In bodybuilding theory, RM is used to indicate the maximum number of repetitions that a load can do continuously. For example, an exerciser can only lift a heavy object five times in a row, so the heavy object is 5RM. The research shows that: 1-5RM load training can thicken muscles and develop strength and speed; 6- 10RM load training can make muscles thick and strength speed increase, but endurance growth is not obvious; The muscle fibers of 10- 15RM were not obviously thickened, but their strength, speed and endurance were improved. After 30RM load training, the number of muscle capillaries increased, and the endurance was improved, but the strength and speed were not improved obviously. It can be seen that the load weight of 5- 10RM is suitable for bodybuilding training to increase muscle mass.

The above is the theory. I am a city sports coach. If you want to gain weight, you have to gain weight. You can only do 8 weights at a time when you increase to the limit. Then do it in groups, the more the better. I hope my answer is helpful to you.