Yes, vigorous stretching and other physical activity in someone not accustomed to it can cause muscles to go into spasm and result in a "pinched nerve" or nerve entrapment. The most common nerve involved in headaches is the occipital nerve with pain starting in the back of the head and often radiating forward. Pain medications, muscle relaxants, heat, acupuncture, and massage can help, but when the pain persist an occipital nerve block can be very effective. The best way to prevent this is to stay in good shape - doing aerobic exercise, 20-30 minutes 4-5 times a week and isometric neck exercise to strengthen neck muscles. In unusually prolonged cases that do not respond to treatment, Botox injections can be very effective. For more info see
www.NYHeadache.com