Abstract
Introduction: A respiratory exchange ratio peak (RERpeak) of ≥1.10 is widely utilized as a secondary confirmation marker that maximal effort was achieved and a valid graded exercise tests (GXT) was conducted. However, this threshold may not be appropriate for trained runners. This study characterized National Collegiate Athletics Association Division I (n=30; female=14) cross-country runners’ ability to reach the ≥1.10 criterion with respect to both sex and sampling interval (SI) duration.
Methods: Unfiltered RERpeak were determined during the last two minutes of a GXT in sampling intervals of 15-, 30-, and 60-s with strong vocal encouragement.
Results: There were no differences between sexes regardless of SI, but whole cohort RERpeak values were statistically significant (p < 0.05) among all SI (mean ± SEM: RERpeak15 = 1.081 ± 0.007; RERpeak30 = 1.073 ± 0.007; RERpeak60 = 1.065 ± 0.007). Overwhelmingly runners failed to reach an RERpeak ≥1.10 for RERpeak15 (63.3%), RERpeak30 (66.7%) and RERpeak60 (70%). V̇O2peak30 and RERpeak30 were not related for female (r = 0.36; p = 0.21) or male (r = -0.07; p = 0.81) runners.
Conclusions: Either current RERpeak guidelines are not low enough to prevent mass secondary confirmation marker misclassifications or approximately two-thirds of participants terminated their GXT without giving maximal effort. If the former is believed, an RERpeak30 threshold of ≥ 1.03 would have classified all but one participant as having exerted maximal effort. This may be a more suitable cut-off point to confirm GXT validity in high-training volume, competitive female and male runners with V̇O2peaks ≥ ~50 and 60 ml/kg/min, respectively.
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Description
The study evaluates respiratory exchange ratio criteria for trained runners during graded exercise tests.