This has been the year for me to question the experts: How much is enough marathon training? I’ve done my research, made my choices, and accepted the consequences. But how do you know you’ve reached the proper conclusion without also testing the limits to the opposite extreme?

Experts seem to agree that roughly 150 minutes of aerobic exercise and two days of strength training each week is a healthy minimum requirement. It always depends on something, however. If you want to lose weight, more exercise may be needed. Do you want to win a gold medal? Absolutely, more exercise is needed.

I just want to finish a marathon in the fastest time possible based on my age, sex, and genetic endowment. How much running does that require? It has been the 2016 question of the year.

On the other side of the coin, a guiding rule is to limit exercise to roughly 10 hours, or 600 minutes each week – a limit I have tested often. Sometimes it goes pretty well.

Several years ago I was cycling up to 50 miles each week and running 30 miles. I ran my fastest marathon that year. Two years ago, I went back to school and spent two days each week hiking, climbing, swimming or paddling in addition to marathon training. That year I set a new personal best time at the 10k distance, and achieved a 2nd place age group award in the toughest marathon I’ve run yet.

So I’ve been thinking, maybe the better question is not how many miles to run, but how much time should we devote to our dominant sport?

We Know MORE, But It’s Still 26.2 Miles

In 2007 Jonathan Beverly sorted through the marathon training articles published in Running Times for the past 30 years to find “the essential, core principles by which to make all those four-page, four-month, four-point-font charts simple.” While the details within the most popular marathon training programs have changed over the years, four elements of marathon training remained constant from that first 1980 article to 2007: mileage, long runs, speed work and tapering.

To use this data to answer my question of the year, I dissected mileage.

The experts seem to agree that how much mileage depends mostly on your goals, which in turn are dependent on how much mileage you can handle without injury. If you aspire to a sub 3-hour marathon, most coaches have settled on an optimum training range of 60-70 miles per week. Depending on the course difficulty, my marathon times are usually between 4:00 and 4:30 hours. These same coaches indicate 30-40 miles each week is all that is required to get me to the finish line. Indeed this is the most mileage I have run when training for some of my best marathon finishes, and is barely half the mileage I ran when training for my worst.

What if I run those 30-40 miles in 4 days instead of 6, or 3 days instead of 5? What if I supplement running with other sports? Will I be more fit?

Because cycling burns more calories than almost any other sport, I dropped to just 105 pounds and down a full dress size when cycling was added to my training regimen. And during the 2014 Fall semester of paddling rafts, kayaks and canoes, I completely eliminated core strengthening exercises because paddling strengthened my core better than any exercise I had ever done. In the absence of these diversions of years past, I have filled 6 days of every week this year with only running.

My friend, Jono, is training for his first marathon using the Jeff Galloway run/walk/run program, which calls for 3 days of running per week. Currently, Jono’s 3 days of running totals roughly the same mileage as my 6 days of running. Jono had said to me, “You only need to run three times a week – it should be fun!” I couldn’t stop thinking about his advice.

In the interest of running experiments everywhere, I have subjected the remainder of this season’s marathon training to another experiment in hopes of finally answering the question of how much. I’ve taken my trusty calendar out, erased the remaining 10 weeks’ schedule, and re-written 30-40 miles of running into just 4 days – allowing blissful extra days each week for the cross-training of my choice.

Stay tuned. . . again.