Author(s): MEI, T., CAI, Z.P., Institution: BEIJING SPORT UNIVERSITY, Country: CHINA, Abstract-ID: 502

INTRODUCTION:
β-alanine is a widely used ergogenic aid with potential benefits for high-intensity exercise. While chronic β-alanine supplementation has been extensively investigated, evidence regarding the acute effects of β-alanine ingestion on repeated-sprint performance and hydration-related markers remains limited. This study examined the effects of acute β-alanine ingestion on repeated-sprint performance and hydration-related markers in physically active young men.
METHODS:
A double-blind, placebo-controlled, randomized crossover design was employed. Twenty-one physically active men (24 ± 1.21 years; 178 ± 4.71 cm; 75 ± 6.18 kg) completed one familiarization session and three experimental trials separated by one-week washout periods. In each trial, participants ingested capsules of β-alanine (20 mg/kg, β20; 40 mg/kg, β40) or placebo (PLA). A standardized warm-up began 20 min post-ingestion, and the repeated-sprint test began 30 min post-ingestion. The sprint protocol consisted of 2 sets of 6 x 35 m all-out sprints, with 20 s recovery between sprints and 4 min recovery between sets. Sprint time and sprint end speed were recorded. Sweat and urine samples were collected to assess sweat osmolality, urine osmolality, and urine pH.
RESULTS:
Total sprint time during the repeated-sprint test differed significantly among conditions (PLA: 62.43 ± 2.27 s; β20: 60.97 ± 2.17 s; β40: 59.74 ± 1.96 s; p < 0.001). The fatigue index was lower in β40 than PLA (PLA: 0.14 ± 0.02; β20: 0.13 ± 0.02; β40: 0.13 ± 0.01; p = 0.01). Sprint end speed was higher in β40 than PLA, with differences in maximal (8.40 ± 0.43, 8.46 ± 0.47, and 8.50 ± 0.48 m/s for PLA, β20, and β40; p = 0.03), minimal (7.27 ± 0.38, 7.29 ± 0.41, and 7.35 ± 0.43 m/s; p = 0.04), and mean values (7.88 ± 0.47, 7.77 ± 0.51, and 7.91 ± 0.44 m/s; p = 0.04). Post-ingestion urine osmolality was higher in β40 than PLA and β20 (724.67 ± 42.39, 736.43 ± 38.51, and 753.95 ± 38.12 mOsm/kg; p = 0.04). Post-exercise urine pH was higher in both β20 and β40 than PLA (PLA: 5.87 ± 0.21; β20: 6.14 ± 0.31; β40: 6.19 ± 0.34; p = 0.01). Sweat osmolality differed among conditions (PLA: 286.86 ± 4.86; β20: 289.95 ± 5.86; β40: 290.48 ± 4.80 mOsm/kg; p = 0.01).
CONCLUSION:
These findings indicate that acute pre-exercise β-alanine ingestion may improve repeated-sprint performance, with more consistent benefits at 40 mg/kg than 20 mg/kg. However, the higher dose was accompanied by increased sweat and urine osmolality and higher urine pH, indicating altered hydration-related markers. Hydration management should be planned when applying acute high-dose β-alanine before high-intensity sprint exercise.