Effect of Warm-Up and Sodium Bicarbonate Ingestion on 4-km Cycling Time-Trial Performance.

Abstract

To examine whether an ecologically valid, intermittent, sprint-based warm-up strategy impacted the ergogenic capacity of individualized sodium bicarbonate (NaHCO3) ingestion on 4-km cycling time-trial (TT) performance. A total of 8 male cyclists attended 6 laboratory visits for familiarization, determination of time to peak blood bicarbonate, and 4 × 4-km cycling TTs. Experimental beverages were administered doubleblind. Treatments were conducted in a block-randomized, crossover order: intermittent warm-up + NaHCO3 (IWSB), intermittent warm-up + placebo, control warm-up + NaHCO3 (CWSB), and control warm-up + placebo (CWP). The intermittent warm-up comprised exercise corresponding to lactate threshold (5min at 50%, 2min at 60%, 2min at 80%, 1min at 100%, and 2min at 50%) and 3 × 10-second maximal sprints. The control warm-up comprised 16.5minutes cycling at 150W. Participants ingested 0.3g·kg body mass-1 NaHCO3 or 0.03g·kg body mass-1 sodium chloride (placebo) in 5mL·kg body mass-1 fluid (3:2, water and sugar-free orange squash). Paired t tests were conducted for TT performance. Hematological data (blood bicarbonate and blood lactate) and gastrointestinal discomfort were analyzed using repeated-measures analysis of variance. Performance was faster for CWSB versus IWSB (5.0 [6.1]s; P = .052) and CWP (5.8 [6.0]s; P = .03). Pre-TT bicarbonate concentration was elevated for CWSB versus IWSB (+9.3mmol·L-1; P < .001) and CWP (+7.1mmol·L-1; P < .001). Post-TT blood lactate concentration was elevated for CWSB versus CWP (+2.52mmol·L-1; P = .022). Belching was exacerbated pre-warm-up for IWSB versus intermittent warm-up +placebo (P = .046) and CWP (P = .027). An intermittent, sprint-based warm-up mitigated the ergogenic benefits of NaHCO3 ingestion on 4-km cycling TT performance.