Recovery of skeletal muscle contractility and hormonal responses to strength exercise after two weeks of high-volume strength training.

Exercise induced neuromuscular fatigue, recovery and hormonal responses were studied before (R1) and after (R2) 2 weeks of heavy strength training. Seventeen weight-trained male students were recruited into a heavy training group (HT, n = 10) and a control group (n = 7). During heavy training HT exercised leg extensors every day while control group exercised twice a week. Test workouts (R1 and R2) were used to induce neuromuscular fatigue and hormonal responses. Acute fatigue after the test workouts was reduced after heavy training in the HT group (P < 0.05) but not in the control group. Twenty-two hrs after the test workouts recovery from fatigue was not complete before heavy training, but recovery was complete after heavy training in both groups. The relative change in exercise induced cortisol and GH response, from before to after heavy training, was significantly different between groups, but for both hormones alterations in the control groups response was responsible for the between groups difference. IGF-1 concentration was reduced 22 h after the test workout performed after heavy training in the HT group (P < 0.05). In conclusion, two weeks of high volume strength training attenuated neuromuscular fatigue after a test workout with only minor changes in exercised induced hormone response.

Changes in human skeletal muscle contractility and hormone status during 2 weeks of heavy strength training.

To examine neuromuscular and hormone changes during 2 weeks of heavy strength training, 18 weight-trained male students were recruited either into a heavy training group (HT, n = 11) or into a control group (Ctr, n = 7). The heavy training protocol consisted of leg-extensor workouts performed daily, while workouts were performed twice a week in the Ctr group. A test of one repetition maximum (1 RM) was performed before heavy training and on the 2nd day after heavy training. Isokinetic knee extensions, electrical stimulation, and squat jumps were performed before, on the 8th day of heavy training, and on the 4th day after heavy training. Morning blood samples (0800 hours) were drawn before, on the 8th day of heavy training, and on the 4th day after heavy training. Before, and on the 5th day after heavy training, 24 h urine samples were collected. The 1 RM leg press increased by 6 (SEM 2)% in the HT group. Testosterone and insulin-like growth factor-1 concentrations were respectively 12 (SEM 5)% and 11 (SEM 3)% lower than baseline on the 8th day of heavy training; however, hormone levels were back to baseline on the 4th day after heavy training. A significant correlation between individual changes in 1 RM leg press and changes in testosterone concentrations was observed in the HT group (r = 0.69). In the HT group, 24 h urinary catecholamine excretion increased by 26 (SEM 12)%, 3-methylhistidine excretion increased by 21 (SEM 6)% and creatinine excretion increased by 11 (SEM 5)%. There were no significant changes in the Ctr group. This work addresses the role of changes in basal hormone status (morning samples) for skeletal muscle adaptation to heavy strength training.