Answer to Question 1
The first step in systematic desensitization is to learn how to achieve deep relaxation through training in abbreviated progressive muscle relaxation. The next step is to create an anxiety hierarchy. The hierarchy can be thought of as a fear ladder with the least fearful phobic stimulus residing on the lowest rung of the ladder. Fear can be measured on a 100 point scale in units called Subjective Units of Distress (SUDS). Each rung then consists of images that provoke a gradual increase in SUDS until reaching the top rung that contains the image that provokes the highest SUDS. Generally there are 10 to 20 rungs on the fear ladder. In addition to constructing a fear hierarchy, individuals select one or two relaxing images they can use to calm them when needed while undergoing systematic desensitization.
Answer to Question 2
Generally muscles should not be held for too long in a tense stateno more than 5 to 7 seconds to prevent any muscle cramps. Holding the tension for a count of 5 before releasing the muscle is a good rule of thumb. Avoid overstraining the muscles. For example, muscles should not be quivering when tensed. When doing the exercises, avoid tensing potential trouble spots like your abdomen if you are pregnant or any injured or strained muscles like those in your lower back if you have low back pain.