thats when theyre mostly used.. and as grav said, the best way to see results is to use good form, you'll end up like alot of the idiots you see in the gym, they swing high numbers around like they think they know what theyre doing, but theyre barely using the target muscle group(s) and they won't see the results they want , if they even see any at all. using good form puts the maximum strain on the targeted muscle which leads to better results in strength and size!