Reliability of a 5-min running field test and its accuracy in V̇O_2max evaluation

Background. Five-min running field test (5_RFT) was established for determining individuals' maximal aerobic velocity (V_max) and functional aerobic capacity (V̇O_2peak) during horizontal run. We determined the number of trials required for establishing high reliability of the 5_RFT and examined its accuracy in evaluating individuals' maximal aerobic capacity (V̇O_2max). Methods. The V_amax(5) recorded during the 5_RFT on four separate days was compared in 45 subjects (14 male, 31 female, 17.0±0.2 yrs) of various levels of physical fitness. The accuracy of V̇O_2max evaluation using V_amax(5) was examined via regression analysis in additional 23 male subjects (20.7±0.3 yrs). Results. The mean correlation coefficient of V_amax(5) among four trials was 0.94. Intraclass reliability coefficient across all trials was 0.98. For trial 3 and 4, the mean value of subjects' V_amax(5) was higher than that of trial 1 and 2. V_amax(5) of trial 2 was also higher than that of trial 1 while no difference was found between trial 3 and 4. F-test of equality of variances demonstrated similar sample variance of V_amax(5) in all trials. Within-subject coefficient of variation in V_amax(5) was 3.7% for all trials was reduced to 2.4% for trial 3 vs 4. For examining the accuracy in V̇O_2max evaluation, regression analysis revealed that the V_amax(5) explained 35.0% of the variance of measured V̇O_2max (SEE = 5.64 ml · kg^-1 · min^-1). Conclusions. The 5_RFT is reliable in determining V_amax(5). Nevertheless, two familiarization sessions are recommended for achieving the best performance in the test. The 5_RFT cannot evaluate V̇O_2max with reasonable accuracy in young males.