Each group can rest for 30 to 90 seconds and practice for 48 hours at a time: 48 to 72 hours after the second local muscle training. If high-intensity strength training is carried out, the interval between two trainings of local muscles is not enough, especially large muscles. But the abdominal muscle is an exception, which is different from other muscle groups and must be stimulated frequently, at least four times a week, each time about 15 minutes; Choose three exercises that are most effective for you, and do only three groups, 20-25 times in each group, all exhausted; The interval between each group should be short, and should not exceed 1 minute.