Comparison of Acute Hormonal Responses between Resistance, Endurance and Endurance-Resistance Exercise in Healthy Young Men

Introduction: This research was aimed at examining acute responses of hormones such as growth hormone (GH), total testosterone (TT), free testosterone (FT), free fatty acid (FFA) and cortisol to resistance (R), endurance (E) and endurance-resistance (ER) exercise. Methods: The participants of this study were 10 healthy young men. R protocol included bench press, lateral pull down, leg extension and leg curl. E protocol comprised of 30 minutes pedaling by cycle ergometer at 70% maximum heart rate. In the ER protocol, the participants first went through the E protocol and after an interval of 15 minutes they performed the R protocol. In the control group they did not do any exercise. Blood samples were collected before, immediately after and 15 minutes after exercise. Results: Results indicated that GH and FT were significantly increased after all 3 protocols (P<0.05). TT and FFA were significantly increased after R and E protocols, respectively (P<0.05). Comparison between groups indicated a significant difference between GH and FT. Cortisol was significantly decreased in the E and ER protocols and the control group (P<0.05) but it did not have a significant decrease in the R protocol. Conclusion: The E and ER protocols can increase GH with lower lactate and cortisol production, while the R protocol provides better anabolic environment for development and hypertrophy of muscle fiber because of higher stress, metabolic and hormonal responses. The increase of FFA after the E protocol was probably the cause of reduction of GH and TT secretion in the ER protocol.