Posts from March, 2021
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March 19th, 2021

I am a mediocre marathon runner that hasn’t done any long-distances since Covid-19. But out of serendipity today, I was thinking about marathon and the interesting choices you would make during it.

Flat road marathon with support stations every half a mile is … bland. I probably have done that only twice, one in Maui, one in Denver. The only interesting bits for these two are hot temperature or the mile-high altitude. More interesting cases are trail runs with support stations every few miles. You have a lot of decisions to make along the way.

Elite runners probably can bulldoze through the trails. But for everyday runners like me, on the trail, the first decision needs to be made is, what’s going to be my pace for this segment? This is a function of your desired finish time, the elevation gain / loss for this segment and weather conditions. On a good day, at the beginning of the race, with massive elevation loss, you probably want to go as fast as you can. This is economical from the energy expenditure perspective. On the other hand, if there are a lot of ups-and-downs in the beginning, you probably want to keep a steady pace such that your overall finish time would be on-track.

The decision would be a bit different towards the end. If there are a lot of ups-and-downs towards the end, you probably want to take it slow on uphills and speed it up on downhills. This is more efficient energy-wise, and can still keep yourself on-track somewhat.

Besides questions on the pace, if there are a fairly reasonable number of support stations, you would need to make the decision on where to stop for refills. If there are only 3 support stations 6 to 7 miles away from each, you probably want to stop at every support station, since your 1L water bag may run out at probably 10-mile range. It is more interesting if there are not enough support stations such that you have to carry your own water bag, but sufficient number of them so you can make decisions to skip some of these.

This is a decision that can be more interesting than it first appears. If you are breezing through at 7min/mi pace, you probably don’t want to break it and stop for a refill. It is simply not economical. However, if you are running low on water, it is more difficult. You would never ever want to go without water for a mile or so, it is soul-crushingly terrible. In this case, you may want to ration the water intake until the next support station, or stop for a big refill now and try to make up the time by skipping the next two.

For an everyday runner, at mile 12 or 13, you probably would like to consider taking some food. Energy bars, jellies, gels, watermelon chunks, bananas, or M&M beans, all kinds. It is a great way to prepare for the wall. To be honest, I am not great at picking stuff out from my bag while running. As such, getting food out requires a brief stop. When is the most economical time to do so is not obvious. Uphills? Probably, it is definitely easier to stop and restart on uphills. But you also want to get food into the body before the glycogen depletion. Gels probably the fastest, it will take 5 minutes to kick in. Other solids can take longer. A mile or so before the depletion probably is required. Depending on these factors, there could be a range that we can take food more optimally during the race.

These decisions can be even more interesting if it is a self-supported multi-day event. Self-supported here means you carry your own food for these days (excluding water). Multi-day means a marathon a day. The decision is much more interesting because you are not just carrying a pack of energy gels. There are proper solids: pastas, ramens, instant rices, beef jerkys for your after-race celebrations. Simply put, energy gels for 6 days is not an option psychologically.

In this situation, the decisions on when to take what not only need to consider the optimality of the current race, but also the race next day. If the next day would be harder, I probably need to ration my energy gels today and have a bigger breakfast before today’s race to balance it out. It also cannot be completely rational. You would want to go with high energy-weight ratio food so that in the tougher day, the backpack would be lighter. However, you want to keep some celebratory food (beef jerkys anyone?) such that psychologically, there is a strong motivation to finish sooner. It quickly becomes an interesting game between the pace, stop-restart points, energy expenditures / refills and psychological reward functions. I simply don’t know an universal optimal strategy for this game yet with several trials-and-errors.

People say that life is a marathon, not a sprint. Well, I guess. As an everyday person, I would love to participate in the game with many more interleaving decisions and consequences. That is certainly much more interesting than the genetic lottery, isn’t it?