Pacing Strategy: A Complete Comparison of Negative Split vs Positive Split

Introduction

Marathon pacing strategies can be divided into three categories: positive split (faster first half, slower second half), even split (same pace throughout), and negative split (faster second half than first half). When Kipchoge set the 2:01:39 world record at the 2018 Berlin Marathon, his first half was 1:01:06 and his second half was 1:00:33—a classic negative split. However, among amateur runners, over 70% run a positive split, with the second half slower than the first by more than 5% (known as “the wall”).

Physiological Differences Between the Three Strategies

Why Negative Splits Produce Better Results

From an energy metabolism perspective, fat is the primary fuel for the first 30 kilometers of a marathon, while the final 12 kilometers shift toward a higher proportion of glycogen/lactate as liver glycogen is depleted. Going out too fast in the early stages will:

• Deplete glycogen earlier (burning 5–8 grams more per minute)
• Cause cardiac drift to appear sooner
• Accumulate micro-damage in muscle fibers, reducing muscle strength in the later stages

Conversely, a negative split allows glycogen fuel to be distributed evenly, leaving enough energy to accelerate in the later stages even as heart rate rises.

How Amateur Runners Should Choose

Most runners are advised to adopt a “conservative even split + slight negative split in the later stages” approach:

• Km 1–5: 5–8 seconds/km slower than target pace, control starting excitement
• Km 6–32: maintain steady target pace
• Km 33–42: if feeling good, speed up 3–5 seconds per kilometer

Using a Sub 4 runner (5:41/km) as an example:

• First 5 km: 5:48/km
• Middle 27 km: 5:41/km
• Final 10 km: 5:35/km or faster

Practical Advice

First, the first 5 kilometers are a critical test of self-control. In large races like the Taipei Marathon and Tokyo Marathon, the crowded start makes it normal to be 10 seconds/km slower than target in the first 2 kilometers—don’t force your way through the crowd and waste energy. Second, cross-check your pace watch with perceived effort—if your RPE (rating of perceived exertion) has already reached 7/10 at 25 km, slow down; the premise of a negative split is having energy left for the later stages. Third, monitor heart rate zones: M pace should fall in Z3 (75–82% of max heart rate). If you’ve already reached Z4 at 20 km, it means you went out too fast—immediately slow down by 10 seconds/km to save yourself. Fourth, for Taiwan races such as Wan Jin Shi with rolling hills in the final 10 km, set your pace watch to “lap pace” with per-kilometer alerts to avoid charging too fast on the downhills.

Conclusion

Statistics tell us that negative splits are a common habit among PB runners. But the prerequisite for executing one is adequate training and starting self-control. Before your next race, write your target pace in three segments on your wrist (5:48 / 5:41 / 5:35), and trade discipline for results. Remember this saying: “In a marathon, the first 30 kilometers rely on your head, the last 12 kilometers rely on your heart.”

Related Reading

• Marathon Negative Split Pacing: The Discipline and Execution Details of Starting Slow and Finishing Fast
• The Negative Split Method: The Golden Strategy for Marathons
• Negative Split: Why a Faster Second Half Is More Effective Than a Faster First Half
• The Science of Marathon Pacing Strategies: Comparing the Benefits of Even Splits, Negative Splits, and Positive Splits