I've been doing some research on stretching for musicians. Most of the tension we have comes from our hands, neck, back, and shoulders. Many articles i've read show that stretching before practicing can reduce injury, and reduce the tension you experience while practicing. Here is a link I found for some yoga stretches for musicians. Doing simple stretches such as shoulder shrugs, and squeezing your shoulder blades can help relax you before your practice. Since many musicians experience strains such as Thoracic Outlet Syndrome, Bursitis, and Tendonitis.. stretching is vital for us.
Another interesting article I found.