Bidirectional association of daily steps with sarcopenia: a longitudinal study.

BACKGROUND

Step count is a well-established measure of physical activity, and step-based recommendations offering practical public guidance. However, the bidirectional associations between step count and sarcopenia remain unclear, limiting the application of step-based interventions for sarcopenia prevention. This study examined the directional association between daily steps and sarcopenia.

METHODS

Data were collected from the Xiangya Step Study (a population-based longitudinal study) between January 2020 and December 2022. Average daily steps were tracked via smartphones linked to WeChat, a social networking platform. Sarcopenia was diagnosed using the Asian Workgroup of Sarcopenia 2019 criteria. A two-wave cross-lagged panel model was used to evaluate bidirectional associations between daily steps and sarcopenia. Additionally, logistic regression examines the association between daily steps and incident sarcopenia risk in participants without sarcopenia at baseline. The area under the curve (AUC) was calculated to evaluate the predictive performance of baseline daily steps for incident sarcopenia.

RESULTS

The study included 1,281 participants (30.1% women), averaging 52.1 years. A significant bidirectional association was observed: fewer daily steps at baseline were associated with sarcopenia status one year later (cross-lagged path coefficient [β]=-1.20, 95%CI: -1.90 to -0.50, p = 0.001), and sarcopenia status at baseline was associated with decreased daily steps one year later (β=-0.19, 95%CI: -0.23 to -0.15, p < 0.001). Logistic regression indicated that each standard deviation increase in daily steps was associated with a lower risk of incident sarcopenia (adjusted OR = 0.28, 95%CI: 0.09 to 0.89, p = 0.03). The AUC for daily steps was 0.74 (95%CI: 0.56 to 0.92), with an optimal cutoff of 4,888 steps (sensitivity = 0.62, specificity = 0.85).

CONCLUSIONS

This study highlights a bidirectional inverse association between average daily steps and sarcopenia. Increasing daily steps, especially to 5,000, might help mitigate sarcopenia development. Future research could explore interventions that increase daily steps to prevent sarcopenia and investigate whether sarcopenia reversal could improve physical activity levels.