Based on actual race data, we've done the analysis to create pace charts that reflect reality for the Chicago Marathon (and we've also done it for Marine Corps Marathon). We took the results of all 35,000+ finishers of the 2011 Chicago Marathon, and broke out actual split times across the board in three sets of analysis:
1. Overall Splits and Pace: All Runners
Let's look at the overall splits and pace data to illustrate. Starting on the right side of this table, note that the 2011 Chicago Marathon Average Finish Time was 4:40:39, averaging a pace per mile, overall, of 10:53.
Breaking that down to half marathons: all runners accomplished this time by averaging 2:09:54 in the first half marathon and 2:30:46 for the rest of the race. On a per mile basis, they averaged just under 10 minute miles, first half, and slowed to 11:31 per mile second half.
2. Complete Race, Each 5k Split: All Runners, All Ages, from 20 to 80+
But the real action is in the 5k race segments. For each 5k, we calculated the average split for the 5k segment, and also the pace per mile that was run within the 5k. In the first 5k, all finishers averaged 30:16, or a pace of 9:46/mile. By the time they reached 35k, they were running the 5k segment at 36:40, or 11:50/mile.
Now, it gets even better. We completed a comprehensive analysis by age, by gender, by 5k segment, and by half marathon splits for all runners in the 2011 Chicago Marathon. This is your pace chart. This data represents what's likely, what's possible, what's proven. And, of course, what's average. For Example:
You may well be a faster than average runner. Then use these pace charts as a starting point and modify for your realistic pace. If you think you'll run 5% faster than the data on the pace charts, make that adjustment across all segments. Then go out there and nail the splits throughout the course on race day.
With these more realistic pace charts, this presentation of what can be expected on the Chicago Marathon course, runners are far more likely to manage their pace, expectations, and endurance on the way to their best finish ever.
Taking the half-marathon analysis the next level, we developed first- and second-half splits for all age segments.