Preliminary Results Of Blood Flow Restriction Training - Musculoskeletal Implications For Astronauts And Healthy Aging

Musculoskeletal (MSK) health declines in astronauts on long-duration missions similar to older sedentary adults. Countermeasures maintaining MSK health include high-intensity resistance training (HIRT). HIRT may be contraindicated for returning astronauts and deconditioned older 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. PURPOSE: Determine effect of BFR LIRT on body composition, strength, functional capacity and aerobic capacity. METHODS: 6 healthy adults (2 females and 4 males), 54.0 ± 17.6 years old with BMI 26.4 ± 1.8 kg/m2 currently participating 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, hand-grip strength (HGS), 1RM in leg and chest press and maximal aerobic power (MAP) on cycle ergometer. Presented results are for first 4-week block of training. 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 (18 ± 3.8 vs. 21.5 ± 2.4 reps, ES = 1.09, p = 0.03), while 1RM improvements were medium in leg press (91.2 ± 17.4 vs. 103.2 ± 17.9 kg, ES = 0.68, p = 0.0001) and small in chest press (65.0 ± 21.2 vs. 74.3 ± 25.6 kg, ES = 0.40, p = 0.02). HGS (82.9 ± 19.6 vs. 83.3 ± 24.6 kg, ES = 0.02, p = 0.45) and MAP (193.3 ± 59.9 vs. 203.3 ± 61.5 W, ES = 0.16, p = 0.04) changes were negligible. Body composition changes were negligible (fat mass: 20.6 ± 7.7 vs. 20.9 ± 8.9 kg, ES = 0.04, p = 0.36; lean mass: 51.1 ± 10.7 vs. 51.7 ± 10.6 kg, ES = 0.05, p = 0.006; BMD: 1.208 ± 0.090 vs. 1.200 ± 0.094 g/cm2, ES = 0.09, p = 0.15). CONCLUSIONS: Preliminary results appear to demonstrate that 4 weeks of BFR LIRT improve functional capacity and upper and lower body strength while preserving aerobic capacity. Supported by: Canadian Space Agency grant