Metabolic and Exercise Performance Responses to Two Different Oral Doses of Calcium Lactate

Abstract

Evidence suggests that acidosis promotes fatigue during high-intensity exercise. Oral supplementation with 120 mg lactate · kg bm-1 has been shown to increase blood bicarbonate (HCO3-) levels and enhance exercise performance in trained cyclists. However, similar supplementation has been ineffective in improving exercise performance in untrained subjects. PURPOSE: We wished to confirm or refute earlier data supporting the positive effect of lactate supplementation on exercise performance in trained subjects. Secondly, we sought to investigate dose-response relationships by testing the effects of two different lactate dose levels on HCO3- and exercise performance in trained subjects. METHODS: 12 trained cyclists (11 M, 1 F, 21 ± 2 yr, 70.1 ± 7.3 kg) performed a graded exercise test to exhaustion to determine VO2max and power output at VO2max (MPO). Subjects returned on three occasions to perform an interval performance test (IPT) following the consumption of three treatments: 120 mg lactate · kg bm-1 (L120), 300 mg lactate · kg bm-1 (L300), or placebo (PL). HCO3- levels were assessed immediately prior to consumption of the treatments (PreCon) and 70 min post consumption (PostCon). Immediately following PostCon, subjects performed the IPT consisting of 4, 1-min intervals at 100% of MPO, followed by a fifth effort at 100% MPO to exhaustion. Intervals were separated by 1-min of recovery at 25% of MPO. All testing was performed on an electronically braked cycle ergometer. One and two-way ANOVAs were used to analyze HCO3- and time to exhaustion (TTE) on the fifth effort of the IPT. RESULTS: Compared to PreCon, PostCon HCO3- increased in L120 by 10%, (P = 0.03) and L300 by 9% (P = 0.02) with no significant difference observed between lactate treatments (P = 0.74). No significant change in HCO3- was seen following consumption of PL (< - 0.1%, P = 0.98). TTE in PL was 134 ± 30 s and increased significantly in L120 (153 ± 25 s, P = 0.004) and in L300 (169 ± 37 s, P = 0.001) with no significant difference between L120 and L300 (P = 0.09). CONCLUSIONS: Consumption of 120 or 300 mg lactate · kg bm-1 increases blood HCO3- and improves exercise performance during high-intensity exercise bouts of approximately 120 - 180 s. However, consuming 300 mg lactate · kg bm-1 provides no clear ergogenic effect when compared to consuming 120 mg lactate · kg bm-1.