12 Weeks Of Blood Flow Restriction Training - Musculoskeletal Implications For Earth And Space

PURPOSE: Musculoskeletal (MSK) health declines in sedentary adults on Earth and astronauts on long-duration missions in space. Countermeasures maintaining MSK health include high-intensity resistance training (HIRT). HIRT may be contraindicated for returning astronauts and sedentary adults due to injury risk. Blood flow restriction (BFR) with low-intensity resistance training (LIRT) is safe and effective in improving muscle mass and strength. Questions remain regarding BFR LIRT effects on other MSK and fitness parameters. Determine effect of BFR LIRT on body composition, strength, functional capacity and aerobic capacity. METHODS: 12 healthy adults (3 females and 9 males), 46.3.0 ± 18.0 years old with BMI 26.0 ± 4.4 kg/m2 participated in 12-week BFR LIRT. Training 3 times per week at 20 - 30 % of 1 repetition maximum (1RM) with 40 - 50 % limb occlusion pressure (LOP) applied to cuffs of training limbs. 2 upper and 2 lower limbs exercises are performed for 4 sets (30 - 15 - 15 - 15) for a total of 75 repetitions per exercise with 30 s rest between sets. Pre and post assessment includes body composition (fat and lean mass and bone mass density (BMD)) through dual x-ray absorptiometry (DXA), 30 s sit to stand test, 1RM in leg and chest press and maximal aerobic power (MAP) on cycle ergometer. Cohen’s d effect sizes (ES) were used to assess magnitude of change and paired sample t-test to calculate level of statistical significance (p < 0.05). RESULTS: 30 s sit to stand improvements were large (23.3 ± 5.0 vs. 31.2 ± 6.5 reps, ES = 1.35, p = 0.02), while 1RM improvements were medium in leg press (85.9 ± 23.0 vs. 102.8 ± 28.8 kg, ES = 0.65, p = 0.04) and small in chest press (81.3 ± 27.4 vs. 95.0 ± 26.4 kg, ES = 0.51, p = 0.01). MAP changes were negligible (202.0 ± 40.2 vs. 201.1 ± 60.9 W, ES = 0.02, p = 0.39) changes were negligible. Body composition changes were negligible (fat mass: 20.2 ± 10.2 vs. 19.1 ± 9.3 kg, ES = 0.11, p = 0.48; lean mass: 52.1 ± 9.4 vs. 51.8 ± 8.9 kg, ES = 0.03, p = 0.23; BMD: 1.208 ± 0.093 vs. 1.197 ± 0.085 g/cm2, ES = 0.12, p = 0.20). CONCLUSIONS: Our results demonstrate that 12 weeks of BFR LIRT improve functional capacity and upper and lower body strength while preserving aerobic capacity. Supported by: Canadian Space Agency