Acute systemic and energy metabolism responses to velocity-based resistance training following an oral glucose load in individuals with excess body weight.

We investigated the acute metabolic effects of two velocity-based resistance training (RT) protocols, differing in intra-set velocity loss (VL) thresholds, on postprandial substrate oxidation and glycaemic responses following a 75 g oral glucose tolerance test in individuals with excess body weight. A single-group, randomized, cross-over design was used, in which each participant completed three experimental conditions in random order: (1) control (rest); (2) RT with 20% velocity loss (VL20); and (3) RT with 40% velocity loss (VL40). Twenty-four participants (50% female; median body mass index 30.2 kg m-2, interquartile range 27.9-34.1 kg m-2) were included in the final analysis. Each RT session consisted of bilateral leg-press exercises at 55%-65% of one-repetition maximum performed in four sets with 3 min rest intervals, while monitoring repetition velocity. Baseline measurements were performed in the fasted state (1012 h) with participants in the supine position for 30 min, after the oral glucose load at 60 min, and during the experimental conditions at 120, 180, and 240 min. Primary outcomes were respiratory quotient, oxygen uptake, carbon dioxide output, resting energy expenditure and substrate oxidation rates. Secondary outcomes included blood glucose, lactate, heart rate, power output and repetition volume. VL40 elicited greater cardiovascular and metabolic stress, evidenced by elevated heart rate and lactate levels (p < 0.0001). Both RT protocols decreased postprandial respiratory quotient compared with control conditions, with VL40 producing a larger shift towards fat oxidation (time × conditions interaction p < 0.0001). The glucose area under the curve was significantly lower in VL40 than in VL20 or control conditions (p < 0.0001). These findings suggest that velocity-based RT acutely improves postprandial metabolism, with higher VL thresholds conferring superior fat oxidation and glycaemic regulation.