Question 1

Why 1.06 and not another exponent?

Accepted Answer

It is Riegel's best fit to world-class records. Some coaches use 1.07 or higher for less-trained runners over the marathon, which gives slower predictions.

Question 2

Does it work for ultramarathons?

Accepted Answer

Riegel's fit covered efforts up to about four hours, so predictions beyond the marathon become unreliable.

Question 3

Can I predict a shorter race from a longer one?

Accepted Answer

Yes, the formula works in both directions, but a runner with mainly endurance training may not be as fast over 5 km as predicted.

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