Reliability and Validity of the 30–15 Intermittent Field Test With and Without a Soccer Ball

Objective: The purpose of this study was to examine the reliability and validity of the 30–15 Intermittent Field Test (30–15IFT) with and without a ball. Methods: Twenty-four collegiate female soccer players (19.46 ± 1.22 years; 167.01 ± 7.23 cm; 60.95 ± 7.84 kg) performed 1 trial of the Yo-Yo Intermittent Recovery (YYIR) test, 3 trials of the 30–15IFT, and 3 trials of the 30–15IFT with a ball (30–15IFT-B), separated by a minimum 48 hours. Maximal intermittent running velocity (VIFT), heart rate at exhaustion (HRpeak), and rating of perceived exertion (RPE) were collected. Results: Intraclass correlation coefficients (ICCs) between trials demonstrated good reliability during the 30–15IFT in VIFT (ICC = 0.88) and HRpeak (ICC = 0.89), in addition to the 30–15IFT-B VIFT (ICC = 0.83) and HRpeak (ICC = 0.87). VIFT was significantly reduced in 30–15IFT-B (15.82 km h−1) compared to 30–15IFT (17.52 km h−1; p < .001), regardless of trial. HR and RPE were significantly greater in 30–15IFT compared to 30–15IFT-B (p < .05). Estimated maximal oxygen consumption (VO2max) YYIR and estimated VO2max of 30–15IFT and 30–15IFT-B was very strongly (r = 0.82) and strongly (r = 0.68) correlated. Conclusion: The 30–15IFT is considered valid and reliable and the 30–15IFT-B was reliable in female soccer players.