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.