Why You Gas Out in Muay Thai (And How to Fix It)

Most fighters who gas out by round three are doing exactly the conditioning their coaches told them would fix it.

Your gas tank has three separate fuel pumps, and the one most fighters over-train is the one that actively caps the other two.

The circuits and HIIT that feel most like a fight are the ones killing your ability to explode again.

To understand what’s going wrong with your conditioning, although all three energy systems switch on together, treat each energy pump as separate: its own fuel source, its own plumbing, and its own way of bleeding out when you train it incorrectly.

Number one: the aerobic base. That’s your recovery reservoir. It is what recharges you between bursts, between rounds, between sessions. It’s also what allows you to relentlessly push the pace to drown your opponent in work rate.

Number two: the anaerobic alactic, or ATP-PC system. That’s your neuromuscular, explosive power, the raw snap in your strikes.

Number three: the anaerobic lactic, or glycolytic system. This is the pump most fighters default to when a coach says “do more conditioning.” It is also the pump that caps their engine when it’s overcooked.

The traditional Thai model correctly builds a legitimate aerobic base through all those 5-10k runs. It’s overdone, but the instinct is correct. A big aerobic reservoir is the foundation everything else sits on.

What the traditional model misses entirely is the ATP-PC system. The neuromuscular, strength, power, and speed side of the engine. That piece doesn’t get touched in traditional Thai training. And it’s the piece that delivers the raw, explosive efforts. The real fight demand is to explode, recover, and explode again. Those two adaptations, aerobic base and ATP-PC power, can coexist beautifully when you train them correctly.

The mistake is signing up for circuit training or CrossFit-style metcons and calling it conditioning. That approach blurs three distinct training stimuli into one sweaty mess. The aerobic system needs one fuel and duration. The alactic system needs another. The lactic system needs a third. Mix them up and you develop none of them well.

And the conditioning work they do add is almost always HIIT that defaults to the lactic system. It feels hard. A fight feels hard. So it’s assumed to be fight-specific.

But anaerobic lactic training actively blunts your aerobic development. It interferes with the very enzymes and mitochondrial adaptations that boost your recovery and sustain relentless output. Every round of lactic burn-out finishers you add, on top of what Muay Thai already gives you, might actually be capping your engine.

Muay Thai training already builds sport-specific conditioning. Bag work rounds, pad rounds, sparring rounds: these all contribute threshold training and some lactic power. You don’t need your supplemental S&C to give you more of the same. You need it to plug the gaps.

So what are the gaps? Aerobic capacity and aerobic power, done in a structured way that doesn’t interfere with your skill work. And ATP-PC power: explosive, short-duration, fully-recovered efforts that develop the neuromuscular qualities the traditional model never touches.

Lorenzo, an Italian heavyweight, is the kind of KO artist whose opponents get starched when he lands. But in our first call, he told me something that should get the attention of every fighter who has ever blamed their gas tank on genetics.

He said: “From my first fight until now, the problem is always stamina. Even when I win, I know I could have hit more. I can see the openings. I can see where to land. If I throw ten punches with this engine, I could throw twenty with a bigger one.”

He fought for the Italian title. “I lost because in the fourth round I was gone. I’m not fighting anymore. I’m surviving. My opponent sees me. He knows I’m surviving. I won the first three rounds. I was hitting him, I was in control. Then the fourth round comes and my body quits. If my engine was there, I knock him out. And this opponent — he went to the world championship and lost a split decision. Against me, he lost three rounds of four. He is a very strong fighter. And I dominated him.”

That’s the reality of the KO artist who can’t last. He dominated a world title contender for three rounds, and then his engine gave out.

Lorenzo had been working with a personal trainer. A good strength and conditioning coach, he told me. But then he added this… “He’s a CrossFit trainer. He trains combat athletes too. But he’s not a fighter. He’s never stepped in the ring. I think this matters if you want to make the next level.”

Lorenzo had been in the exact trap I’m describing. A trainer who understood fitness but didn’t understand fight physiology, and blurred the energy systems into one bucket and called it conditioning.

We ran Lorenzo through the performance testing. His strength was solid, his explosive power excellent — standing broad jump and sprint speed both at a high pro level. But his aerobic power came back at three out of ten on the Cooper run, which put him in the bottom two percent of pro fighters.

He looked at his profile and he wasn’t surprised. He said, “Before the test, I already knew. I’m good in the power. I’m good in the explosive. And I knew my cardio had to improve. I understand.”

So we got to work. Starting with fourteen weeks of zero lactic conditioning. None at all.

Instead, his supplemental sessions were things like 40 minutes of Zone 2 running or shadow boxing at a pace where he could still hold a conversation. That’s cardiac output training. It feels insultingly easy, like you’re wasting your time. But the changes to your heart muscle don’t care about your perceived effort.

On other days, he did things like 12 reps of 6-second hill sprints with 60-90 seconds recovery between each. That’s high resistance intervals. Maximum effort for six seconds, then rest until his heart rate dropped back down. It’s ATP-PC work: improving the endurance capacity of fast twitch muscle fibers without touching the lactic system at all.

Lorenzo trusted the process. In that first call, after I explained that the early training would feel easy, he said: “I know it looks easy. But it’s good. I will do it well. Don’t worry. I will do it very well.”

One full training cycle later, he came out the other side still explosive, still the KO artist, but now with the energy to deliver it every round of the fight. The aerobic base had caught up to the power.

Since then, Lorenzo has won the ITMAO -91kg International belt and successfully defended it. The same fighter who couldn’t survive a fourth round is now a champion who can go the distance and still find the finish.

We didn’t guess with Lorenzo. We tested. The standing broad jump that confirmed his explosive power was already pro level, the Cooper run that exposed his 3-out-of-10 aerobic base: those numbers identified the constraint and told us exactly what not to train.

You can run the same two tests yourself inside 30 minutes, including a warm-up. But the order matters.

First, the standing broad jump. Test this before anything else, while you are fresh. Explosive power testing demands an unfatigued nervous system. Do the jump after the run and the number is out.

Stand behind a line, feet shoulder-width apart. Jump forward as far as you can from a standing start. No run-up, no step into it, no falling backwards. Measure from the line to behind your heels when you land. And take your best of three attempts.

Now divide that distance by your height. Use the same units for both: metres divided by metres, or inches divided by inches.

Male pro fighters should aim for a ratio of 1.42 or higher. And female pro fighters should aim for at least 1.36.

If your ratio falls below that threshold, you are not generating enough explosive power for your frame. That is the ATP-PC system calling for attention, and no amount of roadwork will fix it.

Second, the 12-minute run.

Once the jump is done, find a track, a flat stretch of road, or a treadmill. Warm up and then run as far as you can in 12 minutes. Pace yourself: the test measures sustained output, not a sprint.

Here are the minimum pro-level thresholds.

Male fighters under 91 kg: at least 2,640 metres, or 1.64 miles.

Male fighters 91 kg and over: at least 2,360 metres, or 1.48 miles.

And female fighters: at least 2,290 metres, or 1.42 miles.

Those are the minimum. More distance is always better. If you are still building your base, use these as targets to work toward.

While you are at it, check your resting heart rate. Take it first thing in the morning, before you get out of bed. If it is above 60 beats per minute, your aerobic system is not as efficient as it needs to be for the repeated explosive demands of a fight.

Miss either of those markers, the run distance or the resting heart rate, and your aerobic system is the bottleneck. Your recovery between bursts, between rounds, between sessions will always cap your output, no matter how much work you pour into the other two pumps.

These two numbers, your jump-to-height ratio and your 12-minute distance, draw a clean line through your engine. One tells you if your explosive power is sharp enough. The other tells you if your recovery tank is big enough. Most fighters are deficient in one, not both. The art is training the gap without blunting what is already working.

That is exactly what we did with Lorenzo. And that is what the framework in the next section is built to do.

This is the 14-week framework that turned a 3-out-of-10 aerobic base into a two-title champion.

For the first 10 weeks of a training cycle, my fighters do no lactic conditioning. Instead, their supplemental sessions target two zones: aerobic and ATP-PC.

A cardiac output session might be 30 to 60 minutes of shadow boxing and skipping circuits, or light running. The intensity rule is simple: you can hold a conversation the whole time. That’s it. Zone 2, a four or five out of ten on the effort scale.

A high resistance interval session might be 8 to 12 reps of 6-second hill sprints, with 60 to 90 seconds of recovery between each. Standing still until your heart rate drops to 130-140 bpm. The work is maximal but the duration is so short you never tip into the lactic zone.

The lactic work doesn’t show up until the final four-week block of the cycle. And then it’s just one session per week. I use something called cardiac power intervals: 60 to 180 seconds at max intensity, targeting maximum heart rate, with plenty of recovery between efforts. That’s four total sessions across a 14-week block. It’s the minimum effective dose, enough lactic exposure to sharpen the system without interfering with the aerobic and alactic work we’ve built under the hood.

Across a full 14-week training cycle, that works out to about five to eight percent of total supplemental sessions touching the lactic system. The other 92 to 95 percent is aerobic and alactic.

And this applies whether you’re an amateur training around a day job or a pro on a full-time schedule. The variables are how many sessions you can fit in a week, not the principle. A fighter training three supplemental sessions per week follows the same split as a fighter doing five. The ratio holds.

Every fighter’s instinct says easy running makes you slow. If the work doesn’t feel hard, it’s not building anything. But steady cardiac output training increases your heart’s left ventricle size.

A bigger chamber means more blood per beat, and more oxygen delivered to working muscle at every intensity. Your explosive work recovers faster because of it.

The metric that proves it is heart rate recovery. How quickly does your heart rate drop between rounds? A bigger pump clears the waste faster. That’s the engine you’re building with the easy work. It’s a different kind of conditioning, it builds your foundation.

Hard work feels hard. But that does not mean it is building what you think it is.

Lorenzo started with a novice-level aerobic base and pro-class power. He was a KO artist who couldn’t last three rounds. One cycle of targeted work, plugging the gaps instead of duplicating what Muay Thai already gave him, and his engine caught up to his power.

Most fighters gassing out in round three are in the same position Lorenzo was and don’t know it. Test to reveal your gap, then do the training that closes the gap. Everything else is guessing.

The Scorecard maps your current training and results against success benchmarks, then gives you tailored resources to close whatever gaps it finds. Link below.
Once you’ve found your gaps, the next video shows how to stack conditioning and coordinated strength training across a full cycle, from aerobic capacity through to lactic power, so nothing cancels out. Watch it next.