Background/Purpose:  Regular engagement in physical activity reduces the risk adverse health outcomes such as cardiovascular diseases, functional limitation, and depression in people with knee osteoarthritis (OA). While walking is the most common form of physical activity for older adults, the relative health benefits of walking at a light intensity and at a moderate-to-vigorous intensity are unclear. The primary purpose of this study was to investigate the association of replacing ‘no-walking’ with different intensities of walking, with risk of developing adverse health outcomes over two years among people with or at high risk of knee OA.

Methods:  The Multicenter Osteoarthritis Study (MOST) is a NIH-funded longitudinal cohort of older adults who have or are at high risk of knee OA. Steps/day over 7 days were objectively measured with a StepWatch monitor at the 60-month MOST study visit. Walking was classified in minutes per day (min/day) of no-walking (<1 step/minute), very-light walking (1 – 50 steps/min), moderately-light walking (51 – 100 steps/min) and moderate-to-vigorous walking (>100 steps/min). Incident outcomes were slow gait speed during a 20-meter walk (<1 metre/second), comorbidity (Charlson index ≥1), depressive symptoms (CES-D ≥16) and low balance confidence (Activities-specific Balance Confidence scale <67) assessed 2 years post 60-month MOST study visit (i.e., 84-month MOST study visit). Isotemporal substitution analysis was conducted to evaluate the effect of replacing 10 minutes of ‘no-walking’ with 10 minutes of walking at very-light, moderately-light and moderate-to-vigorous intensities, with study outcomes. All models were adjusted for age, sex, BMI, study site, race, education, marital status and lower limb pain.

Results: Of the 1782 subjects who wore the StepWatch for ≥3 days (Age 67.3 ± 7.7, 60% women, BMI 30.7 ± 5.9), incidence of poor health outcomes ranged from 5.6% for depressive symptoms (82/1460) to 16.6% for slow gait speed (251/1514). Replacing 10 minutes of no-walking with 10 minutes of moderate-to-vigorous walking per/day was associated with modest reductions in the risk of slow gate speed and low balance confidence (RR = 0.75 and 0.81, respectively), though low balance confidence bordered on significance (p =.05) (Table 1). Replacing 10 minutes of no-walking with 10 minutes of very-light walking per/day was associated with a small reduction in risk of comorbidity (RR = 0.97).

Conclusion: Findings indicate the presence of a dose-response relationship with regards to walking intensity and pertinent health outcomes in people with, or at high risk of OA. Specifcally, replacing no-walking with just 10 minutes of walking at increasing intensities each day may hold positive consequences for preserving functional gate speed, sustaining confidence with regards to functional capacity (i.e., balance confidence), and reducing risk of comorbidity. Table 1.Adjusted risk ratios

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-association-of-light-and-moderate-to-vigorous-walking-with-incident-poor-health-outcomes-over-two-years-in-people-with-or-at-high-risk-of-knee-osteoarthritis/