Breathing is essential to singing, because singers must inhale a sufficient amount of air deep into their bellies and at the appropriate time, powerfully strike the correct notes. Proper singing posture enables singers to effectively breath from their bellies between phrases and melodies. However, poor singing posture -- in which the body is slouched over -- can tighten the stomach and cramp the lungs so that the body cannot smoothly inhale and exhale breaths of air. This restricts the airflow and inhibits a person's ability to use the diaphragm to sing.
For singers to hit the correct notes and strike the right melodies, they must stand with good posture so the body is straight, the limbs are comfortable and the lungs and diaphragm are free to stretch and breath. When the diaphragm is tightened by poor posture, the voice might miss notes or hit the wrong notes during melodies. Inadequate postures can also impair a singer's ability to strike very high notes that are difficult to reach.
The strength and power of a voice depend largely on posture. Tilting the body back and forth, positioning it at an awkward angle or slouching the back can all muffle resonance. In turn, even when a singer using poor posture hits the correct notes, the notes and melodies might have a relatively weak sound, soft volume and low resonance. Furthermore, bad posture can inhibit a singer's ability to hold notes for long periods of time.
Bad posture can cause excessive muscle strain, back pain, spine stress and joint and bone aches. According to Singing Like a Pro, good singing posture can keep your joints and bones lined up properly.