Bloke I go running with (Lunch time in work) has a heart rate monitor.
I'm not sure what he uses it for (or he doesn't really).
I've googled that your heart rate should be about 75% of max for best cardio improvement other than that no idea what the other % are equal too and how these equate to mma, grappling and the best way to use them. Or if they are worth it at all?
Seen them on TUF and just thinking.