What are the reasons why the waist is easily sprained? What movements can easily cause a sprained waist?

In life, older people often suffer from low back pain due to an unintentional movement (such as moving flowers, bending over to pick up something, etc.). At this time, the patient may experience low back pain and a strong sense of tightness. So why is the waist so easy to sprain?

Muscle injury generally refers to muscle strain. Why do muscles get strained?

As the name suggests, a strain is an injury to a muscle due to excessive stretching. Muscle contraction is divided into eccentric contraction, concentric contraction and isometric contraction. Muscle strain is most closely related to the eccentric contraction of the muscle, because the eccentric contraction is the process of muscle lengthening. If the muscle is suddenly subjected to a large force and its eccentric contraction ability is poor, the muscle will be strained.

Why is the lumbar muscle not easily strained?

The lumbar muscles are located behind the spine. Their position and attachment points determine the main function of the lumbar muscles: when both sides of the lumbar muscles contract simultaneously, the trunk is extended posteriorly, while when one side of the lumbar muscle contracts, the trunk is flexed laterally.

People usually do the following actions:

1. Trunk extension movements: such as stretching, swinging the racket to smash the ball when playing badminton.

The lumbar muscles are in a state of concentric contraction; at this time, the lumbar muscles are relatively stable and not easily injured. (At this time, if the contraction force of the psoas muscle is too strong, or the morphology and function of the lumbar intervertebral disc and deep intervertebral soft tissue are abnormal, the spinal nerve roots may be compressed due to excessive narrowing of the intervertebral foramen, causing lumbar pain symptoms.)

2. The trunk is fixed vertically:

The lumbar muscles are in an isometric contraction state; at this time, the trunk itself is relatively stable and the lumbar muscles are not easily injured; but long-term weight-bearing (isometric contraction) may also cause muscle soreness and discomfort.

3. Trunk flexion (bending):

The lumbar muscles are in a state of eccentric contraction; at this time, if there is no obvious weight bearing or the movement is not rapid, the lumbar muscle load is not large and the lumbar muscle is not easily injured; normal people will only have a real "lumbar muscle strain" when the lumbar muscles exceed the load during eccentric contraction when they bear a considerable weight for a long time or the trunk is bent forward rapidly.

However, such actions are not common in daily life. Carrying heavy objects for a long time, bending down suddenly to pick up something, or bending down to pick up something while carrying heavy objects and certain special movements may meet this requirement, but the rest are rare.

4. Trunk rotation (sideways)

When the trunk rotates, the unilateral psoas muscle will generally be in a state of eccentric contraction. This kind of rotation can easily cause psoas muscle strain, especially in the elderly in the swimming pool, where the temperature difference makes the muscles more susceptible to strain.

5. Posture Transition

During the transition from squatting and sitting to standing up, and during the upper limb raising process, the waist muscles are in a state of isometric contraction or concentric contraction. As we all know, muscles in concentric contraction or isometric contraction are not easily injured.

So, if it is not "lumbar muscle injury", what is the reason for the patient to experience symptoms of low back pain and limited movement?

In these injury movements, sometimes it is the eccentric contraction of the psoas muscles, but more often the "eccentrically contracted" muscle group is the abdominal muscles.

The stretching and spraining of the abdominal muscles during the eccentric contraction process is the "culprit" that directly or indirectly causes low back pain and limited mobility in patients. It is acute abdominal muscle stretching and spraining.