Effects of rapid weight loss on sports performance : A systematic review

Abstract: Aim and research questions: The aim of this study was to investigate the effects of rapid weight loss (RLW) in relation to physiological aspects, psychological aspects, and sport specific performance through a systematic review. This study further aimed to investigate what methods are being used when studying the effects of RWL. To examine the above the following research questions have been used: what physiological and psychological effects can be found in concurrence with RWL, how does the effects of RWL impact sports performance, and what methods are recurrently being used when studying the effects of RWL? Method: For this purpose a systematic review was conducted using three databases; PubMed, Cochrane Library, and SPORTDiscus. Out of 1163 screened articles 20 of them were included in the review. Further analysis was conducted using Forsberg & Wengströms quality evaluation for quantitative studies screening form and the Swedish agency for health technology assessment and assessment of social services Risk of systematic bias screening form. Results were later summarized and compiled. Result: The most evident finding was that the athletes suffer from dehydration with significantly elevated levels of Urine Specific Gravity, USG. In addition the utilization of RWL also have a negative impact on both cognitive functions and mood, it affects important central factors such as reaction time. However many of the negative physiological effects have been show to subside after 4-12 hours if adequate recovery measures are implemented. The foremost evident sport specific finding was a maintained or increased relative anaerobic peak power. Furthermore positive results in maintaining performance for factors such as; Counter Movement-Jump, clean, snatch, judo specific test, and balance test. Conclusion: Although athletes were found dehydrated performance was still maintained in sport specific factors. However, this systematic review also found an overall lack of quality within the studies conducted. Sufficient scientific evidence was not found to draw reliable conclusions, additional studies of higher quality are needed for future reviews.