Physical Activity OK For Patients At Risk of Knee Osteoarthritis

Alison Chang, PT, DPT, MS

New analysis findings showed that there was no association between long-term strenuous physical activity participation and incident radiographic knee osteoarthritis.

The findings from Alison Chang, PT, DPT, MS, and colleagues emphasized that older adults who were at high risk for knee osteoarthritis could still engage safely in physical activities at a moderate level to improve their overall health. Chang, from the Department of Physical Therapy and Human Movement Sciences at Northwestern University Feinberg School of Medicine, and the team of investigators analyzed data from the Osteoarthritis Initiative which included men and women with or at an increased risk of developing symptomatic, radiographic knee osteoarthritis.

The investigators recruited community-dwelling adults from 4 US sites and followed them up for <10 years. Participants were eligible if they had high risk for knee osteoarthritis but did not have evidence of radiographic disease in both knees at the baseline visit.

The team estimated weekly hours of engagement in strenuous activities such as jogging, swimming, and cycling over an eight-year follow-up period. The investigators used items from the Physical Activity Scale for the Elderly questionnaire, which assessed activities that older adults commonly engaged in during the previous week. Participants were asked 2 questions: How often they engaged in strenuous sport or recreational activities over the past 7 days and an average of how many hours per day they engaged in such activities.

Chang and the members of the study team used sitting items in the questionnaire to assess extensive sitting behavior over 8 years. They defined extensive sitting as >5 days of sitting activities over the past week and >4 hours per day during those days. Participants answered 2 questions: How often they participated in sitting activities over the past 7 days and how many hours per day did they engage in those activities.

The sample analyzed consisted of 1194 participants with a mean age of 58.4 years old. A majority of the participants were women (58.4%) and the mean BMI was 26.8.

Nearly half (49.7%) of the participants were classified into the persistently no subgroup of 0 hours per week for strenuous physical activity. Almost 30% were in the low, slightly improving subgroup (1-2 hours per week). More than 40% of individuals were in the moderate (32.2%) to high (10.1%) frequency of extensive sitting subgroup.

Among the participants included, 13% developed radiographic knee osteoarthritis by the 10-year follow-up visit. Incidence rates of knee osteoarthritis for the 4 strenuous activities trajectory subgroups were 15.3% (persistently no), 10.7% (low, slightly improving), 9.3% (moderate, declining), and 12.6% (high, improving). For sitting trajectory, the incidence rates were 14% (high frequency), 13.7% (moderate frequency), and 12.4% (low frequency).

Participating in any (unadjusted OR, .66; 95% CI, .47-.93) and in low-to-moderate level strenuous physical activities (unadjusted OR, .64; 95% CI, .44-.91) over 8 years were linked with a reduced likelihood of radiographic knee osteoarthritis over the baseline to 10-year follow-up period compared with those who participated in persistently no strenuous physical activities. High strenuous physical activities compared to persistently no activities was not associated with incident knee osteoarthritis (unadjusted OR, .8; 95% CI, .42-1.52; aOR, 1.07; 95% CI, .55-2.09).

Participants who were older or had a higher BMI were more likely to have a persistent lack of engagement in strenuous physical activities. Such association was the same for those who had more severe knee pain, depression, or weaker quadriceps.

Individuals who were older and at higher risk for knee osteoarthritis may still safely engage in strenuous physical activity at a moderate level.

The study, “Association of Long-term Strenuous Physical Activity and Extensive Sitting With Incident Radiographic Knee Osteoarthritis,” was published online in JAMA Network Open.