AREAS OF INTEREST: FLEXIBILITY, STRETCHING, PNF, AI, BALLISTIC, STRETCH REFLEX, GOLGI TENDON ORGAN. by: Tom Seabourne Ph. D After you have warmed your muscles by jumping rope, jogging in place, or jumping jacks it's time to stretch. For safety, never stretch a cold muscle. It should take you no more than ten minutes to finish a full body stretching program. … [Read more...] about STRETCHING LUBRICATES YOUR JOINTS, KEEPS YOU RELAXED, AND IMPROVES YOUR COORDINATION.