Efecto de la administración de antioxidantes orales en las adaptaciones al ejercicio físico.
Exercise practitioners often take supplements with antioxidant vitamins, we wanted to test their effect on training efficiency in both rats and humans. The human study was double blind and randomized. We trained 14 subjects for 8 weeks. Five subjects took 1g of vitamin C daily. In the animal study, 36 male Wistar rats were exercised for 3 or 6 weeks. Twelve animals were treated daily with vitamin C (0,24 mg/cm2 of body surface). Training was estimated measuring running capacity to exhaustion (in rats) or increases in VO2max (in persons). The effect of training on muscle mitochondrial biogenesis and antioxidant enzyme expression was also measured. We found that in persons, 8 weeks of training increased VO2max by 22% (p<0.05). However, in the group that took vitamin C the increase was non significant. Untrained rats ran for 100 minutes and after 6 weeks of training they ran for 300 minutes, but the group of rats treated with vitamin C ran for 120 minutes only. We offer a molecular explanation for this, that vitamin C decreases exercise-induced expression of transcription factors involved in mitochondrial biogenesis and of markers of mitochondrial content. It also prevents the increase in the expression of antioxidant enzymes such as manganese superoxide dismutase (Mn-SOD) or glutathione peroxidase (GPx) which occurs after training. Vitamin C supplementation decreases training efficiency in humans and in animals because it prevents cellular adaptations to exercise.