Associations of exercise snacks with sarcopenia and all-cause mortality: A national cohort study

We aimed to examine the associations of exercise snacks (ES), defined as brief accumulated bouts of moderate-to-vigorous physical activity, with sarcopenia and all-cause mortality. We analyzed data from the 2011-2014 National Health and Nutrition Examination Survey (NHANES). Exercise snacks were quantified using two indices: MIMS-ES (average daily MIMS units accumulated during exercise snack bouts) and Time-ES (total daily minutes spent in exercise snack bouts). Survey-weighted regression models, restricted cubic spline (RCS) analyses, and survival analyses were used to examine the associations of exercise snacks with sarcopenia, handgrip strength, and all-cause mortality. Subgroup and sensitivity analyses were conducted to assess the robustness of the results. A total of 2,969 participants were included. In the fully adjusted models, each 1-unit increase in MIMS-ES and each additional minute of Time-ES were associated with 8% and 9% lower odds of sarcopenia, respectively. Higher levels of exercise snacks were also associated with greater handgrip strength. RCS analyses revealed an L-shaped association, with the inverse association levelling off beyond approximately 2,050 units/day for MIMS-ES and 80 min/day for Time-ES. Among participants with sarcopenia, higher exercise snack levels were associated with a lower risk of all-cause mortality, with MIMS-ES (HR=0.83, 95% CI: 0.74, 0.91) and Time-ES (HR=0.80, 95% CI: 0.71, 0.91). The results were broadly consistent across subgroup and sensitivity analyses. These findings suggest that higher levels of exercise snacks were associated with favorable muscle health and survival outcomes, while further prospective and interventional studies are needed to clarify these associations.