Earlier experiments in Canada, often described as "elegant," showed that when test subjects were given a drug to boost cardiac output (somewhat like exercise does), and then took the same drug and vitamin C, the increase in cardiac output was much greater. These results were widely interpreted as suggesting that since vitamin C decreased oxidative stress and improved heart performance, perhaps physical performance in exercise might be similarly boosted.
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."
Neither long- nor short-term vitamin C intake boosts exercise capacity
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 se