If you're building strong butt muscles to develop explosive power for your favorite sport or type of recreation, you'll probably find yourself doing functional exercises that mimic the motions of the sport. But if you're trekking to the gym in search of a shapely booty, you might find what you're looking for among the exercise machines that make it possible to isolate the gluteus muscles that give your backside both shape and power.
Tip
Machines such as the leg press, four-way hip and rear kick help build a nice booty. But you don't have to limit yourself — there are free weight and barbell options too.
Meet Your Biggest Butt (Muscle)
Technically, you have three major muscles in your buttocks: The gluteus maximus, gluteus medius and gluteus minimus. Of these three, the gluteus maximus is by far the largest, most powerful and most visible. So whether you're building stronger butt muscles for physical power or for looks, your focus should be on the primary gluteus maximus motions of hip extension and, to a lesser degree, transverse abduction — swinging your thighs outward from a bent hip. Of those motions, hip extension — in other words, straightening a bent hip — is the easiest to do.
Press it Out
A study commissioned by the American Council on Exercise evaluated seven exercises for efficacy against traditional squats, which have long been considered the gold standard for developing your butt muscles. Three exercise machines were included in the comparison. Of these, two variations of the leg press machine actually came in the lowest in muscle recruitment — but because these machines are so common and relatively easy to use correctly, they're still worth mentioning.
Go Four Ways
The other exercise machine evaluated in the ACE-commissioned study, the four-way hip extension machine, was a clear standout. While this machine is less common than a leg press, if you can find it you'll get a great butt workout.
Aside from the name itself, look for a machine with some sort of a handrail or bar you hold onto for stability, and a pivoting foam roll that you stand next to and move in one of four ways: lifting your knee up and forward (with the foam roller on your thigh); swinging your leg inward across your body, also known as adduction, with the foam roller as resistance; swinging your leg outward from your midline, also known as abduction; and swinging your leg straight back from the hip with the foam roller against the back of your thigh. Of these motions, the latter two are most effective for your glutes.
Kick it Back
Although it wasn't evaluated in the ACE study, the mule kick/rear kick machine isolates the glutes for a very effective butt exercise. This machine has a padded shelf you drape your upper body over, handlebars you hold onto for stability and a broad plate that you plant one foot at a time on and press back behind you, much like a mule would kick out.
Extend Your Back
Another very common exercise "machine" you'll see at the gym — although it doesn't actually have any moving parts — is the back extension or hyperextension bench. On this apparatus, you lean forward against a hip pad and then hinge forward from the hips. Although this machine does work the stabilizing muscles in your back, the primary effort of reversing that hinge motion and returning to your starting position comes from your glutes.
Tip
They're not as common as they used to be, but sometimes you'll still see a version of the back extension machine that does have moving parts. In that case, you sit down in a "chair" with a hinged back and use the power of your hips and back to press the back of the chair backward.
Use a Barbell
One of the most popular glute exercises in recent years doesn't involve an exercise machine at all. Instead, it uses a barbell for resistance. To do hip thrusts, sit on the floor with your back against the long side of a flat weight bench. Lean your shoulders on the top of the bench; plant your flat feet on the floor with your knees bent, and keep your core tight as you thrust your hips up to the ceiling. Once you've mastered the basic motion, add a light barbell for resistance, holding it against the front of your hips.
Add More for Variety
Barbell hip thrusts aren't the only effective glute exercises you can do with free weights. In fact, the study conducted by ACE showed a handful of free-weight exercises — single-leg squats, step-ups, quadruped hip extensions and lunges — to be excellent alternatives to traditional squats. And, of course, you can always do the squats themselves, although like most of the free-weight exercises just mentioned, they require careful attention to your form to prevent injury.
Tip
As you're getting used to these exercises, sets of eight to 12 repetitions make a nice, conservative target that you can then fine-tune to suit your needs.