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

ABSTRACT

BACKGROUND: ß-alanine (ßA) supplementation has been shown to increase intramuscular carnosine content and subsequent high-intensity performance in events lasting < 4 minutes (min), which may be dependent on total, as opposed to daily, dose. The ergogenic effect of ßA has also been demonstrated for 2000-m rowing performance prompting interest in whether ßA may be beneficial for sustained aerobic exercise. This study therefore investigated the effect of two ßA dosing strategies on 30-min rowing and subsequent sprint performance. METHODS: Following University Ethics approval, twenty-seven healthy, male rowers (age 24 ± 2 years; body-height 1.81 ± 0.02 m; body-mass 82.3 ± 2.5 kg; body-fat 14.2 ± 1.0%) were randomised in a double-blind manner to 4 weeks of i) ßA (2.4 g·d- 1, ßA1); ii) matched total ßA (4.8 g on alternate days, ßA2); or iii) cornflour placebo (2.4 g·d- 1, PL). Participants completed a laboratory 30-min rowing time-trial, followed by 3x30-seconds (s) 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-min 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-min time-trial distance significantly increased from T1-T3 within ßA1 only (7397 ± 195 m to 7580 ± 171 m, P = 0.002, ƞp2 = 0.196), including absolute average power (194.8 ± 18.3 W to 204.2 ± 15.5 W, P = 0.04, ƞp2 = 0.115) and relative average power output (2.28 ± 0.15 W·kg- 1 to 2.41 ± 0.12 W·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 min split (P ≤ 0.01), and for distance covered (P = 0.01) in the second 10-min 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 (ßA1 163.9 ± 3.8 m; ßA2 161.2 ± 3.5 m; PL 162.7 ± 3.6 m), average power (ßA1 352.7 ± 14.5 W; ßA2 342.2 ± 13.5 W; PL 348.2 ± 13.9 W) and lactate (ßA1 10.0 ± 0.9 mmol·L- 1; ßA2 9.2 ± 1.1 mmol·L- 1; PL 8.7 ± 0.9 mmol·L- 1). CONCLUSIONS: Whilst daily ßA may confer individual benefits, these results demonstrate limited impact of ßA (irrespective of dosing strategy) on 30-min rowing or subsequent sprint performance. Further investigation of ßA dosage > 2.4 g·d- 1 and/or chronic intervention periods (> 4-8 weeks) may be warranted based on within-group observations.