Purpose: The purpose of this study was to investigate the effects of 28 d of ß-alanine supplementation on 4-min cycling time trial performance and to determine whether there was an additive effect of combined ß-alanine and sodium bicarbonate (NaHCO3) supplementation on high-intensity cycling performance. Methods: Fourteen highly trained cyclists (mean ± SD: age = 25.4 ± 7.2 yr, mass = 71.1 ± 7.1 kg, VO2max = 66.6 ± 5.7 mL/kg·min) supplemented for 28 d with ß-alanine (65 mg/kg body mass each day) or placebo. A maximal 4-min bout of cycling was performed before supplementation (baseline) and twice after supplementation: after ingestion of NaHCO3 (300 mg/kg body mass) and ingestion of a placebo using a randomized crossover design with 2 d between trials. Blood pH and HCO3- concentration were determined before loading (postsupplementation trials) and at pretest and posttest. Results: In the acute NaHCO3 loading trials, blood pH and HCO3- were elevated from before loading to pretest, and the magnitude of the change in HCO3- from pretest to posttest was significantly greater compared with the acute placebo loading trial (P < 0.001). Average power output in the 4-min cycling performance trial was increased in placebo + NaHCO3 (+3.1% ± 1.8%) and ß-alanine + NaHCO3 (+3.3% ± 3.0%) compared with baseline (P < 0.05). ß-alanine + placebo did not significantly improve average power output compared with baseline (+1.6% ± 1.7%, P = 0.20); however, magnitude-based inferences demonstrated that ß-alanine + placebo was associated with a 37% likelihood of producing average power improvements. Conclusions: In trained cyclists, ß-alanine supplementation did not significantly improve 4-min cycling performance; however, there may be a small meaningful improvement in performance. Acute NaHCO3 supplementation significantly improved 4-min cycling performance. There seemed to be a minimal additive effect of combined ß-alanine and NaHCO3 supplementation.
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