Description and predictive value of a novel method for determining the respiratory compensation point using standard scores.

The ability to use data from tests of maximum aerobic capacity to estimate the ventilatory threshold and point of respiratory compensation (RCP) is useful for coaches and practitioners in the development of training schemes. Current methods for determining the RCP generally involve identifying deflections in respiratory variables when examined alongside minute ventilation. This investigation describes a novel mathematical method for determining RCP using standard scores (Z-scores) for minute ventilation (VE) and oxygen consumption (VO2). This method allows for the point where ventilation becomes disproportionate to oxygen consumption to be quantified as an intersection between 2 lines of best fit. This novel Z-score method was compared with a well-described determination of RCP and was found to be highly correlated (r = 0.926, p ≤ 0.001). The Z-score method was also found to be related to 10-km road race performance using regression analysis (R(2) = 0.824, p ≤ 0.001) in a group of 18 athletes and recreational runners. Based on the evidence from this study, the Z-score method of RCP determination is highly correlated to previous methods and endurance performance. This method potentially offers further benefits as it is not reliant on visual determination of changes in slope in variables of interest but rather on the mathematical solution to the intersection of 2 regression lines.