Is four-week underwater treadmill exercise regimen compared to home exercise efficacious for pain relief and functional improvement in obese patients with knee osteoarthritis? A randomized controlled trial
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Updated: Feb 7, 2026
The Lower Body Positive Pressure Treadmill for Knee Osteoarthritis Rehabilitation
Published on: July 22, 2019
Vilai Kuptniratsaikul1, Chawalit Kittichaikarn2, Phitsanu Suntornpiyapan1
11 Department of Rehabilitation Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
Objective::
To investigate the efficacy of a four-week underwater treadmill exercise regimen compared to a home exercise regimen relative to pain relief and functional improvement in obese patients with knee osteoarthritis.
Design::
Single-blind randomized controlled trial.
Setting::
Outpatient.
Participants::
Eighty primary knee osteoarthritis with pain ⩾5/10 and body mass index ⩾25 kg/m2.
Interventions::
Daily quadriceps exercise at home for 30 minutes (control group) or underwater treadmill exercise (study group) for 30 minutes/day, three times/week for four weeks.
Main Outcomes::
Pain score, six-minute walking distance, quadriceps strength, and body weight were evaluated at baseline and after four weeks. Adverse events, global assessment, and satisfaction index were assessed at the end of study.
Results::
All outcomes in both groups were significantly improved at the end of the study, except for body weight. The mean difference (95% confidence interval (CI)) in outcomes between groups were -0.53 (-1.31, 0.26) for pain; 10.81 (-11.9, 33.53) meters for 6-minute walking distance; 0.67 (-0.10, 1.44) kilograms for quadriceps strength; and 0.01 (-0.66, 0.68) kilograms for body weight. No significant differences were observed between groups, for the per protocol analysis or the intention-to-treat analysis. Participants in the study group evaluated significantly better global improvement and higher patient satisfaction than those in control group (13 (39.4%) vs. 4 (10.8%); P = 0.014 and 23 (69.7%) vs. 16 (43.2%); P = 0.021, respectively).
Conclusion::
Exercise using an underwater treadmill was found to be as efficacious as home exercise for relieving pain and improving function in obese people with mild to moderate knee osteoarthritis.
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