Wind cools your skin, so you don't feel how much you're sweating. Salt spray dries on you, the sun beats down, and before you know it you've lost a liter or two of fluid and a good amount of salt. That's when focus fades, legs feel heavy and the sketchy crashes happen.
1. How Much You Lose
- Sweat rates for active people in the heat are commonly between 0.5 and 2 liters per hour, sometimes more.
- Performance drops at about 2%: Sports-medicine guidelines (like the American College of Sports Medicine's) note that losing more than about 2% of your body weight in fluid can impair performance and thinking. For an 80 kg rider, that's 1.6 kg, easily lost in a long session.
- Salt goes too: Sweat contains sodium, and some people are "salty sweaters" who lose a lot. Replacing only water isn't enough on long, hot days.
The Simple Weigh-In Test
Weigh yourself before and after a session (in the same clothes, dried off). Every kilogram you lost is roughly a liter of fluid. Do it a few times at a new spot and you'll know exactly how much you need. To rehydrate, drink about 1.25 to 1.5 liters for every kilo lost, with some salt.
2. The Hot-Session Hydration Plan
Before
Start topped up. Clear or pale-yellow urine is a good sign. A salty meal or an electrolyte drink before a long session helps your body hold onto the fluid.
During
Keep a bottle with an electrolyte mix in the shade at your spot. Every time you land the kite for a break, drink. On long downwinders, a small hydration vest is worth it.
After
Use the weigh-in test, add a salty meal, and keep sipping through the evening. Your next session starts now.
3. What Actually Causes Cramps
The old story was that cramps come purely from dehydration and low salt. Research since the 2000s (much of it from Martin Schwellnus and colleagues) points mainly to muscle fatigue and an overexcited nervous system: a tired muscle's "stop" signals can't keep up with its "go" signals. Dehydration and salt loss can add to it, but fatigue is the big one.
- Stretch it gently when a cramp hits. That usually stops it fastest.
- Pickle juice works surprisingly fast: In a small study (Miller et al., 2010), a shot of pickle juice relieved cramps faster than water, probably through a reflex in the mouth rather than by replacing salt.
- Prevent it with fitness: Strong, well-conditioned legs cramp less. The tendon and strength work in The 100-Year Frame helps here too.
- Don't go out overpowered and under-trained at the start of a trip. Build up session length over the first days.
4. Heat Illness: Know the Signs
- Heat exhaustion: heavy sweating, headache, nausea, dizziness, weakness. Get into the shade, cool down, drink, stop riding for the day.
- Heat stroke is an emergency: confusion, hot skin, collapse. Cool the person immediately (water, shade, fanning) and call for help.
- Prevent it: Sun hat or cap between sessions, shade breaks, a long-sleeve rash guard, and riding the mornings and evenings when you can. More on sun protection in Sun, Salt & Glare.
5. Minerals Matter
Sodium is the big one in sweat, but you lose potassium and magnesium too. Fruit (bananas, watermelon, coconut water), salted food and a decent electrolyte mix cover most of it. Magnesium is also part of the DoNotAge daily sachet we take every morning, along with 14 other ingredients, and it's one less thing to think about on a kite trip. And on trips, look after your gut as well: Gut Health & the Traveling Kiter.
Ride Strong in the Heat (10% Off)
The DoNotAge daily sachet adds magnesium, CoQ10, NMN and 12 more ingredients to your morning. Pair it with real food and electrolytes on hot days. Use discount code KITEHOMIEZ at checkout for 10% off your entire order.
Shop DoNotAge →Free: The Kiter's 10-Minute Flexibility Routine
The mobility and core routine we use before and after sessions, as a free PDF. Plus new videos and posts every few weeks.
This article is for general education and isn't medical advice. Talk to your doctor before starting a supplement or a fasting routine, especially if you are pregnant, have a medical condition or take medication. Some links on this page are affiliate links: if you buy through them, we earn a small commission at no extra cost to you.