These two components are different sources of work-out routines in the fitness industry. Each person may dominantly develop either one of the traits and not both. Some runners are born with the muscular endurance while body builders don't have this in their genetic material. Improvements in both could be possible through proper training regimen and the result of each affects the other. One cannot simply have muscular strength without first developing muscular endurance. Simply put, you cannot lift a 100 lb barbell if you are not able to lift a 20 lb barbell repeatedly.