medwireNews: Doing regular vigorous exercise is not associated with an elevated long-term risk for developing radiographic knee osteoarthritis (OA) among people at high risk for the disease, suggests an analysis of data from the Osteoarthritis Initiative.
“Although persons with knee symptoms recognize the health benefits of regular physical activity, uncertainty about whether strenuous activity will accelerate joint damage is a common concern,” explain Alison Chang (Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA) and co-researchers.
The study included 1194 individuals at high risk for knee OA but without radiographic evidence of disease at baseline, 13% of whom developed incident radiographic knee OA by the 10-year follow-up. Participants were aged an average of 58.4 years and had a mean BMI of 26.8 kg/m2.
Chang and team categorized participants into four groups based on 8-year participation in strenuous activities such as cycling, running, tennis, swimming, and skiing. Almost half (49.7%) were categorized as persistently doing no exercise, while 29.6% fell into the low category, reporting approximately 1.0 hour/week at baseline that improved to approximately 1.5–2.0 hours/week over the study period. A total of 12.6% were in the moderate and declining group, doing approximately 5.5 hours/week of exercise at baseline with a steady decline to less than 2.0 hours at 8 years, and 8.0% were categorized as having high and improving activity levels, increasing from approximately 7.0 to 8.0 hours/week over the study period.
In all, 15.3% of people who did no exercise throughout the study developed incident knee OA over 10 years, as did 10.7%, 9.3%, and 12.6% of those in the low, moderate, and high groups, respectively.
In unadjusted analyses, the researchers found that people doing any amount or a low-to-moderate amount of vigorous activity over the 8-year period had a significant 34% and 36% lower 10-year risk for incident knee OA, respectively, than those doing none, but there was no significant association between physical activity and knee OA risk after adjustment for age, sex, and BMI.
These results indicate that “even in persons at high risk for [knee] OA, strenuous physical activity is not associated with development of radiographic changes,” write the researchers in JAMA Network Open.
Therefore, “older adults at high risk for knee osteoarthritis may safely engage in strenuous physical activities at a moderate level to improve their general health,” they add.
The team also investigated sitting trajectories among the study participants, finding that 42.5% had a moderate-to-high frequency of extensive sitting (≥4 hours/day on ≥5 days/week) over 8 years. There was no significant association between persistent extensive sitting and radiographic knee OA risk.
Taken together, “[f]indings of the present study suggest that lack of strenuous physical activity participation and frequent extensive sitting are prevalent and appear to be entrenched,” highlighting “the need to incorporate physical activity counseling as part of the standard care for high-risk individuals, at an early stage when physical activity engagement is more attainable,” conclude the study authors.
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