ONE CHAMPIONSHIP’S HYDRATION TEST

Putting a Stop to Manipulating the Scales

In the demanding world of combat sports, the fight is often won or lost long before the first punch is thrown. It’s a battle against the scales, also known as ‘weightcutting.’ Athletes do everything they can to make their weight limit. One of the methods used is dehydration. However, ONE Championship,known as a major Asian combat sports organization, has put a stop to this with a mandatory hydration program. This program goes beyond the traditional weigh-in and prioritizes the fighter’s health.

THE DANGER OF A DEHYDRATED BODY

To understand why the hydration test is important, we must look at what weight loss through dehydration does to the human body. When a fighter severely depletes their body of fluids, acute and potentially life-threatening risks arise. The brain, which is largely composed of water, literally shrinks a bit. This increases the space between the brain and the skull, significantly raising the risk of a concussion or more severe traumatic brain injury from a blow.

Additionally, severe dehydration can lead to reduced kidney function or even acute kidney failure, heart arrhythmias, and a drastic decrease in muscle strength and endurance. A fighter not only enters the ring physically weakened but also with impaired cognitive function, which slows down their reaction time and decision-making.

THE URINE  SPECIFIC GRAVITY TEST EXPLAINED

This is where the science behind ONE Championship’s hydration test comes in. Instead of just looking at weight, the organization measures an athlete’s hydration status via a urine specific gravity test. This test measures the concentration of dissolved particles in the urine compared to pure water. A low specific gravity (e.g., 1.010) indicates dilute urine, meaning the person is well-hydrated. A high specific gravity (e.g., 1.030) indicates concentrated urine, a clear sign of dehydration.

ONE Championship applies a strict limit: fighters must have a urine specific gravity of 1.025 or lower to pass the test. This value is internationally recognized as the upper limit for adequate hydration in athletes.

ATHLETES WHO RAN INTO TROUBLE

The most well-known case is that of former lightweight kickboxing champion Regian Eersel. Prior to his fight against Alexis Nicolas in April 2025, Eersel failed his hydration test three times. As a consequence, he was stripped of his world title before he even set foot in the ring. The fight did proceed, but only his opponent could win the now-vacant title. Eersel won the fight but lost his title (Bangkok Post, 2025).

At ONE Fight Night 11 in 2023, Muay Thai legend Superbon managed to pass the hydration test only on his third attempt. Dutchman Nieky Holzken was less fortunate and failed that evening, which cost him 30% of his purse for that fight (Atkin, 2023).

Other big names who have failed the hydration test in the past include Superlek, John Wayne Parr, and Nong-O, with various severe consequences as a result (Taylor & Taylor, 2022).

HOW TO ENSURE THIS DOESN’T HAPPEN TO YOU AS A ONE ATHLETE

1-4: As a ONE Championship athlete, passing the hydration test is crucial. This test measures urine specific gravity (USG) with a threshold of ≤ 1.025 to determine if you are well-hydrated. Below is a strategy I have put together for you as a dietitian.

2-4: Start hydrating days in advance. Drink water consistently—aim for about 2-3 liters per day—and ensure a good electrolyte balance with foods rich in sodium and potassium, such as bananas or caffeine-free sports drinks. On the test day itself, drinking about 500 ml (approx. 17 oz) of water a few hours before the measurement helps maintain your hydration level.

3-4: Avoid pitfalls like caffeine, alcohol, and diuretics in the days before the test, as these promote dehydration. It’s also better to avoid salty foods, as they cause fluid retention and can increase your USG value. Regarding weight management: opt for a gradual approach instead of last-minute dehydration, which is not only risky for your health but can also harm your performance.

4-4: Invest €30–40 in a simple digital refractometer or USG dipsticks. Test at home in the morning: if you repeatedly test ≤ 1.020, you have a 5-point margin compared to the ONE limit (1.025) to account for variations in lab collection. Record for three consecutive days to be sure. Legally, of course, only the official sample counts, but this way you eliminate surprises.

THE EXACT RULES THAT ONE ATHLETES MUST ADHERE TO CAN BE FOUND BELOW:
  • All athletes will participate in a combined hydration test and weigh-in 24 to 48 hours before the event.
  • Hydration will be checked through a urine specific gravity test in which every athlete will submit a urine sample under the supervision of a medical technician.
  • ONE’s doctor will test the athlete’s urine sample using a refractometer to ensure that the athlete is hydrated (hydrated = urine specific gravity ≤1.025).
  • The athlete’s weight must be within the contracted weight class or catchweight limit. If the athlete passes the hydration test, then he or she must weigh in immediately. If the athlete fails the hydration test, then he or she will not be allowed to weigh in until he or she has passed the hydration test.
  • If the athlete passes the hydration test and makes weight, then he or she is cleared to compete in his or her weight class.
  • If the athlete passes hydration but fails to make weight, then he or she may try again within the allotted 3-hour testing window. The athlete must pass hydration and make weight consecutively.
  • If the athlete fails to pass hydration or make weight during the allotted 3-hour testing window, then he or she will still be permitted to submit a hydrated sample outside of the testing window and weigh in to negotiate a catchweight bout.
  • A catchweight bout can be negotiated so long as both athletes are within 105 percent of each other’s official hydrated weight. The athlete who failed will surrender a percentage of his or her purse to the opponent

(Martial Arts – ONE Championship – The Home Of Martial Arts, z.d.)

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Roeg Kuijpers

Dietician, Strength & Conditioning coach, Personal Trainer