Ramadan intermittent fasting and its association with health-related indices and exercise test performance in athletes and physically active individuals: an overview of systematic reviews.

OBJECTIVE: To systematically review, summarise and appraise findings of published systematic reviews, with/without meta-analyses, examining associations between Ramadan fasting observance (RO), health-related indices and exercise test performances in athletes and physically active individuals. DESIGN: Overview of systematic reviews with assessment of reviews' methodological quality. DATA SOURCES: PubMed, Web of Science, Scopus, Cochrane Database of Systematic Reviews, SPORTDiscus, ProQuest, PsycINFO and SciELO. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Systematic reviews with/without meta-analyses examining associations of RO with health-related indices and exercise performances in athletes and physically active individuals. RESULTS: Fourteen systematic reviews (seven with meta-analyses) of observational studies, with low-to-critically-low methodological quality, were included. Two reviews found associations between RO and decreased sleep duration in athletes and physically active individuals. One review suggested athletes may experience more pronounced reductions in sleep duration than physically active individuals. One review found associations between RO and impaired sleep quality in athletes and physically active individuals. RO was associated with decreased energy, carbohydrate and water intake in adult-aged athletes, but not adolescents. One review suggests RO was associated with athletes' increased feelings of fatigue and decreased vigour. No association was found between RO and athletes' lean mass or haematological indices. RO was unfavourably associated with changes in athletes' performance during high-intensity exercise testing. CONCLUSION: Continuance of training during RO could be associated with athletes' mood state disturbances, decreased sleep duration and performance decline during high-intensity exercise testing, while preserving lean mass. However, careful interpretation is necessary due to the low-to-critically-low methodological quality of the included reviews.