Effectiveness of aquatic exercise for obese patients with knee osteoarthritis: a randomized controlled trial

Objective: To design an aquatic exercise (AQE) and land-based exercise (LBE) program to enhance knee function and reduce body fat in patients with obesity and knee osteoarthritis and to investigate the effectiveness of AQE and LBE on body fat, functional fitness, and functional status.

Setting: Outpatient clinic at a Seoul National University Bundang Hospital.

Participants: Obese patients with knee osteoarthritis were recruited from patients who visited the rehabilitation, orthopedic surgery, and geriatric outpatient clinics at the hospital. Study participants were limited to those who met the following criteria: body mass index more than 25 kg/m(2), abdominal circumference more than 90 cm (men) or 85 cm (women), clinically diagnosed osteoarthritis with Kellgren-Lawrence scale 2 or higher on radiographic studies, and independent ambulation state.

Methods: Participants were randomly allocated into 3 groups: AQE (n = 26), LBE (n = 25), and the control group (n = 24). Exercise interventions were conducted 3 times a week for 8 weeks.

Outcome measures: Body fat analysis, brief pain inventory, Western Ontario and McMaster Universities' osteoarthritis index, Short Form-36 questionnaire, and knee isokinetic tests were evaluated to assess changes in body fat composition, pain, physical function, and quality of life before and after the exercise program.

Results: Although no significant difference was found in general characteristics among the 3 groups before exercise, body fat proportion in the AQE group decreased significantly (mean +/- SD, from 34.4 +/- 4.7 to 33.3 +/- 4.7; P = .031) after intervention. The body mass index was slightly reduced after intervention, but it was not statistically significant. The AQE group showed significant improvements in pain, disability, and quality of life. Notably, the change in pain interference in the AQE group (mean +/- SD, from 25.8 +/- 15.1 to 18.8 +/- 13.1; P = .009) was greater than that of the LBE group. Both exercise groups showed significant improvements in Western Ontario and McMaster Universities' osteoarthritis index disability compared with the control group.

Conclusions: AQE had an advantage in controlling the interference with activity because of pain. AQE may be an effective tool for patients with obesity who have difficulties with active exercise due to knee osteoarthritis.