Hydration during exercise

What and when athletes drink depends upon exercise duration and intensity

By Elizabeth Quinn (from Sports Medicine)

Water is the most essential ingredient to a healthy life. Water has many important functions in the body including:

* Transportation of nutrients / elimination of waste products.
* Lubricating joints and tissues.
* Temperature regulation through sweating.
* Facilitating digestion.

Importance of Water During Exercise
Proper hydration is especially important during exercise. Adequate fluid intake for athletes is essential to comfort, performance and safety. The longer and more intensely you exercise, the more important it is to drink the right kind of fluids.

Dehydration
Athletes need to stay hydrated for optimal performance. Studies have found that a loss of two or more percent of one's body weight due to sweating is linked to a drop in blood volume. When this occurs, the heart works harder to move blood through the bloodstream. This can also cause muscle cramps, dizziness and fatigue and even heat illness including:

* Heat Exhaustion
* Heat Stroke

Causes of Dehydration

* Inadequate fluid intake
* Excessive sweating
* Failure to replace fluid losses during and after exercise
* Exercising in dry, hot weather
* Drinking only when thirsty

Hyponatremia - Water Intoxication
Although rare, recreational exercisers are also at risk of drinking too much water and suffering from hyponatremia or water intoxication. Clearly, drinking the right amount of the right fluids is critical for performance and safety while exercising.

Adequate Fluid Intake for for Athletes
Because there is wide variability in sweat rates, losses and hydration levels of individuals, it is nearly impossible to provide specific recommendations or guidelines about the type or amount of fluids athletes should consume.

Finding the right amount of fluid to drink depends upon a variety of individual factors including the length and intensity of exercise and other individual differences. There are, however, two simple methods of estimating adequate hydration:

1. Monitoring urine volume output and color. A large amount of light colored, diluted urine probably means you are hydrated; dark colored, concentrated urine probably means you are dehydrated.
2. Weighing yourself before and after exercise. Any weight lost is likely from fluid, so try to drink enough to replenish those losses. Any weight gain could mean you are drinking more than you need.

Things that Affect Fluid Loss in Athletes

* High altitude. Exercising at altitude increases your fluid losses and therefore increases you fluid needs.
* Temperature. Exercising in the heat increases you fluid losses through sweating and exercise in the cold can impair you ability to recognize fluid losses and increase fluid lost through respiration. In both cases it is important to hydrate.
* Sweating. Some athletes sweat more than others. If you sweat a lot you are at greater risk for dehydration. Again, weigh yourself before and after exercise to judge sweat loss.
* Exercise Duration and Intensity. Exercising for hours (endurance sports) means you need to drink more and more frequently to avoid dehydration.

To find the correct balance of fluids for exercise, the American College Of Sports Medicine suggests that "individuals should develop customized fluid replacement programs that prevent excessive (greater than 2 percent body weight reductions from baseline body weight) dehydration. The routine measurement of pre- and post-exercise body weights is useful for determining sweat rates and customized fluid replacement programs. Consumption of beverages containing electrolytes and carbohydrates can help sustain fluid-electrolyte balance and exercise performance."

According to the Institute of Medicine the need for carbohydrate and electrolytes replacement during exercise depends on exercise intensity, duration, weather and individual differences in sweat rates. [They write, "fluid replacement beverages might contain ~20–30 meqILj1 sodium (chloride as the anion), ~2–5 meqILj1 potassium and ~5–10% carbohydrate."] Sodium and potassium are to help replace sweat electrolyte losses, and sodium also helps to stimulate thirst. Carbohydrate provides energy for exercise over 60-90 minutes. This can also be provided through energy gels, bars, and other foods.

What about Sports Drinks?
Sports drinks can be helpful to athletes who are exercising at a high intensity for 60 minutes or more. Fluids supplying 60 to 100 calories per 8 ounces helps to supply the needed calories required for continuous performance. It's really not necessary to replace losses of sodium, potassium and other electrolytes during exercise since you're unlikely to deplete your body's stores of these minerals during normal training. If, however, you find yourself exercising in extreme conditions over 3 or 5 hours (a marathon, Ironman or ultramarathon, for example) you may likely want to add a complex sports drink with electrolytes.

General Guidelines for Fluid Needs During Exercise
While specific fluid recommendations aren't possible due to individual variability, most athletes can use the following guidelines as a starting point, and modify their fluid needs accordingly.

Hydration Before Exercise

* Drink about 15-20 fl oz, 2-3 hours before exercise
* Drink 8-10 fl oz 10-15 min before exercise

Hydration During Exercise

* Drink 8-10 fl oz every 10-15 min during exercise
* If exercising longer than 90 minutes, drink 8-10 fl oz of a sports drink (with no more than 8 percent carbohydrate) every 15 - 30 minutes. RECOMMEND THE REV 3 ENERGY DRINK

Hydration After Exercise

* Weigh yourself before and after exercise and replace fluid losses.
* Drink 20-24 fl oz water for every 1 lb lost.
* Consume a 4:1 ratio of carbohydrate to protein within the 2 hours after exercise to replenish glycogen stores.

Tips for athletes

Sports Nutrition - How Foods Fuel Exercise?

Elizabeth Quinn (Feb 2008)

How the body converts food to fuel relies upon several different energy pathways. Having a basic understanding of these systems can help athletes train and eat efficiently for improved sports performance.

Sports nutrition is built upon an understanding of how nutrients such as carbohydrate, fat, and protein contribute to the fuel supply needed by the body to perform exercise. These nutrients get converted to energy in the form of adenosine triphosphate or ATP. It is from the energy released by the breakdown of ATP that allows muscle cells to contract. However, each nutrient has unique properties that determine how it gets converted to ATP.

Carbohydrate is the main nutrient that fuels exercise of a moderate to high intensity, while fat can fuel low intensity exercise for long periods of time. Proteins are generally used to maintain and repair body tissues, and are not normally used to power muscle activity.

Energy Pathways
Because the body can not easily store ATP (and what is stored gets used up within a few seconds), it is necessary to continually create ATP during exercise. In general, the two major ways the body converts nutrients to energy are:

* Aerobic metabolism (with oxygen)
* Anaerobic metabolism (without oxygen)

These two pathways can be further divided. Most often it's a combination of energy systems that supply the fuel needed for exercise, with the intensity and duration of the exercise determining which method gets used when.

ATP-CP Anaerobic Energy Pathway
The ATP-CP energy pathway (sometimes called the phosphate system) supplies about 10 seconds worth of energy and is used for short bursts of exercise such as a 100 meter sprint. This pathway doesn't require any oxygen to create ATP. It first uses up any ATP stored in the muscle (about 2-3 seconds worth) and then it uses creatine phosphate (CP) to resynthesize ATP until the CP runs out (another 6-8 seconds). After the ATP and CP are used the body will move on to either aerobic or anaerobic metabolism (glycolysis) to continue to create ATP to fuel exercise.

Anaerobic Metabolism - Glycolysis
The anaerobic energy pathway, or glycolysis, creates ATP exclusively from carbohydrates, with lactic acid being a by-product. Anaerobic glycolysis provides energy by the (partial) breakdown of glucose without the need for oxygen. Anaerobic metabolism produces energy for short, high-intensity bursts of activity lasting no more than several minutes before the lactic acid build-up reaches a threshold known as the lactate threshold and muscle pain, burning and fatigue make it difficult to maintain such intensity.

Aerobic Metabolism
Aerobic metabolism fuels most of the energy needed for long duration activity. It uses oxygen to convert nutrients (carbohydrates, fats, and protein) to ATP. This system is a bit slower than the anaerobic systems because it relies on the circulatory system to transport oxygen to the working muscles before it creates ATP. Aerobic metabolism is used primarily during endurance exercise, which is generally less intense and can continue for long periods of time.

During exercise an athlete will move through these metabolic pathways. As exercise begins, ATP is produced via anaerobic metabolism. With an increase in breathing and heart rate, there is more oxygen available and aerobic metabolism begins and continues until the lactate threshold is reached. If this level is surpassed, the body can not deliver oxygen quickly enough to generate ATP and anaerobic metabolism kicks in again. Since this system is short-lived and lactic acid levels rise, the intensity can not be sustained and the athlete will need to decrease intensity to remove lactic acid build-up.

Fueling the Energy Systems
Nutrients get converted to ATP based upon the intensity and duration of activity, with carbohydrate as the main nutrient fueling exercise of a moderate to high intensity, and fat providing energy during exercise that occurs at a lower intensity. Fat is a great fuel for endurance events, but it is simply not adequate for high intensity exercise such as sprints or intervals. If exercising at a low intensity (or below 50 percent of max heart rate), you have enough stored fat to fuel activity for hours or even days as long as there is sufficient oxygen to allow fat metabolism to occur.

As exercise intensity increases, carbohydrate metabolism takes over. It is more efficient than fat metabolism, but has limited energy stores. This stored carbohydrate (glycogen) can fuel about 2 hours of moderate to high level exercise. After that, glycogen depletion occurs (stored carbohydrates are used up) and if that fuel isn't replaced athletes may hit the wall or "bonk." An athlete can continue moderate to high intensity exercise for longer simply replenishing carbohydrate stores during exercise. This is why it is critical to eat easily digestible carbohydrates during moderate exercise that lasts more than a few hours. If you don't take in enough carbohydrates, you will be forced to reduce your intensity and tap back into fat metabolism to fuel activity.

As exercise intensity increases, carbohydrate metabolism efficiency drops off dramatically and anaerobic metabolism takes over. This is because your body can not take in and distribute oxygen quickly enough to use either fat or carbohydrate metabolism easily. In fact, carbohydrates can produce nearly 20 times more energy (in the form of ATP) per gram when metabolized in the presence of adequate oxygen than when generated in the oxygen-starved, anaerobic environment that occurs during intense efforts (sprinting).

With appropriate training these energy systems adapt and become more efficient and allow greater exercise duration at higher intensity.

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Nutrition for the Serious athlete

Nutrition for the Serious or Professional Athlete

This newsletter article focuses on the professional or serious athlete. It really does not matter which sport the athlete is involved in, but instead, it is critical to understand the importance of nutritional support that is required to protect the health of the athlete and enhance his or her performance. The athlete is always trying everything possible to enhance their performance.

Providing the proper macronutrients and micronutrients is not only a critical aspect of protecting one’s health but also enhancing one’s athletic performance. Even though athletes are usually very well informed about nutrition and supplementation, they are frequently confused because there is so much conflicting information that is being promoted to the athlete. This month’s newsletter will shine a light on this subject from a medical standpoint, and hopefully give the reader a much better understanding of what is necessary to achieve both goals of optimal performance and optimal health.

Dr. Kenneth Cooper—the “King of Aerobics”

I have always been a fan of Dr. Kenneth Cooper who first coined the term “aerobics” in the early 1970’s. He literally began the exercise craze that has swept the US and western world. Initially, Dr. Cooper recommended the equivalent of 15 miles of aerobic activity every week as the ideal amount of exercise an individual needed to receive the optimal health benefits of exercise. Whether it was 15 miles of walking or running really did not matter. The individual could even choose to swim, play racquetball or tennis, or ride a bike, as long as the aerobic output was equivalent to running or walking 15 miles per week. He felt that any amount of exercise above this recommendation was simply frosting on the cake and “Super-Exercisers” and professional athletes were looked upon as the healthiest people in the world.

In 1994, Dr. Cooper wrote a book called The Antioxidant Revolution [Thomas Nelson]. The main reason that he wrote this book was to caution everyone that over exercising could actually be dangerous to their health. When an individual has a mild to moderate workout, the number of “free radicals” they produce goes up only a little. However, when they have a hard workout, the number of free radicals goes up exponentially, or in other words, off the chart. If these excessive free radicals are not quickly neutralized by an antioxidant, they go on to create more volatile free radicals, damage the vessel wall, cell wall, DNA of the nucleus, proteins, and fats. Exposure to these excessive free radicals can damage your immune system and lead to diseases like heart disease, strokes, cancer, Alzheimer’s dementia, Parkinson’s disease, arthritis, and the list goes on and on. Dr. Cooper noted in his book that he was seeing “Super-Exercisers” coming into his Aerobic Center who were dying prematurely of heart disease, cancer, strokes, and a host of other degenerative diseases. These were individuals who were only 45 to 55 years of age. This is what led him to write this book in the first place. He wanted to caution the professional or serious athlete that if they were going to continue aggressive workouts, they needed to be taking high levels of antioxidants. This can help prevent the oxidative stress by neutralizing these excessive free radicals produced by this over exercise.

Nutritional Supplementation

I personally believe that all of my patients need what I refer to as Cellular Nutrition. It is important that this cellular nutrition includes a complete and balanced antioxidant and mineral tablet along with a calcium/magnesium tablet, and essential fats (flax seed or fish oil capsule). However, anyone who must handle excessive free radicals, whether it is the result of an underlying disease or excessive exercise, needs to be adding optimizers to the regime. I have taught my patients and athletes for years that balance is the key. You need to have enough antioxidants on board to handle the number of free radicals you produce. If this is accomplished, you don’t develop this oxidative stress that can lead to these serious health problems. The serious athlete needs to be adding potent optimizers to their cellular nutrition each and every day that they have a hard workout or are competing. This can easily be accomplished by adding an additional antioxidant tablet along with some additional grape seed extract (90 to 180 mg) and CoQ10 (60 mg gel-form). This cellular nutrition along with these optimizers will optimize your antioxidant defense system, repair system, and immune system. Your recovery from your hard workouts will be much faster, and your overall performance will be enhanced. Since your immune system is also being optimized, you will find yourself much more resistant to infections and illness. Clinical studies with marathon runners have shown that about one-third of these individuals experience a major viral illness two weeks prior to a major competition and another third will experience a major viral illness two weeks following their competition. How sad it is for athletes who train so hard and so diligently to have to withdraw or have a sub-par performance because they became ill.

Macronutrition

Athletes tend to be the world’s best or worst eaters. I have heard so many serious athletes tell me in my office that one of the reasons they work out so hard is so that they can eat anything they want. Well, there is no doubt that well-trained athletes have a greater margin for eating whatever they would like without suffering near the consequences of normal individuals. However, can you imagine how well athletes could perform if they not only were in excellent condition, but were also providing their body with optimal nutrition? Especially athletes who have to perform for great lengths of time, like crosscountry runners, marathon runners, track and field performers, golfers, soccer players, football players, or basketball players. Any time you must be at your peak both mentally and physically for greater than one to two hours, how you take in your fats, proteins, and carbohydrates is very critical to your performance. For years, athletes have been told that they need to “carbohydrate load” prior to any competition in order to optimize their glycogen stores (source of quick energy). However, over 85 to 90% of the carbohydrates most of them were consuming were either highly-processed or high-glycemic. This leads to a roller-coaster ride for your blood sugars, which ultimately causes you to fall into this low-blood sugar range or hypoglycemia. You must realize that our brain thinks on blood sugar.

In order to remain focused and have the ability to concentrate, your blood sugars need to be stable. However, when your blood sugars are vacillating and dropping into this hypoglycemic or low blood sugar range, you can become weak and easily lose your focus. This also causes the release of our stress hormones that are needed to get this blood sugar back up into a normal range. However, it can also cause this vicious cycle of roller-coaster blood sugars to continue. What is sad is the fact that you can easily maximize your glycogen stores by simply eating the good lowglycemic carbohydrates. This will also stabilize your blood sugars and allow you to be mentally alert for prolonged periods of time during your workouts or competition.

Many athletes, especially power-athletes, feel they must be consuming high quantities of protein. This again is a fallacy. Your body needs protein, but it also needs fats and carbohydrates. If you are going to have any chance of optimizing your athletic performance, you need to be consuming good proteins, good fats, and good carbohydrates. The protein is critical for helping to repair muscle; however, good fats are needed to provide the hormonal production your body needs along with producing the body’s natural anti-inflammatories. Good carbohydrates provide the body’s preferred fuel source—glucose, along with all the important antioxidants, minerals, and vitamins these foods contain.

In my book, Healthy for Life, I discuss this problem in detail. I also give very specific guidelines regarding good fats, good proteins, and good carbohydrates. Any serious or professional athlete is going to be able to optimize their performance significantly by following these basic guidelines. You can order this book on my web site. Remember, you never should go hungry; however, when you do become hungry you should eat good proteins, good fats, and good carbohydrates. This way you will be providing your body with the nutrients it requires for optimal function.

Hydration

When I ran in high school and college track, it was absolutely forbidden to drink any water during our workouts. It was as if you were a pansy if you needed to drink water. How ironic it is to learn that when we lose even 1% of our hydration, our strength can decrease up to 15%. Fortunately, athletes in all sports are encouraged to drink water during workouts and competition. It is essential to remain well-hydrated for peak performance. However, I must caution you, what the body needs is water not sugar. Sports drinks are the worse thing that you could drink during competition, because although it provides water and some electrolytes, it also is loaded with highglycemic sugars. When you are working out or competing you may note a boost to your energy for a short 15 to 20 minutes; however, within a very short time your blood sugar will come crashing down along with you. Please, just drink water, or at the most drink water with some electrolytes, but nothing with sugar.

Rest—the Over-Training Syndrome

Finally, I want to discuss the principle of rest. The body actually becomes stronger during rest. Any muscle that has been broken down through training needs time to repair and heal itself. This simply takes time. If you are continually breaking down your muscles in an attempt to “get in shape,” your body will eventually collapse—the Over-Training Syndrome. Rest is not only critical but essential for the peak performance of the athlete. Your body needs at least 2 days of complete rest during the week. For weightlifters, you should not work a muscle to exhaustion without allowing that particular muscle or muscle group to rest for at least 4 days or ideally for 1 week following that workout. Now I realize that during your competitive season, it is difficult to get 2 days of complete rest—especially for team sports. However, most coaches now realize that rest along with light workouts is essential for optimal performance. If your muscles are becoming weaker instead of stronger, if you are not recovering as quickly from your workout, if you just do not feel well, consider the fact that you may be developing the “over-training syndrome.”

Increasing your antioxidant supplements will help; however, rest is critical. The sooner you recognize this problem, the sooner you can recover from its horrible consequences.

Conclusion

Hopefully, this will give you some guidelines for anyone who is a serious or professional athlete. This is also great information for anyone who is just trying to develop a modest, consistent exercise program. Exercise is critical for optimal health. The serious athlete along with the professional athlete needs to take extra precautions in order to optimize their performance and at the same time protect their health.