Part One: Hydration in Sport - The Truth Athletes Need to Hear
When it comes to peak performance, hydration is often misunderstood. What feels like fatigue, poor coordination, or low fitness is frequently just physiological, and preventable, dehydration. Let’s start by busting some myths: not everything that looks like hydration actually hydrates.
What Doesn't Work (And Why):
- Soft drinks
- Coffee and tea (can contribute to dehydration)
- Alcohol (dehydrates you)
- Juice (especially processed, not cold-pressed)
- Most sports drinks
Why?
- Sugar spikes insulin → energy crash
- High-concentration drinks slow gastric emptying and force the body to pull water from internal reserves to dilute them.
- Carbonation slows absorption.
The result: What feels like “low fitness” is often poor hydration. This is physiological, and completely preventable.
The Non-Negotiable Baseline:
Your body is 70–80% water, and every chemical reaction depends on it. The daily minimum for most people is 2–3 litres. If you consistently get less, the body begins to pull from internal reserves, leading over time to chronic dehydration. Long-term consequences include slower recovery from injury or illness, increased susceptibility to illness, and even chronic injuries.
The body prioritises survival: water is directed to the brain, heart, lungs, liver, and kidneys first. Critical systems for athletes, muscles, joints, digestive system, and skin, take a backseat when hydration is low.
The Dangerous 2% Drop-Off:
In the medical system there are considerable health and wellbeing impacts seen when there is a 2% dehydration reached in the body. 2% dehydration is equivalent to a loss of just 2% of your body weight in fluid.
For example:
- 70 kg athlete → 1.4 litres lost
- 90 kg athlete → 1.8 litres lost
This level can occur in under an hour of high-intensity exercise or heat. At 2% dehydration, performance suffers: reduced sprint repeat ability, slower reaction speed, poorer motor control and concentration, and impaired decision-making and emotional control. It’s the difference between winning and fading, clarity and costly mistakes.
Dehydration vs. Blood Alcohol Levels:
To put it in perspective, a blood alcohol level of 0.05 impairs reaction time, coordination, and judgment. 2% dehydration produces similar effects, slower reactions, reduced focus, and poorer decisions. The physiological mechanisms differ, dehydration reduces blood volume and brain efficiency, whereas alcohol suppresses the nervous system, but the performance outcome is nearly identical.
