anyone NOT hit the wall during marathon? (Read 3814 times)

You always here its going to happen...has it ever not happened?

I was fine during the marathon but hit it hard during one of my 20 mile runs, at about mile 18...it was like I just couldnt make myself move or like I had to think of putting one foot in front of the other, it became that bad. I explained to my friend what happened and he said you call that the wall...and asked if I had drank enough...which guilty I did not...so I made sure from then on to have plenty of stuff with me to drink and with the exception of the first water stop in the marathon, I stopped at every one of them and drank both water and gatoraid, and had some GU...never saw the wall...at least that one anyway

Around mile 24, the soreness I had been feeling went from tolorable to bad crampping in my legs.

I can say I did start out too fast but did it on purpose so I'd be able to easily beat the cut off time/bridge

had about 3 GU gels on top of all the water and gatoraid

If I've hit it, I only did it in my first marathon at mile 24. I felt like I had to stop and walk. I was able to suck it up, though and run it on in. I felt like a drunk at the end, though, paranoid that the police were going to toss me in a squad car. Now, I did that marathon off Higdon's novice program and ran faster than I expected.

Other than that, I think I'm genetically predisposed not to hit the wall. I may not be a speed demon, but I seem to be able to churn out miles.

I have ran two and did not hit the wall with either. I think for some they ran too fast, or they did not run enough in training. Your legs are suppose to be tired the last 10K. For me if I walked once in that stretch I'd be doing the run/walk from there to finish.

I hit the wall on a bike ride where I had an unplanned 80 mile bike ride with only one bottle of water in the heat of the day. I was tired, but fine, then at the drop of a dime my legs locked up, and could do nothing but walk my bike, luckily only 2 miles to home. I'm pretty sure the wall is way past 20 miles for me.

Given how crappy my training was for my first marathon (my longest run was 16.6 miles ran three different times) I'm surprised I never hit the wall. When I finished, I felt like I could have gone again except for the pain from my blister and the slight swelling in my right lower leg which later swelled to look like a small baseball sitting there (it was gone within 36 hours of finishing).

I knew that my training was sub-par going in so I went in with the attitude that no matter what I run it will be a PR since I've never run this distance. I also decided in the weeks leading up to the marathon that I really wanted to enjoy the journey and take in the sights around me which kept me from running too hard the whole time. Thanks to that mindset, I had a total blast!

MTA: I drank at least one cup if not two cups of water at EVERY water station and in between I drank at least 6 8oz bottles of water I was carrying (I had two that I refilled twice) plus drinks of Gatorade after every water station and one gel every 4 miles or so.

Heh, I also decided I'd get a PR no matter when I finished because it was my first (last weekend) -- as long as I lasted past the 18 mile mark, I'd get both a marathon PR (even if it was an incomplete, it'd be my furthest incomplete) and also a longest-distance personal best.

I didn't hit the wall. I got tired of how sore my feet and legs felt around mile 22, so I decided to quit the walking breaks and run straight in, and start going faster -- I figured, my past experience was exclusively 5Ks, so heck, let me run the last bit in like a short distance runner, so I accelerated all the way to the end -- well, I was starting from quite a slow pace, so getting up to about 8min/mile at the end felt pretty fast to me by comparison.

Fuel for the Run, Fuel for the Race

Running is one of the most efficient ways to burn stored calories. As we begin to ramp up through marathon training season, let’s consider how your body stores and uses calories to fuel your runs, and what the limits are for using these energy stores. In this discussion, I will use the abbreviation kCal to represent calories. When you look at the nutrition information on your food, the calories it reports are actually kilocalories (i.e., 1000 calories), but it is simplified for consumers. In this discussion, I will use the more accurate kCal.

I will also refer to percentages of your “maximum effort”. Your maximum effort is about the effort required to achieve your maximal heart rate or to calculate your VO2Max. This is about the same effort you would use to run your fastest 200-400 meter interval run following an adequate warm up.

This discussion does not account for hydration, caffeine or electrolytes, as they are independent topics that merit their own consideration.

Energy Sources

Your body uses two energy stores to fuel the run: glycogen and fat. Glycogen is your body’s form of stored carbohydrates, sugars and starches. Glycogen is the primary energy source used for fight or flight type activities, which means it is the primary energy source used when running hard. When you run above 80-90% of your maximum effort, your body is burning almost entirely glycogen to fuel the effort. Below that, your body starts using the second energy source, which is fat. An inaccurate but useful rule of thumb is that your body fuels its effort using glycogen as a percentage of total calories used that is equivalent to your percent effort. So if you are running at a 70% effort, about 70% of the kCal you are using to fuel the effort are coming from glycogen, and the rest come from fat. Running on fat stores works very well, but fat burning is less efficient than glycogen burning, so you have to run more slowly.

The human body can contain a maximum of about 2000 kCal of stored glycogen. Glycogen is the energy source we use when we run. Your body stores glycogen in the muscles and in the liver. Most of us burn about 100-140 calories for every mile we run, which means that when running hard, we will run out of glycogen after about 16-18 miles if you start out with full glycogen stores. After you run out of glycogen, your body will force you to stop as you transition from burning glycogen to burning protein (i.e., your leg muscles). Once your body has transitioned, you can run again, albeit more slowly. This transition can be very difficult or painful, and is often referred to as “bonking” or “hitting the wall”.

While your body can hold a maximum of about 2000 kCal of energy stored as glycogen, it holds another 4000 kCal for EVERY pound of fat you have (e.g., a 150 lb person with just a 5% body fat will still have almost 8 lbs of fat, worth about 32 000 kCal). Energy expenditure while running is a function of your weight, and to a lesser extent the grade of the road, and to a far lesser extent to your pace. So an 8 minute per mile runner burns energy at about the same rate PER MILE WHILE RUNNING as a 12 minute per mile runner who has the same weight. A 150 lb runner will burn approximately 120 kCal per mile run.

Your Energy Limits

As above, the reason you bonk in a run is that you run out of glycogen. If you weigh 150 lbs and are running above 80% effort, you will use about 2000 kCal worth of glycogen in about 21 miles. If you are running at a 70% effort, it will take you 24 miles to use 2000 kCal worth of glycogen. So why do you bonk at mile 16 or 18? Well, even if you carb load absolutely perfectly (and most of us do not), when you finish loading, you then go to bed and sleep. When you wake up marathon morning, your body has used up as much as 25-30% of your glycogen just keeping you alive overnight. And the next morning, the little bit you are able to force down into your stomach, well it does not ever get a chance to be stored as glycogen. Go out too fast and you will burn predominantly glycogen relative to fat and use up your stores more quickly.

In general, the more you run in your life, the more efficient you get at burning glycogen at a given pace. This is based on total lifetime miles, total weekly miles and total quality miles. People who have run distance for years, and who put in 40-60+ miles per week use and replace glycogen more efficiently than folks who have only been running for a short time and who can only put in 20-30 miles per week or less. The more efficiently you burn glycogen, the less quickly you use it up, and the further you can go at a given speed and effort. Your genetic makeup may also play a role in your glycogen efficiency.

Extending your Fuel

Taking in calories during the run can extend this by preserving some of the glycogen that is stored in your liver. A packet of energy gel has about 100 calories (worth just under a mile of running) and a 4 ounce cup of a standard sports drink has about 8 calories (about 50-100 yards). Of course, you may actually get fewer calories than this if you don’t consume the entire gel packet or your sports drink is mixed to a dilute concentration.

When you run hard and approach your maximum possible effort, your body cannot digest well. This is primarily because your blood is pumped away from your gut and to your muscles. In this situation, even energy gels can be hard to digest. At a true 5k effort of ~90% of your maximal effort, you should have trouble digesting even water or sports drinks. At a true marathon effort of ~70-80% of your maximum effort, you should be able to tolerate candies, simple carbohydrates and fluids, although you may have more trouble with some than with others. At an ultramarathon effort or a walk, you should be able to tolerate and may even crave more complex foods such as candy, potatoes, PB&J, soft drinks, etc. All of this requires trial and error. There is also a limitation to how quickly your body can absorb the calories that you consume. I understand that the ceiling is about 3-400 kCal per hour during exercise, while most of us burn 5-800 kCal per hour depending on weight, pace and ambient temperature.

If you feel you need energy supplementation on training runs, you should be able to take in any simple carbohydrate source. Energy gels are good if you want something portable. I personally prefer Little Debbie Oatmeal Pies or Star Crunch bars. I will also occasionally have a nut/granola bar, a banana or banana bread. I usually only have these during the run if I am running over 14ish miles, although I often run miles easy with no calories on the run other than a few cups of sports drink (~<50 kCals worth total). If you are bonking on your marathon training runs, you may be running them too hard and/or you are not taking in enough calories in your daily life.

When to start supplementing your stores by consuming energy sources on course is really a matter of personal style and experience. The manufacturers of these products always recommend that you take some before exertion and then every 30-45 minutes during ongoing exertion. Of course, they are selling a product and want to sell more. Many marathons offer energy gels around midway and in the last quarter of the race. If you carry your own, you can take them when it is convenient to you, and you can always grab several packets during the race and save them for later. I usually try to space mine regularly rather than wait until my energy is waning, but others wait until they need that extra boost in the final miles. Try it in training and on your long runs and find out what works best for you.

An Example

Playing with the math, we find the following. Assuming that you weigh 150 lbs (thereby burning 120 kCal per mile), that you are running your marathon at 75% effort, and that you are able to store 2000 kCal, but that you also slept during the night and burned 25% of those calories, but that you take enough energy gel and sports drink to get 2 extra miles:

((2 000 kCal glycogen * (1 - 0.25 burned last night)) / (120 kCal per mile * .75 effort)) + 2 miles from carbs on the course = 18.6 miles

You will bonk at mile 18.6. Or so. It is never quite this predictable. You can also attenuate this by long-term training (which increases your total body glycogen storage abilities and improves your fat burning at high exertion over time).

Pithy Quote

Tim Noakes, an internationally renowned running physiologist, described the body’s limits well in his, The Lore of Running. Among many other things, he writes:

"The marathon is less a physical event than a spiritual encounter. In infinite wisdom, God built into us a 32 km racing limit, a limit imposed by inadequate sources of the marathoner's prime racing fuel -- carbohydrates. But we, in our infinite wisdom, decreed that the standard marathon be raced over 42 km...So it is in that physical no-man's-land, which begins after the 32 km mark, that is the irresistible appeal of the marathon lies. It is at this stage, as the limits to human running endurance are approached, that the marathon ceases to be a physical event...It is there that you learn something about yourself and your view of life." (Noakes, The Lore of Running, p596)

Putting it Together

So, how do you use this information to ensure that you avoid running out of stored energy during your goal race? There are several things to keep in mind, based on what I have just presented. These include:

1. Know your pace ability and run it – running too hard for your body’s abilities and training level will favor glycogen burning, and can cause you to use your stores too quickly. Your abilities relate to your race specific training and your innate potential, and they manifest in how your body handles its energy stores as you run. You can determine your pace ability by running shorter races during the same training cycle and extrapolating from them; e.g., do not start your marathon at your recent 10k pace.

2. Start your race with a full tank - make sure that you eat adequately in the days leading up to your goal race, favoring carbohydrate rich foods and consuming approximately 125-150% of your normal baseline daily intake. In the final 12 hours before your race, eat several easily digested small meals made up of simple carbohydrates and fats.

3. Know your in-race fueling strategy – make sure that if you plan to take in calories while running your race, you have experimented with this process and know what works for you. If you prefer a specific energy gel, carry it with you or select a race that offers it.

4. Loose weight - the less you weigh, the more slowly you will burn your stored glycogen and the longer you will be able to run before transitioning to a fat-burning pace. If you have weight to loose, work on loosing it, especially before your training cycle begins.

5. Expect the unexpected – even if you do everything correctly, run in your abilities and have taken in adequate nutrition, you may still crash. This could be due to unexpected climatic conditions that divert some of your energy stores to handle, such as cold or wind or rain or big hills. You will need a backup plan, which may include slowing your pace, changing your race goals, increasing your on-course calorie consumption or even dropping from the race and refocusing on another.

trent-

 

great post (2 years later). but, thanks! i've been worrying about this as much as everything else. very informative. i've noted some training programs advocate not taking gels during long runs to get the body used to running low on glycogen. i did that during training for my 1st marathon (only taking gatorade later on in long runs). it didn't work for me during the race. and, there was also a 20 deg temp drop over the duration (race in late oct on cape cod), sleet. literally shivering by mile 19- didn't have the fuel left even to stay warm. so, last 10k a horrible slog (uphill to add insult); vowed i'd never do another. hope that doesn't happen this time (many years later, different course). i am practicing taking gels every 5 miles now for lr's 15 and over, and sports drink every other stop in practice events. also hoping to get in more than 20 mile training runs before the marathon (i really believed this was a problem for me last time). thanks again, tho, for your insights!