Diesel fuel or High Octane Fuel for the Boston Marathon

I'm about to show my lack of medical knowledge, but hang with me while I draw some basic analogies that I firmly believe to be true. It will help you understand what a long run does for you, what the purposes are for the various types of long runs.

First off, the medical folks tell us (and I have no reason to disbelieve them) that long runs encourage and facilitate the creation of additional and new capillaries for delivering more blood to the leg muscles. This gets more fuel and oxygen to where it's needed. It also explains why, as the long runs grow longer, that they don't really get all that much harder -- your body is adapting to them. However, this bit of trivia doesn't really help you, since it will occur whether you know and understand it or not. Pretty much all of your long runs give you this benefit.

When running, you have two sources of fuel available. The first is fat (#6 diesel fuel), and we all have more than enough (since one pound of fat provides enough calories to power one for about 30 miles and very few of us are less than 8% fat -- you can do the math for your selves). The other is glycogen (high octane jet fuel) that is already in the blood stream from carbohydrates (sugar, whether simple or complex -- simple sugars simply get there faster and hang around for a shorter period of time -- complex ones take longer to get there and then hang around for longer once there -- thus, don't be afraid to take in simple sugars during the race itself).

When walking or running slow, the body is content to burn mostly fat; or at least a mixture of fat and glycogen. When running fast, the body aggressively seeks out the hotter burning fuel (the high octane jet fuel glycogen) and tries to bypass the fat. When the glycogen is depleted from the blood stream, then you're left with just fat as a fuel source. This condition is known by many names -- "the wall", "bonking", etc.

All fuels, but glycogen in particular, require a great deal of water in order to work. Fuel without water equals dehydration. Not good.

For simplicity's sake, I'm going to make some assumptions. Let's just assume that when running, we're in one of three states: 1) 50/50 mixture of burning both fat and glycogen, 2) a hot burn of glycogen only, and 3) bonked and burning fat only. In reality, it's a bit more complicated than that, but I think you get the picture.

So, when do these three situations occur? Which ones do we want? When do we want them? How can we control when they occur? How can train and run so to teach our bodies to burn the fuel in the way we want it to?

First off, the obvious goal is to not bonk in a race. Not fun. Since very few of can reliably stock up enough glycogen to last an entire marathon, burring glycogen only isn't a very good strategy. Most of us burn around 120 calories a mile, and if we carbo load to perfection, we might get in around 2000 calories. Do the math -- you don't make it to mile 26. You can, of course, take in calories during the marathon (and you should). However, remember that calorie intake during the run (or race) MUST be accompanied by large amounts of water. Otherwise, something far worse than bonking will occur. Your first clue will normally be nausea, followed perhaps by white salt streaks on your face and clothes. It's called dehydration. Not good.

On the other hand, burning fat only (which is being bonked) is usually not pleasant and is unlikely to lead to that coveted marathon PR. Therefore, the obvious goal is to burn a mixture of fat and glycogen for as long as possible. There are two key aspects to this. One is race strategy, and the other comes from the long runs in training.

Regarding race strategy: For the marathon, don't go out too fast. Going out too fast inspires your body to quickly go to an all glycogen burn. It'll feel good for awhile -- in fact, around miles 8-15 you'll probably feel great -- fully warmed up, cruising, and burning the hottest fuel you've got. But, somewhere in the mile 17-22 range, it's unlikely that you'll have been able to eat and drink enough to hold off the infamous wall. It'll be ugly. As long as you avoid dehydration, you'll live, but at the time you may find the merits of living to be debatable.

You can probably only fool your body into remaining in the 50/50 burn for about 8-10 miles (and only then if you go out slowly, ease into your goal marathon race pace over the next 2-4 miles, and have done the long run training described below). At that point (miles 8-10), in order to maintain the race pace, you're probably going to convert over to a full glycogen burn (remember me saying that miles 8-15 are likely to be sweet?). What this means is that around mile 10, you need to start taking in the gels. Taking them before that (such as pre-race or in the early miles) simply causes an insulin spike that will trigger your body to go a premature glycogen burn, will bring the wall closer, and will create the need for even more water intake (because you're not going to have to eat even more). Port-a-pot stops don't help the PR objective either, but I wouldn't worry too much about that aspect. According to this logic, a second gel would then be in order around mile 17 or so, providing that you can take in enough water with it. Ditto for around mile 22. Otherwise, the best advice is to suck down as much sports drinks as possible at every opportunity during the entire race.

On the other hand, it the race is not a marathon, but something short -- say a half marathon or shorter -- then taking fuel (such as a gel) about a half an hour before the race is a good idea. In the short race, you're not worried about hitting the wall, and you WANT to go to a glycogen burn as soon as possible. Take the insulin spike, do a warm up mile or 2, hit it hard from the gun (that is, go to target race pace right away), and burn the hottest fuel you can. But, for the marathon, eat a lot the 3 days before, with your last major meal around 4:00 PM the day before, take in a lot of fluids the night before (sports drink is good), eat whatever your breakfast is at least 2 hours before the marathon, and then just stay fully hydrated until gun time. Drink a lot of water and sports drink for the first 10 miles of the race, and then take a gel with a lot of water. Continue to drink sports drink until the next gel, and so on. Never stop drinking until you're past mile marker 25.

Now, to the important part. What does all of this mean for our long runs in training? The first and most important objective here (other than the endurance and aforementioned capillary development that one gets from long runs) is to teach our bodies to stay in that 50/50 mode for as long as possible. The way this is done is to do long runs where we eat the day before, but not the morning of. Take in minimal or no food the morning of the long run. Black tea or coffee is fine. Before, during and for 1-1/2 hours after the long run, take in water only. The exception to this is during hot water, when some electrolyte replacement is needed (either from supplements or by taking in some sports drink -- my own method here is to use a dilute 50/50 mixture of sports drink when temperature are above 70 F). Then, after the 1-1/2 hours, eat brunch. These runs can be as long as 22 miles and MUST be slow (slower than 9 minute pace). In general, 3 out of 4 long runs will be of this type. For runs of this type over 2-1/2 hours, one will often indeed go "through the wall". However, due to the slow paces, it will be a very gentle crash, and will simply feel more like one is getting very tired. Not painful at all. That's why many slow marathoners claim to have never experienced the wall.

Another objective of the long run is to learn to run at race pace when tired, and to get practice in taking in fuel during the run. These long runs will have a speed aspect to it -- such as fitting in a local 5K-10K race in the middle of it, doing a 5x1 mile repeat workout in the middle, or by doing the last 7 miles of the run at marathon race pace. These runs are fueled much the way you would on marathon race day -- carbo heavy dinner early the day before, plenty of fluids (not alcohol) the night before, no carbs closer than 3 hours before race time, and staying hydrated (water) right up to the starting line. And, should you eat right after these types of long runs (especially easy to digest protein). This type of long run is only about 1 out of every 4, and will require a bit more post run recovery than the other type. Doing a (fueled) long run where you, for example, run easy for 6-8 miles, then go hard in a local 5-10K race (and go to full glycogen burn), and then run 5-7 mile easy cool down (while drinking and fueling) will simulate race conditions but without the wear and tear and injury risk of the actual marathon -- you should be able to recover easily for upcoming midweek speed session. For the fat burn long runs, one easy day afterwards, and you should be ready to go back at it -- recovery should be very quick (which is another goal of a long run -- it has to be something you can recover from, so as to not interfere with the rest of your training plan).

Following the above with a ramping up pattern for the long run distance (with step back recovery weeks about once a month), getting in a 6-8 week phase where you hammer some 800's, spacing out the runs with slower/shorter recovery runs in-between the hard days, a good taper -- geez, I've just about told you all of my secrets .... all good stuff to talk about on the next long run .....

Steve