PREDICTORS OF FAT OXIDATION AND CALORIC EXPENDITURE WITH AND WITHOUT WEIGHTED VEST RUNNING.

This study evaluated the effect of weighted vest running (WVR) on fatty acid oxidation (FAox) and caloric expenditure at predesignated steady-state exercise intensities. Seventeen recreationally trained runners (9 men and 8 women) performed 4 separate graded exercise tests (GXTs) separated by at least 24 hours. The first GXT was a VO₂max test to establish running velocities (percentage of max) at the prespecified exercise intensities (60, 65, 70, 75, and 80% VO₂max). The following randomized WVR trials included a control (no vest), 5% body mass (BM) vest, and 10% BM vest using 3-minute incrementally increasing steady-state stages. Indirect calorimetry was used to measure both FAox (g·min^-1) and caloric expenditure (kcal·min^-1) at each stage. The ANOVA/ANCOVA analysis revealed that intensity had the largest effect on and FAox (p, 0.001) while WVR had a significant main effect on both caloric expenditure and FAox (p, 0.05). Pairwise comparisons revealed that the 10% BM significantly increased caloric expenditure for all exercise intensities compared with control and 5% BM (except 60% VO₂max), while FAox decreased in the 10% BM 70 and 75% VO₂max intensities only. Marginal rsquared (R²_m) demonstrate that when sex + fat-free mass (FFM) + fat mass (FM) were included as covariates, sex was a significant predictor of caloric expenditure but was further explained by the large FFM (kg) differences between the sexes significantly influencing caloric expenditure (R²_m = 0.87, p, 0.001). Exercise intensity, body composition (FFM + FM), and external mass placement are relevant considerations for runners looking to maximize FAox and caloric expenditure. [ABSTRACT FROM AUTHOR]