During the holy month of Ramadan, Muslims worldwide refrain from eating or drinking from sunrise to sunset over a period of approximately 30 days. Research in adult and youth soccer players has shown that during and/or following Ramadan, performance in athletic and/or skill tests can be affected (Zerguini et al., 2007; Chtourou et al., 2011). Sleep loss (Maughan et al., 2012) and alterations in circadian rhythm can also occur (Drust et al., 2012) potentially affecting preparation, performance and recovery. However, to our knowledge, only one study has examined the effects of Ramadan fasting on athletic performance in match-play conditions in soccer players (Aziz et al., 2018) and no data exist in elite performers. A comparison of 2 simulated matches played by amateur players in both a fasted versus non-fasted state reported a 13% and 35% reduction in total and high-intensity distance covered in the fasted state with a negative impact already noticeable early in the match (Aziz et al., 2018).
In this study, an interesting opportunity arose to investigate running performance in official match-play in a cohort of elite outfield players belonging to a high-standard soccer team (French 3rd division, season 2018-2019) who were observing the Ramadan fast. Ramadan officially began in France on Monday 6th May 2019 and the match kicked-off at 20:45 on Thursday 9th May (result 1-1). As such, the match took place during the early part of Ramadan during which the largest changes in fitness parameters can occur (Maughan et al., 2012). Seven players (age: 26.0 [+ or -] 4.0 years, height: 1.78 [+ or -] 0.07 m, weight: 74.0 [+ or -] 8.3 kg, V[O.sub.2max]: 59.5 [+ or -] 5.2 ml x [kg.sup.-1] x [min.sup.-1]) commenced play in a home League match in a fasted state of which 3 were substituted during the 2nd half. All had performed the Ramadan fast for >8 years. Performance was concomitantly examined in 5 non-fasting peers (age 28.4 [+ or -] 3.9 years, height: 1.81 [+ or -] 0.08 m, weight: 76.8 [+ or -] 8.2 kg, V[O.sub.2max]: 58.0 [+ or -] 4.2 ml x [kg.sup.-1] x [min.sup.-1] of which 3 players completed 90-minutes and 2 entered play as substitutes. Running activity data was unavailable for 1 substitute.
Prior to the match, the cohort had participated in usual low- to moderate-intensity training sessions on the Monday and Tuesday morning (start 10:15, 75-mins duration) and in a low-intensity session on the Wednesday afternoon (start 17:30, 60-mins duration). No information on dietary intake over the course of the week prior to the match was recorded. The habitual 30-min warm-up session was commenced 45-min before the start of the match. Data provided by the French Football Federation showed respective values for temperature and humidity of 13[degrees]C and 62% at the start of play. Darkness fell at 21:17 hours and therefore...