Alan Couzens

Alan Couzens

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

Build Zone 1 Reserve Before Hard Training
SocialApr 15, 2026

Build Zone 1 Reserve Before Hard Training

Zone 1 is an investment. It builds your fat-burning engine and expands your energy reserves. Zone 3/4 is a withdrawal. It spends from that reserve. Want your hard training to actually work? Build the reserve first. #Base

By Alan Couzens
Limited Time Means Prioritize Health Over Performance
SocialApr 14, 2026

Limited Time Means Prioritize Health Over Performance

No time → no high performance. That’s endurance sport. If time is limited, the goal shifts to health & fitness. Your training should shift too.

By Alan Couzens
Elite Athletes Blend Hard Sessions with Abundant Easy Miles
SocialApr 14, 2026

Elite Athletes Blend Hard Sessions with Abundant Easy Miles

You can argue threshold vs high-intensity all day. Both have produced world-class athletes. What hasn’t? Skipping the easy miles. Almost everyone at the top: *Something* hard + a lot of easy aerobic work That’s the recipe.

By Alan Couzens
Prioritize the Fitness Type You Need Most
SocialApr 12, 2026

Prioritize the Fitness Type You Need Most

Aerobic fitness & Metabolic fitness are two separate things. If you are a time-limited athlete, prioritize that precious time according to what you need the most.

By Alan Couzens
Aerobic System Dominates Events over 78.6 Seconds
SocialApr 12, 2026

Aerobic System Dominates Events over 78.6 Seconds

If your event lasts longer than 78.6 seconds, your Aerobic Energy system is the dominant contributor. #BuildThatBase

By Alan Couzens
Build a Solid Base Before VO2max Training
SocialApr 11, 2026

Build a Solid Base Before VO2max Training

Your regular reminder... You can only sharpen the base you've built. If you have no base, "VO2max work" is completely pointless.

By Alan Couzens
Tech Shows You Really Need Easy Training
SocialApr 10, 2026

Tech Shows You Really Need Easy Training

On tech… The real purpose of lactate meters, metabolic carts, HR monitors, etc? To tell you: “Yes… you really do need to train that easy.” Without it, most athletes never figure that out.

By Alan Couzens
Success Lies in Low‑Intensity, High‑Volume Work
SocialApr 9, 2026

Success Lies in Low‑Intensity, High‑Volume Work

Just had a lovely chat with a double Olympic gold medalist… ...and it left me with a very familiar conclusion: We all need more plain old low-intensity volume. If there’s a secret, it’s hiding in the boring stuff.

By Alan Couzens
Banister Model: Only Load and Timing Matter
SocialApr 9, 2026

Banister Model: Only Load and Timing Matter

Something I always find offers perspective... The Banister model is still a good model. It explains a large portion of athletic performance. It doesn't factor in all of the fancy stuff - whether you do 4 or 8 minute intervals, whether you...

By Alan Couzens
Youth Rushes; Age Teaches the Strength of Patience
SocialApr 8, 2026

Youth Rushes; Age Teaches the Strength of Patience

One of the cruel ironies of life: When we're young, & have all the time in the world, our impatience limits us. When we're older & our remaining time on this planet is limited, we discover the power of patience.

By Alan Couzens
Know Your Metabolic Profile, Not Just VO2max
SocialApr 8, 2026

Know Your Metabolic Profile, Not Just VO2max

The reason you should know your VO2max, ironically, has nothing to do with VO2max. It’s because you should know your metabolic profile: How much fat vs carbohydrate you burn at different intensities 🔥 And that requires a metabolic cart.

By Alan Couzens
Test Your Physiology, Train at the Right Intensity
SocialApr 7, 2026

Test Your Physiology, Train at the Right Intensity

Physiological testing isn’t about geeking out on numbers. It’s about *intensity discipline*... Knowing where you should be training & sticking to it! I spent years training at the wrong intensity. And it was my ultimate limiter.

By Alan Couzens
Prioritize Aerobic Training, Periodic Races Reveal True Fitness
SocialApr 5, 2026

Prioritize Aerobic Training, Periodic Races Reveal True Fitness

Yes, but... 1/ Going along with @hjluks most recent post... "Aerobic Deficiency Syndrome" is a freaking epidemic. That is, most of us have aerobic fitness orders of magnitude worse than our anaerobic fitness. This should be reflected in how much training time/emphasis...

By Alan Couzens
Time Your Fitness Boosters for Peak Performance
SocialApr 5, 2026

Time Your Fitness Boosters for Peak Performance

Fitness isn’t one engine. It’s a sequence of boosters - each one timed to fire at exactly the right moment 🚀 Get the sequence right → you peak on race day. Get it wrong → you never leave the ground. My latest: Building your season...

By Alan Couzens
High-Performing Athletes Suffer More Health Issues Than Elite
SocialApr 5, 2026

High-Performing Athletes Suffer More Health Issues Than Elite

Fascinating review on the relationship between level of training/performance and immune function. I would agree that "high" performing athletes generally have worse health than "elite" performing athletes. Because... 1/ They have less control over life stress (often global "Type A" personalities) 2/ They train...

By Alan Couzens
Release Unused Energy Through Simple Daily Movement
SocialApr 5, 2026

Release Unused Energy Through Simple Daily Movement

Energy you don’t use becomes a problem. Your body needs a release valve. You have one. Movement.

By Alan Couzens
Your Easy Runs Are Already Threshold Workouts
SocialApr 4, 2026

Your Easy Runs Are Already Threshold Workouts

"Coach, after reading Bakken's book, I think I need to add some threshold runs to my week" "Are you lactate testing your easy runs?" "No." "Good news: You're already doing them."

By Alan Couzens
Wearables Distinguish Real Fatigue From Cat‑like Laziness
SocialApr 3, 2026

Wearables Distinguish Real Fatigue From Cat‑like Laziness

Wearables (can) help with that eternal question... "I feel kinda tired today. Am I really tired, or am I just being a 🐱?" That question is a very stressful question for athletes. It can rattle around in your head for days. And...

By Alan Couzens
Walking and Running: One Continuum, Infinite Options
SocialApr 3, 2026

Walking and Running: One Continuum, Infinite Options

Walking & Running aren't separate activities. They lie on a continuum: 🚶‍♂️ 🏃‍♂️ You have all points on the range at your disposal... You can go... - All walking - A walk with 30s jog every 5 min. - A jog with walk breaks when...

By Alan Couzens
Consistent Low‑Intensity Training Drives Massive HR & HRV Gains
SocialApr 3, 2026

Consistent Low‑Intensity Training Drives Massive HR & HRV Gains

We all have such potential for fitness change if we simply stick with a simple, progressive, low-intensity training program for a long time. Most won't. They'll get bored. They'll get confused. They'll lose consistency. That's your advantage.

By Alan Couzens
Energy Deficit Undermines Training; Schedule Regular Anabolic Resets
SocialApr 2, 2026

Energy Deficit Undermines Training; Schedule Regular Anabolic Resets

When you train a lot, energy availability becomes the limiter. Not just chronically (RED-S)… but acutely. Day to day. Periods where you’re under-fueled = periods where your body is tearing down rather than building up. Over a season, these add up. That’s why you need...

By Alan Couzens
Endurance Success Depends on Monthly Training Load
SocialApr 1, 2026

Endurance Success Depends on Monthly Training Load

For serious endurance athletes, the key loading unit isn’t the training session... It’s the training *month*

By Alan Couzens
Plans Fail, Planning Wins: Athletes Need Structured Roadmaps
SocialApr 1, 2026

Plans Fail, Planning Wins: Athletes Need Structured Roadmaps

Most athletes don’t fail because they lack motivation. They fail because they lack a plan. If there's one thing experience has taught me... A season plan never gets completed 100% as written. But having one always gets you a lot closer than winging it! As...

By Alan Couzens
VO₂max Intervals Boost Running Economy, Not Max Capacity
SocialApr 1, 2026

VO₂max Intervals Boost Running Economy, Not Max Capacity

“VO₂max intervals” don’t really change VO₂max in sharpening. They change something far more useful: Economy - at all paces. Stop chasing effort. Start chasing efficiency.

By Alan Couzens
Mind Craves Complexity; Body Prefers Simple Routine
SocialApr 1, 2026

Mind Craves Complexity; Body Prefers Simple Routine

Your brain wants complex. Your body craves simple. Your brain wants variety. Your body thrives on routine.

By Alan Couzens
Just 10 Minutes of Brisk Walking Boosts Health
SocialMar 31, 2026

Just 10 Minutes of Brisk Walking Boosts Health

I'm still seeing a lot of people who don't understand what this paper is saying, so a quick summary... What this paper is not saying: The harder you train, the lower your risk of major disease/death. What this paper is saying: Adding a small...

By Alan Couzens
Run Slow, Build Mileage: Speed Limits Endurance
SocialMar 30, 2026

Run Slow, Build Mileage: Speed Limits Endurance

I wish I could claim originality here, but one of the greatest coaches of all time had similar thoughts many years ago.. "It is important to realize this point; that it is not the distance that will stop you in training as...

By Alan Couzens
Excessive Intensity Harms Performance; Choose a Balanced Approach
SocialMar 30, 2026

Excessive Intensity Harms Performance; Choose a Balanced Approach

"Why are you 'the intensity police'?" 👮‍♂️ Because I've seen (and experienced first-hand) the negative performance and health impact of too much intensity in your routine. I saw numerous swimmers get burned out & overtrained (some got very sick) purely from pushing...

By Alan Couzens
Fitness Demands Time: Accept It, Improve Faster
SocialMar 30, 2026

Fitness Demands Time: Accept It, Improve Faster

There’s a cost to everything. For fitness, the cost is time. The sooner you accept that, the sooner you actually improve.

By Alan Couzens
Boost VO2max by Increasing Weekly Mileage
SocialMar 30, 2026

Boost VO2max by Increasing Weekly Mileage

"So, coach, how do I get a really high VO2max?" Actually no one asks me that, but they do say things like... "Coach, how do I run a really fast 5K?" And, for all intents and purposes, they're the same question. My first &...

By Alan Couzens
Non‑GOFAI Best Serves as Rapid GOFAI Prototyping
SocialMar 29, 2026

Non‑GOFAI Best Serves as Rapid GOFAI Prototyping

It's becoming readily apparent that the best use of non-GOFAI is to build and quickly iterate on GOFAI.

By Alan Couzens
Coaches Must Tailor Strategies to Individual Athletes
SocialMar 29, 2026

Coaches Must Tailor Strategies to Individual Athletes

Athletes come in all shapes and forms. One athlete’s elixir is another athlete’s poison. The coach’s job? Know which is which. https://t.co/Qt4hMfDvJz

By Alan Couzens
We Need Real Endurance Coaches, Not Influencer Myths
SocialMar 29, 2026

We Need Real Endurance Coaches, Not Influencer Myths

This is why we need more endurance coaches (who know how VO2max is actually improved) and less "fitness influencers" around these parts 🤦‍♂️

By Alan Couzens
Strides: Keep Heart Rate Low, Prioritize Cadence
SocialMar 28, 2026

Strides: Keep Heart Rate Low, Prioritize Cadence

Strides, when done correctly, shouldn't be long enough (or fast enough) to significantly elevate your heart rate. Shoot for... - Set cadence first - Progressively lengthen stride over ~10-15s - Gradually build to ~5k pace or a little quicker - Once you hit that pace,...

By Alan Couzens
Six Months at 75% MHR Boosts Fitness and Speed
SocialMar 28, 2026

Six Months at 75% MHR Boosts Fitness and Speed

Related to another post from yesterday... Most athletes could afford to spend at least 6 months of every year capped at 75% MHR. You won't do that, because you'll get bored and distracted (probably by something you read here) But you'd be a...

By Alan Couzens
High‑intensity Training Belongs Later; Adaptations Differ in Timing
SocialMar 27, 2026

High‑intensity Training Belongs Later; Adaptations Differ in Timing

"Why don't we do high-intensity early in the build?" Because high-intensity and low-intensity adaptations operate over different timeframes... https://t.co/UUH1ANwGG7

By Alan Couzens
Cap Your Heart Rate at 70‑75% for Breakthrough Gains
SocialMar 27, 2026

Cap Your Heart Rate at 70‑75% for Breakthrough Gains

One of the simplest things you can do to set up a breakthrough season: Set a heart rate cap at AeT (~70-75%) & keep *every session* below it for the first few months of your build. Most watches will have a heart...

By Alan Couzens
Zone 2 Isn't Base Work—Treat It As High‑Intensity
SocialMar 26, 2026

Zone 2 Isn't Base Work—Treat It As High‑Intensity

In my opinion, Zone 2 is actually high-intensity training. Shouldn't be the majority of your base work. Use cautiously.

By Alan Couzens
Match Athlete Speed to Zones, Ditch Mileage Metrics
SocialMar 26, 2026

Match Athlete Speed to Zones, Ditch Mileage Metrics

If you know your athletes, and you know how fast they should be going in each zone, they are one and the same.

By Alan Couzens
Every Mile Counts: No Such Thing as Junk Miles
SocialMar 25, 2026

Every Mile Counts: No Such Thing as Junk Miles

When it comes to your base work, there's no such thing as "junk miles" There's just miles that you did and miles that you made excuses about.

By Alan Couzens
Elevated CAC: A Crucial Risk for Endurance Athletes
SocialMar 25, 2026

Elevated CAC: A Crucial Risk for Endurance Athletes

Fantastic thread on the ⬆️ CAC commonly found in endurance athletes. 🫀 IMHO, this is key 👇

By Alan Couzens
Coaches Can Finally Personalize Training Beyond Elite Athletes
SocialMar 24, 2026

Coaches Can Finally Personalize Training Beyond Elite Athletes

Like most coaches... Poorly. I had a squad template season plan that was based on what I had seen and what seemed to work for me. Then I would adjust it up or down depending on how tired the athletes looked...

By Alan Couzens
Health Isn’t Survival; Low‑carb Stress Is Unnecessary
SocialMar 24, 2026

Health Isn’t Survival; Low‑carb Stress Is Unnecessary

"Survival" & health are not the same either. Survival processes are unnecessarily stressful. I really don't get the extreme low carb thing. If you know your body is going to make glucose anyway (because it needs glucose to function), why not just...

By Alan Couzens
Data Reveals Individualized Sharpening Benefits for Athletes
SocialMar 24, 2026

Data Reveals Individualized Sharpening Benefits for Athletes

For example... Step into my brain, but please remove your shoes... How do I go about deciding when/if to begin sharpening an athlete prior to their A Race? I run a mixed effects model (comparing to population norms) to determine the relative performance...

By Alan Couzens
Master Timing, Not Just Load, for Peak Adaptation
SocialMar 23, 2026

Master Timing, Not Just Load, for Peak Adaptation

Two things drive adaptation: The load… and the timing of the load. Most athletes obsess over the first. The best athletes master the second.

By Alan Couzens
Avoid Sex and Leg‑draining Feats Before Competition
SocialMar 23, 2026

Avoid Sex and Leg‑draining Feats Before Competition

General conclusions: - Sex is not great as a pre-game warm-up (ideally finish 10hrs+ before) - Avoid any feats of prowess that make your legs go weak within 24 hours of competition. Other than that... https://t.co/e5olqnJMvd

By Alan Couzens
Stay Moderate: Avoid Excess, Keep Some Reserve
SocialMar 20, 2026

Stay Moderate: Avoid Excess, Keep Some Reserve

Big v Small for longevity. Small - Most serious problems are metabolic in nature. You'll avoid them by not spending too much time in an energy surplus, i.e. not being too big. But... If shit does go bad - you do have that...

By Alan Couzens
Endurance Athletes Reveal Divergent Physiological Engines
SocialMar 20, 2026

Endurance Athletes Reveal Divergent Physiological Engines

My latest post on the #MADcrew forum: Two athletes. Both training for endurance events. But with completely different engines. Here’s what the #PerformanceModeling data says about how @JohnGoldman and @inaki_delaparra actually work… https://t.co/oCTDk9EAjt

By Alan Couzens
Constant Load Boosts Predictability, Fuels Champion Performance
SocialMar 18, 2026

Constant Load Boosts Predictability, Fuels Champion Performance

Exactly. Everyone talks about tapering the load for performance. Few talk about tapering the load for stability. At a constant load, Fatigue plateaus much quicker than fitness (half-life of ~7 days) This means, if you hold the load constant, you don't just get faster...

By Alan Couzens