Antioxidant vitamins
are enormously popular with people who exercise. The supplements are
thought to alleviate muscle damage and amplify the effects of exercise.
But recent studies have raised questions about whether antioxidants
might be counterproductive for runners and other endurance athletes. And
now a cautionary new experiment adds to those doubts by finding that
antioxidants may also reduce the benefits of weight training.
It is easy to see why
people might think that antioxidants like vitamins C and E could be
helpful to anyone who works out regularly. Both aerobic exercise and
strength training lead to the production of free radicals, molecules
that in concentrated amounts can cause tissue damage. Antioxidants sop
up and neutralize free radicals. So, the thinking goes, taking
antioxidant should lessen some of the damage and soreness after exercise
and allow people to train harder.
But recent experiments with endurance athletes
have found that consuming large doses of vitamins C and E actually
results in a slightly smaller training response. The athletes taking
these vitamins had lower levels of certain enzymes that spur an increase
in mitochondria in muscle cells. Mitochondria help to create cellular
energy, and having more of them allows people to exercise longer and
harder. By blunting the creation of mitochondria, the vitamins had
lessened the expected increase in fitness.
But those studies
looked only at endurance sports such as running and cycling, not weight
training, which involves different biochemical processes within muscles.
So for the new study, which was published online this month in The Journal of Physiology,
scientists at the Norwegian School of Sports Sciences in Oslo and other
institutions, some of whom previously had studied aerobic exercise and
antioxidants, set out to repeat those experiments in a weight room.
They began by
recruiting 32 men and women who had at least some experience with weight
training. They measured the volunteers’ muscular size and strength.
Then they randomly
divided them into two groups. Half were asked to start taking two
antioxidant vitamin pills each day, one before and one after exercising.
The total daily dosage amounted to 1,000 milligrams of Vitamin C and
235 milligrams of Vitamin E, which “is high but not higher than athletes
commonly use,” said Goran Paulsen, a professor at the Norwegian School
of Sports Sciences who led the study.
The other group did not take any supplements.
All of the volunteers
then began the same resistance-training regimen, consisting of four
fairly rigorous training sessions each week. As the exercises grew easy,
weights were increased, with the aim of pumping up the size and
strength of the volunteers’ muscles.
The program lasted 10
weeks. But midway through that time, the researchers took small samples
of muscle tissue from each volunteer in order to determine what,
precisely, was going on deep within each volunteer’s cells.
Then the men and women
finished the remainder of the program, at the end of which the
researchers again measured their strength and muscle size.
In general, people’s
muscles had increased in size to the same extent, proportionally. The
group that had taken the vitamins now had larger muscles. So did the
group that had not.
But there were subtle
but significant differences in their strength gains. Over all, the
volunteers who had taken the antioxidants had not added as much strength
as the control group. Their muscles were punier, although they had
grown in size.
The differences
continued beneath the skin, where, as the muscle biopsies showed, the
volunteers taking the vitamins had reduced levels of substances known to
initiate protein synthesis. Protein synthesis is necessary to repair
and strengthen muscles after weight training. So the volunteers taking
the vitamins were getting less overall response from their muscles, even
though they were following the same exercise program.
Exactly how
antioxidant pills change muscles’ reactions to weight training is still
unknown. But Dr. Goran and his colleagues speculate that, by reducing
the number of free radicals after exercise, the vitamins short-circuit
vital physiological processes. In this scenario, free radicals are not
harmful molecules but essential messengers that inform cells to start
pumping out proteins and other substances needed to improve strength and
fitness. Without enough free radicals, you get less overall response to
exercise.
Dr. Goran believes
that the same process occurs after endurance exercise, although the
specific biochemical signals and pathways are different.
The upshot is that
whether you lift weights or jog, Dr. Goran would advise “against the use
of high-dosages of concentrated antioxidant supplements.”
Of course, his advice
does not apply to anyone with an actual deficiency of one of the
antioxidants, he said, although that condition is rare. He also doesn’t
suggest that we avoid orange juice or other natural sources of vitamins C
and E while training. “But large volumes,” he said, “would be
unnecessary.”
