Running pace lab

What the numbers mean

Pace is how long you take to cover one kilometre or one mile. A 50-minute 10K is 5:00 per kilometre, or 8:03 per mile. Runners think in pace rather than speed because it adds up: hold 5:00 for ten kilometres and you finish in fifty minutes.

How race times are predicted

Give the predictor one recent race or time trial and it estimates what you could run at other distances. It shows two methods side by side. Riegel’s rule says that when the distance doubles your time grows by a little more than double, about 2.08 times. The second method works out your aerobic fitness from the result (the “VDOT” score coaches use) and finds the time that the same fitness would produce elsewhere. Both assume you train properly for the longer race: a fast 5K does not guarantee a marathon without the long runs.

Training paces

From the same result you get the paces most plans are built on. Easy pace is for the bulk of your running and should feel like you could hold a conversation. Threshold pace is comfortably hard, the speed you could hold for about an hour. Interval pace is hard, for repeats of three to five minutes. Repetition pace is faster still, for short efforts with full rests.

Using a pace band

A pace band is a strip of paper round your wrist with the time you should see on the clock at every kilometre or mile marker. Enter your goal, choose even pace or a negative split, print the band, cut it out and tape it on. Cover it with clear tape if rain is forecast. A negative split, where the second half is slightly faster than the first, is how most personal bests are run.

Common questions

How accurate is the prediction? Within a few percent between nearby distances, such as 5K to 10K. The further you extrapolate, the more your training decides the result.

How is maximum heart rate estimated? By the formula 208 minus 0.7 times your age, which is closer for most adults than the older 220 minus age. If you know your real maximum from a hard test, type it in instead.

Is the training plan right for me? It follows common coaching rules: build slowly, an easier week every fourth week, one longer run and one faster session a week, and a taper before the race. It cannot know your history or injuries, so treat it as a starting point and back off if anything hurts.