If it is a normal sport, such as running and playing ball, it doesn't matter how old you are. However, if it is some high-intensity strength training, such as weightlifting training in the gym, it should not be done too early, at least after 16 years old, otherwise any tissue damage will have a great impact on future physical development. If you are a middle-aged worker, you should also pay attention to the intensity to prevent the cervical vertebra and waist from being injured in long-term compression, otherwise it will affect your work. If you are old, as long as you can do sports, the problem is not big.