Reference values for and cross-validation of time to exhaustion on a modified Balke protocol in Norwegian men and women

Abstract

Introduction: The aims of the present study were to provide reference values for time to exhaustion (TTE) on a modified Balke treadmill protocol, and to perform a cross-validation of TTE as a measure of maximal oxygen consumption (VO2max), in Norwegian men and women 20 – 85 years of age.

Methods: Reference values for TTE were derived from a national sample of 765 subjects. An additional sample of 119 subjects was included in the cross-validation (total n = 884), where prediction equations for VO2max was established. Results: A decline in TTE was seen with increased age. Prediction of VO2max in an independent dataset (n = 319) resulted in a R2 = 0.78 and standard error of the estimate = 4.55 ml kg-1 min-1. The observed – predicted bias was small (mean difference <1.24 ml kg-1 min-1), whereas random error was considerable (95% limits of agreement ± 7.11 – 9.70 ml kg-1 min-1) across age in both men and women.

Conclusions: Despite limitations concerning the prediction of VO2max on an individual level, TTE from the Balke protocol is a good measure of aerobic fitness in adults across a range of settings, and could be evaluated according to the suggested reference values.