Hydration testing in MMA: where the rule came from

Two fighters can prepare for the same weight in the same month and meet completely different rules, because the sport answered the same problem twice and gave opposite answers. One answer removed the cut. The other kept it and put a fence around it.

What ONE built

The design removes the incentive rather than the practice.

• Walking weight, submitted and tracked. Athletes record their daily weight through camp, and the division is assigned from that data rather than from ambition.
• No late drops. Moving down a division inside the last weeks before an event is not permitted.
• Daily checks in fight week, rather than one number on one morning.
• A hydration test, by urine specific gravity, including one close to competition, with failure meaning removal from the card.
• No intravenous rehydration, which removes the tool that made large cuts survivable.
• Divisions renamed upward, so the same division name sits at a heavier limit than it does elsewhere. At the same body weight, a bantamweight in one promotion is a flyweight in this one.

The effect described by fighters who moved across is simple: the weight they walk around at in January is the weight they fight at in March. What the promotion gives up is the size advantage that a big cut buys, and that is the point.

What the commissions built instead

The American route accepts that fighters will cut and tries to keep the cut inside limits.

• Early weigh-ins, so the recovery window is as long as the format allows.
• Hydration checks and physician examinations before the fight is cleared.
• A second weight check on the day of the event, with a ceiling of about ten percent on what a fighter may put back on.
• Money. Missing weight costs 20 percent of the show purse and the win purse, with the win portion paid to the opponent.
• Division discipline. Fighters who miss repeatedly can be required to move up, and the plan asks matchmakers to place athletes in the lowest class they can safely make rather than the lowest they can reach.

This is regulation of the edges: the cut stays, the extremes get expensive, and the fighter who insists on a 20 percent cut meets a fine, a physician and a form.

The two designs compared

What neither of them fixes

Three things survive both designs.

1. The lower division is still an advantage. As long as a fighter believes he wins by being the bigger man in a lighter class, he will look for the edge that the rules still allow.
2. Monitoring depends on who does it. Daily weights submitted by the athlete are only as honest as the camp around him, and a hydration test can be passed by drinking rather than by not cutting.
3. Nobody has assigned the decision to stop. Both systems check numbers. Neither says who, inside the camp, is responsible for ending a cut that has gone wrong, which is the same gap wrestling has and the same one the corner has to fill.

What both designs did do is change what is normal. The practices that killed fighters in 1997 and in 2015 are now, in most places, either banned outright or expensive enough to argue about.

Common questions

What is a hydration test in MMA?

A urine specific gravity test. It measures how concentrated the urine is, which stands in for how dehydrated the athlete is. What the number means, and why the same threshold is used for opposite purposes in different sports, is in hydration testing: what 1.025 actually measures.

Why did ONE Championship ban weight cutting?

After the death of one of its fighters in December 2015 from complications of a weight cut, the promotion replaced the weigh-in with a system built around walking weight, daily checks and hydration testing.

Does the UFC test hydration?

The UFC runs under the commission of the jurisdiction it is in, so the answer depends on where the event is. The commission plan that spread from California includes hydration checks and a fight-day weight check.

Can you still cut weight in ONE Championship?

Not by dehydration, and that is the design. The division is assigned from walking weight, and hydration is checked repeatedly, including shortly before the bout. What that means for a fighter's camp is in Muay Thai weight classes, where the same promotion's rules apply.

Which system is safer?

Removing the cut removes the mechanism that has killed fighters. Regulating the cut leaves the mechanism in place and makes the extremes costly. The honest answer is that one system is safer and the other is easier to sell.