When your lower back is under strain, doing this exercise allows you to safely work on your back. It is especially suitable for the last back exercise. By using light weights and focusing on maximum contraction, you can engage the middle and lower trapezius muscles. The key point is to lift your upper body when you lift. (That doesn't mean you should lift it all the way to your chest.) Your lower body should not be completely supported. If you lift your upper body excessively, only the erector spinae will be stimulated. Keep your head at a horizontal level with the ground, and do not lift your head when lifting your upper body.