Temporal patterns of fatigue in repeated sprint ability testing in soccer players and acute effects of different IHRs: a comparison between genders

Background: Repeated sprint ability (RSA) in soccer is deemed fundamental to ensure high level of performance. The aim of this study was to investigate the acute effects of two different Initial Heart Rates (IHR) on fatigue when testing RSA in males and females' soccer players and to compare the respective patterns of fatigue. Methods: Nineteen female soccer players (age: 22.5±3.3 years, height 163.9±7.3 cm, body weight 54.3±6.4 kg, BMI 20.6±1.5 kg·m-2) and 15 male soccer players (age: 17.9±1.5 years, height 175.9±5.8 cm, body weight 68.5±9.6 kg, BMI 22.3±1.5 kg·m-2) participated in this study. HRs reached at the end of two different warm-up protocols (~90 vs. ~ 60% HRmax), have been selected and the respective RSA performances were compared, within and between the groups of participants. Two sets of ten shuttle-sprints (15+15 m) with a 1:3 exercise to rest ratio with different IHR% were administered, in different days, in randomized order. To compare the different sprint performances, we employed the calculated Fatigue Index (FI%). Blood lactate concentration (BLa-) was also measured before and after testing, to compare metabolic energy. Results: Significant differences among trials within each set (P<0.01) were found in both genders. Differences between sets were found in male players, (Factorial ANOVA 2x5; P<0.001), not in female. BLa- after warm-up was higher in 90% vs. 60% HRmax (P<0.05), in both genders but at the completion of RSA tests (after 3 minutes) the differences were not significant (P>0.05). Conclusions: difference between genders were found, suggesting specific approach in testing and training RSA in soccer players.