Training methods to improve VO2max: A systematic review

Abstract

<h2>Abstract</h2> <p>Maximal oxygen uptake (VO2max) is the gold-standard measure of cardiorespiratory fitness and a powerful independent predictor of cardiovascular disease risk, all-cause mortality, and athletic performance across virtually all endurance sports. This <a href="/terms/systematic-review/" class="term-link" data-slug="systematic-review" title="systematic review">systematic review</a> by Buchheit and Laursen (2013) evaluates the evidence for various training methods to improve VO2max, examining the relative efficacy of long-interval <a href="/terms/hiit/" class="term-link" data-slug="hiit" title="HIIT">HIIT</a>, short-interval HIIT, sprint interval training, threshold training, and moderate-intensity continuous training across different population groups.</p> <p>The review concludes that long-interval HIIT (2–5 minute intervals at 90–100% VO2max) consistently produces the largest VO2max improvements in both untrained and trained populations, primarily through central cardiovascular adaptations including increased cardiac output and stroke volume. The optimal protocol for most individuals, backed by the strongest evidence, is the 4×4-minute format at 90–95% HRmax with 3-minute <a href="/terms/active-recovery/" class="term-link" data-slug="active-recovery" title="active recovery">active recovery</a>. Threshold training and moderate-intensity continuous training produce meaningful VO2max improvements in untrained individuals but show diminishing returns in trained populations relative to interval approaches. Training history is the most important moderating variable: untrained individuals improve VO2max with any sufficiently intense aerobic stimulus, while trained athletes require higher absolute intensities and greater time spent at near-maximal heart rates to achieve continued adaptation.</p> <p><em>Keywords: VO2max, maximal oxygen uptake, interval training, cardiac output, stroke volume, aerobic fitness</em></p>

Introduction

<h2>Introduction</h2> <p>VO2max, the maximum rate of oxygen consumption achievable during exhaustive whole-body exercise, has occupied a central position in exercise physiology for nearly a century. First systematically studied by A.V. Hill in the 1920s, VO2max is now established as both the principal determinant of endurance performance and a potent marker of physiological aging and disease risk [1]. The ability to predict cardiovascular mortality from VO2max measurements rivals or exceeds that of traditional risk factors including blood pressure, cholesterol, BMI, and smoking status in large prospective studies.</p> <p>Physiologically, VO2max is constrained at its upper limit by three interacting systems: oxygen delivery capacity (cardiac output), oxygen-carrying capacity of blood (hemoglobin concentration and blood volume), and peripheral oxygen extraction efficiency (skeletal muscle oxidative capacity). Training adaptations that increase any of these components will increase VO2max, but central cardiovascular adaptations (increased stroke volume) account for the majority of training-induced VO2max improvement in most population groups [2].</p> <p>The question of which training method most effectively improves VO2max is both scientifically contested and practically important. Moderate-intensity continuous training at 60–75% VO2max forms the basis of most public health exercise recommendations and produces the aerobic base necessary for sustainable training programs. <a href="/terms/hiit/" class="term-link" data-slug="hiit" title="High-intensity interval training">High-intensity interval training</a> at various intensities (85–130% VO2max) produces greater time-unit efficiency of VO2max improvement but requires greater recovery, carries higher injury risk, and demands greater psychological tolerance for discomfort [3].</p> <p>Understanding the <a href="/terms/dose-response-relationship/" class="term-link" data-slug="dose-response-relationship" title="dose-response relationship">dose-response relationship</a> between training intensity, volume, and VO2max improvement is essential for both clinical and performance applications. Cardiologists need to know which exercise prescriptions most efficiently improve fitness in cardiac rehabilitation. Coaches need to know which interval formats produce peak athletic performance for their athletes. Recreational fitness enthusiasts need guidance on balancing VO2max improvement with practical time constraints and recovery demands [4].</p> <p>Buchheit and Laursen's comprehensive review addresses these questions through systematic analysis of controlled training studies, examining how protocol design variables including interval duration, intensity, <a href="/terms/inter-set-rest-interval/" class="term-link" data-slug="inter-set-rest-interval" title="rest interval">rest interval</a> characteristics, and session frequency interact to determine VO2max adaptation magnitude and time course.</p>

Evidence Review

<h2>Evidence Review</h2> <h3>The Physiology of VO2max Improvement</h3> <p>VO2max improvement requires adaptations in the Fick equation components:</p> <p><strong>VO2max = Cardiac Output × Arteriovenous O2 difference</strong></p> <p>where Cardiac Output = Heart Rate × Stroke Volume</p> <p>Training-induced increases in stroke volume (the primary driver in most populations) occur through: 1. Increased plasma volume and total blood volume (occurs within 1–2 weeks) 2. Cardiac chamber enlargement (eccentric <a href="/terms/muscle-hypertrophy/" class="term-link" data-slug="muscle-hypertrophy" title="hypertrophy">hypertrophy</a>, occurs over weeks to months) 3. Improved left ventricular filling and ejection fraction 4. Enhanced autonomic tone (parasympathetic dominance at rest, increased sympathetic responsiveness during exercise)</p> <p>The peripheral components (arteriovenous O2 difference, reflecting skeletal muscle oxygen extraction) respond primarily to chronic low-intensity training that increases muscle capillary density and mitochondrial content [5].</p> <h3>Evidence by Training Method</h3> <p><strong>Moderate-Intensity Continuous Training (MICT, 60–75% VO2max)</strong></p> <ul> <li>VO2max improvement: +8–15% over 12 weeks (untrained), +2–5% (trained)</li> <li>Time required: 30–60 min/session, 5 sessions/week</li> <li>Primary mechanism: Peripheral adaptations, moderate cardiac adaptation</li> <li>Best for: Beginners building aerobic base; clinical populations</li> </ul> <p><strong>Threshold Training (75–85% VO2max, 20–40 min continuous)</strong></p> <ul> <li>VO2max improvement: +6–12% over 8–12 weeks (untrained), +3–6% (moderately trained)</li> <li>Time required: 20–40 min/session, 3–4 sessions/week</li> <li>Primary mechanism: Lactate threshold elevation; moderate central adaptations</li> <li>Best for: Intermediate athletes; base-building phase</li> </ul> <p><strong>Long-Interval <a href="/terms/hiit/" class="term-link" data-slug="hiit" title="HIIT">HIIT</a> (90–100% VO2max, 2–5 min intervals)</strong></p> <ul> <li>VO2max improvement: +7–10% over 8 weeks (trained); up to +15% (untrained)</li> <li>Time required: 35–45 min total (including warm-up/recovery), 2–3 sessions/week</li> <li>Primary mechanism: Maximal cardiac output stress; central adaptations dominant</li> <li>Best for: All populations seeking VO2max improvement efficiency [6]</li> </ul> <p><strong>Short-Interval HIIT (100–120% VO2max, 15–60 sec intervals)</strong></p> <ul> <li>VO2max improvement: +5–8% over 6–8 weeks</li> <li>High time-at-VO2max per session, lower absolute intensity demands</li> <li>Better tolerated by beginners than long-interval formats</li> </ul> <p><strong>Sprint Interval Training (120% VO2max, 10–30 sec all-out)</strong></p> <ul> <li>VO2max improvement: +5–9% over 6 weeks (untrained)</li> <li>Primarily peripheral (mitochondrial) adaptations</li> <li>Less effective for VO2max specifically than long-interval HIIT [7]</li> </ul> <h3>Protocol Comparison Summary</h3> <table> <thead> <tr> <th>Method</th> <th>VO2max Gain (8–12 weeks)</th> <th>Session Duration</th> <th>Frequency</th> <th>Best Population</th> </tr> </thead> <tbody> <tr> <td>MICT</td> <td>+8–15% (untrained)</td> <td>30–60 min</td> <td>5×/week</td> <td>Beginners</td> </tr> <tr> <td>Threshold</td> <td>+6–12% (untrained)</td> <td>20–40 min</td> <td>3–4×/week</td> <td>Intermediate</td> </tr> <tr> <td>Long-interval HIIT</td> <td>+7–15%</td> <td>35–45 min total</td> <td>2–3×/week</td> <td>All</td> </tr> <tr> <td>Short-interval HIIT</td> <td>+5–8%</td> <td>25–35 min total</td> <td>2–3×/week</td> <td>All</td> </tr> <tr> <td>SIT</td> <td>+5–9% (untrained)</td> <td>20–30 min total</td> <td>2–3×/week</td> <td>Fit, motivated</td> </tr> </tbody> </table>

Discussion

<h2>Discussion</h2> <h3>Why Long-Interval <a href="/terms/hiit/" class="term-link" data-slug="hiit" title="HIIT">HIIT</a> Dominates VO2max Improvement</h3> <p>The consistent superiority of long-interval HIIT (2–5 minute intervals at 90–100% VO2max) for VO2max improvement stems from its uniquely effective stimulus on cardiac output. To improve VO2max, the heart must be regularly stressed near its maximal pumping capacity. Short bursts (SIT, 30-second sprints) activate the cardiovascular system but do not sustain near-maximal cardiac output long enough per interval to produce optimal cardiac remodeling. Long intervals at 90–95% HRmax achieve and sustain near-maximal cardiac output for 3–4 minutes per interval, accumulating 12–20 minutes of "effective" cardiovascular stimulus per session [8].</p> <p>This insight explains the repeatedly validated superiority of the 4×4-minute protocol. It maximizes the cumulative time near VO2max (approximately 15–18 minutes when including the final 1–2 minutes of each interval where VO2 reaches maximal) while being achievable for most individuals with reasonable fitness and providing sufficient recovery (3 minutes active) between efforts to maintain quality.</p> <h3>The Training History Effect</h3> <p>One of the most practically important findings is how training history determines optimal protocol selection. VO2max improvement in untrained individuals is essentially training-method-agnostic: any regularly performed aerobic exercise above 60% VO2max will produce substantial VO2max improvements over 8–12 weeks. This is because untrained individuals have so much adaptive capacity in peripheral oxygen utilization that even modest cardiovascular stimuli are sufficient [9].</p> <p>As training status improves, the VO2max response becomes increasingly dependent on intensity. Moderately trained individuals (VO2max 45–55 ml/kg/min) respond best to threshold training and short-interval HIIT. Highly trained individuals (VO2max 55 ml/kg/min) typically require long-interval HIIT at 90–95% VO2max to continue improving, as their peripheral adaptations are nearly maximal and further improvement depends on central cardiovascular change [10].</p> <h3>VO2max as a Health Metric</h3> <p>Beyond athletic performance, VO2max is one of the most powerful predictors of longevity in general populations. The relationship between VO2max and all-cause mortality is continuous, with each 1 MET (3.5 ml/kg/min) improvement in aerobic capacity associated with approximately 13–15% reduction in mortality risk [11]. This effect is independent of age, sex, weight, and other risk factors, and is observed even in populations with established cardiovascular disease.</p> <p>From a public health perspective, the absolute improvement in VO2max is less important than moving individuals from the lowest fitness quintile (VO2max 25 ml/kg/min) to more moderate fitness levels (35 ml/kg/min). The mortality risk reduction from this transition (approximately 45–50%) far exceeds any exercise-induced improvement achievable within the elite fitness range [12].</p> <h3>Interaction with Resistance Training and Recovery</h3> <p>VO2max-focused training sessions generate substantial cardiovascular stress and cannot be performed at peak quality when residual fatigue from resistance training is present. Heavy lower-body lifting (squats, deadlifts) the day before a 4×4 interval session reliably reduces interval performance, as the quadriceps and hip extensors are the primary force-generating muscles during cycling and running intervals [13]. Programming VO2max interval sessions on days separate from heavy lower-body resistance training optimizes both adaptation stimuli.</p>

Practical Recommendations

<h2>Practical Recommendations</h2> <h3>Estimating Your Current VO2max</h3> <p>Without laboratory testing, use these field estimates:</p> <table> <thead> <tr> <th>Method</th> <th>Protocol</th> <th>VO2max Estimate Formula</th> </tr> </thead> <tbody> <tr> <td>1.5-mile (2.4km) run</td> <td>Run 1.5 miles as fast as possible</td> <td>Use online calculators with time + HR</td> </tr> <tr> <td>Cooper 12-minute run</td> <td>Run as far as possible in 12 min</td> <td>(Distance in meters − 504.9) ÷ 44.73</td> </tr> <tr> <td>Beep test</td> <td>Progressive shuttle run</td> <td>Use beep test VO2max tables</td> </tr> <tr> <td>Resting HR estimate</td> <td>Measure morning resting HR</td> <td>VO2max ≈ 15 × (HRmax/HRrest)</td> </tr> </tbody> </table> <p>HRmax can be estimated as 220 minus age (±10 bpm individual variation).</p> <h3>Protocol Selection by Training Status</h3> <p><strong>Beginners (VO2max 35 ml/kg/min, less than 6 months aerobic training):</strong> - Start with 3–4 weeks of 30-minute easy aerobic sessions (Zone 1–2) before introducing intervals - Begin intervals with short-interval format: 10 × 1-minute at 85–90% HRmax, 1-minute rest - Progress to long-interval format after 4–6 weeks of short-interval adaptation</p> <p><strong>Intermediate (VO2max 35–50 ml/kg/min, 6 months to 3 years training):</strong> - 4×4-minute protocol at 90–95% HRmax, 2×/week - Supplement with 1 longer Zone 2 session per week (45–60 min)</p> <p><strong>Advanced (VO2max 50 ml/kg/min, 3 years structured training):</strong> - 4×4-minute protocol remains valid but may need to extend to 5×4 or 4×5 minutes - Intensities at 95–100% HRmax with passive rest intervals - Consider lactate testing to precisely identify individual threshold intensities</p> <h3>The 4×4 Protocol: Step-by-Step</h3> <ol> <li><strong>Warm-up</strong>: 10 minutes building from 50% to 75% HRmax</li> <li><strong>Interval 1</strong>: 4 minutes at 90–95% HRmax. HR should reach 90% within 90 seconds.</li> <li><strong>Recovery 1</strong>: 3 minutes at 60–70% HRmax (active cycling, jogging, or walking)</li> <li><strong>Intervals 2–4</strong>: Repeat interval and recovery pattern</li> <li><strong>Cool-down</strong>: 5–10 minutes easy</li> </ol> <p>Check: By the third or fourth interval, maintaining 90%+ HRmax for the full 4 minutes should be challenging but achievable. <a href="/terms/intermittent-fasting/" class="term-link" data-slug="intermittent-fasting" title="If">If</a> it is easy, the intensity is insufficient. If you cannot complete all 4 intervals at target HR, reduce the pace slightly in the first 2 intervals.</p> <h3>Frequency and <a href="/terms/periodization/" class="term-link" data-slug="periodization" title="Periodization">Periodization</a></h3> <ul> <li>Perform 2 interval sessions per week maximum during dedicated VO2max development phases</li> <li>Maintain at least 48 hours between interval sessions</li> <li>After 4–6 weeks of VO2max intervals, take a 1-week <a href="/terms/deload/" class="term-link" data-slug="deload" title="deload">deload</a> (reduce intensity/volume by 40–50%) before resuming to allow adaptation consolidation</li> <li>After 8–12 weeks of VO2max focus, shift to maintenance (1 interval session/week) while emphasizing other training goals</li> </ul>