Supplementation
Narrative Review
2016
Sodium bicarbonate supplementation and exercise performance: An update
By Lars R. McNaughton and Bryan Saunders
Journal of the International Society of Sports Nutrition, 13(1), pp. 1-13
<h2>Abstract</h2>
<p>This review by McNaughton and Saunders (2016) synthesizes the contemporary evidence on sodium bicarbonate (NaHCO₃) as an <a href="/terms/ergogenic-aid/" class="term-link" data-slug="ergogenic-aid" title="ergogenic aid">ergogenic aid</a> for high-intensity exercise performance. Sodium bicarbonate's primary mechanism of action involves increasing extracellular buffering capacity, thereby facilitating the efflux of intracellular lactate and hydrogen ions during intense exercise, attenuating the drop in intramuscular pH that contributes to fatigue in glycolytic exercise of 30 seconds to approximately 12 minutes in duration.</p>
<p>The review concludes that sodium bicarbonate supplementation reliably improves performance in high-intensity intermittent and continuous exercise modalities, with effect sizes of moderate magnitude for events in the sensitive duration range [1]. Optimal dosing is established at 0.2-0.3g/kg body weight taken 60-90 minutes before exercise, a timing that aligns peak plasma bicarbonate elevation with the exercise bout. The most significant practical limitation is gastrointestinal (GI) distress, which occurs in a substantial proportion of users and can negate performance benefits <a href="/terms/intermittent-fasting/" class="term-link" data-slug="intermittent-fasting" title="if">if</a> sufficiently severe [2].</p>
<p>Individual variability in both performance response and GI tolerance is high, making personal dose-finding trials essential. Co-ingestion with carbohydrate-containing meals and split-dose strategies substantially mitigate GI side effects without compromising buffering efficacy.</p>
<p><strong>Keywords</strong>: sodium bicarbonate, bicarbonate loading, acid-base balance, extracellular buffering, high-intensity exercise, lactate, pH, ergogenic aid</p>
<h2>Introduction</h2>
<p>High-intensity exercise is metabolically characterized by rapid glycolytic <a href="/terms/adenosine-triphosphate/" class="term-link" data-slug="adenosine-triphosphate" title="ATP">ATP</a> production, generating pyruvate faster than it can be oxidized in the mitochondria. Pyruvate is reduced to lactate — a reaction that simultaneously consumes a hydrogen ion (H⁺), but the net result of intense glycolysis is still a progressive decrease in intracellular pH. This intracellular acidosis impairs muscle contractile function through multiple mechanisms: inhibition of phosphofructokinase (a rate-limiting glycolytic enzyme), impaired calcium release from the sarcoplasmic reticulum, reduced cross-bridge cycling rate, and direct interference with actin-myosin interaction [1].</p>
<p>The hydrogen ion concentration gradient between the intracellular and extracellular compartments drives the export of H⁺ (co-transported with lactate) out of the <a href="/terms/muscle-fiber/" class="term-link" data-slug="muscle-fiber" title="muscle cell">muscle cell</a>, a process mediated by monocarboxylate transporters (MCT1 and MCT4). The capacity of the extracellular fluid to accept these exported H⁺ ions — its buffering capacity — limits how effectively intracellular pH can be maintained. The bicarbonate ion (HCO₃⁻) is the primary extracellular buffer: HCO₃⁻ + H⁺ → H₂CO₃ → H₂O + CO₂, with CO₂ expelled via ventilation [2].</p>
<p>This biochemical cascade suggests a clear intervention point: <a href="/terms/intermittent-fasting/" class="term-link" data-slug="intermittent-fasting" title="if">if</a> plasma bicarbonate concentration can be elevated before exercise begins, the extracellular buffering reserve will be expanded, delaying the intracellular pH decline that contributes to fatigue. This is the mechanistic foundation of sodium bicarbonate (NaHCO₃) as an ergogenic supplement — a concept that has been studied in exercise physiology since the 1930s, making it one of the longest-studied of all performance supplements.</p>
<p>Sodium bicarbonate is distinguished from <a href="/terms/beta-alanine/" class="term-link" data-slug="beta-alanine" title="beta-alanine">beta-alanine</a> (which elevates intracellular carnosine, an intracellular buffer) as an extracellular buffering strategy. The two operate on different compartments and are potentially complementary. Understanding this compartmental specificity is important for predicting which exercise modalities benefit most: the extracellular buffering mechanism is most relevant for activities intense enough to generate substantial glycolytic H⁺ production, yet short enough that the resulting acidosis is a primary performance-limiting factor — roughly the 30-second to 12-minute range [3].</p>
<p>Resistance training represents a relevant but under-studied application. Multiple sets of high-repetition work (15-30 repetitions per set) generate the glycolytic stress that sodium bicarbonate should theoretically attenuate. Evidence from resistance exercise studies is more heterogeneous than from traditional endurance events, in part due to the complex, intermittent nature of the training stress [4].</p>
<h2>Evidence Review</h2>
<h3>Swimming and Rowing (High-Sensitivity Modalities)</h3>
<p>The strongest and most consistent evidence for sodium bicarbonate performance benefits comes from swimming and rowing events — high-intensity, sustained efforts of 1-4 minutes that precisely match the sensitive duration window for glycolytic H⁺ accumulation. A <a href="/terms/meta-analysis/" class="term-link" data-slug="meta-analysis" title="meta-analysis">meta-analysis</a> of 23 trials in swimmers found a mean performance improvement of 1.5-2% in 100-400m events, with smaller but consistent effects observed in 50m events [1].</p>
<p>Rowing events of 2000m (approximately 6-8 minutes) show similar consistent improvements with sodium bicarbonate, with studies reporting 1-3% reductions in race time that translate to meaningful competitive advantages at the elite level.</p>
<h3>Track Cycling and Sprint Performance</h3>
<p>Repeated 30-second to 60-second maximal cycling efforts — conditions that maximally stress the phosphagen-glycolytic interface — show consistent sodium bicarbonate benefits. Key findings from controlled trials:</p>
<table>
<thead>
<tr>
<th>Study Type</th>
<th>Exercise Mode</th>
<th>Dose</th>
<th>Performance Effect</th>
</tr>
</thead>
<tbody>
<tr>
<td>Controlled trial</td>
<td>Single 60s sprint</td>
<td>0.3g/kg</td>
<td>+7% peak power, +5% mean power</td>
</tr>
<tr>
<td>Repeated sprint</td>
<td>5 × 30s cycling</td>
<td>0.3g/kg</td>
<td>+3-4% total work, better maintenance of power</td>
</tr>
<tr>
<td>Intermittent</td>
<td>4 × 1000m runs</td>
<td>0.3g/kg</td>
<td>Mean pace -2.1% faster</td>
</tr>
<tr>
<td>Resistance training</td>
<td>Multiple sets 20RM bench press</td>
<td>0.3g/kg</td>
<td>+2 reps per set in later sets</td>
</tr>
</tbody>
</table>
<h3>Resistance Training Evidence</h3>
<p>Evidence for sodium bicarbonate in resistance training is more heterogeneous than in cycling or swimming, partly because resistance training intermittent rest periods allow partial pH recovery between sets [2]. Studies that show benefits typically share these features:</p>
<ul>
<li><strong>High repetition work</strong> (15-30 repetitions per set): Greater glycolytic stress per set compared to heavier low-repetition training</li>
<li><strong>Shorter <a href="/terms/inter-set-rest-interval/" class="term-link" data-slug="inter-set-rest-interval" title="inter-set rest">inter-set rest</a> intervals</strong> (60-90 seconds): Insufficient time for complete pH recovery, allowing sodium bicarbonate's buffering reserve to attenuate cumulative acidosis</li>
<li><strong>Multiple sets to failure</strong>: Sodium bicarbonate's benefit tends to be most apparent in the later sets where fatigue compounds</li>
</ul>
<p>Studies using heavier loads (≤6-8 repetitions to failure with 3 minutes rest) generally show no significant sodium bicarbonate benefit — consistent with the expectation that neuromuscular and phosphagen fatigue, not glycolytic H⁺ accumulation, are primary limiters in this training modality.</p>
<h3><a href="/terms/dose-response-relationship/" class="term-link" data-slug="dose-response-relationship" title="Dose-Response">Dose-Response</a> and Timing</h3>
<p>The pharmacokinetics of oral sodium bicarbonate ingestion follow a predictable time course [3]:</p>
<table>
<thead>
<tr>
<th>Parameter</th>
<th>Value</th>
</tr>
</thead>
<tbody>
<tr>
<td>Time to peak plasma HCO₃⁻</td>
<td>60-90 minutes</td>
</tr>
<tr>
<td>Peak plasma HCO₃⁻ elevation</td>
<td>+5-6 mEq/L above baseline</td>
</tr>
<tr>
<td>Duration of peak elevation</td>
<td>30-60 minutes</td>
</tr>
<tr>
<td>Effective dose range</td>
<td>0.2-0.3g/kg body weight</td>
</tr>
<tr>
<td>Below-threshold dose</td>
<td>0.2g/kg (insufficient buffering reserve)</td>
</tr>
<tr>
<td>Above-ceiling dose</td>
<td>0.3g/kg (GI risk increases without performance gain)</td>
</tr>
</tbody>
</table>
<p>The 0.3g/kg dose is established as the standard in most research, but the 0.2g/kg dose provides meaningful buffering with substantially reduced GI risk — a useful starting dose for individuals with high GI sensitivity.</p>
<h2>Discussion</h2>
<h3>The GI Tolerance Problem</h3>
<p>Sodium bicarbonate's greatest practical limitation is gastrointestinal distress. When NaHCO₃ enters the acidic stomach environment, it reacts with hydrochloric acid: NaHCO₃ + HCl → NaCl + H₂O + CO₂. This CO₂ generation causes bloating, belching, nausea, and in some individuals abdominal cramping — effects that are not merely uncomfortable but can directly impair athletic performance [1].</p>
<p>Reported GI symptom rates vary considerably across studies (15-50% of subjects), suggesting substantial individual variability. Several evidence-based strategies mitigate GI distress without compromising the buffering effect:</p>
<ul>
<li><strong>Co-ingestion with food</strong>: Consuming sodium bicarbonate with a carbohydrate-rich meal slows gastric emptying, reduces the rate of CO₂ generation in the stomach, and has been shown to reduce GI symptoms while preserving bicarbonate absorption and plasma elevation</li>
<li><strong>Split dosing</strong>: Dividing the total dose into 3-4 smaller doses consumed over 30-60 minutes reduces the instantaneous acid-neutralization reaction in the stomach</li>
<li><strong>Sodium citrate as alternative</strong>: Sodium citrate has a similar alkalizing mechanism with substantially fewer GI side effects; however, peak plasma bicarbonate elevation is lower, and the performance evidence base is less extensive</li>
</ul>
<h3>Individual Variability in Performance Response</h3>
<p>Beyond GI tolerance, there is meaningful variability in the performance response to sodium bicarbonate — some athletes show dramatic improvements while others show minimal change at the same dose. Potential explanations include [2]:</p>
<ul>
<li><strong>Baseline buffering capacity</strong>: Athletes with naturally higher baseline plasma bicarbonate may have less room for meaningful elevation</li>
<li><strong>Training-induced acid-base adaptations</strong>: Well-trained endurance athletes develop superior lactate and H⁺ clearance mechanisms, potentially reducing the absolute magnitude of acidosis during standardized testing</li>
<li><strong>Exercise modality specificity</strong>: The match between the exercise duration/intensity profile and the sensitive window for glycolytic H⁺ accumulation determines how relevant extracellular buffering is for a given athlete</li>
<li><strong><a href="/terms/muscle-fiber/" class="term-link" data-slug="muscle-fiber" title="Muscle fiber">Muscle fiber</a> type composition</strong>: Athletes with high proportions of fast-twitch type II fibers generate more H⁺ per unit time during glycolytic exercise, theoretically making them more responsive to extracellular buffering augmentation</li>
</ul>
<h3>Comparison with <a href="/terms/beta-alanine/" class="term-link" data-slug="beta-alanine" title="Beta-Alanine">Beta-Alanine</a></h3>
<p>Sodium bicarbonate and beta-alanine are the two primary evidence-based buffering strategies in sports nutrition, targeting different compartments [3]:</p>
<table>
<thead>
<tr>
<th>Property</th>
<th>Sodium Bicarbonate</th>
<th>Beta-Alanine</th>
</tr>
</thead>
<tbody>
<tr>
<td>Buffer location</td>
<td>Extracellular (plasma)</td>
<td>Intracellular (carnosine)</td>
</tr>
<tr>
<td>Time course</td>
<td>Acute (single dose, 60-90 min pre-exercise)</td>
<td>Chronic (4-6 weeks supplementation)</td>
</tr>
<tr>
<td>Primary evidence</td>
<td>30s-12 min high-intensity events</td>
<td>Similar window, some evidence of synergy</td>
</tr>
<tr>
<td>GI concerns</td>
<td>Yes (CO₂ production)</td>
<td>Paresthesia (harmless tingling)</td>
</tr>
<tr>
<td>Combination evidence</td>
<td>Additive effects reported in some trials</td>
<td>—</td>
</tr>
</tbody>
</table>
<p>The complementary nature of these mechanisms makes combining sodium bicarbonate and beta-alanine a theoretically sound strategy, and some trials have reported additive performance benefits in repeated sprint and middle-distance events.</p>
<h3>Chronic vs. Acute Administration</h3>
<p>Most research has examined acute single-dose sodium bicarbonate protocols. A smaller body of evidence has examined chronic (daily multi-week) supplementation. Chronic protocols have the theoretical advantage of maintaining elevated plasma bicarbonate continuously, avoiding the timing challenge of acute protocols — but the evidence for superior performance outcomes is limited, and chronic use raises concerns about kidney bicarbonate regulation and rebound [4].</p>
<h2>Practical Recommendations</h2>
<h3>Who Benefits Most from Sodium Bicarbonate</h3>
<table>
<thead>
<tr>
<th>Scenario</th>
<th>Expected Benefit</th>
<th>Priority</th>
</tr>
</thead>
<tbody>
<tr>
<td>400m-1500m running events</td>
<td>Large (well-studied)</td>
<td>High</td>
</tr>
<tr>
<td>100-400m swimming events</td>
<td>Large (well-studied)</td>
<td>High</td>
</tr>
<tr>
<td>2000m rowing</td>
<td>Moderate-large</td>
<td>High</td>
</tr>
<tr>
<td>Repeated sprint sports (soccer, basketball)</td>
<td>Moderate</td>
<td>Moderate</td>
</tr>
<tr>
<td>High-rep resistance training (15-30 reps, short rest)</td>
<td>Small-moderate</td>
<td>Moderate</td>
</tr>
<tr>
<td>Heavy strength training (≤6RM, long rest)</td>
<td>Minimal</td>
<td>Low</td>
</tr>
<tr>
<td>Aerobic endurance events (15 min)</td>
<td>Small/negligible</td>
<td>Low</td>
</tr>
</tbody>
</table>
<h3>Standard Acute Dosing Protocol</h3>
<p><strong>Step 1: Determine body weight dose</strong>
- Standard dose: <strong>0.3g/kg body weight</strong> (e.g., 21g for a 70kg athlete)
- Conservative start for GI-sensitive individuals: <strong>0.2g/kg</strong> (14g for 70kg)</p>
<p><strong>Step 2: Timing</strong>
- Consume 60-90 minutes before exercise begins — this aligns peak plasma bicarbonate elevation with the exercise bout
- This timing window accounts for the ~60-90 minute absorption curve</p>
<p><strong>Step 3: Minimize GI risk</strong>
- Consume with a moderate-carbohydrate meal (oats, toast, rice) to slow gastric emptying
- Alternatively: divide dose into 3-4 equal portions consumed over 30-60 minutes
- Avoid high-fat or high-fiber meals around dosing (slow gastric emptying unpredictably)</p>
<p><strong>Step 4: Practice before competition</strong>
- Do not use sodium bicarbonate for the first time before a competition or important training session
- Individual GI tolerance and performance response vary — establish personal protocol in training [1]</p>
<h3>Combining with <a href="/terms/beta-alanine/" class="term-link" data-slug="beta-alanine" title="Beta-Alanine">Beta-Alanine</a></h3>
<p>For athletes competing in events where this combination is appropriate (middle-distance, repeated sprints, high-rep resistance training):</p>
<ul>
<li><strong>Beta-alanine</strong>: 3.2-6.4g/day in divided doses, taken chronically for 4-6 weeks to saturate muscle carnosine</li>
<li><strong>Sodium bicarbonate</strong>: 0.3g/kg acutely, 60-90 minutes before the performance event</li>
<li>Some trials show additive effects when both are used together — the intracellular and extracellular buffering systems are complementary</li>
</ul>
<h3>Resistance Training Application</h3>
<p>Sodium bicarbonate is most applicable to resistance training scenarios with these characteristics:</p>
<ul>
<li><strong>High repetition ranges</strong> (15-30 reps per set)</li>
<li><strong>Short rest intervals</strong> (60-90 seconds between sets)</li>
<li><strong>Multiple sets of a muscle group</strong> to failure or near-failure</li>
<li><strong>Metabolic conditioning</strong> protocols (circuit training, complexes)</li>
</ul>
<p>For traditional strength training (3-5RM, 3-5 minute rest), sodium bicarbonate is unlikely to provide meaningful benefit and the GI risk does not justify use.</p>
<h3>Practical Resistance Training Protocol</h3>
<p>For a high-rep <a href="/terms/muscle-hypertrophy/" class="term-link" data-slug="muscle-hypertrophy" title="hypertrophy">hypertrophy</a> session where sodium bicarbonate is being trialed:</p>
<ol>
<li>Consume 0.3g/kg NaHCO₃ with a moderate-carbohydrate meal (e.g., oats with banana) 75-90 minutes before the session</li>
<li>Train with 15-20 rep ranges across 4-5 sets per muscle group with 60-90 second rest periods</li>
<li>Track reps completed in the final sets compared to baseline (the benefit should appear as better maintenance of rep performance in the later sets of each exercise)</li>
</ol>
<h3>Sodium Citrate Alternative</h3>
<p>For individuals who experience significant GI distress with sodium bicarbonate despite split dosing and food co-ingestion, sodium citrate (0.5g/kg, similar timing) provides an alkalizing effect through a different mechanism with fewer GI side effects. The performance evidence base is smaller, but some trials report comparable benefits [2].</p>
<h3>Safety Notes</h3>
<p>At recommended doses (0.2-0.3g/kg), sodium bicarbonate has an excellent short-term safety profile. Concerns are primarily practical (GI distress) rather than physiological. Individuals with hypertension, kidney disease, or sodium-restricted diets should consult a physician before use, given the sodium load — a standard 0.3g/kg dose for a 70kg athlete delivers approximately 600mg of sodium [3].</p>