Most athletes plan their carbs to the gram, then treat hydration as "drink when thirsty". On a long Comrades training run or a hot Cape Town Cycle Tour, that gap shows up as heavy legs, cramping and a pace that feels harder than it should. The missing piece is usually sodium.
Why sodium matters
Sodium helps your body hold on to the fluid you drink, keeps blood plasma volume up and supports nerve signals to your muscles. Lose too much without replacing it, and plain water alone will not fix the problem.
Everyone sweats differently
Sweat sodium varies hugely between athletes: some lose around 200–300mg per litre, others more than 1,500mg per litre. That is why one generic sports drink works for your training partner and leaves you cramping.
Signs you may be a "salty sweater":
- White salt marks on your kit, cap or hairline after training
- Sweat that stings your eyes or tastes very salty
- Cramping in hot conditions or late in long sessions
How low sodium affects performance
- Your effort feels higher at the same pace or power
- Power output drops slightly as the session goes on
- Concentration and decision-making fade
- Cramps become more likely, especially in the heat
What to do about it
- Pre-load before long or hot sessions with an electrolyte drink.
- Replace as you go – match electrolyte intake to how much you sweat, rather than waiting for thirst.
- Individualise – if you're a heavy or salty sweater, choose a higher-sodium option.
Our GO Hydro tablets make it easy to add electrolytes to your bottle, and BETA Fuel + Electrolyte combines carbs and sodium for long, hot efforts.
Adapted from Science in Sport research content for South African athletes.
