Today I'll explain a very useful preliminary pull up exercise to you - The Jackknife Pulls. If you wanna get serious about performing full pull ups one day and haven't got enough power to do at least 5 slow reps of full pull ups yet, you should invest some time in this exercise. It has a lot of similarities with regular pull ups, even though jackknife pulls are way easier! This exercise will (especially if you perform it with the 2-1-2 cadence) help you to develop enough strength in your upper back and biceps to enable you to go further in your pull up progression process. The movement is quite similar with normal pull ups, but it's just half as hard, because some of the power to pull yourself up comes from the support of your legs/heels. This fact causes another big advantage of this exercise, in particular when you care about your joints and tendons at your elbows and shoulders. While they have to carry all of your bodyweight during regular pull ups, the stress they have to endure is less when performing jackknife pulls. They get the needed time to adapt and strengthen, so that they eventually are able to withstand the upcoming stress of full pull ups (after you are able to perform the target reps with the mentioned movement speed). Just give this exercise a go before you do full pull ups (btw. just because you are strong enough to do full pull ups doesn't necessarily mean that your whole body is capable of resist the load!).
Let's start with the the how-to-perform explanation:
First off, you have to find a horizontal bar that allows you to sit below it in a jackknife position (L-position) when you hold on it (use an overhand grip) with your arms shoulder-width apart and almost straight (your butt should be slightly above the ground). You can use a Smith machine (like I did in the video) for example or you use a normal high bar with an object situated in front of it, that allows you to place your heels on it, so that you end up in the jackknife position by hanging on the bar with your arms almost straight and your legs fully straigthened out. Now pull yourself up slowly until your chin passes the bar (2 sec). Support this movement part by pushing down with the power of your legs (through your heels). Hold the finish position for a second and lower yourself down slowly and controlled until you reach the start position again (2 sec). Repeat the movement without a rest. If you can't manage to meet the target instantly (which is probably the case), do as much reps as possible each set, until you can do the requested amount. Be careful if you use a high bar and an object for performing the exercise! In this case always stop the exercise and get down safely before muscle failure (you should avoid to fall down with your butt first).
Remember to keep your shoulders tight all the time (as mentioned in the post about the vertical pulls)!
Target: 3 sets of 20 reps
Let's do it to come closer to the full pull ups!