How do you stay hydrated training in summer heat in South Africa?

Why is summer training in South Africa harder?

Highveld afternoons regularly pass 30 degrees Celsius, while Durban, Lowveld and Eastern Cape coastal conditions add humidity, which stops sweat evaporating. Sweat rates of 0.5 to 2 L/h are common and can exceed 3 L/h. Even indoor gyms can be hot, especially when ventilation is poor.

How should you adapt your training?

• Choose the cool hours: early morning or after sunset. Shade and wind help.
• Acclimatise over 10 to 14 days. Start with shorter, easier sessions; your plasma volume expands, you start sweating earlier and the sweat becomes less salty.
• Reduce intensity on the hottest days rather than forcing pace.
• Dress to evaporate: light colours, a cap, loose breathable fabric.
• Pre-cool before races with cold fluids and shade.

How much should you drink?

Use thirst as the primary guide. The 2015 hyponatraemia consensus supports drinking to thirst, and about 3% body-mass loss is generally tolerable in cool to temperate conditions. A simple check:

1. Weigh yourself before and after a typical session.
2. Each kilogram lost is about a litre of sweat not replaced.
3. If you finish heavier than you started, you drank too much.

Full instructions are in how much water runners should drink.

Between sessions, drink with meals and sip through the day. Pale-yellow urine is a reasonable everyday signal; dark urine means you are behind. Do not rely on a single reading after taking B vitamins or other supplements, which can colour urine.

When do you need electrolytes?

For sessions over about 1 to 2 hours, for heavy and salty sweaters (white salt marks on kit), or when training twice a day. Sodium also improves fluid retention after sessions. At R4.63 to R5.17 for Biogen Electrolyte sachets and R4.80 to R5.30 for Lifestyle Electrolyte Fizzy tablets (October 2026), a daily sachet in heavy training is affordable, but sodium per serving is not published for these products, so read the pack. See do I need electrolytes or just water.

What are the warning signs?

• Heat exhaustion: heavy sweating, dizziness, nausea, headache, cramps, fast pulse. Stop, cool down and drink.
• Heat stroke: confusion, collapse, very hot skin or stopped sweating. This is an emergency. Call 112 or 10177, move to shade and cool the person with water and ice packs on the neck, armpits and groin.
• Overhydration (hyponatraemia): bloating, nausea, headache after drinking large amounts. See what is hyponatraemia.

Who is at higher risk?

Children and teenagers, pregnant women, older adults, people with heart or kidney disease, those on diuretics, antihistamines or blood pressure medication, and anyone recently ill should take extra care and ask a doctor about training in heat. Alcohol the night before also makes heat harder to handle.

What should you avoid?

Salt tablets as a cramp cure (they do not prevent cramps), forced drinking schedules, and energy-drink loading before sessions.

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