Exercise protocol
All participants completed the exercise protocol during their normal training time and at the same time of day (± 1 h) (range: 5–8 pm). Following a familiarisation trial that entailed completing the interval sets, the experimental protocol was repeated on two occasions 1 week apart. Each participant was asked to swim 50 m (front crawl), from a competitive diving block, at their maximum effort and repeat this 8 times. After each 50 m sprint, participants undertook a 50 m active recovery swim requiring them to swim at their normal warm–up pace. Each exercise bout was run off a 5 min base, which left the participants with approximately 3 min passive recovery. Although similar exercise protocols have utilised passive recovery (Gao et al. On both testing sessions participants ingested either a solution of NaHCOFingertip capillary blood samples were taken at three time points; baseline (pre-ingestion), 60 min post-NaHCO