Power pill: nutrition science branched-chain amino acids may provide dramatic physical and mental boosts to your training - Personal Trainer - dietary supplements

Men's Fitness, April, 2002 by Michael Berg

Remember amino acids? Back in high school, while the burnouts were trying to score another bag of weed, all the jocks were hitting the weight bench and popping those all-important aminos. So how could you expect to get buff and score with the cheerleaders without downing your share every day?

Eventually, however, aminos went the way of your Z. Cavaricci's: out of style, and in a hurry. Unless you've really been hard-core into training and supplementation, chances are you haven't given a thought to those horse pills since.

The time has come to give them a second chance. Taking aminos isn't necessarily going to transform you into Conan-era Schwarzenegger, but research has revealed that certain aminos--specifically, branched-chain amino acids--may help protect your muscle during prolonged workouts, while giving your brain a "spot" at the same time.

JUST THE ESSENTIALS

Before understanding the benefits of BCAAs, you'll need to know what they are. In simple terms, BCAAs are made up of three amino acids: leucine, isoleucine and valine. Amino acids are the building blocks of protein, which in turn are the building blocks of muscle: 18 amino acids make up what is considered a "complete" protein, the type found in food sources such as beef, chicken, milk, eggs and protein powder.

Leucine, isoleucine and valine are considered "essential" aminos; that is, your body can't manufacture them on its own and thus needs to get them from your diet. After initial studies that showed promise for these particular aminos as muscle-building agents, BCAA supplements began to appear on the market.

So can taking BCAAs directly stimulate muscle growth? According to Eric Noreen, M.S., a doctoral candidate in the exercise nutrition research laboratory at the University of Western Ontario, Canada, some strong evidence suggests that BCAAs, specifically leucine, have the potential to be anabolic. "Several recent studies have shown that taking leucine after a workout significantly raises protein-synthesis rates [muscle growth]," he says. "It looks like leucine is an important component of the cascade of chemical signals that activate protein synthesis."

However, Noreen explains that the studies done thus far have been very narrowly focused on special circumstances and populations, which means the data can only be extrapolated to the recreational-athlete population. "Unfortunately, we really don't know what the real-world significance is," he says. "While speculating that the increased protein-synthesis rates will mean more muscle gains over time is reasonable, that conclusion hasn't been definitively established yet."

ENERGY BOOST

While no irrefutable evidence links BCAAs directly to muscle gain, some studies have shown they do augment energy levels, which would help someone weight-training or running, cycling or doing other forms of cardio. "A fair amount of BCAAs are used as fuel during prolonged, fairly intense exercise," Noreen says. "Endurance athletes need to get enough BCAAs in the diet to cover their normal needs plus the additional amount used during training."

BCAAs are unlike most other aminos in that your muscles use them for fuel, an eventuality that becomes more likely the longer a particular activity continues, such as during a long, intense workout or run. Thus, BCAAs may benefit your training indirectly by keeping muscle tissue from being burned by the body when primary energy stores run low. A 2001 American Journal of Physiology--Endocrinology and Metabolism study found that muscle protein was spared during post-exercise recovery when subjects took BCAAs; a 1996 study published in the journal Nutrition showed BCAAs can protect muscle-glycogen stores from being tapped. (Once glycogen is gone, muscles are the next stop for the body in its pursuit of fuel.)

A lot of research has also focused on the mental benefits of BCAA supplementation. A group of Swedish researchers published two studies, one in Nutrition and a second in Acta Physiologica Scandinavica, which showed the supplement had positive effects on the mood and mental function of endurance athletes.

Noreen says BCAAs may provide a boost to you mentally by simply helping to bar tryptophan from entering the brain, where it is transformed into serotonin, a chemical neurotransmitter that causes sleepiness. "The data is pretty clear that BCAAs could offset an increased production of serotonin, keeping you mentally sharp during prolonged endurance exercise," he explains. "However, what isn't clear yet is whether this equates to an increase in exercise performance."

A WORD OF CAUTION

To be fair, not all experts agree on the effectiveness of BCAAs. Dan Bernardot, Ph.D., R.D., L.D., associate dean of research at Georgia State University's College of Health and Human Sciences and co-director of the school's Laboratory for Elite Athletic Performance, contends that the majority of athletes get plenty of BCAAs from their diets and thus don't need to take BCAA supplements. But he does concede that if anyone might be short on protein, it would be an endurance athlete.