Proper posture is the key to no strain. Sit with your back straight in the chair. The height of your sewing should be where your arms are bent at the elbows and your hands rest on the sewing quilt surface. You should look like this when machine quilting on a domestic machine L with the L also being your arm bent. You are looking down on your sewing not looking into it. DO NOT extend your neck forward, keep it straight and drop your head down. After I learned to sit properly I can sit and sew all day with no back, shoulder or neck pain. It works great for machine quilting. I have more control and it's easier to see what I'm doing.