Effect of K1 Fight on vertical jump, reaction time, and lactate production

Abstract

Introduction: K1 is a combat sport with punches, kicks and knee blows. Two parameters may influence athletes\u2019 performance: injuries (e.g., Zazryn et al., 2003) and fatigue. Some studies were conducted to determine fighters physiological profile such as VO2max (Gosh et al., 1995; Guidetti et al., 2002). However, the effects of fatigue during official K1 fights remain unknown. Therefore, the aim of this study was to determine the effects of fatigue induced by an official K1 fight on vertical jump, simple visual reaction time, lactate accumulation and tactical behaviors. Methods: Eight male volunteers were recruited during regional Italian K1-style amateur competition. Mean (\ub1 SD) age, height, weight and training experience were 24.3 \ub1 1.8 yrs, 173.8 \ub1 5.6 cm, 73.3 \ub1 9.4 kg, 5.6 \ub1 2.2 yrs, respectively. Subjects performed three rounds of 90 s with 60 s rest among rounds. Tests included counter movement jumps, simple visual reaction time (both were measured with an optojump system, Microgate, Italy) and blood lactate (Lactate PRO). They were performed before warm-up and after fights. Vertical jumps and simple visual reaction times were determined 8 minutes after the end of the third round due to judge\u2019s decision and prize giving. Blood lactate was collected 2 minutes after the end of the fight. A complete match-analysis was also made using a camcorder (blow numbers). Results: Match-analysis showed 86 \ub1 23 total blows. No difference was found among rounds. However, punches (39 \ub1 16) and kicks (37 \ub1 16) number during fights was bigger (p<0.001) than knees (10 \ub1 10). While no difference among rounds was found for punches and kicks, knee blows were greater during the third round regarding with the first and second round (+4.8 \ub1 4.1, 2.8 \ub1 3.2, 2.4 \ub1 3.6, respectively, p<0.05). After the end of the fights, blood lactate was found to be on average 15.3 \ub1 1.6 mmol/L. Simple reaction times significant increased (+7.8 \ub1 5.6%; p<0.01) and no difference was found in vertical jump heights. Discussion: Our data showed an altered number of blows among rounds. The increased knee blow number may be due to either or both tactical behaviors and technical economy. High values of blood lactate suggested a key role of anaerobic metabolism in K1 fights. Although high lactate values, vertical jump heights were surprisingly unchanged, this may be due to long rest duration between the end of the fights and post-tests. After the fight, simple visual reaction tim