What is a negative split?

Running the second half of a race faster than the first half. In marathons, a true negative split means sub-21:05 for the second 21.1 km when the first half took 21:06. Most world marathon records are run as slight negative splits.

Why is negative splitting recommended for marathons?

Going out too fast depletes glycogen rapidly and causes early-onset metabolic acidosis. A conservative first half preserves glycogen, maintaining pace in miles 18-26 when most runners hit the wall.

How much slower should the first half be?

A 1-2% slower first half is typically recommended. For a 3:30 marathon (5:00/km), start at 5:03-5:05/km for the first half, then aim for 4:55-4:57/km for the second half.

Marathon Negative Split Pace Calculator

Calculate first and second half pace targets for a negative split marathon strategy, where the second half is run faster than the first, for optimal energy management.

Core Tools

Distance covered in 12 minutes (meters)

🏅 Sports Note: These calculators provide estimates based on population data and validated formulas. Individual results vary by physiology, training level, and testing conditions. Consult a qualified coach or sports scientist for personalized guidance.

How to Use

Enter the values for the scenario you are assessing. Calculate first and second half pace targets for a negative split marathon strategy, where the second half is run faster than the first, for optimal energy management. Use the negative split pace result to inform your calculation.

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Marathon Negative Split Pace Calculator

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Frequently Asked Questions

What is a negative split?

Why is negative splitting recommended for marathons?

How much slower should the first half be?