Effects of Aquatic Resistance Training on Mobility Limitation and Lower-Limb Impairments After Knee Replacement

Objective: To study the effects of aquatic resistance training on mobility, muscle power, and cross-sectional area. Design: Randomized controlled trial. Setting: Research laboratory and hospital rehabilitation pool. Participants: Population-based sample (N=50) of eligible women and men 55 to 75 years old 4 to 18 months after unilateral knee replacement with no contraindications who were willing to participate in the trial. Interventions: Twelve-week progressive aquatic resistance training (n=26) or no intervention (n=24). Main Outcome Measures: Mobility limitation assessed by walking speed and stair ascending time, and self-reported physical functional difficulty, pain, and stiffness assessed by Western Ontario and McMaster University Osteoarthritis Index (WOMAC) questionnaire. Knee extensor power and knee flexor power assessed isokinetically, and thigh muscle cross-sectional area (CSA) by computed tomography. Results: Compared with the change in the control group, habitual walking speed increased by 9% (P=.005) and stair ascending time decreased by 15% (P=.006) in the aquatic training group. There was no significant difference between the groups in the WOMAC scores. The training increased knee extensor power by 32% (P<.001) in the operated and 10% (P=.001) in the nonoperated leg and knee flexor power by 48% (P=.003) in the operated and 8% (P=.002) in the nonoperated leg compared with controls. The mean increase in thigh muscle CSA of the operated leg was 3% (P=.018) and that of the nonoperated leg 2% (P=.019) after training compared with controls. Conclusions: Progressive aquatic resistance training had favorable effects on mobility limitation by increasing walking speed and decreasing stair ascending time. In addition, training increased lower limb muscle power and muscle CSA. Resistance training in water is a feasible mode of rehabilitation that has wide-ranging positive effects on patients after knee replacement surgery.