Noninvasive estimation of the lactate threshold in a subject with dissociated ventilatory and pulmonary gas exchange indices : a case report

This case report describes the responses to incremental work-rate exercise in a healthy subject (with normal pulmonary function), for whom the pulmonary gas exchange (V-slope) and ventilatory-related indexes (ie, ventilatory equivalents and end-tidal partial pressures for O2 and CO 2) uncharacteristically do not occur at the same metabolic rate. Based on the results of additional constant-work-rate exercise tests, we propose that in the (occasional) event of such a dissociation between the V-slope and ventilatory-related responses normally associated with the lactate threshold (θL), then the V-slope index should take priority as the θL estimator.