Ideally, when the hip joint begins to bend, the lumbar spine also begins to bend slightly forward. However, there are many normal changes in this exercise pattern, especially those related to gender: men tend to bend more lumbar vertebrae, while women tend to bend more hips (mainly due to the different lumbar pelvic angles between men and women). Even so, normal waist movement should not account for more than 50% of the total bending range).
Next, in order to bend the body forward further, the lumbar spine will continue to reduce the curvature of the lordosis until it is flat. After this waist movement begins, the hip joint will continue to bend until the body reaches the limit of flexion.
Ideally, the body arrangement at this stage should keep the body balanced on the feet, and the knees passively extend backward, while the ankles, knees and hips should not move backward too much, and the hips should bend about 70 ~ 80 degrees. The lumbar spine is flat, while the thoracic spine will form an extended, smooth and gentle arc.
Four common wrong bending modes
In clinic, we can find that many people can't do the above correct bending. Four common problems may arise:
1) The lower thoracic spine bends and the hips move backward.
When people with limited hip flexion bend over, the lower thoracic vertebra bends, accompanied by the backward movement of the hip joint. This phenomenon may happen to people whose trunk is longer than their lower limbs.
2) The lumbar vertebrae are flat and the thoracic vertebrae are excessively bent.
If the normal flexion range of hip joint (70 ~ 80 degrees) is accompanied by lumbar flattening, but the thoracic vertebra is too curved, this phenomenon indicates that there is something wrong with the motion of the spine segment of the subject.
3) excessive backward movement of ankle joint, knee joint and hip joint
If the flexion of hip joint and spine is limited, it will be accompanied by excessive backward movement of ankle joint, knee joint and hip joint. This phenomenon may occur in subjects with limited spine movement and too tight or too short calf muscles.
4) excessive waist bending
If the subject's waist is found to be excessively bent when bending over, the subject may have a flat back.
△ Under normal circumstances, the lumbar flexion angle will not exceed 50 degrees. When bending forward from the normal lordosis posture, the first 25 ~ 35 degrees will return the lumbar spine to the central position, so the continuous bending forward movement of the body is only allowed to bend the lumbar spine, and the range is about 15 ~ 20 degrees. When a subject with a flat back bends forward from the middle position of the lumbar spine, it may cause the lumbar spine to bend beyond the safe anatomical range, thus causing damage to the ligaments and soft tissues supporting the spine.