Is it safe to run on the treadmill at 6 MPH for an hour straight?

Or does that sound dangerous to your body?

Thanks for any input.
Update: let's say, if I do this 5 days a week?
Update 2: BTW - to "john" - Thanks for the super duper deep paragraph you left, but no, I am not by technical terms categorized as "overweight". I am a 5 foot 3 female that is at a healthy weight of 115 pounds.
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