No link between strenuous physical activity, radiographic knee osteoarthritis
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There was no association between long-term, strenuous physical activity and incident radiographic knee osteoarthritis, according to data published in JAMA Network Open.
“People suffering from knee injuries or [who] had arthroscopic surgical repair of ACL or meniscus are often warned that they are well on the path to developing knee OA,” Alison H. Chang, PT, DPT, MS, of the Northwestern University Feinberg School of Medicine, told Healio Rheumatology.
“They may be concerned that participating in vigorous activities or exercises could cause pain and further tissue damage,” she added. “To mitigate this perceived risk, some have cut down or discontinue strenuous physical activities — such as jogging, cycling, tennis, aerobic exercises, or skiing — although these activities are beneficial to general physical and mental health.”
To analyze whether long-term, strenuous physical activity, as well as extensive sitting, are associated with an increased risk for radiographic knee OA among patients with a high risk for the disease, Chang and colleagues studied data from the Osteoarthritis Initiative (OAI). According to the researchers, the OAI is a prospective longitudinal cohort study of adults with or at an increased risk for symptomatic, radiographic knee OA. In that study, community-dwelling adults were recruited from four sites in Columbus, Ohio; Pawtucket, Rhode Island; Baltimore and Pittsburgh, and followed for up to 10 years.
Chang and colleagues included data from 1,194 participants. All participants demonstrated a baseline Kellgren and Lawrence grade of 0 in both knees, and completed Physical Activity Scale for the Elderly (PASE) questionnaires at baseline as well as during at least two follow-up visits throughout an 8-year interval. Data analyses were performed from May 2018 to November 2018. The researchers used group-based models to identify the baseline-to-8-year trajectories for strenuous physical activity and extensive sitting. The primary outcome was incident radiographic knee OA by the 10-year follow-up visit.
According to the researchers, there were four distinct trajectories of weekly hours spent in strenuous physical activity, and three distinct trajectories of extensive sitting. Long-term low-to-moderate physical activity (adjusted OR = 0.69; 95% CI, 0.48-1.01), or any strenuous physical activity (aOR = 0.75; 95% CI, 0.53-1.07), were not associated with 10-year incident radiographic knee OA. Long-term extensive sitting was also not associated with incident knee OA.
Further, despite participants in this sample demonstrating relatively mild symptoms and high function, 49.7% failed to perform any strenuous physical activities in 8 years, and 42.5% reported persistent moderate-to-high frequency of extensive sitting. Older age, higher BMI, more severe knee pain, non–college-graduate education level, weaker quadriceps and depression were each associated with a persistent lack strenuous physical activity.
“Our study findings convey a reassuring message that adults at high risk for knee osteoarthritis may safely engage in long-term strenuous physical activity at a moderate level to improve their general health and well-being,” Chang said. “Health care providers may consider incorporating physical activity counselling as part of the standard care for high-risk individuals at an early stage when physical activity engagement is more attainable.”
Perspective
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David A. McLain, MD, FACP, FACR
Patients with knee osteoarthritis frequently ask us whether they should exercise or not, particularly if it is strenuous exercise. This study answered this question using the Osteoarthritis Initiative, a prospective longitudinal cohort study of men and women, aged 45 to 79 years at enrollment, at an increased risk of developing symptomatic, radiographic knee OA.
For strenuous exercise, participants were asked via questionnaire, “Over the past 7 days, how often did you engage in strenuous sport and recreational activities such as jogging, swimming, cycling, singles tennis, aerobic dance, skiing (downhill or cross country) or other similar activities?”
For sitting activities, they were asked “Over the past 7 days, how often did you participate in sitting activities, such as reading, watching TV, or doing handicrafts?” Second, “On average, how many hours/days did you engage in these sitting activities?” From these questionnaire answers they were able to get a group-trajectory over the 10 years of strenuous exercise or sitting activities.
Among 1,154 participants, 13% developed radiographic knee OA over the course of the study, and researchers were able to analyze the group trajectories for these participants. The respective radiographic knee OA incidence rates for the 4 strenuous physical activities trajectory subgroups were 15.3% (persistently no), 10.7% (low, slightly improving), 9.3% (moderate, declining) and 12.6% (high, improving). For the 3 extensive sitting trajectory subgroups, the incidence rates were 14.0% (high frequency), 13.7% (moderate frequency) and 12.4% (low frequency).
Compared with no strenuous exercise, any and low-to-moderate strenuous activity was associated with less radiographic knee OA at 10 years. The high frequency of extensive sitting group was associated with older age, higher BMI and more comorbidities. When our patients ask about exercise and knee OA, the answer is “Yes”. This has also been reported in prior studies — stay active and keep moving.
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