High intensity interval training (HIIT) in junior and adult soccer has been shown to improve oxygen uptake (VO2) and enhance soccer performance. The main purpose of the present study was to examine the short term effects of a 5-week HIIT vs. high volume training (HVT) program in 14-year-old soccer players regarding the effects on VO2max and 1000m time (T1000) as well as on sprinting and jumping performance. In a 5-week period, 19 male soccer players with a mean (SD) age of 13.5±0.4 years performed HIIT at close to ~90% of maximal heart rate. HVT intensity was set at 60-75% of maximal heart rate. VO2max increased significantly (7.0%) from pre to post in HIIT but not after HVT. T1000 decreased significantly following HIIT (~-10s vs. ~-5s in HVT). Sprint performance increased significantly in both groups from pre to post testing without any changes in jumping performance.
