If you’ve ever been in the gym and watched someone Instagram themselves on the squat rack, they’re most likely using #legday. And while you might roll your eyes (especially if they’re hogging the rack), this type of training—mega-popular in body-building—has a name: split training.

No, we’re not talking about the work you have to do to achieve a Simone Biles-style split. “Split training is a strength training methodology that harkens back to Arnold Schwarzenegger’s hay day,” says Grayson Wickham, DPT, CSCS, and founder of Movement Vault. “It’s when your workouts throughout the week are broken up by muscle groups or body part.”

The purported benefits of honing in on individual muscle groups include anything from increased muscle mass to amped-up calorie burn. But what’s so special about this type of training? And is it better than full-body training? We asked the experts to find out.

How does split training work?

Split body training looks at your workout from a weeklong or month-long viewpoint. Each day of exercise is usually broken up into a “primary focus” (like legs, back, shoulders, chest) and “secondary focus” (like abs, triceps, and biceps).

“To maximize training, you need to systematically break up what areas of the body you want to focus on each day to avoid over-training or injury,” Wickham says. If you don’t give your muscles enough of a break (about 48 to 72 hours to repair and grow back stronger), you aren’t giving them enough time to properly recover. “Split training—when done right—does just that,” Wickham says.

Should you be doing this?

Asphalt Green master trainer Art Koharian, CSCS, says it’s best for athletes who have time to work out five to six times a week because it takes time to execute and plan. “I wouldn’t recommend it for beginners or even intermediate or recreational exercisers because they will simply not be able to put in the work to reap the benefits of split body training,” Koharian says.

If you categorize yourself as an “avid exerciser,” “athlete,” or “bodybuilder,” this type of training program might be for you. Regardless of whether you’re a gym newbie or a longtime lifter, a certified trainer can help you create a program with your needs and goals in mind.

Uh, so what would that actually look like?

Tone House training manager Zack Daley, CPT, shares his split training schedule with us below:

Day 1: Chest and Triceps Examples:chest press, incline chest press, chest flies, triceps extensions, triceps pull-downs.

Day 2: Back and Biceps Examples: pull-ups, rows, bent-over rows, rear delt flies, biceps curls.

Day 3: Legs and Abs Examples: squats, lunges, deadlifts, hanging leg raises, cable crunches.

Day 4: Shoulders and Triceps Examples: Shoulder press, lateral and front delt raises, skull crushers.

Day 5: Biceps and Triceps Examples: biceps curls, hammer curls, triceps dips, triceps kickbacks.

As you can see, Daley’s program prioritizes upper body, but depending on your goals, yours might prioritize legs. That’s why—beginner or advanced— if you’re going to train this way, your program should be in alignment with your fitness goals, says Katherine (KG) Gundling, CF-L1 trainer at ‪ICE NYC.‬ “Split training requires a lot of smart planning and programming by an expert.”

Can’t we just do it all?

“Full-body training is when you train the whole body—legs, arm, chest, core—at some point during the same workout,” Koharian says. Usually, boot camps and HIIT classes are full-body. If you taste-test all of the gym-machines during your workout, that’s also considered full-body. There is no single, universally agreed upon full-body workout, which is great for people seeking variety and customization in their routines.

Founding Mirror trainer Gerren Liles, CPT, likes to think of full-body training as “functional training.” That’s because most full-body routines incorporate a strength, endurance, mobility, and agility component, which work together to create a well-rounded athlete. “Full-body training is more transferable to real-life experiences than split training for most people,” Liles says.

The catch? If you’re able to actually walk (as opposed to, ya know, crawl) into the gym for a full-body workout seven days a week (or even five or six days), you’re likely doing it wrong.

“Full-body training hits on all the muscles in your body and adequately stresses and works them to promote cardio-gains and muscle growth,” Koharian says. Translation: If you do a full-body workout two days in a row, you’re probably working out the exact same muscle groups as the day before. And the blunt truth is, you’re not recovering properly.

So what’s better? It’s a debate that’s been going on for years.

While there are some people who will defend one side over the other with an almost-feverish devotion, most trainers recognize that both training styles can be part of a well-rounded, healthy workout routine.

That’s why the real question isn’t which is better overall, but which works best for you right now given your time, goals, and current fitness level. The following four guidelines can help you decide which training method is better for you:

If You’re New to Exercising: Full-Body

“Typically a full-body is routine the best way to start to develop overall balance, body awareness, and fitness, while split training is a way to build on that foundation,” Gundling says.

For #Gains: Split

“If your goal is to gain muscle, choose split training. It is an effective way to target and shape muscles to build a specific physique,” Liles says. However, if your goal is simply to improve your overall health markers or you’re just transitioning to strength-training work, full-body train instead.

If You’re Short on Time: Full-Body

If you don’t have a ton of time, full-body wins. “Split training is a great option for anyone who knows they can consistently work out for a decent bit of time five days a week. If you can only work out two or three days a week or are limited by time, full-body is a better use of your time,” says certified professional athlete strength and conditioning coach, Manning Sumner. All you have to do is commit to a quick HIIT workout (like this one), without worrying about reps or rest between sets.

If You’re Injured: Split

Yes, you could work around an injury in a full-body class with the help of an instructor, but it may take a little finagling. If you’re coming back from injury or have what Sumner calls a “lagging body part,” split train. “A split training program can help you train around an injury or train one particularly weak muscle group,” he says.

Gabrielle Kassel is an athleisure-wearing, adaptogen-taking, left-swiping, CrossFitting, New York-based writer with a knack for thinking about wellness as a lifestyle. In her free time, she can be found reading self-help books, bench-pressing, or practicing hygge. Follow her on Instagram.