The reliability, validity and usefulness of the 30–15 intermittent fitness test for cardiorespiratory fitness assessment in military personnel

The objectives of this study were to investigate the reliability, validity, and usefulness of the 30–15 intermittent fitness test (30–15(IFT)) in soldiers. The 34 infantry members of the Slovenian armed forces were recruited as participants. Participants performed the continuous incremental treadmill test (TR), a 2-mile run (2(MR)) test, and two 30–15(IFT) tests. Additionally, participants were divided into a highest-scoring group (HSG) and a lowest-scoring group (LSG) based on their scores on the Army Physical Fitness Test. A very high reliability ratings were observed for 30–15(IFT) measures, as follows: end-running speed (ERS) ERS(IFT) (ICC = 0.971)(,) maximal heart rate (HR(max)) HR(maxIFT) (IC = 0.960)(,) and maximal relative oxygen consumption (VO(2max)) VO(2max-IFT) (ICC = 0.975)(.) Although 30–15(IFT) measures demonstrated high correlations (r = 0.695–0.930) to the same measures of TR test, ERS, HR(max) and VO(2max) were higher in the 30–15(IFT) (p > 0.05)(.) Furthermore, ERS(IFT) and predicted VO(2maxIFT) were higher in HSG compared to LSG, whereas HR(max) did not differ. The results of this study show that the 30–15(IFT) test is a reliable, valid and useful tool for assessing cardiorespiratory fitness in the armed forces. Moreover, the ERS and predicted VO(2)max values derived from the 30–15(IFT) could be considered more sensitive markers of combat readiness than the parameters derived from the TR and 2(MR) tests. Trial registration number: NCT05218798.