Equivalent Distance on the Track

One of Power Tool’s functions is to calculate the equivalent pace on the track. This corresponds to the speed on a flat road (in a windless situation) that the runner would have for a given power. In other words, if he runs at 300W at a pace of 4:00 on an athletics track, Power Tool will display 4:00 instead of the wattage. This is more intuitive, and makes it possible to use power-based training plans based on MAS (Maximal Aerobic Speed)

When running a marathon, this pace is generally the same as the one measured. The wind can certainly influence it, but the difference in altitude is generally so insignificant as to be negligible on most courses. Trail running is a different matter, and the difference in altitude is such that it becomes equivalent to adding distance. A classic approximate formula is to consider that 100m of additional ascent is equivalent to 1km more.

This is fairly approximate, but the power allows a slightly more relevant calculation. Indeed, we can consider that the equivalent distance on the track is :

$$ \frac{Mean\ Speed\ on\ track}{Mean\ speed\ measured} \times Distance $$

This calculation gives a more realistic estimate of the equivalent distance covered.

Here’s an example of how it works in practice. I ran a portion of the Mac VI race. We ran 15.6km with a 670m elevation gain at an average pace of 7:55. The equivalent pace on the track was 6:23. This gives us the equivalent distance on track:

$$ \frac{9.4km/h}{7.6km/h} \times 15.6km = 19.3km $$

The main benefit of this measure is to manage the weekly load of long sessions in hilly areas a little better. Indeed, when following a training program, it’s not uncommon for a planned outing to be a 15km run. But, with a steep gradient, doing your 15km is more demanding than on the flat. Power Tool can now be configured to display this equivalent distance during the session and, of course, record it in the session on Garmin Connect.