Many people who are seriously into weight training shy away from doing cardio exercise because they think that it will eat away at their hard won muscle mass. While there is a valid concern for those thinking of running a long distance marathon, most of these fears are unwarranted. Basically, the concern is that as you are running, the body may run short of fuel in the bloodstream for immediate use. Although the body has a mechanism for replenishing energy by breaking down fat deposits, this doesn