The effects of creatine loading on oxygen uptake kinetics during heavy exercise

Abstract

The kinetics of oxygen uptake during the rest to exercise transition are thought to be modulated by intracellular metabolic processes. Evidence suggests that increased phosphocreatine stores may impact the kinetics of VO2, namely, slowing kinetics due to the now increased ATP buffering capacity. Thus, the purpose of this study was to test the hypothesis that creatine loading would induce slowed VO2 kinetics during heavy leg cycling. Four (N=4) subjects completed three separate exercise bouts of heavy (supra‐lactate threshold) exercise both prior to and following a creatine loading regimen. VO2 was measured continuously at the mouth during exercise and recovery for each bout. During the on‐transition, the total amplitude was reduced following creatine loading (Atot: Control 1.22±0.26 vs Creatine 0.97±0.20 L/min, p = 0.03). The time constant during the off‐transition was also slower during the creatine trials (Tau: Control 36.4±9.3 vs Creatine 53.3±7.6 sec, p = 0.02). These findings suggest that an increase in the temporal buffering capacity of phosphocreatine reduces the on‐transient VO2 as well as, slowing the recovery kinetics of VO2.