Short-term 16:8 time-restricted feeding increases cardiovascular strain during prolonged endurance running in professional football players

This study examined the effects of a two-week 16:8 time-restricted feeding protocol on exercise-induced heart rate responses in professional football players. Participants assigned to the time-restricted feeding group followed the dietary intervention for two consecutive weeks, and adherence to the protocol was monitored daily through self-reported dietary logs and direct communication with the investigators. Following the intervention, participants completed a standardized 5000 m endurance run with continuous heart rate monitoring. The time-restricted feeding group demonstrated significantly higher heart rate values at all measured time points (8th, 16th, and 24th minute; p < 0.05) compared with controls. Between-group differences were analyzed using independent-samples t-tests. Effect sizes (Cohen's d) and 95% confidence intervals were calculated to facilitate the interpretation of the findings. Significant differences in HR were observed between groups during the endurance test. The TRF group demonstrated significantly higher HR values compared with the NF group at all measured time points and for the average HR across the 24-min exercise period (p < 0.05). Large effect sizes were observed (Cohen's d = 0.84–1.51). These findings suggest that short-term time-restricted feeding was associated with higher heart rate responses during the standardized endurance running task. These results highlight that short-term time-restricted intermittent fasting may influence cardiovascular responses during endurance exercise, even in trained athletes. These results may assist coaches and practitioners in monitoring internal training load when implementing short-term time-restricted feeding protocols in competitive football players.