Negative split calculator?

Real LR bros run by feel.

Cool stuff.

Garmin Connect lets you do a similar thing, even accounting for elevation changes on custom courses.

I have Garmin Connect, thanks for letting me know about this so I know to look for it!

You're welcome. It's called PacePro.

To break a 3:20:00 marathon, choose splits like 5% (39:41, 1:56:47, 3:10:52), 10% (41:17, 1:59:19, 3:11:19), or 1% (38:24, 1:54:45, 3:10:30). Customize for conservative or aggressive pacing.

Thanks Emma. I'm shooting to break 1:30 in the 1/2 and work on shorter distances before doing another full!

Speaking of negative splits, I recently ran a marathon after spending some time out from injury so I was pretty conservative over the first half(1:42). The second half I had much more energy that I thought was possible after so much missed training and ran a 1:33 second half (3:15 total). It was pretty dumb pacing, but with even splits, what do you think I could have run?

Assuming relatively flat, and that you truly used all your energy, something akin to 3:11-3:13 maybe.

Pacing matters a bit less than you think when you negative split cause even if you end up splitting 1st too easy and 2nd half harder you'll pretty much have made up what you slowed in the first half, but if you had a positive split instead then pacing would have helped much more because that means you blew up and slowed a lot.

So you probably could have run 1:36 each half and paced well.

Of course it's also a bit different if you felt the race ran out too soon for you to properly empty the tank, then maybe it could be quite a bit quicker.

When are you hoping to break 90? That’s a pretty big leap from the 3:19-3:21 shape you were in last fall. Have you been crushing training the last couple of months? Good luck man. Keep building.

Sorry if this is just stating the obvious, but of course you can hit a limit fairly easily, especially in the case of substantial miscalculation like that runner faced in not having a good understanding of fitness because of injury. A runner obviously can’t run the second half at true half marathon pace.

So you’re right about that 3:12 being good at a roughly even 1:36 split (especially fairly even GAP, with early few miles a bit slow with that time regained gradually over a greater number of miles late). But assuming there’s no wildly great difference in elevation, by around a 1:39 first half, it would get increasingly harder for a real 3:12 fit runner to close fast enough to hit 3:12. Anyone who might, for example, go 1:41/1:31 is fit to run faster than 3:12.

Thank you! Shooting for 1:30 or faster on 10/20/24.

Jecht - did you see the video that was made addressing your thread?