When it comes to choosing a split, a lot of what you decide comes from personal preference or what proves to be the most mentally motivating, and not much else. Applying some science to your split can go a long way towards continued gains and injury prevention.

Here's a basic guide on how to structure your workout week and what exercises you should include.

Day 1: Back

Starting your workout week with a back workout makes the most sense for a few reasons. First, most people's strongest, heaviest, lift is their deadlift or deadlift pattern. Programming this body part first in the week will likely coincide with a time the body is the most rested and recovered, generally after a weekend of lower stress. If there's any time to crush a heavy pull, it'll be when you're physiologically at your best.

Second, we need to think of what we're preparing ourselves for: the rest of the week. If heavy lifting is on the upcoming week's menu, working back first creates a good opportunity to load up on decompression exercises that don't put excessive stress forces on the spine right from the get-go. With the exception of deadlifts, there are plenty of exercises that can do just that.

Here are the best back movements for hypertrophy (size) that you can choose from to build your workout. Decompression exercises are marked with an asterisk:

  • Deadlift
  • Pull-Up *
  • Pulldown * (Paused rep pulldown shown below)
  • Seated Row
  • Bent-Over Row
  • Single-Arm Dumbbell Row
  • J Rope Pull *
  • Straight-Arm Pulldown *

Day 2: Chest

Most workouts will cause muscle soreness that can limit the flexibility and range of motion of the muscles in question. We can use this to our advantage by programming chest work after a back day.

When the scapular muscles are pulled shorter and tighter due to delayed onset muscle soreness (DOMS) from our back workout, it actually can help to stabilize the shoulder joint by limiting the available range of motion for the scapulae to travel through (at least without discomfort). That means retracting the shoulder blades will be easier to do, since putting them into a stretched position will feel funky.

The bench press, chest flye, and incline press will hence feel much more comfortable and stable since all of the upper back muscles are doing exactly what's being asked of them by default – staying tight. You'll have no problem hitting your chest without enduring shoulder stress.

It's also important to hit the chest from both pressing and flying patterns, and with the sternal and clavicular pecs in focus. Start with pressing patterns to create microtrauma and then using flye patterns later to build on this trauma. Key exercises include:

  • Low-Incline Dumbbell Bench Press
  • Barbell Flat Bench
  • Bodyweight/Weighted Dip
  • Incline Cable Pec Flye
  • Standing Cable Pec Flye
  • Dumbbell Pec Flye

Day 3: Legs

Legs go third in the split to give the upper body a break. Leg workouts are the most physically demanding of the entire week and they deserve a scheduled rest day immediately before or immediately following the workout.

Depending on how sore and restricted your chest is the day after a workout, it may also be a bit difficult getting the hands into the proper position for back squats, so taking the extra day off right after chest day may come in handy.

Pre-exhaust techniques usually do a world of good when it comes to optimal leg performance, especially if you've struggled to get your joints feeling A-OK during days where you're supposed to squat big.

Hitting the posterior chain first (specifically, the hamstrings) can do a whole lot to stabilize the knee joint from the opposing side while putting the quads through a dynamic stretch. This requires low-volume, open-chain isolation exercises. Effective exercises include the seated or prone hamstring curl machine and the 2-and-1 Swiss ball curl (see video).

Outside of those "prep" exercises, go-to leg exercises for guaranteed hypertrophy include:

  • Front or Back Squat
  • Leg Press
  • Walking Lunge
  • Heels-Elevated Goblet Squat
  • Glute Hamstring Raise
  • Romanian Deadlift
  • Prone Hamstring Curl

Day 4: Shoulders

Since your upper body is now rested, the shoulders should be ready to do upper body pressing exercises that are similar in nature to those in your chest workout.

It's also smart to program shoulders before training arms and not after.

Similar to leg day, there are important things to consider when training shoulders for size, especially when you're someone with a history of shoulder issues. Some programs don't consider this and avoid preparatory exercises that can help stabilize the shoulder joint before pressing.

Doing the following exercises for low volume can be a saving grace to cranky shoulders as they'll set the tone and improve the performance of your shoulder work:

  • Inverted Row
  • Reverse-Grip Pulldown

One more thing: The shoulders and traps respond well to heavy loading, which speaks to the fast twitch characteristics of the upper traps. Heavy triples should be a staple for barbell moves like the following:

  • Barbell Snatch-Grip High Pull
  • Barbell Strict Press
  • Barbell Behind the Neck Snatch-Grip Push Press

When doing volume work, changing the joint angle and using dumbbells and cables is especially effective. It can be a fantastic follow-up to strict pressing and other heavy barbell work.

  • Neutral-Grip Seated Dumbbell Press (with fat grips and a slow tempo)

Finishing off the shoulder workout with lateral raises and flye patterns is a smart way to round things out. You enter a different force curve and force plane and target the much neglected rear deltoids where applicable:

  • Bent-Over Reverse Flye
  • 2-Rope Face Pull
  • Cable Lateral Raise

Day 5: Arms

It's important to train arms after shoulders in your workout week. Otherwise, you're fatiguing them before what's normally the heavier of the two workouts, but even more important, you're risking injury on a scientific level.

Filling the biceps with blood (as happens after an arm workout) can lower the amount of subacromial space in the shoulder capsule, especially if you have high muscle bellies and shorter tendon attachments, or just have a propensity towards funky shoulders that are often impinged. So it's a much smarter move to hit the arms on their own, after shoulders.

As far as size gains are concerned, shoot for volume for basically all arm exercises. Here are some of the most effective:

  • Straight-Bar Biceps Curl
  • Incline Dumbbell Hammer Curl
  • Bodyweight/Weighted Dip
  • French Press
  • Pullover-Skull Crusher
  • Chin-Up

Related:  6 Steps to Building the Perfect Workout

Related:  How to Build Your Own Training Program