Hydration During Exercise and How Dehydration Affects Performance

Although hydration during exercise often stays in the shadow of the nutrition plan, it is one of the factors that affects performance the fastest. Losing fluid equal to just a few per cent of body weight can make effort feel harder and reduce concentration. In this article we look at how much water you should drink before, during and after training, the signs of dehydration and practical hydration habits that also take Ankara's dry climate into account.

How does dehydration affect performance?

When the body loses fluid, blood volume falls and the heart has to work harder to deliver the same amount of oxygen to the tissues. This has been reported to make fatigue set in earlier and to impair concentration and coordination. The effect becomes more pronounced in hot environments or in workouts that cause heavy sweating.

Signs of dehydration

• Dark urine instead of pale yellow or straw-coloured
• Tiring earlier than expected during training
• Headache or mild dizziness
• Dry mouth and thirst (this sign usually appears after the body has already lost some fluid)
• Muscle cramps, especially in long workouts or in hot conditions

Water needs before, during and after training

Timing	General recommendation
Before training (2-3 hours)	400-600 ml of water, gradually
During training (every 15-20 minutes)	150-250 ml of water in regular sips, without waiting to feel thirsty
Post-workout	Replacing the fluid lost; varies with how much you sweat

These figures provide a general framework; they can vary depending on factors such as your personal sweat rate, ambient temperature and training duration.

How can you estimate how much you sweat?

Weighing yourself before and after training is a simple way to estimate your approximate fluid loss; most of the weight difference after a session reflects lost fluid. For example, a drop of 0.5 kg after training corresponds to roughly 500 ml of fluid loss, and replacing this amount over the following hours is recommended.

Just water, or do you need electrolytes too?

For moderate-intensity sessions lasting no more than sixty minutes, plain water is usually sufficient and no extra supplement is needed. In workouts lasting ninety minutes or more, those causing heavy sweating or those done in hot conditions, also replacing electrolytes such as sodium and potassium can help reduce the risk of cramps and maintain fluid balance. Electrolyte drinks can be chosen in such cases; they are usually unnecessary for light daily workouts.

Common mistakes

• Drinking only when thirsty: Thirst is felt after the body has already lost some fluid; drinking at regular intervals throughout training is more effective.
• Arriving at training without drinking any water: Starting the day without fluids can mean entering the session already slightly dehydrated.
• Drinking too much: Drinking a large amount of water in a short time can, though rarely, cause a sodium imbalance; moderate, regular intake is safer.
• Counting caffeinated drinks as your only fluid source: Coffee and tea contribute to daily fluid intake but should not replace plain water on training days.

Ankara's climate and training indoors

Ankara's continental climate, with hot, dry summers and centrally heated winter interiors, makes it easy to lose fluid without noticing; because sweat evaporates quickly in dry air, you may underestimate how much you are sweating. This is even more noticeable for people running outdoors around Lake Eymir or in the METU forest in summer. At O'Wellness Beytepe too, sweating can be heavy in high-tempo classes such as cycle and HIIT in the O'Rise studio, so we recommend bringing your water bottle and drinking regularly during breaks.

The link with weight management

Drinking enough water can indirectly support weight management by promoting a feeling of fullness; sometimes thirst can be mistaken for hunger. Water is also necessary for metabolic processes to work properly. Still, water alone is not a weight-loss tool and should be considered together with overall dietary balance. Because fluid and nutrient needs vary from person to person, talking to our dietitian at O'Wellness Beytepe about your weight management goals helps you build a personalised approach.

Practical tips by type of training

In controlled, moderate-intensity sessions such as Reformer Pilates, sweating may stay relatively limited, but drinking water before and after the session should still not be neglected. In high-intensity, sweaty classes such as cycle, HIIT or Tabata, drinking regular sips throughout the session helps maintain performance. If you attend O'Ride Cycle or O'Hiit classes, make sure you have your water bottle with you.

Who should take extra care?

• People with conditions that require fluid restriction, such as kidney disease or heart failure, should keep their fluid intake within the limits set by their physician.
• Because the sense of thirst can diminish in older adults, regular drinking without waiting for thirst is recommended; signs such as mild dizziness after training should be monitored carefully in this group.
• In people who sweat heavily while also consuming large amounts of caffeine or alcohol, overall fluid balance should be monitored more closely.

If you have a particular health condition that affects fluid intake, it is important to consult your physician or dietitian.

The long-term effects of neglecting hydration

Chronically drinking too little can negatively affect not only training performance but also concentration, mood and general energy levels during the day. In people who train regularly, this can prolong recovery and lead to underperforming in later sessions. Treating hydration as an everyday habit rather than something specific to training days therefore gives more lasting results; a drinking routine built with small but consistent steps makes a difference in the long run.

Basic daily fluid needs

Regardless of training, daily fluid needs vary with body weight, activity level and climate. A commonly used practical approach is to drink about 30-35 ml of water per kilogram of body weight; however, this is only a starting point, and the extra fluid lost through sweat on training days should be added to it. The most reliable way to determine your exact needs is to consult your dietitian.

Practical ways to drink more water

• Always carrying a water bottle makes it easier to remember to drink regularly.
• Linking drinking water to routines: on waking, before each meal and before training.
• Using a simple tracking app or a bottle with measurement markings.
• Adding foods with a high water content, such as cucumber and watermelon, to your day contributes to total fluid intake.

The risks of drinking too much

Although drinking water is generally considered safe, excessive amounts reaching several litres in a short time can cause hyponatraemia, a rare but serious condition in which blood sodium levels fall too low. This risk can increase particularly in very long endurance events. That is why balanced intake based on sweat loss and thirst signals is recommended instead of a the more the better mindset.

Sample daily hydration plan (training day)

Timing	Recommendation
On waking	200-300 ml of water
With breakfast	200 ml of water
2 hours before training	400-500 ml of water
During training	150-250 ml every 15-20 minutes
Post-workout	Replacing the fluid lost (500 ml-1 litre depending on sweat)
Evening	Small, regular amounts according to thirst

This plan is a general example and should be adapted to your personal sweat rate, training duration and ambient temperature. Since your needs may change with the season and the day, it is worth reviewing the plan from time to time.

Frequently asked questions

To align your hydration and nutrition habits with your training programme, contact us via our contact page; let us create a suitable plan for you with our dietitian.

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