Effect of Progressive Resistance Strength Training on Body Mass Index, Quality of Life and Functional Capacity in Knee Osteoarthritis: A Randomized Controlled Trial

PURPOSE: This study aimed to investigate the effectiveness of progressive resistance strength training of the lower limb rehabilitation protocol (LLRP) on body mass index (BMI), quality of life, and functional capacity in patients with knee osteoarthritis (OA) who were overweight and obese. PATIENTS AND METHODS: Fifty-six patients were allocated into either the Rehabilitation Protocol Group (RPG) or the Control Group (CG) by a computer-generated random number. The patients in the RPG performed the strengthening exercises of the LLRP and followed the instruction of daily care (IDC). The patients in the CG only followed the IDC as a usual care. Gait Speed Test, quality of life, and BMI were taken at pre-test and post-test measurements. Paired samples t-test and two way mixed analysis of variance were used to analyze the change of BMI within and compare the difference of BMI between the groups, respectively. Wilcoxon signed ranked test and Mann–Whitney U-test were used to analyze the changes of quality of life and functional capacity within and compare the differences of quality of life and functional capacity between the groups, respectively. RESULTS: The patients in the RPG reported a significant reduction in BMI (p = 0.025), improvement in quality of life (p ≤ 0.001), and functional capacity (p ≤ 0.001) within group. The patients in the CG also reported a significant improvements in quality of life (p < 0.05). The improvement in quality of life score was greater in the patients with RPG than the CG (p = 0.053). CONCLUSION: The progressive resistance strength training of LLRP is effective in terms of reducing BMI, improving quality of life and functional capacity. TRIAL REGISTRATION: Name: Iranian Registry of Clinical Trials. Number: IRCT20191221045846N3. Enrollment of first participant: 27-07-2020.