The effect of upper body resistance training with different intensities on the testosterone to cortisol ratio in untrained men

The appropriate and optimal intensities of resistance exercise to develop muscle strength are of particular importance. The purpose of the current study was to examine the effects of chronic upper body resistance exercise with different intensities on the testosterone to cortisol (T/C) ratio in untrained men. To this end, fifteen healthy sedentary male volunteers (age: 18.5±1.2 yrs, weight: 66.3±7.3 kg and BMI: 23.6±2.7 kg.m-2) were submitted to upper body resistance exercise for an experimental period of 8 weeks. The experimental phase started with an initial 3 weeks of exercises with 50% of 1RM (low intensity), continued with 3 weeks of exercises with 70% of 1RM (moderate intensity), and ended with 3 weeks of exercises with 90% of 1RM (high intensity). Blood samples were collected before (baseline) and 48 hrs post exercise in the third, sixth and eighth weeks of training protocol. Serum levels of testosterone and cortisol were determined by CLIA and RIA, respectively. One-way analysis of variance with repeated measures was used for data analysis. Results showed that upper body resistance training of different intensities resulted in significantly different T/C ratios in sedentary men (P = 0.001). T/C ratio was significantly altered after moderate intensity resistance exercise compared to the baseline (P = 0.001). Also, significant differences were observed in T/C ratio between moderate and high intensity exercise protocols (P = 0.001). In conclusion, high intensity upper body resistance exercise training might induce a hormonal condition favorable to the protein metabolism.