Mike Mentzer explains the need to go into the ‘pain zone’ for muscular growth. He also provides guidance on diet, mental state, intensity, duration and injury prevention when training in this state.Source: Joe Weider’s Muscle (May 1980) Page #92 - Joe Weider's Muscle (May 1980) Page #93 - Joe Weider's Muscle (May 1980) Page #150 - Joe Weider's Muscle (May 1980) Page #151 - Joe Weider's Muscle (May 1980)