You’ve probably heard that dark chocolate can help keep you healthy thanks to its hefty dose of antioxidants. While the antioxidants may increase blood circulation, and tests in mice show one specific cocoa-derived antioxidant, epicatechin, triggered growth of new capillaries and mitochondria , allowing the critters to exercise longer before pooping out, tests in humans have been mixed.
Dark chocolate seems to reduce oxidative stress related to exercise as well as provide some other benefits, but studies seem to show no effect on performance. Eating dark chocolate before or after exercise certainly won’t hurt, but I think it’s premature to recommend it across the board. If you like chocolate, however, by all means treat yourself to a few squares a day. Pick one containing 70 to 80 percent cacao to get the most antioxidant bang for your buck.
Based on my experience like I said before 70-80 percent cacao is an excellent choice. I usually take in a full bar of dark chocolate after a long run of 11-15 miles or even a speed workout. I recommend Ghirardelli with sea salt.