Women, Hormones and the Ultra Long Run
Trail Note
This Trail Note is informed by research on female sex hormones, ultra‑running and energy availability. References are included for deeper reading.
Women, Hormones and the Ultra Long Run: How Much Is Enough?
Women can and do excel at ultras. The question is not “can you go long?” - it’s how to go long in a way your hormones, bones and nervous system can actually sustain.
The same 5–6 hour training run means something very different in a body with a menstrual cycle, perimenopausal shifts or post‑menopausal hormone profiles than it does in a younger male body. Our coaching has to reflect that.
Use this Trail Note as a check‑in alongside your plan: if your cycles, symptoms or energy shift as you go longer, come back to these red flags and examples before you simply add more volume.
In this Trail Note we explore how sex hormones and energy availability shape women’s response to long runs, and why “smart enough” is a better goal than “as long as possible”.
Hormones don’t stop when you start your watch
Oestrogen and progesterone interact with virtually every system that matters for ultra‑running: carbohydrate use, fat metabolism, temperature regulation, ligament laxity, bone turnover, mood and sleep. These hormones fluctuate across the menstrual cycle and shift again in perimenopause and menopause.
Long, hard or under‑fuelled runs can amplify the stress signal in your endocrine system. For some women that shows up quickly - cycle disruptions, sleep changes, mood swings. For others it whispers for months as low motivation, “mystery” fatigue or more frequent niggles.
For example, some women notice long runs feel hotter and heavier in the mid‑luteal phase, when core temperature and breathing rate are higher, even though the pace on paper hasn’t changed.
Low energy availability and long‑run stress
Low energy availability (LEA) is when the energy left for basic body functions after exercise is too low. When this becomes a pattern, we see Relative Energy Deficiency in Sport (RED‑S): menstrual disruption, bone loss, low iron, mood changes, injuries and performance plateaus.
Women are more likely than men to develop RED‑S under endurance loads, particularly when long runs get longer, life stress is high, and fuelling doesn’t rise to match. Ultra‑long training runs without adequate carbohydrate and overall intake can quietly tip you into energy debt, especially if they sit on top of dieting, skipped snacks or “earning” food with training.
Common red flags as long‑run load climbs
| Signal | What it may indicate | Possible response |
|---|---|---|
| Cycle changes | Longer cycles, missed periods or much lighter bleeds as training and long runs increase. | Shorten long runs, reduce intensity, increase fuelling; seek medical support if changes persist. |
| Lingering fatigue | Weeks of feeling “flat” despite deloads and decent sleep. | Pull back long‑run length and frequency, add recovery days, check iron and total energy intake. |
| Frequent bone or tendon niggles | Stress reactions, recurring shin/hip/foot pain, or slow‑healing tendons under higher load. | Screen for RED‑S; prioritise strength and nutrition; use conservative long‑run ceilings. |
How we adjust long runs across the female lifespan
There’s no single “right” way to do this, but at Her Trails we are engaging and utilising the research to support women for the long haul.. Using a common backbone: consistent 2–4 hour long runs, strategic back‑to‑backs, de-loads and taper. We then flex how high and how often we go long based on age and hormonal context.
A few simple examples:
- High‑hormone luteal days: Keep the long run but drop intensity and add fuelling reminders to reduce perceived effort and calm the nervous system.
- Perimenopause: If sleep is poor and hot flushes are high, shorten long‑run duration, add strength and mobility, and build in more recovery between big weekends.
- Post‑menopause: Reduce how often you use the very longest outings, favour higher‑quality 2–3.5 hour runs, and prioritise strength, balance and fuelling for bone and muscle health.
A better long‑run question for women
Instead of “Can I handle a 6‑hour training run?”, try:
- “Will my hormones, bones and nervous system benefit from this, or just survive it?”
- “Can I recover from this in the context of my work, family and cycle?”
- “Would two well‑fuelled 3‑hour runs serve me better than one 6‑hour slog?”
Often, the strongest answer - and the one that gets you to the start line ready - is the version that looks smaller on paper and feels better in your actual life.
You don’t need to mimic anyone else’s long runs to belong in ultra spaces. You need training that takes your hormones seriously, respects your recovery, and leaves enough of you for the rest of your life. That’s the standard we aim for when we decide how much is “enough” for you, right now.
References
- Collado‑Boira et al. Influence of Female Sex Hormones on Ultra‑Running Performance.
- TrainRight. Trail and Ultramarathon Training Through Perimenopause.
- Endocrine response to ultra‑marathon in pre‑ and post‑menopausal women.
- Exercise beyond menopause: Dos and Don’ts.
- Mountjoy M. et al. Relative Energy Deficiency in Sport (RED‑S).
