Effects Of Body Weight Resistance Training In Hypoxia On Skeletal Muscle Morphology And Function

Abstract

PURPOSE: This study was to determine the effects of body weight resistance training in hypoxia for 8 weeks on the skeletal muscle morphology and function. METHODS: Fourteen college age male students with no resistance training habits were divided into a normobaric hypoxic (FiO2 = 14.5%) training group (H, n = 7) or a normoxic (FiO2 = 20.9%) training group (N, n = 7). They completed resistance training two times per week for 8 weeks (a total of 16 sessions). The resistance training consisted of seven types of whole-body weight resistance training focusing on eccentric muscle contraction. Knee and elbow extension / flection strength (isometric strength, isokinetic strength, and muscular endurance), muscle thickness (rectus femoris and biceps brachii) and circumference (thigh and upper arm) were measured before and after training. During training session, SpO2 (all of sessions) and hart rate were monitored. Also, we measured growth hormone and cortisol at 10 training session. Each parameter was statistical analyzed by Wilcoxon signed rank tests were completed to identify any significant between-groups (p < 0.05). RESULTS: Elbow and Knee isometric and isokinetic strength tended to increase after training in both groups. But there was no significant difference in isometric and isokinetic strength between H and N groups. The % change of total work capacity in knee muscular endurance of H group tended to higher than that of N group. And, the % change of total work capacity in elbow of H group (108.8 ± 10.2%) was significantly higher than that of N group (96.0 ± 8.5%) (P < 0.05). The biceps brachii muscle thickness was significantly increased after training in the H group (110.2 ± 4.7%) compare with the N group (102.6 ± 3.3%) (P < 0.01). Also, rectus femoris muscle thickness, of H group tended to increase in compare with N group. CONCLUSIONS: It was suggested that body weight resistance training in hypoxia for 8 weeks increased muscle strength as well as traditional resistance training and would be improved muscular endurance and promoted muscle hypertrophy.