I would think while on juice, all your body parts would grow faster/bigger if you train harder and heavy. Why are my biceps just not growing for so long. There at 16", well right arm 16.5 and left 16". I think I need to train my biceps more than once a week. What are the best excerises that made your arms really grow and notice changes and for how long? I am starting to do one arm dumbell preacher curls, regular bicep curls and concentration curls.