[Scott Johnston]

Great question Theodore.

I think it might be a matter of semantics that is causing the disagreement.  At issue is how we define the aerobic threshold.

When I have said the marathon is competed at or a little above one’s aerobic threshold I am basing that on lactate readings taken during training sessions at marathon pace.  The elite marathoners that Renato Canova trained in the early 2000s were holding steady at around 2.5mMol/L of blood lactate concentration.  While there are some differences between sources most place the aerobic threshold between 2 and 2.5mMol/L

Canova was very open in showing the data on his athletes.  One in particular Moses Mosop ran a 2:03 so certainly in the speed realm of today’s top marathoners.  I have run across this number in writings by other coaches of top marathoners and at least one study (but I will have to do some searching to find those sources).

It is entirely possible that your friend was able to have lactate levels in that same range at 89% of max HR.  Here is why:  Over the past 30 years  I have personally tested and observed that in very well-endurance-trained athletes the aerobic and anaerobic thresholds separated by as little as 4%.  An example is one 4 time Olympian Cross Country skier I coached whose aerobic threshold occurred at about 172bpm and his anaerobic threshold was about 182 and his max heart rate was 188.  So, his AeT occurred at over 90% of his max HR and his AnT at over 95% of max HR.  From a metabolic standpoint this athlete would be producing about 2.5mMol/L of lactate at his AeT but was able to produce over 18mMol/L during the finishing sprint of 15km race. These are the numbers I personally recorded.  From a metabolic standpoint this indicates a huge aerobic capacity coupled with the big anaerobic capacity of a good 800m runner.

I don’t think the marathon has become shorter. It is still 42km and while the elite times have dropped from around 2:10  twenty years ago to 2:05 now, I can’t see how that would dramatically affect blood lactate levels.  Lactate is after all a reflection of the glycolytic flux.  Every marathoner must husband his/her carb burn rate so as to not run low in the final stages of the race and be forced to slow dramatically.  This point you raised about the marathon getting faster so that it is now competed at a higher metabolic state than in the past got me thinking. I looked at the results of the New York City marathon over the past 30 years to see where a 2:30 (the speed of a top amateur male runner) would have placed someone.  That time would have placed you 45th in 1990 and 52nd in 2023.  In the years in between there is a good deal of scatter in the results but with a barely discernible upward trend.  So, I don’t think we can say the marathon has gotten faster for the vast majority of runners.  Only a tiny fraction of them are flirting with times faster than the historical winners.

In the end, I think the most important takeaway is that the marathon is an event competed at speed fueled almost entirely by the aerobic metabolic pathway and that training to improve the capacity of that system to produce ATP should be the goal.

Scott