Friday, February 28, 2014
Pre-run nutrition really matters (?)
I had gotten into the habit of eating something before my runs, like a banana or a piece of toast with peanut butter or some yogurt, about an hour before I start. And that pretty much was ok - no issues.
But not too long ago I had a conversation with a fellow Marine Corps Marathoner, who happened to be a doctor, and his opinion was that pre-run fueling like mine was unnecessary. He stated that the food that I might eat an hour before running simply does not have time to run through the digestive process in order to really affect my body, with the sugar content being the only exception. The sugars in the carbohydrate content get processed very fast (in fact any sucrose, glucose, matodextrin or maltose) to produce glycogen, the fuel needed to make muscles work. But this is typically short term fuel, i.e. it won't last me long...
I argued that my "eat something an hour before" practice seemed to work, to which he replied that this was simply because my body's metabolism had become accustomed to sucking the sugars out, but then also suggested that I probably felt the need to refuel by mile 4 or 5... which is true.
So after the MCM I tried to get into the habit of not eating prior to a run. Since I run first thing in the morning, I would just have a cup of coffee (ok, maybe two cups) and then out the door. And that seemed to be ok. Granted, my recent runs have been less than 10 miles, lots of 3's and 4's, with 5's, 6's, and 8's scattered in there. For my longer runs, I would suck down a GU around mile 5 or 6 to get me home (he also had an opinion about that, but that's a separate topic).
But today I had a really odd experience:
I'm up early, but got involved in various tasks and did not get out to my run until almost 3 hours after my intended time (bummer). Feeling that I might need some fuel since I had delayed my departure so much, I munched down a banana and a small piece of whole wheat bread with some peanut butter (I felt hungry...), and about 20 minutes later I was running with a 5 mile run planned.
At Mile 2 I felt the beginnings of what I call "fuel fatigue", that feeling that I'm lacking fuel and I'm running out of gas. By Mile 2.5 I felt like I was going to bonk (so weird!!), so I sucked down a GU and ran on. A quarter of a mile later, I had to walk. I felt like I had nothing in the tank. Bonk.
As I walked my mind is scrambling to figure out what was wrong. By this time it had been an hour since I had the banana, and about 45 minutes since I had the bread (albeit small piece) and peanut butter. I realized that the GU would take a few minutes to take effect, but why the hell hadn't the banana and peanut butter kicked in??!!!
About 10 minutes after I sucked down the GU I felt recharged enough to run again. In fact, without even thinking about it, I posted a very nice 4th and 5th mile times.
I owe the last two miles to the GU - I am sure that stuff is the only reason that I was able to run well. But conversely, I don't like the fact that it worked - it is such a crutch. Perhaps it signals an issue with my body's inability to store and manage glycogen. Or a lack of preparation on my part for the run...? I finally realized that by the time I started my run it had been 16 hours since my last real meal, and the banana and peanut butter were tea-spoons of fuel too close to my run start.
I'm going to pin my mid-run bonking issue on the period of time since my last real meal (16 hours) and the fact that the banana and peanut butter had nothing to work on and were unable to be digested into usable energy.
Interesting stuff - time for a better plan...