Franchini, E, Cormack, S, and Takito, MY. Effects of high-intensity interval training on Olympic combat sports athletes' performance and physiological adaptation: A systematic review. J Strength Cond Res 33(1): 242-252, 2019 - Combat sports represent around 25% of all Olympic medals disputed, and the success in these sports are determined by technical-tactical excellence and supported by physiological and psychological development. Although the training in combat sports is intermittent training by nature, some researchers have started to focus their attention on the effects of complementary high-intensity interval training (HIIT)-coupled standard combat sports-specific training on morphological, physiological, and performance adaptations. Thus, in this systematic review, we aimed to verify the effects of this type of training on these variables. A total of 117 articles in the electronic databases Pubmed, Scopus, and Web of Science were retrieved, and 9 studies remained in the present systematic review. A total of 228 athletes (138 judo athletes, 40 taekwondo athletes, 18 boxers, 17 karate athletes, and 15 wrestlers) were investigated in these 9 studies (5 with judo athletes, 1 with boxers, 1 with karate athletes, 1 with wrestlers, and 1 with taekwondo athletes). The HIIT protocols investigated did not generate any change in body fat percentage or body mass but generally resulted in increases in max or peak, varying from 4.4 to 23.0%. However, the most observed benefit of HIIT protocols was an increase in anaerobic fitness, represented by improvements in anaerobic power and capacity.