Positive Splits Aren’t a Mistake
Although textbooks unanimously recommend negative splits, in the following 4 scenarios, a positive split is actually the smarter strategy:
Scenario 1: Course Terrain That’s Easier Early, Harder Later
For example, the Taipei Marathon has a flat first 21K and a bridge-heavy second 21K. Or a trail race with downhill early and uphill late.
Correct Strategy: Execute an even effort based on “Grade-Adjusted Pace (GAP),” and your actual finish times will show a positive split.
| Distance | Actual Pace | GAP Pace |
|---|---|---|
| 0-15K (Flat) | 4:55 | 4:55 |
| 15-30K (Slight climb) | 5:10 | 4:55 |
| 30-42K (Bridges) | 5:20 | 4:55 |
Total time shows a positive split of about 8 minutes, but the actual effort is even.
Scenario 2: Races Where Temperature Rises
Taiwan’s winter marathons start at 6 AM at 14°C and reach 22°C by 9 AM. For every 2°C rise, pace drops about 5 sec/km.
Correct Strategy: “Bank time” during the cooler hours and allow a natural slowdown later. For example, targeting 3:30, run the first 25K at 4:55 and accept a drop to 5:05 for the last 17K—you can still hit your goal.
Scenario 3: Short Distances (5K/10K)
The optimal split for short races is actually a “slight positive split + finishing kick.” Reason: a 5K doesn’t require glycogen preservation, and if you run the first kilometer too slow, you can’t make it up later.
Optimal 5K Split Example (Target 20:00):
- 1K: 3:55
- 2K: 3:58
- 3K: 4:02
- 4K: 4:03
- 5K: 4:02 (including the kick)
Scenario 4: High-Altitude Races
Above 1,500m, partial oxygen pressure drops and you get more breathless as you go. Even at an even pace, the later stages feel harder. Allow the pace to drop 10-15 sec/km in the second half, resulting in a positive split overall.
Distinguishing “Strategic Positive Splits” from “Failed Positive Splits”
| Characteristic | Strategic Positive Split | Failed Positive Split |
|---|---|---|
| First-half vs. second-half difference | 2-4% | 8% or more |
| Second-half feeling | Tired but manageable | Major slowdown, painful |
| Heart rate trend | Linear increase | Peaks early |
| Feeling after finishing | Satisfied | Regret starting too fast |
Conclusion
There’s no dogma in pacing philosophy. A positive split can be a smart strategy or a beginner’s mistake. The difference comes down to whether you “actively chose it” or “were forced into it.”
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