequently, irregular resistance training against circadian rhythm decreased normal level of blood cortisol secretion in the morning.

Key Words: Circadian rhythm, testosterone, LH, cortisol, resistance training