INFLUENCE OF EXERCISE INTENSITY OF MUSCLE OXYGENATION AND ANABOLIC HORMONAL RESPONSE DURING RESISTANCE TRAINING

Abstract

PURPOSE To examine the relationship between training intensity and muscle oxygenation during resistance exercise, and to investigate the effect of muscle ischemia on the anabolic hormonal response to such exercise. METHODS Eleven experienced male weightlifters (20.8 ± 1.3 yr; 96.2 ± 14.4 kg, 182.4 ± 7.3 cm) performed 4 sets of the squat exercise on two separate occasions using either a low intensity (LI) or high intensity (HI) load. During LI subjects performed 15 repetitions for each set with a resistance equal to 60% of their pre-determined one repetition maximum (1RM); during HI they performed 4 repetitions at 90% 1RM. Training intensity for each session was randomly selected, and there was at least 72h between each session. Venous blood samples were obtained from an indwelling cannula before (Pre), immediate post- (IP), 20 minutes post- (20P) and 40 minutes post- (40P) exercise. Near infrared continuous wave spectroscopy was used to measure muscle deoxygenation in the vastus lateralis during exercise. The rate of deoxy Hb/Mb change was used to determine reoxygenation rate. Results No significant differences were seen in the extent of deoxygenation between LI (72.7 ± 18.0%) and HI (79.9 ± 13.4%). However, a delayed reoxygenation period after exercise was significantly different between the two training sessions (35.3 ± 17.4 s vs 24.5 ± 14.3 s in LI and HI, respectively). Testosterone (T) and growth hormone (GH) concentrations were significantly elevated from Pre at IP, 20P and 40P in both LI and HI. GH concentrations were higher (p < 0.05) at LI than for HI at 20P and 40P. CONCLUSIONS Muscle oxygen recovery kinetics appeared to be influenced by training intensity, and delayed reoxygenation appears to affect the GH response to exercise. Supported by NIH Grant HL-44125–12