THE EFFECTS OF AQUATIC WALKING ON SYMPTOMS, FUNCTIONAL LIMITATIONS, AND MUSCLE ACTIVITY IN KNEE OSTEOARTHRITIS

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PURPOSE: To investigate the effects of an underwater treadmill (UT) walking intervention, on knee osteoarthritis (KOA) outcomes in 6 participants with KOA (62.7 ± 14.2 years, Males = 3). METHODS: Activities of daily living (ADLs) was measured through the Knee Outcome Survey (KOS), and muscle activity was evaluated using wireless surface electromyography (sEMG) during a 10-m walk and a 20-cm step-down prior to and following an 8-week (3x/week) UT walking intervention. The UT walking intervention was adapted from the self-paced Arthritis Foundation’s Walk with Ease (WWE) program. Week 1 walking duration was 10 minutes, which increased by 5 minutes each week until a 45-minute duration in Week 8. The KOS for ADLs included two subscales comprised of 6 symptoms and 8 functional limitations. Muscles selected for sEMG analysis included the vastus lateralis (VL), semitendinosus (ST), tibialis anterior (TA), and medial gastrocnemius (MG). Mean muscle activity during the stance phase of walking and while descending a 20 cm step was normalized to a maximal voluntary isometric contraction. Coactivation between the VL-ST and TA-MG was calculated using the normalized mean muscle activity values. Knee flexion excursion was measured via an electronic goniometer. RESULTS: Following the UT walking intervention, KOA symptom outcomes such as stiffness (p = .004), swelling (p = .006), and weakness (p = .02) were reduced significantly and improvements were observed in functional limitations of ADLs such as walking (p = .03); going up stairs (p = .01); going down stairs (p = .02); kneeling on the front of the knee (p = .02); squatting (p = .005); sitting with the knee bent (p = .009). A significant decrease in co-activation of the TA and MG during the 20-cm stepdown was measured (p = .04), and an increase in knee flexion excursion occurred (p = .01). All effect sizes were large (g > .8) CONCLUSIONS: Data obtained in this exploratory study suggests that a UT walking program may lead to improvements in the perception of symptoms and functional limitations. Lastly, the increase in knee flexion excursion during the stance phase of walking and the decrease in muscle co-activation below the knee (TA and MG) while descending a 20 cm step suggests that the UT walking intervention improved factors that contribute to knee stiffness.