Relative Energy Deficiency in Sport (REDs) in Ultra-Trail Running: Implications for Performance, Injury, and Long-Term Health
Study Details
This new review examined how low energy availability and REDs may develop in ultra-trail runners, and the potential consequences for performance, injury risk and long-term health 🔍
Here are the key findings ⬇️
Key Findings
🏃 Ultra-trail runners may be particularly vulnerable to REDs because of very high training volumes and prolonged race durations
🔥 Daily energy expenditure can exceed 3,500-5,000 kcal during heavy training, with substantially greater deficits during competition
⚠️ Low energy availability (LEA) often develops unintentionally because athletes struggle to match intake to expenditure
🍽️ Large race-day energy deficits are common and are not automatically pathological
🔄 The greater concern is repeated failure to restore energy availability during recovery, creating chronic low energy availability
🤢 GI symptoms, appetite suppression and limited food access can substantially reduce energy intake during ultra events
😴 Sleep deprivation may compound REDs risk by disrupting endocrine function, glucose regulation and recovery
⛰️ Heat, cold, altitude and environmental stress can further increase energy demands and impair fuelling
⚖️ Pursuit of lower body mass for climbing efficiency or running economy may encourage unnecessary energy restriction
🦴 Chronic LEA may reduce bone formation and increase bone stress injury risk
🩸 Female athletes may develop menstrual dysfunction, including oligomenorrhoea and functional hypothalamic amenorrhoea
🧬 Male athletes can experience reduced testosterone, libido, recovery and bone health
📉 REDs can impair training adaptation, causing athletes to stagnate or decline despite maintaining or increasing training volume
💤 Persistent fatigue, prolonged soreness and poor recovery may be early warning signs
🤒 Chronic LEA may also increase susceptibility to recurrent illness
🧠 Mood, concentration, decision-making and perceived effort may be negatively affected, which could be particularly important during long races
🏁 REDs may contribute to underperformance or race withdrawal, although direct ultra-trail evidence remains limited
📏 Normal BMI does not rule out REDs, as athletes can be significantly under-fuelled without obvious weight loss
🔍 Screening should consider training load, fuelling practices, injury history, menstrual or reproductive function, illness, recovery and performance changes
🧪 No single blood test can diagnose REDs, although hormones, ferritin, vitamin D and thyroid markers may contribute to assessment
🩻 DXA and MRI may be warranted when bone health or bone stress injury is a concern
🥗 Treatment should focus on restoring energy availability through increased intake, better carbohydrate availability and improved meal and snack structure
📉 Temporary reductions in training load may also be necessary in more severe cases
Conclusion
A “fuel for the work required” approach is particularly relevant during high-volume blocks, back-to-back long runs and post-race recovery 🔋
The key message is that chronic under-fuelling, rather than the unavoidable acute energy deficit of an ultra itself, is the major REDs concern in ultra-trail athletes ⚠️
A more fuelled athlete is a better athlete, although steps to achieving this can be challenging.
Reference
https://pubmed.ncbi.nlm.nih.gov/42544120/
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