I can run 1 mile at about 6:30 pace and be pretty spent at the end but recover quite quckly
At 7:30 I can keep going to about 8 miles and be pretty spent at the end recovery will take a few hours
At 7:45 I can do a half marathon and be pretty spent at the end , recovery will take a few days
However that doesnt tell the full story, I recently started a 10K at the back of the group (had to take a wizz a few minutes before the start) and busted a gut catching up to where I felt I was running with people around my pace and felt like puking at the finish despite being a couple of minutes off PB time.
So planning my first marathon..
Am I better off being conservative and run a slower pace on the first half and try for negative split second half if my legs still have it in them
Run a little faster (say 15 second a mile faster pace) on the first half as I'll likely be tired on the second half anyhow (likely pace 3:30 - 4:00 range, calculator predicted is 3:30 but that seems optimistic to me)
Go for an arbitrary steady pace based on online calculator predictors from my half pace times and hope I dont die in the last 6 miles?