EFFECTS OF ADDITIONAL REPEATED SPRINT TRAINING ON HEART RATE VARIABILITY IN SOCCER PLAYERS DURING THE COMPETITIVE SEASON

Abstract

Heart rate variability (HRV) has become a useful method to screen, monitor and track physical preparedness for optimal performance. Although it has been widely used in sports practice, little is known about its variation following a repeated sprint ability (RSA) training. Therefore, the main purpose of the study was to examine the effects of the RSA on HRV in soccer players. Twenty professional soccer players participated in a 6-week additional repeated sprint training program during the competitive season, which included 1-2 X 6-8 sprints in 25-meter length intervals with a resting period of 25 seconds two times per week. The HRV for each week was calculated using the natural logarithm of the square root of the mean squared difference of successive R-R intervals (LnRMSSD). Over a 6-week period, no significant ‘time’ (F5,120 = 0.348, P = 0.883), ‘group’ (F1,120 = 0.105, P = 0.747) and ‘time*group’ interaction (F5,120 = 0.433, P = 0.825) for LnRMSSD were observed. Based on the group, EXP exhibited more stable LnRMSSD up to week 5, after which LnRMSSD decreased towards the end of the intervention. An increase-decrease pattern of LnRMSSD from week 1 till week 4 for CON was shown, with a plateau reached between week 4 and week 6. RSA training had no significant effect on LnRMSSD in soccer players during the competitive season. Despite a decrease in LnRMSSD in the last week for EXP, the follow-up period of 6 weeks in a competitive period might not be adequately long to obtain more impactful effects on LnRMSSD.