Resumen de Prediction of Aerobic and Anaerobic Capacities of Elite Cyclists From Changes in Lactate During Isocapnic Buffering Phase

Mohsen Hasanli, Roohollah Nikooie, Malihe Aveseh, Fashi Mohammad

• This study predicted aerobic and anaerobic capacities using relative changes of arterial blood lactate during the isocapnic buffering phase (relative [La]ISBP). Fourteen male professional cyclists (sprint-trained [n = 6] and endurance [n = 8]) performed 2 exercise sessions to exhaustion on a cycle ergometer; 1 incremental standard test to determine the isocapnic buffering phase, buffering capacities, and relative [La]ISBP and 1 supramaximal exercise test to determine maximal accumulated oxygen deficit (MAOD). The time between Lactate threshold (LT) and respiratory compensatory threshold (RCT) was considered to be the isocapnic buffering phase. Total buffering capacity was calculated as [DELTA][La]·[DELTA]pH-1. Bicarbonate buffering was calculated as [DELTA][HCO3-]·[DELTA]pH-1, and the difference between -[DELTA][La]·[DELTA]pH-1 and [DELTA][HCO3-]·[DELTA]pH-1 was considered as nonbicarbonate buffering. The lactate concentration for LT (p <= 0.05) and RCT (p <= 0.05), and relative [La]ISBP (p < 0.01) were significantly lower for endurance cyclists than for sprint-trained cyclists. A significant difference was found for bicarbonate buffering capacity between groups (p < 0.01). A significant correlation was found between relative [La]ISBP with (r = -0.71, p <= 0.05) and MAOD (r = 0.73, p < 0.01). Relative [La]ISBP was useful for predicting aerobic power (R2 = 51%) and anaerobic capacity (R2 = 53%). These results demonstrated that relative [La]ISBP is an important variable in intermediary metabolism and in addition to and LT is recommended for better evaluation of performance of athletes who show nearly equal contributions from the aerobic and anaerobic energy systems during exercise.