① Body fat rate
In the case of high body fat, no abdominal strength training can create a vest line!
If the body fat of boys is more than 20% and that of girls is more than 25%, then the first step in practicing vest line is to reduce fat.
② Exercise time and amount.
Those who are usually busy with work or study and don't have much time to do sports will naturally spend a little longer, maybe two or three months or even longer, in practicing the vest line. If you can spare more time every day and devote yourself to the training of vest line, you may see obvious vest line in just one month under the condition of correct fitness. In addition, those exercisers with high exercise intensity will also practice vest line faster than those who only practice primary movements. If you can correctly use abdominal muscles to stimulate abdominal muscles during training, you will get twice the result with half the effort.