1.  Poor hormonal profile.  Running results in a huge production of the stress hormone cortisol, which is a catabolic hormone.  This means that it breaks down muscle and lifting will only help maintain LBM and metabolism.  The general belief that lifting weights will make you look like the guy on “Flex” is extremely incorrect, especially in the hormone category.  Those gentlemen are hormonally enhanced.

2.  Time.  Getting “bulked up” takes time.  You don’t just lift a few days, and wake up gigantic.

3.  Rep ranges.  Higher repetition ranges prioritize muscle size, lower ranges develop strength.  Sure, it’s possible to get bigger with hard, focused, patient strength training, but with a properly developed system you’ll gain strength without much appreciable size.
4.  Growth is a function of intake.  While it is a bit too simple to say that if you eat more calories than you burn, you’ll gain weight, it’s by and large accurate.  Thus, in pursuit of relative strength an athlete who is eating at maintainence will not have the additontioal fuel to grow to be a flex cover model.

5.  Genetics.  If you’re a natural born runner, your odds of getting “huge” are already dampened on account of your genetics.  Your predominate fiber typing–slow twitch–is not a one that is known for it’s explosive growth potential.  Further, the ectomorphic runner tends to have a screaming metabolic rate, which makes getting the extra nutrition hard to do without significant effort.  This isn’t to say that you can’t get big, but to say that under normal conditions, you won’t.

Food for thought.

Regards,

Carson Boddicker