Fitness training routine combining rowing, treadmill cycling, is this healthy?

All things in moder. all things in moderation. in general the american college of cardiology recommend 60 minutes of get-your-heart-rate-up exercise 5 days/wk if you're in shape - 90 minutes if you're not. that being said - "extreme" athleticism might be bad for you and shorten your life. (100 mile marathon runs, climbing mount everest)