Sodium Bicarbonate Supplementation Enhances Repeated High‐Intensity Interval Training Performance and Time Above 90% of V˙O2max in Well‐Trained Cyclists

Abstract

ABSTRACT This study investigated the effects of sodium bicarbonate (SB) supplementation on physiological responses and performance during submaximal exercise, high‐intensity interval training (HIT) and repeated Wingate sprints in well‐trained cyclists. Twenty‐four participants (♂ = 15, maximal oxygen uptake [V˙O2max] = 72 ± 5 mL·min−1 kg−1; ♀ = 9, V˙O2max = 57 ± 6 mL·min−1 kg−1) performed one screening and familiarisation session and two experimental sessions in a randomised, double‐blind and crossover design. Participants ingested SB (∼0.26 g·kg−1) or an appearance‐matched placebo (PLA) 2 hours before the experimental session. Each session consisted of a step‐test protocol followed by five 5 min HIT bouts (3 × 40 s maximal efforts with 60 s recovery at power output (PO) equal to 3 mmol·L−1 [blood lactate]) and four 30 sec Wingate sprints. Cycling economy and fractional utilisation of V˙O2max were evaluated during a submaximal step test. During HIT bouts, PO was significantly higher in SB (2.0 ± 5.4%, mean difference (MD): 8.1 ± 22.1 W, p = 0.045, ηp2 = 0.171), accompanied by increased oxygen uptake (MD: 60.1 ± 124.7 mL·min−1, p = 0.006, ηp2 = 0.281) and greater time spent above 90% V˙O2max (MD: 23.7 ± 52.6 s, p = 0.012, ηp2 = 0.246). In the Wingate sprints, cyclists demonstrated significantly greater PO following SB ingestion (2.0 ± 4.7%, MD: 11.6 ± 26.8 W, p = 0.002, ηp2 = 0.342). This was accompanied by higher blood levels of bicarbonate, pH and lactate (p < 0.001, ηp2 = 0.557; p < 0.001, ηp2 = 0.548; p < 0.001, ηp2 = 0.558, respectively). Cycling economy and fractional utilisation of V˙O2max were unaffected by SB supplementation (p = 0.977 and p = 0.818). SB supplementation increased PO and time above 90% V˙O2max during HIT and PO during repeated Wingate sprints. Whether this translates into superior long‐term adaptations, such as enhanced V˙O2max and sprint performance, remains to be investigated.