Creatine has been around for over 20 years. Its uses for enhancing strength, size and endurance and the various regimens to get there have been well documented. At this point, secondary effects are being explored- for example, does creatine alter the oxidative stress profile of an athlete? Pecario et al, 2012 tried to answer this question.
This is actually a really good idea since literally millions of people supplement with creatine. Creatine (when consumed with both protein and carbohydrates) has been shown to increase muscle size, ATP-PC endurance, 1RM strength. There is some evidence suggesting increases in testosterone, dihydrotestosterone and IGF-1.
The researchers divided a team of Brazilian handball players into 3 groups; creatine, placebo and no supplementation. All subjects on day 0 and 32 days post-supplementation had blood drawn checking for oxidative stress markers; thiobarbituric acid reactive species, total anti-oxidant species and uric acid. They also completed a fitness assessment consisting of BMI, body fat by skin fold, 1 RM bench press and max reps bench. Training was 3-4 days/week at 75-95% of max values.
Over the course of the study, it was found that the athletes taking the creatine supplementation got stronger (as expected). Their uric acid production increased and their decrease in total anti-oxidant species suggests that creatine supplementation promotes free radical formation. Thus while making an athlete stronger, without supplementing with an anti-oxidant or a proper diet, long-term creatine use could lead to long-term complications as anti-oxidant status is a standard health measure. Consider all the facts while creating your supplement stack.