Ergogenic aids

Sports drinks as a means

of hydration.

Word Count – 2460

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Introduction

The purpose of this study is to examine hydration methods and their effect on performance.

The theory behind nutritional aids is to supply more than the body naturally produces, for

example, Creatine. With more total muscle creatine readily available, the greater the net ATP

produced in the muscle during contraction and also the rate of PCr resynthesis during recovery

increases. (Balsom, Ekblom, Soderlund, Sjodin & Hultman, 1993; Balsom, Soderlund, Sjodin &

Ekblom, 1995; Birch, Noble & Greenhaff, 1994)

Many sports drinks claim to hydrate better than water and it is this that is interesting.

Water is one of life’s most essential nutrients. Being the most abundant component in the body at

60%, it helps to regulate temperature, lubricate joints, transport nutrients and pass waste. Water

is stored both intracellular (blood plasma) and extra cellular (GI tract) and transports electrolytes

(Na, K) and small ions to help regulate fluid balance and the distribution of water inside and

outside the cells. It is fluid balance in particular to exercise that is the limiting factor in terms of

performance. It is the concept of human homeostasis where the amount of fluid lost is equal to

the amount of fluid taken in. If not, this is by definition, dehydration. Fluid balance has many

limiting factors itself, conditions of subject, the amount of physical activity and the environmental

factors.

Mechanisms

The theory behind sports drinks, are that they aim to replace/maintain the electrolytes and water

lost during exercise. Which in turn increases performance or allows the athlete to maintain the

current level of intensity (Rivera-brown, Gutierez, Gutierrez, Frontera & Bar-Or, 1999). This study

also shows the total volume of flavoured water ingested, with 6% Carbohydrate and 18mmol/l

Na+, was higher than that of plain water. Suggesting that sports drinks seem to be more

palatable than water and therefore aid hydration status better.

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Many sports drinks contain different ions and claim to have different properties than others, but

realistically they all do the same thing. It has been found (table 1), that the basis of all sports

drinks are carbohydrates from simple to complex. They are essential for energy and for

maintaining and restoring blood glucose after exercise. The more carbohydrates a sports drink

can offer the more potential there is for them to reach the muscles for fuel as each has a different

absorption site and rate. Studies have shown that the inclusion of carbohydrates can increase the

work output and prolong exercise duration, (Tsintzas, Williams, Campbell & Gaitanos, 1993;

Coyle, Hagberg, Hurley, Martin, Ehami & Holloszy, 1983)

Different activities have different rates of carbohydrate utilization. For example a high intensity

cycling event showed that the rate of muscle glycogen use was unaffected by the ingestion of a

carbohydrate solution, (Coyle, Coggan, Hemmert & Ivy, 1986), whereas when a carbohydrate

solution was ingested during a long distance running event the rate of muscle glycogen use

decreased (Tsintzas, Williams, Boobis & Greenhaff, 1995). Also activities with high intensity,

short bouts, showed no depletion but increased performance (Below, Mora-Rodriquez, Gonzalez-

Alonso & Coyle, 1995). The type of carbohydrate and concentration is important, however studies

have shown no major difference between their effects (Coyle et al., 1986) however fructose has

been found to cause some intestinal distress (Murray, Paul, Seifert, Eddy & Halaby, 1989). Sports

drinks containing sodium are better for re-hydration, as sodium helps maintain fluid balance and

promotes the uptake of water into the intestines, (American College of Sports Medicine, (2005).

Selecting and effectively using sports drinks, carbohydrate gels and energy bars. Retrieved

August 3rd, 2011, from

http://acsm.org/AM/Template.cfm?Section=Brochures2&Template=/CM/ContentDisplay.cfm&Con

tentID=12036). It also decreases dehydration factors such as urine production through a negative

feedback loop. When high levels of Na+ are detected in the blood stream, the brain releases an

anti-diuretic hormone to the kidneys to reduce the production of urine. This process also retains

the volume of water in the body by using it to dilute the high Na+ concentration. (Control of urine

volume. Retrieved August 12th ,2011, from http://www.nsbri.org/humanphysspace/focus4/ep-

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urinecontrol.html)

Table 1

Different sports drinks readily available and contents.

Lucozade Sport - LITE Carbohydrate – 2g (of which sugars – 1g)Nlacln – 0.61mgVitamin B6 – 0.07mgVitamin B12 – 0.03gPantothenic Acid – 0.21mgCalcium – 37mg

Powerade Xion4 Sodium – 0.05gCarbohydrates – 3.9g (of which sugars – 3.9g)Potassium – 12.5mgCalcium – 1.3mgMagnesium – 0.6mg

Gatorade Perform Series 02 Low Calorie Sodium – 110mgPotassium – 30mgCarbohydrates – 5g (of which sugars - 5g)

Gatorade Perform PRO Series 2 Sodium – 200mgPotassium – 90mgCarbohydrates – 14g (of which sugars – 14g)Calcium – 6mgMagnesium – 3mg

Gatorade Perform Natural Series 2 Sodium – 110mgPotassium – 30mgCarbohydrates – 5g (of which sugars – 5g, Sugar alcohol – 4g)

Loss of these ions and minerals speeds up the onset of fatigue, which decreases performance.

(Montain & Coyle, 1992; Coyle et al., 1983; Coggan & Coyle, 1989.)

Sports drinks are used before, during and after exercise. These days most companies have

multiple drinks for each, some, e.g. Gatorade, have an entire series. These are founded on the

basis that elite athletes are more susceptible to a greater loss of electrolytes and carbohydrates

through higher intensity and extended duration.

The aim of consuming sports drinks is to prevent dehydration/re-hydrate (defined as >2% loss in

body weight) (Hargreaves, 1996; Burke, 1996). And by keep the body functioning efficiently

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during and after exercise. They also aim to replace fluid lost. They speed up the rate at which

ingested fluid leaves the stomach and is absorbed, and also they increase the amount of total

fluid absorbed.

Review

- Pre Exercise

Athletes should begin exercise in a well-hydrated state. Avoiding diuretic drinks such as tea,

coffee and alcohol, is important as these stimulate greater/more-often urinary responses.

Recommendations are that they consume approx 5-7ml/kg BW roughly four hours before

exercise and this should be paired with a meal.

Studies have shown that, athletes that are in a better state of hydration, before exercise occurs,

perform better than dehydrated athletes.

Burge, Carey and Payne (1993) tested 8 international male rowers in a state of dehydration (pre

exercise) and re-hydration (during) and found that Rowing trial time increased significantly from

7.02 +/-0.17 min for the dehydration to 7.38 +/- 0.21 min for the re-hydration (P < 0.05).

Other studies also showed similar results, (Armstrong, Costill and Fink, 2003; Below et al., 1995;

Judelson et al., 2007; Pitts, Johnson and Consolazio, 1944). Athletes that super hydrate can

increase their blood plasma volume; decrease core body temperature and heart rate, which

increase performance. (Kristal-Boneh, Glusman, Shitrit, Chaemovitz & Cassuto, 1995)

- Performance

During exercise a high rate of metabolic heat production occurs and body temperature rises. As a

result the body begins to sweat to promote evaporative heat loss. The ingestion of fluids is vital to

replace fluid balance although the rate at which this is ingested does not match the rate of

perspiration and there is usually some fluid deficit as a result of exercise; also maintenance of

good fluid intake is important to avoid heat exhaustion. (Lyle et al., 1994). The best method to aid

heat exhaustion to is drink plenty of fluids, (Lyle et al., 1994; Walsh, Noakes Hawley & Dennis,

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1994) It is difficult to avoid, as thirst is not a good indicator of the body’s requirement for fluid

(Hubbard, et al., 1984; Engell, et al., 1987). If an athlete does not consume enough fluid

correlated to rate at which perspiration occurs, there is a risk of dehydration and in severe cases

serious health effects. Athletes are advised to consume enough fluid to avoid substantial fluid

loss; this in turn maintains plasma volume, electrolytes, prevents abnormal increases in heart rate

and core body temperature and most importantly provides fuel. There is no single volume as it

depends on many factors, such as exercise intensity and environmental factors, but athletes

should consume based on sweat loss and start early and consume frequently. In relation to

sports drinks, consuming too much to fast can cause GI distress, alternatively, too little can have

no affect. Recommendations for carbohydrate intake are, 1g per min in a solution containing

between 6-8% carbohydrate at a volume intake of 0.6-1.2l/h (Coggan & Coyle, 1987)

- Recovery

It is vital to replace lost electrolytes, water and glycogen stores after exercise, although many

athletes never replace or consume fluids at a rate of more than 70% of perspiration, most are

lower (Borad, Burke, Gox, Heeley & Riley, 1996). Sports drinks contain the salts that the body

uses during exercise for performance. The depletion of these causes dehydration. Most athletes

prefer sports drinks, as they are more palatable than water. Generally water, seemingly tasteless,

losses its appeal after a while and quenches thirst. Sports drinks do not tend to quench thirst and

combined with flavours are more appealing, causing athletes to consume more. Evidence has

shown sports drinks to be more beneficial than plain water (Gonzalez-Alonso, Heaps & Coyle,

1992). It must be considered that if another bout of exercise is scheduled the same day or shortly

after the first, it is of higher importance to correctly replace fluids

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Table 2

Sweat rates in different athletes competing in different sports

Sport Environment (C) Sweat Loss (ml/h)Marathon 6-24 540-1520Football 10

2510001200

Basketball (m) (f)

20-2520-25

1600900

Rowing 1030

11651980

(Maughan & Shirreffs, 2004)

Table 2 shows textbook data for sweat loss across different sports, although this data is often not

useful as the individual fitness levels, training intensities etc for the athletes are unknown. But as

a mean it shows a large fluid loss in just one hour. This data also does not factor in water loss

from other causes such as respiration and urination.

As a gold standard, it is recommended that athletes replace 150% of fluid lost during exercise.

This can be calculated by the difference in body weight post exercise.

Discomforts

Sports drinks high in CHO and high intensity exercise can cause a decrease in the rate of gastric

emptying, which can cause discomfort to an athlete, as a large amount of fluid sits in the

stomach. (Vist and Maughan, 1995)

Although not sports related, the high sugar content of sports drinks has been known to cause

dental problems. Milosevic, A. (1997), found that all sports drinks available had erosive potential

but not that where directly detrimental to oral hygiene if consumed correctly.

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- Hypohydration

When the body looses too much fluid (>2% of BW) through urination, sweating etc, there can be

physiological consequences, which can cause discomfort to an athlete. Hypohydration can cause

an intolerance to heat due to greater heat storage, as the body can not cool down with sweat

(Pitts et al., 1994).

If fluid loss becomes greater than 5%, there are more severe effects including, Increased heart

rate, further increase in core body temperature and nausea.

In cases of fluid loss greater than 10%, medical help should be sought immediately, as this level

is often fatal. Effects include, Vomiting, breathing difficultly, seizures and unconsciousness.

(Signs and symptoms of dehydration, Retrieved March 10, 2011, from

www.sympotomsofdehydration.com)

Effectiveness

- Carbohydrates

Carbohydrates need replacing to restore blood glucose concentration and maintain carbohydrate

oxidation in the later stages of prolonged exercise.

Maltodextrin, a complex carbohydrate, has become vastly popular in sports drinks recently.

Studies have shown that it has no advantage compared to glucose or sucrose but its preferred by

athletes and sports scientists as it is more palatable in concentrations containing >10%

carbohydrate. (Brook, Davies and Green ,1975; Massicotte, Peronnet, Brisson, Bakkouch and

Hillaire-Marcel, 1989; Murray, Paul, Siefert, Eddy and Halaby, 1989; Owen, Kregel, Wall and

Gisolfi, 1986.)

Gonzalez-Alonso, Heaps and Coyle (1992) found that dilute CHO solution was more effective for

post exercise re-hydration than water.

If exercising in a hot environment it is wise to avoid high CHO concentrated drinks as they

decrease the rate of gastric emptying. Exercise of moderate to high intensity requires an increase

in the need to replace CHO. Although there are exceptions, for example, a marathon runner may

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run most of their race, metabolising fats and not there CHO stores, whereas a football player,

sometimes performing at high intensities, over 90 minutes plus extra time, will use up more CHO

stores. During moderate to high intensity exercise it is important to balance which need is greater,

fluid replacement or CHO replacement.

- Electrolytes

During intense, prolonged exercise, large amounts of salt can be lost through sweat, (Costill,

1977) and these amounts differ greatly between individuals.

Though salt loss does not effect performance directly, it has been found that sodium chloride

replacement during exercise can increase voluntary fluid intake, protect plasma volume (Below et

al., 1995) and decrease urine production (Vrijens & Rehrer, 1999), all dehydration factors.

A study by Costill and Sparks (1973) highlighted that the ingestion of a glucose solution after

severe dehydration resulted in a greater restoration of blood plasma volume, in comparison to

water.

Practical Recommendations

There are no specific supplementation recommendations for hydration as everyone differs

greatly. The basic guidelines have been outlined. It is the responsibility of the athlete and/or

coach to tailor these to the athletes’ specific sport and daily exercise regime. It is also important

that it is tailored to individual sweat rates and the climate.

The importance of hydration increases as the intensity of exercise increases. During training

periods there will be less re-hydrating occurring than in competition, that is, assuming that training

in less intense.

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Conclusions and Further Directions

In conclusion it has been found that sports drinks play a vital role in hydration and re-hydration of

an individual. These drinks contain water, Carbohydrates and Electrolytes that desperately need

replacing after exercise to ensure the human body remains in a state of hydration. The failure to

do this can result, in extreme cases, death.

It has been found that depleted electrolytes have no detrimental effect on performance but an

increase can aid voluntary fluid intake and the replacement of Carbohydrates lost are vital for

blood glucose concentration. Sodium supplimentation offsets urine production and sports drinks

containing multiple simple and complex carbohydrates have the ability to re-hydrate better than

plain water.

Every study stressed the need that recommended dosages/intakes should be made specific to

the athlete/event/environment.

The original focus of this review was to compare sports drinks with water in an attempt to support

or disprove what many sports drinks companies are stating these days; Hydrates better than

water.

A lack of research specific to this caused the review to focus on the effectiveness of sports drinks

alone. Further research needs to be aimed at these allegations made by these companies, not

only for science, but also for athletes.

It has to be noted that there are thousands of athletes competing all over the world that are not at

professional level and cannot afford nutritionists.

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