Human Limits

Exploring performance and health with Michael J. Joyner, M.D.

Photo of Michael J. Joyner, M.D.

Archive for July, 2015

A Roadmap To Better Health

It is finally here! Our data packed and evidence based book on major issues affecting the health of the U.S. population, including smoking, diet, physical activity, and the policy options to move us in the right direction is now available. You can download a no cost PDF version of this book (and other books from the Roadmap series) from the website of the Arizona State University’s Healthcare Delivery and Policy Program. A paperback version is also available from Amazon (no profits to us). We hope that this book will be useful to a wide range of people interested in the topics of population health, physical activity, exercise and diet. We have focused on basic data related to these topics and what policies might be used to promote healthier lifestyles for both individuals and society as a whole.



Is Dibaba’s 1500m Record “Believable”?

A couple of weeks ago Ethiopia’s Genzebe Dibaba broke the women’s world record for the 1500m run with a time 3:50.07. The believability of this performance will certainly be questioned because most of the women’s world records in track and field have been stagnant for decades and date to the era of industrial strength doping in the 1980s and 90s. The 1500 record was set by a Chinese athlete in 1993 who was almost certainly doping. Many of the men’s distance running records are also “old” and occurred after the emergence of the blood boosting drug EPO in the late 1980s and before the advent of better (but far from perfect) drug testing regimens in the later 2000s.

A reasonable rule of thumb is that world records in women’s middle and long distance running “should” be on the order of about 11-12% slower than men’s. This is based on the fact that maximal aerobic power is typically that much lower in elite women than men, while other key physiological factors related to lactic acid build up and running efficiency that determine running performance are generally similar. The current fastest time by a man for 1500m in the pre EPO era was set by Said Aouita at 3:29.46 in 1985! The best time since drug testing got better is 3:26.69 by Asbel Kiprop of Kenya set earlier this year (the world record for men is 3:26 set by Hicham El Guerrouj in 1998).

Historically even better performances, but not faster times, were achieved by Jim Ryun and Kip Keino in the late 1960s. Ryun ran a 3:33.1 on a cinder track at the LA Coliseum in 1967. It was also hot that day. A modern optimally tuned track might be worth 3% and if you adjust Ryun’s performance you get an estimated time of about 3:26 and change.

An even more remarkable performance came a year later when Kip Keino ran 3:34.9 at high altitude to win the gold medal at the Mexico Olympics. Mexico City has an altitude of almost 7,400 feet (2,250m), and the best data suggests that lack of oxygen at that altitude should reduce aerobic power by about 10%. Now Keino was altitude adapted because he had spent his life in the highlands of Kenya, but adaptation only gets you so much. So if we are conservative and adjust his performance by 5% an estimated time just over 3:24 seems “possible”.   Old school “point tables” from the 1960s and early 70s also suggest that the 5000m times run by Dibaba and also her world record holding sister equate to times under 3:50.

Which brings me back to Dibaba and the women’s 1500m record, her time is a little more than 12% slower than what Keino might have run and between 11 and 12% slower than the projection for Ryun. It is just over 11% slower than the best time for men since drug testing got better. There are all sorts of reasons to be suspect of any world record in sports like track and cycling and the East Africans have done their share of doping. However, given the analysis above, Dibaba’s record seems like it is at the edge of believable to me.