I read a pretty interesting article on Vitamin C and endurance. This journal has free access after 1 year, so everyone should be able to look if they are so interested. I found this article interesting both because it has to do with a potential downside to dosing up on vitamins and nutrients, and because I do CrossFit, and a possible reason that CrossFit works the way it does is by producing large amounts of reactive oxygen species in your body. I think the experimental design was basically good, but the sample size was pretty small(14). Common occurence. They even checked their assumptions, although I tend to like visual assessments of statistical assumptions, especially when sample sizes are small. It is almost impossible to fail a normality test with a small sample size.
However, being something of a Bayesian, I think one can increase the certainty of the results by including prior information, such as Vitamin C is known to be an anti-oxidant, and part of the way you get stronger and faster is by stressing your body. Thus, I think this is interesting, even though I lack detailed subject knowledge that would allow me to assess the study more comprehensively.