Expert fitness trainer’s suggest that you should have a 500ml bottle of water during 60 minutes of exercise. They add that you should only sip at water if you are exercising for longer.

Everyone knows that you should keep a bottle of water handy when you're exercising, so you can replace the fluids lost through sweating. But you can actually drink too much water during a workout.

Dehydration occurs when your body loses more fluid than you take in so you need to make sure you replace the fluids lost when you sweat during exercise - while not drinking too much.

If you're exercising for a shorter amount of time, you don't need to drink a whole bottle. In fact, 200ml to 100ml of water should be enough for 30 minutes of exercise. If you are working out for longer, then you should sip at between 200ml and 300 ml - every 15 to 20 minutes to stay properly hydrated.

Hyponatremia is most commonly associated with people who compete in endurance sports, such as marathon runners, who drink too much water and then cause the sodium levels in their blood to be diluted.

Older people and those exercising in the heat, shouldn't consume more than the recommended amount, however tempting it might be. This is because when you drink too much water, your body can't get rid of the excess fluid by sweating or urination. That can result in hyponatremia, or water intoxication, which can cause headaches, vomiting, seizures and even death in some very extreme cases.