The effect of induced alkalosis and acidosis on endurance running at an intensity corresponding to 4 mM blood lactate

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Abstract
Short-term exercise is favourably affected by induced alkalosis and adversely affected by induced acidosis, although no study has examined these effects on prolonged high intensity exercise. This study examined the effects of induced alkalosis and acidosis on treadmill running at a velocity corresponding to a blood lactate concentration of 4mM (V-4mM). The V-4mM was determined in seven healthy males using a continuous incremental test. Each subject then ran to exhaustion at an individually determined V-4mM on three separate occasions, following the ingestion of 0·2gkg body weight−1 of either sodium bicarbonate (B), ammonium chloride (A) or sodium chloride (placebo, PL). Finger-prick blood samples were taken prior to ingestion, pre-exercise and post-exercise. The blood was analysed for pH, bicarbonate and lactate concentrations. Treatment B produced a significant increase in blood pH and blood bicarbonate level (p<0·01) from pre-ingestion to pre-exercise, whereas A caused a significant decrease in blood pH and blood bicarbonate (p 0·05). Pre-exercise blood pH and bicarbonate concentrations were significantly higher for B (p<0·01) and lower for A (p<0·01) than for PL. Treatment B increased time to exhaustion by 17% (263 s) compared to PL, the direction of the change being positive in all subjects (p0·05). Results suggest that induced alkalosis has beneficial effects on prolonged, intense exercise whereas ammonium chloride adversely affects such performance, either by the induced acidosis or by the metabolic effects.