Yoga, and the benefit of yoga, is generically defined as a Hindu discipline that helps unite the body and mind. Aimed at achieving a state of perfect spiritual insight and tranquility, it is practiced in the West most commonly as physical exercise practiced as part of the discipline.
bikram

The Power of Stretching
Your muscles ache from a good stretch. This is quite normal and is part of the process. Stretching has seemingly been with us and particular with athletes since the beginning of time.