So many people at the gym are performing both front squats and back squats, without ever really understanding the difference. How are they different? What muscles do they elicit? While all squats generally elicit the same muscles, the different lies in which are fired more during which movement. The muscles of squat we will investigate include:
- glute max
- Semimembranosus (Hamstring muscle #1)
- Semitendinosus (Hamstring muscle #2)
- Bicep Femoris (Hamstring muscle #3)
- Rectus Femoris (Quadricep muscle #1)
- Vastus Medialis (Quadricep muscle #2)
- Vastus Lateralis (Quadricep muscle #3)
- Vastus Intermedius (Quadricep muscle #4)
- Abdominal Muscles (Core)
What Does Research Say about Front Squats and Back Squats?
An EMG (electromyography) based study published in 2015, aimed to differentiate the front squat from the back squat based on the excitation of the primary squat muscles. Not only did the study test the back squat against the front squat, but it also tested different phases of the squats. It tested the descending (going down) phase, the isometric (pause at bottom) portion, and the ascending (or going up) phase.
Here were the important findings:
During the isometric (pause at bottom) phase of the back squat:
- All the muscles activated nearly identically (except one muscle) to the front squat.
During the ascending (standing up) portion of the back squat:
- the bicep femoris and semitendinosus (two hamstring muscles) and the glute max had far more activation in the back squat.
During the isometric (pause at bottom) phase of the front squat:
- the vastus medialis (quadricep muscle) fired more in the front squat than the back squat. This was the only muscle that activated differently during the isometric phase of both squats.
During the ascending (standing up) portion of the front squat:
- The same muscle, the vastus medialis was activated much more than the back squat.
- Overall, all the muscles were more active than they were in the descending (going down) portion of the front squat. Indicating all the muscles worked much harder coming up than going down in the front squat.
So, What does this mean?
To put it simply, this research shows that the back squat works the glutes and the hamstrings much more than front squats. Yet, front squats are better at targeting the quadricep muscles. This is an important distinction between the two squats.
The research also noted that back squats had far greater “trunk lean” than front squats. This means that front squats may be eliciting more trunk extensors, and core musculature.
How can we use Front Squats and Back squats in Physical therapy?
There is large debate about the practicality of squatting, and whether it should be avoided altogether, modified (in the depth), or implemented fully into rehabilitation. But one thing remains: squatting is one of the most fundamental and widely practiced exercises. Being able to adjust form while in therapy may be able to prevent further or future injury for many athletic patients.
Beyond prevention, squatting in therapy can be a great tool to target areas of weakness that patients may be experiencing. Patients with glute or hamstring weakness can benefit from a multi-joint exercise like the back squat. Since, the back squat works on concentric control of of the glute max and hamstrings. While patients that suffer from quad weakness (like acl reconstructions) or core/back extensor weakness (lumbar back patients) may benefit from front squats.
Keep in mind, it takes a trained professional to know what cases (and when in their rehabilitation program) it is appropriate to implement a squat. And in some cases, it may not be appropriate at all. For those that are healthy, knowing the differences in muscle activation can be a great way to vary your leg day targets!