Why drinking water isn't enough
Most footballers know they need to drink during a match. What fewer realise is that drinking water alone, especially in large amounts, can actually work against you.
To understand why, you need to know what sweat actually is.
Sweat is not just water
When you sweat, you lose fluid and electrolytes. Electrolytes are minerals, mainly sodium, potassium, and magnesium, that carry an electrical charge and are essential for almost every function your body performs during exercise: muscle contraction, nerve signalling, fluid balance.
Sodium is the most important one to understand. It is the primary electrolyte in your blood and the main driver of how fluid moves in and out of your cells.
When you sweat heavily and replace that fluid with plain water, you dilute the sodium concentration in your blood. Your body detects this drop and responds by suppressing thirst and increasing urine output to bring the balance back. The result is that you can end up less hydrated than before, even though you drank.
What dehydration actually does
A fluid loss of just 2% of body weight is enough to measurably reduce endurance performance. At that level, research shows decreases in aerobic capacity, reaction time, and cognitive function.
For a 75 kg player, 2% is 1.5 litres. That is entirely achievable within a single match, particularly in warm conditions.
At higher levels of dehydration, cramping risk increases, body temperature rises faster, and the cardiovascular system has to work harder to deliver oxygen to working muscles.
The osmosis problem
Hydration is fundamentally about osmosis: the movement of water across membranes from areas of low concentration to high concentration. Your cells maintain a precise internal environment, and fluid balance depends on the concentration outside the cell matching what is inside.
When you drink large amounts of plain water quickly, you temporarily lower the sodium concentration outside your cells. Water moves into the cells to compensate. This can cause swelling in muscle cells and, in extreme cases, a condition called hyponatraemia, which is low blood sodium. In sport, it is more common than most people think, and it presents similarly to dehydration, which makes it easy to mismanage.
The practical upshot is simple: your hydration strategy needs to include sodium, not just fluid.
What effective hydration looks like
For a match, the goal is to arrive well hydrated, maintain electrolyte balance during play, and rehydrate properly afterwards.
That means sodium before and during, not just water. It means not waiting until you feel thirsty, because thirst is a late signal that dehydration is already underway. And it means understanding that the amount you need varies based on how much you sweat, which differs significantly between players.
Pitched Hydration is formulated around this. The electrolyte profile, including the sodium concentration, is built specifically for the sweat rates and duration of a football match, not a generic exercise session.