Hydration, Fuelling & Heat for Women
Sims' hydration-physiology playbook for endurance and heat: get sodium and fuel right around training so you actually perform, instead of sipping plain water and bonking.
Pre-load with a higher-sodium drink for long or hot sessions A sodium-forward hydration mix before training; Sims notes a standard sports drink is too low in sodium to help
Sodium pulls fluid into the bloodstream and supports plasma volume and heat tolerance.
For sessions under an hour, water is usually enough Plain water for easy or short work; no need to over-fuel
Fuelling needs scale with duration and intensity; short sessions do not need carbohydrate drinks.
Take in fluid and carbohydrate on longer efforts In heat, aim around 10 ml fluid per kg body weight per hour (~0.16 oz per lb); add functional carbohydrate or real food
Replaces sweat losses and sustains intensity; the right amount depends on heat and sweat rate.
Rehydrate and refuel promptly Fluid with sodium plus protein and carbohydrate within 30 to 45 min
Restores plasma volume and starts recovery; women are especially sensitive to delayed refuelling.
Practise race fuelling in training Rehearse your during-session fluids and carbs in training, never debut them on race day
The gut adapts to tolerate fuel; surprising it on race day causes GI distress.
Build heat tolerance gradually Progressive exposure to training in the heat (and sauna can help) over one to two weeks
Heat acclimation expands plasma volume and improves cooling, a real and trainable adaptation.
Account for the cycle and menopause Expect higher core temperature and changed fluid needs in the luteal phase and after menopause; add sodium and cooling strategies
Plasma volume and thermoregulation shift with hormones, so fixed numbers will not fit every week or every age.
Plasma volume, sweat sodium and core-temperature control differ in women and shift with hormones, so generic male-derived hydration advice underperforms.
View sources
ROAR, Revised Edition: hydration, fuelling, and heat/cold acclimation (Dr. Stacy Sims)
Hydration Tips for Active Women Training in the Heat (Dr. Stacy Sims newsletter)
Dr. Stacy Sims: Female-Specific Exercise & Nutrition (Huberman Lab)
Not medical advice. This page is for education only and is not a substitute for professional medical care. Consult a qualified clinician before changing your health routine.
Independent curation. YourProtocol is an independent platform. This protocol is based on the publicly available work of Stacy Sims and is not created, reviewed, endorsed by, or affiliated with Stacy Sims or Author, ROAR & Next Level.
Is this for you
- Endurance athletes and long-session trainers
- Anyone training in heat
- Women who bonk or cramp on plain water
- People prepping for a race or event
Cautions
- Some of Sims' female-specific hydration claims are debated in the research; treat the sodium and fluid numbers as a tested starting point to personalise
- Very high sodium intake is not for everyone: blood-pressure, kidney or heart conditions should clear it with a doctor
- Over-drinking plain water during long events can cause hyponatraemia (low blood sodium), which is dangerous; sodium matters
- Sims sells no hydration line; the items here are generic categories, confirm any specific product yourself
- Educational only, not medical advice
Some links earn us a commission. It never affects our picks or grades. See our affiliate disclosure.