Hydration Information

POWERADE and the Science of Hydration

POWERADE Isotonic

POWERADE Isotonic sports drinks are designed to be in balance with your body's fluids to give you fast hydration and energy when you need it most. For those who train hard and push their body to the limits, sports drinks can be a key component to maintaining performance. Water alone isn't enough when you are playing intensive or endurance sport. Your body needs more.

What does "isotonic" mean?

The term isotonic means that the fluid has the same concentration of "solutes" (i.e. particles) as that found in your blood and cells. This means that when you ingest it, other fluid does not shift into your gut to dilute it; instead, the fluid in the isotonic drink just readily crosses over into the bloodstream.

 

What are the main ingredients in a sports drink such as POWERADE Isotonic?

Most sports drinks comprise three main ingredients, electrolytes, carbohydrates, and water.

Electrolytes = essential salts

POWERADE Isotonic contains two essential electrolytes - Sodium and Potassium. Your body loses these salts in sweat and it is important they are replaced. The electrolytes in POWERADE Isotonic work in two main ways:

  • They replace the electrolytes you lose when you sweat.
  • They help you to retain fluid so you stay hydrated, as well as maintaining your blood volume, sweat rate and muscle blood flow. Without electrolytes your urinary output increases (ie. water passes straight through) and you won't remain hydrated.

There is also evidence that consuming sodium-containing sport drinks, like POWERADE Isotonic, stops your thirst mechanism from being switched off prematurely1,2. Although we often look for drinks to "quench our thirst", you also want to use your thirst to tell you whether you still need to drink more.

Carbohydrates = Energy for Muscles.

Carbohydrate is the main fuel source for muscles when working at a moderate to high intensity (i.e. at jogging pace or faster), and late in prolonged endurance exercise3. It is also the preferred fuel source for the brain4. We have a limited capacity to store carbohydrate (glucose or glycogen) in our body, so those who exercise regularly will require additional supplies from their diet to maintain adequate stores. Studies have shown that providing carbohydrate during exercise results in better exercise performance in sessions of as little as one hour of very high intensity5,6; for sessions of intermittent high intensity exercise, such as football and rugby3,4,7 and for more prolonged (greater than 90 mins) endurance exercise such as long distance running and triathlons3,4,7.

  • POWERADE Isotonic provides additional carbohydrates (sucrose & maltodextrin) to provide the energy that muscles need when working out.
  • The amount of carbohydrate in POWERADE Isotonic is designed to be appropriate for the body to absorb in exercise.
  • Adding carbohydrate to a fluid has been shown to assist fluid absorption from the gut and intestine (provided the concentration of carbohydrate is not too high)8.
 

Why drink a sports drink, as opposed to water?

The two main perspectives which differentiate a sports drink from water alone are the additional supply of fuel (carbohydrates) and electrolytes with the hydration. Also several studies have provided evidence that people will drink more of a flavoured drink than an unflavoured one1,6. Hence, a refreshing, palatable drink such as POWERADE Isotonic will generally be consumed more readily, thereby further enhancing total fluid intake and reducing the risk of dehydration. POWERADE Isotonic comes in a great range of flavours, all of which make it easier for you to keep drinking the amount you need to stay hydrated. Check out the "POWERADE Isotonic Range" for more information.

References

  1. Wilk B., Bar-Or O. 1996. Effect of drink flavour and NaCl on voluntary drinking and hydration in boys exercising in heat. J. Appl. Physiol. 80: 1112-1117.
  2. Wemple R., Morocco T., Mack G. 1997. Influence of sodium replacement on fluid ingestion following exercise-induced dehydration. Int. J. Sport Nutr. 7: 104-116.
  3. Coyle E.F. 2004. Fluid and fuel intake during exercise. J. Sports Sci. 22: 39-55.
  4. Maughan R. 2006. Fluid and CHO intake during exercise. In: Burke LM and Deakin V. (Eds). Clinical Sports Nutrition, 3rd Edition. McGraw-Hill: Sydney. pp 385-415.
  5. Jeukendrup A., Brouns F., Wagenmakers A.J., Saris W.H. 1997. Carbohydrate-electrolyte feedings improve 1 h time trial cycling performance. Int. J. Sports Med. 18: 125-129.
  6. Below P., Mora-Rodriguez R., Gonzalez-Alonso J., Coyle E. 1995. Fluid and carbohydrate ingestion indpendently improve performance during 1 h of intense exercise. Med. Sci. Sports Exerc., 27: 200-210.
  7. Sawka M.N., Burke L.M., Eichner E.R., Maughan R.J., Montain S.J., Stachenfeld N.S. 2007. ACSM Position Stand - Exercise and Fluid Replacement. Med. Sci. Sports Exerc. 39: 377-30.
  8. Maughan R. 2006. Fluid and CHO intake during exercise. In: Burke LM and Deakin V. (Eds). Clinical Sports Nutrition, 3rd Edition. McGraw-Hill: Sydney. pp 385-415.

Being well hydrated

Benefits of being well hydrated

Starting exercise properly hydrated gives you the best chance of minimising dehydration as you train, play, or race hard. It can also help keep your blood volume at optimal levels, and allows you to sweat to remove heat effectively. Athletes that are well hydrated are also likely to have better concentration and skill learning ability. So there are many good reasons to use POWERADE Isotonic to keep you well hydrated!

What happens to your body when you are dehydrated?

The following are some examples of what could happen to your body when you are dehydrated:

  • Thicker blood: When you start to dehydrate, your blood volume decreases and starts to thicken and slow. This puts pressure on your heart, making it work harder to pump oxygen and glucose to your muscles.
  • Muscles fatigue: Your active muscles lose muscle strength and fatigue.
  • Mental fatigue: Reaction times, concentration and decision making ability decrease.
  • Overheating: As the cooling effect of sweating decreases due to less fluid in your body, your core temperature rises.

Signs and Symptoms of Dehydration

It's important to recognise the following signs of dehydration. Some of the symptoms include:

  • Increased thirst
  • Dry mouth
  • Light-headedness
  • Fatigue
  • Impaired mental focus
  • Low / Dark urine output
  • Dull headache
  • Increased heart rate

When you're thirsty, it's your body's way of saying you're already dehydrated. As little as 2% dehydration (that is, 1.4kg loss in a 70kg person) may lead to a noticeable decrease in performance. Dehydration results in increased body temperature, increased heart rate, increased ratings of effort, reduced physical performance, and reduced mental performance1. Hence, drinking during exercise can help minimise detrimental effects, especially during more prolonged and / or higher intensities of exercise. There is also now some evidence that drinking cool fluids actually helps keep your body temperature down when you're exercising in the heat as well2. Mild dehydration can affect physical and mental performance, while severe dehydration can be life-threatening. Dehydration can develop quickly under some conditions, such as extreme heat. To avoid dehydration and perform at your best, pay attention to your thirst and make sure you consume plenty of fluids during the day.

Using urine colour as an indicator of hydration

The colour of urine is the simplest indication of your level of hydration, and is usually accurate. If it's clear or lightly coloured you're generally fine (unless you've just had large volumes of water without a sports drink or salty food - hence not retaining any fluid consumed); if it's dark yellow you're dehydrated (or have consumed large amounts of vitamin B and/or C through a supplement).

How much should I drink?

Check out the Hydration Calculator to estimate rough fluid requirements for your exercise or sport.

Can I drink too much? - Avoiding hyponatraemia

Whilst remaining well hydrated is key to feeling great and performing at your best, you need to be careful not to drink too much, or over-hydrate. Over-hydrating can result in a rare but potentially fatal condition known as hyponatraemia, or low sodium levels in the blood. This occurs when more fluid is consumed than can be effectively cleared by the kidneys (which tend to reduce their function during exercise). The symptom of hyponatraemia can be similar to dehydration - headaches (due to swelling of the brain), disorientation, nausea and vomiting 1. Most reports of hyponatraemia have occurred in ultra-endurance running events (often greater than six to eight hours), with those most at risk being slower runners with plenty of opportunity to drink. Drinking a sports drink doesn't necessarily reduce the risk, although it may help to lower the risk if volumes consumed and sweat rates are matched. The main issue is to not drink so much that you gain weight during the event2,3, so aim to finish exercise at the same, or a slightly lower, body weight than that with which you started. Knowing your own personal sweat rates under different weather conditions is a great way to ensure the fluid volume you take in is close to what you need - not too much and not too little. See "How to Determine Your Personal Sweat Rate" for help with this.

References

  1. Montain SJ, Cheuvront SN, Sawka MN. 2006. Exericse-associated hyponatremia: quantitative analysis for understanding the aetiology. Br. J. Sports Med. 40: 98-106.
  2. Shirreffs SM, Casa DJ, Carter R. 2007. Fluid needs for training and competition in athletics. IAAF Consensus Conference, Nutrition in Athletics. (publication pending, J. Sports Sci.).
  3. Rehrer NJ. 2001. Fluid and electrolyte balance in ultra-endurance sport. Sports Med. 31: 701-715.

Hydration Under Different Environmental Conditions

The effect of dehydration on performance varies across different weather conditions, with dehydration during exercise in the heat provoking larger performance decrements than similar activity in cooler conditions due to the combined effects of heat and dehydration1. Similarly, different environmental conditions alter the risk and rate of you becoming dehydrated. Furthermore, there are many people who have to work under varying environmental conditions, such as miners and military personnel, where the impact of dehydration on work output can be substantial. Understanding the risks and being conscious of your hydration practices are important components of optimising performance at work and on the field.

Fluid intake in the heat

Both dehydration AND exercising in the heat have independent effects on heart rate, body temperature regulation, concentration and performance - in combination, the effects are additive2,3. The effects of dehydration tend to be progressive (i.e. the larger the dehydration, the greater the negative effect on performance). In extreme cases, prolonged exertion in the heat combined with dehydration can increase the risk of heat stroke and heat illness, and even acute kidney failure resulting from the breakdown of muscle contents3.

Knowing how your own body responds when exercising in the heat is very important and will provide a baseline. Commencing exercise well hydrated, and maintaining a fluid intake pattern which matches sweat losses as closely as tolerable (i.e. without causing gastrointestinal discomfort), are essential for minimising the degree of dehydration incurred during exercise in the heat. In the heat, consideration should also be made for active cooling strategies, such as ice towels, ice vests, and cool water sprays. Use the POWERADE Hydration Calculator to determine fluid required for your particular exercise or sport. For extreme conditions use your sweat rate to guide fluid intake (see "How To Determine Your Personal Sweat Rate")

Fluid intake in the cold

The risk of dehydration during exercise in cooler weather conditions can be as high as in hot conditions. Many sports are played indoors, and/or people train with more clothes on, so their actual sweat rates can be close to those in warmer conditions. In contrast, most people drink much less in cooler conditions. The net result of less fluid but similar sweat rate can lead to similar levels of dehydration being incurred in cooler climates to those in warmer conditions. For example, whilst the average sweat rate for footballers in summer training is higher than winter training (1.46 versus 1.13 L/hr), the fluid intake during training during winter was less than half that in summer (650 ml/hr in summer versus 280 ml/hr in winter), so the overall dehydration incurred was slightly higher (1.59% in summer, 1.62% in winter)3. However, evidence suggests that for the same level of dehydration, there is more impact on performance in hotter rather than cooler conditions 4.

So, the important message for those exercising in cool environments is to still pay attention to fluid intake as substantial dehydration can still occur. Individuals need to be aware of their sweat losses when exercising in the cold, and to drink according to their sweat rates.

Fluid intake at altitude

Many sports are undertaken at higher altitudes - such as winter sports, mountain climbing, and aerial sports. Athletes can also take advantage of training at higher altitudes to help boost their performance in critical events. At altitude, the air is thinner in terms of oxygen supply, but is also drier, resulting in more fluid being evaporated from the body passively (from the airways and the skin). This is the reason why people get dry throats and cracked lips in the first few days of being at altitude. There is evidence that fluid shifts around the body contribute to acute mountain sickness (altitude sickness) 5.

In addition to drier air, higher altitudes tend to be cooler, which as discussed earlier, reduces the drive to drink. Therefore, increasing the volume of fluid consumed to counteract the increased dehydration of altitude is important. The focus should be on maintaining urine output (pale in colour), as well as ensuring fluid lost during exercise is adequately compensated.

Fluid intake when travelling

Many forms of travel, such as airlines and air-conditioned buses, involve sitting in much drier air than that to which most of us are usually exposed. This "dry air" promotes greater fluid loss than being in humid air, mainly from the skin and airways via evaporation. Hence, although individuals are not exercising, fluid intake should be sustained at a consistent rate to ensure arriving well hydrated. The other benefit to sustaining hydration during travel is that it generally results in more toilet visits, which helps keep muscles and circulation moving as you walk around .

References:

  1. Murray B. 2007. Hydration and physical performance. J. Am. Coll. Nutr., 26: 542S-548S.
  2. Ganio MS, Casa DJ, Armstrong LE, Maresh CM. 2007. Evidence-based approach to lingering hydration questions. Clin. Sports Med. 26: 1-16.
  3. Sawka MN, Burke LM, Eichner ER, Maughan RJ, Montain SJ, Stachenfeld NS. 2007. Exercise and fluid replacement. Med. Sci. Sports Exerc. 39: 377-390.
  4. Gonzalez-Alonso J, Mora-Rodriguez R, Coyle EF. 2000. Stroke volume during exercise: interaction of environment and hydration. Am. J. Physiol. Heart Circ. Physiol., 278: H321-H330.
  5. Nerin MA, Palop J, Montano JA, Moorandeira JR, Vazquez M. 2006. Acute mountain sickness: influence of fluid intake. Wilderness Environ. Med., 17: 215-220.