The effect of two β-alanine dosing strategies on 30-minute rowing performance: a randomized, controlled trial

Background: β-alanine (βA) supplementation has been shown to increase intramuscular carnosine content and subsequent high-intensity performance in events lasting <4 minutes, which may be dependent on total, as opposed to daily, dose. The ergogenic effect of βA has also been demonstrated for 2000-m rowing performance prompting interest in whether βA may be beneficial for sustained aerobic exercise. This study therefore investigated the effect of two βA dosing strategies on 30-minute rowing and subsequent sprint performance. Methods: Following University Ethics approval, twenty-seven healthy, male rowers (age: 24±2 years; body-height: 1.81±0.02m; body-mass: 82.3±2.5kg; body-fat: 14.2±1.0%) were randomised in a double-blind manner to 4 weeks of: i) βA (2.4 g·d-1, βA1); ii) matched total βA (4.8g on alternate days, βA2); or iii) cornflour placebo (2.4 g·d-1, PL). Participants completed a laboratory 30-minute rowing time-trial, followed by 3x30s maximal sprint efforts at days 0, 14 and 28 (T1-T3). Total distance (m), average power (W), relative average power (W·kg-1), cardio-respiratory measures and perceived exertion were assessed for each 10-minute split. Blood lactate ([La-]b mmol·L-1) was monitored pre-post time-trial and following maximal sprint efforts. A 3-way repeated measures ANOVA was employed for main analyses, with Bonferonni post-hoc assessment (P≤0.05). Results: Total 30-minute time-trial distance significantly increased from T1-T3 within βA1 only (7397±195m to 7580±171m, P=0.002, ƞp2 = 0.196), including absolute average power (194.8±18.3W to 204.2±15.5W, P=0.04, ƞp2=0.115) and relative average power output (2.28±0.15W·kg-1 to 2.41±0.12W·kg-1, P=0.031, ƞp2= 0.122). These findings were potentially explained by within-group significance for the same variables for the first 10 minute split (P≤0.01), and for distance covered (P=0.01) in the second 10-minute split. However, no condition x time interactions were observed. No significant effects were found for sprint variables (P>0.05) with comparable values at T3 for mean distance (βA1: 163.9±3.8m; βA2: 161.2±3.5m; PL: 162.7±3.6m), average power (βA1: 352.7±14.5W; βA2: 342.2±13.5W; PL: 348.2±13.9W) and lactate (βA1: 10.0±0.9mmol·L-1; βA2: 9.2±1.1mmol·L-1; PL: 8.7±0.9mmol·L-1). Conclusions: Whilst daily βA may confer individual benefits, these results demonstrate limited impact of βA (irrespective of dosing strategy) on 30-minute rowing or subsequent sprint performance. Further investigation of βA dosage > 2.4 g·d-1 and/or chronic intervention periods (>4-8 weeks) may be warranted based on within-group observations.