A squat cannot be performed on a Smith machine any more than it can be performed in a small closet with a hamster.
Mark RippetoeA weak man is not as happy as that same man would be if he were strong. This reality is offensive to some people who would like the intellectual or spiritual to take precedence. It is instructive to see what happens to these very people as their squat strength goes up.
Mark RippetoeIf a program of physical activity isn't designed to get you stronger or faster or better conditioned by producing a specific stress to which a specific desirable adaptation can occur, you don't get to call it training. It's just exercise.
Mark RippetoeThere is simply no other exercise, and certainly no machine, that produces the level of central nervous system activity, improved balance and coordination, skeletal loading and bone density enhancement, muscular stimulation and growth, connective tissue stress and strength, psychological demand and toughness, and overall systemic conditioning than the correctly performed full squat.
Mark Rippetoe