Efficacy of blood flow-restricted, low-load resistance training in women with risk factors for symptomatic knee osteoarthritis

Segal NA, et al. · PM&R

Isotonic 1RM rose 28.3 ± 4.8 kg with restriction against 15.6 ± 4.5 kg without (p=0.0385), and isokinetic knee-extensor strength scaled to body mass rose 0.07 ± 0.03 Nm/kg with restriction while falling 0.05 ± 0.03 Nm/kg without (p=0.0048). Quadriceps volume on MRI, leg-press power and knee pain did not differ between the arms, so the strength gain arrived without a measurable change in muscle size.

Population

Women over 45 with risk factors for symptomatic knee OA; 45 consented, 40 completed

Intervention

4 weeks of leg-press resistance training at 30% 1RM three times a week, with a cuff progressively restricting femoral blood flow

Comparator

The same 30% 1RM programme without blood flow restriction

Limitations

Four weeks, women only, no symptom or structural endpoint, and an intensive supervised laboratory programme. Participants and assessors were both blinded to allocation, but BMI was lower in the restriction arm at baseline (p=0.0223) and the analysis adjusts for it. The authors note that cuff pressure was not individualised to thigh circumference, which later work recommends, and that whether the same holds in men at risk of knee OA is unstudied. Funded by an American College of Sports Medicine Research Foundation Kaatsu Training Research Grant and two career development awards; the equipment was borrowed, no author took funds from its manufacturer, and the investigators state they retained full independence.