By JERRY BRAINUM Iron Man Magazine
New Studies: Leucine, Carbs, Whey and More
Unless otherwise indicated, the following studies were presented at the 2011 meeting of the American College of Sports Medicine.
Does leucine help older men make muscle gains? While all amino acids are important to health, if I were to single out the aminos that provide the greatest benefit to bodybuilders, without a doubt that would be the branched-chain amino acids. The BCAAs consist of three aminos, all of which are categorized as essential amino acids, meaning that they must be provided in the diet and cannot be produced in the body: leucine, isoleucine and valine. Of the three, leucine has the most bodybuilding potential.
Leucine works by stimulating a pivotal substance in protein synthesis called the mammalian target of rapamycin, or simply mTOR. Stimulating mTOR starts a cascade of biochemical reactions that culminate rapidly in muscle protein synthesis. Some studies show that as we age, a type of anabolic resistance ensues. The body becomes resistant to the anabolic effect of amino acids.
One possible way around that problem is to increase leucine, but you must also ensure the presence of other essential amino acids, since complete muscle protein synthesis cannot occur unless all nine essential amino acids are present. Leucine works to kick-start the process.
The effects of leucine on body composition and strength in older men was examined in a study presented at the 2011 American College of Sports Medicine meeting. Twenty-three untrained men, average age 61, were randomly divided into two groups:
1) Those who got leucine, three grams a day, plus five grams of carbohydrate
2) Those who got only five grams of maltodextin, the carbohydrate
Why the authors chose such a small amount of carbohydrate wasn’t discussed in the study. The important aspect was how the supplemental leucine would affect the older men’s training progress. They trained three times a week, using weights equivalent to 75 percent of their one-rep maximums doing three sets of 10 reps per exercise. The men were tested on strength gains throughout the course of the 12-week study. Those who got the supplemental leucine showed significantly more strength gains in their one-rep-maximum leg press than those who got only carbs. So leucine does appear to promote strength gains in older men.
Arginine and muscle strength. These researchers wanted to determine the effects of supplemental arginine on upper-body strength in young bodybuilders. Twenty men, average age 24, were randomly assigned to either an arginine group (12 grams a day) or a cornstarch-placebo group. It was a double-blind protocol, meaning no one knew who was getting what
After eight weeks the arginine group showed significantly greater strength gains in terms of the number bench press reps they performed using a weight equal to 87.5 percent of one-rep max. The authors didn’t discuss why arginine was able to do that.
Whey vs. casein in older men. Researchers investigated the effects of whey vs. casein, the two primary milk proteins, in 36 untrained older men, average age 62, who underwent a weight-training program. They were divided into groups, with one group getting 20 grams of whey protein and five grams of carb, and the other getting 20 grams of casein with five grams of carb. A third group got a placebo containing 25 grams of carb. The men trained three days per week for 12 weeks, doing three sets of 10 reps per exercise with a weight equal to 75 percent of one-rep maximum.
At the end of 12 weeks the men in both protein groups had higher insulinlike growth factor 1, an anabolic hormone, than the carb group. They also had higher testosterone. Since both IGF-1 and testosterone are known to boost the activity of muscle satellite cells, the stem cells required for muscle growth, these results suggest that both types of milk proteins provide significant anabolic effects for older men.
In another study presented at the conference casein and whey effectively boosted muscle strength in older men and so could be a useful resource in combating age-related muscle wasting.
Does a low-carb diet limit strength gains? Can following one of the popular low-carbohydrate diets cause bodybuilders to lose strength? A study that included 16 trained men and 15 trained women examined that question. The subjects ate their usual diet for a week, followed by a week on a low-carb diet. The authors ensured compliance with the low-carb diet by measuring ketones, incomplete by-products of fat metabolism that increase during low-carb diets.
The subjects showed significant decreases in body and fat mass with just a week of low-carb dieting. They lost considerable amounts of body water, a frequent characteristic of low-carb diets, as glycogen is rapidly depleted. Each gram of stored glycogen holds 2.7 grams of water, so when glycogen is broken down, water is released. The subjects ate fewer total calories with the low-carb diet but also ate more fat and protein than they did on their usual diets.
Despite the loss of body mass, all of the subjects maintained their strength during their low-carb diet. The reason that they ate fewer calories was thought to be due to the higher production of ketones, which have an appetite-suppressing ability and are one of the key reasons that low-carb diets are more effective for weight loss. The body mass loss was largely water, again likely because of the loss of sodium and breakdown of glycogen.
This study underscores the empirical experience of countless competitive bodybuilders that low-carb diets are the most effective plans for inducing excess bodyfat loss while maintaining muscle, particularly if the diet is also high protein.
Another study presented at the conference examined the effects of low-carb dieting on peptides—small proteins known to control appetite. The specific peptides examined were leptin and peptide YY. The primary finding was that eight weeks of aerobic exercise combined with a low-carb diet led to bodyfat losses but no drop in leptin and PYY, which prevented surges in appetite that would have made the diet much more arduous. That effect, in addition to the elevated ketones, is what makes low-carb dieting much more effective for fat loss than the usual high-carb, low-calorie plans, which often result in uncontrolled appetite increases that spell doom to any diet.