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Several Supplements Target Endurance Athletes

Can caffeine enhance endurance performance?

Caffeine has been considered a stimulant and is used by many individuals in normal daily life as well as by athletes. Caffeine and related substances are found naturally in foods and beverages, such as coffee, teas, and chocolate; and as part of recipes, such as in various soft drinks. Coffee contains caffeine whereas tea contains theophylline and chocolate contains theobromine. These factors are considered stimulants as they impact the CNS and increase alertness which alone can improve the enjoyment of exercise and help people perform at a higher level. Caffeine and related substances also enhance and prolong the effects of certain hormones such as glucagon and epinephrine in fat tissue. If fat release is increased and made more available to muscle then more fat might be used during aerobic exercise and improve performance and help lean the body.


Several studies have reported that the beneficial effects of caffeine on performance are negated in people who use caffeine daily (coffee, soft drinks, etc). However, by going caffeine free for several days prior to an event, caffeine may enhance performance. Recent studies have shown that caffeine ingestion can indeed enhance endurance performance. Based on the current research 3-6 mg/kg of caffeine prior to training or competition might enhance endurance performance. Meanwhile levels exceeding 9 mg/kg might decrease performance.


Caffeine seems to enhance mental alertness in smaller doses (200 mg), although many individuals complain of nervousness and anxiety when larger doses are used (> 400 mg). A cup of coffee contains 100 to 150 mg of caffeine while a cup of tea and cola contain 25 to 60 mg. The over-the-counter stimulant Vivarin contains 200 mg of caffeine per tablet. Caffeine is metabolized and removed from the body fairly slowly. It may take several hours for the caffeine in one cup of coffee to be completely removed in the urine.


Can glycerol support better hydration for athletes?

Glycerol has also been considered a candidate for supplementation during endurance events. This notion is based upon glycerol’s potential to be converted to glucose in the liver. The glucose could then circulate to muscle and support muscle operations during exercise. Theoretically, this could decrease the rate of breakdown of glycogen stores. However, it seems that the torpid rate of converting glycerol to glucose seriously decreases its candidacy.


Alternatively, glycerol supplementation in conjunction with water consumption may be of benefit to endurance athletes preparing to perform in warmer environments. It may be that glycerol can enhance water retention prior to an event and thus may allow more sweat to be lost prior to any reductions in performance due to dehydration. Scientists have also reported that glycerol supplementation prior to an event increases heat tolerance during competition in warmer environments—perhaps another potential aid for athletes competing in warmer environments without ample opportunity to drink fluids during training and competition. One example of this type of competition might be soccer. However, glycerol may lead to digestive tract discomfort so athletes will have to experiment here as well.


Should endurance athletes use antioxidants supplements?

Oxygen-based free radicals are normally produced in aerobic energy metabolism. During aerobic activities even more free radicals are created as energy expenditure increases several fold. In response, muscle produces and maintains greater levels of antioxidants. In addition, antioxidants from foods can incorporate into muscle and help keep free radicals at bay. This includes carotenoids, polyphenolics, vitamin C and E, lipoic acid and coenzyme Q. However, supplementing excessively large levels of these nutrients is not recommended. One reason is that research suggests that higher supplementation levels can blunt some of the naturally occurring adaptations in antioxidant systems in muscle.


Can endurance performance be improved with Coenzyme Q?

Coenzyme Q, also known as CoQ10 and ubiqui­none, can be found in the cells as a key component of the electron-transport chain. It also functions as an antioxidant as it has been used as a supplement by individuals who are taking statin drugs. Some of the earlier studies regarding the effects of supplemental CoQ10 on athletic performance were positive; however, more recent and better designed studies have failed to show a significant performance benefit of CoQ10 supplementation.


Can lipoic acid enhance performance?

Lipoic acid (α lipoic acid) is a naturally occurring substance in cells and is a key factor in the metabolism of energy nutrients. In addition, lipoic acid also functions as a muscle antioxidant. At this time researchers have not found that lipoic acid supplements provide a predictable performance benefit to athletes.


Can Medium-Chain Triglycerides (MCTs) increase performance?

MCTs contain fatty acids, which are both saturated and are only six to twelve carbons in length. The shortness of these fatty acids gives them unique properties, including the ability to (1) be absorbed from the digestive tract into the blood (portal vein) and not generally incorporated in chylomicrons; (2) provide a rapid energy source for the liver and muscle; and (3) possibly increase fat mobilization from fat cells. These properties make MCTs a possible candidate for supple­mentation during endurance events.


Theoretically, MCTs can slow glycogen breakdown and decrease some muscle protein breakdown during endurance exercise by providing a readily available energy source for liver and muscle. Researchers have indeed found that supplemented MCTs are used during endurance exercise however they seem to substitute for other fat and do not slow the rate of glycogen breakdown nor do they improve athletic performance.


Should choline be supplemented to enhance performance?

Choline is a component of acetylcholine, which is a neurotransmitter of great importance to skeletal muscle activity. First, nerve cells reaching skeletal muscle fibers release acetylcholine, which then stimulates them to contract. Also, choline is a component of phosphotidylcholine which is a structural component of muscle cell membranes. Choline, along with betaine (trimethylglycine [TMG]), dimethylglycine, sarcosine (N-methylglycine), methionine, and S-adenylsyl methionine, is involved in some of the processes that build several molecules which may be important for muscle performance, such as creatine and nucleic acids. Choline supplementation for the purposes of enhancing athletic performance (with and without other substances) requires further study.


How do Sport Drinks help performance?

Sport drinks were pioneered in the 1960s when a scientist at the University of Florida (home of the Gators) developed a product designed to provide fluid, energy, and electrolytes to athletes. The product became known as Gatorade, and a multimillion-dollar industry was born.


Sweat is a combination of mostly water and electrolytes. It is needed to help remove the excessive heat generated from the body during exercise. One liter of sweat allows for the removal of 580 calories of heat from the body. So, if an activity such as running for two hours generates about 900 Cal of heat, then theoretically about 1.5 L of sweat may have been lost. The primary electrolytes lost from the body in sweat are sodium and chloride. However, their concentration in sweat is lower than in the plasma of the blood. Thus, sweat is dilute compared to blood. Even when sweating profusely the sodium and chloride content of the sweat may be only about one-half of the concentration of human blood plasma.


What is the composition of sport drinks?

Sport drinks provide fluid, energy and electrolytes and possibly other nutrients such as protein, amino acids, calcium, magnesium, B-complex vitamins and antioxidants. The energy in sport drinks is provided largely in the form of carbohydrates such as glucose, sucrose, fructose, corn syrup, maltodextrins, and glucose polymers. Maltodextrins and glucose polymers are mostly cornstarch that is partially broken down. Glucose and fructose are monosaccharides, whereas corn syrup is derived from cornstarch, which has been partially broken down to short, branching chains of glucose. Maltodextrin is just a few glucose molecules linked together with a branching point. Glucose polymers may just be short chains of glucose. Carbohydrates usually make up about 6 to 8 percent of the sport drink. Recently protein and amino acids have been formulated into sports drinks with research suggesting better hydration, performance and recovery.


How does the carbohydrate in sport drink help sustain performance?

One of the principal factors involved in the onset of exhaustion or fatigue is a depletion of muscle glycogen stores. The carbohydrate in sport drinks becomes an available source of glucose to working muscle. It was once thought that the carbohydrate in a sport drink might slow the rate of glycogen breakdown and thus prolong endurance exercise. However, research has shown that the carbohydrate in a sport drink actually becomes an increasingly more important carbohydrate source for working muscle as glycogen stores wane. This contribution seems to be significant enough to push back fatigue by minutes or more. This could be the difference in finishing strong during a marathon or fatiguing in the last couple miles. 


Who would benefit from a sport drink?

For a well-nourished and hydrated weight-training athlete, there is probably not a need for a sport drink unless he or she is training for several hours and sweating profusely. The need for sport drinks for endurance athletes largely depends on the duration of exercise and the environmental conditions. Generally, for single shorter events such as 5K runs and half-hour aerobic sessions there isn’t a need. However, as an event or training session becomes longer, the need increases. For bouts lasting an hour or thereabouts, water replacement is certainly necessary and performance can be enhanced by a sport drink.


Even athletes competing in intermittent effort yet longer duration sports such as soccer, ice hockey, and football can benefit from a sport drink. These sports are powered by muscle glycogen and a sport drink can improve performance in repeated sprinting efforts. Plus for sports such as ice hockey and football uniforms and gear can increase sweating and thus the need for fluid to maintain optimal hydration.


Can fortified water/fitness water help performance?

Over the past few years numerous enriched waters or fitness waters. These beverages tend to be low calorie (e.g. 10 calories per 8-10 ounces) and include electrolytes with or without calcium, magnesium and B-vitamins. While these beverages are not advantageous for more strenuous and/or prolonged athletic efforts they are good options for maintaining optimal hydration especially in the heat (e.g. walking or a half hour or so on the elliptical or weight lifting.





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