Daily Hormonal and Neuromuscular Responses to Intensive Strength Training in 1 Week

Abstract

Daily adaptive responses in the neuromuscular and endocrine systems to a 1-week very intensive strength training period with two training sessions per day were investigated in eight elite weight lifters. The morning and the afternoon sessions resulted in acute decreases (P < 0.05-0.01) in maximal isometric strength and in the maximal neural activation (iEMG) of the leg extensor muscles, but the basic levels remained unaltered during the entire training period. Significant (P < 0.05-0.01) acute increases in serum total and free testosterone levels were found during the afternoon sessions. During the 1-week training period, serum total and free testosterone concentrations decreased gradually (P < 0.05-0.001) as observed in the basic morning values before the sessions, but after 1 day of rest serum total and free testosterone reached (P < 0.01 and 0.05) the pre-training level. The sessions resulted also in acute changes (P < 0.05-0.01) in serum Cortisol and somatotropin concentrations, but the basic morning levels did not change during the training period. The present findings suggest that during a short period of intense strength training the changes especially in serum testosterone concentrations indicate the magnitude of physiologic stress of training. The acute changes in serum hormone concentrations during a period of a few days do not, however, necessarily directly imply the changes in performance capacity. A longer period of follow-up lasting a few weeks is probably needed if an individual trainability status of a strength athlete is to be evaluated on the basis of the hormone determinations.

Key words

strength training - serum hormones - training stress