Dr. Andy Galpin is not an influencer who got interested in fitness. He's a professor of kinesiology at California State University who trains professional fighters, world champion athletes, and Special Forces operators. When he talks about VO2max, he's coming from a place of both deep research and practical coaching experience.
His take isn't gentle: VO2max, he says, is two to four times better at predicting all-cause mortality than blood pressure, smoking history, or cholesterol. Not slightly better. Multiples better.
If that doesn't motivate you to care about this number, nothing will.
The Core Concept: Your Aerobic Engine
Galpin breaks down VO2max using what exercise scientists call the Modified Fick Equation. Don't let the name scare you — it's actually a beautifully simple idea:
VO2max = Cardiac Output × Oxygen Extraction
Or, in human terms:
VO2max = (Heart Rate × Stroke Volume) × How Well Muscles Pull Oxygen from Blood
- Heart Rate: how many times your heart beats per minute at max effort
- Stroke Volume: how much blood your heart ejects with each beat
- Oxygen Extraction (AVO2 difference): how efficiently your muscles strip oxygen from the blood flowing through them
Training improves all three components. Your heart gets stronger and pumps more blood per beat. Your muscles grow more mitochondria (the tiny organelles inside cells that burn oxygen to make energy — think of them as the power plants). And your blood vessels become more efficient at delivering and exchanging oxygen.
This is why cardiovascular fitness improves so dramatically with training, and why it deteriorates so quickly without it.
The Four Training Zones (Galpin's Framework)
Galpin uses a four-zone intensity system, and understanding these zones is the foundation of everything that follows:
Zone 1 — Easy/Blue (60–65% max HR) This feels embarrassingly easy. You could sing if you wanted to. Nasal breathing is comfortable. Most people never go this easy on their "easy" days — and that's a mistake.
Zone 2 — Moderate/Green (65–85% max HR) Steady, sustainable, moderate effort. You can talk but wouldn't want to. This is where tempo work lives.
Zone 3 — Hard/Red (85%+ max HR) Your cardiovascular system is working hard. Short conversations only. This is interval territory.
Zone 4 — Infrared (95%+ max HR) Near-maximal. All-out. You can sustain this for seconds to minutes, not longer.
A critical insight from Galpin (and elite sport science more broadly): most recreational athletes spend too much time in Zone 2, not enough in Zone 1, and not enough in Zone 4. The grey zone in the middle produces mediocre adaptation. Polarized training — genuinely easy or genuinely hard — produces better results.
Joel Jameson's Metamorphosis Protocol
Galpin recommends an eight-week program from conditioning coach Joel Jameson — a man who has trained world champions in combat sports and whose methods are backed by extensive evidence. Galpin walks through the full protocol in a video that covers everything from training theory to practical implementation.
Here's how it works:
Weeks 1–4: Foundation Phase (5 days/week)
Easy Days:
- Start with a 5-minute warm-up: ankle rolls, hip mobility (windshield wipers), goblet squats
- 2–3 minutes of low-level aerobic plyometrics: light jump rope, small hops — this builds tissue tolerance in the ankles and Achilles tendon without demanding recovery
- 15–20 minutes of steady-state cardio at ~60–65% max HR — nasal breathing only
- Then optional light strength work (upper body press/pull, 2–3 sets each)
- Cool-down: 3–6 minutes of slow breathing (long exhales to activate parasympathetic recovery)
The nasal-breathing rule is Galpin's built-in intensity governor. If you can't breathe comfortably through your nose, you're going too hard. Simple and self-correcting.
Moderate Days:
- Same warm-up as easy days
- Tempo intervals: 10–15 seconds of elevated effort (a noticeable increase, not all-out) followed by 45–60 seconds of lower-intensity movement — continuously, for 8–10 cycles
- This teaches your system to handle small surges and recover without stopping
Progression: Each week, add slightly more volume or duration — but never more than ~10% total increase. Small weekly additions compound into big changes; aggressive jumps cause injuries.
Weeks 5–8: Power Phase (6 days/week)
Add a "hard day" to the rotation:
Hard Day — Power Intervals:
- 5–10 seconds of genuinely maximal effort
- 40–120 seconds of easy recovery (1:5 to 1:12 work-to-rest ratio)
- 8–10 repetitions
The key word is genuinely. Not "harder than moderate." Actually all-out. Peak power output is what drives the adaptation. If you're pacing yourself to survive the set, you're underdoing it.
Moderate Day — Repeats (new addition):
- 30–60 second efforts at 80–85% max HR
- Equal rest (so 30 sec on = 30 sec off)
- 10 repetitions total
This is harder than the tempo intervals from weeks 1–4 but not maximal — it develops your ability to sustain higher intensities for longer.
The Cooper Test: Measure Everything
At the end of week 8, Galpin recommends the Cooper Test to measure your improvement:
- Run (or walk fast) on a flat surface for exactly 12 minutes
- Measure your distance in meters
- VO2max estimate: (distance − 504.9) ÷ 44.73
Run it at the start and the end. The delta will be motivating.
If running isn't your thing, use one of the calculator-based methods instead. But doing some form of consistent measurement is important — it keeps you honest about whether the training is working.
The Specificity Principle (Don't Train for Running and Expect Cycling Gains)
One practical note Galpin emphasizes: VO2max improvements are partly sport-specific.
If you train on a bike, you'll see bigger VO2max gains when tested on a bike. If you want to improve running performance, train by running.
This doesn't mean cross-training is useless — it's wonderful for recovery and overall fitness. But for targeted VO2max improvement, train on the modality you care about. Your muscles learn to extract oxygen from blood during the specific movement patterns they practice.
Combining with Strength Training
Galpin trains elite athletes who need both aerobic fitness and strength. His approach: cardio and strength training work together, not against each other — as long as you sequence them correctly.
Do strength work first. Do cardio after, or in a separate session. The reverse (cardio then lifting) leaves your muscles pre-fatigued for the strength work, reducing both performance and adaptation.
Zone 2 cardio is actually complementary to lifting — it improves recovery, metabolic health, and work capacity. High-intensity cardio (Zone 3–4) competes more directly with strength adaptations, so limit it to 1–2 sessions per week if you're also lifting seriously.
Where to Start
If the eight-week program sounds like a lot, that's okay. The 10-minute VO2max workout is a simpler entry point that uses the same core principles.
If you want to understand the science even more deeply, Galpin's Physiology of Endurance series covers everything from how your cells make energy to how elite athletes train at the cellular level. His Endurance Training Programming video is a complementary deep dive into periodization.
The guy knows his stuff. And he explains it clearly enough that you actually know what you're doing and why — which makes the training stick.