The catch phase
At the start of a rowing stroke, the hands are wide apart. The seat is moved all the way forward towards your heels. The upper body leans a bit forward, and your back is straight. Everything is prepared to start working. The legs start to apply force, and instead of pulling backwards with the hands, they rather go inwards, as it is the case in the boat. This means more mobility and strenght for your shoulders.
The first drive phase
With the first push of the legs, the force transfers through almost every muscle of your body to the hands, which actually never pull straight, but in semicircles.
The middle drive phase
The legs keep on pushing, and the hands are coming more and more together. The upper body is still in a wait, hold and transfer force position.
The final drive phase
With the final drive of the legs, the upper body is pivoting backwards to add extra momentum to the increasingly quick moving boat. The hands are now pulling crossed over, where the left hand is moving above the right hand.
The finish phase
In the last part of the drive, the arms are now working together with the upper body (and sometimes also with the last centimeters of the leg drive) to continue accelerating the boat. During this phase, the arms are pulling outwards, which results in increased mobility and strength of the shoulders.