What Exactly Is the Posterior Chain and Why Do Trainers Keep Talking About It?

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You may have heard of a little something called the "posterior chain." It's one of those phrases trainers love to toss around—along with "engage your core" and "just 10 more seconds." But what exactly is the posterior chain and why do trainers and coaches keep waxing poetic about it like it's the best thing since coconut oil or black leggings?

We asked experts for the full rundown on the posterior chain. Here, they share what it is, why it's so important, and what you can do to strengthen your posterior chain (because, after this, you'll definitely want to).

What Is the Posterior Chain?

"The posterior chain refers to all the muscles on the backside of the body from the back of your head all the way down to your heels," says certified strength and conditioning coach Alena Luciani, M.S., C.S.C.S., founder of Training2XL. "That includes your hamstrings, glutes, calves, lats, rotator cuff muscles, and erector spinae muscles."

The posterior chain is a total powerhouse: "It includes some of the biggest and strongest muscles in your entire body" says Karena Dawn, certified personal trainer, nutrition coach, and cofounder of Tone It Up. The muscles in the posterior chain play a huge role in everyday activities, such as picking something up off the ground, sitting down and standing back up, or jumping.

Perhaps most importantly, "a strong posterior chain helps reduce your chance of injury and protect your knees and back," says Katrina Scott, certified personal trainer, nutrition coach, and the other cofounder of Tone It Up.

Don't get us wrong: It's important to have a strong anterior chain (all the muscles on the front side of the body—your chest, core, quads, etc.) too. However, "today's lifestyle of sitting lend itself towards an anterior chain-dominant body," explains celebrity trainer and nutritionist Harley Pasternak. "Most popular forms of exercise today like running, yoga, boxing, and walking forward, continue to strengthen the anterior muscles." (P.S. Harley is one of the super-knowledgeable trainers you should definitely follow on Instagram.)

The result? A muscular imbalance between your anterior and posterior chains. What that means: Risk of injury and bad posture, to name a few. (No, thanks.) That's why it's about time that we appreciate what a strong posterior chain can do to keep us strong, healthy, and injury-free in both sports and life.

Why a Strong Posterior Chain Is So Important

1. Improve posture.
A weak posterior chain can lead to slouching. "Sitting all the time can lead to a tight chest, and without strong back muscles to pull back your shoulder blades and keep you upright, you end up looking permanently hunched over," says Luciani. (Related: 7 Dumbbell Strength Training Moves That Fix Your Muscular Imbalances)

Good news: Strengthening your back can help improve your slouch and reduce the symptoms associated with text neck. (No equipment handy? Try this weight-free posture workout instead.)

2. Reduce injury risk.
"When there's an imbalance between the quad and hamstring strength and size, the knee becomes unstable, so you become susceptible to lower-body injuries like ACL tears," says Luciani. Women who participate in jumping and pivoting sports (soccer, rugby, gymnastics, etc.) are four to six times more likely to tear their ACLs than men in the same sports (for a few different reasons), so it's important to make sure that's *not* the case.

Good news: "Strengthening your posterior chain strength to match that of your anterior chain can help reduce risk of ACL tears and other lower-body injuries because it stabilizes the knee," she says. (If you already have bad knees, try these glute exercises.)

3. Run faster.
Stronger hamstrings and glutes equal more powerful legs which equals faster runs. What's more, "if you're a runner, you want to bulletproof your posterior chain to keep your ankle, knee, and hip joints healthy and ward off injury," says Luciani. (That's one of the reasons doing CrossFit can make you a faster runner).

4. Lift heavier.
Whether you're an Olympic weightlifter or a CrossFitter, or just love playing with barbells, having a strong posterior can help improve all your lifts. "In CrossFit and Olympic weightlifting, you're doing movements like the snatch and the clean, which require a lot of power. Strengthening your hamstrings will help you become more explosive in those movements," explains Luciani. (BTW, here's what happens when women lift heavy weights.)

5. Rev your metabolism.
In general, building muscle can help rev up your metabolism. Why? Your muscle mass largely determines your resting metabolic rate—which is how many calories you burn by just existing. (Here's all the #science of why muscle helps you burn fat and calories.) Because the posterior chain comprises such large muscle groups (like the glutes and hamstrings), it's prime real estate for building muscle, says Wilson.

Should You Strengthen Your Posterior Chain?

How do you know if you have a weak posterior chain? TBH, if you're reading this, chances are you could stand to strengthen your posterior chain. But here's a quick test: If you have a weak posterior chain, you can actually see it by looking at your side profile in the mirror, says Luciani. Take inventory of your posture real quick: Are you rounded forward? Is your butt flat? Do your quads pop out from your leg, while your hamstrings lie flat? If yes, it's time to make some PC gains.

Because the posterior chain is made up of so many muscle groups, adding a "posterior chain day" into your workout routine isn't going to cut it. Rather, smart training will sprinkle in exercises that work on different parts of the posterior chain throughout the week. (Here's how to plan a perfectly balanced week of workouts.)

The Best Posterior Chain Exercises

Back squats, deadlifts, lunges, kettlebell swings, glute bridges, calf raises, bent over rows, and pull-ups are your BFFs, says certified personal trainer Alonzo Wilson, founder of Tone House, a group training studio in New York City.

But before you start adding these movements into your routine, quick PSA: Form matters. For instance, deadlifting improperly can have the exact opposite effect from what you're going for (injury.) So before you load up the barbell, learn how to do a conventional dumbbell deadlift, then try these three deadlift varieties. (Related: 3 Most Common Deadlift Mistakes You're Probably Making) Same goes with back squatting and kettlebell swings. Use these tips to learn how to kettlebell swing, and follow these instructions to learn how to back squat safely.

And don't forget your lats! Try this beginner lat workout, these six back-building moves, or improve your pulling strength by trying these pull-up progressions. (Related: 6 Reasons Why You've Never Done A Pull-Up)

It might be tempting to flex your biceps or count your abs in the gym mirror, but the next time you're checking out your reflection, turn around and look back at it. Then, go forth and get after that posterior chain pump—you won't regret it.

"A lot of people in the gym neglect working their posterior chain altogether. But once they do, they find out how much it helps them with other activities that they enjoy in life and sports," says Dawn.