In 2018 an EMG study (1) found that the most activated muscles during a pull-up are in declining order:
- abs (rectus abdominis)
- biceps (biceps brachii)
- lats (latissimus dorsi)
That the abs are heavily involved should be visible from this picture:
Further 3 exercises commonly used to train up to being able to do pull-ups were studied:
- seated lat pull downs
- machine assisted pull-ups
- kneeling lat pull downs
The first two had very little ab activation,
whereas the last has good ab activation.
Band assisted pull-ups are even worse than machine assisted pull-ups since the band will provide the most assistance at the bottom of the movement where one is strongest and least assistance at the top where one is weakest (4).
The conclusion of this is:
a good way to work up to doing pull-ups or chin-ups is to do kneeling lat pull downs:
Since the abs are so important for chin-ups/pull-ups it is a good idea to also strengthen them directly.
Since the lats are a shoulder internal rotator it is important to balance vertical pulling out with rows and training rear delts using facepulls(2).
An example back workout for working toward chin-ups or pull-ups
- Facepulls: 4x12
- Kneeling lat pulldown: 1x12, 1x5, 1x10
- Seated rows: 3x10
- Captain's chair leg raises: 2xAMRAP
Keep 1 or 2 reps in reserve for each set.
Do this workout 2 x a week.
(1) A Comparison of Muscle Activation during the Pull-up and Three Alternative Pulling Exercises
(2) The Posture Cure
(3) Do More Pullups Now
(4) Bands Are For Pushing, Not Pulling