Neither an Individualised Nor a Standardised Sodium Bicarbonate Strategy Improved Performance in High-Intensity Repeated Swimming, or a Subsequent 200 m Swimming Time Trial in Highly Trained Female Swimmers

Inconsistent swimming performances are often observed following sodium bicarbonate (NaHCO₃) ingestion, possibly because the time taken to reach peak blood buffering capacity is highly variable between individuals. Personalising NaHCO₃ ingestion based on time-to-peak blood bicarbonate (HCO₃^-) could be a solution; however, this strategy is yet to be explored in swimming, or adequately compared to standardised NaHCO₃ approaches. Therefore, six highly trained female swimmers ingested 0.3 g·kg BM^-1 NaHCO₃ in capsules to pre-determine their individual time-to-peak blood HCO₃^-. They then participated in three experimental trials, consisting of a 6 × 75 m repeated sprint swimming test, followed by a 200 m maximal time trial effort after 30 min active recovery. These experiments were conducted consuming a supplement at three different timings: individualised NaHCO₃ (IND: 105-195 min pre-exercise); standardised NaHCO₃ (STND: 150 min pre-exercise); and placebo (PLA: 90 min pre-exercise). Both NaHCO₃ strategies produced similar increases in blood HCO₃^- prior to exercise (IND: +6.8 vs. STND: +6.1 mmol·L^-1, <i>p</i> < 0.05 vs. PLA) and fully recovered blood HCO₃^- during active recovery (IND: +6.0 vs. STND: +6.3 mmol·L^-1 vs. PLA, <i>p</i> < 0.05). However, there were no improvements in the mean 75 m swimming time (IND: 48.2 ± 4.8 vs. STND: 48.9 ± 5.8 vs. PLA: 49.1 ± 5.1 s, <i>p</i> = 0.302) nor 200 m maximal swimming (IND: 133.6 ± 5.0 vs. STND: 133.6 ± 4.7 vs. PLA: 133.3 ± 4.4 s, <i>p</i> = 0.746). Regardless of the ingestion strategy, NaHCO₃ does not appear to improve exercise performance in highly trained female swimmers.