Cardiometabolic Benefit of Replacing Sedentary Time with Light-Intensity Physical Activity: Compositional Data Analysis of the Nijmegen Exercise Study.

Abstract

Purpose: The cardiometabolic benefits of replacing sedentary time with light-intensity physical activity (LIPA) are unclear. We studied the associations of hypothetically reallocating sedentary time towards LIPA with changes in cardiometabolic risk factors using thigh-worn accelerometery. We also explored whether reallocation effects differed across subgroups with low, moderate, and high sedentary time and compared proportionally similar reallocations to either LIPA or moderate-to-vigorous physical activity (MVPA).

Methods: We assessed physical behaviours across eight consecutive days using thigh-worn accelerometers among adults from the Nijmegen Exercise Study. Multiple cardiometabolic risk factors were assessed and categorised as: 1) anthropometrics, 2) cardiovascular biomarkers, and 3) glucose metabolism. Reallocation effects were estimated for each cardiometabolic risk factor using compositional isotemporal substitution models adjusted for confounders. Analyses were repeated in sedentary time subgroups, i.e. <8.5, 8.5-10, and > 10 hours/day.

Results: We included 1,041 participants (64 (standard deviation 11) years; 39.5% female). Reallocating sedentary time towards LIPA was associated with improvements in anthropometrics, some cardiovascular biomarkers, and glucose metabolism; e.g., replacing 60 minutes/day of sedentary time with LIPA was associated with improvements in BMI (-0.28 (-0.42, -0.13) kg/m 2 ), eGFR (0.68 (0.15, 1.20) mL/min/1.73m 2 ), and glucose (-0.05 (-0.08, -0.03) mmol/L). Trends suggested that reallocation benefits were strongest in those with >8.5 hours/day of sedentary time. Proportionally similar replacements of sedentary time with either LIPA or MVPA were associated with similar cardiometabolic benefits.

Conclusions: Reallocation of sedentary time to LIPA was associated with improvements in cardiometabolic risk factors, predominantly in anthropometrics and glucose metabolism, with greater benefits in the most sedentary individuals. Time reallocation from sedentary time to LIPA may be an effective and arguably feasible strategy to improve population-wide cardiometabolic health.