When the difference between first and last place is a matter of seconds, athletes are looking for ways to get an edge over their competition. Dietary supplements for athletes make big promises, but they're often not well-regulated and their health claims are sometimes dubious.
According to a study published in 2011 in the Journal of Sports Sciences, 5 percent to 20 percent of supplements marketed to athletes — even those marketed as "natural" — may contain banned substances that either are included intentionally or present via cross-contamination. These substances can show up in testing, which constitutes a serious ethics violation that may lead to medal forfeiture, disqualification or suspension.
Athletes are responsible for everything they put into their bodies and they cannot claim that they weren't aware of the risk of ingesting an illegal substance when taking performance-enhancing supplements.
Some ergogenic aids, however, do show promising results in studies. While the following ergogenic aids may help an athlete achieve performance goals, they are no substitute for a good training program and a tailored nutrition plan.
Beetroot juice is a potent source of dietary nitrate. It occurs naturally in vegetables such as arugula, rhubarb, butterhead lettuce, celery, spinach and red beetroot.
Dietary nitrate is reduced to nitrite and nitric oxide in the body, especially during times of low oxygen availability and acidosis, both of which can occur during exercise. The high nitrate content of vegetables recommended in the DASH diet may be partially responsible for the diet's ability to lower blood pressure.
Nitrate supplementation (usually about 200 milliliters to 500 milliliters per day) reduces the oxygen cost of exercise. This results in greater oxygen delivery to working muscles, which increases the capacity for high-intensity exercise. Several studies using well-trained cyclists and rowers show improved time trial results when beetroot juice was ingested in place of a placebo. A recent meta-analysis published in the Journal of the International Society of Sports Nutrition showed a small performance benefit in laboratory-measured exercise tests when 500 milliliters of beetroot juice was ingested daily for six days prior to exercise.
Beetroot juice appears to be safe, and the only noted negative side effect is "beeturia" (red-hued urine), but researchers don't know yet if high intake of nitrates over a long period of time will have negative health consequences. More research is needed to fully understand the mechanism, the most effective dose and the types of athletes who might benefit most from beetroot juice supplementation. That said, encouraging athletes to eat more nitrate-rich vegetables, including beetroot, is a sound practice.
Beta-alanine is an important precursor to carnosine, a lactic acid buffer. During high-intensity exercise that lasts for a few seconds to a few minutes (such as sprints), muscles primarily rely on the anaerobic energy system. Acidosis limits an athlete's ability to exercise at very high intensity. Athletes have tried buffering lactic acid with various nutrition strategies, including ingesting bicarbonate (baking soda), but many suffer stomach upset. Beta-alanine has the potential to increase carnosine, which in turn reduces acidosis. In doses ranging from 3 grams to 6.5 grams per day for two to 12 days, beta-alanine has been shown to increase the buffering capacity of lactic acid, but whether this leads to improvement in performance remains to be seen. Some studies have shown improvement in sprint performance while others have not demonstrated any benefit. High doses may cause paraestheisa (flushing and tingling), but slow-release forms of the supplement do not. More research is needed to determine precise performance benefits in athletes.
Branched-Chain Amino Acids
Branched-chain amino acids, including leucine, isoleucine and valine, are used by endurance athletes as an energy source late in exercise when muscle carbohydrate stores are low. Research suggests that BCAA also may delay mental fatigue by altering brain neurotransmitters that contribute to fatigue. The theory is sound, but there is not enough evidence to show that BCAA supplementation can delay fatigue.
Eating foods rich in BCAA is a smart move for athletes, but for reasons other than delaying fatigue. Leucine has been identified as an anabolic trigger to stimulate muscle protein synthesis. Leucine is a key amino acid in whey, a protein in milk. Milk may have a muscle-building advantage over other protein sources because milk protein contains both whey and casein.
Whey is a "fast" protein that is rapidly digested and absorbed, leading to a rapid rise in amino acids in the blood, while casein, a "slow" protein, results in a slower release of amino acids. The combined fast and slow release of amino acids leads to a more sustained availability of amino acids to muscles.
Creatine is found in meat and fish; a typical meat eater ingests about 1 gram of creatine daily. In muscle, creatine combines with phosphate to create a high-energy compound that resynthesizes ATP to perform muscular work, which in turn increases muscle mass.
Athletes who supplement with creatine typically take it in the preseason, particularly when weight training. Supplementing with 20 grams to 25 grams of creatine monohydrate for five to seven days, followed by 5 grams to 10 grams daily for up to two months increases muscle creatine content by about 20 percent, according to a study published in 2012 in the Journal of the International Society of Sports Nutrition. This can increase an athlete's ability to train, leading to improvements in strength and power.
Creatine monohydrate is the form used in research studies, but many other forms of creatine are marketed to athletes, claiming to provide advantages above and beyond creatine monohydrate. However, there is no evidence to support these claims.
Supplemental creatine has been around for about 20 years, and it is safe when used in the recommended doses. The supplement does not cause muscle cramping, nor has it been shown to cause kidney damage in healthy athletes, even among those following a high-protein diet.