Author(s): PANASCI, M., FERRANDO, V., CASTAGNA, C., MARMONDI, F., RUGGERI, P., FAELLI, E. , Institution: UNIVERSITY OF GENOA, Country: ITALY, Abstract-ID: 1641

INTRODUCTION:
High-Intensity Interval Training (HIIT) has been shown to mitigate performance declines in professional male soccer players during the off-season1. However, its effects in youth female soccer players remain unexplored. This study investigates the impact of a 4-week off-season high-intensity training program on aerobic fitness and sprint endurance in Under-15 female soccer players.
METHODS:
Fifteen U-15 female soccer players from a professional team completed a 4-week training program consisting of two weekly sessions of small-sided games (SSG) consisting of 4 × 4 minutes with 3 minutes of active recovery (running at low intensity) between bouts, and two weekly sessions of repeated sprint training (RST) consisting of 5 reps x 3 sets of 40-m sprint with a 180° change of direction with a rest of 20 seconds between repetitions and 4 minutes between sets. Performance assessments before and after the intervention Yo-Yo intermittent recovery level 1 test (YYIR1) and 30-second test (30s Test) were performed. Aerobic fitness level and sprint endurance ability were assessed though the YYIR1 and 30s Test, respectively. Furthermore, physiological responses were monitored using heart rate (HR) and blood lactate concentration ([La]+) as internal workload indicators, and total distance (TD), moderate speed distance (DMS), high speed distance (DHS), acceleration distance (≥3 m-s-2, DACC) and deceleration distance (≤3 m-s-2, DDEC) as external workload indicators.
RESULTS:
Following the intervention, TD significantly increased in both the YYIR1 (p = 0.000) and the 30s Test (p=0.004, respectively). HR and [La]+ significantly increased only in the YYIR1 (p = 0.001), but not in the 30s Test (p = 0.572). A strong correlation was observed between time spent >85% HRmax and TD in the 30s Test (r = 0.73, p = 0.002). Moreover, a significant correlation between time spent at intensity >85% HRmax and percentage change in TD in the 30s test (r=0.73, p=0.002) was observed. Similar correlations were found between time spent >85% HRmax and TD (r = 0.91, p = 0.000) and percentage change in TD (r = 0.83, p = 0.001) in YYIR1.
Finally, strong correlations were observed between DMS and TD in YYIR1 (r = 0.78, p = 0.001), and DHS and TD in the 30s Test (r = 0.88, p = 0.000).

CONCLUSION:
A 4-week high-intensity off-season training program effectively enhances both aerobic fitness and sprint endurance in U-15 female soccer players. These findings highlight the efficacy of HIIT-based training in mitigating performance losses during the off-season, enabling players to resume the season with improved conditioning.

References:
1) Silva JR, Brito J, Akenhead R, Nassis GP. The Transition Period in Soccer: A Window of Opportunity. Sports Med. 2016; 46(3): 305-13.