Practicing Pace: Trying a Cutdown Run

DJ Research is wrestling with his pacing strategy as he is preparing for the Marine Corps Marathon.  He sent me this Running Times article about pacing, which got me thinking...

I have no idea how I'm going to pace Richmond. The miles in the bank approach worked for Freedoms Run--where I inevitably had to pull it back in the second half of the race because of the hills--but Richmond is a completely different course: it's all flat. If I go out too fast, I will probably blow up badly later.

Ideally, I'd run a negative split - that is, I'd run the second half faster than the first.  Problem is: a) I'm not very good at starting slow and b) I don't have much confidence that I can run faster in the second half, even if I take it easy to begin with.

Anyone else tend to start too fast?  Or do you have any pointers on how NOT to start too fast?

I've never practiced running negative splits, so I thought three weeks before my marathon would be a good time to start (notice dripping sarcasm here).  Thanks to the Running Times article, I decided to do a cutdown workout during the last 6 miles of my 18 mile run.  No, I did not hire someone to berate me with insults as I ran.  A cutdown run is when you start the workout at 30 seconds slower than marathon pace, and drop 10 seconds with each mile.  My reasons for trying this were two-fold: 1) to get a sense of increased effort towards the end of a run and b) to get a sense of increased pace towards the end of a run.  Because running 8:20 m/m at the end of a run is a hell of a lot harder than running 8:20 m/m straight out of the gate.

These were the splits I was trying to hit.

I proudly wore my Freedom's Run Marathon race shirt, in all its lime-green glory.

The morning was gorgeous.

This picture does not do it justice.

I ran the first 9 miles slow, listening to the great crew over at Trail Runner Nation.  My pace hovered around 9:55ish.

Miles 10-12 I started focusing on my running and picked up the pace just a bit.  My pace hovered around 9:30ish.

I turned on the juice for mile 13 and felt pretty good.  But my pace was all over the place.  First I was running too fast, then I was running to slow, then too fast again.  I decided to just run what felt good.

Mile 13 - shooting for 9:05, ran 8:58.

Ok, I ran mile 13 a little faster than I'd hoped, so I tried to hold my pace for mile 14.

Mile 14 - shooting for 8:55, ran 8:51.

Yay!  Ok, that was good.  Tried to pick it up just a tad for mile 15.

Mile 15 - shooting for 8:45, ran 8:30.

Doh.  Ok, too fast again.  Tried to hold my pace for mile 16.

Mile 16 - shooting for 8:35, ran 8:21.

Ergh.  Too fast again!  Tried to hold my pace for mile 17.

Mile 17 - shooting for 8:25, ran 8:43.

Totally blew up at mile 17.  I couldn't hold my pace in the 8:20s at this point in the run.  Mile 18 was more of the same.

Mile 18 - shooting for 8:15, ran 8:40.

Still, I feel good about this run.  Now I know that I can run in the 8:40s towards the end of the race (I was doubting myself, thinking I probably couldn't run faster than 9:00s).  I'm not convinced that I should try for a negative split, though.  I'm kinda thinking that if I can blow up and still run 8:40s, maybe I should start out fast anyway?  I dunno.  Still pondering this one...

Do you practice pacing or train to run negative splits?  Have you ever tried a cutdown run?

Whats your race strategy?  Do you start fast and put miles in the bank or start slow and pick up your speed at the end?