VO2max Training

Mechanisms:

• Maximal oxygen uptake (VO2max) reflects the integrated function of heart, lungs, blood, and muscles
• High-intensity intervals stress the cardiovascular system at near-maximum capacity
• Triggers cardiac remodeling - increased stroke volume and cardiac output
• Improves mitochondrial density and oxygen extraction in muscles
• Stimulates BDNF release for brain health and neuroplasticity

Key concepts:

• VO2max = maximum rate your body can use oxygen during exercise
• Measured in ml/kg/min - elite athletes hit 70-85, average adults 30-40
• Declines ~1% per year after 30 without training, but highly reversible
• "Cardiorespiratory fitness" and VO2max are often used interchangeably
• Training at 90-95% max HR is the sweet spot for adaptation

Evidence base:

• Mandsager 2018: Moving from low to above-average fitness = 5x reduction in mortality risk
• Multiple RCTs show 4x4 intervals improve VO2max more than moderate continuous training
• Norwegian studies demonstrate benefits even in cardiac patients and elderly
• BDNF increases acutely after high-intensity exercise
• Meta-analyses confirm superior VO2max gains from intervals vs steady-state

Limitations:

• Requires baseline fitness - not for complete beginners
• Higher injury risk than low-intensity training
• Needs adequate recovery between sessions
• Max HR formulas are imprecise - individual variation matters
• Diminishing returns at elite fitness levels

Getting started:

1. Establish baseline fitness - Should be able to do 20-30 min moderate cardio comfortably
2. Find your max heart rate - 220-age is rough; better to find it during a hard effort
3. Choose your modality - Running, cycling, rowing, stairs, or any cardio that lets you go hard
4. Start with one session per week - Add second session only after 4-6 weeks
5. Don't skip warmup - 5-10 min easy effort before intervals

The 4x4 Norwegian Protocol (gold standard):

• 10 min warmup at easy pace
• 4 minutes at 90-95% max HR (hard but sustainable - can say a few words)
• 3 minutes active recovery at 60-70% max HR (easy pace, keep moving)
• Repeat 4 times (total: 28 min of work)
• 5 min cooldown
• Frequency: 1-2x per week, never consecutive days

Alternative protocols:

• Tabata (advanced): 20 sec all-out / 10 sec rest, 8 rounds. Brutal but time-efficient.
• 10-20-30: 30 sec easy / 20 sec moderate / 10 sec sprint, repeat 5x, rest 2 min, do 3-4 blocks.
• 30/30s: 30 sec hard / 30 sec easy, 10-20 rounds. Good stepping stone to 4x4.

Progression:

• Week 1-2: 3x4 min intervals (build tolerance)
• Week 3-4: 4x4 min intervals
• Week 5+: Increase intensity before adding volume
• Advanced: 5x4 min or steeper hills/resistance

Risks:

• Cardiovascular events in those with undiagnosed heart conditions
• Musculoskeletal injury from high-force efforts
• Overtraining if combined with too much other intense exercise
• Nausea, dizziness during or after sessions (normal initially)
• Burnout if done too frequently

Contraindications - get medical clearance first if:

• Known heart disease or cardiovascular conditions
• High blood pressure (uncontrolled)
• Over 45 (men) or 55 (women) and sedentary
• Family history of sudden cardiac death
• Chest pain, shortness of breath, or dizziness with exertion
• Joint or orthopedic issues that limit high-intensity movement

Warning signs to stop immediately:

• Chest pain or pressure
• Severe shortness of breath beyond normal exertion
• Dizziness or lightheadedness
• Irregular heartbeat
• Pain (not discomfort) in joints or muscles

How to minimize risk:

• Get cardiac screening if risk factors present
• Build aerobic base first (Zone 2) before adding high intensity
• Always warm up thoroughly
• Use RPE (perceived exertion) alongside heart rate
• One hard session per week is enough for most people
• Full recovery between sessions (48-72 hours minimum)

Key metrics:

• Max heart rate achieved during intervals
• Time in 90-95% HR zone
• Recovery heart rate (how fast HR drops after effort)
• Perceived exertion (RPE 8-9 out of 10 during work intervals)
• Session completion (did you finish all intervals?)

Signs it's working:

• Lower heart rate at same running/cycling pace
• Faster recovery between intervals
• Can sustain higher power/speed at same HR
• Everyday activities feel easier
• Resting heart rate trends down over weeks
• VO2max estimate improves (if using wearable)

Timeline:

• Week 1-2: Sessions feel brutal, may not complete all intervals
• Week 3-4: Adapting, can finish sessions
• Week 6-8: Noticeable fitness improvement
• Week 12+: Measurable VO2max gains (5-15% typical)

No specific brands required - this is equipment-agnostic. A hill and a watch are enough.

Equipment options:

• Minimal: Running shoes, stairs, or hill
• Heart rate monitor: Polar H10 chest strap (most accurate) or optical watch
• Cardio machines: Rower, assault bike, spin bike, treadmill all work

Tracking tools:

• Any GPS watch with HR (Garmin, Apple Watch, WHOOP, Polar)
• Strava or TrainingPeaks for logging
• VO2max estimates from Garmin/Apple (directional, not precise)
• Professional VO2max test for baseline ($100-200)

Key voices:

• Peter Attia - Frames VO2max as the most important longevity metric
• Andrew Huberman - Covers HIIT protocols and cardiovascular health
• Martin Gibala, PhD - McMaster researcher, leading scientist on interval training
• Iñigo San-Millán - Discusses VO2max alongside Zone 2

Online communities:

• r/HIIT - Interval training discussion
• r/running - VO2max improvement threads
• Strava clubs focused on interval training

Common positive reports:

• "Best ROI on time for fitness"
• "Finally improved my VO2max after years of just running"
• "One session a week changed my cardio"
• "Paired with Zone 2 is the perfect combo"

Common complaints:

• "Sessions are brutal"
• "Hard to push myself without a group"
• "Took weeks to stop dreading it"
• "Easy to overdo and burn out"

Pairs well with:

• Zone 2 Cardio - Complementary; Zone 2 builds base, VO2max training builds peak. Do both.
• HRV Training - Use HRV to time high-intensity sessions (go hard when recovered)
• Creatine - May support repeated sprint performance
• Cold Exposure - Some use post-workout; avoid immediately after if prioritizing adaptation

Programming:

• Ideal week: 2-3 Zone 2 sessions + 1 VO2max session
• Don't do VO2max day after heavy leg training
• Allow 48-72 hours before next intense session

Stacks with:

• Endurance training programs
• Longevity protocols
• Cognitive enhancement (via BDNF)