The effect of chronic progressive-dose sodium bicarbonate ingestion on CrossFit-like performance: A double-blind, randomized cross-over trial

BACKGROUND: Sodium bicarbonate (SB) has been proposed as an ergogenic aid, as it improves high-intensity and resistance exercise performance. However, no studies have yet investigated SB application in CrossFit. This study examined the effects of chronic, progressive-dose SB ingestion on CrossFit-like performance and aerobic capacity. METHODS: In a randomized, double-blind, cross-over trial, 21 CrossFit-trained participants were randomly allocated to 2 groups and underwent 2 trials separated by a 14-day washout period. Participants ingested either up to 150 mg∙kg(-1) of SB in a progressive-dose regimen or placebo for 10 days. Before and after each trial, Fight Gone Bad (FGB) and incremental cycling (ICT) tests were performed. In order to examine biochemical responses, blood samples were obtained prior to and 3 min after completing each exercise test. RESULTS: No gastrointestinal (GI) side effects were reported during the entire protocol. The overall FGB performance improved under SB by ~6.1% (p<0.001) and it was ~3.1% higher compared to post placebo (PLA(post)) (p = 0.040). The number of repetitions completed in each round also improved under SB (mean from baseline: +5.8% to +6.4%). Moreover, in ICT, the time to ventilatory threshold (VT) (~8:25 min SB(post) vs. ~8:00 min PLA(post), p = 0.020), workload at VT (~218 W SB(post) vs. ~208 W PLA(post), p = 0.037) and heart rate at VT (~165 bpm SB(post) vs. ~161 bpm PLA(post), p = 0.030) showed higher SB(post) than PLA(post). Furthermore, the maximum carbon dioxide production increased under SB by ~4.8% (from ~3604 mL∙min(-1) to ~3776 mL∙min(-1), p = 0.049). Pyruvate concentration and creatine kinase activity before ICT showed higher SB(post) than PLA(post) (~0.32 mmol∙L(-1) vs. ~0.26 mmol∙L(-1), p = 0.001; ~275 U∙L(-1) vs. ~250 U∙L(-1), p = 0.010, respectively). However, the small sample size limits the wide-application of our results. CONCLUSIONS: Progressive-dose SB ingestion regimen eliminated GI side effects and improved CrossFit-like performance, as well as delayed ventilatory threshold occurrence.