It is recommended not to exceed 1 hour at a time. It doesn't matter how long you exercise, what matters is the effect of exercise. Before exercise, you must do enough warm-up to avoid getting hurt easily. Relax after exercise and do exercise for 5 to 10 minutes to consolidate the effect of the exercise just now. Exercise and rest are very important, so should nutrition. Generally, after half a year, some muscles can basically be shaped.

Muscle growth requires not only exercise, but also adequate intake of protein. The interval time of dumbbell exercise is determined according to different parts of exercise. Such as large muscle groups: chest, back and legs, practice for 72 hours a day. Small muscle groups: arms and calves, practice 24 hours a day.

Generally, you have to do 4 to 5 movements, and one group does 8 to 12 movements. For example, chest push today, hunger tomorrow and shoulder push the day after tomorrow. Don't finish it in one day. The average person's muscles grow every 48 hours, and the initial effect will be seen after three months. It will be more obvious after half a year, and it will change a lot from one year to two years. But it must be guaranteed for about an hour and a half every day, not every day.