Want to get fit with the help of a celebrity trainer? Now you can. We teamed up with Harley Pasternak—who trains celebs like Ariana Grande, Rihanna, and Lady Gaga—to learn the best exercises to strengthen and tone the back of your body. 

According to Pasternak, we spend so much of our time working out the anterior parts of our body (think: abs, quads), that the muscles in the posterior chain—like the triceps, glutes, and deltoids—tend to be forgotten. 

The solution? These five simple exercises that work the all-important muscle groups and help to improve your posture too.

One-arm dumbbell row

Start from a lunge position with your left leg forward and your left elbow resting on your knee. Grab a dumbbell with your right hand. Row the dumbbell up along your ribs, squeezing the right shoulderblade. “I always tell people, imagine you’re starting a lawnmower,” Pasternak says. 

Stiff-legged deadlift

The stiff-leg dead lift that works your hamstrings, hard. Hold a dumbbell in each hand, placed in front of your hips. Imagine you’re pushing your hips back on a horizontal track, and then move them forward again. Your weights should go down only as far as your hamstrings you’ll allow without rounding your back. You should feel a stretch in your hamstrings as you extend back. 

RELATED: Try Emily Skye’s Lower Body Workout to Target Your Legs, Core, and Butt

Lying triceps extension

Next, we get at the tough-to-tone backs of the arms with triceps extensions. Lie down on your back with your knees bent, feet flat on the floor. Grab your weights and place them on either side of your head, elbows bent, and then extend your arms straight above your head. Repeat. Pasternak, who’s also a nutritionist and best-selling author, calls this one of the best ways to get cut upper arms fast.

Hip thrust

Lie on your back with your knees bent, feet flat on the floor. Bring your elbows into your sides. Dig your heels into the ground, engage your glutes, and push your hips up. Lower slowly, and repeat. Make this move harder by adding a lying triceps extension. 

Superwoman

Lie on your stomach. Extend your arms out in front of you, or bend your arms and place your hands near your temples. Lift your upper body and lower body simultaneously. Repeat.