Denver's Best Sports Physical Therapy
Strength and Performance Coach at UNITE.rehab.perform | CSCS Certified | Specializing in Youth Athletic Development and Long-Term Performance Training
This is a conversation that does not happen often enough in youth and competitive sports. And when it does happen, it usually happens too late.
The Female Athlete Triad is a medical condition involving three connected issues: low energy availability, menstrual dysfunction, and decreased bone mineral density. It most commonly affects physically active girls and women who are not consuming enough energy to support both their training and normal body function.
What makes it dangerous is not complexity. It is how quietly it develops. An athlete starts training harder. Eating stays the same or drops. Energy dips. Periods become irregular or disappear. Bones weaken. And because the athlete is still showing up, still competing, still pushing through, everyone around them assumes things are fine.
They are not fine. And by the time a stress fracture or a significant performance drop forces the conversation, the condition has often been building for months or longer.
As a coach who works with young athletes every day, I see the early signs of this before most people realize anything is wrong. And I want every parent, coach, and athlete reading this to know what to look for.
This is the root of everything. When an athlete is burning more energy than they are taking in through food, the body starts making choices about what it can and cannot support. Training gets prioritized. Normal body functions do not.
This is not always about eating disorders. In fact, many of the cases I see have nothing to do with intentional restriction. It is an athlete who trains six days a week, has a full school schedule, grabs a granola bar between practice and homework, and genuinely does not realize they are running on half the fuel their body needs.
What I actually see in the weight room and on the field when this is happening:
These are not signs of overtraining. They are signs of underfueling. And the difference matters because the solution is completely different.
When energy intake is not meeting demand, the body pulls back on hormone production. Estrogen drops. The menstrual cycle is one of the first systems affected.
Periods may become irregular, lighter, or stop altogether. That last one, amenorrhea, is the signal that gets the most attention. But irregular cycles that were previously consistent are just as important to pay attention to.
Here is where I need to be direct: a missed period is not a badge of hard training. This is one of the most harmful myths in athletics, and it persists because people do not challenge it loudly enough. If a young athlete stops getting her period or her cycle becomes unpredictable alongside heavy training, that is her body saying something is wrong. It needs to be evaluated, not normalized.
Signs that warrant attention:
Estrogen plays a direct role in keeping bones strong. When hormone levels drop and energy remains insufficient, bone density decreases. Bones become more fragile and significantly more vulnerable to stress fractures.
This is the component with the longest-term consequences. Some degree of bone density loss in a developing athlete may not be fully reversible. That is not something anyone wants to learn after the fact.
What this looks like in practice:
When I see a young female athlete with a second or third stress fracture in a 12-month window, the conversation immediately shifts from “how do we treat this injury” to “what is driving this pattern.” The fracture is the symptom. The underfueling is the cause.
One of the most important things to understand is that an athlete does not need to show all three components to be at risk. The triad exists on a spectrum. An athlete can be in the early stages of energy deficiency without having missed a single period yet. She can have irregular cycles without a stress fracture. Each warning sign matters on its own because it tells you which direction things are heading.
Waiting until all three components are fully present before taking action is waiting too long.
The Female Athlete Triad has been the recognized clinical framework for decades, and it remains a useful model for understanding the core relationship between energy, hormones, and bones. But sports medicine has evolved.
The International Olympic Committee (IOC) now uses a broader framework called Relative Energy Deficiency in Sport, or RED-S. RED-S is a condition caused by low energy availability that affects multiple body systems, including metabolism, hormones, bone health, immunity, cardiovascular function, and athletic performance. It recognizes that the consequences of underfueling reach further than three components and affect male athletes as well.
Female Athlete Triad | RED-S |
Applies to female athletes | Applies to both male and female athletes |
Three primary components | Multiple body systems affected |
Focuses on energy, hormones, and bones | Includes cardiovascular, immune, metabolic, and psychological impacts |
Older clinical framework | Current model endorsed by the IOC |
Both terms matter. Parents and coaches should be familiar with both. The triad gives you a focused lens for understanding the three most visible consequences. RED-S reminds you that the damage from underfueling does not stop there.
Any active athlete can develop the triad or RED-S, but certain sports and environments carry higher risk:
But the sport alone does not create the risk. The environment does. Teams where coaches comment on weight, where food restriction is normalized, where missed periods are treated as expected, those are the environments where the triad thrives. Culture matters as much as sport type, and often more.
Because the triad spans multiple systems, diagnosis requires more than a single test:
Medical history. Understanding training volume, nutrition habits, injury patterns, and any concerns around body image or eating behaviors.
Menstrual history. Tracking cycle regularity and identifying disruptions, including delayed onset in younger athletes.
Nutrition assessment. Evaluating whether current energy intake matches the demands being placed on the body. This does not require a formal eating disorder diagnosis. Unintentional underfueling is just as damaging.
Bone density testing. DEXA scans can identify reduced bone mineral density before stress fractures occur.
Movement and injury assessment. Evaluating whether recurring injuries, especially stress fractures, are connected to an underlying energy or hormonal deficiency.
The most effective diagnostic approach is multidisciplinary: physicians, dietitians, sports psychologists, and physical therapists each see a different piece of the picture. Together, the full pattern becomes clear.
At UNITE, we are often the first point of contact when an athlete shows up with a stress fracture, recurring injuries, or a performance decline they cannot explain. That puts us in a unique position to recognize patterns that point toward the triad before anyone else does.
Here is what our role looks like in practice:
Connecting the dots. When a 16-year-old runner comes in with her third tibial stress fracture in 18 months, we are not just treating the bone. We are asking the questions that lead to the bigger conversation. Training volume, fueling habits, menstrual history, recovery patterns. The injury brought her through the door. What we find underneath determines where the treatment goes.
Rebuilding safely. Athletes recovering from triad-related injuries need strength work, but it has to be dosed intelligently. We rebuild capacity progressively, respecting where the body actually is rather than where the athlete wants it to be.
Structuring the return to sport. Coming back from a stress fracture with underlying energy deficiency is not the same as coming back from a standard overuse injury. The return-to-sport plan has to account for bone health, current strength levels, and whether the factors that caused the injury have actually been addressed.
Collaborating across disciplines. We work alongside physicians, dietitians, and other healthcare professionals to make sure training demands, nutrition, and recovery are aligned throughout the process. Physical therapy in isolation is not enough for this condition. It takes a team.
Yes. And the earlier intervention begins, the better the outcome.
Early recognition, improved nutrition, appropriate training modifications, and a multidisciplinary healthcare team can help restore energy balance, normalize menstrual function, improve bone health, and safely return athletes to sport.
Recovery is not just about eating more. It involves recalibrating the relationship between what the body is being asked to do and what it is being given to do it with. It often involves addressing beliefs and habits around food and body image that have been reinforced for years. It takes professional support, honest conversations, and patience.
But athletes who are identified and supported early, before significant bone loss or prolonged amenorrhea develops, typically recover fully and return to sport stronger and more resilient than they were before.
Can athletes develop the Female Athlete Triad without having an eating disorder?
Yes, and this is one of the most important misconceptions to clear up. Many cases are driven by unintentional underfueling. An athlete with a demanding training schedule who simply does not eat enough to match their energy output can develop the triad without any disordered relationship with food. The absence of an eating disorder does not mean energy availability is adequate.
Is missing a period normal for athletes?
No. Full stop. Despite how commonly this is dismissed in athletic culture, amenorrhea is a clinical signal that the body is not getting enough energy to maintain normal function. It should always be evaluated. Any coach, parent, or athlete who has been told that missed periods are “just part of training hard” has been given bad information.
Can boys develop RED-S?
Yes. The Female Athlete Triad specifically applies to female athletes, but RED-S affects both male and female athletes. Male athletes with low energy availability can experience hormonal disruption, decreased bone density, impaired immunity, and reduced performance. The conversation is broadening, and it should be.
What sports carry the highest risk?
Sports that emphasize leanness, aesthetics, or weight-based categories tend to carry the highest risk. Distance running, gymnastics, dance, cheerleading, wrestling, and rowing are among the most commonly affected. But the sport is only part of the equation. The team culture, coaching environment, and individual pressures around body image matter just as much and often more.
Whether you are a competitive athlete recognizing these signs in yourself, a parent noticing changes in your daughter, or a coach trying to do right by the athletes you work with, early intervention is the most powerful tool available.
This is not about overreacting. It is about paying attention. The athletes who get the best outcomes are the ones whose support system, coaches, parents, and healthcare providers, had the awareness and the willingness to have the conversation before things progressed.
If you are concerned that you or your athlete may be showing signs of the Female Athlete Triad or RED-S, our team can assess movement quality, training patterns, injury history, and recovery strategies while collaborating with other healthcare professionals when appropriate. We would rather have the conversation early and find out everything is fine than have it late and wish we had started sooner.
Coach Francis, CSCS, is a Strength and Performance Coach at UNITE.rehab.perform in Thornton, CO, specializing in youth athletic development, explosive power training, and long-term performance programming for athletes at every level.
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