The effect of induced alkalosis and acidosis on plasma lactate and work output in elite oarsmen

Summary In order to test the effect of artificially induced alkalosis and acidosis on the appearance of plasma lactate and work production, six well-trained oarsmen (age=23.8±2.5 years; mass=82.0±7.5 kg) were tested on three separate occasions after ingestion of 0.3 g·kg⁻¹. NH₄Cl (acidotic), NaHCO₃ (alkalotic) or a placebo (control). Blood was taken from a forearm vein immediately prior to exercise for determination of pH and bicarbonate. One hour following the ingestion period, subjects rowed on a stationary ergometer at a pre-determined sub-maximal rate for 4 min, then underwent an immediate transition to a maximal effort for 2 min. Blood samples from an indwelling catheter placed in the cephalic vein were taken at rest and every 30 s during the 6 min exercise period as well as at 1, 3, 6, 9, 12, 15, 18, 21, 25 and 30 min during the passive recovery period. Pre-exercise blood values demonstrated significant differences (p<0.01) in pH and bicarbonate in all three conditions. Work outputs were unchanged in the submaximal test and in the maximal test (p>0.05), although a trend toward decreased production was evident in the acidotic condition. Analysis of exercise blood samples using ANOVA with repeated measures revealed that the linear increase in plasma lactate concentration during control was significantly greater than acidosis (p<0.01). Although plasma lactate values during alkalosis were consistantly elevated above control there was no significant difference in the linear trend (p>0.05). During recovery, there was no significant difference in the rate of lactate disappearance amongst the three conditions. It is concluded that under this protocol artificial manipulation of the acid-base status of the blood does not significantly influence work production despite significantly reduced plasma lactate concentrations during acidosis. The inability of these pH changes to alter exercise performance emphasizes the relative importance of the intracellular and the extracellular buffer systems in well trained athletes.