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

Abstract

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 Δ[La]·ΔpH. Bicarbonate buffering was calculated as Δ[HCO3]·ΔpH, and the difference between -Δ[La]·ΔpH and Δ[HCO3]·ΔpH 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 (Equation is included in full-text article.)(r = -0.71, p ≤ 0.05) and MAOD (r = 0.73, p < 0.01). Relative [La]ISBP was useful for predicting aerobic power (R = 51%) and anaerobic capacity (R = 53%). These results demonstrated that relative [La]ISBP is an important variable in intermediary metabolism and in addition to (Equation is included in full-text article.)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.

The Relationship between the Isocapnic Buffering Phase and Ventilatory Threshold in Endurance Athletes and Team Sport Athletes during an Incremental Exercise Test

“…During the ICB phase, more H + has been reported to be buffered by the non-bicarbonate buffer system in sprint-trained cyclists than in endurance cyclists (8). Depending on differences in the metabolic pathways used during training sessions, the AT, the RCP and consequently the ICB phase varies between aerobic-and anaerobic-trained athletes.…”

“…On the other hand, according to some researchers, the ICB is not related to endurance performance (11). Recently, it has been shown that the relative ICB phase can be useful for predicting both the aerobic and anaerobic capacities in athletes (8).…”

“…A few studies have compared the ICB phase of athletes with aerobic training to those with anaerobic training. These studies found greater lactate increases during the ICB phase in anaerobic-trained athletes versus in endurancetrained athletes (8,12,13). However, to our knowledge, no investigation has attempted to compare the VO2 during the ICB phase between anaerobic-trained athletes and endurance-trained athletes.…”

“…The length of the ICB phase may be related to buffering capacity and lactate kinetics as well as the sensitivity of the carotid bodies to exercise-induced metabolic acidosis (5,(8)(9)(10). Some researchers suggested that the ICB phase contributes to the aerobic capacity in athletes (7).…”

“…The length of the ICB phase in athletes from different sports may vary depending on their training regime (8,12,13). A few studies have compared the ICB phase of athletes with aerobic training to those with anaerobic training.…”