Is a “Hybrid” McMillan Calculator Best for You?


You know how the McMillan Calculator works. You put in your current fitness (either a recent race result or an estimate) and then the Calculator determines training paces that will challenge your body to advance to a high fitness level. The genius, if I may say so, is that it calculates precisely just how much added training stress each of the four training zones can take to push you enough but not too much.

For most runners, using it in this way works perfectly. That’s because most of us are “combo” runners, meaning that across race distances from the mile to the marathon and within each training zone (endurance, stamina, speed and sprint), we are pretty “equal”. We may tend toward shorter races or longer races or do slightly better in short/fast workouts or long/steady workouts but overall, we have a good combination of all four fitness traits.

I’m a good example. If you put in my 5K PR of 14:55, you’ll see that my actual performances at other distances (handwritten) are pretty close to the predicted performances. For example, the calculator will predict from my 5K of 14:55 that I could run 4:17 for the mile (I’ve run 4:13), 30:59 for 10K (I’ve run 30:57), 1:09:04 (my PR is 1:10:28) and 2:25:21 for the marathon (my PR is 2:31:58). From this quick survey of my PRs, you see that I’m pretty close across the board but tend to match or exceed the prediction in the shorter, more speed oriented races. That’s why I call myself a combo-speedster – a runner who is pretty good across all aspects of fitness but do a little better in the speed department compared to the endurance department.


One note: I’ve been lucky to compete from a young age and to compete in all distances, from middle distances of 800m to 5K in high school up to longer distances including the marathon when I was still in peak shape in my late 20s and early 30s. This gives me a really good look at how I compare across distances. If you, however, have never competed on one side of the race spectrum (e.g., you got started during the marathon boom and never really did much speed work or shorter races) then your evaluation may be slightly skewed since you don’t really know your capabilities in shorter races until you spend some time working on your speed and competing more frequently in these races.

That said, I think you see my point. I can insert my current race times (shown below) and get a perfect set of training paces for all my workouts. Since I’m a combo-speedster, I usually find that I’m more on the faster end of the suggested pace range in the speed and sprint workouts whereas I’m in the middle or slow end of the pace range in endurance and stamina workouts.

What if, however, you are not a combo runner but much more of a true speedster or endurance monster? With these athletes, I use a “hybrid” McMillan Calculator. Here’s a real-life example:

A few years ago, I coached a young woman named Jill who is a true endurance monster. If you put her marathon PR into the McMillan Calculator, you’ll see that her long distance races match up but she can’t come close to the predicted times for short races no matter how much we tried.


What happens with athletes like this (or ones who are on the opposite end of the spectrum and true speedsters) is that they can easily hit the training paces for the training zones that match their type but have to kill themselves just to hit the slow end of the range in the training zones that don’t match their strengths. For example, Jill could easily hit the paces for the endurance and stamina workouts but clearly had to strain to hit even the slow end of the range for speed and sprint workouts. Obviously, this isn’t optimal training for an athlete like her. It’s overtraining.

So, for Jill, I created two sets of training paces using two race times. For endurance and stamina workouts, I used her marathon time since these training zones fit her strengths as a runner. For speed and sprint workouts, however, I didn’t use the paces derived from her marathon time. Instead, I put in her 5K time and used the speed and sprint paces from this time. Below, you can see a side by side comparison of the difference in pace ranges from these two calculations.


For Jill and runners like her, I simply use this “hybrid” version of the McMillan Calculator – some paces from one race distance and some paces from another race distance.

The end result is that her training was now optimal, not just for training zones that matched her strengths but also for those zones that she had struggled with before. The benefit of using this Hybrid McMillan Calculator was that her training was so dialed in that she not just got a whole lot fitter but went on to win the US Marathon Title in our second year working together. Not bad and clearly shows that for runners who are true speedsters or endurance monsters, they need to implement this hybrid system to dial in all workouts and get the most from each training zone no matter if it’s your strength or not.


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Written By Greg McMillan
Called “one of the best and smartest distance running coaches in America” by Runner’s World’s Amby Burfoot, Greg McMillan is renowned for his ability to combine the science of endurance performance with the art of real-world coaching. While getting his graduate degree in Exercise Science he created the ever-popular McMillan Running Calculator – called “The Best Running Calculator” by Outside Magazine. A National Champion runner himself, Greg coaches runners from beginners to Boston Qualifiers (15,000+ and counting!) to Olympians.

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