If you cannot perform pull-ups, perform hanging leg raises (or toes-to-bar) on the bar to achieve them.

noli's read

The idea of training while hanging from a bar to progress is very relevant, as active hanging strengthens grip force and shoulder stability, two essential pillars for succeeding at a pull-up. A biomechanics study led by the team of Stuart McGill (2014, EMG muscle activation measurement) confirms that hanging leg raises strongly recruit the latissimus dorsi isometrically to stabilize the upper body. However, presenting the full leg raise as the ideal method for unlocking your first pull-up is somewhat disproportionate. The pull-up primarily requires dynamic (concentric) pulling force from the back and arms, whereas the leg raise mainly engages the anterior chain (abdominals and hip flexors). For a practitioner who does not yet have the strength to perform a pull-up, this hanging exercise often proves too demanding for the grip. Physical preparation guides (expert opinions in calisthenics) instead recommend direct pulling progressions, such as negative pull-ups or horizontal pulls, to build the specific strength required for the movement.

the sources

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