All is in vibration. From the tiniest atom to the greatest sun, everything is in a state of vibration. A single atom deprived of vibration would wreck the universe. The atoms of the body are in constant vibration.
In all vibrations is to be found a certain rhythm. Rhythm pervades the whole universe. The swing of the planets around the sun, the rise and fall of the sea, the beating of the heart, the ebb and flow of the tide, all follow rhythmic laws.
Our bodies are as much subject to rhythmic laws as is the planet in its revolution around the sun. By falling in with the rhythm of the body the Yogi manages to absorb a greater amount of prana which he learns to use at will.
You've heard how a note of a singer can crack a glass. When an army is marching across a bridge they're ordered to break step as the rhythm could bring down the bridge. These manifestations of the effect of rhythmic vibrations will give you an idea of the effect on the body of rhythmic breathing. The whole system catches the vibration and becomes in harmony with the will which causes the rhythmic motion of the lungs.
So lets tune into these rhythms within us and in the cosmos around us, and experience the harmony of rhythmic vibrations in our lives.