Objectives: Today, participation in physical activities is proposed to improve symptoms of chronic diseases such as osteoarthritis. In this research, we aimed to evaluate the effect of aquatic exercise therapy on the quality of life in women with knee osteoarthritis (KO).

Methods & Materials: Our study used counterbalanced measures design. By random sampling method, 30 females (aged 40 to 74 years) with KO were selected and assigned into 2 experimental groups. The standard questionnaire of “knee injury and osteoarthritis outcome score” (KOOS) was used in 3 time points of pretest, posttest and midtest to measure 5 factors of pain, disease signs and symptoms, daily living activities, sports and functional activities, and quality of life. During the first 8-week (between pretest and midtest), the first group had no training, whilst the second group carried out their own exercise program.
During the second 8-week (between midtest and posttest), the training program of groups got reversed. In other words, both groups used the same training program for 8 weeks, but the training periods were different. The obtained data were statistically analyzed by repeated measures ANOVA using SPSS.

Results: The results of both experimental groups were the same, indicating that: 1) 8 weeks of no training led to no variation in any of 5 dimensions of KOOS, 2) training led to improvement of all dimensions of KOOS, and 3. disruption of training led to lose of achievements. These findings were similar to those obtained by functional tests (P=0.000).

Conclusion: The results showed that the study program is useful for patients with KO and improves their quality of life.