If you've been debating whether or not to try a nutritional supplement, you may be surprised to know that you've already been using one for quite some time -- even if you didn't realize it.

Ask almost any regular exerciser what one of the most effective and widely-used supplement is, and they'll surely tell you it's caffeine. Research shows that drinking a caffeinated beverage prior to a workout can help a person lift more weight and complete more reps. What's more, caffeine -- in particular, coffee -- is one of the main single sources of antioxidants in the American diet, which means that it helps neutralize free radicals as it helps burn fat and improve athletic performance.

There have been over 21,000 studies conducted on the health benefits/detriments of caffeine on the body. And though I obviously focused on a benefit in this post, it's worth knowing that other research indicates that consuming too much caffeine can restrict blood flow during exercise. Clearly this falls into the "detrimental" category. However, in this study, participants consumed 300mg of caffeine, or the equivalent of about three cups of home brew. Therefore, using the results of said study as our guide, if you keep your pre-workout caffeine intake to one cup, you should be just fine.