With a lot of machines cluttering up the exercise scene, you need to find out what amount of exercising can be done on a rowing machine. It is certainly not safe at all if you start doing your workout without the expert advice of a doctor. You might be actually overdoing it, without even realizing that you are. Once you have over-exercised yourself, you will find that you have done a lot of damage because of the use of the  rowing machine . You cannot undo what you have done. So be careful when you begin to exercise.