The Beauty of the McMillan Running Calculator

One thing I've always liked when reviewing the prediction times using the calculator is the difference between the 20mi and full marathon paces. At my current goal the difference is 7 sec/mile.

For a 3 hr marathoner the difference is 8 sec/mi. At 4hr it's 9-10.

If that's not a reason to start conservative in a marathon I don't know what is - the numbers dont lie!

Ben Z wrote:For a 3 hr marathoner the difference is 8 sec/mi. At 4hr it's 9-10.

If that's not a reason to start conservative in a marathon I don't know what is - the numbers dont lie!

Pardon my lack of knowledge but I'm a relative newbie and would love it if you would elaborate. I don't want to miss your point.

Stephanie - I believe he's referring to the race pace (in minutes per mile) for a runner at a given fitness level who is running 20 miles vs. a marathon. Since the full is 10k farther, the pace will be slower, as your pace will decrease for any race as the distance increases. McMillan's calculator sets up "equivalents," meaning if you can run a certain pace for one distance, you should be able to run the "equivalent" pace at a different distance at your given fitness level. So, if you run a 3hr marathon, your pace is ~6:50min/mi for that race, but you could sustain a 6:42min/mi pace for a 20 mile run... You'd just blow up and slow considerably after that. Hence, even that minor 8 second difference could mean the difference between a perfect race and a terrible last 10k.

+1 good answer Mike -- those 8 seconds are killer

Mike MacLellan wrote:Stephanie - I believe he's referring to the race pace (in minutes per mile) for a runner at a given fitness level who is running 20 miles vs. a marathon. Since the full is 10k farther, the pace will be slower, as your pace will decrease for any race as the distance increases. McMillan's calculator sets up "equivalents," meaning if you can run a certain pace for one distance, you should be able to run the "equivalent" pace at a different distance at your given fitness level. So, if you run a 3hr marathon, your pace is ~6:50min/mi for that race, but you could sustain a 6:42min/mi pace for a 20 mile run... You'd just blow up and slow considerably after that. Hence, even that minor 8 second difference could mean the difference between a perfect race and a terrible last 10k.

Exactly. Don't get greedy despite feeling fresh from the taper. You'll pay for it if you are not careful.

Awesome explanation Mike!! Thanks for explaining this to me!! I'm going to mark this thread for future reference.