In regards to the smith machine...
When I started lifting, a few years ago, I was not comfortable with squatting in the rack. It hurt the back of my neck and I thought I'd get hurt. So I stuck with the leg press, and the smith machine. After 6 months I could put up 850 pounds on the 45 degree leg press sled. I thought I had strong quads/glutes.
Then a friend turned me on to squatting with a barbell. Immediately I realized that with the machines I had been neglecting all the stabilizers that you use when you squat with a barbell. I could barely put up 200 for reps. The soreness I got out of free squatting was GREAT, and much more intense than the machines. My progress in terms of strength and quad development increased greatly, as did my lower back strength.
Whats more, my knees stopped hurting. When squatting on the sled or a smith machine, the pressure of the weight would be felt HEAVILY on my knees. It was more evenly divided among knees, calves, back, abs, glutes and quads when squatting with a barbell.
In short: the body was designed to lift weight freely against gravity. If you use it as it was intended, you will see better results.
Squatting is important not just because it hits quads and glutes. It is important because it is a compound exercise. Compound exercises like squatting, bench pressing, and deadlifting cause hormonal secretions that cardio and machines/isolation exercises do not. Namely: testosterone and Human Growth Hormone release. These hormones will benefit all aspects of your physical fitness. You'll get stronger, leaner, and meaner. Which will make you a better rider.
I'm not saying that you won't benefit from any hormonal changes using a machine... but it stands to reason that if compound movements elicit more positive hormonal changes than isolation movements, then the more muscle groups you involve, the more hormonal changes you will see. This is why you rarely see anyone who is serious about resistance training using a machine for squats.
Above all else... squatting a barbell feels GREAT once you're into a routine. No machine can ever give you that feeling of triumph when you make the ugly face and give it all that you've got to get that weight back up that last time before you slam it on the rack. The high from free squatting cannot be beat.
I'd compare the leg press machine or the smith machine versus free squatting, to a stationary bike versus the real deal. It feels that much better.
Last edited by Crunkologist; 10-01-04 at 12:19 PM.