Exercise with supplements may benefit older muscles

NEW YORK (Reuters Health) - Two popular dietary supplements may enhance the effects of strength training on older adults' muscle and body fat, a small study suggests.

Canadian researchers found that a combination of exercise and the dietary supplements creatine and conjugated linoleic acid appeared to boost muscle strength and trim body fat more than exercise alone in a small group of healthy adults older than 65.

The findings are published in the online journal PLoS One, a publication of the Public Library of Science.

Creatine is an amino acid produced by the body to infuse muscle cells with energy for short bursts of activity; some research suggests that creatine supplements can help improve muscle mass and strength.

Conjugated linoleic acid is a fatty acid found in beef, lamb and dairy products. Animal research has suggested that supplemental conjugated linoleic acid can help melt away body fat, though studies in humans have come to mixed conclusions.

Researchers led by Dr. Mark Tarnopolsky of McMaster University in Hamilton, Ontario recruited 19 men and 20 women older than 65 to start a 6-month exercise regimen.

All of the study participants attended strength-training classes twice a week. Half took creatine and conjugated linoleic acid supplements each day, while the rest were given placebo "supplements."

By the end of the study, Tarnopolsky's team found that the supplement group showed some benefits beyond those of the exercise-only group. On average, they were able to work their muscles for a longer period and they showed greater strength in their thigh muscles. On top of that, they had a greater decline in body fat.

The potential side effects of creatine include dehydration, muscle cramps and diarrhea; conjugated linoleic acid may also cause gastrointestinal side effects. There were, however, no significant side effects from the supplements reported in this study, according to Tarnopolsky and his colleagues. Only one person complained of stomach cramps.

Still, it's too soon for older adults to head to the health-food store in search of creatine and conjugated linoleic acid.

The long-term effects of the supplements remain unclear, the researchers note, and larger trials are needed to confirm the benefits seen in this study.

SOURCE: PLoS One, online October 3, 2007.