One of the most important tenets in program design for fastest wins is:
"A chain is only as strong as its weakest link. Strengthen the weakest link and the whole chain will become stronger..."
Especially for women, the weakest link and thus the limiting factor in pull-ups is usually the lower quarter of the movement. Initiating the pull-up from a fully extended elbow. In this case, the muscular limiting factor is elbow flexor strength.
There are 4 muscles that flex the elbow - biceps, brachialis, brachioradialis and pronator teres.
Statistically, the brachioradialis and pronator teres are the two weakest and most limiting elbow flexors.
Is your brachioradialis and pronator teres too weak? The simplest indicator is the ratio of your supinated, shoulder-width pull-up to reverse EZ dumbbell curls with a shoulder-width grip. The optimal ratio is 1:0.37. This means that if you want to do a pull-up with a body weight of 60 kg, you have to do reverse EZ dumbbell bar curls with a shoulder-width grip with 22 kg. If you can't do as much, your elbow flexors will be a limiting factor in pull-ups. The same relationship applies if you can already do several pull-ups or are already using additional weight. Calculate and optimize the ratio of supinated, shoulder-width pull-ups to reverse EZ dumbbell curls with a shoulder-width grip for more pull-up power...
Here is a sample progression for curls over 12 weeks - to strengthen the elbow flexors:
Phase 1 - 6 workouts/3 weeks
EZ dumbbell curls, standing, shoulder-width grip, 4×6-8, 4010, 120s
Phase 2 - 6 workouts/3 weeks
45° KH Incline Hammer Curls, 4×4-6, 4010, 150s
Phase 3 - 6 workouts/3 weeks
65° KH incline curls, supine grip, 4×5-7, 4010, 120s
Phase 4 - 6 workouts/3 weeks
Reverse EZ dumbbell curls, shoulder-width grip, 5×4-6, 40×0, 150s
Each rep starts and ends with your elbows fully extended.
It's critical to increase the weight and/or reps of each workout. Weight progression is critical to increasing elbow flexor strength.
Do each exercise twice a week for 3 weeks as the first exercise in your upper body workout, then move on to the next phase.
For these 4 phases, you do eccentric pull-ups as the second exercise of each workout – as described here . After the 4 phases you then switch to pull-ups as the first exercise in your upper body training.
Good luck with the pull-ups!
Image: IFBB Bikini Pro Kate Abate does reverse EZ dumbbell curls with a shoulder-width grip (left) and 45° KH incline hammer curls (right) at the YPSI Hypertrophy & Fatloss Seminar at WorkoutRD in Santo Domingo, DR