I'm responding, briefly, to your message re Smith machine
I read your rough draft. I dislike the Smith machine squat
for several reasons. I go into them in detail in my books. In
a nutshell, three of the reasons are..
1. The machine locks the body into the machine's groove, and
prevents the body from determining its groove.
2. If you stand with your feet pretty much underneath the
bar, the knee flexion will be exaggerated, and stress there exaggerated
3. If you put your feet forward, to reduce knee flexion, the
lower back is put in a weak position, with rounding of the lower
back likely. In addition, there is additional stress on the knees
as the feet want to slide forward but don't because of the friction
from the floor surface.
All in all, the Smith machine squat may give an illusion of
safety relative to the barbell squat, but in reality it's a bad
exercise. Sure there are degrees of "bad" depending
on the specific form used, and the individual, but it's still
a bad exercise. Rather than try to minimize the problems with
a bad exercise, why not just stick to exercises that have far
better potential? Of course, even the "safe" alternatives
can be ruinous if not done properly, but best to stick with movements
that have good potential.
Thank you for your amazing exrx web site. For the Smith squat
exercise, you correctly reported that:
"First, there is no clinical evidence or research
data whether published or not, of which I am aware (which of
course may simply mean I haven't come across it yet) that would
lead one to conclude (according to the accepted statistical methods
for the treatment of data to establish a correlation or causal
relationship) that squats performed on a Smith-machine apparatus
pose any inherent danger to either the knees or the spine when
performed correctly. If anyone can offer such evidence I would
greatly (and sincerely) appreciate him or her sharing it, or
letting me know where I can acquire it. Alternatively I would
also be interested in discussing any Biomechanical models that
he or she may have used to arrive at this conclusion. Anecdotal
accounts, opinion, and conjecture, regardless of the source or
the forum, do not constitute evidence."
I'm now glad to let you know that I (and my co-workers) have
recently published a paper on this subject:
This work was also inspired by the discussion reported on
your web site at the link http://www.exrx.net/Kinesiology/SmithSquat1.html
For this reason this link was cited in the paper.
Prof. Andrea Biscarini