Linear Modeling of the V̇O 2 /PO Relationship during Constant Work Rate Exercise.

Abstract

The linear and continuous increase in power output (PO) during ramp incremental (RI) exercise causes a distinct V̇O 2 /PO relationship compared with constant work rate (CWR) exercise. Current methods enabling a translation of ramp-derived PO to CWR PO assume a linear development of the CWR V̇O 2 /PO relationship in the heavy-intensity domain. This study aimed to model the RI versus CWR V̇O 2 /PO relationship to investigate whether the loss of mechanical efficiency above GET develops linearly. A second aim was to assess the reliability of ramp-derived parameters incorporated in translation strategies. Fourteen healthy young participants (7 males; 7 females) performed an RI test and several CWR tests across the heavy- and severe-intensity domains in order to model the RI and CWR V̇O 2 /PO relationships. The CWR relationship was fitted using linear, polynomial, and exponential models. Root mean square error (RMSE) and Akaike information criterion (AIC C ) were determined to evaluate the model's goodness of fit. For reliability purposes, target PO of CWR tests were achieved using a preceding RI portion, similar to the initial RI test. The linear fit of the CWR V̇O 2 /PO relationship was associated with the lowest RMSE and AIC C . The associated R2 for the heavy-intensity domain was 0.94. Reliability measures were excellent for baseline V̇O 2 and acceptable to good for s1-ramp and s2-ramp . For MRT, a high variability was observed. This study confirmed that the CWR V̇O 2 /PO relationship in the heavy-intensity domain is linear. Therefore, these results validate the use of correction strategies that are based on a linear V̇O 2 /PO relationship for translating ramp-derived PO into their CWR equivalents.