Low Morning and Evening Activity Raises Mortality Risk in Knee Osteoarthritis
Daily timing of movement, not just total exercise, may signal long-term health risk in adults with or at risk for knee osteoarthritis.
Adults with or at high risk for knee osteoarthritis who were least active in the morning and evening had about twice the risk of death over eight years, even when overall weekly activity levels were considered.
Study Details
Knee osteoarthritis is one of the most common causes of pain and disability in older adults. While physical activity is known to improve symptoms and overall health, many people with knee OA struggle to meet recommended activity targets. This study explored whether when people move during the day matters, beyond how much they move overall.
Researchers analyzed physical activity patterns across the day to see whether specific timing profiles were linked to long-term survival.
Methodology
The investigators conducted a secondary analysis of an observational cohort study involving 1,927 adults with or at high risk for knee OA across four US clinical sites.
Participants wore hip-mounted accelerometers during waking hours for seven days. Minute-level data were aggregated into hourly activity totals, with careful adjustment for non wear time. Using these data, researchers identified common within-day activity patterns and grouped participants into low, middle, and high expression tertiles for each pattern.
All-cause mortality was tracked for up to eight years. Analyses also examined differences among participants with very low weekly moderate-to-vigorous activity.
Key Findings
Four distinct daily activity patterns explained about 82 percent of overall movement variation.
Lowest morning and evening activity was associated with roughly double the risk of death compared with moderate levels.
Low evening activity alone was also linked to significantly higher mortality risk.
Among those with under 30 minutes of moderate-to-vigorous activity per week, very low morning or morning-evening activity was associated with especially elevated risk.
Eight-year survival was lowest in participants consistently inactive across the day.
Implications for Practice
For patients, these findings suggest that spreading light movement into the morning and evening may matter even if overall exercise capacity is limited. Small, consistent activity during these periods could reflect better resilience and functional health.
For clinicians, within-day activity patterns may offer a practical signal of risk not captured by standard activity totals. Monitoring daily movement timing could help identify patients who appear stable but may have underlying functional decline, opening opportunities for earlier intervention.