Isle Royal is ALL Rugged hiking trails, no roads. Also, not many trails cut across the island. Another thing, you need to make reservations through the National Parks Service to get on the Island. You can’t just go when you want. National Park service limits number of people allowed in certain time frame. Also, the Ferry Across to the Island from either Michigan or Minnesota is cash only (last I heard).
I’ve never been to Isle Royal myself, but I’ve known others who have, and said it was beautiful. Form what they’ve told me, the trails are definitely not ideal for running, as they were very serious hikers and said the trails were definitely difficult. Especially since you have to carry in your food and clothing.
Just thought I’d give you some info.