Hydration Testing at Weigh-Ins: What It Catches

Every serious attempt to regulate weight cutting in combat sports eventually arrives at the same instrument: a refractometer, a urine sample, and a number with three decimal places. Urine specific gravity is the test the NCAA uses to gate wrestling certification, the test the NFHS mandates for high schools, and the test at least one major MMA promotion built an entire fight-week protocol around.

It is also a test whose own users publish its error rate, whose validity in exactly this population has been described in the peer-reviewed literature as "quite problematic", and which is biased in a specific direction against the exact body type combat sports select for.

None of that makes it useless. It makes it a gate rather than a verdict, and confusing the two is how a reasonable safety measure turns into a false reassurance. This article is what the thresholds are, where they came from, what they demonstrably catch, and the three things they do not.

1.020

NCAA wrestling threshold. Above it, no body-composition test; the athlete returns no earlier than 24 hours later

NCAA 2025-26 Men's Wrestling Weight Management Packet

80% / 31%

At the 1.020 cut-off, the proportion of dehydrated and of hydrated wrestlers correctly classified against a blood criterion in the NCAA's own validation

NCAA packet, Supplement No. 8

~90%

Prevalence of hypohydration reported by urine specific gravity in combat-sport athletes, often despite stable body mass

Zubac et al., Eur J Sport Sci 2018;18(7):920–929

~14%

Plasma volume reduction measured after a two-hour hot-bath weight-cut protocol — with every blood marker back to baseline by the weigh-in 24–26 hours later

Connor et al., Eur J Appl Physiol 2022;122(10):2243–2257

What this comes down to

Urine specific gravity measures the concentration of solutes in urine, which correlates with hydration status but is not a measurement of it. Everything below follows from that distinction.
Two thresholds are in common use and they are not interchangeable: 1.020 in NCAA wrestling, 1.025 under NFHS rule 1-5-1 and in the fight-week protocol ONE Championship has publicly described.
The NCAA is the only body that publishes its validation, and the numbers are candid: at 1.020, about 80% of dehydrated wrestlers and about 31% of hydrated ones were correctly classified against blood fluid volume in a 50-wrestler sample.
Peer-reviewed work reports hypohydration prevalence near 90% in combat-sport athletes by this test, often alongside stable body mass — a pattern that suggests the threshold, not the athletes, is what needs interpretation.
Fat-free mass is positively associated with specific gravity. A 2024 quantitative review found ρ = 0.38 overall, meaning muscular athletes are more likely to read as hypohydrated when they are not.
The most important limitation is temporal. In a controlled study, blood markers disturbed by a large acute cut had returned to baseline by the weigh-in roughly 24–26 hours later. A test at the scale can be clean after a cut that was not.
A hydration test used as a gate before an irreversible decision is defensible with a known false-failure rate. The same test used as a verdict on whether a cut was acceptable is not.

What the test actually measures

Specific gravity is the density of a fluid relative to water. Urine specific gravity therefore measures how concentrated the urine is — how much dissolved material the kidneys have packed into a given volume.

The physiological logic is sound at the level of direction. As a person dehydrates, the kidneys conserve water and the urine becomes more concentrated, so specific gravity rises. The NCAA's own documentation puts it plainly: "Physiologically, urine specific gravity has a wide range, but studies have shown that as a person dehydrates the urine specific gravity increases."

Note what that sentence does and does not claim. It establishes a relationship, not an equivalence. Urine concentration is downstream of many things: how much you drank in the last hour, when you last ate, protein intake, muscle metabolites such as creatinine and urea, recent exercise, and how recently you last urinated. Any of those can move the number without a corresponding change in whole-body fluid status.

The instrument matters too. A refractometer measures refractive index and is the reference method in every programme that specifies one. A urinometer floats a calibrated bulb. Reagent test strips estimate the value colorimetrically, and the NCAA states flatly that "Test strips are not permissible as a measuring device for specific gravity" — a rare case of a governing body legislating the class of instrument as well as the threshold.

Two thresholds, and why they differ

The two numbers in circulation are 1.020 and 1.025, and they belong to different programmes with different jobs.

1.020 — NCAA wrestling. The purpose here is measurement integrity before an irreversible decision. A dehydrated athlete's body composition reads leaner than it is, which would certify a legal minimum weight lower than their true floor and bake the dehydration into the whole season. The packet's rule: "If specific gravity is greater than 1.020, the wrestler must return not earlier than 24 hours in a hydrated state for a retest."

1.025 — NFHS rule 1-5-1, which requires every state association to run a weight-management programme including "a specific gravity not to exceed 1.025", a minimum body-fat floor and a weekly weight-loss cap of 1.5 percent. Same purpose, looser threshold, administered by state associations rather than a single national office.

1.025 in professional MMA. ONE Championship's fight-week programme, which the promotion introduced in 2016 and has described publicly since, uses a urine specific gravity check with a refractometer under supervision, with 1.025 or below counted as hydrated. Published descriptions of the protocol report checks on the day after arrival and again in the hours before the event, with failure meaning removal from the card.

We treat that third case with more caution than the first two, and say so: the operative primary document for the promotion's current rules was not reachable during research for this article, so the ONE protocol is described here as it has been publicly reported rather than quoted from the rulebook. Treat the detail as indicative and confirm it with the promotion if it matters to you.

A tighter threshold is a stricter test in the sense of catching more dehydrated athletes. It is also a test that fails more people who are fine, and the trade-off between those two is not a technicality. It is the entire design question.

The one regulator that showed its working

The NCAA packet contains a supplement titled "Why The Urine Specific Gravity Cut-Off Point Is Where It Is". It is the most honest paragraph any combat-sport governing body has published about a threshold, and it starts by conceding the point:

Why set the urine specific gravity test at 1.020? Why set the weight class at 141 or 184 or score 2 points for a takedown? As with many rules in wrestling and other sports too, the decisions are based in part on good evidence, but they are somewhat arbitrary, too.

Then it describes the study. Urine specific gravity samples were taken from 50 wrestlers alongside blood samples measuring fluid volume — the packet describes blood fluid volume as "a very good indicator of the body's hydration status", with clear cut-off points for a state of dehydration. Three candidate thresholds were compared against that criterion:

Threshold	Dehydrated correctly identified	Hydrated correctly identified
1.015	89%	13%
1.020	80%	31%
1.023	60%	38%

Read the right-hand column. At the chosen threshold of 1.020, roughly two in three properly hydrated wrestlers were classified as dehydrated. That is not a small error rate hiding in a footnote. It is the headline result, published by the organisation that uses the test.

The packet then explains the asymmetry that makes the choice defensible anyway:

Conversely, a hydrated wrestler who fails the test (that is, appears dehydrated) will have to test a second time, which is inconvenient. However, there are no health or performance risks associated with coming back a second time. So, it is more important to catch dehydrated wrestlers than to miss hydrated wrestlers.

That is correct reasoning under uncertainty, and it works because of what the test is being used for. When the cost of a false failure is a wasted afternoon and the cost of a false pass is a season built on a dehydrated measurement, you accept the false failures. Change the consequence — make a failure mean a cancelled fight and a lost purse — and the same error rate is a very different proposition.

The 90% problem

The most uncomfortable finding in this literature comes from combat sports specifically.

Zubac and colleagues examined urine specific gravity as an indicator of dehydration in Olympic combat-sport athletes, and reported that recent investigations find a universally high prevalence of hypohydration, around 90%, measured by USG in these athletes — often in spite of stable body mass.

That combination is the problem in one sentence. If nine athletes in ten test as dehydrated while their body mass is not moving, either the entire population is chronically dehydrated in a way that does not show up on a scale, or the test is reading something other than whole-body fluid deficit in this population.

The paper's own assessment of the situation is quotably blunt about the state of the evidence: the use of laboratory-derived benchmarks in applied settings, inconsistent sampling methodology, incomplete understanding of how confounders affect end-point readings, and the poorly understood potential for renal adaptation to habitual dehydration in combat athletes together make hydration assessment by USG "quite problematic", particularly where diet and training are not controlled.

That last confounder deserves emphasis because it is specific to this sport. Combat athletes are, by definition, a population that repeatedly and deliberately dehydrates. Whether kidneys adapt to that pattern in a way that shifts baseline urine concentration is exactly the kind of question the field has not settled, and it is the question that would determine whether a threshold derived from general populations means anything here.

The muscle bias

There is a second systematic problem, and it has been quantified.

A 2024 quantitative review in Translational Sports Medicine pooled specific gravity estimates from athletes and active adults — 171 estimates from men and 59 from women — and tested whether fat-free mass is associated with USG. It is: ρ = 0.36 in men, ρ = 0.57 in women, ρ = 0.38 combined, all statistically significant.

The authors' conclusion is direct: athletes with larger amounts of fat-free mass are more likely to have elevated USG, and if the test continues to be used in sport settings, research is needed to determine whether fat-free-mass specific thresholds would be more appropriate.

The mechanism is not mysterious. Muscle metabolism produces creatinine, urea and uric acid, all of which are solutes, and all of which raise the density of the urine that carries them. A larger amount of contractile tissue produces more of them at rest.

Combat sports select hard for exactly this body type: lean, muscular, and light for their fat-free mass. Applying a fixed threshold derived from mixed populations to a population chosen for its muscularity produces false failures systematically rather than randomly — and the leaner and more muscular the athlete, the more likely they are to be told they are dehydrated when they are not.

This is not an argument against testing. It is an argument for reading a marginal result as a marginal result.

What the test cannot see: the markers come back

Here is the limitation that matters most for professional combat sports, and it comes from a controlled study of exactly the practice the testing exists to prevent.

Connor and colleagues put thirteen experienced male MMA athletes through a rapid weight-loss protocol including two-hour hot-water immersion sessions, in a crossover design comparing fresh water with roughly 5% Epsom salt water. Total body mass lost across the process was about 5.3%. Immediately after the two-hour bath protocol, blood urea nitrogen, creatinine, sodium, chloride, haemoglobin and haematocrit were all elevated, and plasma volume had fallen by approximately 14%.

Then this, from the same study: all of those markers had returned to baseline values by the following day's weigh-in, roughly 24 to 26 hours after the protocol, following a structured rehydration of 150% of mass lost over six hours plus 6–8 g/kg of carbohydrate.

Sit with what that implies for a test at the scale. In a day-before-weigh-in format, an athlete who has executed a large acute cut and then rehydrated with a competent protocol can present at the weigh-in with normalised blood chemistry. A urine test at that moment is measuring the recovery, not the cut.

The testing regimes that acknowledge this are the ones that test repeatedly across fight week rather than once at the scale — which is precisely what the ONE Championship protocol as publicly described attempts, and precisely what makes it a more ambitious design than a single check. A single test at the weigh-in of a day-before format is asking a question at the one moment it is least likely to be answered.

The same finding cuts the other way too, and honesty requires saying so: in that study, no index of performance tested — countermovement jump, grip strength, isometric mid-thigh pull, or a three-minute all-out cycle test — was impaired at the point of competition, and the athletes were slightly above baseline mass by the weigh-in. The authors' conclusion was that under those conditions, with more than 24 hours of supervised recovery, performance was not impacted. That is a study of thirteen athletes with a research team managing the rehydration, and it is not a licence. But it does mean the honest summary of the evidence is not "the test catches damage that would otherwise show" — it is "the test is looking at a moment when a great deal has already been undone."

The confounders, in the order they will bite you

The literature lists the things that move a specific gravity reading independently of whole-body fluid status. Ranked by how likely each is to affect an athlete at a real weigh-in:

Time since the last urination. The first sample of the morning is the most concentrated of the day in almost everyone, because it represents overnight production without intake. A programme that tests first thing and a programme that tests mid-afternoon are not asking the same question, and neither typically says which it is doing.

Recent fluid intake. Drinking shortly before a sample dilutes it before body water has meaningfully changed. This is the confounder that makes a same-hour retest close to meaningless, and it is why the NCAA imposes a 24-hour minimum wait after a failure rather than letting an athlete drink and return.

Protein intake and muscle metabolites. Creatinine, urea and uric acid are solutes. High protein intake and high muscle mass both raise the load the kidneys are excreting, and both are near-universal in this population.

Recent intense exercise. Training shifts fluid compartments and alters renal handling, so a sample taken after a session is measuring something other than a resting state.

And food generally. Recent ingestion is on the list of confounding activities in the published assessments, alongside urination and defecation, for the straightforward reason that all of them change what is in the bladder.

None of these are exotic. Every one of them describes something a fighter routinely does during fight week, which is a compact way of saying that the conditions under which the test performs best are not the conditions under which it is used.

Gate versus verdict

Everything above resolves into one distinction, and it is worth stating as cleanly as possible.

Which test happens where, and when, is a separate question from what the test does — the room itself is described in how a wrestling weigh-in works.

A hydration test is being used as a gate when a failure delays an irreversible decision. NCAA certification is the model case: fail, come back in 24 hours, and nothing is lost but time. The false-failure rate is tolerable precisely because failing costs an afternoon. The test does not have to be accurate about any individual; it has to be accurate enough about the population to keep dehydrated measurements out of the system.

A hydration test is being used as a verdict when a failure ends the competition. That is a far heavier load for an instrument with a two-in-three false-failure rate at the chosen threshold in the population it was validated in, and a documented systematic bias against muscular athletes. It can still be the right policy — a promotion may reasonably decide that removing dehydrated athletes from a card is worth removing some hydrated ones too — but it should be adopted with the error rate stated, not with the implication that the number is a diagnosis.

The failure mode to avoid, in either direction, is treating a pass as evidence that a cut was acceptable. It is not. It is evidence that at one moment, one marker of urine concentration was below a threshold that its own publishers describe as somewhat arbitrary.

What a fighter should actually do with this

Practical consequences, in order of usefulness.

Know which threshold applies to you and which instrument will be used. 1.020 and 1.025 are meaningfully different, and a refractometer and a reagent strip are meaningfully different instruments. In a programme that specifies a refractometer, ask for one.

Treat a marginal reading as marginal. If you are lean, muscular and reading 1.021 with stable body mass, the literature says that is a common result in athletes like you and does not by itself establish a fluid deficit. It also does not establish that you are fine. It establishes that the test has not resolved the question.

Do not plan around passing it. The most dangerous use of a hydration test is as a target — arranging fluid intake in the hours before to produce a compliant sample. That optimises the number rather than the state the number is supposed to represent, and the confounder list above is exactly the manual for how to do it. It is also the reason water loading before a weigh-in is a more complicated subject than it is usually presented as.

Use body mass as your own instrument. Daily weight in consistent conditions, taken across weeks, tells you far more about your own fluid and energy balance than a single urine sample tells anyone. It is also the measurement that turns a fight-week emergency into a problem you saw in week three, which is most of what fight camp planning is for.

And keep the medical question with a medical professional. No published figure establishes what is acceptable to attempt unsupervised, at any specific gravity. The absence is information.

What would be better, and why nobody uses it

The honest answer to "is there a better test" is yes, several, and none of them is deployable at a weigh-in.

Plasma or serum osmolality is generally regarded as a stronger reference standard, and the NCAA's own validation used blood fluid volume as its criterion for exactly that reason. It requires a blood draw, a laboratory and a turnaround, none of which exist in a hotel ballroom ninety minutes before a card.

Urine osmolality is better than specific gravity but needs an osmometer. Bioimpedance is fast and portable and its agreement with reference methods in acutely dehydrated athletes is not good enough to build a rule on. Isotope dilution is the reference method for total body water and takes hours.

Which leaves specific gravity: cheap, immediate, non-invasive, and imperfect in ways its users have documented. The NCAA supplement's closing lines acknowledge exactly this, asking whether the cut-off could be changed, whether more data are needed, and whether a better test should be sought — and answering yes to all three.

That is the correct posture toward this instrument, and it is available in writing from the organisation with the most experience of using it. Anyone presenting a specific gravity reading as a definitive statement about a fighter's hydration has more confidence in the test than the people who validated it.

What we could not verify

ONE Championship's current rules text. The promotion's own rules page was not reachable during research. The protocol is described here as publicly reported — refractometer testing, a 1.025 threshold, repeated checks across fight week, removal from the card on failure — and not quoted from a primary document. Confirm with the promotion.
The full Zubac et al. text. We worked from the published abstract and indexed summary of the European Journal of Sport Science paper; the full text sits behind a paywall. The ~90% prevalence figure and the "quite problematic" assessment are the paper's own framing, but we have not read its complete methods.
The provenance of the 1.025 threshold. The NCAA published its derivation for 1.020. We did not locate an equivalent published validation for 1.025 in either the NFHS programme or professional use, and we do not know whether one exists.
Whether renal adaptation to repeated dehydration shifts baseline USG in combat athletes. This is raised as an open question in the literature. It is not settled, and it would materially change how any threshold should be interpreted in this population.
Nothing here is specific to you. Not your body composition, your training load, your diet, your medical history, or the programme testing you.

Questions fighters ask

What is urine specific gravity and what does it measure?

Urine specific gravity measures the density of urine relative to water, which reflects how concentrated it is — how much dissolved material the kidneys have packed into a given volume. As a person dehydrates, the kidneys conserve water and the urine becomes more concentrated, so the value rises. It is a correlate of hydration status rather than a measurement of it: recent fluid intake, food, protein and muscle metabolites, exercise and time since last urination all move the reading. That is why it is best understood as a screening instrument rather than a diagnosis.

What USG do fighters need to pass a hydration test?

It depends entirely on the programme. NCAA wrestling requires 1.020 or lower, and an athlete above that must return no earlier than 24 hours later for a retest. NFHS rule 1-5-1 requires state high-school programmes to use a specific gravity not exceeding 1.025. In professional MMA, ONE Championship's publicly described fight-week protocol uses 1.025 or below as its hydrated threshold, checked with a refractometer under supervision. Confirm the figure with the organisation testing you, because the two thresholds are not interchangeable and the consequences of failing differ enormously.

How accurate is urine specific gravity as a hydration test?

Moderately, and the NCAA publishes the trade-off. Its validation compared three thresholds against blood fluid volume in 50 wrestlers: at 1.015, 89% of dehydrated wrestlers but only 13% of hydrated ones were correctly classified; at 1.020, 80% and 31%; at 1.023, 60% and 38%. So at the threshold in use, roughly two in three adequately hydrated wrestlers are classified as dehydrated. The programme selected 1.020 on the explicit reasoning that catching dehydrated athletes matters more than avoiding false failures, given that a false failure costs only a return visit.

Can you be muscular and fail a hydration test while properly hydrated?

Yes, and the effect has been quantified. A 2024 quantitative review pooling 171 specific gravity estimates from men and 59 from women found fat-free mass positively associated with USG — ρ = 0.36 in men, ρ = 0.57 in women, ρ = 0.38 combined. Muscle metabolism produces creatinine, urea and uric acid, all solutes that raise urine density. Because combat sports select for lean, muscular athletes, false failures in this population are systematic rather than random, and the authors call for research into fat-free-mass-specific thresholds.

Does passing a hydration test mean a weight cut was acceptable?

No, and this is the most consequential misunderstanding about the test. In a controlled study of thirteen MMA athletes losing about 5.3% of body mass with hot-water immersion, plasma volume fell roughly 14% and multiple blood markers were disturbed immediately after the protocol — and every one of them had returned to baseline by the weigh-in 24 to 26 hours later after structured rehydration. A test at the scale in a day-before format is measuring the recovery, not the cut. A pass tells you that one marker of urine concentration was below a threshold at one moment.

Why do some programmes test more than once during fight week?

Because a single test at the weigh-in is asking the question at the moment it is least likely to be answered. Blood and urine markers disturbed by an acute cut normalise within roughly a day of competent rehydration, so a scale-side test in a day-before format can be clean after a substantial cut. Repeated testing across fight week — on arrival, in the days before, and close to competition — samples the athlete at points where the state has not been undone. ONE Championship's publicly described protocol works this way, and it is a more ambitious design than a single check for exactly this reason.

Are urine test strips acceptable for hydration testing?

Not in NCAA wrestling certification, where the packet states directly that test strips are not permissible as a measuring device for specific gravity and requires a refractometer — described as the gold standard — or a urinometer. Practice differs elsewhere: some state high-school implementations describe pass/fail colour-chart screening with dipsticks or refractometers as acceptable alternatives. If you are being tested and the result will have consequences, it is entirely reasonable to ask which instrument is being used, because the answer determines how much weight the number deserves.

What is the ~90% hypohydration finding in combat sports?

Research examining urine specific gravity in Olympic combat-sport athletes has reported a universally high prevalence of hypohydration — around 90% — measured by this test, frequently in athletes whose body mass is stable. Stable mass alongside near-universal apparent dehydration suggests the threshold is reading something other than whole-body fluid deficit in this population. The same work identifies laboratory-derived benchmarks applied in field settings, inconsistent sampling, uncontrolled confounders and possible renal adaptation to habitual dehydration as reasons the method's utility here is questionable.

Can you drink your way to passing a hydration test?

Fluid intake in the hours before a sample is one of the recognised confounders of the measurement, which is why the NCAA prevents an immediate retest by requiring a wait of not less than 24 hours after a failure. That provision exists because a test that can be retaken in an hour measures the last hour. The broader point is that optimising the number rather than the state it represents defeats the purpose of testing entirely, and any protocol built around passing rather than around being hydrated has inverted the exercise.

Does hydration testing stop weight cutting?

No programme claims it does, and the evidence does not support the claim. What testing can do is make gross, sustained dehydration visible early enough to interrupt an irreversible decision — which is exactly what NCAA certification uses it for — and, where testing is repeated across fight week, make an aggressive acute cut harder to conceal. What it cannot do is establish that any individual athlete is adequately hydrated at a given moment, because the instrument does not have that resolution in this population.

What is the difference between a hydration gate and a hydration verdict?

A gate delays a decision: fail, return later, lose an afternoon. A verdict ends a competition: fail, and the fight does not happen. The same test with the same error rate is defensible in the first role and much harder to justify in the second, because a two-in-three false-failure rate that costs a wasted trip is a different proposition from one that costs a purse. Both can be reasonable policies, but only if the error rate is stated openly rather than implied away by the confidence of the number's three decimal places.

Is there a better hydration test than urine specific gravity?

Several, and none is practical at a weigh-in. Plasma or serum osmolality is the stronger reference — the NCAA's own validation used blood fluid volume as its criterion — but requires a draw, a laboratory and a turnaround. Urine osmolality needs an osmometer. Isotope dilution measures total body water and takes hours. Bioimpedance is portable but its agreement with reference methods in acutely dehydrated athletes is not good enough to build a rule on. Specific gravity survives on being cheap, immediate and non-invasive, which is a real set of virtues and not the same as being accurate.

Should I test my own hydration during fight week?

A refractometer will tell you something, and used consistently over weeks it will tell you more than any single reading. But the most useful self-measurement is duller: body mass at the same time of day in the same conditions, tracked across a camp. That trend detects a descent going wrong long before a urine sample does, and it does not carry the muscularity bias or the confounders. The medical question of what any of it means for you specifically belongs with a physician or a registered dietitian who knows your history.

Sources

Sourced to

2025-26 NCAA Men's Wrestling Weight Management Program Packet — National Collegiate Athletic Association, 13 August 2025; hydration protocol and Supplements 8 and 9 including the threshold validation
2025-26 NCAA Women's Wrestling Weight Management Program Packet — National Collegiate Athletic Association, 2025; identical 1.020 threshold and procedure
Urine specific gravity as an indicator of dehydration in Olympic combat sport athletes; considerations for research and practice — Zubac D, Reale R, Karnincic H, Sivric A, Jelaska I, European Journal of Sport Science, 2018;18(7):920–929. DOI 10.1080/17461391.2018.1468483
Fat-Free Mass Is Positively Associated With Urine Specific Gravity in Athletes and Active Adults: A Quantitative Review — Wilson PB, Winter IP, Translational Sports Medicine, 9 December 2024;2024:8827027. DOI 10.1155/tsm2/8827027, PMID 39686918
Effect of rapid weight loss incorporating hot salt water immersion on changes in body mass, blood markers, and indices of performance in male mixed martial arts athletes — Connor J, Germaine M, Gibson C, Clarke P, Egan B, European Journal of Applied Physiology, 2022;122(10):2243–2257. DOI 10.1007/s00421-022-05000-7, PMID 35833967
Reviewing the current methods of assessing hydration in athletes — Journal of the International Society of Sports Nutrition, review of hydration assessment methods and their limitations
Rules in Place to Guard Against Weight Cutting in Wrestling — Ronshaugen N, Moffatt K, Koontz J, National Federation of State High School Associations, 5 October 2022
Wrestling Minimum Weight Certification Program Information — University Interscholastic League, Texas; state implementation of NFHS rule 1-5-1 including the 1.025 threshold
International society of sports nutrition position stand: nutrition and weight cut strategies for mixed martial arts and other combat sports — Ricci AA et al., Journal of the International Society of Sports Nutrition, 2025;22(1):2467909. DOI 10.1080/15502783.2025.2467909, PMID 40059405
Muscle contraction velocity, strength and power output changes following different degrees of hypohydration in competitive olympic combat sports — Pallarés JG et al., Journal of the International Society of Sports Nutrition, 2016;13:10. DOI 10.1186/s12970-016-0121-3, PMID 26957952
Automated Urinal-Based Specific Gravity Measurement Device for Real-Time Hydration Monitoring in Male Athletes — Frontiers in Sports and Active Living, 2022;4:921418, on the practical constraints of field hydration measurement

Plan the descent, don't guess it

Fighter Cut builds a week-by-week plan from today to your weigh-in, classifies the rate you are actually losing at, and logs what you eat against it. It does not make a cut safe — nothing does. It makes the numbers visible early enough to change them.

Open Fighter Cut

Hydration testing at weigh-ins