When starting a new workout program you must work on fundamentals of training first and foremost. What do I mean by fundamentals of training? Basic fundamentals of fitness include cardiovascular endurance, muscular strength, muscular endurance, flexibility and body composition. There are basic exercises that will help build a sound foundation for anyone looking to become more fit and active. This will help you get better results along with prevent injuries.
One of the major components of building a sound foundation is working the full ROM or "Range Of Motion" of a given exercise. When you work the full range of a motion you are safely working the ligament and tendon attachments as well as flexibility of the joints. When lifting heavy weight you want to be very careful in how much you push your range of motion. The heavy weight will put a lot of strain on the ligaments and tendons so be cautious.
When challenging your range of motion you MUST listen to your body. If you are just starting off with a workout program or you are getting back into it after a long break you will want to take it slow. Baby steps are the key to avoiding injury, you want to make sure the ligaments, tendons and joints are ready and able to go a certain distance.
Working the full range of motion has many benefits such as the increase in efficiency of your movements. You will be able to preform many different types of movements with max amount of force through the whole range as you get stronger and stronger. This will burn more calories and get you the results you are looking for!
On the flip side if you don't work the full range of motion your muscle will only be trained in that range decreasing your flexibility and possibly causing injury and pain.
The focus of a fitness routine is to keep your body strong and be able to enjoy life as we age. Working out should enhance our daily lives so it is imperative to do the things in the gym that will help our bodies be strong, stable and mobile.