I blame bodybuilders for the creation and perpetuation of body part splits. It works for them because they typically have hours a day to train and they train almost every day of the week. You've likely seen these types of workouts before with terms that refer to muscles/parts of the body: back, bis, chest, tris, shoulders, legs, etc.
There is nothing inherently wrong with structuring your workouts this way, but it’s inefficient for folks that don't want to spend all day in the gym and don't have the schedule or desire to work out every day.
There is a better way for us muggles.
The Movements
Movements can be broken down into four categories:
Upper Push
Upper Pull
Lower Push (Squat)
Lower Pull (Hinge)
Upper Push
These are exercises where you're pushing a load away from you or pushing yourself away from a surface using your upper body. Bench press, overhead press (just called a "press"), chest press (machine), shoulder press (machine), and push-ups are all examples of upper body pushes. These primarily target the chest, triceps, and front/middle of the shoulders to some degree.
Upper Pull
When you pull a load to you or pull yourself toward something using your upper body, you're performing an upper pull. This category includes pull-ups, chin-ups, lat pulldowns, and row variations. These exercises primarily target the upper back, back of the shoulders, lats, and biceps.
As you can see, with these two complementary categories, you've hit every major muscle group in the upper body. There's no need to worry about muscle groups when you are able to simply combine pushes and pulls to create your workouts. On to the lower body exercises.
Lower Pushes
Lower pushes, or squat-ty movements, involve you pushing a load away from you or pushing yourself away from a surface with your lower body. Examples include squats and squat variations, leg presses, lunges, step-ups, and split-squats. The primary muscle group in this category is the quads, but you will frequently use the glutes and hamstrings as well.
Lower Pulls
To fulfill the lower pull or hinge category, you need to incorporate deadlifts, RDLs, hip thrusts/bridges, or machine versions of any of these movements into your workouts. The goal is to move the resistance by shortening the glutes and extending (straightening) the hips. Unsurprisingly, the glutes are the primary muscle group for these exercises, but you'll also target the hamstrings and back for many of them.
The line between lower pushes and pulls is more blurry than their upper body counterparts, but you can still easily cover your bases by combining exercises from each category.
Why Are The Movements Above Superior To Focusing On Body Parts?
Movements always target multiple muscle groups
Because each movement category involves multiple muscle groups, you can target more muscle with less exercises than if you tried to use exercises that only target one muscle group at a time. I'm not saying body part splits can't also contain multi-joint movements, but they leave open the possibility of using isolation exercises that only target a single muscle or muscle group. Movement-based programs do not.
It's easier to keep track of four categories than one for each muscle group
You could theoretically include all four categories in each workout day and automatically have a very balanced program. If you would rather split them up differently, simply having some sort of representation from each category throughout the week would ensure you're not leaving anything out. It's much harder to do that when you're keeping track of muscle groups; there are a lot more of them and the list will include lots of okay, but ultimately unnecessary isolation exercises.
Movements are inherently complimentary
Pushes and pulls are complimentary by default, so you don't have to worry about much overlap. Due to the minimal muscular interference, you can pair them together in supersets to make your workouts even more efficient.
Movement-Based Workout Examples
Here is an example of two 4-exercise workouts you could use. This is a very bare bones workout, but it would work well for someone looking to build strength and muscle in a simple, yet balanced way. The more time and days you have to workout the more you can add overall exercise variety, separate each category into subcategories, and add isolation exercises like bicep curls, lateral raises, calf raises, tricep extensions, etc.
Here are some important lessons for putting workouts together:
Don't pair up exercises that use the same piece of equipment. You don't ever want to be the person taking up all the barbells, dumbbells, or whatever. The only exception might be machines, because you're not moving them and they're easy to adjust.
Use as much overlapping equipment as possible. I like pairing back squats and chin/pull-ups because you can typically do them both in a rack without extra equipment. I've also paired hip thrust and dumbbell bench press because both exercises can utilize the bench.
Pair exercises that don't have the same or similar limitations. For instance, lower and upper pulling exercises (like the deadlift and chin-ups) are both grip-intensive, so they might not work well together.
You could also fix this problem by getting straps or, my favorite, Cobra Grips.
Because these types of workouts are short, you can do them one at a time if the logistics just don't work when paired.
Hopefully you learned something. Please feel free to drop a comment if you have any questions about how to put a workout together or other general fitness/nutrition questions.
Thanks for reading.