There are many reasons for abdominal training back pain, the main reasons are lactic acid accumulation, muscle strain, lumbar disc herniation and so on. 1. Lactic acid accumulation: patients who have not trained for a long time, when they suddenly carry out high-intensity abdominal muscle training, the accumulation of lactic acid products is too much, which will trigger the phenomenon of muscle soreness. 2. Muscle strain: When strenuous activities of the waist are carried out for a long time, the muscles will be stretched for a long time and strain will occur, which will lead to low back pain. 3. Lumbar disc herniation: patients with disc herniation will aggravate the herniation phenomenon after a large number of abdominal muscle training, which will lead to low back pain. There may be other reasons for abdominal training low back pain, such as trauma, incorrect training methods, etc. It is recommended to consult a doctor in a timely manner, improve the relevant examination, and carry out targeted treatment and therapy after the cause of the disease is clear.