There are two main causes of back pain when bending over. The first condition is lumbar muscle strain. Because patients with lumbar muscle strain have inflammatory lesions in the lumbar musculature or fascia, they tend to experience increased pain when they are cold and strained. When bending over or bending over for a slightly longer period of time, it leads to continuous fatigue of the muscle tissue. The continuous stimulation of the inflammatory lesion will lead to a more pronounced soreness of the lower back. This is due to the production of metabolic products such as lactic acid after the muscle tissue becomes fatigued. After stimulation of the peripheral nerves, the symptoms of low back pain can occur. The second condition is due to prolonged bed rest after surgery or in patients with fractures or dislocations. After a long period of bed rest, the strength of the lumbar musculature is reduced and the degree is significantly decreased. As a result, when bending, the muscle strength decreases, it is very easy to feel fatigue, so the symptoms of lumbar pain will also occur.