Maintaining an optimal level of hydration is essential for any form of exercise, especially since two thirds of the body is made up of water. Regardless of the weather being hot or cold, good hydration habits are essential for health, sustaining performance and the avoidance of injury.
Thirst or a dry mouth are the first indicators of when the body is lacking only one or two percent of its optimum level of water. That may sound insignificant, but consider that two percent is a 1.4kg fluid loss in a 70kg athlete. This level of water loss can be easily reached, with strenuous exercise in hot conditions leading to a loss of up to two litres per hour through sweat.
However the more benign symptoms of hydration can quickly escalate to fatigue, dizziness and headaches. By the time dehydration of the body reaches ten percent it can be life threatening, effecting heart rate, breathing, blood pressure and consciousness.
Hydration and sports performance
During exercise fluid is lost through sweat and needs to be replaced to maintain blood volume, assist in muscle contractions and regulate body temperature. As dehydration sets in there is a gradual decrease in mental and physical performance. For example the physical increases to body temperature and heart rate, will also increase the perception of how hard the exercise feels.
One way in which to ensure that hydration is maintained is to measure how much fluid is lost. Simple to do, it is a matter of weighing oneself at the start of exercise, making sure to empty the bladder first, then at the end of the exercise session, weighing once again. The change in weight reflects the total fluid loss. Also note that during post exercise recovery there is a tendency to lose even more fluids through sweat and urine. So it is best to replace 125% to 150% of the total fluid loss, and do this gradually over the next two to six hours. Obviously any fluid consumed during exercise must be taken into account along with what you are wearing, for example sweat laden clothing will skew the results.
The science of water absorption
Whatever the results, this fluid should be replaced during, and as soon as possible after, exercise.
Keep in mind though, that the amount of fluid you absorb is of more importance than the volume.
Water will work perfectly well for restoring fluid levels if the exercise is moderate and for less than an hour. It is has the benefits of being the cheapest, simplest and most accessible option for hydration. A challenge to replace sweet drinks with water for a month is currently running to highlight these benefits.
For the times where sport is more intense and sustained, there will be a need to maximise the efficiency of the fluids consumed. This is achieved through sodium, glucose and other minerals by aiding the movement of water in the the intestine directly into the bloodstream.
Dehydration can reduce this rate of fluid absorption from the intestines and this is where electrolytes come into play, most commonly found in sports drinks.
Sports drinks role in hydration
The main electrolyte found in sports drinks, sodium, helps assist with fluid replacement and improves the desire to drink. Replacing electrolytes used during exercise, is essential for the contraction of muscles, in other words to prevent cramping. The other main ingredient glucose, provides carbohydrates that supply the muscle with easily accessible fuel during exercise.
Hydration is most effective when the sodium and glucose, or in simplified terms salt and sugar, are in the right proportions for the type, duration and level of exercise. These variables are mostly covered by three basic options for sports drinks: isotonic, hypotonic and hypertonic. Each of these contain various levels of fluid, electrolytes and carbohydrate that determine their use.
Isotonic is the most in balance with the body’s fluid, and as such quickly replaces fluids lost by sweating. It also supplies a boost of carbohydrates in the form of glucose, making it the choice for most athletes, for example middle and long distance runners and those participating in team sports.
Hypotonic also replaces fluids lost through sweating yet has a lower level of carbohydrates, making it ideal for jockeys and gymnasts. Hypertonic on the other hand is high in carbohydrates, normally used after exercise to to top up muscle glycogen stores. It can also be taken during long distance events where the body has a higher energy need, but must be used in conjunction with isotonic drinks to replace fluids.
When exercising most people look towards sports drinks to replace glucose and electrolytes. Although the majority of drinks contain sugar as carbohydrates, and sodium as salt, they often contain potassium, calcium and magnesium which form the electrolyte composition of sweat.
One of the biggest concerns with sports drinks is the high level of sweetness, with some varieties havinga similar amount of sugar per 600 ml bottle to 300ml can of soft drink. There are some sports drinks on the market that contain no sugar or calories, but it has been argued that the ingredients that are used in their place to add flavour, cause more harm than the sugar.
So this would suggest that the best way to enjoy a healthy sports drink, is to make your own.
Matching sports drinks with a natural alternative
The simplest way in which to make a sports drink is a base of water, a natural form of glucose and an electrolyte, with sodium being the most easily sourced. Starting with equal amounts of tap water to fresh orange juice and a pinch of sea salt, this will tick the box for a basic isotonic sorts drink, that is, water, sugar and salt.
For a hypotonic drink, reduce the sugar and thus carbohydrates, by having a quarter serve of fresh orange juice with a three quarter serve of water. Alternatively for a hypertonic drink have more of a proportion of orange juice to water, as this will increase the carbohydrate level, important if exercising for more than an hour.
Honey, raw sugar or other juices such as lemon and apple, can also be used to increase sugar levels. Then other minerals can be introduced in the off the shelf variety, such as a teaspoon of calcium magnesium powder. Alternatively to stick the naturally packaged variety, nuts, such as cashews and almonds, are a fantastic source of calcium and magnesium. They also contain phosphate and potassium, to complete the main minerals that are used to provide sports drink electrolytes.
To compete with the visually appealing and flavoursome sports drinks on the market, adding in honey, mint, ginger can spice things up a bit. Also for an off the shelf, natural alternative, pure coconut juice is great as an isotonic drink as it contains an ideal amount of carbs and an impressive mix of minerals, that include sodium, potassium, phosphorus, calcium and magnesium.
Good habits of hydration
Depending on the sport pursued, the conditions in which they are undertaken and the physical makeup of the athlete, the challenged hydration poses are different for each individual. Some exercise has formal breaks, such as team sports, whilst the rest period in other activities are determined by the individual. Either way having access to fluids during exercise is best planned ahead, especially in the lead up to a game or event, to ensure proper hydration is optimised before commencing the activity.
To increase the absorption of water whilst exercising it is a good to have around a third of a litre of fluid before you begin. This may feel uncomfortable but the aim is to increase the flow of fluid from the stomach to the intestine. To keep this movement of fluid constant during exercise, take three to four sips of your chosen drink every ten minutes. Drinking more is better than less, as dehydration will reduce the rate of fluid absorption from the intestines. It doesn’t have to be all sports drink though, as many experts recommend having two serves of water for ever one serve of sports drink.
However, when caught out unexpectedly and feeling the first stages of dehydration, it is wise to stop exercise and try to drink two litres of water slowly over the next two to four hours. Avoiding any diuretics, such as coffee, tea or alcohol is also important.
Also note that drinks with a high concentration of sugar can have a diuretic effect, as the kidneys are designed to expel excess sugar out of the blood via urine. So sports drinks in this regard are best kept for when high intensity ‘stop-go’ and endurance sports are performed. When performing low intensity or short duration sport, water should suffice, with a healthy diet providing any minerals and sugars that the body needs.
One thing is for sure, that there is plenty to choose from when it comes to hydration options. Should making a decision be daunting, then simply asking a health professional or mentioning it at the next physiotherapy consultation, can provide some clarity based on your needs. Keeping a close eye on your favourite sports person may also provide some hydration tips, particularly helpful if you play that sport.
Now regardless of whether your chosen hydration beverage is half full or half empty, there is plenty of incentive to top it up.