Yes, it helps increase testosterone levels which promote overall growth.
A small and transient increase in testosterone has no impact on muscle growth.
In fact on the long run, very rigorous physical exercise (even weightlifting) tends to reduce average testosterone levels somewhat, to which leg training contributes considerably.
What causes growth are mostly growth factors produced locally by the exercised muscle fibers. That's why you do curls and your biceps grow, you do squats and your legs grow. Your legs won't grow from curls and your biceps won't grow from squats.
If the whole idea of the overall anabolic effect of heavy squats had any substance to it then the opposite would also be true - doing heavy upper body compound exercises would also cause your legs to grow. Just look around any gym at the guys who train upper body 6x per week and legs on Christmas to see how well that works for them.
In fact I would say that when you consider the impact that a proper lower body training regimen has on your overall energy output, energy levels and recovery time, one could probably make faster upper body gains by not
post edited by Uriel - 2014/09/29 11:35:58