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Power of Protein

August 22, 2009 
Filed under Diet And Nutrition, Triathlon

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Jennifer Hutchison asks how much protein a triathlete really needs.

nutrition Power of ProteinHow much protein does a triathlete need? Is protein in a sports drink really necessary?

These two questions can spark a firestorm of debate amongst sports nutrition professionals, nutrition savvy athletes and sport nutrition manufacturers that promote products packed with a protein punch. This month I will discuss the third macronutrient that provides balance and protection in an athlete’s diet, protein.

Protein Basics
Dietary protein, like carbohydrate and fat, performs a very important job in an athlete’s diet. Protein’s primary role in the body is to support growth, maintenance and repair of muscle and other body tissues, while also being a backbone for many hormones and enzymes and supporting a healthy immune system. An athlete’s overall health and performance can be closely tied to protein balance. Protein intake that is insufficient can place the athlete at risk for illness and or injury.

Body proteins are constantly being broken down and resynthesized on a daily basis both at rest and during training. Protein, although not a preferred fuel source, can be used to sustain physical activity. Gluconeogenesis is the body process that breaks down protein (think muscle) and converts it to carbohydrate (glucose) to be used as fuel.

Dietary protein’s main purpose should be for the repair and recovery of damage muscle and cells caused by training and racing as opposed to being used as a fuel source. In order to do this athletes must ensure that they are already meeting both their daily calorie and carbohydrate needs which have been addressed in previous articles.

Building Blocks
Protein is synthesized from amino acids (the building blocks of protein). There are 20 different amino acids (AA) that, in various combinations, create the different types of protein. What makes a particular protein source unique is how these AAs are combined.

There are two major categories of AAs: Essential and Nonessential.

Essential AAs cannot be made in the body therefore they must be supplied by the diet.
The essential AAs are Histidine, Isoleucine*, Leucine*, Lysine, Methionine, Phenylalanine, Threonine, Tryptphan and Valine*

Food sources that contain all of the essential AAs are commonly referred to as “complete” proteins. These foods include animal proteins such as meat, fish, dairy products and eggs.

Side note: (BCAA) Branch chain amino acids (denoted with the * above) are essential AAs of interest to many endurance athletes as they are thought to play a role in mental “strength” and delaying fatigue. BCAAs are stored in the muscle and can be used as fuel during long training days and for 70.3 to Ironman races,particularly if carbohydrate intake falls short.

In theory, BCAAs supplementation (in the form of protein containing sports drinks) seems to make sense, but there is very little solid research which confirms a performance benefit. Consuming sports drinks with protein is not harmful. The biggest subjective issue I have encountered with Ironman athletes is taste. Sports drinks containing protein do not taste so swell after a few hours roasting in the heat. If an athlete is not keen on the taste of their sports drink, they most likely will not drink enough, which can be problematic on race day!

So the burning question: is a protein containing sports drink really needed during endurance training? The answer is no. With that said, I do know of many athletes who swear by their carb/protein potion. So as they say “if it ain’t broke, don’t fuss with it”.

Nonessential amino acids are just as important as essential AAs with the difference being these AAs CAN be made by the body and do not have to come from the diet. Nonessential AAs s are Alanine, Arginine, Asparagine, Aspartic acid, Cysteine, Glutamine, Glutamic Acid, Glycine, Proline, Serine and Tyrosine.

Food sources that may be lacking in one or more of the essential AAs is referred to as “incomplete” proteins. All plant sources of protein (beans, legumes, whole grains, vegetables, nuts and seeds) with the exception of soy are considered incomplete.

Athletes that choose to follow a plant based (vegetarian) training diet should include soy products and incorporate variety in selecting beans/ legumes, whole grains and vegetables. Protein needs CAN be met following a vegetarian diet but these athletes have to ensure they compliment their grain choices with their meat alternative choices so that all the AAs are being supplied over the course of the day.

Protein Requirements
In spite of popular belief, endurance athletes can meet their protein needs without tons of dietary supplements.

The keys to meeting protein needs are 1) knowing how much protein to aim for 2) learning more about the protein content of various foods and 3) planning meals … which can be easier said than done!

Athlete protein needs are based on lean body weight (preferred over total body weight), the type of training (strength/power vs. endurance) and phase of training (base/ build/peak/race). Athletes new to physical training, in general will have a slightly higher protein need than those athletes who have more training experience.

The average athlete may only need the recommended 0.8 gm protein per kilogram body weight per day.

However the very nature of preparing for the 70.3 and Ironman distances will most certainly require a bit more to mend a body battered from 12 to 20+ weekly training hours.

The chart below can be used as a guide to estimate daily protein needs based on the daily training volume. It would be fair to say that athletes who have shorter, more intense, workouts which produce some degree of muscle damage (i.e. muscle soreness) may benefit from that next higher level of protein intake.

 

Daily Training

 

Grams per pound body weight

 

Grams per kilogram (kg) body weight

Up to 60 min per day

0.5

1.1

Between 1 to 2 hours

0.6

1.3

Between 2 to 3 hours

0.7

1.5

Greater than 3 hours

0.8

1.8

 

More is not better
Most athletes with a well balanced diet can easily meet their daily protein requirements. It is a common practice for some athletes to over consume protein believing this in turn will help boost lean body mass. The truth is that the body does not store excess dietary protein as muscle. Once dietary protein has fulfilled its role the excess is broken down and goes to be used as fuel, stored as body fat or excreted by the body via urine.

Protein content of various foods
Oils – none
Fruit- minimal
Grains- 3 grams per serving (1 sl bread, ½ c rice or pasta)
Nuts – 5 grams per 1 oz
Milk/Dairy/ Milk Alternative- 5 to 8 grams per serving (8 oz milk, 6 oz yogurt, 1 oz cheese) Cottage Cheese- 14 grams per ½ cup
Beans – 7 to 8 grams per ½ cup
Meat Alternative/ Soy – 16 to 20 grams per ½ c ( tofu, tempeh) 1 Egg – 7 to 9 grams
Meat – 21 to 27 grams per 3 oz cooked (beef, chicken, turkey, fish, pork)

How much is a portion? For most normal size athletes, the inside diameter of your hand and thickness of your palm is your rough guide to a meat portion appropriate for you.

Nutrition tips for meeting daily protein needs:

Include a protein containing food at every meal and every post workout snack.

To optimize the recovery process, target 10-20 grams of protein (along with the carbohydrate source) in post workout snacks.

Breakfast Ideas
· High protein cereal (ex: Kashi Go Lean), low fat dairy/soy (milk, yogurt)
· Scrambled egg white omelet w/ low fat cheese
· Add 1 scoop soy/ whey protein isolate powder to your hot cereal
· Use milk or soymilk instead of water for hot cereal.

Lunch Ideas
· Turkey/ Tuna/ Chicken Wrap, Beans & Rice, Bean Burrito
· Add part skim mozzarella cheese, crumbled tofu or chickpeas to salads
· Eating out? Request double meat on your sandwiches.

Dinner Ideas
· Tofu Stir Fry w/ Brown Rice, All Bean Chili w/ Rice
· Grilled Chicken, Lean Beef, Pork, Baked Fish with Potatoes or Pasta
· Quinoa and Black Beans served with shredded lowfat soy cheese

Snack Ideas
· Low fat Cheese, Cottage Cheese, Low fat Yogurt with fruit
· Chocolate Milk, Smoothie made w/ Soymilk
· Whole Grain Toast/ Muffin with Peanut or Almond butter

Adequate daily protein is crucial for athletes to maintain a strong, healthy and powerful body. Knowing what your daily needs are is one thing, but knowing you are consuming adequate protein on a daily basis is another. Make use of the many good online resources and lists that can be found that identify the quantity of protein contained in various foods and track your daily intake of not only protein but also carbohydrate and fat as previously discussed in the past couple Ironman.com nutrition articles. If all the numbers and calculations leave you with a headache then consider adding a sports dietitian to your personal performance enhancement team. The use of a qualified sports nutrition professional, like that of a skilled endurance coach can help you take the guess work out of your daily and weekly eating plan and allow you to focus on what most Ironman and 70.3 athletes enjoy the most……..train, eat, sleep and race.

Jennifer Hutchison, RD, CSSD is Board Certified as a Specialist in Sports Dietetics, a USA Triathlon Certified Level 3 Elite Coach. As a Registered Dietitian, Jennifer uses her academic training, certifications and “real world” experience to help fuel athletes worldwide. You can direct comments, questions or suggestions for further articles to Jennifer via email to eSportsRD@aol.com or go to www.IronCladCoaching.com . References available upon request.

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10 for the Road: Essential Nutrients for Endurance Athletes

August 12, 2009 
Filed under Crossfit, Diet And Nutrition, Running, Triathlon

1 Comment

book cover sports nutrition for endurance athletes by monique ryan 10 for the Road: Essential Nutrients for Endurance Athletes

By Alan Christianson, N.D

Quite simply, athletes need more nutrients than less-active people. They demand more from their bodies than even average fitness buffs and so must compensate with the right nutrients from foods or supplements to keep performance—and recovery—at its peak.

The more intense the exercise or sport, the greater the body's nutrient needs. Athletes who participate in endurance sports—those that involve more than one hour of consistent activity—have specific needs because of what they demand from their bodies. For example, athletes lose more electrolytes, such as magnesium, potassium and sodium, through perspiration and must diligently replace them. The wear and tear of intense activity may necessitate increased intake of antioxidants such as vitamin E, which can help protect muscle cells from oxidative damage. Since muscle-tissue breakdown is common during intense exercise, athletes also need more proteins to repair the tissues.

 

To keep their bodies performing optimally, endurance athletes should be familiar with these 10 important nutrients.

The first seven essential supplements are the minerals calcium, iron, magnesium, potassium, selenium, sodium and zinc. Their benefits range from keeping bones strong to minimizing fatigue.

 

  • CALCIUM This may be the most important nutrient for an athlete. In a survey of more than 10,000 male and female athletes ages 7 to 50, fewer than half consumed 1,000 mg of calcium daily.1 The recommended dietary intake ranges from 1,000 to 1,500 mg/day depending on age and gender.

For female athletes, calcium intake is of particular concern. Excessive training—more than seven hours per week—may cause hormonal declines in young girls that can stop menstruation. This hormonal decline also compromises bone formation, possibly leading to premature, irreversible osteoporosis.2 Recent research shows that male endurance athletes of all ages experience testosterone deficits that also can cause osteoporosis.3

Athletes should monitor their calcium intake. Dairy foods can supply the required amounts unless sensitivities exclude them from the diet. But a diet without dairy foods requires supplements. All athletes should make sure they get 1,200 to 1,500 mg of calcium daily from food or supplements. Drinking a cup of skim milk, for example, provides about 300 mg of calcium.

 

  • IRON For the casual athlete who trains less than four hours per week, iron deficiency is no more of a concern than for a sedentary person. But athletes who train for six or more hours per week often have iron-deficiency anemia and should be checked yearly for the condition. Female athletes who are unable to correct such mild anemia through diet can benefit from supplements.4

 

(26.2 miles)
Triathlons

(swim, bike, run)
Ultramarathons

(50 or 100 miles) Athletes use iron stores more quickly than nonathletes and, considering the neurologic effects of anemia on children and teens who engage in rigorous sports, adequate intake of iron is quite important.5 The recommended dietary allowance (RDA) for iron ranges from 10 to 15 mg/day—an amount easily acquired from food. In the absence of anemia, athletes shouldn't take any supplemental iron because it raises the risk of heart disease and colon cancer.

 

  • MAGNESIUM This mineral is involved in adenosine triphosphate (ATP) production from fatty acid oxidation, post-contractile muscular relaxation, and bone remineralization. It is also involved in phosphatidylglycerol (DPG) production, which is important to red blood cell formation. ATP, present in all cells but particularly in muscle cells, stores energy. Low magnesium levels can acutely contribute to early fatigue, nausea and muscle cramps. Chronic magnesium deficiencies can lead to increased osteoporosis risk and anemia.6

Athletes lose magnesium through sweat and urine. This, combined with the fact that athletes' diets are usually low in magnesium, generally leads to the need for supplementation.7 Recommended intake for endurance athletes is 500 to 800 mg daily.8 Higher doses can cause diarrhea.

 

  • POTASSIUM This mineral, present in intracellular fluid, is responsible for regulating total body water and stabilizing controlled and automatic muscle contractions. It is also lost through sweat and urine.

In a study of athletes running 40 minutes at 70 degrees Fahrenheit, potassium loss was estimated at 435 mg/hour. The rate of potassium loss is approximately 200 mg/kg of weight lost during exercise.9

Cells release potassium into the bloodstream and serum levels rise with exercise, possibly instigating fatigue. Potassium supplementation after short events (less than two hours), and during and after long events, is warranted.10 For postactivity replacement, athletes should take about 435 mg/hour of exercise or 200 mg/kg of weight loss. As much as 150 mg/hour during activity can be tolerated by most athletes. Supplement potassium cautiously because too much too quickly can cause cardiac arrest.

Supplementing with potassium during training does increase markers of recovery, primarily serum lactate and muscle hydration, but does not aid performance.10

 

  • SELENIUM Essential to antioxidant glutathione peroxidase (SeGPx) production, selenium is a free radical-scavenging tripeptide made up of glutamine, cysteine and glycine. It is concentrated in the lining of the GI tract and lungs, in the liver, and in skeletal muscle. In an animal study, reducing muscular SeGPx increased cellular damage from prolonged exercise, supporting the theory that free radical-induced muscle damage causes muscle fatigue.11

Research shows selenium benefits athletes' immune function and helps repair cellular damage. Researchers studied the selenium supplementation effects on muscle SeGPx in 24 healthy nonsmoking males. Half took 240 mcg of sodium selenite; half took placebo. After cycling to exhaustion—durations ranged from 2.6 to 3.5 hours—the group that took selenium showed less cellular damage.12

Supplementation with 200 mcg of selenium is safe and warranted for endurance athletes.13

 

  • SODIUM This element helps cells retain water and prevents dehydration. Sodium also enables ATP generation. For events lasting longer than five hours, especially in hot weather, hyponatremia (dangerously low sodium) is a real concern. This especially applies to first-time or slower-running marathoners. Most organized events have aid stations with salty snacks. Anyone out for more than a few hours, especially on a warm day, should make sure to get some salt from snacks and fluid-replacement drinks.

A prospective study was performed on 36 athletes during a three- to four-hour triathlon and 64 athletes at an ironman race, which lasts between nine and 15 hours. No athletes were hyponatremic after the shorter race, but 27 percent were hyponatremic following the ironman. An average of 17 percent of the ironman participants required medical attention, most for hyponatremia.14

Extrapolated from that study, athletes should aim for 80 to 100 mg sodium per quart of hydrating beverage and 100 to 300 mg sodium per hour from other sources.

 

  • ZINC This mineral aids in post-exertion tissue repair and in the conversion of food to fuel. Both male and female athletes have lower serum zinc levels compared with sedentary individuals. Studies correlate endurance exercise with periods of compromised immunity—zinc depletion may be one reason.15

Those who train without days off lose zinc even more quickly. In a study of cyclists, researchers looked at zinc excretion via sweat. Half of the group underwent intense training for two months. Half underwent moderate training with two to three days off per week. Both groups were studied before and after. The exercising group showed increased zinc excretion while the control group showed no increase.16 The researchers believe altered zinc metabolism coupled with increased zinc excretion and stress levels lead to fatigue and decreased endurance.

Athletes should take 30 to 60 mg zinc daily.17 Zinc picolinate or monomethionate are most easily tolerated.18

Prevent Oxidative Damage
Antioxidants are another set of nutrients that endurance athletes are wise to use.

 

  • VITAMIN E For athletes, one of the most important antioxidants is vitamin E. Aerobic athletes may have an increased need for this vitamin because their cells undergo more oxidative damage. Research shows athletes have less cellular damage when they ingest more vitamin E.19 Aerobic exercise places additional demands on the molecular free radical scavengers of the body, and vitamin E is a well-known scavenger.

In a study of 30 top-class cyclists, five months of supplementation with natural vitamin E (alpha-tocopherol) at an 800-IU daily dose significantly decreased markers of oxidative damage to muscle tissue. However, vitamin E did not benefit athletic performance.

Studies evaluating vitamin E as an ergogenic, or performance aid, show no benefit.19 One possible exception is at higher altitudes where oxidative stress is more intense. A group of six mountain climbers took 400 mg synthetic vitamin E (dl-alpha-tocopherol acetate). During exertion at altitude, they showed less output of pentane and lactic acid—both markers of oxidative damage, but not suggestive of improved athletic performance. The athletes also showed a statistically significant increase in anaerobic threshold compared to a placebo group.20

The amount of vitamin E necessary to benefit athletes is not obtainable through diet. The jury is still out on natural vs. synthetic vitamin E, but endurance athletes should take 400 to 800 IU/day.

Protein and Glutamine
Without adequate protein and glutamine, athletes can feel the effects of reduced metabolism, poorer recovery times and increased susceptibility to infections.

 

  • PROTEIN The RDA for protein is 60 mg per day for adults (specifically 0.8 g/kg of body weight/day). This recommendation, however, is based on the needs of sedentary individuals. Recent studies indicate that protein needs increase during strenuous activity, which applies to both strength and endurance athletes.21

Endurance athletes need more protein for different reasons than strength athletes do. Endurance athletes primarily use protein for maintaining aerobic metabolism, compared with the increased tissue-repair needs of strength athletes. When intake is inadequate, the body sequesters the needed proteins from lean tissue, which gives overtrained endurance athletes a gaunt appearance. A protein deficit also impairs an athlete's recovery and wound-healing ability.14

Researchers recommend endurance athletes eat 1.2 to 1.4 g/kg of body weight/day of protein.22 For a 155-pound athlete, this means a total of 85 to 100 g protein per day. Only a few studies recommend protein intake levels as high as 2 g/kg of body weight/day.23

 

  • GLUTAMINE This amino acid increases the numbers of lymphocytes and macrophages. When glutamine levels are low these immune cells show depressed activity.24 Prolonged exercise consistently lowers glutamine levels. Glutamine supplementation reduces vulnerability to infections after prolonged exercise, though a few studies examining this phenomenon at lower exercise intensity levels have not shown benefit.25

Oral glutamine replacement after exercise can lower infection risk. In one study, 200 runners and rowers were given placebo or 2,000 mg glutamine two hours after exercise. In the seven days following the exercise, 81 percent of the glutamine-supplemented group were infection-free compared to 49 percent in the placebo group.26

A supplement that provides 2 g glutamine daily is a wise choice for athletes in training.26

Athletes who train strenuously for competition have greater nutritional needs than sedentary people. Adequate nutrients can mean quicker recovery time, lower infection rates, less fatigue, and ultimately, can help athletes reach their desired performance levels.

 

Alan Christianson, N.D., has a naturopathic private practice in Scottsdale, Ariz.

References

1. Guezennec CY, et al. Is there a relationship between physical activity and dietary calcium intake? A survey in 10,373 young French subjects. Med Sci Sports Exerc 1998 May;30(5):732-9.

2. Voss LA, et al. Exercise-induced loss of bone density in athletes. J Am Acad Orthop Surg 1998 Nov-Dec;6(6):349-57.

3. Bennell KL, et al. Effect of altered reproductive function and lowered testosterone levels on bone density in male endurance athletes. Br J Sports Med 1996 Sep;30(3):205-8.

4. Eichner ER. Sports anemia, iron supplements, and blood doping. Med Sci Sports Exerc 1992 Sep;24(9 Suppl):S315-8.

5. Weaver CM, et al. Exercise and iron status. J Nutr 1992 Mar;122(3 Suppl):782-7.

6. Altura BM, et al. Magnesium depletion impairs myocardial carbohydrate and lipid metabolism and cardiac bioenergetics and raises myocardial calcium content in-vivo: relationship to etiology of cardiac diseases. Biochem Mol Biol Int 1996 Dec;40(6):1183-90.

7. Lukaski HC, et al. Micronutrients (magnesium, zinc, and copper): are mineral supplements needed for athletes? Int J Sport Nutr, 1995;5 Suppl:S74-83.

8. Seelig M. Magnesium deficiency in the pathogenesis of disease. New York: Plenum Press; 1980.

9. Wenk C, et al. Methodological studies of the estimation of loss of sodium, potassium, calcium and magnesium through the skin during a 10 km run. Z Ernahrungswiss 1993 Dec;(4):301-7.

10. Tarnopolsky MA, et al. Mixed carbohydrate supplementation increases carbohydrate oxidation and endurance exercise performance and attenuates potassium accumulation. Int J Sport Nutr 1996 Dec;(4):323-36.

11. Venditti P. Effect of training on antioxidant capacity, tissue damage, and endurance of adult male rats. Int J Sports Med 1997 Oct;18(7):497-502.

12. Tessier F, et al. Muscle GSH-Px activity after prolonged exercise, training, and selenium supplementation. Biol Trace Elem Res, 1995 Jan-Mar;47(1-3):279-85.

13. Persson-Moschos M, et al. Plasma selenoprotein P levels of healthy males in different selenium status after oral supplementation with different forms of selenium. Eur J Clin Nutr 1998 May;52(5):363-7.

14. Hiller WD, et al. Medical and physiological considerations in triathlons. Am J Sports Med 1987 Mar;(2):164-7.

15. Cordova A. Behaviour of zinc in physical exercise: a special reference to immunity and fatigue. Neurosci Biobehav Rev 1995 Fall;19(3):439-45.

16. Cordova A, et al. Effect of training on zinc metabolism: changes in serum and sweat zinc concentrations in sportsmen. Ann Nutr Metab 1998;42(5):274-82.

17. Barrie SA, et al. Comparative absorption of zinc picolinate, zinc citrate and zinc gluconate in humans. Agents Actions 1987;21(1-2):223-8.

18. Rohde T, et al. Effect of glutamine supplementation on changes in the immune system induced by repeated exercise. Med Sci Sports Exerc 1998 Jun;30(6):856-62.

19. Rokitzki L, et al. Alpha-tocopherol supplementation in racing cyclists during extreme endurance training. Int J Sport Nutr 1994 Sep;4(3):253-64.

20. Simon-Schnass I, et al. Influence of vitamin E on physical performance. Int J Vitam Nutr Res 1988;58(1):49-54.

21. Lemon PW, et al. Do athletes need more dietary protein and amino acids? Int J Sport Nutr 1995 Jun;5 Suppl:S39-61.

22. Shephard, RJ, et al. Immunological hazards from nutritional imbalance in athletes. Exerc Immunol Rev 1998;4:22-48.

23. Rohde T, et al. The immune system and serum glutamine during a triathlon. Eur J Appl Physiol 1996;74(5):428-34.

24. Newsholme EA, et al. The proposed role of glutamine in some cells of the immune system and speculative consequences for the whole animal. Nutrition 1997 Jul-Aug; 13(7-8):728-30.

25.Rohde T, et al. Effect of glutamine supplementation on changes in the immune system induced by repeated exercise. Med Sci Sports Exerc 1998 Jun;30(6):856-62.

26.Castell LM, et al. Does glutamine have a role in reducing infections in athletes? Eur J Appl Physiol 1996;73(5):488-90.

 

 

  • MAGNESIUM This mineral is involved in adenosine triphosphate (ATP) production from fatty acid oxidation, post-contractile muscular relaxation, and bone remineralization. It is also involved in phosphatidylglycerol (DPG) production, which is important to red blood cell formation. ATP, present in all cells but particularly in muscle cells, stores energy. Low magnesium levels can acutely contribute to early fatigue, nausea and muscle cramps. Chronic magnesium deficiencies can lead to increased osteoporosis risk and anemia.6

Athletes lose magnesium through sweat and urine. This, combined with the fact that athletes' diets are usually low in magnesium, generally leads to the need for supplementation.7 Recommended intake for endurance athletes is 500 to 800 mg daily.8 Higher doses can cause diarrhea.

 

  • POTASSIUM This mineral, present in intracellular fluid, is responsible for regulating total body water and stabilizing controlled and automatic muscle contractions. It is also lost through sweat and urine.

In a study of athletes running 40 minutes at 70 degrees Fahrenheit, potassium loss was estimated at 435 mg/hour. The rate of potassium loss is approximately 200 mg/kg of weight lost during exercise.9

Cells release potassium into the bloodstream and serum levels rise with exercise, possibly instigating fatigue. Potassium supplementation after short events (less than two hours), and during and after long events, is warranted.10 For postactivity replacement, athletes should take about 435 mg/hour of exercise or 200 mg/kg of weight loss. As much as 150 mg/hour during activity can be tolerated by most athletes. Supplement potassium cautiously because too much too quickly can cause cardiac arrest.

Supplementing with potassium during training does increase markers of recovery, primarily serum lactate and muscle hydration, but does not aid performance.10

 

  • SELENIUM Essential to antioxidant glutathione peroxidase (SeGPx) production, selenium is a free radical-scavenging tripeptide made up of glutamine, cysteine and glycine. It is concentrated in the lining of the GI tract and lungs, in the liver, and in skeletal muscle. In an animal study, reducing muscular SeGPx increased cellular damage from prolonged exercise, supporting the theory that free radical-induced muscle damage causes muscle fatigue.11

Research shows selenium benefits athletes' immune function and helps repair cellular damage. Researchers studied the selenium supplementation effects on muscle SeGPx in 24 healthy nonsmoking males. Half took 240 mcg of sodium selenite; half took placebo. After cycling to exhaustion—durations ranged from 2.6 to 3.5 hours—the group that took selenium showed less cellular damage.12

Supplementation with 200 mcg of selenium is safe and warranted for endurance athletes.13

 

  • SODIUM This element helps cells retain water and prevents dehydration. Sodium also enables ATP generation. For events lasting longer than five hours, especially in hot weather, hyponatremia (dangerously low sodium) is a real concern. This especially applies to first-time or slower-running marathoners. Most organized events have aid stations with salty snacks. Anyone out for more than a few hours, especially on a warm day, should make sure to get some salt from snacks and fluid-replacement drinks.

A prospective study was performed on 36 athletes during a three- to four-hour triathlon and 64 athletes at an ironman race, which lasts between nine and 15 hours. No athletes were hyponatremic after the shorter race, but 27 percent were hyponatremic following the ironman. An average of 17 percent of the ironman participants required medical attention, most for hyponatremia.14

Extrapolated from that study, athletes should aim for 80 to 100 mg sodium per quart of hydrating beverage and 100 to 300 mg sodium per hour from other sources.

 

  • ZINC This mineral aids in post-exertion tissue repair and in the conversion of food to fuel. Both male and female athletes have lower serum zinc levels compared with sedentary individuals. Studies correlate endurance exercise with periods of compromised immunity—zinc depletion may be one reason.15

Those who train without days off lose zinc even more quickly. In a study of cyclists, researchers looked at zinc excretion via sweat. Half of the group underwent intense training for two months. Half underwent moderate training with two to three days off per week. Both groups were studied before and after. The exercising group showed increased zinc excretion while the control group showed no increase.16 The researchers believe altered zinc metabolism coupled with increased zinc excretion and stress levels lead to fatigue and decreased endurance.

Athletes should take 30 to 60 mg zinc daily.17 Zinc picolinate or monomethionate are most easily tolerated.18

Prevent Oxidative Damage
Antioxidants are another set of nutrients that endurance athletes are wise to use.

 

  • VITAMIN E For athletes, one of the most important antioxidants is vitamin E. Aerobic athletes may have an increased need for this vitamin because their cells undergo more oxidative damage. Research shows athletes have less cellular damage when they ingest more vitamin E.19 Aerobic exercise places additional demands on the molecular free radical scavengers of the body, and vitamin E is a well-known scavenger.

In a study of 30 top-class cyclists, five months of supplementation with natural vitamin E (alpha-tocopherol) at an 800-IU daily dose significantly decreased markers of oxidative damage to muscle tissue. However, vitamin E did not benefit athletic performance.

Studies evaluating vitamin E as an ergogenic, or performance aid, show no benefit.19 One possible exception is at higher altitudes where oxidative stress is more intense. A group of six mountain climbers took 400 mg synthetic vitamin E (dl-alpha-tocopherol acetate). During exertion at altitude, they showed less output of pentane and lactic acid—both markers of oxidative damage, but not suggestive of improved athletic performance. The athletes also showed a statistically significant increase in anaerobic threshold compared to a placebo group.20

The amount of vitamin E necessary to benefit athletes is not obtainable through diet. The jury is still out on natural vs. synthetic vitamin E, but endurance athletes should take 400 to 800 IU/day.

Protein and Glutamine
Without adequate protein and glutamine, athletes can feel the effects of reduced metabolism, poorer recovery times and increased susceptibility to infections.

 

  • PROTEIN The RDA for protein is 60 mg per day for adults (specifically 0.8 g/kg of body weight/day). This recommendation, however, is based on the needs of sedentary individuals. Recent studies indicate that protein needs increase during strenuous activity, which applies to both strength and endurance athletes.21

Endurance athletes need more protein for different reasons than strength athletes do. Endurance athletes primarily use protein for maintaining aerobic metabolism, compared with the increased tissue-repair needs of strength athletes. When intake is inadequate, the body sequesters the needed proteins from lean tissue, which gives overtrained endurance athletes a gaunt appearance. A protein deficit also impairs an athlete's recovery and wound-healing ability.14

Researchers recommend endurance athletes eat 1.2 to 1.4 g/kg of body weight/day of protein.22 For a 155-pound athlete, this means a total of 85 to 100 g protein per day. Only a few studies recommend protein intake levels as high as 2 g/kg of body weight/day.23

 

  • GLUTAMINE This amino acid increases the numbers of lymphocytes and macrophages. When glutamine levels are low these immune cells show depressed activity.24 Prolonged exercise consistently lowers glutamine levels. Glutamine supplementation reduces vulnerability to infections after prolonged exercise, though a few studies examining this phenomenon at lower exercise intensity levels have not shown benefit.25

Oral glutamine replacement after exercise can lower infection risk. In one study, 200 runners and rowers were given placebo or 2,000 mg glutamine two hours after exercise. In the seven days following the exercise, 81 percent of the glutamine-supplemented group were infection-free compared to 49 percent in the placebo group.26

A supplement that provides 2 g glutamine daily is a wise choice for athletes in training.26

Athletes who train strenuously for competition have greater nutritional needs than sedentary people. Adequate nutrients can mean quicker recovery time, lower infection rates, less fatigue, and ultimately, can help athletes reach their desired performance levels.

 

Alan Christianson, N.D., has a naturopathic private practice in Scottsdale, Ariz.

References

1. Guezennec CY, et al. Is there a relationship between physical activity and dietary calcium intake? A survey in 10,373 young French subjects. Med Sci Sports Exerc 1998 May;30(5):732-9.

2. Voss LA, et al. Exercise-induced loss of bone density in athletes. J Am Acad Orthop Surg 1998 Nov-Dec;6(6):349-57.

3. Bennell KL, et al. Effect of altered reproductive function and lowered testosterone levels on bone density in male endurance athletes. Br J Sports Med 1996 Sep;30(3):205-8.

4. Eichner ER. Sports anemia, iron supplements, and blood doping. Med Sci Sports Exerc 1992 Sep;24(9 Suppl):S315-8.

5. Weaver CM, et al. Exercise and iron status. J Nutr 1992 Mar;122(3 Suppl):782-7.

6. Altura BM, et al. Magnesium depletion impairs myocardial carbohydrate and lipid metabolism and cardiac bioenergetics and raises myocardial calcium content in-vivo: relationship to etiology of cardiac diseases. Biochem Mol Biol Int 1996 Dec;40(6):1183-90.

7. Lukaski HC, et al. Micronutrients (magnesium, zinc, and copper): are mineral supplements needed for athletes? Int J Sport Nutr, 1995;5 Suppl:S74-83.

8. Seelig M. Magnesium deficiency in the pathogenesis of disease. New York: Plenum Press; 1980.

9. Wenk C, et al. Methodological studies of the estimation of loss of sodium, potassium, calcium and magnesium through the skin during a 10 km run. Z Ernahrungswiss 1993 Dec;(4):301-7.

10. Tarnopolsky MA, et al. Mixed carbohydrate supplementation increases carbohydrate oxidation and endurance exercise performance and attenuates potassium accumulation. Int J Sport Nutr 1996 Dec;(4):323-36.

11. Venditti P. Effect of training on antioxidant capacity, tissue damage, and endurance of adult male rats. Int J Sports Med 1997 Oct;18(7):497-502.

12. Tessier F, et al. Muscle GSH-Px activity after prolonged exercise, training, and selenium supplementation. Biol Trace Elem Res, 1995 Jan-Mar;47(1-3):279-85.

13. Persson-Moschos M, et al. Plasma selenoprotein P levels of healthy males in different selenium status after oral supplementation with different forms of selenium. Eur J Clin Nutr 1998 May;52(5):363-7.

14. Hiller WD, et al. Medical and physiological considerations in triathlons. Am J Sports Med 1987 Mar;(2):164-7.

15. Cordova A. Behaviour of zinc in physical exercise: a special reference to immunity and fatigue. Neurosci Biobehav Rev 1995 Fall;19(3):439-45.

16. Cordova A, et al. Effect of training on zinc metabolism: changes in serum and sweat zinc concentrations in sportsmen. Ann Nutr Metab 1998;42(5):274-82.

17. Barrie SA, et al. Comparative absorption of zinc picolinate, zinc citrate and zinc gluconate in humans. Agents Actions 1987;21(1-2):223-8.

18. Rohde T, et al. Effect of glutamine supplementation on changes in the immune system induced by repeated exercise. Med Sci Sports Exerc 1998 Jun;30(6):856-62.

19. Rokitzki L, et al. Alpha-tocopherol supplementation in racing cyclists during extreme endurance training. Int J Sport Nutr 1994 Sep;4(3):253-64.

20. Simon-Schnass I, et al. Influence of vitamin E on physical performance. Int J Vitam Nutr Res 1988;58(1):49-54.

21. Lemon PW, et al. Do athletes need more dietary protein and amino acids? Int J Sport Nutr 1995 Jun;5 Suppl:S39-61.

22. Shephard, RJ, et al. Immunological hazards from nutritional imbalance in athletes. Exerc Immunol Rev 1998;4:22-48.

23. Rohde T, et al. The immune system and serum glutamine during a triathlon. Eur J Appl Physiol 1996;74(5):428-34.

24. Newsholme EA, et al. The proposed role of glutamine in some cells of the immune system and speculative consequences for the whole animal. Nutrition 1997 Jul-Aug; 13(7-8):728-30.

25.Rohde T, et al. Effect of glutamine supplementation on changes in the immune system induced by repeated exercise. Med Sci Sports Exerc 1998 Jun;30(6):856-62.

26.Castell LM, et al. Does glutamine have a role in reducing infections in athletes? Eur J Appl Physiol 1996;73(5):488-90.

 

 

  • MAGNESIUM This mineral is involved in adenosine triphosphate (ATP) production from fatty acid oxidation, post-contractile muscular relaxation, and bone remineralization. It is also involved in phosphatidylglycerol (DPG) production, which is important to red blood cell formation. ATP, present in all cells but particularly in muscle cells, stores energy. Low magnesium levels can acutely contribute to early fatigue, nausea and muscle cramps. Chronic magnesium deficiencies can lead to increased osteoporosis risk and anemia.6

Athletes lose magnesium through sweat and urine. This, combined with the fact that athletes' diets are usually low in magnesium, generally leads to the need for supplementation.7 Recommended intake for endurance athletes is 500 to 800 mg daily.8 Higher doses can cause diarrhea.

 

  • POTASSIUM This mineral, present in intracellular fluid, is responsible for regulating total body water and stabilizing controlled and automatic muscle contractions. It is also lost through sweat and urine.

In a study of athletes running 40 minutes at 70 degrees Fahrenheit, potassium loss was estimated at 435 mg/hour. The rate of potassium loss is approximately 200 mg/kg of weight lost during exercise.9

Cells release potassium into the bloodstream and serum levels rise with exercise, possibly instigating fatigue. Potassium supplementation after short events (less than two hours), and during and after long events, is warranted.10 For postactivity replacement, athletes should take about 435 mg/hour of exercise or 200 mg/kg of weight loss. As much as 150 mg/hour during activity can be tolerated by most athletes. Supplement potassium cautiously because too much too quickly can cause cardiac arrest.

Supplementing with potassium during training does increase markers of recovery, primarily serum lactate and muscle hydration, but does not aid performance.10

 

  • SELENIUM Essential to antioxidant glutathione peroxidase (SeGPx) production, selenium is a free radical-scavenging tripeptide made up of glutamine, cysteine and glycine. It is concentrated in the lining of the GI tract and lungs, in the liver, and in skeletal muscle. In an animal study, reducing muscular SeGPx increased cellular damage from prolonged exercise, supporting the theory that free radical-induced muscle damage causes muscle fatigue.11

Research shows selenium benefits athletes' immune function and helps repair cellular damage. Researchers studied the selenium supplementation effects on muscle SeGPx in 24 healthy nonsmoking males. Half took 240 mcg of sodium selenite; half took placebo. After cycling to exhaustion—durations ranged from 2.6 to 3.5 hours—the group that took selenium showed less cellular damage.12

Supplementation with 200 mcg of selenium is safe and warranted for endurance athletes.13

 

  • SODIUM This element helps cells retain water and prevents dehydration. Sodium also enables ATP generation. For events lasting longer than five hours, especially in hot weather, hyponatremia (dangerously low sodium) is a real concern. This especially applies to first-time or slower-running marathoners. Most organized events have aid stations with salty snacks. Anyone out for more than a few hours, especially on a warm day, should make sure to get some salt from snacks and fluid-replacement drinks.

A prospective study was performed on 36 athletes during a three- to four-hour triathlon and 64 athletes at an ironman race, which lasts between nine and 15 hours. No athletes were hyponatremic after the shorter race, but 27 percent were hyponatremic following the ironman. An average of 17 percent of the ironman participants required medical attention, most for hyponatremia.14

Extrapolated from that study, athletes should aim for 80 to 100 mg sodium per quart of hydrating beverage and 100 to 300 mg sodium per hour from other sources.

 

  • ZINC This mineral aids in post-exertion tissue repair and in the conversion of food to fuel. Both male and female athletes have lower serum zinc levels compared with sedentary individuals. Studies correlate endurance exercise with periods of compromised immunity—zinc depletion may be one reason.15

Those who train without days off lose zinc even more quickly. In a study of cyclists, researchers looked at zinc excretion via sweat. Half of the group underwent intense training for two months. Half underwent moderate training with two to three days off per week. Both groups were studied before and after. The exercising group showed increased zinc excretion while the control group showed no increase.16 The researchers believe altered zinc metabolism coupled with increased zinc excretion and stress levels lead to fatigue and decreased endurance.

Athletes should take 30 to 60 mg zinc daily.17 Zinc picolinate or monomethionate are most easily tolerated.18

Prevent Oxidative Damage
Antioxidants are another set of nutrients that endurance athletes are wise to use.

 

  • VITAMIN E For athletes, one of the most important antioxidants is vitamin E. Aerobic athletes may have an increased need for this vitamin because their cells undergo more oxidative damage. Research shows athletes have less cellular damage when they ingest more vitamin E.19 Aerobic exercise places additional demands on the molecular free radical scavengers of the body, and vitamin E is a well-known scavenger.

In a study of 30 top-class cyclists, five months of supplementation with natural vitamin E (alpha-tocopherol) at an 800-IU daily dose significantly decreased markers of oxidative damage to muscle tissue. However, vitamin E did not benefit athletic performance.

Studies evaluating vitamin E as an ergogenic, or performance aid, show no benefit.19 One possible exception is at higher altitudes where oxidative stress is more intense. A group of six mountain climbers took 400 mg synthetic vitamin E (dl-alpha-tocopherol acetate). During exertion at altitude, they showed less output of pentane and lactic acid—both markers of oxidative damage, but not suggestive of improved athletic performance. The athletes also showed a statistically significant increase in anaerobic threshold compared to a placebo group.20

The amount of vitamin E necessary to benefit athletes is not obtainable through diet. The jury is still out on natural vs. synthetic vitamin E, but endurance athletes should take 400 to 800 IU/day.

Protein and Glutamine
Without adequate protein and glutamine, athletes can feel the effects of reduced metabolism, poorer recovery times and increased susceptibility to infections.

 

  • PROTEIN The RDA for protein is 60 mg per day for adults (specifically 0.8 g/kg of body weight/day). This recommendation, however, is based on the needs of sedentary individuals. Recent studies indicate that protein needs increase during strenuous activity, which applies to both strength and endurance athletes.21

Endurance athletes need more protein for different reasons than strength athletes do. Endurance athletes primarily use protein for maintaining aerobic metabolism, compared with the increased tissue-repair needs of strength athletes. When intake is inadequate, the body sequesters the needed proteins from lean tissue, which gives overtrained endurance athletes a gaunt appearance. A protein deficit also impairs an athlete's recovery and wound-healing ability.14

Researchers recommend endurance athletes eat 1.2 to 1.4 g/kg of body weight/day of protein.22 For a 155-pound athlete, this means a total of 85 to 100 g protein per day. Only a few studies recommend protein intake levels as high as 2 g/kg of body weight/day.23

 

  • GLUTAMINE This amino acid increases the numbers of lymphocytes and macrophages. When glutamine levels are low these immune cells show depressed activity.24 Prolonged exercise consistently lowers glutamine levels. Glutamine supplementation reduces vulnerability to infections after prolonged exercise, though a few studies examining this phenomenon at lower exercise intensity levels have not shown benefit.25

Oral glutamine replacement after exercise can lower infection risk. In one study, 200 runners and rowers were given placebo or 2,000 mg glutamine two hours after exercise. In the seven days following the exercise, 81 percent of the glutamine-supplemented group were infection-free compared to 49 percent in the placebo group.26

A supplement that provides 2 g glutamine daily is a wise choice for athletes in training.26

Athletes who train strenuously for competition have greater nutritional needs than sedentary people. Adequate nutrients can mean quicker recovery time, lower infection rates, less fatigue, and ultimately, can help athletes reach their desired performance levels.

 

Alan Christianson, N.D., has a naturopathic private practice in Scottsdale, Ariz.

References

1. Guezennec CY, et al. Is there a relationship between physical activity and dietary calcium intake? A survey in 10,373 young French subjects. Med Sci Sports Exerc 1998 May;30(5):732-9.

2. Voss LA, et al. Exercise-induced loss of bone density in athletes. J Am Acad Orthop Surg 1998 Nov-Dec;6(6):349-57.

3. Bennell KL, et al. Effect of altered reproductive function and lowered testosterone levels on bone density in male endurance athletes. Br J Sports Med 1996 Sep;30(3):205-8.

4. Eichner ER. Sports anemia, iron supplements, and blood doping. Med Sci Sports Exerc 1992 Sep;24(9 Suppl):S315-8.

5. Weaver CM, et al. Exercise and iron status. J Nutr 1992 Mar;122(3 Suppl):782-7.

6. Altura BM, et al. Magnesium depletion impairs myocardial carbohydrate and lipid metabolism and cardiac bioenergetics and raises myocardial calcium content in-vivo: relationship to etiology of cardiac diseases. Biochem Mol Biol Int 1996 Dec;40(6):1183-90.

7. Lukaski HC, et al. Micronutrients (magnesium, zinc, and copper): are mineral supplements needed for athletes? Int J Sport Nutr, 1995;5 Suppl:S74-83.

8. Seelig M. Magnesium deficiency in the pathogenesis of disease. New York: Plenum Press; 1980.

9. Wenk C, et al. Methodological studies of the estimation of loss of sodium, potassium, calcium and magnesium through the skin during a 10 km run. Z Ernahrungswiss 1993 Dec;(4):301-7.

10. Tarnopolsky MA, et al. Mixed carbohydrate supplementation increases carbohydrate oxidation and endurance exercise performance and attenuates potassium accumulation. Int J Sport Nutr 1996 Dec;(4):323-36.

11. Venditti P. Effect of training on antioxidant capacity, tissue damage, and endurance of adult male rats. Int J Sports Med 1997 Oct;18(7):497-502.

12. Tessier F, et al. Muscle GSH-Px activity after prolonged exercise, training, and selenium supplementation. Biol Trace Elem Res, 1995 Jan-Mar;47(1-3):279-85.

13. Persson-Moschos M, et al. Plasma selenoprotein P levels of healthy males in different selenium status after oral supplementation with different forms of selenium. Eur J Clin Nutr 1998 May;52(5):363-7.

14. Hiller WD, et al. Medical and physiological considerations in triathlons. Am J Sports Med 1987 Mar;(2):164-7.

15. Cordova A. Behaviour of zinc in physical exercise: a special reference to immunity and fatigue. Neurosci Biobehav Rev 1995 Fall;19(3):439-45.

16. Cordova A, et al. Effect of training on zinc metabolism: changes in serum and sweat zinc concentrations in sportsmen. Ann Nutr Metab 1998;42(5):274-82.

17. Barrie SA, et al. Comparative absorption of zinc picolinate, zinc citrate and zinc gluconate in humans. Agents Actions 1987;21(1-2):223-8.

18. Rohde T, et al. Effect of glutamine supplementation on changes in the immune system induced by repeated exercise. Med Sci Sports Exerc 1998 Jun;30(6):856-62.

19. Rokitzki L, et al. Alpha-tocopherol supplementation in racing cyclists during extreme endurance training. Int J Sport Nutr 1994 Sep;4(3):253-64.

20. Simon-Schnass I, et al. Influence of vitamin E on physical performance. Int J Vitam Nutr Res 1988;58(1):49-54.

21. Lemon PW, et al. Do athletes need more dietary protein and amino acids? Int J Sport Nutr 1995 Jun;5 Suppl:S39-61.

22. Shephard, RJ, et al. Immunological hazards from nutritional imbalance in athletes. Exerc Immunol Rev 1998;4:22-48.

23. Rohde T, et al. The immune system and serum glutamine during a triathlon. Eur J Appl Physiol 1996;74(5):428-34.

24. Newsholme EA, et al. The proposed role of glutamine in some cells of the immune system and speculative consequences for the whole animal. Nutrition 1997 Jul-Aug; 13(7-8):728-30.

25.Rohde T, et al. Effect of glutamine supplementation on changes in the immune system induced by repeated exercise. Med Sci Sports Exerc 1998 Jun;30(6):856-62.

26.Castell LM, et al. Does glutamine have a role in reducing infections in athletes? Eur J Appl Physiol 1996;73(5):488-90.

 

 

  • MAGNESIUM This mineral is involved in adenosine triphosphate (ATP) production from fatty acid oxidation, post-contractile muscular relaxation, and bone remineralization. It is also involved in phosphatidylglycerol (DPG) production, which is important to red blood cell formation. ATP, present in all cells but particularly in muscle cells, stores energy. Low magnesium levels can acutely contribute to early fatigue, nausea and muscle cramps. Chronic magnesium deficiencies can lead to increased osteoporosis risk and anemia.6

Athletes lose magnesium through sweat and urine. This, combined with the fact that athletes' diets are usually low in magnesium, generally leads to the need for supplementation.7 Recommended intake for endurance athletes is 500 to 800 mg daily.8 Higher doses can cause diarrhea.

 

  • POTASSIUM This mineral, present in intracellular fluid, is responsible for regulating total body water and stabilizing controlled and automatic muscle contractions. It is also lost through sweat and urine.

In a study of athletes running 40 minutes at 70 degrees Fahrenheit, potassium loss was estimated at 435 mg/hour. The rate of potassium loss is approximately 200 mg/kg of weight lost during exercise.9

Cells release potassium into the bloodstream and serum levels rise with exercise, possibly instigating fatigue. Potassium supplementation after short events (less than two hours), and during and after long events, is warranted.10 For postactivity replacement, athletes should take about 435 mg/hour of exercise or 200 mg/kg of weight loss. As much as 150 mg/hour during activity can be tolerated by most athletes. Supplement potassium cautiously because too much too quickly can cause cardiac arrest.

Supplementing with potassium during training does increase markers of recovery, primarily serum lactate and muscle hydration, but does not aid performance.10

 

  • SELENIUM Essential to antioxidant glutathione peroxidase (SeGPx) production, selenium is a free radical-scavenging tripeptide made up of glutamine, cysteine and glycine. It is concentrated in the lining of the GI tract and lungs, in the liver, and in skeletal muscle. In an animal study, reducing muscular SeGPx increased cellular damage from prolonged exercise, supporting the theory that free radical-induced muscle damage causes muscle fatigue.11

Research shows selenium benefits athletes' immune function and helps repair cellular damage. Researchers studied the selenium supplementation effects on muscle SeGPx in 24 healthy nonsmoking males. Half took 240 mcg of sodium selenite; half took placebo. After cycling to exhaustion—durations ranged from 2.6 to 3.5 hours—the group that took selenium showed less cellular damage.12

Supplementation with 200 mcg of selenium is safe and warranted for endurance athletes.13

 

  • SODIUM This element helps cells retain water and prevents dehydration. Sodium also enables ATP generation. For events lasting longer than five hours, especially in hot weather, hyponatremia (dangerously low sodium) is a real concern. This especially applies to first-time or slower-running marathoners. Most organized events have aid stations with salty snacks. Anyone out for more than a few hours, especially on a warm day, should make sure to get some salt from snacks and fluid-replacement drinks.

A prospective study was performed on 36 athletes during a three- to four-hour triathlon and 64 athletes at an ironman race, which lasts between nine and 15 hours. No athletes were hyponatremic after the shorter race, but 27 percent were hyponatremic following the ironman. An average of 17 percent of the ironman participants required medical attention, most for hyponatremia.14

Extrapolated from that study, athletes should aim for 80 to 100 mg sodium per quart of hydrating beverage and 100 to 300 mg sodium per hour from other sources.

 

  • ZINC This mineral aids in post-exertion tissue repair and in the conversion of food to fuel. Both male and female athletes have lower serum zinc levels compared with sedentary individuals. Studies correlate endurance exercise with periods of compromised immunity—zinc depletion may be one reason.15

Those who train without days off lose zinc even more quickly. In a study of cyclists, researchers looked at zinc excretion via sweat. Half of the group underwent intense training for two months. Half underwent moderate training with two to three days off per week. Both groups were studied before and after. The exercising group showed increased zinc excretion while the control group showed no increase.16 The researchers believe altered zinc metabolism coupled with increased zinc excretion and stress levels lead to fatigue and decreased endurance.

Athletes should take 30 to 60 mg zinc daily.17 Zinc picolinate or monomethionate are most easily tolerated.18

Prevent Oxidative Damage
Antioxidants are another set of nutrients that endurance athletes are wise to use.

 

  • VITAMIN E For athletes, one of the most important antioxidants is vitamin E. Aerobic athletes may have an increased need for this vitamin because their cells undergo more oxidative damage. Research shows athletes have less cellular damage when they ingest more vitamin E.19 Aerobic exercise places additional demands on the molecular free radical scavengers of the body, and vitamin E is a well-known scavenger.

In a study of 30 top-class cyclists, five months of supplementation with natural vitamin E (alpha-tocopherol) at an 800-IU daily dose significantly decreased markers of oxidative damage to muscle tissue. However, vitamin E did not benefit athletic performance.

Studies evaluating vitamin E as an ergogenic, or performance aid, show no benefit.19 One possible exception is at higher altitudes where oxidative stress is more intense. A group of six mountain climbers took 400 mg synthetic vitamin E (dl-alpha-tocopherol acetate). During exertion at altitude, they showed less output of pentane and lactic acid—both markers of oxidative damage, but not suggestive of improved athletic performance. The athletes also showed a statistically significant increase in anaerobic threshold compared to a placebo group.20

The amount of vitamin E necessary to benefit athletes is not obtainable through diet. The jury is still out on natural vs. synthetic vitamin E, but endurance athletes should take 400 to 800 IU/day.

Protein and Glutamine
Without adequate protein and glutamine, athletes can feel the effects of reduced metabolism, poorer recovery times and increased susceptibility to infections.

 

  • PROTEIN The RDA for protein is 60 mg per day for adults (specifically 0.8 g/kg of body weight/day). This recommendation, however, is based on the needs of sedentary individuals. Recent studies indicate that protein needs increase during strenuous activity, which applies to both strength and endurance athletes.21

Endurance athletes need more protein for different reasons than strength athletes do. Endurance athletes primarily use protein for maintaining aerobic metabolism, compared with the increased tissue-repair needs of strength athletes. When intake is inadequate, the body sequesters the needed proteins from lean tissue, which gives overtrained endurance athletes a gaunt appearance. A protein deficit also impairs an athlete's recovery and wound-healing ability.14

Researchers recommend endurance athletes eat 1.2 to 1.4 g/kg of body weight/day of protein.22 For a 155-pound athlete, this means a total of 85 to 100 g protein per day. Only a few studies recommend protein intake levels as high as 2 g/kg of body weight/day.23

 

  • GLUTAMINE This amino acid increases the numbers of lymphocytes and macrophages. When glutamine levels are low these immune cells show depressed activity.24 Prolonged exercise consistently lowers glutamine levels. Glutamine supplementation reduces vulnerability to infections after prolonged exercise, though a few studies examining this phenomenon at lower exercise intensity levels have not shown benefit.25

Oral glutamine replacement after exercise can lower infection risk. In one study, 200 runners and rowers were given placebo or 2,000 mg glutamine two hours after exercise. In the seven days following the exercise, 81 percent of the glutamine-supplemented group were infection-free compared to 49 percent in the placebo group.26

A supplement that provides 2 g glutamine daily is a wise choice for athletes in training.26

Athletes who train strenuously for competition have greater nutritional needs than sedentary people. Adequate nutrients can mean quicker recovery time, lower infection rates, less fatigue, and ultimately, can help athletes reach their desired performance levels.

 

Alan Christianson, N.D., has a naturopathic private practice in Scottsdale, Ariz.

References

1. Guezennec CY, et al. Is there a relationship between physical activity and dietary calcium intake? A survey in 10,373 young French subjects. Med Sci Sports Exerc 1998 May;30(5):732-9.

2. Voss LA, et al. Exercise-induced loss of bone density in athletes. J Am Acad Orthop Surg 1998 Nov-Dec;6(6):349-57.

3. Bennell KL, et al. Effect of altered reproductive function and lowered testosterone levels on bone density in male endurance athletes. Br J Sports Med 1996 Sep;30(3):205-8.

4. Eichner ER. Sports anemia, iron supplements, and blood doping. Med Sci Sports Exerc 1992 Sep;24(9 Suppl):S315-8.

5. Weaver CM, et al. Exercise and iron status. J Nutr 1992 Mar;122(3 Suppl):782-7.

6. Altura BM, et al. Magnesium depletion impairs myocardial carbohydrate and lipid metabolism and cardiac bioenergetics and raises myocardial calcium content in-vivo: relationship to etiology of cardiac diseases. Biochem Mol Biol Int 1996 Dec;40(6):1183-90.

7. Lukaski HC, et al. Micronutrients (magnesium, zinc, and copper): are mineral supplements needed for athletes? Int J Sport Nutr, 1995;5 Suppl:S74-83.

8. Seelig M. Magnesium deficiency in the pathogenesis of disease. New York: Plenum Press; 1980.

9. Wenk C, et al. Methodological studies of the estimation of loss of sodium, potassium, calcium and magnesium through the skin during a 10 km run. Z Ernahrungswiss 1993 Dec;(4):301-7.

10. Tarnopolsky MA, et al. Mixed carbohydrate supplementation increases carbohydrate oxidation and endurance exercise performance and attenuates potassium accumulation. Int J Sport Nutr 1996 Dec;(4):323-36.

11. Venditti P. Effect of training on antioxidant capacity, tissue damage, and endurance of adult male rats. Int J Sports Med 1997 Oct;18(7):497-502.

12. Tessier F, et al. Muscle GSH-Px activity after prolonged exercise, training, and selenium supplementation. Biol Trace Elem Res, 1995 Jan-Mar;47(1-3):279-85.

13. Persson-Moschos M, et al. Plasma selenoprotein P levels of healthy males in different selenium status after oral supplementation with different forms of selenium. Eur J Clin Nutr 1998 May;52(5):363-7.

14. Hiller WD, et al. Medical and physiological considerations in triathlons. Am J Sports Med 1987 Mar;(2):164-7.

15. Cordova A. Behaviour of zinc in physical exercise: a special reference to immunity and fatigue. Neurosci Biobehav Rev 1995 Fall;19(3):439-45.

16. Cordova A, et al. Effect of training on zinc metabolism: changes in serum and sweat zinc concentrations in sportsmen. Ann Nutr Metab 1998;42(5):274-82.

17. Barrie SA, et al. Comparative absorption of zinc picolinate, zinc citrate and zinc gluconate in humans. Agents Actions 1987;21(1-2):223-8.

18. Rohde T, et al. Effect of glutamine supplementation on changes in the immune system induced by repeated exercise. Med Sci Sports Exerc 1998 Jun;30(6):856-62.

19. Rokitzki L, et al. Alpha-tocopherol supplementation in racing cyclists during extreme endurance training. Int J Sport Nutr 1994 Sep;4(3):253-64.

20. Simon-Schnass I, et al. Influence of vitamin E on physical performance. Int J Vitam Nutr Res 1988;58(1):49-54.

21. Lemon PW, et al. Do athletes need more dietary protein and amino acids? Int J Sport Nutr 1995 Jun;5 Suppl:S39-61.

22. Shephard, RJ, et al. Immunological hazards from nutritional imbalance in athletes. Exerc Immunol Rev 1998;4:22-48.

23. Rohde T, et al. The immune system and serum glutamine during a triathlon. Eur J Appl Physiol 1996;74(5):428-34.

24. Newsholme EA, et al. The proposed role of glutamine in some cells of the immune system and speculative consequences for the whole animal. Nutrition 1997 Jul-Aug; 13(7-8):728-30.

25.Rohde T, et al. Effect of glutamine supplementation on changes in the immune system induced by repeated exercise. Med Sci Sports Exerc 1998 Jun;30(6):856-62.

26.Castell LM, et al. Does glutamine have a role in reducing infections in athletes? Eur J Appl Physiol 1996;73(5):488-90.

 

 

  • MAGNESIUM This mineral is involved in adenosine triphosphate (ATP) production from fatty acid oxidation, post-contractile muscular relaxation, and bone remineralization. It is also involved in phosphatidylglycerol (DPG) production, which is important to red blood cell formation. ATP, present in all cells but particularly in muscle cells, stores energy. Low magnesium levels can acutely contribute to early fatigue, nausea and muscle cramps. Chronic magnesium deficiencies can lead to increased osteoporosis risk and anemia.6

Athletes lose magnesium through sweat and urine. This, combined with the fact that athletes' diets are usually low in magnesium, generally leads to the need for supplementation.7 Recommended intake for endurance athletes is 500 to 800 mg daily.8 Higher doses can cause diarrhea.

 

  • POTASSIUM This mineral, present in intracellular fluid, is responsible for regulating total body water and stabilizing controlled and automatic muscle contractions. It is also lost through sweat and urine.

In a study of athletes running 40 minutes at 70 degrees Fahrenheit, potassium loss was estimated at 435 mg/hour. The rate of potassium loss is approximately 200 mg/kg of weight lost during exercise.9

Cells release potassium into the bloodstream and serum levels rise with exercise, possibly instigating fatigue. Potassium supplementation after short events (less than two hours), and during and after long events, is warranted.10 For postactivity replacement, athletes should take about 435 mg/hour of exercise or 200 mg/kg of weight loss. As much as 150 mg/hour during activity can be tolerated by most athletes. Supplement potassium cautiously because too much too quickly can cause cardiac arrest.

Supplementing with potassium during training does increase markers of recovery, primarily serum lactate and muscle hydration, but does not aid performance.10

 

  • SELENIUM Essential to antioxidant glutathione peroxidase (SeGPx) production, selenium is a free radical-scavenging tripeptide made up of glutamine, cysteine and glycine. It is concentrated in the lining of the GI tract and lungs, in the liver, and in skeletal muscle. In an animal study, reducing muscular SeGPx increased cellular damage from prolonged exercise, supporting the theory that free radical-induced muscle damage causes muscle fatigue.11

Research shows selenium benefits athletes' immune function and helps repair cellular damage. Researchers studied the selenium supplementation effects on muscle SeGPx in 24 healthy nonsmoking males. Half took 240 mcg of sodium selenite; half took placebo. After cycling to exhaustion—durations ranged from 2.6 to 3.5 hours—the group that took selenium showed less cellular damage.12

Supplementation with 200 mcg of selenium is safe and warranted for endurance athletes.13

 

  • SODIUM This element helps cells retain water and prevents dehydration. Sodium also enables ATP generation. For events lasting longer than five hours, especially in hot weather, hyponatremia (dangerously low sodium) is a real concern. This especially applies to first-time or slower-running marathoners. Most organized events have aid stations with salty snacks. Anyone out for more than a few hours, especially on a warm day, should make sure to get some salt from snacks and fluid-replacement drinks.

A prospective study was performed on 36 athletes during a three- to four-hour triathlon and 64 athletes at an ironman race, which lasts between nine and 15 hours. No athletes were hyponatremic after the shorter race, but 27 percent were hyponatremic following the ironman. An average of 17 percent of the ironman participants required medical attention, most for hyponatremia.14

Extrapolated from that study, athletes should aim for 80 to 100 mg sodium per quart of hydrating beverage and 100 to 300 mg sodium per hour from other sources.

 

  • ZINC This mineral aids in post-exertion tissue repair and in the conversion of food to fuel. Both male and female athletes have lower serum zinc levels compared with sedentary individuals. Studies correlate endurance exercise with periods of compromised immunity—zinc depletion may be one reason.15

Those who train without days off lose zinc even more quickly. In a study of cyclists, researchers looked at zinc excretion via sweat. Half of the group underwent intense training for two months. Half underwent moderate training with two to three days off per week. Both groups were studied before and after. The exercising group showed increased zinc excretion while the control group showed no increase.16 The researchers believe altered zinc metabolism coupled with increased zinc excretion and stress levels lead to fatigue and decreased endurance.

Athletes should take 30 to 60 mg zinc daily.17 Zinc picolinate or monomethionate are most easily tolerated.18

Prevent Oxidative Damage
Antioxidants are another set of nutrients that endurance athletes are wise to use.

 

  • VITAMIN E For athletes, one of the most important antioxidants is vitamin E. Aerobic athletes may have an increased need for this vitamin because their cells undergo more oxidative damage. Research shows athletes have less cellular damage when they ingest more vitamin E.19 Aerobic exercise places additional demands on the molecular free radical scavengers of the body, and vitamin E is a well-known scavenger.

In a study of 30 top-class cyclists, five months of supplementation with natural vitamin E (alpha-tocopherol) at an 800-IU daily dose significantly decreased markers of oxidative damage to muscle tissue. However, vitamin E did not benefit athletic performance.

Studies evaluating vitamin E as an ergogenic, or performance aid, show no benefit.19 One possible exception is at higher altitudes where oxidative stress is more intense. A group of six mountain climbers took 400 mg synthetic vitamin E (dl-alpha-tocopherol acetate). During exertion at altitude, they showed less output of pentane and lactic acid—both markers of oxidative damage, but not suggestive of improved athletic performance. The athletes also showed a statistically significant increase in anaerobic threshold compared to a placebo group.20

The amount of vitamin E necessary to benefit athletes is not obtainable through diet. The jury is still out on natural vs. synthetic vitamin E, but endurance athletes should take 400 to 800 IU/day.

Protein and Glutamine
Without adequate protein and glutamine, athletes can feel the effects of reduced metabolism, poorer recovery times and increased susceptibility to infections.

 

  • PROTEIN The RDA for protein is 60 mg per day for adults (specifically 0.8 g/kg of body weight/day). This recommendation, however, is based on the needs of sedentary individuals. Recent studies indicate that protein needs increase during strenuous activity, which applies to both strength and endurance athletes.21

Endurance athletes need more protein for different reasons than strength athletes do. Endurance athletes primarily use protein for maintaining aerobic metabolism, compared with the increased tissue-repair needs of strength athletes. When intake is inadequate, the body sequesters the needed proteins from lean tissue, which gives overtrained endurance athletes a gaunt appearance. A protein deficit also impairs an athlete's recovery and wound-healing ability.14

Researchers recommend endurance athletes eat 1.2 to 1.4 g/kg of body weight/day of protein.22 For a 155-pound athlete, this means a total of 85 to 100 g protein per day. Only a few studies recommend protein intake levels as high as 2 g/kg of body weight/day.23

 

  • GLUTAMINE This amino acid increases the numbers of lymphocytes and macrophages. When glutamine levels are low these immune cells show depressed activity.24 Prolonged exercise consistently lowers glutamine levels. Glutamine supplementation reduces vulnerability to infections after prolonged exercise, though a few studies examining this phenomenon at lower exercise intensity levels have not shown benefit.25

Oral glutamine replacement after exercise can lower infection risk. In one study, 200 runners and rowers were given placebo or 2,000 mg glutamine two hours after exercise. In the seven days following the exercise, 81 percent of the glutamine-supplemented group were infection-free compared to 49 percent in the placebo group.26

A supplement that provides 2 g glutamine daily is a wise choice for athletes in training.26

Athletes who train strenuously for competition have greater nutritional needs than sedentary people. Adequate nutrients can mean quicker recovery time, lower infection rates, less fatigue, and ultimately, can help athletes reach their desired performance levels.

 

Alan Christianson, N.D., has a naturopathic private practice in Scottsdale, Ariz.

References

1. Guezennec CY, et al. Is there a relationship between physical activity and dietary calcium intake? A survey in 10,373 young French subjects. Med Sci Sports Exerc 1998 May;30(5):732-9.

2. Voss LA, et al. Exercise-induced loss of bone density in athletes. J Am Acad Orthop Surg 1998 Nov-Dec;6(6):349-57.

3. Bennell KL, et al. Effect of altered reproductive function and lowered testosterone levels on bone density in male endurance athletes. Br J Sports Med 1996 Sep;30(3):205-8.

4. Eichner ER. Sports anemia, iron supplements, and blood doping. Med Sci Sports Exerc 1992 Sep;24(9 Suppl):S315-8.

5. Weaver CM, et al. Exercise and iron status. J Nutr 1992 Mar;122(3 Suppl):782-7.

6. Altura BM, et al. Magnesium depletion impairs myocardial carbohydrate and lipid metabolism and cardiac bioenergetics and raises myocardial calcium content in-vivo: relationship to etiology of cardiac diseases. Biochem Mol Biol Int 1996 Dec;40(6):1183-90.

7. Lukaski HC, et al. Micronutrients (magnesium, zinc, and copper): are mineral supplements needed for athletes? Int J Sport Nutr, 1995;5 Suppl:S74-83.

8. Seelig M. Magnesium deficiency in the pathogenesis of disease. New York: Plenum Press; 1980.

9. Wenk C, et al. Methodological studies of the estimation of loss of sodium, potassium, calcium and magnesium through the skin during a 10 km run. Z Ernahrungswiss 1993 Dec;(4):301-7.

10. Tarnopolsky MA, et al. Mixed carbohydrate supplementation increases carbohydrate oxidation and endurance exercise performance and attenuates potassium accumulation. Int J Sport Nutr 1996 Dec;(4):323-36.

11. Venditti P. Effect of training on antioxidant capacity, tissue damage, and endurance of adult male rats. Int J Sports Med 1997 Oct;18(7):497-502.

12. Tessier F, et al. Muscle GSH-Px activity after prolonged exercise, training, and selenium supplementation. Biol Trace Elem Res, 1995 Jan-Mar;47(1-3):279-85.

13. Persson-Moschos M, et al. Plasma selenoprotein P levels of healthy males in different selenium status after oral supplementation with different forms of selenium. Eur J Clin Nutr 1998 May;52(5):363-7.

14. Hiller WD, et al. Medical and physiological considerations in triathlons. Am J Sports Med 1987 Mar;(2):164-7.

15. Cordova A. Behaviour of zinc in physical exercise: a special reference to immunity and fatigue. Neurosci Biobehav Rev 1995 Fall;19(3):439-45.

16. Cordova A, et al. Effect of training on zinc metabolism: changes in serum and sweat zinc concentrations in sportsmen. Ann Nutr Metab 1998;42(5):274-82.

17. Barrie SA, et al. Comparative absorption of zinc picolinate, zinc citrate and zinc gluconate in humans. Agents Actions 1987;21(1-2):223-8.

18. Rohde T, et al. Effect of glutamine supplementation on changes in the immune system induced by repeated exercise. Med Sci Sports Exerc 1998 Jun;30(6):856-62.

19. Rokitzki L, et al. Alpha-tocopherol supplementation in racing cyclists during extreme endurance training. Int J Sport Nutr 1994 Sep;4(3):253-64.

20. Simon-Schnass I, et al. Influence of vitamin E on physical performance. Int J Vitam Nutr Res 1988;58(1):49-54.

21. Lemon PW, et al. Do athletes need more dietary protein and amino acids? Int J Sport Nutr 1995 Jun;5 Suppl:S39-61.

22. Shephard, RJ, et al. Immunological hazards from nutritional imbalance in athletes. Exerc Immunol Rev 1998;4:22-48.

23. Rohde T, et al. The immune system and serum glutamine during a triathlon. Eur J Appl Physiol 1996;74(5):428-34.

24. Newsholme EA, et al. The proposed role of glutamine in some cells of the immune system and speculative consequences for the whole animal. Nutrition 1997 Jul-Aug; 13(7-8):728-30.

25.Rohde T, et al. Effect of glutamine supplementation on changes in the immune system induced by repeated exercise. Med Sci Sports Exerc 1998 Jun;30(6):856-62.

26.Castell LM, et al. Does glutamine have a role in reducing infections in athletes? Eur J Appl Physiol 1996;73(5):488-90.

 

runners diet s 10 for the Road: Essential Nutrients for Endurance Athletes

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Creatine Supplement

May 19, 2009 
Filed under Diet And Nutrition

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Creatine is an amino acid. It is normally produced in the body from arginine, glycine and methionine. Creatine plays a vital role in cellular energy production as creatine phosphate (phosphocreatine) in regenerating adenosine triphosphate (ATP) in skeletal muscle. Without ATP, muscle contraction is not possible. Oral administration of creatine increases muscle stores and may increase muscle strength and improve exercise performance. In the diet, creatine is found in meat and fish – although cooking destroys most of it.

Claims:

1. Increased energy

2. Enhances muscle size and strength

3. Increased power output

Theory:

Most of the creatine in the diet comes from meat (an 8-ounce steak might have a gram), but about half of the body’s supply is manufactured in the liver and kidneys. On average, your muscles require about 2 grams of creatine a day (somewhat more for muscular people, a bit less for skinny folks), but more or less depending on your activity level and degree of muscle mass.

Creatine is stored in muscle cells as phosphocreatine and is used to help generate cellular energy for muscle contractions. It also may increase the amount of water that each muscle cell holds – thus increasing the size of the muscle (and possibly its function as well). Creatine is used in the body to produce creatine phosphate or CP, which can be thought of as a storage form of quick energy. The function of CP is to regenerate the primary supply of cellular energy – which comes from adenosine triphosphate (ATP). ATP supplies energy for all cells in your body. Upon giving up some of its energy, ATP becomes ADP (diphosphate) and needs to be regenerated back to ATP to do it all over again. CP performs this crucial ATP regeneration step by donating a phosphate group to ADP.

Under conditions where rapid resynthesis of ATP is important – such as during repeated bouts of high intensity exercise – a higher muscle concentration of CP may serve as a reservoir of stored energy and, therefore, enhance performance. Although it has not been studied extensively, there may also be a role for creatine in maintaining muscle mass and preventing the muscle wasting that occurs as a result of old age and in chronic conditions such as AIDS and heart failure.

Safety:

Because of its effects on muscle strength and size, creatine is often confused with anabolic steroids. Steroids, which mimic the effects of the male sex hormone testosterone, can result in a wide variety of adverse side effects such as acne, hair loss, testicular shrinkage and psychological problems. Although the long-term effects of prolonged creatine use has not been examined, no obvious adverse effects have been linked to use of creatine as a dietary supplement. Side effects reported anecdotally include gastrointestinal distress, nausea, dehydration and muscle cramping – but none of these effects have been documented in scientific studies. Although no serious side effects have been scientifically verified in subjects using relatively brief (less than 4 weeks) creatine regimens, there are anecdotal reports of muscle cramping associated with the creatine supplements. Some athletes have reported muscle cramps, muscle tears and dehydration. A cautionary note is also advised, for people with kidney disorders and for those at risk for dehydration (such as exercise in extreme heat or during cutting weight for wrestling or lightweight crew).

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