Alan Couzens

Alan Couzens

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Physiologist/coach; data-driven performance, HRV, and endurance modeling.

Race‑pace Simulation Reveals True Distance Readiness
SocialMar 13, 2026

Race‑pace Simulation Reveals True Distance Readiness

How to know you're "ready" for a specific distance: Complete a ~2/3 (Metric) simulation at race-pace as a regular training session with... - Minimal decoupling between pace/HR - No extended recovery needs beyond that of a regular loading day. For a marathon, I think...

By Alan Couzens
Early Season Surge: Pace Yourself Like an Ironman
SocialMar 12, 2026

Early Season Surge: Pace Yourself Like an Ironman

March is when athletes start blowing up their seasons. The sun comes out. 🌞 Motivation spikes. 🚀 Volume jumps up. 📈 But the season is a lot like an Ironman bike: These are just the opening miles. Be strong when it matters. Pace yourself.

By Alan Couzens
Marathons Unhealthy Only When Poorly Prepared or Mis‑paced
SocialMar 12, 2026

Marathons Unhealthy Only When Poorly Prepared or Mis‑paced

Two things that make marathons unhealthy IMO: 1. Inadequate preparation. 2. Inappropriate pacing (for your fitness). Both are very common, but that doesn't make running a marathon inherently unhealthy.

By Alan Couzens
Training Load Predicts VO2max, Aerobic Gains Ahead
SocialMar 11, 2026

Training Load Predicts VO2max, Aerobic Gains Ahead

A little #ProjectUnreasonable predictive modeling this morning - Training Load + Time In Zone vs predicted VO2max. Still a whole lot of pretty aerobic colors ahead for @JohnGoldman https://t.co/noj8ztob5u

By Alan Couzens
Heart‑rate Recovery Outperforms VO₂max for Metabolic Health
SocialMar 11, 2026

Heart‑rate Recovery Outperforms VO₂max for Metabolic Health

Everyone obsesses over VO₂max. But this paper found heart rate recovery to be more strongly tied with metabolic health metabolites than VO₂max. Peak capacity is nice. But how well you recover after a hard effort may tell us more about your metabolic health.

By Alan Couzens
Double Your Weekly Training to 12 Hours Total
SocialMar 11, 2026

Double Your Weekly Training to 12 Hours Total

This is very good advice. Especially the "you're prepared to train 6-8 hrs/wk" part. Personally, I would double it... 6hrs run + 6hrs cross-train But I am aware I have particular biases 😊

By Alan Couzens
Recovery, Not Stress, Drives Fitness Gains
SocialMar 10, 2026

Recovery, Not Stress, Drives Fitness Gains

This is common sense. You don't get healthier/fitter from the exercise stressor. You get healthier/fitter from the supercompensation effect of the body during *recovery*. No recovery. No fitness. You need both.

By Alan Couzens
Balancing Muscle Reserves and VO2max in Aging
SocialMar 9, 2026

Balancing Muscle Reserves and VO2max in Aging

In my view, the competing forces when it comes to health/longevity... 1/ Having sufficient reserves (both energy and muscle) so that you're not frail. 2/ Having very strong aerobic/metabolic fitness. These start to go against each other as you age. For example, for an...

By Alan Couzens
15% Body Fat: Optimal, Not Normal, Achieve via Deficit
SocialMar 9, 2026

15% Body Fat: Optimal, Not Normal, Achieve via Deficit

On 15% BF... A lot of talk on whether 15% BF (for men) is "normal" at the moment. Statistically... No, not normal. Yes, optimal. The 10-step process to getting there... Step 1/ A 250-500 kcal deficit each day. Steps 2 - 10/ See step 1. Things...

By Alan Couzens
Make Your Workouts Feel Like Cozy Slippers
SocialMar 9, 2026

Make Your Workouts Feel Like Cozy Slippers

Remember these? Your training routine should feel like a cozy pair of slippers. If it feels like this instead, you're heading for trouble. https://t.co/EBtKidZqog

By Alan Couzens
Hunter‑gatherers Produced Four‑to‑five Times More Poop
SocialMar 5, 2026

Hunter‑gatherers Produced Four‑to‑five Times More Poop

Did you know... That the daily 💩 weight of an average hunter-gatherer was ~4-5x the daily 💩 weight of a modern human? #FixYourFiber

By Alan Couzens