Objectives: To quantify physical activity 32–37 years after acute anterior cruciate ligament injury with respect to the World Health Organization physical activity recommendation, and to compare physical activity levels between: i) individuals managed with anterior cruciate ligament surgery and rehabilitation vs. rehabilitation alone, and ii) individuals with and without symptomatic osteoarthritis. Design: Prospective longitudinal cohort. Methods: Participants (n = 234) within 14 days of anterior cruciate ligament rupture (confirmed arthroscopically) were allocated to early anterior cruciate ligament repair and rehabilitation or rehabilitation alone. Thirty-two to 37 years after anterior cruciate ligament injury, 80 participants provided valid accelerometer data assessing physical activity and underwent an x-ray to assess osteoarthritis. Symptomatic osteoarthritis was defined as radiographic osteoarthritis plus knee pain and/or symptoms. Differences in physical activity parameters between treatment and osteoarthritis groups were assessed with analysis of covariance, adjusted for potential confounding. Results: Tibiofemoral symptomatic osteoarthritis was observed in 35 (47 %) participants (anterior cruciate ligament surgery 44 %; rehabilitation-alone 50 %). Participants spent a mean of 37.1 (95 % confidence interval 31.6–42.6) min/day in moderate to vigorous physical activity. Recommended levels of physical activity (≥ 150 min/week of moderate to vigorous physical activity) were reached by 66 % of participants with tibiofemoral symptomatic osteoarthritis [mean (95 % confidence interval): 35.4 (26.2–44.7) min/day of moderate to vigorous physical activity] and 77 % without tibiofemoral symptomatic osteoarthritis [39.1 (31.5–46.8) min/day moderate to vigorous physical activity]. Adjusted analyses found no differences in physical activity parameters between treatment groups or between participants with or without tibiofemoral symptomatic osteoarthritis. Conclusions: More than 30 years after anterior cruciate ligament injury, over two-thirds of participants reached recommended levels of physical activity. Physical activity levels did not differ based on the initial treatment strategy or presence of tibiofemoral symptomatic osteoarthritis. © 2025 The Authors