Effects of Oral Lactate Supplementation on Acid–Base Balance and Prolonged High-Intensity Interval Cycling Performance

Lactate is an important energy intermediate and metabolic buffer, and may be ergogenic. We investigated if lactate supplementation is an effective approach to enhance the exercise performance and acid-base balance of trained cyclists during exercise devised to simulate the demands of endurance road race cycling. Sixteen endurance-trained male cyclists (V·O_2max 59 ± 7 mL·kg^-1·min^-1) consumed 120 mg·kg^-1 body mass of lactate or a placebo 70 min prior to performing an exercise performance test, comprising five repeated blocks consisting of 1 km and 4 km time trials interspersed with 10 min of moderate-intensity exercise. Blood acid-base balance (including [H⁺] and [HCO₃^-]), heart rate, perceived exertion, and gastro-intestinal tolerance were assessed. There was no effect of lactate supplementation on exercise performance (<i>p</i> = 0.320), despite a reduction in RPE (<i>p</i> = 0.012) and increases in [SID] (<i>p</i> = 0.026) and [HCO₃^-] (<i>p</i> = 0.041). In addition, gastro-intestinal side effects were observed, but there was no effect on heart rate. Lactate supplementation did not improve exercise performance, despite positive changes in acid-base balance and RPE. This suggests that the alkalising effects of the supplement can reduce perceived effort, but these benefits do not translate into performance improvements.