I know just from experience and logic alone that barbell squats are king and smith squats are peasant, and I'm trying to get my brother-in-law to do Starting Strength but he keeps insisting that the smith machine will give him just as much growth. I'm trying to explain to him that the smith bar is bound in a certain environment only traveling up and down and so does not require you to stabilize it with your back/core, but he is asking me for "research" or hard evidence or something that the barbell squat is that much better to do. I'm not educated enough in the subject to just bust out some scientific talk, the best I can say is what I just said above, that smith squats basically remove half of the workout due to not requiring lower back stabilization. I really just want him to benefit from this great exercise but he's being stubborn =/
Anyone here that can help me out, perhaps some scientific sources?
The best I found was here:
A study in the December 2009 issue of the Journal of Strength Conditioning Research illustrated that when compared with the Smith machine squat, a free-weight squat activated muscles an average of 43 percent more. The study used elctromyography to measure muscle activation in six healthy people.