Round seven was new territory: what happens when the engine runs out

On 29 August 2026 at the O2 in London, Moses Itauma won every round against Filip Hrgović and lost the fight. He put Hrgović down in the second. He was ahead on every card. In the ninth his corner threw the towel because he was swaying on his feet and could no longer keep his hands up.

One fact from that night explains more than any amount of round-by-round analysis, and it is a matter of record rather than opinion.

I know nothing about how that fighter prepared, and I am not going to speculate about it. What I can do is explain what happens physiologically to any athlete in that situation, because it is not mysterious and it is not a character flaw.

The heavier man tired first

Itauma weighed 241.7 lb at the weigh-in. Hrgović weighed 236.2.

Five and a half pounds. The bigger man, the younger man, the faster man, and the one who ran out.

The assumption in most gyms is that size and power belong to the same conversation as durability. They do not, and carrying additional mass through 36 minutes costs energy in every one of them.

What gassing out actually is

Start with what the research says about the demands, because the numbers are higher than most people expect.

In amateur boxing, measured heart rates during competition sit around 190 to 200 beats per minute. Blood lactate after three 3-minute rounds runs between roughly 9 and 14 mmol per litre depending on the study.

Fractional utilisation of maximum oxygen uptake during simulated rounds has been measured between 85 and 100 percent.

That is 9 minutes of work. Professional championship boxing is 36.

Now the finding that surprises people. Despite all that lactate, researchers examining the metabolic profile of boxing describe it as predominantly aerobic.

The punches are anaerobic. The fight is not. The engine that has to be there for 36 minutes is the aerobic one, and it is the one that gets least attention in a gym where everybody is working on power.

The number that describes a fighter running out

There is a measurement in the boxing literature that says everything about this, and almost nobody outside sports science has seen it.

It is the work-to-rest ratio: how much of the round is spent actually working, against how much is spent recovering.

The figures below come from Slimani and colleagues, reviewing performance and physiological responses in amateur boxing competition.

Read the top row as a picture rather than a statistic. It is a fighter progressively ceasing to work. Not choosing to conserve, not being outboxed.

The engine reducing its own output because it cannot sustain what it was doing.

The elite boxer holds his ratio. That is the entire difference, and it stays invisible until somebody makes him hold it for longer than he ever has.

Why lactate is not the villain

The gym explanation is that you fill up with lactic acid and seize. That model is out of date, and it matters, because it points training in the wrong direction.

Lactate is a fuel, whatever its reputation as waste. The body shuttles it, transports it and burns it, and a well-trained athlete does this remarkably fast.

So the difference between two fighters is not that one produces lactate and the other does not. Both produce it, in similar quantities, doing similar work.

The difference is the balance between production and clearance.

One fighter clears and re-uses it at roughly the rate he makes it. His concentration rises, then holds. The minute between rounds is enough to bring it down, and he arrives at the next round close to where he started.

The other produces faster than he clears. Round one leaves a residue. Round two starts from that residue and adds to it. By round six he is carrying the accumulated cost of every round before it, and the minute between rounds is no longer a recovery, only a pause.

This is why fighters hold, and hold, and then go all at once, instead of fading gradually, which is what an audience sees and calls a lack of heart.

Why a record of early stoppages hides this

The trap applies to a great many young fighters nowhere near a world title.

If every fight ends inside 3 rounds, nothing about the aerobic engine is ever tested. Not in the fight, and often not in the camp either, because camp gets built around what the fights have demanded so far.

A fighter can spend years accumulating evidence that he is devastating, and none of that evidence tells him what happens in round nine. The record looks like proof of dominance.

It is also an absence of information, and from outside the two are indistinguishable.

The first time the question gets asked is the first time it can be answered wrongly.

What a camp does about it

The training side belongs to a strength and conditioning coach, not to me. What belongs to me is the fuel, and three things decide whether an engine can express what it has.

Glycogen. Repeated high-intensity work runs on stored carbohydrate. A fighter arriving at the ring with depleted muscle glycogen has a ceiling on his round-nine performance that no amount of conditioning overcomes. And the way most fighters arrive at fight night is through a weight cut that empties exactly that store.

The refuelling window after the scale is the single largest nutritional lever on late-round capacity.

The size of the cut. Every kilogram taken off aggressively in the final week is paid for in the second half of the fight. A fighter who cuts less arrives with more, and the decision governing that is made months earlier, when the weight class is chosen.

Fuelling the work that builds it. The sessions that develop the aerobic engine are long and repeated, and they cannot be done properly on a chronic deficit. A fighter in a permanent cut trains the engine at half capacity for the whole camp, then wonders why it is not there on the night.

None of that substitutes for the conditioning work. It is the difference between having an engine and being able to use it.

What this is not

I am not diagnosing anybody's preparation. I have no knowledge of what happened in that camp, and neither does anybody else writing about it this week.

What that fight did was ask a question a career of early finishes had never asked. A 21-year-old met the part of the sport that cannot be skipped, in public, against a man who had been in deep water repeatedly and knew what was on the other side of it, and there is nothing scandalous or shameful in that.

The useful lesson is for everybody watching who is nowhere near that level. If your fights have all ended early, you do not know what you have.

You only know what you have not needed yet.