Sports Drinks Explained: Hypertonic, Hypotonic & Isotonic
Walk into any UK supermarket, and the sports drink aisle can feel like alphabet soup. Bottles, powders, “hydration tabs”… and all the things. Do you really need isotonic? What’s hypotonic? And when on earth would you drink something hypertonic?
In this blog, I’ll break it down in plain English. You’ll learn:
The difference between hypotonic, isotonic, and hypertonic drinks
When to use each type for training, recovery, or hot weather
UK examples you’ll actually find on the shelves
Signs to check if your hydration levels are on track
How to make your own budget-friendly sports drinks at home
By the end, you’ll know exactly which drink (or DIY mix) is right for you.
Right, let’s cut through the noise with a simple guide.
Why Sports Drinks Exist
At their core, sports drinks are just a mix of fluid + carbs + electrolytes. Depending on the concentration, they can:
Rehydrate you quickly
Top up your carbohydrate (energy) stores
Or do both at once
The trick is knowing which type to pick for your situation.
The Three Types of Sports Drinks
Hypotonic
What it means: Lower concentration of carbs and electrolytes than your blood.
Purpose: Rapid hydration, not much energy.
Best for: Hot weather, short workouts, or when you don’t need extra carbs.
UK Examples:
Powerade Zero
Lucozade Sport Hydro Active
DIY version: Water + a tiny splash of fruit juice + pinch of salt.
Isotonic
What it means: Similar concentration to your blood (~6–8% carbs).
Purpose: Hydration and energy. The all-rounder.
Best for: Endurance training, team sports, or anything lasting longer than 60 minutes.
UK Examples:
Lucozade Sport
SIS GO Isotonic Gels
DIY version: 200ml regular squash (not sugar-free) + 800ml water + pinch of salt.
Hypertonic
What it means: Higher concentration of carbs than your blood (>8% carbs).
Purpose: Energy first, hydration second. Absorbs slowly.
Best for: Refuelling after training or ultra-endurance events (always pair with water).
UK Examples:
Coca-Cola
SIS GO Energy Powder (when made with less water for a stronger mix)
DIY version: 500ml fruit juice + pinch of salt (sip with water on the side).
Hydration Levels: Signs You’re Drinking Enough (and When You Need More)
Sports drinks only help if you actually need them. So how do you know if your hydration levels are on track?
Signs You’re Hydrated
Pale yellow urine (think “straw coloured”)
You’re not overly thirsty
Steady energy levels during exercise
Normal sweating pattern (not suddenly more or less than usual)
Signs You May Need to Pay More Attention
Dark yellow or strong-smelling urine
Feeling dizzy, lightheaded, or unusually tired
Headaches creeping in during or after activity
Muscle cramps
Rapid heart rate or struggling more than usual in your workout
What to Do Next
If it’s mostly hydration you need → a hypotonic drink (or just water with a pinch of salt) is usually enough.
If you’re flagging on energy as well as hydration → an isotonic drink is your best bet.
If you’ve finished training and need to refuel glycogen → a hypertonic option (with water on the side) can help recovery.
DIY Sports Drinks on a Student Budget
You don’t need to spend £2 a bottle. Here are three cheap and cheerful mixes you can make in your kitchen:
Hydration (hypotonic): 1 litre water + 50ml fruit juice + tiny pinch of salt
All-rounder (isotonic): 1 litre water + 200ml squash (not sugar-free) + pinch of salt
Fuel (hypertonic): 500ml fruit juice + pinch of salt + water on the side
Pro tip: Bananas, raisins, or a slice of malt loaf + water can be just as effective as branded sports nutrition when money is tight.
At a Glance
Hypotonic = Hydration
Isotonic = Hydration + Energy
Hypertonic = Energy (with water)
Most people will get the most use from isotonic drinks. But all three have their place. And if you’re on a budget, making your own is quick, cheap, and effective.
