The principle you have mastered is that muscles will stop growing after being stimulated by the same weight for a long time, and muscles in the same part will become stiff after repeated stimulation.

So every time you do muscle training, make sure to warm up first, and then start with lighter weight. After each group (for example, 12 times, or depending on your muscle fever or limit) completes 30 seconds of training, the weight of the next group is higher than that of the previous group, and so on, until it reaches a relatively heavy weight (for example, it can only be done 5 times or less) to better stimulate muscles.

Another training method is pyramid structure, starting from light to heavy, such as five groups, and then from heavy to light, five groups. In fact, although the last few groups are getting lighter and lighter, they are different from the lightness you started practicing, which will stimulate muscles and play a certain protective role. Generally, squats do pyramid structure training.