Are you asking that the abdominal muscle defense circle of the fitness circle can't sense it? Check the battery, check the sensor, check the wear position, and contact the manufacturer or after-sales service center.

1. Check the battery: If the battery is used in the abdominal muscle defense circle of the fitness circle, please check whether the battery is low or exhausted. If so, please replace the battery.

2. Check the sensor: If there is something wrong with the sensor of the abdominal muscle defense circle of the fitness circle, it will lead to abnormal sensing. Please check whether the sensor is damaged or faulty, restart the equipment or contact the manufacturer for repair.

3. Check the wearing position: Please ensure that the abdominal muscle defense ring of the fitness circle is properly worn on the body. If you wear it in an incorrect position, it will affect the induction effect of the equipment.

4. Contact the manufacturer or after-sales service center: If the above methods fail to solve the problem, it is recommended to contact the manufacturer or after-sales service center for professional help and solutions.