What causes weakness in the abdominal muscles on one side?

Under normal circumstances, weakness in one side of the abdominal muscles may be caused by long-term poor posture, insufficient unilateral exercise, abdominal muscle strain, lumbar disc herniation, or rectus abdominis diastasis. It is recommended to seek medical attention promptly, identify the underlying cause, and receive symptomatic treatment under a doctor's guidance. Specific causes are analyzed as follows:

1. Long-term poor posture: Prolonged side-lying on one side, slouching, or sitting for extended periods with the body leaning to one side can keep one side of the abdominal muscles in a chronically relaxed state, gradually leading to loss of strength. Daily posture should be corrected to maintain proper alignment while sitting, standing, and walking, avoiding uneven loading. Exercises such as wall-standing and seated abdominal contractions can actively engage the weaker side and improve muscular balance.

2. Insufficient unilateral exercise: Focusing primarily on bilateral abdominal exercises or neglecting unilateral training during workouts may lead to noticeable strength differences between the two sides. Targeted unilateral abdominal exercises—such as single-side crunches or single-leg raises—can help, ensuring that the weaker side receives equal or increased repetitions and intensity during each session.

3. Abdominal muscle strain: Overuse of one side of the abdominal muscles—such as from frequent heavy lifting or forceful coughing using only one side—may result in muscle strain and difficulty generating strength. Patients may take medications such as enteric-coated diclofenac sodium tablets, ibuprofen sustained-release capsules, or celecoxib capsules as directed by a physician to relieve pain.

4. Lumbar disc herniation: A herniated lumbar disc compressing a unilateral nerve root can interfere with neural signaling to the abdominal muscles, resulting in unilateral abdominal weakness. As prescribed, patients may use medications such as mecobalamin tablets, vitamin B1 tablets, or eperisone hydrochloride tablets to support nerve health and alleviate muscle spasms.

5. Rectus abdominis diastasis: Often caused by excessive abdominal expansion leading to separation of the rectus abdominis muscles on one side, impairing their ability to contract effectively. Mild cases may improve through diaphragmatic breathing and core muscle training; severe cases may require surgical repair—suturing the separated muscles back together—to restore normal function.

In daily life, avoid prolonged one-sided loading, maintain balanced physical activity, warm up properly before exercising, and avoid sudden excessive exertion. Regular core muscle training is also recommended to enhance overall abdominal strength and maintain stable muscular function.