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) ERSIFT (ICC = 0.971)(,) maximal heart rate (HRmax) HRmaxIFT (IC = 0.960)(,) and maximal relative oxygen consumption (VO2max) VO2max-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, HRmax and VO2max were higher in the 30-15(IFT) (p > 0.05)(.) Furthermore, ERSIFT and predicted VO2maxIFT were higher in HSG compared to LSG, whereas HRmax 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.

Automated summary

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 results showed that the 30-15(IFT) is a reliable and valid tool for assessing cardiorespiratory fitness in soldiers. It demonstrated high reliability ratings for end-running speed, maximal heart rate, and maximal relative oxygen consumption. Additionally, the 30-15(IFT) measures were higher compared to other tests, suggesting that it may be a more sensitive marker for combat readiness.