Efficacy of sodium bicarbonate ingestion strategies for protecting blinding

Sodium bicarbonate (NaHCO₃) is a widely researched ergogenic aid, but the optimal blinding strategy during randomised placebo-controlled trials is unknown. In this multi-study project, we aimed to determine the most efficacious ingestion strategy for blinding NaHCO₃ research. During study one, 16 physically active adults tasted 0.3 g kg^-1 body mass NaHCO₃ or 0.03 g kg^-1 body mass sodium chloride placebo treatments given in different flavour (orange, blackcurrant) and temperature (chilled, room temperature) solutions. They were required to guess which treatment they had received. During study two, 12 recreational athletes performed time-to-exhaustion (TTE) cycling trials (familiarisation, four experimental). Using a randomised, double-blind design, participants consumed 0.3 g kg^-1 body mass NaHCO₃ or a placebo in 5 mL kg^-1 body mass chilled orange squash/water solutions or capsules and indicated what they believed they had received immediately after consumption, pre-TTE and post-TTE. In study one, NaHCO₃ prepared in chilled orange squash resulted in the most unsure ratings (44%). In study two, giving NaHCO₃ in capsules resulted in more unsure ratings than in solution after consumption (92 vs 33%), pre-TTE (67 vs. 17%) and post-TTE (50 vs. 17%). Administering NaHCO₃ in capsules was the most efficacious blinding strategy which provides important implications for researchers conducting randomised placebo-controlled trials.