There’s a reason squats are the “king” of strength-training exercises. Squats are a compound exercise, an exercise that works all of the major muscles in the lower body, including the hamstrings, quadriceps, and glutes. Plus, squats also activate the hip flexors and core. Who doesn’t want an exercise that targets lots of muscle groups at once? The more muscle groups you work simultaneously, the more calories you burn. No wonder a balanced training program almost always includes squats!
Squats really aren’t a single exercise. You can vary the stimulus on your lower body by changing your foot position, altering the depth to which you descend, changing the resistance or the type of resistance you use – dumbbells or barbells. One of the most popular ways to perform this exercise is to hold a barbell as you squat – but there’s more than one way to do that too. You can place the barbell in front of you, across your clavicles and shoulders, or behind you, on your upper back. The former is called a front squat while the latter is a back squat.
Back Squats vs. Front Squats: Is One More Effective Than the Other?
Both ways of squatting work multiple muscles in the lower body and get the job done effectively – but there are slight differences between the two approaches. A study using EMG to measure muscle activation during both types of squats failed to show statistically significant differences in activation of the quadriceps, hamstrings, back, and glutes using each approach. However, the number of people in the study was small and there was a suggestion of differences between the approaches that might not show up unless you tested a larger number of people.
What were these potential differences? The back squat seems to place slightly more emphasis on the hamstrings and less on the quadriceps relative to the front squat. In contrast, front squats activate the muscles of the erector spinae in the back more. So, you might get a bit more emphasis on the hamstrings when you back squat and slightly more on the quadriceps when you front squat.
What about Stress on Your Knees?
Another concern about squatting, especially deep squats, is the stress it places on the knees. The knees are subject to two types of stress: shearing forces and compressive forces. Shearing forces are magnified when you do leg extensions where you extend your legs against resistance. Shearing forces are dominant with leg extension because it’s an open-chain exercise, meaning your feet don’t touch the floor. As you extend your legs against resistance, the knees shift a bit and shearing forces increase. These shear forces place stress on the ligaments that support the knee, especially the anterior cruciate ligament, or ACL. You also experience some shearing force when you squat and your knees move forward toward your toes. You can limit shearing forces by keeping your knees in line with your ankles when you do a squat.
In contrast, compressive forces on the knees are downward forces that come into play when squatting. When you squat, compressive forces increase as you descend but shearing forces decrease as you drop below 30 degrees. It’s the cartilage in your knees that help absorb compressive forces when you squat. However, healthy knees are usually able to handle the degree of compression you experience when you squat, even when you do a deep one. What’s more, because shearing forces decrease as you squat deeper, you’re actually placing LESS stress on the ligaments that support your knees, including your ACL. That’s why squats, even deep squats, are a safer exercise for your knees than leg extensions where shearing forces are high.
What about the back squat versus front squats? Biomechanical data shows that compressive forces are higher on the knees with the back squat relative to the front squat. However, shearing forces are relatively low with both squat variations. Another advantage of front squats over back squats is your body stays in a more upright position when the bar is in front of you. This reduces the degree to which your spine flexes during the movement. So, front squats may be a better alternative if you have knee arthritis, an old knee injury, or back problems. However, front squats require a greater degree of flexibility than back squats – and with all squats it’s important to use good form to maximize the benefits and avoid injury.
In addition, it’s harder to cheat when you do front squats as you have to keep your shoulders and torso upright to hold the bar. With back squats, people often cheat by leaning their body forward to help move the barbell up. However, leaning forward also flexes your spine more and increases the risk of back injury.
The Bottom Line
Both back squats and front squats activate the major muscles in the lower body, although back squats are a bit better at working the hamstrings while front squats are slightly more quadriceps focused. The most important difference is the impact each has on the knees and back. Front squats reduce compressive forces on the knees and result in less compression of the lumbar spine. That’s something to consider if you have knee or lower back issues.
Assuming you don’t have knee or back issues, why not do both front and back squats? You’ll slightly change the way you work the muscles in the lower body and provide a varying stimulus that may enhance growth and strength gains. Whichever type you do, make sure you always use good form. That’s true of any exercise!
BreakingMuscle.com. “Front Squat Versus Back Squat: Which One Is Best for You?”
PrecisionNutrition.com “Research Review: Front or back squats”
Proc Inst Mech Eng H. 2012 Feb; 226(2): 95–102.doi: 10.1177/0954411911433372.
A Biomechanical Comparison of Back and Front Squats in Healthy, Trained Individuals. Jonathan C. Gullett, Mark D. Tillman, Gregory M. Gutierrez, and John W. Chow.
J Strength Cond Res. 2009 Jan;23(1):284-92. doi: 10.1519/JSC.0b013e31818546bb.
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