ABSTRACT

The purpose of this study was to explore the effect of individualised sodium bicarbonate (NaHCO₃) supplementation according to a pre-established individual time-to-peak (TTP) blood bicarbonate (HCO₃⁻) on 4-km cycling time trial (TT) performance in the heat. Eleven recreationally trained male cyclists (age: 28 ± 6 years, height: 180 ± 6 cm, body mass: 80.5 ± 8.4 kg) volunteered for this study in a randomised, crossover, triple-blind, placebo-controlled design. An initial visit was conducted to determine TTP HCO₃⁻ following 0.2 g.kg⁻¹ body mass (BM) NaHCO₃ ingestion. Subsequently, on three separate occasions, participants completed a 4-km cycling TT in the heat (30 degrees centigrade; °C) (relative humidity ∼40%) following ingestion of either NaHCO₃ (0.2 g.kg⁻¹ body mass), a sodium chloride placebo (0.2 g.kg⁻¹ BM; PLA) at the predetermined individual TTP HCO₃⁻, or no supplementation (control; CON) . Absolute peak [HCO₃⁻] prior to the 4-km cycling TT's was elevated for NaHCO₃ compared to PLA (+2.8 mmol.l⁻¹; p = 0.002; g = 2.2) and CON (+2.5 mmol.l⁻¹; p < 0.001; g = 2.1). Completion time following NaHCO₃ was 5.6 ± 3.2 s faster than PLA (1.6%; CI: 2.8, 8.3; p = 0.001; g = 0.2) and 4.7 ± 2.8 s faster than CON (1.3%; CI: 2.3, 7.1; p = 0.001; g = 0.2). These results demonstrate that NaHCO₃ ingestion at a pre-established individual TTP HCO₃⁻ improves 4-km cycling TT performance in the heat, likely through enhancing buffering capacity.

Highlights

• This is the first time NaHCO₃ ingestion has been shown to improve 4-km cycling TT performance in conditions of high ambient heat.

• A smaller dose of NaHCO₃ (0.2 g.kg⁻¹ BM) is ergogenic in the heat, which is smaller than the dose typically ingested for sports performance (0.3 g.kg⁻¹ BM). This is important, as gastrointestinal discomfort is typically lower as the dose reduces.

• This study suggests that the individualised time-to-peak HCO₃⁻ ingestion strategy with lower doses of NaHCO₃ is an ergogenic strategy in conditions of high ambient heat.

摘要

本研究的目的是根据预先确定的个体达峰时间 (TTP) 血液碳酸氢盐 (HCO ₃ ^{− ) 探索个体化碳酸氢钠 (NaHCO} ₃ ) 补充剂对 4 公里自行车计时赛 (TT)的影响) 在高温下的表现。11 名经过娱乐训练的男性自行车手（年龄：28 ± 6 岁，身高：180 ± 6 厘米，体重：80.5 ± 8.4 千克）自愿参加这项随机、交叉、三盲、安慰剂对照设计的研究。在摄入 0.2 g.kg ⁻¹体重 (BM) NaHCO ₃后，进行了初步访问以确定 TTP HCO ₃ ⁻摄取。随后，在三个不同的场合，参与者在摄入 NaHCO ₃（0.2 g.kg ^-1体重）、氯化钠安慰剂（0.2 g.kg ⁻¹ BM；PLA）在预定的个体 TTP HCO ₃ ⁻或不补充（对照；CON）。与 PLA（+2.8 mmol.l ^-1；p  = 0.002；g  = 2.2）和 CON（+2.5 mmol.l ^{-1）相比，NaHCO} ₃在 4 公里循环之前的绝对峰值 [HCO ₃ ^- ] TT 升高；p  < 0.001；克 = 2.1）。_{NaHCO 3}后的完成时间比 PLA 快 5.6 ± 3.2 秒（1.6%；CI：2.8、8.3；p  = 0.001；g  = 0.2），比 CON 快 4.7 ± 2.8 秒（1.3%；CI：2.3、7.1；p  = 0.001；g  = 0.2）。这些结果表明，在预先建立的个人 TTP HCO ₃ ^-下摄入NaHCO ₃可以提高 4 公里循环 TT 在高温下的性能，这可能是通过提高缓冲能力来实现的。

强调

• 这是首次证明摄入 NaHCO ₃可提高高温环境下 4 公里循环 TT 性能。

• 较小剂量的 NaHCO ₃ (0.2 g.kg ⁻¹ BM) 在高温下具有增效作用，这小于通常为运动表现而摄入的剂量 (0.3 g.kg ⁻¹ BM)。这很重要，因为胃肠道不适通常随着剂量的减少而降低。

• _{这项研究表明，个体化的 HCO 3}峰值时间摄入策略和较低剂量的 NaHCO _{3是高环境}^热条件下的增效策略。