If you look at the age-old techniques of building strength in the upper body, parallel bar dips will be one of them. Parallel bar dips are one of the most effective exercises to challenge the strength of your upper body especially the extensor group and pushing group that includes shoulders and triceps. Your core does its job of stabilizing your body and thus working effectively in further improving its strength.
One of the main reason why this works well is the fact that it is a closed kinetic chain exercise. A closed kinetic chain exercise is where you do not take help of the kinetic force as the legs are in the air while you perform this movement. As a result, dips work simultaneously both while lowering as well as lifting the body. If you are s strength training junkie and if you are performing this exercise to failure, then maybe your last reps could be with the use of kinetic energy as a cheating form.
This exercise also builds your lockout strength. Lockout strength is used in every pushing movement like the chest presses, shoulder presses etc. This exercise is no different. The range is not complete until you do a complete lockout which helps to improve your lockout strength overall. As a part of the progressive overload, this exercise helps you by giving the ability to add more weight as you progress with the poundage.