In the gym, I often hear this sport do several groups ... What does this mean?

When you say 15/ group *5, you mean each group 15, * * * 5. And so on.

In the gym, if you want to exercise your body shape or muscles, you'd better have two to practice with you.

On the one hand, you can be protected when you do heavy strength (you also need to protect the people you practice with)

On the other hand, 2-3 people take turns to practice, and there can be appropriate rest time in the middle.

If you exercise your body, be gentle and do more.

If you practice muscles, you should constantly hit your limit weight, not too many times.

These hopes will help you.