In general, many underestimate the effects of breathing during a weight training exercise. Yet breathing plays a very important role in performing exercises. The better you will breathe during your exercises, the better your muscles will work!
The two phases of the movement:
Contraction of the muscle
This is the phase where the muscle is solicited. For example, if you do a bench press, you start the movement with the muscles relaxed and the contraction will be to lift the bar with the weights.
This is the phase where the muscle relaxes. In the example of the bench press, the release phase corresponds to the moment when you lower the bar, in a controlled way towards the initial position.
We find these two phases in all bodybuilding movements, whether for the shoulders, pecs, legs, etc …
How should you breathe?
Proper breathing is simply breathing (exhaling) when you are in the muscle contraction phase and taking your breath (inhaling) during the muscle relaxation phase.
So it is relatively simple: if we take the example of the bench press: you will inspire at rest, start the exercise by blowing (lifting the bar), inspiring down the bar, exhale back and so on.
You will find the same thing for each of your exercises: blow during the contraction of the muscle, inhale during the relaxation of the muscle.
Still in our bench press exercise, at the end of lifting the barbell, contract the working muscles well enough to empty your lungs and then start the descent by blowing. Your muscles will work even better!