The Reliability and Validity of the 30-15 Intermittent Field Test with a Ball

The purpose of this study was to determine the reliability and validity of the 30-15 Intermittent Field Test (30-15IFT) with and without a ball and to determine differences across these two methods in female soccer players. Twenty-four collegiate female soccer players participated in this study (19.46 ± 1.22 years; 167.01 ± 7.23 cm; 60.95 ± 7.84 kg). Players performed one trial of the Yo-Yo Intermittent Recovery (YYIR) test, three trials of the 30-15IFT, and three trials of the 30-15IFT with a ball (30-15IFT-B), separated by a minimum of 48 hours. Maximal intermittent running velocity (VIFT), heart rate at exhaustion (HRpeak), and rating of perceived exertion (RPE) were collected. Interclass correlation coefficients (ICCs) demonstrated good reliability during the 30-15IFT in VIFT (ICC = 0.88) and HRpeak (ICC = 0.89), as well as in the 30-15IFT-WB VIFT (ICC = 0.83) and HRpeak (ICC = 0.87). Results showed differences between VIFT, HRpeak, and RPE between trials 30-15IFT and 30-15IFT-B (p \u3c .05). Significant differences were shown in mean VIFT scores between trials 1 and 2 (p \u3c .001) and trials 1 and 3 (p \u3c .001). Estimated maximal oxygen consumption (VO2max) of YYIR and estimated VO2 max of 30-15IFT and 30-15IFT-WB was very strongly (r = 0.82) and strongly (r = 0.68) correlated. In conclusion, the 30-15IFT was deemed valid and reliable and the 30-15IFT-B was reliable in female soccer players