Investigation of the physiological and psychological effects of rapid weight loss in combat sport athletes

In combat sports (wrestling, taekwondo, judo), rapid weight loss (RWL) strategies used to achieve weight category compliance can negatively affect both the physical and mental performance of athletes. Fluid restriction during this process may lead to problems such as fatigue, distraction, and increased stress levels. The aim of this study is to examine the effects of RWL in wrestling, taekwondo, and judo athletes by comparatively evaluating physical parameters (body composition, hydration, strength, and vertical jump) assessed through field tests, and mental performance indicators (attention, concentration, beats per minute [BPM], and coherence [COH]) measured with wearable technologies. The study was conducted with a total of 75 competitive athletes aged 13–18, all with at least three years of training experience and regularly participating in training sessions in Çorum, Türkiye. Measurements were carried out at four different time points during the preparation period for the Turkish National Championships (12 weeks, 15 days, 3 days, and the day before weigh-in), and both physical and mental performance data were collected. The findings revealed that athletes experienced up to 5% rapid weight loss prior to competition. Urine Specific Gravity (USG) values indicated severe dehydration, particularly in the measurement taken just before weigh-in. Repeated measures analysis of variance (ANOVA) with Bonferroni-adjusted post-hoc tests demonstrated that declines in physical performance parameters (handgrip strength, back-leg strength, and vertical jump) over time were statistically significant (p < 0.05). Moreover, reductions in attention and concentration, as well as changes in BPM and COH parameters, were found to constitute statistically significant differences reflecting adverse alterations in cognitive functions. In conclusion, RWL was shown to have multidimensional negative effects on young athletes. Therefore, it is recommended to adopt scientifically based, individualized, and sustainable weight management strategies that take into account individual differences.