Evaluation of The Acute Hormonal Responses To Concentric, Eccentric And Concentric_ Eccentric Muscle Actions in Healthy Young Men

Evaluation of The Acute Hormonal Responses To Concentric, Eccentric And Concentric_ Eccentric Muscle Actions in Healthy Young Men Introduction: Resistance exercise is a potent stimulus for acute increase in the concentrations of circulating hormones such as Growth Hormone (GH) and Testosterone. Conventional resistance exercise is performed using sequential concentric (CON) and eccentric (ECC) contractions that is performed at a external constant load. The aim of this study, is determining hormonal and metabolic response to CON, ECC and CON-ECC muscle actions in order to develop appropriate resistance exercise protocols and equipment for both athletic populations and patients recovering from injury. In the present study, we have examined the endocrine system responses to six different upper and lower body exercise utilizing the CON, ECC and CON_ECC contractions. Methods: In this study, we examined acute hormonal responses of GH, TT & FT and cortisol of 10 young men who had experienced resistance exercises nonprofessionally. The exercise protocol included six resistance exercise which three of them were upper body and the other three were lower body exercises. The participants performed 3 contraction actions in 3 different days with at least one week interval and at the same time of the day. The exercise protocol included 4 sets in each exercise, every exercise was done 10 repetitions per set, and the resting time between exercises and sets was 90 seconds. CON and ECC actions performed at intensity of 80% CON 10-RM and 80 %( 120% CON 10-RM), respectively. Considering to the counterbalanced force design and on the calculations was done, the intensity of CON-ECC action was 88%CON 10-RM. Blood samples were collected before the exercise, immediately, 15, and 30 minutes after exercise session. Results: In the effect of CON, ECC and CON-ECC contraction actions GH increased, but after CON and CON-ECC trials increased significantly, only. In the effect of three actions, TT & FT increased significantly and following the three actions, cortisol decreased significantly. Conclusion: In despite of existence of significant increase in TT & FT acute response and significant decrease in cortisol response in the effect of CON, ECC and CON-ECC contraction actions, significant difference didn’t observe, that this issue demonstrating that the response of these hormones did not influence by type of contraction action. Also, between acute GH response related to these three actions, observed significant difference that demonstrating GH response depends on type of muscle action and degree of the motor units recruitment besides on intensity and volume of exercise. Key Words: Concentric and Eccentric Contractions, Acute hormone response, Growth Hormone, Total & Free Testosterone, Cortisol.