Why does my back hurt when I bend down?

Well, when we bend down, it can put a lot of strain on the discs in between the vertebrae in our low back. That can be one source of discomfort in the low back. It can also mean that there are several tight muscles in the back or front of the thigh or around the low back that are pulling on the pelvis and low back indirectly and as we go to stretch those, they put more tension into the back. There are also some muscles on the front and side of the spine that can be tight and put stress on the low back as well too. So when you are talking about low back pain it can be caused from several different things, but that bending forward, especially if the knees are straight, can put a lot of strain on the low back.

So if you do have bend forward, I would strongly recommend squatting down, keeping your shoulders and hips square, bending from the legs, moving from the hips as opposed to flexing forward at the spine, that will help keep pressure off your low back. Also, stretching, meditation and core stability exercises will help your low back get healthier.

When you bend forward at your waist, and keep your knees straight, you put tremendous stress on the muscles, nerves, joints, and ligaments in your low back. To decrease the pain in your low back when you bend forward, pull your belly button in towards your spine (this activates the muscles the help support your low back). Also, make sure to bend your knees and keep your chest up as you are bending and lifting. This significantly enhances the stability of your entire low back and pelvis area. Furthermore, prevent potential back pain by conditioning your core muscles to handle increased stress during daily activities. Stretch and strengthen the muscles surrounding your hips and low back for optimal low back health: 

1. Stretch. Stretch your hip flexors and hamstrings. Perform static stretching, holding a stretch for 30 seconds each, on the muscles in front of your hips (your hip flexors) and the muscles in back of your thigh. Both of these areas can lead to misalignment of the hips and spine, which could eventually lead to back pain.
2. Strengthen. Strengthen your abdominals, low back, and hip muscles. Exercises like the all 4s arm/leg raise, floor bridge, planks and squats help to condition the muscles to increase their endurance and strength—two things you will need to keep your back healthy.