Assessment of double anaerobic threshold in trained subjects

Background: Regular training increases Anaerobic Threshold (AT) and improves ventilatory efficiency during exercise. A presence of a Double AT (DT), a delayed ventilatory response to CO2 increase during exercise, was described in some healthy subjects, and may represent a favorable adaptation mechanism for trained subjects. The aim was to investigate the prevalence of DT in trained individuals and the relationship between training and ventilatory efficiency.MethodsMaximal CardioPulmonary Exercise Test (CPET) of trained subjects were analysed for assessment of AT with the metabolic (V-slope analysis, MetAT) and the ventilatory methods (end-tidal and ventilatory equivalent methods, VentAT). Trained subjects were assigned to groups DT+ or DT- based on the presence/absence of DT, respectively. Trained subjects were also classified by type of sport practiced. Determinants of ventilatory efficiency were assessed at adjusted multivariate regression analysis.ResultsDT was identified in 52 cases out of 205 enrolled (25.4%). No differences by age, sex, body mass index and peak CPET parameters were observed between groups. DT+ subjects had a longer duration and greater ΔVO2 values of isocapnic buffering period. Ventilatory efficiency was negatively associated (better values) with the presence of a DT (p = 0.017). Type of sport practiced did not influence the prevalence of DT nor the ventilatory efficiency response.ConclusionDT was found in 25.4% of trained people. The presence of DT is not influenced by the type of training and is not related to maximal aerobic capacity; however, subjects with a DT have a greater isocapnic buffering period and a better ventilatory efficiency.