Dehydration negatively affects your running performance and slows your ability to recover. It increases muscle fatigue and exhaustion.

Early signs of dehydration include increased thirst, nausea, dry mouth, and headache. It also reduces the amount of blood your heart pumps with each beat.

Consequently, it decreases the amount of oxygenated blood delivered to your muscles resulting in less energy production and therefore reduced running pace. These effects are magnified in hot weather conditions. Maintaining a fast pace on a hot day becomes increasingly dangerous as you become progressively more dehydrated and this may lead to heat stroke.

If you’re feeling light-headed, or experiencing cramps, chills and disorientation, these are signs of major dehydration. Do not wait for the symptoms to occur before drinking water. It will be too late!

What you can do:

Always ensure that you are well hydrated before every run. The amount you need to drink varies depending on the condition, exercise intensity, metabolism, body size, and how much you perspire. Dr Pauline Leong, Head for the Department of Physiotherapy at Sengkang General Hospital (SKH), a member of the SingHealth group​ advises, “Drink as much as 5 litres of water a day to replace lost nutrients during a long run.”

Running places huge demands on your cardiovascular system; there is an increase in oxygen use by your muscles to keep running. Therefore your heart needs to work harder to meet these demands. If your body is unable to keep up with this oxygen supply not only to your muscles but also to your heart (which is a muscular organ), you may experience difficulty breathing and even pain. It can hit even healthy runners, typically due to a previously unknown heart condition.

What you can do:

Before you take up running or any other form of physical activity, have a physician clear you for strenuous activity (even if you are healthy!). Dr Pauline Leong explains, “The physician will be able to determine if you have any underlying heart problems which may be exacerbated by exercise."

Ensure that you are well hydrated and replenish electrolytes lost during exercise. If you have a regular routine of running but have been unwell with a viral infection or flu, you will need to gradually ease yourself back to your previous pace. Though you may feel fine, after days of inactivity your heart may not be ready to leap straight back into a high demand exercise routine.

It is also important to keep to a low-fat and balanced diet and gradually increase your running to prevent a sudden strain on your cardiovascular system.

Ref: P16

Check out our other articles on running:

Health Benefits of Running

Tips to Prevent Cramps During Running

Home Remedies for Common Running Injuries

6 Ways to Relieve Muscle Pain After Exercising

Tips to Train for Your First Marathon