Good Morning's, where you have to bend the knees that much to keep standing. Have to bend the knees almost that much when doing extra heavy bent over BB rows. Chains were used because (probably) the Cam bar would not sit on pins very well or allow the hands to grip..
Chains were used very much back in the 50's before the power rack became popular. Paul Anderson used chains on his squats and presses/jerks. Partial reps were done a lot that way..
Cam bars give a lower center of gravity for lifting (more so than with the weight higher up on the neck/shoulders), seems to be better for power movements. And easier on the shoulders and upper back for heavier squatting/ GM'ings, etc. There are special designed Cam bars for benching also. Gives a better stretch for the full ROM.
