If the best choice for muscle training is the gym, although you can use dumbbells or sit-ups and push-ups at home to get the effect of muscle training, it is definitely not as effective as the gym and can be fully developed.

As for the prevention of injury, it mainly depends on whether your exercise is reasonable. If you have bad habits, you may get hurt even if you exercise at home with your bare hands. The key to prevent injury is to warm up fully and step by step when carrying weight.