Abstract:
Purpose. The purpose of this
study was to compare muscle recruitment during a leg press and a traditional
squat lift. Subjects. Two groups of subjects were used for this
study. Group 1 consisted of ten, healthy, normal males. Group 2 consisted of sixteen, healthy,
trained, male athletes. Methods. Surface electromyographic (EMG) activity was
recorded from the erector spinae (ES), gluteus maximus (GM), vastus lateralis
(VL), and biceps femoris (BF) muscles.
The exercises performed were a leg press (Plyo-Press), and a traditional
squat lift. Each subject in Group 1
performed three repetitions of each exercise using a weight equivalent to their
body weight (155 to 265 lbs). Each
subject in Group 2 performed three repetitions of each exercise using a weight
equivalent to 80% of their 1 RM (225 to 600 lbs). Results. In the trained
group (Group 2), the squat exercise elicited significantly more EMG activity
than did the leg press in the ES, GM and BF.
There was no significant difference in the VL activity between the two
exercises. In the normal group (Group
1), the results were similar in that the squat exercise also elicited
significantly more EMG activity in the ES, GM and BF. In the normal group there was no significant difference in the VL
activity between the two exercises.
Conclusion. In this study, the
leg press provided the same level of muscle recruitment in the VL as did the
squat exercise. However, the leg press
did not recruit the ES, GM or BF to the
extent that the squat exercise did. Therefore, we hypothesize that the leg
press machine may be better for individuals who want to specifically strengthen
their quadriceps musculature, but reduce the strain on the low back that may be
caused by the excessive activity of the ES musculature.
Purpose:
It has been
suggested that traditional squat lifting with free weights may put strain on
the low back because of the increased muscle activity in the low back
musculature that occurs during the lift.
Furthermore, it has been proposed that the leg press will activate the
quadriceps muscles to the same extent as the squat lift without excessive
activation of the low back musculature.
However, there is little research to support these claims. Therefore, the purpose of this study was to
compare muscle recruitment during a leg press and a traditional squat lift. It
has been suggested that traditional squat lifting with free weights may put
strain on the low back because of the increased muscle activity in the low back
musculature that occurs during the lift.
Furthermore, it has been proposed that the leg press will activate the
quadriceps muscles to the same extent as the squat lift without excessive
activation of the low back musculature.
However, there is little research to support these claims. Therefore, the purpose of this study was to
compare muscle recruitment during a leg press and a traditional squat lift.
Methods:
Subjects.
Two groups of subjects were used for this study. Group 1 consisted of
ten, healthy, normal males. Group 2
consisted of sixteen, healthy, trained, male athletes. The subjects in Group 1 were chosen because
they were able to squat lift a weight equivalent to 75% of their body
weight. The subjects in Group 2 were
chosen because they were able to squat lift a weight equivalent to 80% of their
1 RM. Instrumentation. The EMG data was recorded using the Noraxon
Telemyo8 transmitter/receiver and analyzed using the MyoSoft software
package. Procedure. Surface electromyographic (EMG) activity was
recorded from the erector spinae (ES), gluteus maximus (GM), vastus lateralis
(VL), and biceps femoris (BF) muscles. The exercises performed were: 1) a leg press using the Plyo-Press® device,
and 2) a traditional squat lift using free weights. Each subject in Group 1 performed three repetitions of each
exercise using a weight equivalent to their body weight (155 to 265 lbs). Each subject in Group 2 performed three
repetitions of each exercise using a weight equivalent to 80% of their 1 RM
(225 to 600 lbs). Data Analysis. The EMG activity was normalized based on a
maximal voluntary contraction (MVC) for each muscle. A comparison was made of the normalized EMG values, recorded for
each muscle, during the two exercises using paired t-tests. Alpha levels of 0.05 were used to test for
significance.
Figure
1. Subject on the PlyPress.
Results:
In the trained
group (Group 2), the squat exercise elicited significantly more EMG activity
than did the leg press in the ES, GM and BF.
However, there was no significant difference in the VL activity between
the two exercises (Table 1). In the
normal group (Group 1), the results were similar in that the squat exercise
also elicited significantly more EMG activity in the ES, GM and BF (Table
2). As with the trained group, there
was no significant difference in the VL activity between the two
exercises.
Figure 2. PlyoPress versus squat exercise.
Figure 3. Leg press versus squat exercise.
CONCLUSION:
The
leg press provides the same level of muscle recruitment in the VL as does a
squat exercise. However, the leg press
does not recruit the ES, GM or BF to the extent that the squat exercise does.
Therefore, we hypothesize that the leg press machine may be better for
individuals who want to specifically strengthen their quadriceps musculature,
but reduce possible strain on the low back that may be caused by the excessive
activity of the ES musculature.
However, if the training is aimed at training the ES, GM or BF; then the
squat lift may provide a better training stimulus.