Working legs to trick the brain?

[fis...@hotmail.com]

I"m a 46 yr old male looking to build up my upper body (arms/chest)
and I've heard from a couple of sources that to maximize the results I
will also need to build (muscle mass) up my legs. The theory I'm told
is that it's as if the legs have to signal the brain that they can
support more weight (muscle mass) on the upper body - otherwise you
will be fighting your brain's attempt to keep things in balance.

I also do a lot of running and was going to split my week up with 3
days running 3 days of upper body workouts 1 day rest. This idea of
having to build muscle mass on my legs is going to force me to give
something up- which i'd rather not do.

Can anyone tell me if there is any truth to this?

Tks
Steve