I would say that depends not only on the smith but how you use it, the smiths at my gym the bar isnt straight up and down but travels at an angle which means as you go down the bar moves forward ans you bend at the waist very much like a normal aquat. Granted the smith is not ideal, however if you need to use it do to physical limitations such as injuries and what not it sure beats the hell out of leg presses or other machines since you still get to use the back and whole body, only downside is you dont bring the muscles to stabalize for balance, but it can still allow you to develope a decent set of wheels.Burgboy said:Going real heavy on the Smith is rough on the knees bro....the angle will force your knees past your toes....if you use proper form when doing "regular" squats its like your stiing in a chair and your knees are well behind your toes.