Become a Personal Trainer
What Muscles Work In A Lunge, And How To Work It Out For Any Exercise
From the FASTER syllabus: this article is taught in full in The honest route from scratch to qualified →
In short: A lunge works the quadriceps at the front knee, with the gluteus maximus and hamstrings at the front hip, the same prime movers a squat uses. The adductors and the trailing leg's hip flexors assist, and the gluteus medius works harder here than in a squat, because a lunge only has one foot on the ground at a time to keep the pelvis level. The four steps that produce that answer are: decide where the force is acting, find the muscles working directly against it, find the muscles assisting, then find the muscles supporting the joint — the same four steps that answered the same question about a squat.
What muscles work in a lunge
The quadriceps at the front knee. The gluteus maximus and hamstrings at the front hip. The adductors assisting, the trailing leg's hip flexors and quadriceps controlling how the back knee lowers, and the gluteus medius working harder than it would in a squat, because a lunge only ever has one foot on the ground to keep the pelvis level.
That is the answer. The useful part, again, is that it came from a method rather than a memorised list, and the same method works on whatever a client is doing next.
The same four steps as the squat, because they work on anything
A recent post here ran this method on a squat. One of the things you learn on our CIMSPA-recognised personal training course is that the method does not change from exercise to exercise, only the answer does:
- Decide where the force is acting on the body
- Identify which muscles work directly against that force (muscles that lengthen are easiest to see)
- Identify which secondary muscles assist that movement
- Identify which muscles would support that joint / movement
Run it on a lunge.
One, where is the force acting? Straight down through the body, the same as a squat, but now split across a staggered stance rather than shared evenly between two feet under the hips.
Two, what works directly against it? The front leg takes most of it. Going down, the front knee bends and the front hip folds, so the quadriceps lengthen at the knee and the gluteus maximus and hamstrings lengthen at the hip, under load. Same prime movers a squat uses, doing the job through one leg instead of two.
Three, what assists? The adductors on the front leg, pulling it back toward the midline on the way up, and on the trailing leg, the hip flexors and quadriceps controlling how far and how fast that back knee drops.
Four, what supports? The erector spinae, holding the spine over a base that is now longer and narrower than a squat's. And the gluteus medius, doing more work here than anywhere in a squat, because a squat has two feet sharing the job of keeping the pelvis level and a lunge only ever has one.
Why that fourth answer is worth having
A trainer who only knows "lunges work the legs" has nothing to say when a client feels it more on the outside of one hip than the other. A trainer who has run the four steps knows that is very likely the gluteus medius, doing the extra stabilising job a lunge asks of it and a squat mostly does not, and can say so plainly instead of guessing.
Point it at anything
A step-up. A single-leg deadlift. Any exercise with one foot doing more of the work than the other asks the same fourth question, and the answer is usually the same muscle group doing a bigger job than it does standing on two feet.
What to do next
The whole route from no qualification to working trainer is set out at become a personal trainer. It sets out what Level 2 and Level 3 contain, what it costs, and how long it takes. The price is on the page, there are no sales calls, and free lifetime return access is included, so the anatomy unit is still there the week a client asks about a hip you have not thought about since the exam.
The anatomy unit itself sits in Level 3 Personal Trainer, and in the Certified PT Bundle at £1,500 alongside Level 2 and Movement Trainer.
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You just read one answer. The course is all of them.
The honest route from scratch to qualified — taught by the people who wrote it, with free return access for life. The price is on the page, payment plans at checkout, no sales calls.
Also worth a look: Level 3 Personal Trainer — the anatomy unit this comes from.
See what the course covers →Frequently asked
Why does a lunge need a different muscle than a squat if the four steps are the same?
It mostly doesn't — the front leg is doing the same job a squat asks of both legs together. The difference the steps turn up is the gluteus medius, working harder to hold the pelvis level because only one foot is on the ground.
Does this method work on exercises that aren't lower body?
Yes. The same four steps answer the question for a row, a press-up or a carry — decide where the force acts, then find the muscles working against it, assisting it, and supporting the joint.
Does finishing the course get me PT Manager?
Yes. PT Manager opens the moment you sign up with FASTER, and adding real clients unlocks once you pass a course.
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