Would it help if I said it is not a very practicable trip. First, i do not believe that many buses run, if any at all, on marathon morning from the resorts. One lane of the road between the Contemporary to Wilderness is closed for the marathon. Likewise, one lane from the back gate to MK through the Poly is blocked. There
may be an AK bus from the TTC during the event, but even then it is challenged to get out to the AK in a timely manner due to road detours.
If you are set for a Poly to AK hop, I would suggest a better option is to walk to the TTC and
-Hop the monorail to Epcot and bus over
- Hail a cab and take it to the AK.
In either case make darn sure you know how fast your runner is going. Note the time they pass Poly and divide that by 13. Then multiply that 17. In real round numbers if your runner is running at a 12 minute pace you have about 45 minutes to complete your travel or you miss them at AK. You get and extra 20-25 minutes if they are at a 16 minute pace.
I know that my DW has been able to make the hop only if she starts the trip when I pass TTC. Even then she walks from the TTC to the monorail and ends up in front of the AK with minutes to spare.
Take a look at the spectator tool, even Disney suggests not trying to make this leap.
http://espnwwos.disney.go.com/events/rundisney/spectator-tool
Sorry to be a cold splash.