While training with a rowing machine is extremely effective for the cardiovascular system as well as for strengthening your arms, shoulder and your back, you should start carefully if you never rowed before and aren’t used to this kind of movement. Rowing should always be done in a flowing movement, so setting the resistance of your rower to a lower level and then training how to row properly first is a good idea.
Start with pusing off with your heels and make sure your back remains straight, you can lean back slightly but you should never lean forward. Once your legs are straigt, pull the handle or handles, depedning on the kind of rowing machine, till it reaches your upper stomach. Keep body tension while doing so and never try to wrest the handle backwards. Most of the power needed will come from your legs, you back should always remain in an upright position, you arms have to stay straight until your legs are fully streched. Trying to pull too heavily with your arms may cause pain in your shoulder or back, so don’t do this, use your whole body and use the tension to pull back the handle.
Learning how to row properly won’t take long, but it’s essential to learn it first before working with alot of resistance. Also keep in mind that this isn’t classical strengh training, so rowing for 5 minutes won’t be an effective training. The longer the better, if in doubt use less resistance, but prolong the time you workout. Always make sure you feel comfortable and don’t try to force things, as a beginner there is nothing bad in starting with almost no resistance. To stay motiviated, having fun while training is essential and rowing isn’t weight lifting.
To exercise several days a week is advisable for the maximum effect, but always give your body and muscles a day or two in between training sessions since muscles grow while you rest, not while you train and proper recreation time makes training alot more effective for home use.