Many squat variations appear to produce high levels of erector spinae muscle activity, although machine squats may be less effective
than free weight squats.
Performing machine squats produces less upper erector spinae muscle activity
than free weight squats.
Not exact matches
The last nail on the coffin comes from a Canadian study which found that
free -
weight squats allow around 43 % more muscular activation
than Smith - machine
squats, which means that
squatting in the Smith machine is literally a waste of your time and energy.
There was one study done on trained lifters which reported that they could lift around 4 % more
weight on the Smith machine
squat variation
than the
free -
weight back
squat, even though the latter burns more calories because of the greater engagement of stabilizer muscles.
Comparing
free weight and machine
squats, while some researchers have reported lower erector spinae muscle activity in the Smith machine
squat than in the
free weight back
squat, with both the same absolute (Anderson and Behm, 2005) and relative (Fletcher and Bagley, 2014) loads, Schwanbeck et al. (2009) found no differences (using the same relative loads).
Comparing
free weight and machine
squats, Anderson and Behm (2005) found no differences between conditions (with the same absolute loads) but Schwanbeck et al. (2009) noted that the
free weight back
squat displayed higher muscle activity
than a Smith machine
squat (with the same relative loads).
In most situations, I would rather have someone perform a
free weight squat than a TRX
squat, for example.
Biomechanically, isometric training with short muscle lengths is actually more similar
than you might realize to partial range of motion training with constant - load,
free weight exercises, like the barbell back
squat.