Every training session takes effort, and effort means output. The harder you push, the more fluids and minerals you sweat out, and summer heat makes you lose them even faster. What goes out needs to be put back in, and that starts before your workout, not just during it. Show up already hydrated and you'll feel the difference.

Summer heat pushes your sweat rate up, and sweat takes sodium, potassium and magnesium out along with the water. Plain water replaces the fluid but not those minerals, which is why a hydrating powder with electrolytes often does more for hot-weather training than another bottle of water. 

At Nutritional Performance Labs (NPL), we've put this guide together to help you train through the heat. Below, we cover why summer in South Africa changes what your body needs, what electrolytes do when you train, the signs of dehydration that are easy to miss, how to choose the right hydrating powder and how to build hydration into your summer routine.

Why Does Summer Heat Change Your Hydration Needs?

Your body cools itself by sweating, so the hotter it gets, the more you sweat to keep your core temperature in check. Sweat rates vary from person to person, but in serious heat many people lose more than a litre of fluid an hour, and every one of those litres carries minerals out with it. The same workout that felt comfortable in winter can leave you running on empty in midsummer.

Where you train in South Africa makes a difference too. Humid coastal conditions in Durban and along the KZN coast slow down how quickly sweat evaporates, so your body keeps sweating in an effort to cool down. Dry Highveld heat in Johannesburg and Pretoria works the other way. Sweat evaporates so quickly that you barely notice how much you're losing, which makes it easy to underestimate.

Timing matters as well. Your body does adapt to training in the heat, but consensus recommendations on training and competing in the heat suggest it takes repeated sessions over one to two weeks to get there. That makes October and November, the first properly hot months of the season, the point where most people get caught out.

What Do Electrolytes Do During Exercise?

Electrolytes are minerals that carry an electrical charge once they dissolve in your body's fluids. They control where water goes in your body and keep your muscles and nerves communicating, which is why running low on them shows up so quickly during a workout.

• Sodium is the mineral you lose most of in sweat, and it's the one that helps your body hold on to the water you drink. It also drives thirst, so low sodium can leave you drinking less than you need.
• Potassium works alongside sodium to balance fluid inside and outside your cells, and it plays a key role in every muscle contraction.
• Magnesium supports muscle function, nerve signalling and the energy production your muscles rely on through a long session.

This is why more water isn't always the answer. Drinking large amounts of plain water without replacing sodium dilutes the sodium you have left, which makes it harder for your body to hold onto the fluid you're giving it. Drinks containing electrolytes and carbohydrates can offer benefits over water alone in certain conditions, according to the American College of Sports Medicine's position stand on exercise and fluid replacement. Long, hot sessions are one of the clearest examples.

Signs of Dehydration That Are Easy to Miss

You won't always feel thirsty when you're dehydrated. In summer, these are often the first signs that water alone isn't keeping up. 

• Your urine is dark yellow first thing in the morning or after training, rather than a pale straw colour.
• You weigh noticeably less after a session than before it.
• You hit an afternoon slump, lose focus or get a headache on training days, but feel fine on rest days.
• Your heart rate runs higher than usual at the same pace or effort when it's hot outside.
• Your sleep and recovery take a knock after outdoor sessions, even though your training load hasn't changed.

How to Choose a Hydrating Powder for Summer Training

The right hydrating powder comes down to how long you train and where. 

• A short gym session on a hot day. For anything under an hour, you mostly need to replace the sodium you sweat out, without extra sugar. A sugar-free hydrating powder mixed into your usual bottle covers this.
• A long outdoor session. Once you're past 90 minutes on a run, ride or hike, your body needs energy as well as electrolytes, so a powder with added carbohydrates makes more sense.
• Hot days away from the gym. Summer heat keeps you sweating on rest days too, especially if you work outdoors or spend the day in the sun. A daily electrolyte supplement helps you start your next session topped up.

Hydrolytes (Sugar Free Electrolytes) is the everyday pick in our range. Each Hydrolytes sachet gives you 500mg of sodium alongside potassium, magnesium and coconut water powder, with zero sugar, and mixes into 500 to 700ml of cold water.

For long outdoor sessions over 90 minutes, Hydrade Rapid Isotonic adds 20g of carbohydrates to its electrolytes, so you're topping up energy and fluids at the same time on a long run, ride or hike.

Whichever one you choose, read the label. Every NPL product lists each ingredient and its exact dose under our Full Label Transparency standard.

Shop Hydrolytes.

How to Build Hydration into Your Summer Training Routine

Hydration works best as a daily habit rather than something you scramble to fix once a session has already gone wrong.

• Through the day. Sip water steadily from the morning onwards so you start every session topped up, rather than downing a litre in the car park.
• Before training. Mix a Hydrolytes sachet 20 to 30 minutes before any outdoor or longer session, so you start ahead and don't spend the session playing catch-up.
• During training. Keep sipping through any session over an hour or in serious heat. For long rides, runs or races, switch to Hydrade Rapid Isotonic to cover your energy needs as well.
• After training. Replace what you've lost alongside your post-workout meal. Weighing yourself before and after a session gives you a rough idea of how much fluid you need to put back.
• Early mornings. You wake up partly dehydrated after a night's sleep, so have a glass of water, or an electrolyte drink on hot days, before a morning session.

Hydration is one part of a strong summer routine. Find out which supplements you're going to be reaching for all summer in Your New Summer Supp Stack.

Your Summer Hydration Game Plan

In summer heat, you sweat out more fluid and minerals, so you need to put more back in. Hydrate before your session as well as during it, replace what you lose afterwards, and you'll keep performing through the hottest months of the year. NPL's Hydrade range is built for exactly this, with hydrating powders that give you electrolyte support for hot-weather training. Shop NPL's Hydrade hydration range in South Africa and go into every summer session already hydrated.

Frequently Asked Questions

Do I need electrolytes if I'm already drinking enough water?

Not always. Water replaces the fluid you sweat out, but not the sodium and other minerals that go with it. For sessions over an hour or in summer heat, a hydrating powder with electrolytes helps your body hold on to the water you drink.

What are the signs of dehydration during a workout?

Dizziness, a dry mouth, tiring earlier than usual, and a heart rate that keeps climbing at the same effort are the most common signs. If you notice them, ease off, get into the shade and drink fluids with electrolytes.

What's the difference between a hydration powder and a sports drink?

A hydration powder lets you control the dose and the sugar, and it usually costs less per serving. A sports drink is more convenient, but many have more sugar and less sodium than a powder.

Should I hydrate differently for outdoor training in summer?

Yes. Start hydrating earlier, add electrolytes to at least one bottle and train in the cooler morning or evening hours where you can. Give your body one to two weeks to adjust to the heat before your hardest sessions.

How much water should I drink when training in the heat?

It depends on how much you sweat. Weigh yourself before and after a session, since every kilogram you lose is roughly a litre of fluid, and aim to keep that loss under 2% of your bodyweight.