Physique in Athletes

Recovery
Written By Cat Hoh

A Performance Factor, Not Identity

Ask what an athlete should look like and the honest answer is that nobody has found out. A subgroup of the IOC's REDs consensus went looking, reviewed every study that tracked physique and performance over time rather than photographing both at one moment, and reported that no cut-off exists in any sport that signals a performance advantage. What they did find is that pursuing one carries a measurable cost, and that the cost lands hardest on the athletes who take the instruction most seriously.

There is no number, and people have looked

The critical review by Mathisen and colleagues deliberately excluded the cross-sectional studies most of the folklore rests on. A snapshot of elite marathoners will always show you that they are light, which tells you nothing about whether making a particular runner lighter will make them faster. So the review looked only at research that followed change over time: 29 studies, twelve of them interventions, seven longitudinal, ten prospective.

The findings are more interesting than either side of this argument usually admits.

Figure 01 / Interactive

What 29 studies found when they followed physique over time

The evidence / tap to change

What helps What's overstated Where it breaks
3.1–7.4%gains in lean mass

Increases in lean mass across that range improved performance in a range of sports: peak and average power in cycling, sprint performance, work economy, jump ability, racquet-sport skill. Adding muscle showed up more consistently in the data than losing fat did.

That holds in endurance events too, where the assumption usually runs the other way. Extra mass is not automatically a tax on performance.

No cut-offwas found, in any sport

Higher body fat did associate negatively with endurance performance. But within the same studies, training volume, training speed and previous results were of equal or greater importance in predicting what an athlete would go on to do.

Physique also did not contribute to talent identification. In the longitudinal talent work it mattered less than agility and technical skill. The build typical of an event is mostly a by-product of years of training in it, not the ticket to enter.

Very leanis where the harm turns up

The leanest athletes in the reviewed studies were more likely to experience adverse health, mood and performance outcomes, including loss of lean mass with the strength and power that goes with it, and impaired mental and cognitive performance.

Where mass reduction was attempted, health and performance survived only when the process was slow, extended, small and professionally supervised. Compressed or aggressive attempts impaired both. That is a clinical process, not a coaching one.

From Mathisen, Ackland, Burke et al. (2023), a critical review of 29 longitudinal, prospective and intervention studies by a subgroup of the IOC consensus on REDs. The evidence base is thin and skewed. Most of it sits in endurance and long-distance sport, few studies reported enough detail to check their measurement against best-practice protocols, and the variation between them ruled out any meta-analysis.

Read the three panels together and the practical conclusion assembles itself. The variable with the most consistent positive evidence is the one nobody frets about, and the variable everybody frets about has no target, no threshold, and a documented downside at the extreme.

Under-fuelling is common, and it is not a women's problem

Low energy availability is what happens when there is not enough energy left after training to run the body. It is the mechanism by which chasing a physique becomes losing a season. Gallant and colleagues pooled 46 studies covering 6,118 athletes and put prevalence at 45.1%, with a confidence interval from 40.6% to 49.7%.

The subgroup breakdown is the part worth pinning to the noticeboard. Female athletes, 44.2%. Male athletes, 49.4%. Middle and long distance runners, 43.4%. The number barely moves whichever way you cut it.

We actually found a higher prevalence of low energy availability in male athletes than in female athletes, indicating that it should be on the radar regardless of sex. Gallant et al., Sports Medicine, 2025

Take the caveats seriously. Heterogeneity was extreme, above 91%, and most estimates rest on questionnaires or self-reported food and training records, which people report badly. The true figure could sit either side of 45%. What the number does establish is that this is not a rare condition confined to one event group and one sex, which is roughly how most squads still treat it.

Disordered eating sits alongside and overlaps. A meta-analysis of 177 studies and 70,957 athletes put self-reported disordered eating at 19.2%, interval 17.0% to 21.6%. About one in five. Australia returned the highest country estimate in that analysis, though with an interval wide enough that it cannot carry much weight on its own.

What it actually costs

The case for leanness rests on an assumed performance gain. So it is worth looking at what the performance data says about athletes who arrive there by under-fuelling.

Figure 02 / Interactive

Athletes with low energy availability, against athletes without

Outcome group / tap to change

What gets worse What still looks fine

Impaired judgement OR 4.33

Over 22 days lost to illness OR 3.01

Reduced training response OR 2.13

Reduced concentration OR 2.01

Impaired bone health OR 1.72

Reduced coordination OR 1.58

Reduced endurance performance OR 1.47

Bar length shows the excess odds above 1.0, where 1.0 would mean no difference at all. The two largest effects are judgement and time lost to illness, and neither appears on a results sheet until after it has cost something.

VO₂ max no change

Peak power output no change

Anaerobic threshold no change

Overall injury risk OR 1.12, ns

When researchers deliberately induced low energy availability in trained men for two weeks, the standard aerobic testing battery did not detect it. Overall injury risk in the largest cohort was not significantly raised either.

In that same two-week study, vertical jump fell by 1.5 to 4.4 cm. Bone stress injury risk, unlike general injury risk, was elevated in most studies that examined it. Normal test results are not reassurance here.

Odds ratios from Ackerman et al. (1,000 female athletes aged 15 to 30) and Logue et al. (833 Irish athletes); induced-deficiency findings from Jurov et al. (12 trained men, energy availability cut 25% over two weeks). All collated in Gallant et al. (2025). These are separate studies with different populations, presented together to make a point about what routine testing catches, not as a single pooled analysis.

Which reframes the practical problem. An athlete can be under-fuelled, losing the cognitive and structural qualities that decide races, and still pass every test the programme routinely runs. Meanwhile a short-term drop in body mass does sometimes produce a brief lift in performance, and that is the cruellest part of the pattern, because it arrives just early enough to be mistaken for proof that the approach is working.

The risk is the culture, not the callipers

Body composition assessment gets debated as though the harm lives in the measurement. Most of it lives in what surrounds the measurement: whether results are public, how often they are taken, whether they are tied to selection, and whether anyone qualified is holding the process.

Mathisen's group surveyed 125 practitioners across 61 sports and 26 countries, repeating a survey first run a decade earlier. Some things had improved. Sport dietitians had replaced coaches as the people usually taking the measurements, and the share assessing athletes every fourth week or more often dropped from 18% to 5%. One thing had not improved. The proportion of practitioners reporting concern about a problematic focus on body composition went from 69% to 78%.

Figure 03 / Interactive

Before anyone gets measured: four gates

Stage / tap to change

Who, and why Consent In the room After the result

Three conditions make assessment a no, with no discussion. The athlete has no access to a qualified health and performance team. The athlete is under 18 and there is no medical indication. Or there are any concerns at all about eating behaviour, body image or physique anxiety.

Where none of those apply, the team and the athlete decide together whether a real rationale exists. If it doesn't, the guidance is explicit: no assessment, and put the attention on fuelling and recovery instead.

Written, documented, revocable. Explicit consent recorded before assessment, education delivered to the athlete first, and the decision rechecked regularly rather than assumed to carry over from last season.

The athlete can withdraw at any point without repercussions, including where assessment is medically indicated. Consent that costs something to refuse is not consent.

The coach should not be present unless the athlete agrees and it serves a purpose. The athlete may bring a chaperone of their choosing. A private space with controlled access, and an assessor trained to handle the psychological side of it.

The data is confidential medical data and gets stored to the same standard as medical records. Body mass can be measured blinded to the athlete where that suits them.

Results are not handed over at the moment of capture. They go to the athlete first, in private, interpreted alongside health and performance data and the known error of the method, usually by the dietitian or sport scientist.

Normative or reference values do not belong in an individual athlete's report. The athlete decides who else sees it. Repeat assessment should not normally exceed four to six times a year, and readiness gets rechecked before each one.

Condensed from the best practice recommendations in Mathisen et al. (2023), table 2, which covers the full cycle from justification through consent, method, collection, interpretation, reporting, communication and monitoring. The paper recommends against assessing athletes under 18 other than where medically indicated for growth and development, and notes that exceptional cases need team consensus and guardian consent.

Most community and club settings will not clear the first gate. That is the correct outcome rather than a shortfall. Without a health and performance team around the athlete, the answer to "should we do skinfolds" is no, and nothing is lost by it, because the same review that produced these recommendations also found no target worth measuring against.

What coaches say, and what to say instead

Language is where most of this actually happens. A coach is rarely the person holding the callipers and almost always the person whose offhand remark an athlete repeats to themselves at eleven at night. The point is not that physique becomes unmentionable. It is that the question moves from what a body looks like to what it can do and what it is running on.

Instead ofTry

  • "You're looking lean.""How's your energy been across the week?"
  • "What's your race weight?""Are you fuelling enough around the key sessions?"
  • "He's carrying a bit at the moment.""How's he pulling up the day after?"
  • "You look fit.""How's the training been sitting with you lately?"
  • "How do we get you lighter?""What does this athlete need to train, recover and adapt?"
  • "She's got the perfect build for it.""Her technical work has come a long way this season."
  • "You'll fly once you drop a couple of kilos.""Let's get a dietitian involved if you want to look at this properly."

Two rules sit underneath those swaps. Nothing about anyone's body is said in front of the group, ever. And appearance-based praise counts as a body comment even when it is meant kindly, because telling an athlete they look good in the shape they are currently in teaches them the shape is being watched, which is the lesson you were trying not to teach.

What to notice

Coaches are not diagnosing anything here, and the list below is not a checklist that adds up to a conclusion. These are the things that should prompt a quiet conversation and a referral, particularly when several appear together, or when they represent a change from how this athlete usually is.

  1. Eating that has become rigid, secretive, or organised around rules rather than around hunger and training.
  2. Preoccupation with food, weight, shape or exercise taking up more of the conversation than it used to.
  3. Training that has turned compulsive, including sessions added privately or an inability to take a rest day.
  4. Mood changes, new anxiety, irritability, or pulling away from teammates.
  5. Sleep and concentration falling away without an obvious reason.
  6. Recurring injuries, particularly bone stress injuries, or an unusually slow return from them.
  7. Dizziness, persistent fatigue, feeling cold, or ongoing gastrointestinal complaints.
  8. Changes in menstrual function, including periods becoming irregular or stopping.
  9. Weight change in either direction that nobody can account for.
  10. An athlete performing well who has quietly stopped enjoying any of it.

What follows is short. A private conversation rather than a confrontation, and not within earshot of anyone. Curiosity rather than accusation, and no comment on their body. Then a referral: a GP or sports physician, an accredited sports dietitian, and a psychologist where indicated. The Australian Athletics Disordered Eating Guidelines set out the referral and triage pathway. The job is to get the athlete into it early, not to work out first what is wrong.

Support and referral

If you are worried about an athlete, or about yourself, these are the places to start. In an emergency, call 000.

  • Butterfly Foundation National Helpline 1800 33 4673, for eating disorders and body image concerns. butterfly.org.au
  • Australian Athletics Disordered Eating Guidelines, the community referral and triage pathway. Download the guidelines
  • AIS and NEDC position statement on disordered eating in high performance sport, the framework underneath them. Read the statement
  • AIS Mental Health Referral Network, for eligible athletes, coaches and high performance staff. ausport.gov.au/ais/MHRN
  • Sports Dietitians Australia, to find an accredited sports dietitian. sportsdietitians.com.au
  • Lifeline 13 11 14, for crisis support at any hour. lifeline.org.au

One last thing about the state of this evidence, which the IOC subgroup put in their own limitations section and which deserves more attention than it gets. Almost everything known about physique and performance over time comes from endurance and long-distance sport. Almost nothing is known about throws, jumps, sprints or combined events. Few of the studies reported enough methodological detail to confirm they followed best-practice measurement protocols, and failing to follow those protocols is known to distort estimates of change badly. So the part of sport that has been most confident about how athletes should look has been running on a literature that cannot support the confidence, and which has never examined most of the events in athletics at all.

References

General information for coaches, athletes and clinicians. Not individual nutrition, medical or psychological advice. This article deliberately contains no body composition targets or reference values, and should not be used to set any.

Cat Hoh
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