The preponderance of research to date suggests that exercise-induced reactive oxygen species and nitric oxide are beneficial. These free radicals induce adaptive changes in muscle that lead to greater production of mitochondria and hypertrophy of myofibers [ 17 , 21 , 23 , 24 ]. Exposure of cells to high concentrations of various antioxidant supplements (of which vitamins C and/or E have the most evidence) appears to blunt or block cell signaling and thereby inhibit some favorable physiological and physical adaptations to exercise. However, these adaptations might not prevent improvements in VO 2 max or endurance performance [ 25 ].
The Fitness column last Thursday, about nutritional supplements for exercisers, overstated Dr. Teri M. McCambridge’s role at the American Academy of Pediatrics. She is the chairwoman of its council on sports medicine and fitness, not the chairwoman of the entire academy. The article also referred incorrectly to nitric oxide; although caffeine is often added to supplements that contain it, it is not a caffeine-based stimulant. And a picture caption with the article misidentified the exerciser who begins his morning workout by taking .-Xplode. As the article correctly reported, he is Michael Deutsch not Alex Feintuch, who is shown in the picture.
In the rat pre-and postnatal development study, the NOAEL (no observed adverse effect level) for maternal toxicity was 8 mg/kg/day. Retarded physical development of pups in the absence of maternal effects was observed following maternal exposure to 1 and 8 mg/kg possibly due to vasodilatation and/or secretion of the drug into milk. The number of living pups born to rats exposed pre- and postnatally was reduced at 60 mg/kg/day. Based on the results of the pre- and postnatal study, the developmental NOAEL is less than 1 mg/kg/day. Based on plasma exposures in the rat developmental toxicity study, 1 mg/kg/day in the pregnant rat is estimated to produce total AUC values for unbound vardenafil and its major metabolite comparable to the human AUC at the MRHD of 20 mg.