The effects of enteric-coated sodium bicarbonate supplementation on 2 km rowing performance in female CrossFit® athletes

Purpose: Sodium bicarbonate (SB) supplementation can improve exercise performance, but few studies consider how effective it is in female athletes. The aim of the study was to establish the effect of individually timed pre-exercise SB ingestion on 2 km rowing time trial (TT) performance in female athletes. Methods: Eleven female CrossFit® athletes (mean ± SD age, 29 y ± 4 y, body mass, 64.5 kg ± 7.1 kg, height, 1.7 m ± 0.09 m, peak oxygen uptake [VO2peak], 53.8 ± 5.7 mL·kg−1∙min−1). An initial trial identified individual time-to-peak [HCO3−] following enteric-coated 0.3 g·kg−1 BM SB ingestion. Participants then completed a 2 km TT familiarisation followed by a placebo (PLA) or SB trial, using a randomised cross-over design. Results: The ingestion of SB improved rowing performance (514.3 ± 44.6 s) compared to the PLA (529.9 ± 45.4 s) and FAM trials (522.2 ± 43.1 s) (p = 0.001, pη2 = 0.53) which represents a 2.24% improvement compared to the PLA. Individual time-to-peak alkalosis occurred 102.3 ± 22.1 min after ingestion (range 75–150 min) and resulted in increased blood [HCO3-] of 5.5 ± 1.5 mmol⋅L−1 (range = 3.8–7.9 mmol⋅L−1). The change in blood [HCO3-] was significantly correlated with the performance improvement between PLA and SB trials (r = 0.68, p = 0.020). Conclusions: Ingesting a 0.3 g·kg−1 BM dose of enteric-coated SB improves 2 km rowing performance in female athletes. The improvement is directly related to the extracellular buffering capacity even when blood [HCO3-] does not change ≥ 5.0 mmol⋅L−1.