Meet the Man Behind Marathon Study: Jens Jakob Anderson


Marathon­ers tend to be a com­pet­i­tive bunch, whether they are com­pet­ing against oth­ers, them­selves, or both, so they are bound to find the latest—and largest ever—study on marathon results intrigu­ing. The study, lead by Dan­ish sta­tis­ti­cian and run­ner Jens Jakob Ander­sen, col­lect­ed data on 1,815,091 men and women of all ages in 131 marathons over the course of 5 years (from 2008–2014).

Per­haps the result get­ting the most atten­tion is that women are 18.6% more effi­cient marathon­ers than men. Although women’s times on aver­age were still 7% slow­er than men’s, women clear­ly ran a smarter race with more even split times between the first half and sec­ond half of their race. Men, on the oth­er hand, tend­ed to go out faster, hit ‘the wall’ at some point in the sec­ond half, and slow down dramatically.

Also inter­est­ing in the results were that, although men hit their speed peak at age 38 and women at age 24, it was the run­ners between ages 35–45 for both gen­ders who proved to be the best pac­ers. Chalk it up to matu­ri­ty per­haps? Marathon par­tic­i­pa­tion is clear­ly grow­ing in all age groups for both gen­ders, but the leader may sur­prise you—women 50+ are lead­ing with a near­ly 90% par­tic­i­pa­tion increase!

Our recent inter­view with Ander­sen dis­cussed some of the results, as well as the moti­va­tions for con­duct­ing the study and per­son­al respons­es from the results from the man respon­si­ble for the largest study ever con­duct­ed on marathon results.

THE CLYMB: What is your per­son­al inter­est and/or his­to­ry with run­ning?
Jens Jakob Ander­sen: Being 16 years old I enjoyed run­ning. I jumped the fence to the sta­di­um to train my inter­vals. I rarely par­tic­i­pat­ed in races; I loved the process, not the goal. What I enjoyed so much was improv­ing. The results were mea­sur­able! The rea­son I did­n’t become a world cham­pi­on was, as is the case with many oth­er young hopes, an injury. Today I still enjoy running—especially uphill. Run­ning in the moun­tains is one of the most plea­sured moments for me dur­ing my week.

THE CLYMB: What made you decide to con­duct this study in the first place?
JA: Ini­tial­ly, I was watch­ing some friends of mine at Iron­man Copen­hagen. They were great ath­letes, the best I know. Still they strug­gled hard in the last part of the marathon. I thought to myself ‘why do they suf­fer so much?’ How could they all be suf­fer­ing this much and slow down the pace this sig­nif­i­cant­ly? Imme­di­ate­ly after the race, I did some man­u­al cal­cu­la­tions for par­tic­i­pants at Copen­hagen Marathon and real­ized there was a pat­tern. Peo­ple spend so much time prepar­ing for a marathon, yet they are gen­er­al­ly way too optimistic.

THE CLYMB: What was the process of set­ting this study up (how long did it take, did you need any spe­cial per­mits or per­mis­sions, etc.)?
JA: The process was inspir­ing and full of learn­ings. The entire process took 6 months full time and involved peo­ple work­ing in 4 dif­fer­ent coun­tries. So, first I came up with the idea and asked my Fil­ipino assis­tant to dig deep­er into what races were avail­able around the globe. The result got back to me and then straight to Viet­nam, where I had a guy col­lect all the data into Excel sheets. 1.8 mil­lion results is quite a lot. Back to me, and straight to Poland, where a Pol­ish sta­tis­ti­cian worked out the spec­i­fied analy­sis. I would have had loved to make it myself, but Excel can­not han­dle that amount of data, unfor­tu­nate­ly (Excel only has 1 mil­lion rows max). Then back to me to ana­lyze the results and come up with the con­clu­sion. A long process. I learned so much, and I deeply appre­ci­ate all the peo­ple that were involved in this process.

New York City, USA — Novem­ber 07, 2010: Ath­letes run­ning dur­ing the 2010 ING New York City Marathon.

THE CLYMB: What was the most sur­pris­ing result for you in your study?
JA: Hon­est­ly, the most sur­pris­ing thing to me was that elder wom­en’s inter­est in marathon run­ning had been pick­ing up so fast late­ly. Over a 5‑year peri­od their par­tic­i­pa­tion rate has increased around 90%. That is mas­sive. True, marathons are get­ting more pop­u­lar, but the aver­age growth is nowhere near the growth of elder women. I am thank­ful for that and I love that they have tak­en the sport to them.

THE CLYMB: Had you par­tic­i­pat­ed in the study as a run­ner, where would you have fit into the sta­tis­tics?
JA: Ha ha, I would def­i­nite­ly be a clas­sic exam­ple of the aver­age run­ner, slow­ing down on the sec­ond part. If you ask 100 peo­ple if they think they are bet­ter than aver­age around, 67 will say they are. Fun­ny, but true. I am an enthu­si­ast and we tend to get caught in sit­u­a­tions like this. So I would def­i­nite­ly be slow­ing down even though I know how bad it would be for my per­for­mance. I would do many things not to be one of those guys slow­ing down, but in the end, I am sure I would slow down.

THE CLYMB: There are plen­ty of nay-say­ers out there about marathon­ing and how hard it is on one’s body. As some­one who has run them per­son­al­ly and well as stud­ied them for years, what is your response to marathon nay-say­ers?
JA: Actu­al­ly, I am not nec­es­sar­i­ly a fan of marathon run­ning. I am a fan of the process of train­ing so hard that you can accom­plish a marathon. To me, every­thing is rel­a­tive, and I can be just as inspired by the over­weight guy who lost 20 kg and then in one day biked 100 km, when he could­n’t have rid­den a bike 6 months ear­li­er. We all come from dif­fer­ent stages. Regard­ing marathon run­ning and the health ben­e­fits and chal­lenges, there are pros and cons. If I could choose only between a) every sin­gle per­son did marathon run­ning and ran 40 km/week and b) no one ran or did oth­er sports, I would vote for a). That being said, marathon run­ning is very hard on the body and I pre­fer short­er runs.

THE CLYMB: As an ultra-run­ning enthu­si­ast, I have to ask—are you plan­ning to study ultras next?
JA: Great ques­tion! The chal­lenge about ultra run­ning is that typ­i­cal­ly the event-mak­ers of ultra races are good at plan­ning very var­ied routes, which will make the data insignif­i­cant in many cas­es. I will have to find anoth­er angle to it, but I do def­i­nite­ly think it is interesting.