Hmmmmmmmmmmmmmmmm

You've got to be kiddin', right?!

Muscles harden and prevent bones from growing?
You seriously don't believe that muscles can be harder than bones, or do you? Well, unless you're a corpse in the midst of rigor mortis.

Resistance exercise stimulates your body to secrete growth hormones (GH). GH, like what its name says, makes you grow (taller [if you're still in puberty] and bigger)

If that doesn't make you taller [if you're still in puberty], I don't know what will.

And your sisters didn't pay attention during science class, did they? =P