The repeatability and criterion related validity of the 20 m multistage fitness test as a predictor of maximal oxygen uptake in active young men

Objective: To investigate the repeatability and criterion related validity of the 20 m multistage fitness test (MFT) for predicting maximal oxygen uptake (VO2max) in active young men. Methods: Data were gathered from two phases using 30 subjects ((x) over bar+/-s; age=21.8+/-3.6 years, mass = 76.9+/-10.7 kg, stature = 1.76+/-0.05 m). MFT repeatability was investigated in phase 1 where 21 subjects performed the test twice. The MFT criterion validity to predict VO2max was investigated in phase 2 where 30 subjects performed a continuous incremental laboratory test to volitional exhaustion to determine VO2max and the MFT. Results: Phase 1 showed non-significant bias between the two applications of the MFT ((x) over bar (diff)+/-s(diff)=-0.4+/-1.4 ml kg(-1) min(-1); t=-1.37, p=0.190) with 95% limits of agreement (LoA) +/-2.7 ml kg(-1) min(-1) and heteroscedasticity 0.223 (p = 0.330). Log transformation of these data reduced heteroscedasticity to 0.056 (p=0.808) with bias -0.007+/-0.025 (t=-1.35, p=0.190) and LoA+/-0.049. Antilogs gave a mean bias on the ratio scale of 0.993 and random error (ratio limits) x/divided by 1.050. Phase 2 showed that the MFT significantly underpredicted VO2max ((x) over bar (diff)+/-s(diff)=1.8+/-3.2 ml kg(-1) min(-1); t=3.10, p=0.004). LoA were +/-6.3 ml kg(-1) min(-1) and heteroscedasticity 0.084 (p = 0.658). Log transformation reduced heteroscedasticity to -0.045 (p = 0.814) with LoA+/-0.110. The significant systematic bias was not eliminated ((x) over bar (diff)+/-s(diff)=0.033+/-0.056; t=3.20, p = 0.003). Antilogs gave a mean bias of 1.034 with random error x/divided by 1.116. Conclusions: These findings lend support to previous investigations of the MFT by identifying that in the population assessed it provides results that are repeatable but it routinely underestimates VO2max when compared to laboratory determinations. Unlike previous findings, however, these results show that when applying an arguably more appropriate analysis method, the MFT does not provide valid predictions of VO2max.