How fast will you be on that hilly course?

Or in that heat? On that trail? At that altitude?

These are questions that have plagued me for a few years as I have ramped up the marathoning and begun taking on challenges a lot more varied than the typical flat, fast, smooth road course run on a 50-degree day in Fall.

Here in Virginia, I end up running a lot of trails. It’s hot. They’re hard. And the hill running here may not be at altitude, but the short, choppy climbs are nearly as bad as anything I’ve faced in Chamonix or Zermatt. (I can think of at least 3 Virginia marathon courses with climbs lasting miles and topping out at 1500ft of vertical).

Sure, you can head into a course like that and just wing it. But winging it can end badly. I always want to know just how much the heat and climb and trail will slow me down, so I can at least keep my pace in the right ballpark.

Or, consider training days. We all know we need to run the right pace to get the desired physiological adaptations, be that strength building, VO2 max development, or lactate threshold work. But if my tempo run pace is 6:22, what should I be doing on a 70-degree day?

Until I updated Run Ranger, I never found a calculation tool, app, website or anything else that could do this job with anything resembling accuracy.

Sure, I found a variety of tables and rules of thumb in books and on web sites that suggested, say, adding 30 seconds a mile to your pace if running at XX degrees. That is, of course, nonsense. Thirty seconds? So, if I’m a 3-hour marathoner, I add 30 seconds, and the 4 and a half hour guy or gal? What do they add? How about the Kenyan transplant who now lives in Arizona and is finishing up in less than 2:20? I’m pretty sure he’s not adding 30 seconds too.

You get the idea.

With nowhere to turn, I decided to do this job myself. Step one (one through 100, really) getting data and figuring out what the proper pace adjustments should be. This was the bulk of the work. There’s very little research on the subject of pace-changing conditions, and what there is isn’t often based on real-world data. Some of it’s decades old, and often, the results were presented as rules of thumb rather than mathematical expressions that could be adapted to any given pace. I gathered up as much of this information as I could, distilled it, and supplemented it with real-world results from tens of thousands of real running efforts. I crunched the numbers and then tested the resulting algorithms against other real world results, including my own experience (painstakingly documented over the years with weather, heart-rate, and GPS tracks) in 48 marathons and hundreds of training runs at all temperatures, on all surfaces, in many parts of the world.

I’m convinced that I’ve got the best algorithms in any running calculator you’ll find anywhere. And I’m pretty sure you’ll never find all of these potential offsets integrated in one calculation routine as in the latest version of Run Ranger.

In addition to the obvious (temperature), I’ve included the heat index – modifying it specifically for runners, who begin to feel the effects of high humidity long before the usual, non-active, shirtsleeves citizens for whom the heat index was designed.

I’ve worked in a variety of running surfaces, from a smooth track (which is quicker, but only slightly, and only for a while) up to rock-hopping trail courses and deep sand.

I’ve got climb and descent modifiers, but be warned, these are the modifiers most prone to wide variation. Under normal conditions (i.e. grades up to 5% to 7%) these calculations should hold pretty well, but as the grades ramp up to inclines so steep that they begin to separate the runners from the walkers, the predictions will become less reliable. (I’ve got a solution in mind for this problem, but it’s considerably more complex, and will take time to implement.)

Finally, there’s altitude. Altitude and the related oxygen deprivation are another area where the predictions will be wide of the mark more often, simply because altitude response is so wildly variable among humans. Moreover, the level of acclimatization makes a huge difference. Run Ranger’s current altitude algorithms presume that the runner is fairly well acclimated to altitude. In the next release, I will have a way for individual runners to tweak this setting to match their own, personal acclimatization, as well as for heat resistance, climbing strength, sure footedness, and more.

Fine, fine. How does it work?

Consistent with the original Run Ranger workflow, you begin on the pace calc pivot page by entering a distance and time or distance and pace and hitting the calculator button. If you are trying to figure out how fast your next marathon will be on a hillier course on a hotter day, enter your recent best marathon on a day with normalized conditions. Next, swipe right to bring up the perform page. Select your target surface, temperature, climb, descent, and altitude and bang, you’ll have your adjusted time and pace at the top of the screen.

How good is it?

When I ran the Miami Marathon last week (flat course, so just a temperature adjustment), I shot for a 3:01 effort, which is what I ran in a recent marathon on a flat course on a 40 degree day. Run Ranger’s marathon time prediction was within 1 second of the time I actually ran in Miami.

Obviously, it’s not going to be that accurate all the time, but even I couldn’t believe it when I checked the race temperature and did the final calculation (while sipping a Bloody Mary poolside at the Epic Hotel.)

I hope you find the new functions useful.


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