When you drink too much water before, during or after exercise, your blood sodium concentration falls below normal. This overwhelms your kidneys, which can't remove the excess water. Cells start to absorb the water, leading to swelling in the body and a condition known as Exercise-Associated Hyponatremia (EAH).
Other symptoms include dizziness, headaches, fatigue, irritability, muscle weakness, cramping, nausea and vomiting. Runners may even become disoriented, unconscious, or experience seizures.
Drinking too much during exercise can overwhelm the body's ability to remove water. The sodium content of blood is diluted to abnormally low levels. Cells absorb excess water, which can cause dangerous swelling in the brain.
To hydrate before a marathon, try drinking two 8-ounce glasses of water or sports drink exactly two hours before the run starts so that by the time the race begins, the fluids will have been absorbed into your system.
Drinking before, during, and after training is just as important as drinking during the rest of the day. Aim for 16 ounces (2 cups) of water at about two hours before you run. Pair this with a snack or meal. About 15 minutes before a run, drink six to eight ounces of water.
Try drinking 16 oz. of water two to three hours before the start of any race. This gives your body time to process the extra fluids, meaning time for you to use the bathroom before the start. You may choose to sip some water up to the start, especially on a warm day.
Just like cramming for a test, binge (water) drinking the morning of a long run won't hydrate you properly. Aim to drink about 2-3 mL perpound of body weight at least 4 hours before your run.
Hydration is particularly important for runners. “Running and sweating increases the amount of fluid we need,” says Skolnik.
It is said that we should not drink water just after strenuous exercise. Is there any scientific basis to it? There is no scientific contemplation behind this belief that we should not drink water just after strenuous exercise. During a workout, the body loses a lot of fluids through sweating and leads to dehydration.
Drinking fluids and sweating
In fact, it is excessive water which can cause problems with metabolites in the blood leading to lack of concentration and irritability as well as excessive sweating.
Just like you want to go into the race with proper energy stores from nutrition in the days before an event, it is best to be well hydrated right from the morning of the race. The only way to do this is to drink extra water the day before the race.
A proper hydration schedule should involve consuming about 16 ounces of water every 3-4 hours over the course of 48-72 hours before a race. This should happen until about an hour before the race.
Only water is necessary during 5k and 10k events. Drink 4oz every 15 minutes.
If you are planning to go for a long run, avoid the consumption of energy drinks. Most energy drinks are loaded with sugars and some even contain caffeine, which can create an urgency to urinate. Excessive caffeine consumption also causes the heart rate to pump up and augments the runner's stress levels.
Shallow breathing and poor digestion due to eating or drinking too much before a race can cause stomach cramps. Dehydration, poor stretching and insufficient carbohydrate intake can cause severe muscle cramps in the legs and calves.
"Many people think dehydration causes muscle cramps and will drink pure water while exercising to prevent cramping," he said. "We found that people who solely drink plain water before and after exercise could in fact be making them more prone to cramps.
Chugging large quantities of water isn't hydrating you any more than if you sip it slowly. It can seem like you're being proactive by gulping down a large amount of water before beginning some extraneous exercise.
Hydrating for a marathon or half marathon actually requires focusing on your fluid intake well before the race ever begins. In fact, many experts recommend maintaining proper hydration for two days leading up to the race. This gives you your best chance of starting the race adequately hydrated.
A recent study in the journal Medicine and Science in Sports and Exercise found that taking electrolytes before your run can also enhance fluid retention, thereby improving rehydration.
Before Running
If it's warm and you want to hydrate, a sports drink like Energy Drink will provide carbohydrate and electrolytes before training. If it's been a hard day at work or home, caffeine gives you the extra boost needed to get out running when you don't feel like it.
If you are prone to stomach discomfort but need energy for your run it might be useful to have a lower fibre carb option before you run, a banana, rice cakes with jam or honey, 300ml Powerade, a slice of toast with vegemite.
Effects of alcohol on sports performance
Alcohol dehydrates you. This is because it is a diuretic, which means it makes your kidneys produce more urine. Therefore drinking too much alcohol can lead to dehydration. Exercising soon after drinking alcohol can make dehydration worse because you also sweat during exercise.