Hydration sounds simple, but it's one of those areas where athletes can easily get it wrong.
I've seen triathletes arrive at training already dehydrated, drink too little during a long session, and then spend the rest of the day trying to catch up. I've also seen athletes carry enormous bottles and drink constantly because they assume more fluid is always better. Neither approach is ideal.
Fluid losses through sweat affect blood volume, cardiovascular strain, and your ability to regulate body temperature. Losing too much fluid during prolonged exercise can impair performance, particularly in hot conditions.
At the same time, drinking excessive amounts of plain water can dilute blood sodium and create its own problems. Individualized hydration is therefore much more useful than following a generic "drink X liters per hour" rule.
Your goal before training is not to become as hydrated as possible. It's to start normally hydrated. For most everyday sessions, regular meals and normal fluid intake throughout the day will cover most of this.
Drink normally throughout the day rather than trying to catch up at the last minute.
Pay attention to thirst and urine color as useful, but imperfect, indicators.
Avoid arriving at training feeling thirsty or obviously dehydrated.
Don't deliberately overdrink simply because you're about to exercise.
A commonly cited starting point is around 500 mL of fluid approximately two hours before exercise, although individual needs vary.
The key is to give your body enough time to absorb the fluid and get rid of any excess before you start.
This is where things become more individual. Your sweat rate can vary enormously from one athlete to another, and it can also change depending on the weather and the session itself.
A two-hour ride in cool conditions might produce relatively modest fluid losses. The same ride on a hot, humid day could produce dramatically more.
For longer sessions, I recommend that athletes learn their own sweat rate rather than guessing.
Weigh yourself before training.
Record how much you drink during the session.
Record your body weight afterward.
Account for any urine produced during the session.
Compare the difference.
You can then use that information to build a more personalized triathlon hydration strategy. During exercise, the goal is generally to limit excessive dehydration rather than replace every drop of sweat perfectly.
Sweat contains electrolytes, particularly sodium, so fluid replacement becomes more important as training duration and sweat losses increase.
For a short, easy session, plain water may be perfectly adequate. For longer sessions, especially in heat or when you're a salty sweater, electrolytes become more relevant.
Training lasts longer than about an hour.
You're exercising in hot or humid conditions.
You have a high sweat rate.
You're training or racing for several hours.
You've previously experienced headaches, cramping, or significant fatigue associated with heavy sweating.
The important point is that hydration and fuelling are connected. During long endurance sessions, a drink with carbohydrates and electrolytes can help address more than fluid loss.
If you've ever experienced the sudden loss of power and energy associated with under-fuelling, our guide to Bonking: What It Feels Like and How to Recover explains why carbohydrate availability matters during prolonged training.
Recovery hydration means replacing what you actually lost, not simply drinking as much as possible.
Replace fluids gradually.
Include sodium and other electrolytes where appropriate.
Eat a normal meal containing carbohydrate and protein.
Continue drinking normally throughout the rest of the day.
If you weigh yourself before and after training, the change gives you a useful indication of how much fluid you've lost. This can help you become much more precise with your recovery strategy over time.
For more on the bigger picture of post-training recovery, see our guide to Top 10 Best Recovery Tips for Triathletes.
Your hydration requirements can change dramatically depending on conditions. Heat and humidity increase the challenge because your body has to work harder to dissipate heat.
A training session that feels easy in cool weather can produce considerably more cardiovascular strain on a hot day. This is also why I wouldn't prescribe exactly the same hydration plan for every session.
Temperature.
Humidity.
Session duration.
Training intensity.
Sweat rate.
Clothing.
Access to fluids.
Your clothing can even influence how comfortable you feel during hot training. A lightweight, breathable triathlon kit such as the Men's AG Enduro Tri Suit can help you stay comfortable while training across all three disciplines.
|
When |
What to Focus On |
|
Before training |
Start normally hydrated |
|
During short sessions |
Drink according to thirst and conditions |
|
During long sessions |
Replace fluids and electrolytes to match sweat loss |
|
After training |
Replace remaining fluid and electrolyte losses |
|
Hot conditions |
Increase attention to sweat rate and sodium losses |
Most hydration problems come from one of a few common mistakes.
You finish every long ride several kilograms lighter and wonder why your heart rate was unusually high. Your hydration strategy probably needs work.
More isn't always better. Excessive fluid intake can be dangerous, particularly when sodium intake doesn't match the amount of fluid consumed.
Heavy sweaters can lose significant sodium during long sessions. Replacing only water may not be enough.
This is perhaps the biggest mistake of all. Train your hydration strategy, just like your pacing and nutrition. Don't arrive at your A-race and suddenly start drinking a product you've never used before.
The best hydration strategy isn't the one that works for another athlete. It's the one that works for you.
Learn your sweat rate. Pay attention to conditions. Practice drinking during long sessions and understand when electrolytes are useful.
For long training rides, having reliable kit makes that process easier too. Our women's tri suit range is designed for sustained cycling sessions where comfort becomes increasingly important.
Hydration doesn't need to be complicated. It simply needs to be individual, practiced, and appropriate to the demands of the session.
