Caffeine Combined With Sodium Bicarbonate Improves Pacing and Overall Performance During a High-Intensity Time Trial

: No study has demonstrated the effects of sodium bicarbonate plus caffeine (NaHCO + CAF) on power output (PO) distribution (e.g., pacing), physiological parameters and energy system contribution during a 4-km cycling time trial (TT). Thus, we aimed to investigate the effects of NaHCO + CAF on pacing, physiological parameters, and energy system contribution during a 4-km cycling TT. : Using a double-blind and counterbalanced design, 10 cyclists performed three ingestion protocols (NaHCO + CAF, NaHCO and placebo) followed by a 4-km cycling TT. : 100 min after substance ingestion, the magnitude of change in blood pH and bicarbonate concentration [HCO] for NaHCO + CAF (+0.04 ± 0.03 and +5.9 ± 1.6 mmol·L, respectively, < .05) and NaHCO (+0.02 ± 0.03 and +4.1 ± 2.0 mmol·L, respectively, < .05) was more pronounced than in placebo (-0.01 ± 0.02 and 0.4 ± 0.9 mmol·L, respectively). The increase in plasma lactate concentration was more pronounced in NaHCO + CAF than in NaHCO and placebo ( < .05). Mean ventilation and carbon dioxide production were higher in NaHCO + CAF compared to NaHCO and placebo ( < .05). The PO and anaerobic power output were increased at the beginning of the 4-km TT ( < .05) in NaHCO + CAF compared to the other two conditions, resulting in an improved overall performance ( < .05). : NaHCO + CAF results in a higher PO and increased anaerobic contribution and respiratory parameters during a 4-km cycling TT.