Effect of induced alkalosis on perception of exertion during intermittent exercise.

The purpose of this study was to evaluate the effects of metabolic alkalosis on differentiated ratings of perceived exertion during intermittent high-intensity exercise. Six endurance-trained females participated as subjects in this investigation. Each subject underwent three separate experimental trials in which NaHCO3 was ingested in either a single (0.3 g NaHCO3/kg body wt) or periodic schedule (0.12 g NaHCO3/kg body wt initially, with 0.18 g/kg body wt distributed in equal doses before each 5-min exercise bout). Calcium carbonate served as a placebo control. An intermittent exercise protocol was used in which each subject rode a cycle ergometer at 90% maximum O2 consumption for 5 min. Within each acid-base condition, the exercise protocol was repeated three times with 10-min rest periods interspersed. Differentiated ratings of perceived exertion for the legs (RPE-L), chest (RPE-C), and overall body (RPE-O) were attenuated under alkalotic treatment relative to placebo control regardless of pattern of NaHCO3 administration. RPE-L, RPE-C, and RPE-O were negatively correlated to the bicarbonate concentration of venous blood. This investigation suggests that perception of effort during high-intensity intermittent exercise can be related to buffering capacity of the blood.