Dose-response association between daily step count and health-related outcomes in older adults: a nationwide cross-sectional study in Thailand.

BACKGROUND

Daily step count has emerged as a practical and objective metric of physical activity. However, evidence linking step volume to multidimensional health-related outcomes in Asian older adults remains limited. This study aimed to examine the dose-response associations between objectively measured daily step counts and quality of life, knee-specific functional outcomes, and physical performance in community-dwelling older adults, and to identify clinically meaningful step count thresholds.

METHODS

This nationwide cross-sectional study included 2,603 Thai adults aged ≥ 60 years recruited using multi-stage probability sampling. Daily step counts were measured using wrist-worn accelerometers over 7 days and categorized into six groups (≤ 3,000 to > 15,000 steps/day). Outcomes included EuroQol 5-Dimension 5-Level (EQ-5D-5 L) utility, EuroQol Visual Analogue Scale (EQ-VAS), Knee Injury and Osteoarthritis Outcome Score (KOOS), Oxford Knee Score (OKS), Timed Up and Go test (TUG), Five Times Sit-to-Stand test (5×STS), gait speed, and leg strength. Multivariable linear regression models adjusted for age, sex, BMI, comorbidity, knee osteoarthritis, and geographic region were used to evaluate independent associations.

RESULTS

The mean daily step count was 9,488 ± 5,639 steps per day. All eight outcomes demonstrated significant monotonic dose-response relationships across step count groups (p < 0.001 for trend). After full adjustment, the highest step count group (> 15,000 steps/day) had significantly better outcomes than the lowest (≤ 3,000 steps/day), including shorter TUG time (- 3.7 s), faster gait speed (+ 0.20 m/s), higher KOOS (+ 9.5 points), and higher EQ-5D-5 L utility (+ 0.087) (all p < 0.001), with several differences exceeding established minimal clinically important thresholds. Associations were most pronounced among participants aged > 75 years.

CONCLUSIONS

Higher daily step counts are independently associated with better quality of life, knee-specific function, and physical performance among community-dwelling Thai older adults. A target of 6,000-9,000 steps per day appears clinically meaningful and pragmatically attainable. Daily step count may serve as a practical and scalable metric to guide healthy aging strategies in Asian populations.