Test–retest reliability of the 30–15 Intermittent Fitness Test: A systematic review

PURPOSE: This review aimed to synthesize previous findings on the test–retest reliability of the 30–15 Intermittent Fitness Test (IFT). METHODS: The literature searches were performed in 8 databases. Studies that examined the test–retest reliability of the 30–15 IFT and presented the intraclass correlation coefficient (ICC) and/or the coefficient of variation (CV) for maximal velocity and/or peak heart rate were included. The consensus-based standards for the selection of health measurement instruments (COSMIN) checklist was used for the assessment of the methodological quality of the included studies. RESULTS: Seven studies, with a total of 10 study groups, explored reliability of maximal velocity assessed by the 30–15 IFT. ICCs ranged from 0.80 to 0.99, where 70% of ICCs were ≥0.90. CVs for maximal velocity ranged from 1.5% to 6.0%. Six studies, with a total of 7 study groups, explored reliability of peak heart rate as assessed by the 30–15 IFT. ICCs ranged from 0.90 to 0.97 (i.e., all ICCs were ≥0.90). CVs ranged from 0.6% to 4.8%. All included studies were of excellent methodological quality. CONCLUSION: From the results of this systematic review, it can be concluded that the 30–15 IFT has excellent test–retest reliability for both maximal velocity and peak heart rate. The test may, therefore, be used as a reliable measure of fitness in research and sports practice.