Contact: Donna Krupa703.527.73457Cell: 703.967.2751[email protected]
CAN VITAMIN E SUPPLEMENTATION FORESTALL MUSCLE-DAMAGING EFFECTS OF A SINGLE BOUT OF RESISTANCE TRAINING?
Vitamin E may enhance insulin production by the pancreas; results being presented at a meeting on exercise and physiology by international scientists during Olympics
PORTLAND, ME -- Exercise has been shown to lead to the formation of membrane-damaging oxygen free radicals. The damage created by these free radicals has been associated with the loss in muscle function and insulin sensitivity that intense exercise induces, says Bruce Craig, Ph.D. Dr. Craig is a member of the Human Performance Laboratory at Ball State University in Muncie, IN and will present his findings during the American Physiological Society's interdisciplinary meeting, "The Integrative Biology of Exercise," being held September 20-23, 2000 in Portland, ME.
Background: Free radicals are unstable and tend to react with the fats within the cell membrane. Vitamin E is a fat-soluble vitamin that acts as an antioxidant; it is important in the formation of red blood cells and has been shown to protect the cell membrane against free radical damage. Its effectiveness has been demonstrated in aerobic exercises like running, but has not been adequately tested with anaerobic training, such as weight lifting.
Methodology: To determine if three weeks of vitamin E supplementation could hinder the muscle-damaging effects of a single bout of resistance training, Dr. Craig and his colleagues studied the effect of short-term (21 days) vitamin E supplementation upon muscle function and hormonal responses following a single bout of resistance (weightlifting) exercise.
Eleven college-age male subjects were given 1200 IU of vitamin E or placebo capsules daily for 3 weeks. On day 15 the subjects were given a 75 gm glucose (sugar) drink and blood levels of glucose, insulin, and C-peptide (pancreatic-released hormone) were measured. Muscle power tests (the time it takes to lift a weight) were performed on day 16 and at 24 hours and 48 hours after the final weightlifting session. On day 21, the subjects exercised by lifting weights, and 45 minutes later were given a second glucose drink, followed by a re-testing of their muscle power.
Bruce Craig, Ph.D.Release - Page Two
Results: Results of the study showed that vitamin E significantly reduced the blood levels of creatine kinase, which is an enzyme marker of membrane damage. Vitamin E intake also reduced the formation of malondialdehyde, a blood marker of free radical formation. The protective effects of vitamin E did not, however, influence muscle power or strength. The glucose test performed on the subjects also demonstrated that three weeks of vitamin E intake can significantly elevate hormonal responses without influencing the body's ability to remove glucose from the circulatory system.
Conclusions: The conclusions drawn from this research suggest that vitamin E can significantly reduce the muscle damage created by resistive training, and may enhance insulin production by the pancreas.
While the researchers doubt that vitamin E has a direct effect on pancreatic insulin release, they theorize that its ability to stabilize the membrane may enhance the release mechanism. No data exists yet to support the hypothesis, but it may be possible that vitamin E speeds the interaction between insulin storage vesicles and the plasmalemma of the beta cells. It is also possible that vitamin E makes the beta cell of the pancreas more sensitive to glucose. Either way, says Dr. Craig, insulin levels are elevated, which is important to non-insulin dependent diabetes mellitus (NIDDM) patients who have a decreased sensitivity to insulin. Prior research has shown improved insulin responses in NIDDM patients exposed to a single bout of weight training. Further research on the effects of vitamin E in diabetic subjects is planned.
From an athletic standpoint, Dr. Craig's research data suggests that the disposal of post-exercise carbohydrate could be faster in an athlete taking vitamin E. This would be a great advantage to athletes trying to replenish post-exercise glycogen levels, and would be important for athletes who have to compete over several days of competition.
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Physiology research in exercise has been responsible for demonstrating that women are physiologically capable of running the marathon without the event being detrimental to their health and well being; the necessity of competing in a hydrated state, seeking frequent fluid replacement during endurance events; being acclimatized to heat before competition; scheduling competition in the early or late hours of the day; and providing fluids that contain a fixed concentration of glucose during the long distance events; the advantages to athletes -- particularly swimmers -- of tapering in their training before competition; the importance of the specificity concept in athletic training schedules and the acceptance by coaches of team sports (basketball and volleyball, among others) that specific power and strength training principles must be followed to enhance performance. The American Physiological Society is devoted to fostering scientific research, education, and the dissemination of scientific information. By providing a spectrum of physiological information, the Society plays a significant role in the progress of science and the advancement of knowledge.
Editor's Note: For further information or to schedule an interview with Dr. Craig, contact Donna Krupa at 703.527.7357; cell: 703.967.2751; or at [email protected]; or visit the APS website at www.faseb.org/aps.
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