Rugby players tend to be bigger than the average human.
Your BMI index determines your obesity. Interestingly, at 5'10" and 200 lbs, my BMI is 28.7.
I'm considered over weight, even though I have a washboard stomach. (I do, here's why.)
So, an athlete could look to be in the over weight category. The solution is to make sure the insurance company knows about your regular exercise program. Don't be afraid to attach a cover letter with your application, or an MD's note saying how great in shape you are.
Remember, you buy health insurance with your HEALTH, not your money.