The Impact of a High-Intensity Functional Training Program on Athletic Performance of Male Amateur Soccer Players: A Randomized Controlled Study

High-Intensity Functional Training (HIFT) is a popular training modality that aims to improve multiple physical fitness and performance components. This study aimed to examine the effects of HIFT on athletic performance of male amateur soccer players. This randomized controlled study was conducted over a six-week period. Athletes were randomly enrolled into HIFT (n = 12) and control (CON, n = 12) groups. The HIFT group replaced part of the specific training with three weekly sessions of HIFT, whereas the CON group participated only in regular soccer training. Before and after the intervention, athletes were assessed for the 20-m sprint (s), bench press strength (kg), squat strength (kg), average anaerobic power (w), the fatigue index (w/s), the change-of-direction sprint (s), VO_2max (ml/kg/min), soccer specific dribbling track test travel distance (m), and soccer dribble sprint skill (s). The HIFT group showed greater (p ≤ 0.001-0.018, pη² = 0.229-0.584) improvements when compared to the CON group, for the 20-m sprint, bench press, and squat strength, fatigue index, VO_2max, and soccer specific dribbling track test traveled distance. The average anaerobic power approached significance (p = 0.051, pη² = 0.162), but was not significantly different between the groups. HIFT may replace part of regular soccer training to improve athletic performance in amateur soccer players.