The Science of Supplementation

Current evidence support the use of nutritional supplements to aid exercise performance and recovery.

While nutritional supplements have been advocated for decades to combat dietary deficiencies, in the past decade they have become an integral part of even mainstream America for assuring daily requirements and enhancing overall health. Advocacy of sports nutrition is a recent phenomenon and we are just beginning to understand its interaction with exercise. With the advent of the Internet, individuals are becoming bombarded by a host of nutritional sports supplements. The following text reviews current research findings regarding the efficacy of nutritional supplements in enhancing exercise and promoting health and fitness.

Essential Vitamins and Minerals

Vitamins and minerals have been established as essential because they cannot be created or synthesized by the human body and must be obtained from dietary sources. All of the major energy-producing reactions in humans have a requirement for these vitamins and minerals, particularly the B vitamin and minerals, while U.S. government surveys indicate that the average diet is consistently deficient in multiple nutrients. Examples include deficient intake of vitamin B1 in four out of 10 individuals, vitamin B6 (three out of 10), folic acid (eight out of 10) and chromium (nine out of 10). Even athletes with apparently adequate diets have been shown to have poor nutrient status when serum or cell levels are measured.

Nutrient deficiencies can have a clear impact on physical performance. As an example, restriction of vitamins B1 (thiamine), B2 (riboflavin) and B6 (pyridoxine) resulted in an overall significant decrease in aerobic power ([VO.sub.2]max; -11.6 percent), peak power (-9.3 percent), mean power (-6.9 percent) and faster onset of blood lactate accumulation (+12.0 percent). It should be noted that a limited number of studies have shown enhanced performance in athletes when supplemented with single or multiple combinations of vitamins and minerals, while most research has failed to demonstrate clear-cut improvements. However, the positive studies may be reflective of poor nutrient status in the selected subjects.

Since nearly all of the research on human performance has been short-term with protocols over several days to several weeks, the long-term benefits of supplementation have not been adequately recognized. For example, in a recent study on vitamin B6 supplementation, trained athletes exhibited lower plasma levels of free fatty acids, free amino acids, lactate and catecholamines after exhaustive exercise. These results are suggestive of more efficient metabolic processes, which may result in improved training and recovery, thereby translating into increased levels of fitness and performance over the long-term.

Antioxidants, Exercise and Vascular Health

The story of antioxidants has emerged over the past decade as one of the compelling paradigms of health and disease. Risk for heart disease, stroke, cancer, complications of diabetes and aging are all linked to the level of nutritional antioxidants present in our bodies. Since antioxidants protect tissues against dangerous free radicals, which are highly destructive molecules, the dietary intakes determine the relative level of protection. Free radicals are ubiquitous--they can't be avoided because they are generated from environmental pollutants, pesticides, drugs, smoking, UV radiation and normal metabolism. So if metabolism is increased through exercise, more free radicals are produced and more antioxidant protection is needed.

Although exercise is commonly promoted as a health-enhancing activity, it may have a dark side. Kenneth Cooper, M.D., M.P.H., well known as the father of aerobics, now believes that strenuous exercise--such as that associated with triathlons and marathons--can increase the risk for cancer and heart disease. Cooper also believes that antioxidants taken supplementally will combat the negative effects of exercise by protecting cells and tissues against destructive free radicals. Recently, it was discovered that LDL cholesterol particles are more susceptible to oxidative damage following intense exercise. As are well known, antioxidant nutrients such as vitamin E, vitamin C, carotenoids, polyphenol catechins from green tea, anthocyanins from grape skin and grape seed, lipoic acid from soy and coenzyme Q10 can reduce the susceptibility of LDL particles to oxidative damage.

Since the ATP required for effective heart function is derived primarily from mitochondrial respiration--in which coenzyme Q10 plays a pivotal role--it is evident that good coenzyme Q10 status is crucial for optimal cardiovascular performance. This is observed most dramatically in people who surlier from ischemic congestive heart failure or angina. Supplemental coenzyme Q10 typically increases cardiac output, diminishes peripheral resistance, lessens anginal symptoms and improves exercise performance in these individuals. Although fewer studies have examined the impact of coenzyme Q10 on healthy athletes, a double-blind study at the University of Bologna showed that supplemented Co Q10 (100 mg per day for seven weeks) improved the treadmill performance of well-trained male runners, increasing both their endurance time and speed.

Additionally, exercise-induced free radicals damage the muscle fibers themselves, as indicated by increases in serum levels of creatine phosphokinase. Chronic supplementation with antioxidants can overcome this muscle damage as evidenced by suppression of creatine phosphokinase release. The obvious benefit is reduced muscle soreness and faster recovery from exercise. Diet alone cannot adequately supply the protective levels of antioxidants that research studies indicate are necessary for even moderate physical activity levels. For example, daily intakes should be 300 mg of vitamin C, 200 IU of vitamin E, and 10,000 IU of beta-carotene--levels which cannot be easily achieved by dietary intake. In addition, many of the plant-derived phytonutrients described above are not easily obtained in meaningful amounts from the average diet.

Aids to Anaerobic and Aerobic Performance

Among supplemental nutrients, creatine is beyond doubt the best-documented aid to exercise performance. In tissues that have rapidly varying energy requirements, such as muscles and neurons, phosphocreatine serves as a crucial source for high-energy phosphate groups. Phosphocreatine is readily converted to ATP, which is used as the energy source in these organs. Typically, muscle cells have ATP stores sufficient for only one second of work while phosphocreatine levels provide the equivalent of 30 seconds of continual working energy. Creatine loading protocols using five grams four times daily for five days are usually effective for increasing muscle content of total creatine (free plus phosphocreatine) by as much as 50 percent. This increase in the muscle creatine pool has been shown to accelerate the resynthesis of phosphocreatine in the minutes following an intense bout of exertion, rapidly preparing the muscle for renewed exertion. In addition, phosphocreatine serves as a lactic acid buffer so increases in pool levels enhance the buffering capacity of muscle. The net effect of increased energy stores and added buffering capacity is to extend the anaerobic working capacity of muscle.

The most significant effect of short-term creatine loading is improved performance in brief maximal exertions repeated at short intervals--weightlifting sets or repeated brief sprints, for example. Although some studies suggest modest improvements in single maximal exertions, the more substantial and regular effect is to improve performance in the latter stages of repeated bursts of exertion. On the other hand, creatine loading usually does not improve performance in submaximal or aerobic exercise. Indeed, creatine supplementation has been attributed to gold medal performances by Britain's Linford Christie and Colin Jackson in the 1992 Olympic Games. Subsequently, the widespread popularity of creatine as a training aid was evident in the 1996 Olympic Games in Atlanta, Georgia. Reportedly, every medal winner in swimming and track and field sprint events was training with creatine.

When long-term creatine supplementation is used as an adjunct to effective resistance training, it often produces notable improvements in one-rep as well as multiple-rep maximal exercise performance. This evident increase in strength apparently reflects a greater increase in muscle mass that is distinct from the fluid retention observed with short-term creatine loading. Most authorities suspect that this creatine-induced increase in muscle bulk is primarily attributable to the fact that athletes are able to work harder during resistance training (which is precisely the type of exercise in which creatine aids performance). However, the possibility that creatine has some more direct impact on muscle anabolism in resistance training subjects cannot currently be excluded. In any case, supplemental creatine, especially when used long-term as an adjunct to training, has been found to be notably effective for increasing strength, sprint performance and lean mass gain. Current research now indicates that creatine supplementation at one to three grams daily, depending on body weight and intensity of workouts, is sufficient to maintain cellular levels in muscles.

As an individual progresses on the short-term needs of power events to that of more prolonged aerobic sports, there is a shift from the predominantly muscle-based energy stores (e.g., ATP, phospho-creatine, glycogen) to the larger systemic energy reservoirs. For the most part, these are comprised of liver glycogen and the more important adipocyts (fat cells). While the muscles still needs glucose during prolonged aerobic events, the predominant energy substrate is from fatty acids. Several studies have identified the rate-limiting mechanism for supplying these fatty acids to the muscle cell, which is primarily carnitine palmitoyl transuase (CPT), an integral part of the mitochondrial membrane responsible for the actual transport of free fatty acids into the mitochondria for energy production. Optimizing CPT concentration is important for allowing the muscle mitochondria to perform most efficiently.

The importance of free fatty acids in aerobic metabolism is best shown in cardiac muscle. Cardiac muscle functions primarily on a continuous aerobic energy cycle, thereby requiring constant availability of free fatty acids. There are numerous studies outlining carnitine supplementation for enhancing rest and exercise tolerance in heart patients. Improvement in athletic performance has been reported in a wide range of athletes (rowing, kayaking, swimming, long-distance running) using L-carnitine supplementation,

In another study, similar athletes given one gram of L-carnitine per day exhibited greater changes in free fatty acids, triglycerides, lactic acid after exercise, and plasma carnitine when compared to placebo controls. These supplemented athletes have more efficient delivery and utilization of free fatty acids for supplying energy during endurance and strength events. Moreover, maximal oxygen uptake and power output were found to improve in athletes consuming two grams of L-carnitine per day compared to placebo controls. In addition, during submaximal exercise, L-carnitine-supplemented subjects exhibited more efficient bioenergetics by reduced measures of plasma lactate, oxygen uptake and pulmonary ventilation, Besides the more efficient use of free fatty acids, L-carnitine may impact performance by reducing membrane damage. A recent study showed that L-carnitine supplementation reduces delayed muscle soreness and creatine kinase releases after eccentric exercise.

Although L-carnitine can be synthesized by the body, L-carnitine supplementation has been shown to increase muscle carnitine concentration by more than 31 percent. Furthermore, skeletal muscle biopsies from long-distance runners exhibited greater L-carnitine turnover and concentrations of L-carnitine when compared to sprinters. A recent study reported that muscle mass improvement and muscle metabolism were correlated with higher levels of plasma carnitine in 33 healthy subjects.

Building Muscle Mass and Reducing Body fat

Branched chain amino acids (BCAA)--which include leucine, isoleucine and valine--have a special role in muscle that promotes protein synthesis and/or impedes protein breakdown. In two studies, administration of BCAAs before or during extended endurance exercise has been shown to decrease muscle protein breakdown during the activity. In wrestlers undergoing caloric restriction to achieve weight loss, BCAA supplementation was reported to accelerate fat loss,

The trace mineral chromium has been shown to potentiate insulin, which is a well-known hormone for glucose control and transport. However, insulin is also an anabolic hormone, which enhances the transport of amino acids--particularly BCAAs and glutamine--into muscle. Two large placebo-controlled studies evaluated the impact of chromium supplementation on body composition and concluded that fat loss was expedited while lean muscle was preserved.

A combination of supplementation chromium and L-carnitine was effective in promoting weight loss and fat loss (10.9 lbs. in eight weeks) and resting metabolic rate was increased by an average of 40 percent. In two placebo-controlled studies, supplementation with L-carnitine resulted in significant weight loss and fat loss compared to the controls. Light exercise was a component in both studies and it appears that L-carnitine is most effective in promoting fat loss when muscle energy expenditure is increased.

Exercise Recovery

Glutamine is the most abundant free amino acid in human muscle and plasma. It is utilized by rapidly dividing cells, including leukocytes, to provide high energy and optimal conditions for nucleotide biosynthesis. As such, it is considered to be essential for proper immune function.

After very strenuous and prolonged exercise, plasma glutamine levels fall for several hours. Glutamine is avidly metabolized by lymphocytes and is indeed required for lymphocyte proliferation. This has prompted the suggestion that this temporary glutamine depletion may be at least partially responsible for the relative immune suppression observed in the hours following such exercise and the heightened risk for subsequent infection associated with it. When glutamine or a placebo were administered immediately after exercise and two hours later to rowers and marathon runners following competition, 81 percent of those receiving the glutamine remained free of infection in the subsequent week, as compared to only 49 percent of the placebo-treated athletes. Overtraining syndrome (which includes fatigue, muscle soreness and frequent infections) has been attributed to prolonged glutamine depletion. Glutamine supplementation after exhaustive exercise was shown to promote muscle glycogen resynthesis and whole body carbohydrate storage.

As mentioned earlier, prolonged exercise is associated with increased free radical damage, which contributes to fatigue, soreness and structural damage during and after such exercise. Administration of nutritional antioxidants in the weeks prior to an exercise bout has been found to decrease the associated free radical damage and suppress the subsequent increase in serum creatine phosphokinase, suggesting that antioxidants can lessen exercise-induced structural damage to muscle. Since antioxidants have various immune stimulant activities, supplementation should also have a positive impact on post-exercise immune suppression.

In summary, there is ample evidence showing that supplementation with a good multi-vitamin provides overall protection from dietary deficiency due to the diet itself, lifestyle and aging. Moreover, the incorporation of antioxidants like vitamin C, vitamin E and the newer class of carotenoids and plant phytochemicals offer protection from oxidative damage attributable to the environment, disease, aging and exercise. In addition, there are a number of specialized nutritional products that have been adequately scrutinized by research scientists and proven to be effective in enhancing performance, building lean muscle mass, reducing body fat and recovering from acute exercise.

Questions: The Science of Supplementation

1. Vitamins and minerals have been established as essential because:

A. they cannot be created or synthesized by the human body.

B. they must be obtained from dietary sources.

C. they are the key elements in fat metabolism.

D. A and B

2. Numerous studies indicate that exercise:

A. decreases the need for vitamins and minerals.

B. increases the need for vitamins and minerals.

C. has no effect on the body's need for vitamins and minerals.

3. U.S. government surveys indicate that the average diet:

A. contains more nutrients than previously thought.

B. contains adequate levels of essential nutrients.

C. is consistently deficient in multiple nutrients.

D. A and B

4. According to recent studies, where cell levels or serum is measured, athletes with apparently adequate diets have been shown to have:

A. excellent nutrient status.

B. satisfactory nutrient status.

C. poor nutrient status.

5. Nutritional antioxidant levels present in our bodies are linked to:

A. risk for heart attack and stroke.

B. cancer.

C. Complications of diabetes and aging.

D. All of the above

6. Free radicals are:

A. highly destructive molecules.

B. generated from environmental pollutants and radiation.

C. generated by normal metabolism.

D. increased through exercise.

E. All of the above.

7. Oxidized LDL is a mediator of:

A. good cardiovascular health.

B. increased muscle strength.

C. decreased muscle strength.

D. atherosclerosis process.

8. Recent studies suggest that increased intakes of antioxidant nutrients such as vitamin E, vitamin C, carotenoids, polyphenol catechins from green tea, anthocyanins from grape skin and grape seed, lipoic acid from soy and coenzyme Q10 can reduce the susceptibility of LDL particles to oxidative damage.

A. True

B. False

9. Many plant-derived phytonutrients such as carotenoids, polyphenol catechins, anthocyanins and lipoic acid can be easily obtained in adequate levels from the average diet.

A. True

B. False

10. Phosphocreatine levels provide the equivalent of:

A. 15 seconds of continual working energy.

B. 30 seconds of continual working energy.

C. 45 seconds of continual working energy.

D. 60 seconds of continual working energy.

11. Creatine loading protocols using five grams four times daily for five days are usually effective for increasing muscle content of total creatine (free plus phosphocreatine) by as much as:

A. 15 percent.

B. 25 percent.

C. 50 percent.

D. 75 percent.

12. Long-term creatine supplementation often produces notable improvements in:

A. one-rep exercise performance.

B. multiple rep maximal exercise performance.

C. aerobic capacity.

D. A and B

13. While the muscle needs glucose during prolonged predominant energy substrate is from:

A. fatty acids.

B. minerals.

C. vitamins.

D. All of the above.

14.Trace mineral chromium has been shown to potentiate:

A. insulin.

B. L-carnitine.

C. vitamin C.

D. All of the above.

15. Glutamine is the most abundant free amino acid in human muscle and plasma and is considered to be essential for proper immune function.

A. True

B. False

John A. Wise, Ph.D., is a nutritional biochemist and author of numerous studies on the health benefits of nutritional supplementation. He is the vice president for Science and Technology at Natural Alternatives International (NAI) in San Marcos, California.

Robert O. Voy, M.D., is former Chief Medical Officer and Director of Sports Medicine and Science of the United States Olympic Committee. He is currently a physician in sports medicine and family practice in Las Vegas, Nevada.

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