Vitamin C has no positive effect on exercise performance

• -- Orange juice or other sources of vitamin C (ascorbic acid), may (or may not) benefit you in terms of health and exercise, but contrary to what many people thought previously, ascorbic acid doesn't seem to help physical exercise performance.
• And in terms of such endurance exercise as running, walking or cycling, whereas vitamin C reduces physiological "oxidative stress," that reduction didn't help performance for either men or women, whether they were in their 20s or 60s.
• To study this effect in a "real life" exercise setting, physiologists at the University of Colorado, Boulder, gave vitamin C to a group of young (23 years old) and older (61 years old) adults prior to their performing exhaustive exercise on a treadmill.
• The researchers predicted that "acute administration of ascorbic acid might improve/restore maximal aerobic capacity (MAC) and maximal cardiac output (MCO) in the sedentary older adults, thus creating the possibility that longer-term ascorbic acid supplementation could be used therapeutically to sustain the improvement."
• But reporting in the online edition of the Journal of Applied Physiology, the Colorado physiologists said "the age-associated decline in (MAC and MCO) is unaffected by acute or chronic (30-day) administration of moderate daily ascorbic acid supplementation" for either men or women.
• The lead researcher, Christopher Bell, noted: "We did see a decrease in oxidative stress with large doses of vitamin C, but this decrease didn't improve aerobic abilities either for younger or older subjects."
• So in order to set the stage for the greatest possible effect, "we used sedentary older people because we wanted the highest level of oxidative stress as possible.
• But they were still healthy," Bell noted, and some earlier studies had "suggested that antioxidant administration may only prove to be beneficial for populations with elevated baseline oxidative stress such as vascular disease patients, smokers or older adults."