Is there a correlation between adolescent athletes who suffer from RED-S and peak bone mineral density?

Yes.

And it is one of the reasons RED-S in adolescent athletes needs to be taken seriously.

Adolescence is not just another training phase. It is a critical window for building bone.

If an athlete spends that window under-fuelled, hormonally disrupted, injured, overloaded, or missing normal growth and development signals, there can be consequences for bone mineral density.

Some of those consequences may extend well beyond the current season.

Why adolescence matters

Peak bone mineral density, or peak bone mass, is built mostly during childhood, adolescence and early adulthood. Around 90% of bone mass is accumulated by approximately 18 years of age, with peak bone mass generally reached by the late twenties.

That means the teenage years are not just about performance.

They are about construction.

The skeleton is meant to be building. If the body is not given enough energy, nutrients, hormones, recovery and appropriate loading, that construction process can be compromised.

What is RED-S?

RED-S stands for Relative Energy Deficiency in Sport.

It occurs when there is not enough available energy to support both exercise and normal physiological function. The International Olympic Committee describes RED-S as a syndrome involving impaired physiological and/or psychological functioning due to problematic low energy availability.

In adolescents, this is especially concerning because the athlete is not just training.

They are growing.

Growth costs energy.
Puberty costs energy.
Bone development costs energy.
Training costs energy.
Recovery costs energy.

If intake does not meet the combined demand, something has to give.

How RED-S can affect bone

Low energy availability can affect bone through several pathways.

It can reduce the energy available for bone remodelling.
It can alter hormonal function.
It can disrupt menstrual function in females.
It can affect testosterone and other endocrine markers in males.
It can impair recovery.
It can increase risk of bone stress injury.

The older Female Athlete Triad model described the relationship between low energy availability, menstrual dysfunction and low bone mineral density. RED-S is a broader model that includes both females and males, and more body systems, but bone health remains central.

This is not theoretical.

Research in adolescent athletes has shown concern around low bone mass during the very period when bone should be accruing rapidly. One longitudinal study of adolescent male elite athletes reported that 38% had low bone mass at baseline during the peak window for optimal BMD accrual.

That is a serious finding.

Female athletes: menstrual function matters

In adolescent female athletes, menstrual function is a key clinical sign.

Irregular periods, delayed onset of menstruation, or loss of periods should not be dismissed as “normal because she trains hard”.

It may be a sign that the body does not have enough available energy.

This matters because oestrogen plays an important role in bone health. If menstrual function is disrupted during adolescence, the athlete may miss part of the normal bone-building window.

Studies in the Female Athlete Triad literature have consistently shown lower bone mineral density in amenorrhoeic athletes compared with eumenorrhoeic athletes.

In plain language: if periods disappear, we need to ask why.

Male athletes are not exempt

This is equally important.

RED-S is not just a female athlete problem.

Male athletes can also experience low energy availability, hormonal disruption, reduced testosterone, poor recovery, low mood, fatigue, recurrent injury and impaired bone health.

This is particularly relevant in endurance sports, weight-category sports, aesthetic sports, and any environment where leanness is rewarded.

A teenage male runner who is always tired, under-eating, getting stress reactions, and trying to stay extremely lean should raise concern.

The trap: performance may improve before it declines

RED-S can be hard to spot because early on, the athlete may perform well.

They may get lighter.
They may run faster.
They may look disciplined.
They may receive praise.
They may believe the strategy is working.

But short-term performance does not always equal long-term health.

Eventually, the system may push back.

Fatigue.
Mood changes.
Recurrent illness.
Bone stress injury.
Poor recovery.
Hormonal disruption.
Performance plateau.
Loss of motivation.

By the time a stress fracture appears, the problem may have been building for a long time.

What should coaches and parents watch for?

Pay attention to patterns.

Repeated bone stress injuries.
Menstrual irregularity.
Delayed puberty.
Low libido in males.
Constant fatigue.
Irritability or low mood.
Fear of weight gain.
Rigid food rules.
Training beyond the plan.
Poor recovery.
Frequent illness.
Declining performance despite more training.
Obsession with leanness.

One sign alone may not confirm RED-S.

But it should start a conversation.

What needs to happen?

The answer is not simply “stop sport”.

Sometimes training does need to be modified, especially if there is a bone stress injury or significant medical concern. But the long-term goal is to restore the athlete, not remove their identity.

The pathway usually includes:

Medical assessment where needed.
Dietitian input.
Restoring energy availability.
Monitoring growth and hormonal health.
Managing training load.
Strength training.
Appropriate impact loading.
Psychological support if food anxiety or body image concerns are present.

For adolescent athletes, the team around them matters.

Parents, coaches, doctors, dietitians, physiotherapists, biomechanists and strength coaches all need to understand that performance and growth cannot be separated.

The bottom line

Yes, adolescent RED-S can be associated with compromised bone mineral density and failure to optimise peak bone mass.

That matters because adolescence is the window where the skeleton is meant to be built.

If we miss that window, we may not fully get it back.

That is not said to scare people.

It is said because the solution is often very practical:

Fuel the athlete.
Protect growth.
Respect recovery.
Strength train appropriately.
Do not glorify leanness.
Investigate recurrent bone stress injuries.
Take menstrual changes seriously.
Remember that male athletes are also at risk.

The best young athletes are not just fit.

They are well built.

References

Mountjoy M et al. 2023 International Olympic Committee’s consensus statement on Relative Energy Deficiency in Sport — REDs. British Journal of Sports Medicine, 2023.

Ackerman KE et al. Bone health and the female athlete triad in adolescent athletes. 2011.

Stenqvist TB et al. Relative Energy Deficiency in Sport indicators in male adolescent elite athletes. 2023.

Birch K. Female athlete triad. BMJ, 2005.

Sopher AB et al. An update on childhood bone health: mineral accrual, assessment and treatment. 2015.