The study mentioned here was performed to elucidate an evidence-based minimum physical activity threshold to estimate improved or sustained high function for adults with lower-extremity joint symptoms.

A total of 1,629 adults, age ≥49 years with symptomatic lower-extremity joint pain/aching/stiffness were considered for this study. They were participating in the Osteoarthritis Initiative accelerometer monitoring substudy were clinically assessed 2 years apart. Prospective multiside data was collected from these patients. Improved/high function in 2-year gait speed and patient-reported consequences (PROs) were based on improving or remaining in the best (i.e., maintaining high) function quintile as compared to baseline status. Classification trees were used to assess the optimal thresholds predicting improved/high function. These were used for the legacy federal guideline metric which required 150 minutes/week of moderate-vigorous (MV) activity in bouts lasting 10 minutes or more (MV-bout) and other metrics (total MV, sedentary, light intensity activity, nonsedentary minutes/week).

The optimal thresholds based on total MV minutes/week speculated improved/high function outcomes more strongly than the legacy or other investigated metrics. Meeting the 45 total MV minutes/week threshold had elevated relative risk (RR) for improved/high function (gait speed RR 1.8, 95% confidence interval [95% CI] 1.6, 2.1 and PRO physical function RR 1.4, 95% CI 1.3, 1.6) compared to less active adults. Consistent thresholds were observed across sex, body mass index, knee osteoarthritis status, and age.

The results obtained from this study supported a physical activity minimum threshold of 45 total MV minutes/week. These promote improved or sustained high function for adults with lower-extremity joint symptoms. This evidence-based threshold is less rigid than federal guidelines (≥150 MV-bout minutes/week). These provide an intermediate goal towards the federal guideline for adults with lower-extremity symptoms.