Bone Stress Injuries and Low Energy Availability

Bone stress injury develops when repetitive loading and the body’s capacity to repair bone fall out of balance. Low energy availability can be one contributor, but it is not a diagnosis that can be made from a symptom list, body size, or a training schedule. Focal pain during impact needs clinical assessment; treatment and return to sport depend on the injury site, severity, and the athlete’s wider health.

Bone stress injury: load and repair in tension

Bone continually responds to the forces placed on it. Repeated sport or training loads create microscopic damage as part of normal remodeling. A bone stress injury develops when microdamage accumulates faster than it can be removed and repaired. The 2025 international Delphi consensus treats bone stress injury as a continuum: continued loading can progress tissue weakening toward a partial or complete fracture. This is one reason early evaluation matters when pain is focal and repeatedly returns with impact.

Training load is one part of the story. A recent increase in duration, intensity, frequency, hills, surface, or sport-specific repetition can increase mechanical demand. Recovery, prior injury, biomechanics, sleep, nutrition, and health conditions can change how well bone adapts. There is no single training error that explains every case, and an injury can occur without a dramatic recent increase.

Low energy availability is broader than “not eating enough”

Energy availability describes energy left for normal body functions after exercise expenditure is accounted for. The IOC defines relative energy deficiency in sport (REDs) as impaired physiological or psychological functioning associated with problematic, prolonged or severe low energy availability. Outcomes may involve reproductive function, bone and other musculoskeletal health, immunity, metabolism, cardiovascular and blood health, well-being, and performance. The framework includes female and male athletes, although the evidence base and presentations differ between sexes (Mountjoy et al., British Journal of Sports Medicine, 2023).

Low energy availability is not automatically the same as REDs. The IOC distinguishes short-term, potentially adaptable changes from more persistent problematic exposure, with effects moderated by individual characteristics and context. An athlete’s body size, a particular meal, or one period of heavy training cannot settle that question. Some athletes may not recognize symptoms or may have difficulty describing them; a careful and respectful clinical conversation matters more than blame.

Energy availability can become low unintentionally: appetite may not match a sudden rise in training, travel and competition can disrupt meals, food access may be limited, or illness and stress may change intake. It can also occur alongside intentional restriction, pressure to meet a weight category, or disordered eating. These pathways have different personal contexts, but any pattern that leaves health and recovery compromised warrants support rather than judgment.

What an injury evaluation looks at

Bone stress injury is not diagnosed by an online checklist or by hopping on one leg. The international consensus describes a clinical workup that combines history, physical examination, and imaging. Clinicians ask about where and when pain began, how it changes during activity, recent training, previous injuries, health history, medications, menstrual or reproductive changes when relevant, nutrition, and recovery. The exam and imaging choices depend on the location and suspected severity.

Plain radiographs may be used initially, but early bone stress changes can be difficult to see. The 2025 Delphi panel described MRI as the imaging modality of choice for many clinicians; the clinician decides whether imaging is needed and what type is appropriate. MRI findings also need to be interpreted with symptoms and examination. The same scan finding can have different meaning in different contexts, and not every athlete needs routine imaging while injury-free.

Some locations have greater risk of progression or healing complications. The 2025 consensus identified superior femoral-neck cortex, anterior tibial cortex, navicular, and base of the fifth metatarsal as high-risk sites. Persistent groin, shin, or midfoot pain during impact should not be tested by continuing to train. If pain is severe, worsening, present at rest, or affects weight-bearing, seek prompt medical care. Suspected high-risk injury deserves timely clinician assessment.

REDs is assessed by a team, not inferred from one clue

The IOC’s REDs Clinical Assessment Tool version 2 (CAT2) was introduced to help qualified clinicians assess accumulated indicators and stratify risk. It does not turn one missed period, low testosterone, low energy, or prior fracture into a diagnosis by itself. The tool is intended for clinical use within a multidisciplinary process that may involve sports medicine, nutrition, mental health, and other specialties. A physician or qualified clinician considers other explanations for symptoms and uses the whole record.

For coaches, teammates, and families, a useful first move is to support access to confidential care rather than monitor food or demand a specific body shape. An athlete should not have to wait for a fracture before discussing recurrent injuries, fatigue, performance decline, menstrual disruption, loss of libido, mood changes, or stress about eating and weight. Those signs can have multiple causes; they are reasons to talk with a professional, not a REDs scorecard.

• 🧑‍⚕️ Ask about a sports-medicine assessment. A clinician can evaluate pain and decide whether imaging or a broader health workup is needed.
• 🤝 Invite nutrition support without blame. A sports dietitian can help assess fueling needs in relation to training and recovery.
• 🧠 Include mental health expertise when helpful. Restriction, anxiety, or disordered eating may need care from professionals experienced in those issues.

Treatment and return to sport are individualized

Management depends on where the injury is, its severity, whether weight-bearing is safe, and the athlete’s overall health. The Delphi consensus describes options that can include activity modification, protected weight-bearing, immobilization, physical therapy, nutritional counseling, and, in some cases, surgery. That range is why a general “run through it” rule or a universal rest duration would be unsafe. Clinicians determine the plan and monitor response.

When low energy availability is part of the picture, treating the painful site alone may not address the conditions that impair recovery. The IOC recommends prevention and treatment approaches that improve energy availability and address the health and performance effects of REDs. This may require temporarily changing training, increasing or better distributing nutrition, and managing associated medical or psychological concerns. A single supplement or one laboratory result does not stand in for that work.

Return to sport is a staged clinical decision informed by symptoms, function, tissue healing, injury site, and the athlete’s health—not a calendar promise. Exercise is not a substitute for fracture rehabilitation, clinician-directed activity restriction, or treatment of low energy availability. The exercise injury-prevention topic addresses general progressive training; it does not replace the specific care of a diagnosed bone stress injury.

Questions, answered briefly

• 🩻 Can a hop test confirm a stress fracture? No. A self-test cannot identify site or severity; diagnosis combines clinician assessment and appropriate imaging.
• ⚖️ Does a normal body weight rule out REDs? No. Body size alone cannot confirm or exclude problematic low energy availability.
• 🏃 Should I train through focal pain? Do not use this page to clear yourself. Stop impact that provokes focal pain and arrange clinical assessment, especially for severe or worsening symptoms.

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