High-Intensity Resistance Training Enhances Strength, But Not Muscle Mass and Physical Functioning Gains During Total Knee Arthroplasty Rehabilitation

Purpose: To determine whether high-intensity resistance exercise training with nutritional support (RET) during recovery from total knee arthroplasty (TKA) induces greater improvements in muscle-related outcomes compared to standard rehabilitation alone (SR). Methods: Thirty-three patients (70±6 y; 28.7±3.1 kg·m -2 ) were randomized to receive RET (intervention+regular rehabilitation, n=18) or SR (regular rehabilitation only, n=15) for 12 weeks, starting 8 weeks post-TKA. RET involved supervised, bilateral, high-intensity resistance exercise, 3x/week, daily supplementation (45g protein, 5.5 g Vivinal® GOS, 800 IU vitamin D, 366 mg calcium), and dietary counselling. Outcomes included bilateral and unilateral leg press 1RM, DXA-derived appendicular lean mass (ALM), CT-derived quadriceps cross-sectional area (CSA), 6-min walking test (6MWT) and 5-times chair-stand test (5CST). Data are mean±SD, analysed with 2-way repeated-measures ANOVAs, or median IQR, analysed with Wilcoxon Signed-Rank test. Results: Bilateral leg press 1RM improved to a greater extent following RET (131±38 to 174±56 kg, P <0.001) vs SR (124±36 to 143±49 kg, P =0.018, P - interaction =0.026). Strength in the non-operated leg increased in the RET group only (RET: 22±17%, P <0.001, SR: 6±11%, P =0.175, P-interaction =0.002). Operated leg strength increased similarly between groups (RET: 51±33%, SR: 40±30%, P-time <0.001, P-interaction =0.338), as did ALM (RET: 0.5±0.8 kg, SR: 0.3±0.8 kg, P - time =0.009, P - interaction =0.390), and quadriceps CSA (operated: RET: 7.8±7.5%, SR: 9.2±5.9%, non-operated: RET: 4.8±4.5%, SR: 3.8±3.7%, P - time <0.001, P-interaction ≥0.557). 6MWT improved more in the SR (428±94 to 513±75 m, P <0.001) vs RET group (417±69 to 460±72 m, P =0.002, P - interaction =0.034). 5CST only improved significantly following RET (RET: 15.3 4.2 to 13.2 3.9 s, P =0.039, SR: 14.4 4.0 to 14.4 5.1 s, P =0.064). Conclusions: Compared to standard TKA rehabilitation, high-intensity resistance training with nutritional support induces greater gains in bilateral strength but not muscle mass or physical functioning.