One of my favorite exercises is the humble pull-up! Not only is it great for working your back muscles, it is a complex movement that also hits the core, arms, and shoulders. Many people think that they are doing it correctly, but are lacking on technique which prevents them from getting the most out of each rep.
How to do it correctly:
Start by hanging on the bar with an overhand grip shoulder-width to slightly more than shoulder-width apart. This is the starting position referred to as the passive hang. The first movement should be to engage the middle back muscles. To do this retract your shoulder blades. This position is referred to as the active hang. It should feel like you are trying to do a pull-up without bending your arms. From there, keep your elbows tucked (close to your body) and aim to get the bar to your upper chest. Finally, slowly lower yourself down, minding not to drop into your joints. Return to the active hang position first before relaxing to the passive hang position.
What not to do:
Do not use accessory muscles or momentum to get yourself up to the bar. This is bad technique and you will not target your back muscles effectively. Similarly, make sure you have a full range of motion and are not simply only focusing on the top-half or bottom-half of each rep. Start all the way at the bottom and move all the way to the top. Finally, make sure you are pulling evenly with each arm. Do not overcompensate with one half of your body. This can lead to injuries and muscle imbalances.
How to do it really well, the fine points:
Leg placement is key. Avoid having your legs too far back. It is best to keep your knees in front of your body, whether you have bent knees or straight legs. This is to avoid posterior pelvic tilt which can lead to lower back issues. Tighten your core. By tightening your core you avoid swaying and help focus the exercise where it needs to be, on your back. Finally, at the top of the pull-up try to puff your chest out. This helps prevent rounded shoulders (which can lead to injury) and helps tighten the back muscles further.
Pull-ups are a great complex exercise to help tone and build muscles in the back, core, and arms. I hope you found this short article helpful!