To expand their muscles, some bodybuilders pop amino-acid supplements as though they were harmless sweets. Other builders have employed a number of illicit strategies, including injecting themselves with anabolic steroids and human growth hormone.

Since human growth hormone, a chemical secreted by the pituitary gland, chops away at fat and stimulates muscle growth, it produces the effect which bodybuilders want. Many builders don't want to inject growth hormone (or anabolic steroids), however, and have searched for some other way to boost their natural levels of the compound. Often, they have turned to a dietary supplement called arginine.

At first glance, that choice doesn't seem to be a bad one, since arginine is an amino acid which can have a powerful impact on growth hormone secretion. When arginine is given intravenously to patients recovering from surgery or trauma, it bolsters growth hormone production and dramatically lessens the loss of lean tissue. Some scientific studies have suggested that orally ingested arginine supplements can enhance gains in strength and muscle mass in athletes engaged in weight training.

To determine whether arginine can really help bodybuilders bulk up, researchers at the Virginia Polytechnic Institute in the US recently studied 12 male weight trainers. The men had been engaged in resistance weight training for at least two years, worked out from three to six times per week, and had not used anabolic steroids during their training. Individuals who were using amino acid supplements stopped taking them two weeks before the study began.

Subjects followed a standard, weight-maintenance diet for the first week of the study, with 55 per cent of calories coming from carbohydrate and 30 per cent from fat. During a subsequent 10-day period, the weight trainers consumed a hypocaloric diet which provided only 1700-1800 calories per day. This reduced intake is typical for bodybuilders who are trying to 'get ripped' (lose fat and become more sinewy).

During the 10 low-calorie days, half of the strength trainers consumed .2 grams of arginine per kilogram of body weight per day (about 1.6 total daily grams of the chemical). Half of the daily arginine was taken in the morning on an empty stomach; the other portion was consumed just before going to bed. A second group of bodybuilders abstained from arginine and swallowed only a placebo. Resistance training continued throughout the 17-day study (seven days of regular eating and 10 hypocaloric days) and was identical in the two groups.

At the end of the 10-day low-calorie period, both arginine and placebo ingesters had lost about seven pounds of weight. Body-fat levels dropped by a remarkable 16-20 per cent (from about 12 to around 10 per cent), while fat-free (muscle) weight held steady (compared to the placebo group, arginine supplementers did not augment muscle mass). In fact, muscle function declined during the 10-day period for both groups; biceps- and quadriceps-muscle strength dipped significantly.

Growth hormone levels WERE higher in the arginine group, but they didn't lead to larger muscles. It's possible that the growth hormone advances associated with arginine were too limited in amount - or too short in duration - to make any difference to muscle mass. However, it's also possible that the 10-day restriction in calories was too severe to permit any muscle-mass enhancement in the arginine people.

Since the arginine ingesters were not different from the placebo athletes, the Virginia scientists concluded that their findings do not support the use of oral arginine supplements by males involved in resistance weight training. Athletes engaged in strength training should also be aware that sharp reductions in food intake can trim away body fat, but they can also hurt performance. The athletes' biceps and quads were about 10-per cent weaker following their hypocaloric diets.

('The Effect of Oral Arginine During Energy Restriction in Male Weight Trainers,' Journal of Strength and Conditioning Research, vol. 8(3), pp. 170-177, 1994)