Julie Moss competing in the 1982 Hawaii Ironman Triathlon
October 23, 2009
Filed under Triathlon Videos
In 1982, Julie Moss became worldwide famous during the Hawaii Ironman Triathlon, in which she competed as part of her research for her exercise physiology thesis. At approximately two miles before the finish line, she came severely dehydrated. She staggered and crawled towards the end of the course, only to be passed moments before the finish line by Kathleen McCartney. Her struggle to finish the Ironman was broadcasted live around the world by ABC Sports, and provided inspiration to many….
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Can You Smoke and Still Run Marathons?
August 17, 2009
Filed under Running
Smoking does not affect running. Yea, right, and neither does 15 pounds of excess body fat, dehydration, or a two month lay-off.
Anyone who has been to a marathon on Okinawa has witnessed a few of the die-hard locals smoking cigarettes before and after their race, but they are usually part of that group just out for the day trying to finish. They feel they can smoke and still go slow for a long time. Maybe even beat the time they put up last year.
Inhaling smoke from tobacco does many things to the body that significantly compromises airway and blood flow, severely limiting the ability run fast and race to your potential. For example:
Smoking a cigarette immediately increases carbon monoxide in your blood. Instead of floating around harmlessly, carbon monoxide poison latches onto hemo-globin, the molecule responsible for transporting oxygen from your lungs to your muscles. This means less oxygen is getting delivered to your muscles during exercise, resulting in early fatigue and oxygen debt.
According to Australian sports physiologist David Pyne, inhaled smoke causes an immediate 2-3 fold increase of resistance inside the airways of the lungs. One primary cause of this resistance is chronic swelling of the mucous membranes due to constant smoke-related irritation.
Over time, another factor that will slow you down is the accumulation of tar. A pack a day smoker inhales about 2 cups a year, so it does not take long for air exchange to become compromised in the lungs. In effect smokers end up with a smaller lung surface area than non-smokers.
Along with maximal oxygen consumption, lactate threshold is much lower in smokers compared to non-smokers. Lactate threshold is that running speed when lactic acid begins to accumulate in the blood, a sure sign that your muscles are not getting enough oxygen to meet the demand. Anyone who runs knows that the earlier you have to start breathing hard, the sooner you must slow down.
Nicotine in tobacco causes blood vessels to constrict, decreasing blood flow to muscle while increasing in blood pressure and heart rate. The heart of a smoker therefore has to work harder than a nonsmoker in order to deliver the same amount of oxygen to the muscles.
Smoking increases the amount of plaque deposited in the arteries. Eventually vessels become narrower and less elastic, with blood flow eventually becoming restricted. Once this happens, endurance is permanently reduced.
Smokers produce more phlegm and often have irritation of the entire respiratory track, making breathing during fast running very difficult.
All of these factors make running more of a chore for smokers. Sure, some smokers are blessed with the ability to run, but the truth is they would feel a whole lot better and run much faster if they quit. Smokers will never run fast relative to their potential, and as long as they continue the habit you can bet they will progressively get slower.
Some smokers may be able to run, and some runners may be able to smoke, but neither will ever be able to win.
10 for the Road: Essential Nutrients for Endurance Athletes
August 12, 2009
Filed under Crossfit, Diet And Nutrition, Running, Triathlon
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.
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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.
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
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
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.
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
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
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
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.
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.
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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.
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
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
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.
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
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
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
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.
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.
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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.
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
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
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.
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
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
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
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.
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.
|
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.
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
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
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.
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
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
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
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.
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.
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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.
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
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
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.
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
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
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
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.
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.
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Nutrition for Young Runners
August 9, 2009
Filed under Childrens Health, Diet And Nutrition, Running
Running is a popular sport with children and adolescents around the world.
Depending on the age and calibre of the young athlete, training may range from the weekly school Physical Education lesson to structured sessions at a local club or to participation in one of the special training plans on The World Keeps Running.
The goals of training may range from simply having fun, to improving fitness and physique, to developing running skills and preparing for an event.
For the youngest age groups, there should be no special need for any change to diet. The main aims are to minimise the risk of gastrointestinal upset and to avoid problems of dehydration on hot days. It may be best to avoid solid food for two to three hours before training and particularly an event as the combination of exercise and nerves can cause some gastric distress.
Children can often be out in the sun for many hours on sports days, and adults should be vigilant to ensure frequent application of sun cream and to be aware of any child who seems to be having problems. Ample fluid should be available, and children may need to be reminded to take small amounts of drinks at regular intervals.
The physiology of children and adolescents differs from that of adults in several ways. The mechanisms of thermoregulation are less efficient in children, and special attention must be paid to the environment, activity patterns, clothing and hydration to avoid problems of hyperthermia or hypothermia.
The growth spurts during childhood and adolescence require nutritional support in terms of adequate intake of energy, protein and minerals.
Active young people may find it difficult to meet their needs for energy and nutrients when the costs of training and growth are added. Young people may not have developed the nutritional knowledge and time management skills to fit in all the eating occasions required to achieve high energy, nutrient-rich eating.
The rate of obesity in children is still rising, but active youngsters do need a plentiful supply of energy from foods and energy-containing drinks.
Young athletes eating a wide range of foods should not need to use dietary supplements, and athletes and coaches should be aware that these do not provide a short cut to success.
Encourage children to become involved in menu planning for the family meals, and for special needs associated with their training and competition sessions. Encourage positive messages that good eating practices, involving good choices of foods and drinks, are part of the formula for sporting success, and a healthy life.
Children often need snacks to meet their energy needs over the day, and the special needs of recovery from sport. These snacks should involve nutrient-rich choices such as fruit, sandwiches, dried fruit and nuts, flavoured dairy products, and cereals and milk. Some planning is needed to have these choices on hand over the day, and before or after sport.
What about Caffeine and Athletes
August 5, 2009
Filed under Diet And Nutrition
By Stephanie Nunes, RD
There is much confusion on the health effects of caffeine. I am going to address specific topics that may be of interest to athletes: Dehydration, Bone Health, Sports Performance, Cancer, and Heart Disease.
Extensive research has been conducted on the health effects and safety of caffeine consumption and the general consensus appears to be that moderate caffeine consumption (approximately 300mg/day) is safe. It is estimated that the average daily caffeine consumption among Americans is 280mg/day.
|
A Few Common Sources of Caffeine |
|
| Source | Caffeine |
| 8 oz Brewed Coffee | 135 mg |
| 1 oz Expresso | 30-50 mg |
| 8 oz Green Tea | 25-40 mg |
| 8 oz Black Tea | 40-70 mg |
| 12 oz Coca-Cola | 34.5 mg |
| 12 oz Diet Coke | 46.5 mg |
| 12 oz Mountain dew | 55.5 mg |
| SoBe No Fear | 158 mg |
| 1.45 oz Sweet chocolate bar | 27 mg |
| Exedrin | 65 mg |
Dehydration
Researchers used to believe that caffeinated beverages had a diuretic effect and caused dehydration. Recent research now shows that coffee, tea, and other caffeine-containing beverages do not affect hydration status on those who are already accustomed to consuming caffeine. Caffeine only has a diuretic effect if you consume large amounts of it (500-600 mg/day).
My advice: Enjoy your favorite caffeinated beverage while continuing to focus on maintaining proper hydration with fluids such as water, juices, sports drinks, etc.
Bone Health Research has shown that caffeine is not a significant risk factor for poor bone health when adequate calcium is consumed.
My Advice: Include at least 2 servings of calcium rich foods daily and add milk to your coffee or tea (my favorite is a non-fat mocha!)
Sports Performance
Early researchers thought caffeine's benefit on sports performance was linked to its ability to spare muscle glycogen and increase fatty acid metabolism. Now the current thinking is that the positive effects of caffeine have more to do with "mental energy". Studies on sports performance have shown that caffeine had a 24% improvement in endurance performance and 4% improvement in strength performance. The quantity used which showed the biggest improvement was 6 mg/kg body weight. Less than 3 mg/kg showed a smaller improvement or no improvement at all. It is also thought by some that the amount of caffeine needed for sports performance depends partly on "caffeine sensitivity".
Additional Note: Substances in coffee and tea can interfere with iron absorption.
My Advice: If you suffer from anemia, do not drink tea or coffee with your meals or within one hour after. The best advice would be to drink them an hour before eating. If you don't usually use caffeine but want to try it for sports performance, watch for stomach distress.
Cancer
The American Institute for Cancer Research (AICR) recently released an article, "The Truth about Caffeine and Cancer". The AICR stated that coffee is no longer associated with increased cancer risk. In fact, "because it contains antioxidants and anti-inflammatory compounds, coffee may actually boost health and possibly reduce cancer risk." Tea continues to show cancer combating benefits, especially green tea.
Heart Disease
Recent research has shown no relationship between caffeine ingestion and heart disease. However, there can be exceptions to this rule in that some may react differently to caffeine than others.
My Advice: Check with your physician if you are experiencing elevated blood pressure or arrhythmias.
Summary:
Caffeine beverages can be worked into an athletes meal plan as long as you pay attention to overall daily hydration, continue to eat/drink the recommended calcium products, and follow an overall balanced meal plan that meets your sports- specific nutrient needs.
Stephanie Nunes is a Registered Dietitian and runner residing in San Luis Obispo, California. Her private practice is "Rock Solid Nutrition" and she provides individual counseling, on-line counseling, lectures or presentations for specific groups, and nutrition related articles. If you would like to contact Stephanie for any of these services, her e-mail address is Rocksolidnutrition@sbcglobal.net.
Why Is Exercise Important?
August 2, 2009
Filed under Fitness
We all know we are supposed to exercise but we make excuses not to do it. However, why is exercise so important? Well exercising helps prevent diseases. It reduces the risk for heart disease, cancer, high blood pressure and diabetes. It can even improve your stamina and delay the aging process. That is good news for us women. We never want to age! Exercising makes, your heart and lungs work better so that daily activities become easier. Things like carrying those heavy groceries, playing with your kids and more. Not to mention regular exercise makes you feel better about yourself. I used to exercise everyday and I did indeed feel good and had more energy. There are three types of exercise Aerobic, Anaerobic, Stretching.
You do not have to do anything too strenuous at first. Take a walk; use the stairs instead of the escalator. Even these small steps can make a big difference. If you are trying to lose weight start small and make sure you eat a well balanced diet. Try cooking at home instead of those fat filled take out dinners. Exercise can also benefit your sleep patterns and make it easier to fall asleep and stay asleep. Also making sure you drink plenty of water can actually help you lose weight. I know from experience that this works. I drink a lot of water and a few years ago, it helped me to feel full and lose weight faster. Make sure to drink plenty of water when exercising to avoid dehydration.
Everyone should exercise including children, adults and the elderly. Children need to exercise to grow and develop strong bones. Far too many children are obese. As well, there are adults who are obese. This can lead to horrible health conditions. People need to realize that exercise is the fastest way to lose that weight. You should do some form of exercise a few times a week. Just do whatever you like, swimming, running, walking etc. It will make your body stronger, fitter and more flexible. Just remember to warm up with stretching exercises and then have a cooling down period the same way. Otherwise, you could end up with an injury. No one wants an injury when you are exercising.
Exercise also removes toxins and waste from the body. Without exercise they are stored as fat in the body. That is where water comes in to help flush these toxins from your body. In fact, for optimal health you should be expelling waste a few times a day. However, how many of us actually go to the washroom that often? No wonder we have problems! In this world of immediate satisfaction, we are told to reward ourselves with food. This is the wrong message for some people who are battling weight issues. We all need to get up from our seats, stretch, and move and buy something other then those sweet treats! Wouldn’t you rather be muscle toned, slim, and fit into those jeans then overweight and tired and flabby and have nothing to wear?
Recovery strategies to enhance performance and reduce injury
July 29, 2009
Filed under Diet And Nutrition, Outdoors Activities
| By Shawn Talbot, PhD. | ||
| In the realm of elite sport, scientists, coaches and athletes are aware that a hallmark of top-level athletic performance is an outstanding ability to recover from intense workouts and competition. And understanding how nutrition is linked to recovery is essential. For trail runners, full recovery after a big day pounding the dirt is often the difference between staying healthy and injury free or being stuck indoors due to illness or chronic pain.
The Downside to a Good Workout An ideal recovery strategy involves immediately replacing what your body lost during exercise through proper recovery nutrition. Nutritional Recovery Triad Since it can be difficult to drink enough during long, intense sessions, assume your body is dehydrated post-run and drink more than your thirst demands. Electrolyte beverages with a low sugar concentration are superior to water in the body’s ability to absorb and retain the fluid. Despite the wide variety of bars, gels and beverages, the bottom line is to select something that tastes good and your stomach can tolerate. A post-exercise snack immediately replaces the sugar stores burned off during exercise. Consuming carbohydrates and protein in liquid form (such as one-percent chocolate milk) is a convenient way to refuel and rehydrate simultaneously. As a rule of thumb, consume around 300 to 500 carbohydrate calories as soon as possible following exercise. Great snacks are banana with yogurt, a handful of nuts and an apple or a bowl of whole-grain cereal topped with berries and one-percent milk. Wash down solid food with plenty of water or sports drink. While rehydration and glycogen replacement replaces what your body lost, biochemical balancing restores the body’s chemistry to normal levels. Exercise-induced inflammation and oxidation damages muscles, lung tissue and temporarily suppresses the immune system. Until you have rested, you are at increased risk of colds, flu and other respiratory tract infections, injuries such as tendonitis, strains, stress fractures and overtraining which characterized by lethargy, depression and general moodiness. Anti-oxidant-rich berries (blueberries, blackberries and raspberries), most fruit juices (orange, grape, and apple) and dietary supplements containing flavonoids and inflammation-reducing enzymes help repair tissues. Foods containing these nutrients are pineapple and papaya, roasted soy nuts and other soy products containing immune-balancing beta-sitosterol. Powerful Protein Protein is made up of amino acids and is essential for rebuilding damaged muscle tissue and restoring immune system function. Protein-packed foods, such as milk or yogurt (non low-fat varieties) or a palm-sized portion of beef, poultry, fish or legumes (beans), provide amino-acid building blocks for tissue repair. The immune system uses proteins made up of glutamine and the three branched chain amino acids (BCAA) as fuel. Whey protein, found in some post-exercise recovery drinks and dairy products, is a decent source of all four essential amino acids, but some studies suggest that amino acid uptake is faster when consumed as isolated nutrients in the form of dietary supplements. Look for products that deliver effective levels of BCAAs (1500mg) and glutamine (1000mg) in the proper ratios for post-exercise immune system support. Don’t fall for the "more is better" gimmick, but instead look for products that back up their formulations with research studies on runners. All protein-containing foods will have some BCAAs and glutamine, but dairy products (because of their whey component) are a particularly good food source. Recovery-enhancing nutrition may be the most reliable method to improve your trail running. Don’t just eat something after coming off the trail; instead, give some thought to "functional eating." When to Eat What Evening Post-Workout Meal Over the Next Week Before the Next Big Outing Shawn Talbott holds a PhD in nutritional biochemistry and MS in Exercise Science, and practices recovery principles after his trail runs in Utah’s Wasatch Mountains. He can be reached at smtalbott@supplementwatch.com. |
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20 Tips to Stay Cool on a Summer Run
July 14, 2009
Filed under Running
I live in Atlanta, so I know all about running in the heat. And you know what? It’s not so bad. In fact, if you’re smart about it and make some adjustments, summer is a great time of year for running. Even in the muggy South.
And I’m not the only one who thinks this way. You should see how crowded the streets and trails get here in the summertime, especially in the mornings. Which leads me to my first of 20 tips to make summer running fun.
1. Try Running Early in the Morning.
It’s the coolest, most serene part of the day, and there’s nothing like a morning run to boost your mood all day long.
2. Run Whenever.
Maybe the morning doesn’t work for you. Fine. The long daylight hours make for lots of other options. Meet with a group several evenings each week and save lunchtime for solo runs. Maybe an occasional morning run wouldn’t be so awful. Try it and see. Running in winter is more confining simply because there’s so little daylight time. Not so in summer.
3. Drink Like Crazy.
Even if you don’t feel thirsty, drink at least 8 oz. of fluid each hour, and more if you’re outside or tend to perspire a lot. You’ll run better with adequate fluid intake, and you’ll feel better, too. By keeping your water storage high, you’ll also improve your body’s cooling mechanisms.
4. Acclimate With Care.
You need to acclimate to the heat in a safe and gradual manner, not haphazardly. For the first two weeks of hot weather, do no speed sessions and keep your midday running bouts to 30 easy minutes at most. (You can go longer on cool mornings or evenings.) In 10 days to two weeks, you should be fully acclimated.
5. Go Light and Loose.
Wear light-colored, loose-fitting clothing. The former will reflect the sun’s rays better; the latter will enable you to take advantage of any breeze, including the one you make by running. The new sports-specific synthetics are better than cotton, too. They stay drier and wick moisture better than natural fibers do.
6. Screen it Out.
To protect yourself from skin cancer and other skin damage, use sunscreen liberally. Do so even on partly cloudy days; harmful ultraviolet rays are not blocked by cloud cover. Another benefit: Sunscreen can decrease your skin and body temperatures, so you’ll stay cooler during exercise.
7. Join a Running Club.
This is a good tip year-round, but running clubs are especially active in summer. Long group runs on the weekend, evening speed sessions during the week, social nights. You’ll love the energy and camaraderie of a running club.
8. Maximize Head Room.
You lose a major portion of body heat through your head, which is bad in winter but good in summer. So on hot days, don’t cover your noggin tightly with a hat. Cover it, for sure, but with a loose-fitting hat, preferably made of mesh or some other breathable material.
9. Pour it on.
There’s nothing like the psychological relief of pouring cold water over your head on a hot run. But don’t depend on it to keep your body temperature down, because it won’t. To help you do that, you need to drink the water.
10. Go Out and About.
Once every couple of weeks, schedule a run at a nearby park, nature trail or historical park. Bring the family along or go with a running friend or two. Take a picnic with you for after the run, then do some sightseeing.
11. Start Slowly.
I’m a big proponent of doing this in all seasons, but starting your run slowly is particularly beneficial on hot days. The slower you start, the longer you’ll keep your body heat from reaching the misery threshold. If you normally run at an eight-minute mile pace, for example, do your first mile at a 10-minute pace.
12. Head for Water.
Running near water—whether it’s along a river, lake or ocean—is usually cooler and breezier. Urban streams often have paths running alongside of them, if you take the time to explore. And even if the air temperature is about the same, you’ll likely feel cooler just being near water.
13. End With a Dunk.
There is absolutely no better place to start a run than at a pool. Why? Because when you finish your run there, you can take a refreshing dip. Once a week or so this summer, bring your bathing suit and running gear to the pool.
14. Run Fountain-to-fountain.
As a fallback for those beastly hot days, design a run that takes in frequent water stops. Water fountains are the obvious choices, but there are many more possibilities. When you map out your route, consider gas stations, health clubs, hospitals, schools, convenience stores and city parks.
15. Make Like a Camel.
Especially on long runs or trail runs where you’ll be away from water sources, bring your own. Use a water belt, pouch or holster for bottles or simply carry it (you’ll get used to it). Another option: The night before your long Sunday run, take your bike or car out and stash several bottles along your next day’s running route.
16. Heed the Heat Warnings.
You need to be very sensitive to the warning signs of heat illness, which, if it progresses, can be fatal. If you feel trouble coming on, you need to stop running, find some shade, get liquids and then find a ride or walk home. Following are signs of impending heat illness:
- Headache or intense heat buildup in the head.
- Confusion or lack of concentration.
- Loss of muscular control.
- Oversweating followed by clammy skin and cessation of sweating.
- Hot and cold flashes.
- Upset stomach, muscle cramps, vomiting, dizziness.
17. Decrease the Speed.
Do your speed training in the morning or evening. Otherwise, you’re really going to put a strain on your system. The heart literally beats faster in high heat, as it’s pumping extra blood out to the skin as part of the body’s evaporation/cooling mechanism. You won’t be able to run as fast, so don’t try to.
18. Lower Your Expectations.
In training and in races, you won’t be able to run as fast as you would on cool days. If race day comes, and it’s super hot that morning, ease back and treat it as a training run — and drink at all the water stops.
19. Watch What You Drink.
Both caffeine and alcohol are diuretics, which means they increase urine output. This puts you at greater risk of dehydration. Since hot weather is already causing you to dehydrate faster, be especially careful about your caffeine and alcohol intake in summer. People in my part of the country drink a lot of iced tea. Be careful if you do, as iced tea contains a significant amount of caffeine. An alternative: herbal iced tea.
20. Bag it if it’s too Hot.
Some days are going to be unsafe for running, especially if you live in an urban area where air pollution is also a concern. On those occasions, consider skipping running altogether. Or run inside on a treadmill. Or hit the pool for some laps.
Sure, it’s going to be hot this summer. No way around that. But with some planning and a little imagination, you can minimize the downside and make it work for you. Stay flexible, have fun and, above all, be safe.
Are You Ready to Run?
July 14, 2009
Filed under Running
By John Hanc
According to William Roberts, M.D., medical director of the Twin Cities Marathon in Minneapolis-St. Paul, ambient temperature is only a small factor in predicting heat stress. "At Twin Cities, we’ve had cases of heatstroke at 50 degrees," he says. "And there have been marathons in Rio de Janeiro without any problems. So much depends on your acclimatization levels."
Dr. Roberts has researched cases of fatal heatstroke among athletes and found that the runner’s general health and use of medications were contributing factors, just as important as dehydration and weather conditions. He offers this checklist to determine if you’re ready to run in the heat. If you answer "no" to any of questions 1 through 6 or "yes" to question 7, Dr. Roberts advises either exercising indoors or keeping your run very short and very easy.
1. Are you acclimatized—have you been in similar temperatures during the last two weeks?
2. Are you well rested (having gotten at least seven hours of sleep last night), and have you been in cooled/air-conditioned environments for some part of the last 24 hours?
3. Are you hydrated? (If you are hydrated, your urine will be pale yellow in color. If it is dark like apple juice, you’re dehydrated.)
4. Are you healthy—no recent illnesses?
5. Are you well nourished?
6. Have you avoided alcohol in the last 24 hours?
7. Are you taking medications with ephedrine or other prescription medicines that might interfere with your thermal regulation (information you can find in the literature that comes with the medication or get from a pharmacist)?
South Beach Diet
May 23, 2009
Filed under Diet And Nutrition
Definition
The South Beach diet is a three-phase, carbohydrate-restrictive diet. It emphasizes foods that are low on the glycemic index (GI) and low in saturated fat, such as lean meats, vegetables, cheeses, nuts, and eggs. Unlike other carbohydrate-restrictive diets, such as the Atkins and Zone diets, the South Beach diet promotes "good" carbohydrates, such as whole grains and fruit.
Origins
The creator of the South Beach diet, Dr. Arthur Agatston, is considered a leading cardiologist and is the director of the Mount Sinai Cardiac Prevention Center in Miami Beach. Originally, he had intended to design an eating plan to improve the cholesterol and insulin levels of his patients. However, Dr. Agatston soon discovered that his patients also lost weight on his plan. After further research, he approached Marie Almon, R.D., chief clinical dietician at the hospital, to help develop the eating plan into an effective diet. The results became the South Beach diet. Having sold more than a million copies since its publication in April 2003, The South Beach Diet book has remained on the New York Times bestseller list for over a year.
Benefits
The primary benefit of the South Beach diet is considered by many to be its initial rapid and significant weight loss—8–13 lb (4–6 kg) in the first two weeks. After the first two weeks, weight loss continues at a slower rate, averaging 1–2 lb (0.4–1 kg) weekly. In addition to weight loss, the diet reduces cholesterol and insulin levels, thus reducing the risks of diabetes and heart disease. It is claimed that the diet is easy to follow because it is designed to eliminate cravings and has more flexible food options after the first two weeks.
Description
In his book, The South Beach Diet, Dr. Agatston states that "this diet is not low-carb. Nor is it low-fat." Instead, the diet focuses on eating the "good" carbohydrates (fruits, vegetables, and whole grains) and "good" fats (olive oil and nuts) rather than eliminating them from the diet entirely.
Dr. Agatston based the core of his dietary plan around the glycemic index –the increase in blood sugar levels by foods containing carbohydrates during a set amount of time.
After consumption, food is metabolized into sugars and promotes the release of the hormone insulin. When the blood contains excess sugar, insulin removes it from the blood stream by storing it in cells, including fat cells. High-glycemic carbohydrates (greater than 70 GI) are metabolized rapidly, which causes elevated insulin production. High levels of insulin result in more blood sugar being stored as fat, thus causing weight gain. This pattern induces craving for more carbohydrates, thus leading to the consumption of more high-GI foods. Low to moderate-GI foods, however, raise insulin levels more slowly and sugars are metabolized more effectively, thus reducing the amount of blood sugar stored as fat. Cravings for more food is reduced. In addition, by eating these low-GI foods, the risk of insulin resistance that can lead to atherosclerosis and diabetes is reduced. As such, Dr. Agatston designed the South Beach diet to promote foods low on the GI and eliminate the body’s craving for high-GI foods.
The South Beach diet consists of three phases. Phase one is the strictest part of the diet and lasts for two weeks. The purpose of Phase one is to banish the dieter’s cravings for high-GI foods such as bread, rice, potatoes, pasta, and sugar. Alcohol, fruits, cereal, and such vegetables as carrots and corn are also restricted during Phase one. Instead, protein-rich foods are emphasized, such as lean meat, fish, eggs, cheese, nuts, and vegetables. Coffee and tea are also allowed. Three regular-sized meals are eaten each day, supplemented by mid-morning and mid-afternoon snacks as well as dessert. During this period, the body chemistry will change dramatically until cravings for high-GI foods are eliminated and insulin resistance is improved/lowered. In addition, rapid weight loss is typically experienced.
Phase two reintroduces several of the restricted foods and encourages eating from all the dietary food groups, the expected result being that the body will neither crave high-GI foods nor store food as excess fat to the same degree. Such high-fiber carbohydrates as whole-wheat pasta and bread and most fruits are now permitted. Moderation remains the key to success for this phase and low-GI foods are strongly encouraged. Phase two continues until the dieter reaches his or her ideal weight, ideally averaging a loss of one to two pounds per week.
Phase three, the ultimate goal, focuses solely on weight maintenance. Having reached the ideal weight, the dieter now makes the changed eating habits a lifestyle from this point forward. Basic dietary techniques are still maintained. Only the high-GI foods and "bad" fats from the previous two phases continue to be restricted. Altered body chemistry will promote long-term cardiovascular health and reduce the risk of diabetes. Should weight gain occur, Phase one of South Beach diet is reintroduced until the weight goal is achieved.
Preparations
There are no initial preparations required for the South Beach diet. However, as with most diets, it is wise to consult with a physician beforehand. Blood testing for insulin, glucose, and cholesterol levels is suggested. It is strongly recommended that dieters taking medications for medical conditions such as heart disease consult a physician before going on the South Beach diet. Similarly, diabetics on insulin or other medications are advised to have a doctor monitor their blood sugar regularly and determine if they are at risk of kidney impairment while on the diet. It is also recommended that a registered dietitian be consulted to determine the dietary needs of certain medical conditions, such as pregnancy.
Precautions
The South Beach diet is not recommended for people suffering from or at risk of kidney problems. The diet’s high protein content can place increased strain on the kidneys, possibly causing long-term damage as well as kidney stones and bone loss. Additionally, the possibility of ketosis-induced dehydration during Phase one can increase the risk of further kidney impairment. Dehydration occurs when the body experiences water loss with accompanying loss of important blood salts like potassium and sodium. Ketosis occurs when carbohydrates are not available and the body burns an excessive amount of fat, during which some ketones, or fat fragments, are excreted. The restrictive nature of Phase one may also induce mineral and vitamin deficiencies. Remaining in Phase one of the diet for longer than two weeks greatly increases the risk of losing bone and muscle mass. Dieters should remain in Phase one for no longer than three or four weeks.
Some nutrition professionals contend that the South Beach diet menus provided in the book lack important nutritional information and detailed portion sizes as well as specific substitutes for foods the dieter cannot or will not eat. They claim that these aspects, combined with the restrictive nature of the diet, can make sticking with the South Beach diet on a long-term basis difficult for some people. Also, they assert that the diet does not emphasize an exercise regimen and that exercise is vitally important to avoid the loss of muscle and bone mass, especially during Phase one of the diet.
Side Effects
Despite Dr. Agatston’s claims to the contrary, the South Beach diet is both a low carbohydrate and a low fat diet. For this reason, one main concern regarding the diet is the risk of ketosis, especially during Phase one. Ketosis can cause such symptoms as dehydration, dizziness, heart palpitations, fatigue, lightheadedness, and irritability. Hypoglycemia, low blood sugar, headaches, and excessive fluid loss are also commonly associated with this diet. Cramping and tired muscles can be incited by salt depletion. Kidney functions can be impaired, possibly leading to serious health issues. Kidney function can be further impaired by the diet’s high protein requirements. These side effects typically lessen or fade at the beginning of Phase two, when a more balanced diet is undertaken.
Research & General Acceptance
Unlike the majority of low-carbohydrate diets, the medical community generally accepts the South Beach diet. The South Beach diet contains all the major food groups, promotes ingestion of "good" fats for maintaining heart health, and is flexible enough to accommodate most dietary needs.
However, many clinicians and dietitians agree that the rapid initial weight loss results mostly from water loss. Much of this weight can return once the dieter rehydrates.
Another important criticism by medical and nutritional professionals is the lack of evidence to support Dr. Agatston’s claims connecting the consumption of low-GI foods and weight loss. They assert that as of the early 2000s, there is no scientific proof that eating low-GI foods will have any more weight loss effect than eating a normal, calorie-reduced diet that includes carbohydrates; that Dr. Agatston also fails to take into account the interaction of different foods when eaten together, which can dramatically alter glucose metabolism; and that this failure means that utilizing the Glycemic Index as a gauge for what foods to eat is not only confusing but also slightly misleading.
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