Do Videos That Aim to Optimize Expectations Alter the Effectivess of PMR?

"All groups undergo a PMR session, but they differ regarding the treatment before the PMR session. Two groups watch a video before undergoing PMR, the control group reads a text before undergoing PMR.~Progressive muscle relaxation (PMR) is a technique for learning to monitor and control the state of muscular tension. It was developed by American physician Edmund Jacobson in the early 1920s.~The technique involves learning to monitor tension in each specific muscle group in the body by deliberately inducing tension in each group. This tension is then released, with attention paid to the contrast between tension and relaxation."