I'm doing thidideau's OVT regimen. He has me doing bb curls w/alternating db curls...then preachers w/hammer curls. The hammer curls do not hurt my forarms, but the regular curls make my arms hurt when I release my grip on the bar. Is there something I need to modify with form, or can I substitute another set of exercises? Thanks for the help. What can I do to strengthen whatever I need to, to remedy this problem?