Short-Term Effects of Blood Flow Restricted Resistance Training in Older Adults at Risk of Mobility Limitations

Abstract

Improvements in muscle strength in older adults have been observed following short-term (6-weeks) high-load (HL) resistance training. Blood flow restricted (BFR) resistance training using low loads has also resulted in strength gains. However, it is unknown whether HL and BFR resistance exercise produce similar effects on hypertrophy and strength gains following short duration training. PURPOSE: To compare lower extremity strength, hypertrophy and functional adaptations to 6-weeks of HL and BFR training in older adults at risk of mobility limitations. METHODS: Twenty-six older adults (76.7 ± 7.8 years; 26.2 ±3.4 kg·m-2) who possessed low knee muscle strength placing them at risk of developing mobility limitations participated in the study. They were randomly assigned to perform twice weekly sessions of HL (70% 1-RM), BFR (30% 1-RM coupled with a vascular restriction of 1.5 times systolic blood pressure at the proximal thigh) or attention control (CON) for six-weeks. HL and BFR groups engaged in three sets of leg extension (LE), leg press (LP), and leg curl resistance training to muscular failure. The CON group performed three sets of light upper body resistance and flexibility training that was not expected to result in muscle adaptations. LE and LP 1-RM, quadriceps cross-sectional area (CSA) via magnetic resonance imaging, and 400 m walking speed were assessed before and after training. RESULTS: There were clear changes in CSA and strength (group x time interaction, P<0.01) in the training groups and there were no changes in the CON group (P>0.05). HL and BFR groups demonstrated a 3% and 4% increase in CSA, respectively (P<0.05). LE 1-RM increased following HL (40%; P<0.01) and BFR (22%; P<0.01) training. LP 1-RM increased 18% and 8% in the HL and BFR groups, respectively (P<0.01). There were no differences in the CSA and strength adaptations between the HL and BFR groups (P>0.05). Walking speed did not significantly change in any group (P>0.05). CONCLUSION: Short-term HL and BFR resistance training show similar improvements in lower extremity muscle strength and CSA in older adults at risk of mobility limitations. This suggests that BFR resistance training may be a viable modality for older adults who are unable to perform HL training. Supported by NIH grant 1R15 A6040700-01A1.