Ergonomics advices

1. Sit up straight at the end of the seat and lean you back against the chair backerest. The best and most natural position for the body is to be standing. When you are sitting down at work, the pressure on inter-vertebral discs is increasing. With a straight position of your abck, pressure will be dispatched between your discs, your ribcage will straighten, and thus increase your vital capacity and make you breathe easier as well as improve your heart functioning.

2. Adjust the height of the backerest, which has te be against the lumbar region of your back. High back stuffing provides a support between the shoulder blades, which makes your ribcage straight and thus prevents from gaving round shoulders. Moreover it makes blood circultation easier.

3. Then adjust the seat height so that your feet should rest flat on the floor or the footrest in order to prevent pressure under your thighs.
Whatever the seat angle you have chosen, the angle of your thigh with your leg must keep close to 90°.

4. Adjust the armrest height.
It's recommended to create a working environment, which will allow arms to be as close to your body as possible. The armrests will be supporting your forearms and thus relieve the pressure on your vertebral discs, reducing tensions on your shoulder blades and your neck. Either standard or adjustable, armrests have to be suited to each person and each specific task. They should be slid under the desk. 

5. Adjust the backerest tilting system according to your weight.
Try not to be sitting down too long and stand up from time to time. Use the various functions of your chair, alternante between forward and backward sitting positions so that your back can relax. 

Be dynamic in your working positions !
Chairs have to be the mainspring of your workstation and should be tailored as required.