Quadriceps: what they do, and what trains them

Where they are, and what they move

The quadriceps are the block of muscle on the front of your thigh, running from the hip down to the kneecap. Four bellies share one tendon: the rectus femoris in the middle, the vastus lateralis on the outside, the vastus medialis on the inside, and the vastus intermedius underneath the rectus. All four pull on the same tendon, which wraps the kneecap and attaches below the knee.

Three of the four cross only the knee, so all they can do is straighten it. The rectus femoris is the exception: it starts on the pelvis rather than the thigh bone, so it crosses the hip as well and bends the hip in addition to straightening the knee. That one anatomical detail explains most of the difference between the exercises below — a movement that keeps your hip bent the whole time asks something different of the rectus femoris than one that opens the hip as you stand up.

A fifth belly, the tensor of the vastus intermedius, was described in 2016 and is not in older textbooks. We list it because it is part of the current anatomical picture, and we have not read the paper — see the sources at the foot of this page, which say for each one how far we actually got.

At a glance

What Kiptly’s own exercise catalogue says about this muscle. These numbers are generated from the same data the app uses to fill your workout — nothing here is a marketing figure, and nothing is typed by hand.

What actually trains them

Almost everything in the strength list is some form of squat, lunge or press with the feet on a platform. That is not a limitation of the catalogue; it is what the muscle does. Straightening a loaded knee is the whole job, and there are only so many ways to arrange a body around it.

The arrangements differ in where the load sits and how much the hip contributes. A back squat, a front squat and a leg press all straighten the knee under load, but the trunk angle and the bar position change how much of the work the hips take and how far the knee travels. Single-leg variants — lunges, split squats, step-ups — put one leg under the whole load, which is a different demand at the same absolute weight.

Only two movements in the whole strength list isolate the knee extensors rather than sharing the work with the hips and the trunk. Everything else is compound by the catalogue’s own classification, which is the honest reason a quadriceps session and a leg session are usually the same session.

Exercises in the app

Every strength exercise in the app that names the quadriceps as a primary muscle, with the equipment it needs and how the catalogue grades it. Grouped by equipment, largest group first — the app does not rank movements and neither does this table.

Training them with no equipment

A meaningful part of the strength list needs nothing but your own body, and it progresses through leverage rather than load: both legs, then one leg with help, then one leg without. The pistol and shrimp families in the table are that progression written out, and between them they span every difficulty grade the catalogue has — from the assisted pistol squat at the bottom to the unassisted shrimp squat at the top — without a single plate.

Kiptly records these the same way it records a loaded set. Bodyweight movements get a weight of their own — a share of your body mass that depends on the exercise — so a set of pistol squats and a set of leg presses land in the same volume total instead of one of them counting as zero. How that share is worked out is a question for the methodology section rather than this page.

Trained alongside

Which other muscles the same exercises name, primary or secondary. This is a map of what you cannot help training when you train this one — read it as overlap, not as a plan.