Effects of Blood-Flow Restricted Resistance Exercise Versus Neuromuscular Exercise on Mechanical Muscle Function in Adults With Chronic Knee Osteoarthritis-A Secondary Analysis From a Randomized Controlled Trial

Abstract

Knee osteoarthritis (knee OA) is a prevalent condition worldwide. Globally recognized rehabilitation guidelines for knee OA include patient education and neuromuscular exercises (NEMEX). While heavy-load resistance exercise (70%-90% 1RM) often induces pain with knee OA, low-load exercise (20%-40% 1RM) combined with partial blood-flow restriction (BFR-RE) has been introduced without inducing excessive knee joint pain. The present study aimed to compare the effects of NEMEX and BFR-RE on mechanical muscle function in knee OA individuals. Ninety-six participants (age 56.7 ± 7.6; 47 males, 49 females) with symptomatic, radiographic knee OA were randomized to free-flow land-based NEMEX or unilateral machine-based BFR-RE. Both groups exercised biweekly for 12 weeks while also receiving patient education. Outcomes measured from baseline to 12 weeks included maximal isometric knee extensor strength (MVIC), rate of force development (RFD), maximal leg extensor power (LEP), and cross-sectional area (mCSA) of rectus femoris (RF) and vastus lateralis (VL). Significant (p < 0.01) within-group improvements from baseline to 12 weeks were observed in both groups for MVIC (BFR-RE: +0.4 vs. NEMEX: +0.1 Nm/kg), LEP (+0.6 vs. +0.2 W/kg), mCSA for RF (+1.8 vs. +0.6 cm²), and VL (+3.7 vs. +1.0 cm²). BFR-RE led to increases in RFD (+2.11 (50-ms), +4.48 (200-ms) Nm/s/kg) (p < 0.01), whereas NEMEX did not (p > 0.05). Between-group comparisons revealed greater improvements with BFR-RE for all outcomes (p < 0.01). BFR-RE appears superior to NEMEX in enhancing mechanical muscle function and knee extensor mCSA in knee OA individuals. The enhanced physiological responses observed with BFR-RE suggest that this exercise modality should be considered as an adjunct therapeutic tool in future treatment protocols for knee OA patients.

Keywords: blood‐flow restriction; exercise; knee; neuromuscular; osteoarthritis.

FIGURE 1

Within‐ and between‐group changes in percentage related to mechanical muscle function. Group mean %‐changes from baseline to 8 weeks (PRE‐TO‐MID) and baseline to 12 weeks (PRE‐TO‐POST). *p < 0.05 for within‐group change. **p < 0.01 for within‐group change. ^# p < 0.01 for between‐group difference in delta change (Δ). (A) Nottingham LEP: Leg Extensor Power for the symptomatic knee OA leg, Nottingham Power‐Rig; (B) MVIC: Maximal Voluntary Isometric Contraction, KinCom; (C) RFD: Rate of Force Development at 50 ms, KinCom; (D) RFD: Rate of Force Development at 200 ms, KinCom; (E) RF mCSA: Rectus Femoris muscle Cross‐Sectional Area; (F) VL mCSA: Vastus Lateralis muscle Cross‐Sectional Area; BFR‐RE: Blood‐Flow Restricted Resistance Exercise group; NEMEX: NEuroMuscular EXercise group.