Hack Squat
Credit: Eliza Snow / Getty Images

The hack squat uses a fixed motion machine to isolate your quads and hamstrings. It's a great way to improve the size and strength in your legs, and mix up your routine if you're bored or hit a plateau with leg presses and barbell squats. If you're using the machine correctly, it can be easier on your lower back than those traditional exercises, too. Here are three tips to make sure you nail the movement.

Prime your muscles
This is a given before doing any weight-lifting move, but especially when using machines that zero in on muscle groups: Three to five minutes of foam rolling your hip flexors, quads, and hamstrings to release any mobility-reducing knots in your muscles is enough. (You'll be able to squat deeper, and rebound faster, promise.)

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Go light on the plates
At first, that is. The position is going to feel strange – you're leaning back at a 45-degree angle – and will take some getting used to; you don't want that to happen while you've got your hack squat's one rep max on the bar. (That funky position is also the hack squat's advantage – it's what allows you to target your quads and hammies.) Add 10 to 20 percent more weight for each set until you're comfortable at your go-to working weight.

Take the right stance
Position your feet shoulder-width apart and slightly above the center of the platform, shoulders and back firmly pressed into the back support. Squat slowly, descending as low as you can, then drive your heels into the platform to rise up and stay just a touch shy of locking out your knees at the top to finish the rep.