THE MOVE: DOWNWARD DOG
As you bend into this pose, your arm and shoulder muscles contract to support the upper body while your quads kick in and your hamstrings lengthen.

If your hammies start screaming when you press your heels into the floor, you can thank your proprioceptors. These cells monitor muscle length and tension to prevent injury. In this move, the proprioceptors in your tendons go on high alert and try to stop the muscle from lengthening.

As you inhale, your nervous system sends the blood that's rushed to your head back to the heart. Exhaling activates the relaxation portion of your nervous system. Ah, sweet bliss.

IMPROVE LUNG FUNCTION
Researchers at Thailand's Khon Kaen University suggest just 18 short yoga sessions can provide significant improvement to respiratory function by increasing chest wall expansion and "forced expiratory lung volumes".