To investigate changes and associations between physiological measures (body composition; knee muscular strength) and the six-minute walk test (6MWT) over a 12-week combined therapeutic exercise and nutrition program for patients with knee OA.
Fifty patients with knee OA participated. Assessments were conducted before and after the 12-week program. Participants attended two in-person nutrition counseling sessions (weeks 1 & 6) supplemented by online resources, and 12 in-person exercise sessions (1/week) including instructions for home exercises (twice/week). Body fat percentage, fat and lean mass, isometric knee extension and flexion strength, and the 6-minute walk test (6MWT) were assessed. Analyses included mean changes with 95% confidence intervals (95%CI), standardized response means (SRM), and the association over time between physiological measures and the 6MWT, including interaction terms, using mixed effects regression, reported as β coefficients (95%CI).
Participants (n=50; female=32%; mean age=54.56 ± 6.4; mean BMI=30.11 kg/m2 ± 4.7) experienced improvements in physiological measures. Body fat percentage decreased by 2.07% (95%CI, 1.42 to 2.72). Fat mass decreased by 2.54 kg (95%CI, 1.70 to 3.38). Lean mass increased by 0.54 kg (95%CI, 0.02 to 1.10). Knee flexion strength increased by 8.77 Nm (95%CI, 0.71 to 16.83). Knee extension strength increased by 5.36 Nm (95%CI, 0.92 to 9.80). Performance-based outcome also improved, with a mean increase of 20.32 m in 6MWT distance (95%CI, 5.28 to 35.35). SRMs ranged from 0.3 to 0.9.
Improvements in body composition and strength were associated with better 6MWT performance. A 1% decrease in body fat was associated with a 3.32 m increase in 6MWT (β = 3.32; 95%CI, 1.53 to 5.11). Fat mass reduction (per 1 kg) was associated with a 1.84 m increase in 6MWT (β = 1.84; 95%CI, 0.33 to 3.34). Lean mass gain (per 1 kg) was associated with a 2.19 m increase in 6MWT (β = 2.19; 95%CI, 0.63 to 3.75). Increases in knee extension and flexion strength (per 1 Nm) were associated with 0.52 m and 0.82 m increases in 6MWT, respectively. No interaction effects were detected between body composition and muscle strength over time with 6MWT distance.
Moderate-to-large improvements in physiological measures (SRM = 0.3 to 0.9) and performance-based outcome (SRM = 0.4) are achievable for patients with knee OA completing a 12-week physiotherapy-based exercise and nutrition program. Changes in body composition and muscle strength were associated with functional improvement. Specifically, these results suggest a 5% reduction in body fat percentage is associated with a 16.6 m increase in 6MWT distance, while a 10 Nm increase in knee flexion and extension strength is associated with a 5.2 m and 8.2 m increase in 6MWT distance, respectively. Furthermore, improvements in body composition and knee muscle strength independently contribute to enhanced walking performance.
Combined exercise and nutrition interventions can provide substantial improvements in body composition and muscular strength that contribute independently to improved walking performance.
exercise
nutrition
