Effects of β-alanine supplementation and high-intensity interval training on endurance performance and body composition in men; a double-blind trial

Background: Intermittent bouts of high-intensity exercise result in diminished stores of energy substrates, followed by an accumulation of metabolites, promoting chronic physiological adaptations. In addition, β-alanine has been accepted has an effective physiological hydrogen ion (H+) buffer. Concurrent high-intensity interval training (HIIT) and β-alanine supplementation may result in greater adaptations than HIIT alone. The purpose of the current study was to evaluate the effects of combining β-alanine supplementation with high-intensity interval training (HIIT) on endurance performance and aerobic metabolism in recreationally active college-aged men. Methods: Forty-six men (Age: 22.2 ± 2.7 yrs; Ht: 178.1 ± 7.4 cm; Wt: 78.7 ± 11.9; VO₂peak: 3.3 ± 0.59 l·min-1) were assessed for peak O₂ utilization (VO₂peak), time to fatigue (VO2TTE), ventilatory threshold (VT), and total work done at 110% of pre-training VO₂peak (TWD). In a double-blind fashion, all subjects were randomly assigned into one either a placebo (PL - 16.5 g dextrose powder per packet; n = 18) or β-alanine (BA - 1.5 g β-alanine plus 15 g dextrose powder per packet; n = 18) group. All subjects supplemented four times per day (total of 6 g/day) for the first 21-days, followed by two times per day (3 g/day) for the subsequent 21 days, and engaged in a total of six weeks of HIIT training consisting of 5-6 bouts of a 2:1 minute cycling work to rest ratio. Results: Significant improvements in VO₂peak, VO₂ TTE, and TWD after three weeks of training were displayed (p < 0.05). Increases in VO₂peak, VO₂TTE, TWD and lean body mass were only significant for the BA group after the second three weeks of training. Conclusion: The use of HIIT to induce significant aerobic improvements is effective and efficient. Chronic BA supplementation may further enhance HIIT, improving endurance performance and lean body mass.