Muscle power increases after resistance training in growth-hormone-deficient adults

Purpose: To measure the effects of a resistance training (RT) program over muscle function and body composition of adults with GH deficiency without replacement. Methods: 11 GH-deficient patients (39 +/- 11 yr) were evaluated in four occasions (two pretraining and at 6 and 12-wk of training). We performed anthropometric measurements and physical tests. Muscle power was measured by a specific tensiometer (Fitro, Bratislava, Slovakia) in five different exercises: seated chest press, rear lat pull-down, knee extension, standing upright row, and triceps press down. Muscle endurance was assessed by maximum number of sit-ups and maximum static strength by measurement with a handgrip dynamometer. A 12-wk home-based RT program was individually prescribed and consisted of 13 exercises, performed each other day, using simple material. Results: No significant differences occurred in body weight or limb circumferences (P > 0.05), although the sum of central skinfolds decreased with RT (111 +/- 9 vs 100 +/- 9 mm; P < 0.05). RT induced significant gains in four of five exercises: rear lat pull-down (141 +/- 19 vs 198 +/- 20 W), standing upright row (134 22 vs 157 24 W), triceps press down (85 +/- 14 vs 123 +/- 21 W), and seated chest press (114 +/- 20 vs 143 +/- 21 W; P < 0.05). Sit-up results also showed significant improvements, while handgrip did not (P > 0.05). Conclusion: GH-deficient adults without GH replacement may improve their maximum muscle power when submitted to an individualized, simple, and short home-based RT program. Considering that limb girths did not significantly change, the gains were most likely due to improvements in neuromuscular components.