Effect of the BFR-7211 on lower limb muscle strength in older adults: A randomized controlled trial

Abstract

Objective

To evaluate the efficacy of a proprioceptive neuromuscular facilitation (PNF) stretching program integrated into a massage chair (BFR-7211) on lower limb strength, balance, and functional mobility in older adults, as a potential intervention for preventing sarcopenia and enhancing musculoskeletal health.

Design

A randomized controlled trial with a 4-week follow-up (12 visits) and 1:1 allocation ratio, conducted without blinding due to the nature of the interventions.

Setting and participants

Sixty-two community-dwelling older adults, 65 years and older, from a senior welfare center were randomized into an experimental group (massage chair with PNF stretching) or a control group (standard trunk exercise program) three times per week for a 4-week intervention period.

Methods

The experimental group received mechanical massage therapy utilizing the PNF stretching mode (XM module, level 2) of the massage chair for 20 min, three times weekly over four weeks. The control group performed a standard trunk exercise program consisting of trunk curl-ups, diagonal trunk curls, and single-legged extensions for 30 min per session. The primary outcome was measured by the Short Physical Performance Battery (SPPB). Secondary outcomes included maximal hamstring strength, body composition, depressive symptoms (GDS-K), fear of falling (KFES), and quality of life (K-CASP-16). Adverse events were monitored throughout the study. Outcomes were measured at baseline, 6th visit, and the final visit (visit 12). Within-group changes were assessed using paired t-tests, while between-group differences were analyzed with Welch’s t-tests and a prespecified ANCOVA adjusting for baseline SPPB, age, and sex. Adjusted mean differences with 95% CIs and p-values are reported, and a sensitivity analysis using a linear mixed model accounted for repeated measures at visits 6 and 12 with baseline SPPB as a covariate.

Results

The experimental group showed significant improvements in SPPB total score (from 9.42 ± 2.38 to 11.58 ± 0.67, p < 0.001), chair-stand, balance, and gait speed, while the control group showed minimal or negative changes. Hamstring muscle strength increased significantly in the experimental group for both legs, whereas the control group experienced a decline. The experimental group also demonstrated a slight increase in soft lean mass, which is also statistically significant. The experimental group also demonstrated a significant reduction in fear of falling (KFES: −3.00, p = 0.045) and improved quality of life (K-CASP-16: +2.32, p = 0.032), with no significant change in depressive symptoms or body composition. No serious adverse events were reported.

Conclusion

A four-week massage chair-based PNF stretching program significantly improved lower limb strength, physical function, and perceived health in older adults. This intervention offers a safe, accessible, and effective strategy for enhancing musculoskeletal health and reducing fall risk in older adults.