Exercise and recovery responses of adrenal medullary neurohormones to heavy resistance exercise

Purpose: The purpose of this study vas to examine the effect of dynamic res istance exercise on the response patterns of adrenal medullary neurohormone s in strength-trained men. Methods: Ten strength-trained men (21.7 +/- 0.58 yr) gave informed consent and performed two resistance exercise protocols, high force and high power, of equal total work in a randomized order separ ated by 1 wk. Blood samples were obtained pre-exercise (baseline), 0 (R-0), 15 (R-15), and 240 (R-240) min postexercise and under resting control cond itions for each time point. Results: There were no significant differences in control concentrations for each time point and no difference in pre-exer cise values between the two resistance exercise protocols for plasma lactat e, epinephrine, plasma peptide F (P-F), or norepinephrine (NE). Plasma lact ate significantly (P less than or equal to 0.05) increased from baseline fo r both protocols; however, concentrations were higher in response to the hi gh force protocol. Plasma epinephrine was significantly increased from base line at R-0 and returned to baseline at R-15 for both protocols. In contras t, plasma P-F was significantly decreased at R-0 from baseline; however, at R-240 P-F had significantly increased to >80% baseline for both protocols. Conclusions: These results indicate that the adrenal medulla was activated in response to the acute stress of both types of heavy resistance exercise . Furthermore, during longer recovery periods, the adrenal medulla was also active above baseline conditions as increased concentrations of proenkepha lin fragments (i.e., P-F) were detected in the circulation.