Reliability and validity of 30-15 intermittent fitness test for cardiorespiratory fitness assessment among infantry members of Slovenian armed forces: A study protocol

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 VO₂max 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.