Antioxidant Pills May Reduce Gains From Exercise

December 4, 2014 Updated: December 4, 2014

Several recent studies show that taking antioxidant pills limits the improvement gains in endurance and strength in exercisers. To increase strength and endurance through exercise, you have to exercise vigorously enough to damage muscles. When muscles heal, they are stronger. Recent data show that healing of muscles (and thus gains in strength and endurance) are delayed by taking antioxidant pills. Muscle healing is also delayed by taking non-steroidal anti-inflammatory drugs such as ibuprofen.

Antioxidant Pills Reduce Gains in Strength

Researchers assigned 32 experienced male and female weight lifters to two groups: one group that took daily 1,000 mg of Vitamin C and 235 milligrams of Vitamin E, and another group that was given placebos. All participants took the same rigorous progressive weight-training program four times a week for 10 weeks. An example of their workout is four times a set of eight Repetitions Maximum (8RM) of leg presses and knee-extensions. Both groups grew larger muscles, but the lifters who took the placebos gained more strength. Furthermore, the subjects who took the antioxidant pills had lower levels of the enzymes that synthesize proteins. This is important because muscle growth requires muscle damage and the growth occurs only with healing. That is why you have to lift weights “to the burn” to grow larger muscles. Antioxidant vitamin pills reduced the levels of enzymes that heal muscles to make them stronger.

Mechanism of Antioxidant Pills Limiting Gains in Strength

When muscles are damaged, they release tremendous amounts of free radicals into the surrounding tissue. The free radicals do not cause the damage; they are released by damaged tissue to start and accelerate the healing and growth process called inflammation. Blocking free radicals blocks inflammation, which blocks the start of the healing process, and retards muscle growth gains from exercise. We know from other studies that non-steroidals such as ibuprofen, that are taken to block pain, also delay healing from exercise in athletes.

Antioxidant Pills Limit Gains in Endurance

Taking the antioxidants (1000 mg vitamin C and 235 mg vitamin E) daily prevented improvements in fitness and endurance that would normally occur from an 11-week intense running program. Fifty-four young, healthy men and women received either the vitamin C and E pills or placebo. They ran hard intense intervals three or four times a week for 11 weeks. After the program, they were tested for proteins that increase the size and number of mitochondria in cells, a measure of endurance. Those who took placebos had a rise in these proteins, while those who took the antioxidants did not.

Every muscle cell has hundreds or even thousands of mitochondria. Mitochondria convert food to energy by moving electrons from one molecule to another, causing extra electrons to accumulate in tissues. If the extra electrons attach to hydrogen, they are converted to water which is harmless. However, if the electrons attach to oxygen, they become reactive oxygen species (ROS) that can damage cells and during exercise, worsen muscle burning, soreness and fatigue. The human body produces antioxidants that help protect a person from cell damage from these oxidants (ROS).

Contracting muscles markedly increase their conversion of food to energy, so they produce lots of extra electrons to make more ROS. However, exercising muscles produce far more antioxidants to rid themselves of the extra ROS, and muscles of regular exercisers produce more antioxidants than those of non exercisers and therefore remove ROS more rapidly from their cells. Giving large doses of vitamin C to people before they exercise appears to block antioxidant production by the exercising muscles, increases levels of ROS, and tires people earlier during exercise.

Antioxidants Limit Production of Mitochondria

The limiting factor to how fast an endurance athlete can move is the time it takes to move oxygen into muscles. You have two major sources of energy for your muscles during exercise:
* The Krebs Cycle, inside mitochondria, that uses oxygen, and
* Glycolysis, inside cells but outside mitochondria, that does not require oxygen.
The Krebs Cycle provides far more energy than glycolysis. Training for sports increases the size and number of mitochondria inside cells to make you stronger, faster and have greater endurance. Taking antioxidant supplements for 11 weeks did not limit the measured maximal ability to take in and use oxygen, but it did limit production of new mitochondria. This would be expected to hinder performance over an extended period of time.

Antioxidant Pills May Delay Muscle Healing

A review of the scientific literature concluded that taking large doses of vitamins C and E neither prevents nor treats muscle damage caused by intense exercise. However, taking one gram of vitamin C per day for 8 weeks tired male athletes earlier during long- term exercise. Similar doses per body weight reduced the distance Wistar rats could run. The authors showed that taking vitamin C pills prevents the growth of new mitochondria that are necessary for a training exercise program to increase endurance by blocking the expected exercise-induced increase in key factors that make new mitochondria: peroxisome proliferator–activated receptor co-activator 1, nuclear respiratory factor 1, and mitochondrial transcription factor A, and also prevented exercise-induced increase of cytochrome C (a marker of mitochondrial content) and of the antioxidant enzymes superoxide dismutase and glutathione peroxidase.

What Does this Mean for You?

These studies and many others suggest that antioxidant pills such as vitamins A, C and E interfere with exercise gains in strength and endurance. Other studies show that these antioxidant pills also do not prevent heart attacks, diabetes, or cancers unless a person suffers a deficiency of these vitamins. 

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