@sakhi,
If you were to ask me, I'd prefer treadmill. I suggest you should try to compare the benefits of the two before making a decision. Both of them helps you strengthen your cardiovascular system.
Treadmill strengthen your bones and prevent or manage osteoporosis. And if you are recovering from back, hip, knee or ankle injuries, you may have some stiffness in your joints. Doing a gentle walking program on a treadmill will help to loosen your joints and regain flexibility.
However, rowing machines invokes all the muscles of the body and trains them evenly. Rowing burns calories and is an excellent adjunct to a weight loss program. And its a popular home-exercise equipment choice because they come in compact sizes
Hope this helps
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