Effects of Acute Alkalosis and Acidosis on Performance

Abstract

Ingestion of agents that modify blood buffering action may affect high-intensity performance. Here we present a meta-analysis of the effects of acute ingestion of three such agents - sodium bicarbonate, sodium citrate and ammonium chloride - on performance and related physiological variables (blood bicarbonate, pH and lactate). A literature search yielded 59 useable studies with 188 observations of performance effects. To perform the mixed-model meta-analysis, all performance effects were converted into a percentage change in mean power and were weighted using standard errors derived from exact p-values, confidence limits (CLs) or estimated errors of measurement. The fixed effects in the meta-analytic model included the number of performance-test bouts (linear), test duration (log linear), blinding (yes/no), competitive status (athlete/nonathlete) and sex (male/female). Dose expressed as buffering mmoL/kg/body mass (BM) was included as a strictly proportional linear effect interacted with all effects except blinding. Probabilistic inferences were derived with reference to thresholds for small and moderate effects on performance of 0.5% and 1.5%, respectively. Publication bias was reduced by excluding study estimates with a standard error >2.7%. The remaining 38 studies and 137 estimates for sodium bicarbonate produced a possibly moderate performance enhancement of 1.7% (90% CL ± 2.0%) with a typical dose of 3.5 mmoL/kg/BM (∼0.3 g/kg/BM) in a single 1-minute sprint, following blinded consumption by male athletes. In the 16 studies and 45 estimates for sodium citrate, a typical dose of 1.5 mmoL/kg/BM (∼0.5 g/kg/BM) had an unclear effect on performance of 0.0% (±1.3%), while the five studies and six estimates for ammonium chloride produced a possibly moderate impairment of 1.6% (±1.9%) with a typical dose of 5.5 mmoL/kg/BM (∼0.3 g/kg/BM). Study and subject characteristics had the following modifying small effects on the enhancement of performance with sodium bicarbonate: an increase of 0.5% (±0.6%) with a 1 mmoL/kg/BM increase in dose; an increase of 0.6% (±0.4%) with five extra sprint bouts; a reduction of 0.6% (±0.9%) for each 10-fold increase in test duration (e.g. 1-10 minutes); reductions of 1.1% (±1.1%) with nonathletes and 0.7% (±1.4%) with females. Unexplained variation in effects between research settings was typically ±1.2%. The only noteworthy effects involving physiological variables were a small correlation between performance and pre-exercise increase in blood bicarbonate with sodium bicarbonate ingestion, and a very large correlation between the increase in blood bicarbonate and time between sodium citrate ingestion and exercise. The approximate equal and opposite effects of sodium bicarbonate and ammonium chloride are consistent with direct performance effects of pH, but sodium citrate appears to have some additional metabolic inhibitory effect. Important future research includes studies of sodium citrate ingestion several hours before exercise and quantification of gastrointestinal symptoms with sod...

Single and Combined Effects of Beetroot Crystals and Sodium Bicarbonate on 4-km Cycling Time Trial Performance

“…NaHCO 3 loading can enhance the performance of laboratory-based cycling (4-min TT; Bellinger et al, 2012; 3-km TT; Kilding et al, 2012), and other laboratory or field protocols of similar duration and intensity (e.g., 2000-m rowing ergometer TT (Hobson et al, 2014); 1500-m running (Bird et al, 1995)). Indeed, a metaanalysis of NaHCO 3 loading and sports performance found a possibly moderate enhancement of 1.7% (90% CL ± 2.0%) in a 1-min sprint following blinded consumption of 0.3 g·kg -1 BM NaHCO 3 by male athletes that is reduced with each 10-fold increase in test duration by 0.6% (±0.9%) (Carr et al, 2011a). Increases in preexercise blood were identified as a determinant of performance benefits.…”

“…NO's effects on physiological functions such as blood flow, muscle oxidative metabolism and mitochondrial biogenesis (Lee et al, 2015;Vaughan et al, 2016) may contribute to observations of improved athletic performance, particularly in shorter, high-intensity activities (De Smet et al, 2016;Lansley et al, 2011). Meanwhile, several studies report a modest benefit of the alkalizing agent NaHCO 3 on the performance of high-intensity exercise (Kilding et al, 2012) via an increased capacity to buffer hydrogen ions (H + ) produced by anaerobic glycolysis (Carr et al, 2011a).…”

New strategies in sport nutrition to increase exercise performance

“…A comprehensive meta-analysis of the lengthy history of bicarbonate supplementation and sports performance found a moderate (1.7 ± 2.0%, 90%CL) enhancement of a single 1-minute sprint in male athletes with the typical protocol [134]. This increases by ~0.5% (±0.5%) with a larger (+0.1 mg/kg) dose or five extra sprint bouts, and reduces by a similar magnitude with each 10-fold increase in test duration (e.g.…”

β–alanine: performance effects, usage and side effects

“…There was a significant elevation in blood bicarbonate (4.67 -5.75 mmol·L -1 ) from baseline, which is in line with the mean increase of 5.30 mmol·L -1 previously reported in a meta-analysis using the same 0.3 g·kgBM -1 dose [249] and greater than the average increase (3.9 mmol·L -1 ) reported in a more recent meta-analysis by Carr et al [17]. Similarly, there was an increase in blood pH and base excess following acute NaHCO3 supplementation, hence circulatory alkalosis had occurred and this is in agreement with previous studies that used similar dosing protocols [224,[250][251][252][253].…”

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