Effect of induced alkalosis on perception of exertion during exercise recovery

In this investigation we studied the effect of manipulating the acid-base balance through sodium bicarbonate (NaHCO(3)) ingestion on ratings of perceived exertion for the overall body (RPE-O) and on differentiated ratings for the leg and chest (RPE-L, RPE-C) during exercise recovery. Six women of college age underwent 3 experimental conditions in which NaHCO(3) was ingested in either a single (bolus) or periodic (distributed throughout the exercise) dosage, with calcium carbonate serving as a placebo control. Each subject pedaled a cycle ergometer at 90% Vo(2)peak for three 5-minute exercise sessions, each separated by 10 minutes of recovery. Repeated-measures analysis of variance with Tukey post hoc analysis was performed for acid-base and perceptual variables. Results indicate that a gradient of acid-base balance was established such that pH and bicarbonate concentration were significantly greater (p < 0.05) for the single condition in comparison with periodic and placebo conditions, and the periodic condition was significantly greater (p < 0.05) than placebo. The average percentage of recovery for RPE-L and RPE-C was 8% greater (p < 0.05) for the single condition than for the periodic and placebo conditions, at the first and second minutes of recovery. During the first minute of recovery, the average percentage of recovery for RPE-O was 10% greater (p < 0.05) for the single condition than for the placebo condition. During the second minute of recovery, the percentage of recovery for RPE-O for the single condition was significantly greater than those for both the periodic and placebo conditions by an average of 9%. These results strengthen the relationship between the acid-base balance and the subjective perception of exertion. In addition, this study provides preliminary data in support of RPE as an adjunct measure to quantify the extent of recovery from exercise.