The Acid Test

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If a team of scientists assembled to create the perfect sports nutrition supplement for athletes, they’d focus on promoting endurance, because fatigue is the enemy no matter whether you’re a weightlifter or a long-distance runner. And any competitor wants to spend as little time on the sidelines as possible, so quicker recovery from bouts of activity is a welcome benefit.

Luckily, nature has already delivered a substance that meets those criteria. Amino acids — the building blocks of protein — possess an incredible range of benefits for those seeking improved energy and performance. Here’s a closer look at the many advantages of aminos and how to put this “perfect supplement” to work for you.

Branching Out

There are 20 amino acids found in protein, half of which are considered essential and must be obtained through the diet. The other half are nonessential and are produced naturally in the body. (The amino acids glutamine and arginine are categorized as nonessential and essential, respectively, but are sometimes called conditionally essential because although they can be manufactured in the body, they must be obtained through the diet in times of physical stress like illness or intense exercise.)

All 20 amino acids are key players in metabolism and cellular processes — when you’re deficient in them, your body will break down precious muscle tissue to obtain them.

When it comes specifically to exercise recovery and endurance, three essential amino acids step to the forefront. Leucine, isoleucine and valine — known collectively as branched-chain amino acids because of a chemical structure similarity they share — have protective effects in the body during exertion. Taking BCAAs before and after exercise promotes muscle recovery by decreasing exercise-induced muscle damage and increasing muscle-protein synthesis, as noted in the September 2008 issue of The Journal of Sports Medicine and Physical Fitness.

In another study, published in February 2009 in the Journal of Nutritional Science and Vitaminology (Tokyo), researchers had eight male athletes drink a mix that included BCAAs and carbs on a daily basis for six days, and specifically 15 minutes before exercising. Based on performance markers, they found that taking BCAAs before a bout of training increased endurance.

A combination of several amino acids — the BCAAs, along with arginine and glutamine — may improve exercise efficiency too. Researchers reporting in the February 2006 Journal of Nutrition noted that the combo appears to do this by positively affecting muscle integrity and the formation of blood and blood cells, as well as by decreasing muscle damage and fatigue after exercise. What’s more, the researchers noted that this performance-enhancing effect is dose-dependent: The greatest benefits were seen in athletes who took 6.6 grams per day of the amino-acid mixture compared to those who took 4.4 or 2.2 grams per day.

Energy to Spare

In discussing amino acids for exercise, it is also important to consider protein and carb intake because of how they contribute to the body’s energy stores. Together, these three nutrient groups can increase muscle glycogen, which decreases fatigue during exercise.

“Muscle glycogen is the predominant source of stored carbohydrate in the body, and it has been well-established that an adequate supply of muscle glycogen is essential to support exercise at competitive intensities,” says James Betts, Ph.D., a lecturer in the Human Physiology Research Group, School for Health, University of Bath, United Kingdom. Put simply, muscle glycogen is essential to exercise, and fatigue sets in once muscle glycogen is used up.

This idea — and the fact that research has shown that muscle glycogen can be restored more quickly when athletes take a carbohydrate supplement with added protein — was the basis for Betts and his colleagues’ research. In one study published in the November 2007 Journal of Sports Sciences, researchers showed that athletes who took a carbohydrate supplement with added whey protein isolate were able to run for 10 percent longer at 70 percent VO2 max (a measure of cardiovascular endurance) than participants taking the carbohydrate supplement alone.

Similarly, professional cyclists who ingested a carbohydrate-protein supplement with added electrolytes and L-glutamine exercised 55 percent longer before exhaustion than cyclists who drank a carbohydrate-electrolyte sports beverage. Writing in the February 2003 issue of The Journal of Strength and Conditioning Research, the scientists concluded that this may have been because of greater muscle glycogen storage.

To test this, they conducted a second phase of their study. The cyclists took a two-hour ride at 65 percent to 75 percent of their VO2 max, then drank one of the two beverages immediately and two hours afterward. Those taking the carbohydrate-protein beverage had a 17 percent greater plasma glucose response, a 92 percent greater insulin response and 128 percent greater muscle glycogen storage than the athletes relying on the basic sports drink.

Increased plasma glucose “increases glucose availability to the recovering muscles,” explains John Ivy, Ph.D., co-author of the study and department chair of kinesiology and health education, Teresa Lozano Long Endowed Chair, University of Texas at Austin. He adds, “The higher insulin response is important because insulin stimulates muscle glucose uptake and the formation of muscle glycogen.”

Ivy also commented on the L-glutamine in the supplement, saying it may have contributed to the enhanced performance. “L-glutamine could help, as it can be converted into glycogen in the liver,” he explains. “The glycogen in the liver is used to support blood glucose during exercise. The more liver glycogen one has, the longer he or she can exercise without becoming hypoglycemic. L-glutamine may also prevent the buildup of toxic products normally produced during exercise.”

Natural Selection

Used in a nutrition regimen that includes ample carbohydrates and protein at critical junctures, amino acids make for a potent weapon in the battle against fatigue.

The benefits of amino-acid supplementation include enhanced muscle glycogen stores, improved muscle recovery and decreased muscle damage — all of which coalesce to help athletes perform longer and stronger. Nature, with a boost from science, comes through again.

Team Players

The following nutrients work hand in hand with amino acids, helping you get the most out of amino supplements.

  • Electrolytes: These charged ions include sodium, potassium, chloride and bicarbonate. Sodium and potassium are positively charged cations that affect muscle function by generating electrical signals to the muscles and regulating muscle function, respectively.
  • Complex Carbohydrates: Also known as starches, complex carbohydrates contain vitamins, minerals and iber, and they are composed of long, complex chains of sugar molecules. Complex carbs are converted to glucose in the body for energy; any glucose that goes unused is stored as glycogen in the muscles and liver for later use.
  • Whey Protein: Derived from cow's milk, whey protein is a rich source of essential amino acids that is sold in three forms: whey protein concentrate, whey protein isolate and hydrolyzed whey protein. The purest form, according to the Whey Protein Institute, is whey protein isolate, which contains almost no fat, cholesterol or lactose.