Obesity and Osteoarthritis (OA) can affect each other and make a reciprocal causal chain with negative feedback that caused by physical inactivity. Water-based (WB) and land-based (LB) exercises are effective to improve body composition and physical activities. The aim of this study was to compare the effects of both exercise programs on body composition in obese patients with knee OA.

A single-blind randomized controlled trial was done involving 33 men and women aged 40–80 years old with BMI≥25kg/m² and knee OA grade 2 and 3 based on Kellgren-Lawrence grading scale. Subjects were randomly divided into LB (n=18) and WB group (n=15) with aerobic and knee-strengthening exercises for 8 weeks. Body weight (BW), body mass index (BMI), and waist circumference (WC) were measured before and after the program. Data will be analyzed using SPSS 20.0 with independet t test, Wilcoxon and Mann Whitney test if necessary.

Participants who performed the LB exercise program showed significant improvement in BW (mean, 0.22±0.92; P=0.025), BMI (median, 0.36 (0.68–2.88); P=0.040), and WC (mean, 2.13±3.66; P=0.024). While there was no significant improvement of body composition in WB group. However, when both groups were compared, BMI was the only variable that was significantly different (P=0.048), with subjects of LB group showing better result than the WB group.

Land-based exercise program was more effective to improve body composition in obese patients with knee OA due to the effect of gravity that improved muscle strengthening without buoyancy such as in the water. Warm water temperature gives relaxation effect that increases appetite. We suggest longer period of research and greater number of participants to better show a significant improvement for WC and BW variables.