Metabolic and hormonal responses to a single session of kumite (free non-contact fight) and kata (highly ritualized fight) in karate athletes

Background: Several studies report martial arts as a good model for investigating neuroendocrine responses to competitive fighting. However, little is known on the metabolic responses elicited by elite athletes during fighting. In particular, the metabolic picture in elite athletes of martial arts is little known. Aim: In the present study, our aim was to investigate the acute effects of a session of karate practice on the glucose-insulin system. Subjects and methods: Ten healthy individuals (6M/4F; BMI: 22.1 ± 0.7 kg/m²; 21.9 ± 1.1 years, mean ± SE) who practice karate in national or international competitions were enrolled. All participants completed two experimental trials in a randomised-crossover fashion. A basal blood sample was collected from each athlete to assess plasma glucose, insulin, cortisol, testosterone and catecholamines, before karate training session. In two separate days, another blood sample was collected from each participants after 3 min of real fighting (kumite) and 3 min of ritualized simulation of combat (kata). Results: In both trials, plasma glucose resulted to be higher at the end the of performance compared to the basal (p <0.001 after kumite and p <0.02 after kata). In contrast, insulin was similar in the basal and after physical activity in the two trials. Catecholamines were higher after kata and kumite sessions with respect to the basal values (p <0.04) and, in particular, epinephrine post-kumite values were much greater than those measured after kata. Conclusions: Our results indicate that unlike performances of karate (kumite and kata) elicit different plasma glucose increases. In particular, we found that glucose and epinephrine concentrations increased more after kumite than after kata.