A two-minute exercise snack may be sufficient to enhance energy metabolism and fat oxidation in sedentary male college students.

OBJECTIVE: Short-duration exercise snacks are considered a time-efficient strategy for interrupting sedentary behavior, but the metabolic effects of different exercise durations remain unclear. This study compared energy expenditure and substrate oxidation among the 1-, 2-, and 3-min exercise snack protocols during exercise and a 30-min recovery period under a standardized target workload. METHODS: Twenty sedentary male college students completed three exercise snack protocols in a randomized crossover design with a 7-day washout interval between trials. All protocols were performed on a cycle ergometer using a standardized incremental loading scheme (30 W every 10 s to 180 W). The 1-min protocol ended upon reaching 180 W, whereas the 2-min and 3-min protocols maintained this workload until exercise completion. Energy expenditure, fat oxidation, glucose oxidation, and associated physiological indices were continuously monitored during exercise and the 30-min recovery period. RESULTS: All three exercise snack protocols elicited significant acute metabolic responses. During exercise, total fat oxidation was greater in the 2-min than in the 1-min protocol (0.71 ± 0.22 vs. 0.37 ± 0.12 g, p < 0.001), and was not significantly different from that observed in the 3-min protocol (0.71 ± 0.22 vs. 0.78 ± 0.34 g, p = 0.179). During recovery, energy expenditure rate declined in all protocols but followed different trajectories. In the 1-min protocol, it returned to resting level by 25 min (p = 0.095), whereas it remained above resting throughout the 30-min recovery period in the 2-min (1.87 ± 0.21 kcal/min) and 3-min protocols (2.07 ± 0.32 kcal/min; both p < 0.001). Fat oxidation rate increased whereas glucose oxidation rate decreased during recovery. At 30 min of recovery, fat oxidation rate was not significantly different between the 2-min and 3-min protocols (0.15 ± 0.02 vs. 0.17 ± 0.04 g/min, p = 0.068). CONCLUSION: A 2-min exercise snack may be sufficient to increase energy expenditure and fat oxidation while eliciting sustained post-exercise metabolic activation. These findings provide evidence to support the potential application of exercise snacks as a time-efficient exercise strategy for sedentary adults.