Proper hydration is the key to sports and exercise success. How much to drink? What to drink ? When to drink? In this 2^nd part of the Sports Nutrition series, let Dr LOW WYE MUN tell you what science and practice has to offer you.

Athletes have a drinking problem. And those involved in endurance sports have the biggest challenge. No, I am not referring that kind of drinking but to the reason why companies world-wide are falling over themselves getting new sports drinks onto the shelves of your local stores. In order to help you make sense of the advertising and the confusing accounts of what to drink, let’s review some of the basics of hydration for sports people.

---

Reasons for sports people to hydrate properly

• When you exercise, your muscles produce heat and this raises your body temperature. The body’s systems can only work well in a very narrow temperature range, and so the body tries to shed this heat as efficiently as possible.
• One of the main means of losing heat is by sweating. This involves loss of water vapor and sweat through the skin. Sweat is made up of water (99%) and salts (also called electrolytes). The latter includes sodium (for you food label readers, this goes by its chemical symbol, Na), chloride, potassium, calcium, urea, and ammonia.
• Higher intensity exercise and hotter climates increase the amount of sweat produced. You can lose more than 1 liter of sweat per hour (some athletes have lost up to 2.5 L per hour in marathons), and this must be replaced. If your conditioning is not up to par or if you are not acclimatized to exercise in the heat, your sweat will contain relatively more salt – another replacement priority.
• Failure to adequately replace the lost sweat leads to a fall in physical performance (muscle strength, endurance, co-ordination) and an increased risk of developing heat exhaustion and heat stroke.

---

How much fluids should I drink when I exercise ?

In theory, you should drink enough to replace the amount of water and electrolytes that you lose in your sweat. As people sweat at different rates, it is not possible to state exactly how much you should drink. But here are some important guidelines that may help you determine this.

• It is important to hydrate before your training or competitions, but equal emphasis should be placed on drinking at the end of your exercise. This post-exercise drinking is very important for proper recovery of the body: you replace fluid that is lost, and depending on what you drink, you also start to replace energy stores (eg. the glycogen in your muscles) which prepares you for your next high-quality training or race.

• If your sport or activity lasts more than an hour, you should be drinking during the activity. This is something you should include as part of your training. In other words, you should drink while you train. This maintains the optimal state of your body during training, and helps you to be efficient in how you drink and knowing when to drink. It also helps you to try out different hydration fluids to find out what works best for you.

• As a rough guide to drinking in an endurance event, aim to drink about 300-500ml of cool fluid 20 minutes before the event starts. The body can empty about 1 L of water from the stomach to be absorbed in the small intestine in an hour. So drinking about 200-250ml every 10-15 minutes will allow you optimize your fluid absorption. So don’t miss those drink stations, and make sure your bike water bottles stay full.

• If you are waiting to feel thirsty before you start drinking, you are setting yourself up for a bad experience. This is because thirst is a body response to the level of water in the body systems, but the response is delayed. That means that by the time you are thirsty, you have already lost a significant amount of fluids.

---

FLUID FACTS & FANTASIES

• Cool fluids are absorbed the fastest by the body. This means about 10 deg C which is about the temperature of a glass of water with some ice cubes. Conversely, a warmer fluid will be absorbed more slowly and will slosh around in your stomach, which can be uncomfortable.

• Fluid trivia: one of the earliest sports drinks to hit the Singapore market was a Pocari product called SWEAT. While perhaps not a triumph of name branding (do you really want to drink a can of SWEAT ??), it certainly conveyed the right purpose: replacement of the sweat loss. You can still find this pomelo-tasting sports drink on the shelves of your favorite supermarket.

• Not all energy and fluid replacement drinks are the same. Check out the calories and electrolytes some local favorites give you (all the information is based on a standard 330ml can):

 

Name	Calories	Sodium	Potassium	Chloride	Calcium
100 Plus	89 kcal	69 mg	13 mg	36 mg	–
H20	83	66	13	36	3
Gatorade	69	151	51	–	–
Pocari Sweat	90	150	–	–	–
Sportade	83	139	116	–	–
Fierce	69	151	41	–	–

n.b. By comparison, the caloric levels (kcal) in other favorite non-sports drinks were: Milo 248 , Coke 139, Red Bull 149, Lucozade 241.

---

PITFALLS OF HYDRATION

• Yes, it is possible to drink TOO MUCH fluids. This is of special concern in endurance events where participants over-hydrate before and during the event. What happens then is that the body loses water and electrolytes, and too much water is drunk to replace this. The excessive water now dilutes the remaining electrolytes (especially sodium) in the blood, and a condition arises called hyponatremia. This can cause swelling of the brain and lead to symptoms similar to a heat disorder: headache, nausea, confusion, and convulsions. And like heat stroke, it can kill you.

• In an attempt to glug down all those essential electrolytes, some athletes have discovered the down-side of hydration (resulting in an upchuck..): fluids which are not diluted enough not only give a mouth-drying feeling, but can also cause stomach upsets too. Some complain of headaches. This is most distressing when the event still has some hours to run, and so the word to the wise is two-fold: experiment with your fluids during training, and if in doubt, dilute the fluids more rather than less.

• Endurance athletes all have their own favorite concoctions when it comes to their energy food. And this holds true too for their favorite fluid mix. A visit to a bicycle or triathlon race will yield a rainbow of colors – not in the race clothing, but in those sexy translucent water bottles. Experience once again shines her light of wisdom: fruit juices do not work for everyone. Juices made from oranges and apples may be refreshing after a period of exertion, but they are acidic and can irritate the stomach when imbibed over the course of a longer event. Again, test this before you adopt it.

There are other favorite endurance athlete drinks and food out there. From Power Gels and Bars to plain old bananas, they contain calories, electrolytes, and even some added ingredients all aiming to boost your sports performance. Like caffeine, which is touted as a performance enhancement substance – a legal one. Next month, we’ll explore this and other supplements that lay claim to helping you move faster, stronger, and for longer.