Triathlon Hydration & Electrolytes: What You Must Know
If you’ve ever hit the wall in a training session, cramped halfway through a race, or found yourself so dizzy you could barely take off your wetsuit after a swim, you’ve experienced what poor hydration and electrolyte management can do.
Hydration is one of the most overlooked parts of triathlon training – especially for women. We’ll meticulously plan our sessions, map out our fuelling, even colour-code our training spreadsheets, but many of us still “wing it” when it comes to how much we drink and what we put in our bottles.
And here’s the thing – hydration isn’t just about drinking water. If you’re training for a triathlon, it’s about balancing fluids with electrolytes so your body can perform, recover, and adapt.
Today, I’m going to walk you through exactly what you need to know about electrolytes and hydration – so you can train harder, recover faster, and race stronger without the dreaded mid-session crash.
1. Why Hydration is More Than Just Water
Water is essential, but on its own, it’s not enough for endurance performance. When you sweat, you lose not just fluids, but electrolytes – minerals like sodium, potassium, magnesium, and calcium.
These minerals:
Keep your muscles contracting properly
Help maintain nerve function
Regulate fluid balance
Support energy production
Prevent cramping and dizziness
The problem: Many triathletes – especially female athletes – focus only on drinking more water. This can dilute blood sodium levels, leading to hyponatraemia (low sodium in the blood) which can cause nausea, headaches, confusion, and in severe cases, collapse.
2. What Exactly Are Electrolytes?
Electrolytes are minerals dissolved in body fluids that carry an electric charge. The key players for triathletes are:
Sodium – the most important for endurance athletes. Maintains fluid balance and prevents hyponatraemia.
Potassium – supports muscle contractions and heart rhythm.
Magnesium – important for energy production and preventing muscle cramps.
Calcium – aids muscle contractions and nerve function.
Chloride – works with sodium to regulate hydration levels.
3. Why Female Triathletes Have Unique Hydration Needs
Our Pretty Strong Coaching clients often juggle high-volume training with busy careers, families, and hormonal changes across the menstrual cycle. All of these can impact hydration.
Hormonal shifts – In the luteal phase (after ovulation), body temperature rises and fluid loss can increase.
Smaller body size – Often means smaller sweat volume, but potentially higher sodium concentration in sweat.
Heat tolerance – Some women find they overheat faster in high humidity and need more proactive hydration.
4. How Much Should You Drink?
There’s no one-size-fits-all answer – it depends on your sweat rate, climate, and session length.
General guidelines for triathletes:
Before training/racing: 500ml–750ml in the 2 hours before
During training/racing: 400–800ml per hour (in hot, humid climates, up to 1L/hour)
After training/racing: Replace 150% of the fluid lost (e.g. if you lose 1L, drink 1.5L)
💡 Pro tip: Weigh yourself before and after training. Every 1kg lost = ~1L fluid loss.
5. How Much Sodium Do You Need?
Sodium needs vary massively – some athletes lose 300mg per litre of sweat, others over 1,000mg.
A good starting point:
Moderate sweater: 400–600mg sodium/hour
Heavy sweater: 800–1,000+mg sodium/hour
In Singapore’s heat and humidity, most female triathletes need to be on the higher side – especially for long rides and brick sessions.
💡 Consider sweat testing (Precision Fuel & Hydration, Gatorade Sweat Patch) to personalise your plan.
6. Pre-Training & Pre-Race Hydration
1–2 hours before:
500–750ml water with electrolytes (aim for ~300–500mg sodium)
Avoid overdrinking plain water – it dilutes sodium before you’ve even started
If you train first thing in the morning, consider a smaller 250–300ml sip with electrolytes
7. Hydration During Training & Racing
For sessions longer than 60 minutes – especially in warm or humid conditions – water alone isn’t enough.
What to aim for:
Every bottle (500–750ml) should contain 300–1,000mg sodium (adjust for your sweat rate)
Mix in carbs (30–60g/hour for sessions over 90 minutes) for combined fuelling and hydration
Alternate sips of drink with small bites of solid fuel to keep the gut happy
8. Post-Training Recovery Hydration
After long or hard sessions, your focus should be rehydration + refuelling.
Within 30–60 minutes:
500–750ml fluid with electrolytes
Include sodium in your recovery meal/snack (e.g. eggs on toast with a sprinkle of salt, miso soup, recovery shake with electrolyte tab)
💡 Remember – your body will keep replacing fluid for several hours post-session, so sip steadily instead of chugging litres at once.
9. Best Electrolyte Sources for Triathletes
On-the-go race-friendly options:
Precision Fuel & Hydration 1000/1500
SIS Hydration Tabs
Nuun Endurance
SaltStick capsules
Everyday food sources:
Sodium – table salt, soy sauce, miso, pickles
Potassium – bananas, potatoes, oranges
Magnesium – leafy greens, nuts, seeds
Calcium – dairy, fortified plant milks, leafy greens
10. Hot Climate Hydration Tips
If you train in hot, humid conditions like Singapore:
Start hydrated – check morning urine colour (aim for pale yellow)
Pre-cool with ice slushies before races
Use insulated bottles to keep drinks cooler for longer
Wear light, moisture-wicking kit
Plan your routes to pass water points if needed
11. Common Hydration Mistakes Women Make
Overhydrating with plain water – dilutes sodium and increases risk of hyponatraemia.
Not starting hydrated – skipping morning fluids before an early session.
Ignoring electrolyte needs – assuming cramps = magnesium deficiency, when sodium is often the bigger factor.
Copying someone else’s plan – your sweat rate and sodium loss are unique.
Waiting until thirsty – thirst isn’t always a reliable cue during intense training.
12. Your 3-Step Hydration Action Plan
Test your sweat rate – weigh before/after sessions.
Match sodium intake to your sweat losses – start with 500–750mg/hour and adjust.
Practise in training – never try new drinks or capsules on race day.
Final Thoughts
Hydration and electrolytes can be the difference between feeling strong at the finish line and being slumped on the kerb with your head between your knees.
For female triathletes – especially those balancing busy lives, hormonal fluctuations, and tough training – getting this right is essential.
The goal isn’t just to avoid dehydration. It’s to optimise performance, protect recovery, and feel confident in every training session and race.
So grab your bottle, add your electrolytes, and let’s make sure your next brick session is strong from the first pedal stroke to the final run stride.
Ready to Train Smarter, Recover Better & Perform Stronger?
At Pretty Strong Coaching, we help busy women like you fuel properly, train with purpose, and recover like pros - even with a hectic schedule. Whether you’re chasing your first half-marathon or training for your next triathlon, we’ve got you covered.
Want personalised support from a coach who understands endurance, hormones, and real life? Let’s chat and build a plan that works for you.
RELATED POSTS
