A Biomechanical Comparison of Back And Front Squats In Healthy Trained Individuals

A Biomechanical Comparison of Back And Front Squats
A Biomechanical Comparison of Back And Front Squats

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The squat is a widely used exercise that activates the largest, most powerful muscles in the body and may be the greatest test of lower-body strength. As most activities of daily life require the coordinated contraction of several muscle groups at once, squats are considered one of the most functional and efficient weight-bearing exercises whether an individual’s goals are sport specific or are for an increased quality of life.

Although both squats effectively work the lower back, hip, and leg muscles, the back squat is typically performed by athletes more often than the front squat. Why so? And which is less dangerous for you?

Differences in Squats

The back squat involves positioning the barbell across the shoulders on the trapezius, slightly above the posterior aspect of the deltoids, then allowing the hips and knees to slowly flex until the thighs are parallel to the floor. A heavy emphasis on keeping the back flat, heels on the floor and that the knees are aligned over the feet is evident during the back squat.

As compared to the front squat, which requires an individual to place the barbell across their anterior deltoids and fully flexing the elbows to position the upper arms parallel to the floor.

Both techniques possess similarities in execution, however, it is disparity of each methods ability to protect and isolate different muscle groups that is most intriguing.

Experimental Approach to the Problem

A repeated-measures, within-subjects design was used to determine which squat variation places the least force and torque on the knee and to examine the effects of front and back squats on primary as well as secondary and stabilizing muscle groups.


Fifteen healthy individuals (nine men, six women), who had over 12 months experience of performing both squat variations at least once a week who averaged 22.1 ± 3.6 years of age, participated in this study. All of those who participated were free from orthopedic injuries.


Six pairs of Ag/AgCl surface electromyographic (EMG) electrodes were placed over the belly of each muscle of interest to assess the health of muscles and the nerve cells that control them (motor neurons) when performing each 1RM squat after the adequate warm up sessions.

Once subjects were warmed up, they were fitted with black, tight-fitting shorts and were asked to remove their shoes and socks. At this point, a series of anthropometric measures including body mass, height, thigh length and pelvic width were taken to eliminate interrater variability.


Overall, the statistical differences in the net compressive/ tensile force at the knee between the two squats were quite significant. Specifically, the back squat recorded a higher average maximum compressive measure on the subject’s knee (11.0 ± 2.3 N·kg−1) than the front squat (9.3 ± 1.5 N·kg−1). Adversely, the average maximum anterior/posterior forces at the knee did not vary between the squats, as the back squat averaged (−5.0 ± 1.5 N·kg−1) sheer force and (−4.9 ± 1.3 N·kg−1) for the front squat.

Data also revealed that muscle activity was relatively minimal during the descent phase and reached maximal levels throughout the ascent phase, yet the bar position did not influence this muscle activity of examined groups.


Interestingly, the two squat variations were similar in some ways and quite different in others. For example, net shear (anterior/posterior) forces at the knee did not vary with bar position, whereas net compressive forces and extensor moments increased for the back squat.

This study suggest the back squat resulted in higher net compressive (proximal/distal) forces on the knee than the front squat. Signifying that front squats could be advantageous for people with knee problems such as ligament and meniscus tears, and for general long-term joint health. Front squats could also be useful for individuals with shoulder problems that limit their range of motion, making it hard to grip the bar during the regular back squat.

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