Effect of Ramadan Intermittent Fasting on Swimming Performance

Abstract

During the holy month of Ramadan, Muslims fast (abstain from food and water) from dawn until dusk. In recent years, the proportion of Muslim athletes participating in global athletic events has risen dramatically: roughly 15% since 2010 (Roy, Hwa, Singh, Aziz, & Jin, 2011). As such, it is of particular interest to the sports science community to examine any possible adverse effects of Ramadan style intermittent fasting (RSIF) on athletic performance. This study explored the effects of RSIF on the glucose metabolism, hydration levels, circadian rhythm, and perceived fatigue of 14-16 year-old swimmers. Multiple fitness component tests were conducted in fed and fasted conditions using a within-subject design (n=8). Dehydration was investigated by recording participants’ systolic blood pressure, resting heart rate, and muscular endurance using a sit-up test. Glycogen store depletion was assessed by measuring power through a standing broad jump, and strength using a grip dynamometer. Circadian rhythm disruption was explored using a reaction time device. Finally, perceived fatigue was measured through a self-reported 1-10 OMNI scale. Additionally, participants completed timed maximum effort 400-meter swims. On average, participants completed the 400-meter swim 3.4% slower in the fasted condition than in the fed condition. Moreover, statistical analysis of the fitness component data identified dehydration, sleep disturbance, and perceived fatigue as the primary detrimental factors. Interestingly, perceived fatigue data demonstrated a greater change between fasted and fed conditions compared to any other variable tested. These findings highlight the particular importance of mindset and arousal training for fasting athletes in the future.