How do runners adjust their pace to climbs and descents?
Sections marked uphill, downhill or near level in the supplied course profiles have different observed pacing patterns. This is an exploratory alignment with a route proxy.
The route files mostly describe recent editions. Their historical validity is unverified, so this cannot measure the effect of the hills actually run in every year.
How we measured it. Join a unique supplied course segment by city and exact checkpoint distance. Classify net grade above +0.15% as uphill, below −0.15% as downhill and the remainder near level. At each distance, plot median individual section pace relative to that runner’s full-marathon average.
Full methodology & sources
The course profiles use GPX geometry and digital elevation models, sometimes smoothed over 2624.7 ft. Net grade conceals mixed climbs and descents; bridge decks, tunnels and route changes may be wrong. Historical races are compared with the available city profile as a proxy only. Different terrain groups contain different courses and fields; no causal hill penalty or physiological effort is inferred.
Use complete, strictly increasing elapsed checkpoints at 3.11, 6.21, 9.32, 12.43, 15.53, 18.64, 21.75, 24.85 and 26.22 mi. Clock strings must parse as H:MM:SS or M:SS. No missing splits are interpolated.
Remove exact duplicate race records, ignoring database IDs, ingestion timestamps and source URLs. Retain finishes from 90 minutes to 12 hours with every section between 3.22 and 32.19 minutes/mi. These quality filters can exclude genuine unusual performances; the analysis describes this eligible cohort, not every entrant.
Full source records are available in public GitHub Releases. These chart tables require at least 100 eligible observations per cell for estimate reliability. Counts refer to finishes, linked pairs or event observations as specified in that answer.
These are observational results. Fitness changes, intentions, training, selection into the dataset and unmeasured conditions can explain differences. Outcome percentiles describe variation among performances, not confidence intervals or advice about the best strategy.
Apply the reviewed source-quality edition exclusions for this exact export after the timing checks. Known invalid split grids, incomplete ingestion, unreconciled HOLD editions and a selected top-finisher field do not contribute to the analyses or prior benchmarks. Report source exclusions separately; an already invalid timing row is not counted twice. Missing age or recorded gender alone does not exclude an otherwise eligible finish from the overall cohort. Other sparse editions are not declared incomplete merely from their size.
Observed pace alongside supplied terrain classes
Pace difference (%) · higher is slower
Points average the preceding section. The final section is 24.85–26.22 mi; lines do not locate pace changes within a section.
View exact values and sample sizes
| Course section | Observed pace alongside supplied terrain classes | Observations |
|---|---|---|
| 0–3.11 mi | -3.6% | 363,514 |
| 3.11–6.21 mi | -5.2% | 142,672 |
| 6.21–9.32 mi | -4.9% | 96,628 |
| 9.32–12.43 mi | -3.4% | 23,152 |
| 12.43–15.53 mi | -0.7% | 801,387 |
| 15.53–18.64 mi | 1.6% | 494,451 |
| 18.64–21.75 mi | 8% | 7,853 |
| 21.75–24.85 mi | 9.7% | 947,400 |
| 24.85–26.22 mi | 5.1% | 513,418 |