Recently the MIT news office published an article on the science behind marathon running, based on the research of an MIT grad student. The goal of the research was to determine at what pace marathon runners can expect to run marathons. If they run too fast, the research can also estimate when they should expect to “hit the wall”, which is when muscles simply runs out of energy.
Although actual calculation of the pace requires some quantities that I don’t currently have – like VO2max and mass of my leg muscles – it is certainly full of facts I didn’t know.
- “The primary risk factors for ‘hitting the wall’ are male gender, running a maximum distance of 20 miles or less during training, and expecting to hit the wall.’ That means I had 2 out of 3 before reading the article, and I’m now a solid 3 for 3.
- “The power expended by a runner increases linearly with running speed [...] so the total energy required to complete an endurance event is cdm” where c is a constant of about 1 kcal kg-1 km-1, d is the distance run, and m is the mass of the runner
- “A runner [...] stores enough fat to fuel a race of distance
“, where
is their nonessential body fat percentage,
kcal g-1 is the energy density of fat, and
is the same as above.
- “Even the leanest athletes store enough metabolic potential energy to power multiple, back-to-back marathons, if only the working muscles could derive their power exclusively from fat.” A runner with 2% nonessential body fat (which is very low) theoretically has enough energy in stored fat to run over 100 miles.
- “Maximum fuel economy in endurance running is achieved at constant levels of exertion.” Notably, this doesn’t mean running at a constant pace. For example, you need to run uphill slower and downhill faster.
- “The likelihood of ‘hitting the wall’ during a marathon exhibits a peak around mile 21 followed by a sharp decline.”
The full article is a little bit hard to read, but definitely is loaded with good information.
