We recently published a study titled “Physiological Parameters Associated with 24 Hour Run Performance.” The paper is open access if anyone wants to read it. Just type the title into scholar.googel.com. One of the interesting things we observed in the data is that average running speed was highly correlated with fitness, but total mileage completed during the race was not. Taken in context with studies done by Guillaume Y Millet, it seems that if all other variables are held equal, the person that has the most cardio respiratory fitness will likely have the best performance in a race. Unfortunately, this is rarely the case except in a laboratory setting. In an actual race, several variables seem to act to limit or halt performance early. These variables likely include: Nutrition, susceptibility to injury, and psychological arousal. If for instance, you fail to take in enough salt, you could develop hyponatremia (too little sodium in your blood), which could end your race early. Or, if your leg joints were more unstable, you could develop a race ending injury. The thing which is interesting to me is about our study is the possibility that given enough data, we could predict an optimum race pace. I will attempt in the near future to publish our regression equation for anyone interested. It should be noted that this was developed for a hot, summer race, and the ideal pace may differ depending on environmental conditions. The idea of this is somewhat supported in the literature by the works of Martin D. Hoffman who has previously shown that minimizing changes in pace throughout a race is a strategy often associated with winning.
Now that we’ve covered the basics of fatigue during an ultramarathon, what do we do to reduce or minimize it? One of the key points I hope you picked up on is that a large portion of fatigue during an ultramarathon occurs because the brain reduces the amount of signal it sends to activate the working muscle. Therefore, the first thing I would focus on to reduce or minimize fatigue is to somehow boost that signal from the brain. How do we do this? Well, there’s several things we can do to boost the signal from the brain to activate more muscle: listening to music, having a pacer, sparing use of anti inflammatory drugs, and possibly alcohol consumption. All of these methods to some degree distract the brain from the perception of pain. When the brain senses pain from the working muscles, it may reduce running pace in an attempt to reduce the pain. Generally, anything which reduces boredom would also have a similar effect. The other effect we would want is to minimize inflammation. Diet and stress prior to the race would likely affect inflammation. If you are stressed out or eating poorly then you’ll have more inflammation going into the race. Conversely, if you maintain a high fiber intake with plenty of probiotics (yogurts) and you minimize life stress prior to the race then you would likely start with reduced inflammation. During the race, you can minimize inflammation by avoiding surges in your pace. However, eventually (6-8 hrs) your working muscles will produce inflammatory signals which can feedback to the brain and reduce the pace. A well timed dose of ibuprofen or 1 alcoholic beverage may reduce inflammation and restore pace for a few hours. The trick is want to time it right to avoid boosting your pace early on resulting in more inflammation. What I generally do is attempt to run the first 30-50 miles of a 100 mile race without anything to help me. No music, pacers, or pills. I immerse myself in the experience and focus on getting plenty of food and drinking appropriate amounts of fluid. Once I get past this initial phase, I switch on the music in 5-10 mile segments. I rarely have pacers, so this would likely alter my music use. I usually hold off on any anti-inflammatory drugs till at least the 100k mark. I wait later if I can still run. I take a very low dose ibuprofen. I would recommend consulting a physician before using any anti-inflammatory drugs since using these when dehydrated can result in kidney failure. The anti-inflammatory drugs will make me feel amazing for 10-15 mile bursts. I may end up taking a total of 2 doses. I should note that many people drink beer for the same purpose which can both suppress inflammation and provide a potent dose of energy. If you can make it within 5-10 miles of the finish line, the excitement of finishing will take over.
Before we can really discuss fatigue, we first need to have a basic definition to work from. Fatigue is generally defined as a temporary decline in the ability to produce force with the skeletal muscles. This can occur from either a disruption of the working muscles, or a decline in the ability to activate that muscle. Some of you may be wondering why I’m talking about force generation in an ultrarunning blog. It’s simple, the speed you are able to while running is dependent on your ability to generate force. In running, we see fatigue in a decline in running speed.
the reasons for fatigue vary depending on the length and type of activity. In a 5k, fatigue is usually the result of temporarily altering the environment within the muscle cell. When speed increases, higher threshold muscles (muscles which are more difficult to activate) get used which due to their untrained state will produce fatiguing byproducts. These byproducts then make it more difficult to activate the muscle and reduce force production / running speed. This could occur at any race distance if the runner did not pace themselves appropriately. During an ultramarathon, you might experience this running up a steep hill. Generally speaking, this form of fatigue is short in duration and may or may not impact your performance long term in say a 100 mile race. The disruption to the muscle cell can easily be corrected, if the pace is reduced. After running a steep uphill section, you may feel tired for a few minutes and bounce back.
Another cause of fatigue is depletion of carbohydrates stores, also known as glycogen depletion. This occurs when carbohydrate usage exceeds intake over a sufficient time period to use up the stored carbohydrate. Numerous strategies have been used to avoid glycogen depletion. The most common strategy is to carbohydrate load. The recommended way to carbohydrate load is to taper mileage 2-3 weeks prior to the race, and slightly increase carbohydrate intake. This has been shown to significantly increase carbohydrate stores. While this may extend the time to carbohydrate depletion, it will likely not be sufficient in and of itself to eliminate this aspect of fatigue from 100 mile run. In order to eliminate carbohydrate depletion as a cause of fatigue you need to focus on one of two strategies. Either increase the amount of carbohydrate you can consume during the race, or decrease the amount of carbohydrate used during the race. The first strategy means training your GI tract to tolerate large volumes of fluid carbohydrate during exercise. I generally recommend training with your planned nutrition the 2-4 weeks prior to your race. It may only take ~10 days to adjust, but it’s also beneficial to train yourself to eat to your plan. The second strategy, reducing carbohydrate usage is the subject of much debate these days. First, increasing your fitness will lower carbohydrate use by boosting fat use at submaximal paces. The second way is to go on a high fat low carb diet. The fuel you use during exercise is sensitive to the food you eat. Increasing fat intake and decreasing carb intake will make your body burn more fat. However, there is little evidence suggesting this actually improves race performance, and no evidence as to the long term health consequences of ingesting ~70% of your calories from fat. Some researchers decry high carb diets as leading to accumulation of arterial plaque, but at least there are several intermediate steps to forming plaque with a sugar. That’s enough to give me pause over whether I want a high fat approach. It should however be noted that some notable ultrarunners swear by high fat diets, notably Zach Bitter the 12 hour world record holder.
The last form of fatigue I would like to mention is somewhat speculative. We know from studies of people with chronic fatigue that the immune system can decrease the ability of the brain to activate muscle through inflammatory signalling molecules. I discussed this in my previous post on overtraining. Research has shown that during the course of an ultramarathon, the working muscles and immune cells produce significant amounts of the signalling molecules. The Millet lab has also shown that voluntary muscle activation decreases throughout a 24 hour race. While speculative, it is possible that some of the decline in pace seen throughout a 100 mile race could be due to increases in inflammatory signals. How could we combat this form of fatigue? One way would be to take an anti-inflammatory medicine such as ibuprofen or Tylenol (NSAIDs). These medications interfere with production of the inflammatory signals. The research over NSAIDs has clearly shown that a using these drugs early in the race or before to stave off inflammation is a bad idea. Probably what happens is they promote faster paces in the early part of the race which later results in more inflammation. What has not been tested is whether a low dose NSAID may be beneficial later in the race after pace has already declined. It should be noted that taking an NSAID late in the race could have dire consequences if the person were dehydrated or had reduced kidney function. Please use caution since people have gone to the hospital with kindey failure from taking NSAIDs late in the race. You should probably consult your doctor if you plan on doing this. Another option would be to use low dose alcohol or a nutritional supplement such as tumeric or resveratrol.
The last thing I’ll discuss is not actually fatigue, but muscle injury. While muscle injury is classically not thought to affect a single bout performance, the length of time of an ultramarathon is sufficient to allow inflammation from the injury and reduce the ability to activate the muscle. If your race includes a lot of elevation gain and loss, then consider adding downhill running bouts to your training as this can over time reduce the severity of the injury.
If you’ve picked up any running related literature in the last few years then you’ve probably heard of over training. What is over training? To be entirely honest, there is no clear definition of overtraining. Most sources agree that overtraining is a general fatigue brought on by training too intensely or too long without proper recovery. In other words, you feel like crap when you train too much. The problem with this general definition is that it doesn’t really explain the mechanism. Yes, increasing training volume and intensity add to the stress on the body, but when you get down to it, but the situation is more complex than that. Some signal in the body must relay this information to the brain. While it is still unclear how this works, some recent research with people suffering from chronic fatigue may hold the answer. To fully understand this you need to know something about how the immune system works. Most cells in the body, including muscle cells, produce signaling molecules. When muscle cells contract they will eventually produce a class of these molecules known as the interluekens, which are the cause of inflammation. If sufficient levels of these of these molecules get produced, they can feedback to the brain and decrease the motor drive in the brain. This results in the reduced pace often seen in over training.
So the question is, what can we do to correct this or delay it? The first thing is that over time, the muscles will likely become accustomed to the increased work load and produce less inflammatory markers. That may not help though in the short term. For the athlete looking to squeeze just a little more training out, I would recommend limiting other sources of inflammation. One of the largest sources of inflammation is the GI tract since it more directly interacts with environmental stressors from food. One of the easiest ways to reduce GI inflammation is increasing fiber consumption. Many of the bacteria vital to proper GI function feed on fiber, and increasing the good bacterial populations may reduce systemic inflammation. I think this may be why Scott Jurek had such a great effect when switching to vegetarian diet. Not only did he get a high dose of vitamins and minerals, but he probably optimized his GI bacterial populations. The second major thing is to supplement with live bacteria, or pro-biotics. I prefer kefir, but numerous forms of yogurts have healthy bacteria.
While somewhat speculative, moderate alcohol consumption (1 drink/day women; 2 drinks/day men) has also been shown to reduce inflammation. I suggest that maybe drinking moderately may reduce chances of overtraining, but this has not been tested in the literature.
One of the most daunting things about running an ultramarathon is combing through the blogs and magazines and finding that everyone seems to be running 100 miles per week. First, let me dispell that myth. Not everyone who runs ultramarathons is putting in 100 miles per week. I ran my first 24 hour race, although I only finished 12 hrs, on 25 miles a week. I did supplement with biking miles, but it can be done. I should note that I have never been more sore during and after a race. I myself max out somewhere around 60 miles per week. That still sounds like a lot, but you must realize that’s 1-2 weeks out of the training cycle. A friend of mine has won several races on 40ish miles per week. I say this not to discourage you from upping the mileage, but to point out that it can be done on less. More mileage tends to result in more fitness which can help you run a race faster.
Back to the main point, building mileage. How did I go, or how does anyone go from running 20ish miles a week to running 60+ without getting sick or injured? The coaching manuals out there tell us to limit increases to 10% per week to avoid injury. Based on my experience, it doesn’t matter what you limit your increases to if you have some sort of underlying problem. So the first thing I would recommend is finding someone to analyze your running gait, and check your arches. There are numerous athletic trainers out there who can do this. Particularly I would make sure they look at lateral knee motion, and arch movement. They can give you exercises to strengthen the stabilizing muscles which the majority of the time is the source of the injury. If you don’t want to go that route, find a good core strengthening routine that hits all the glutes and tiny hip muscles. This might be one possible reference
For arch problems, I would recommend find a good podiatrist. I discovered that my arch would collapse whenever I put weight on it. As a home remedy I used a rigid arch support. The orange insoles are my favorite because they have a little cushion. The greens are like running on concrete.
Another option is to look at shifting your stride away from an aggressive heel strike. Whenever the heel strikes in front of the body it places excessive force on the load bearing joints, muscles, and bone which can result in injury. This may require you to hire a coach, and frankly will require more writing in the future.
So the real secret to increasing your mileage is to minimize your risk of injury by first training the musculature, and if needed, to correct structural problems with orthotics.
The first time I heard about an ultramarathon was my senior year in college. I remember feeling a sense of awe for people that could run 50 miles continuously. It sounded crazy, ridiculous, absurd. Just the kind of thing I wanted to do, but I just couldn’t wrap my mind around the mileage I would surely need to run to finish such an event. If you read the accounts from ultramarathon legends you might well conclude that you would have to run 70-100 miles a week to stand any chance of completing such an event. So, I set out boost my running mileage and failed miserably. After a couple years of getting nowhere, I decided to sign up for a timed 24 hour race just to see what I could do. On 20-30 miles a week I gutted through the worst 12 hours I’ve ever had during a race, but I managed to run 52 miles around a 1 mile track. At the time my VO2max didnt even break 60 ml/kg/min which means I wasn’t in great shape. The fact is though, I made it. If I hadn’t just signed up and given it my all, I might never have become an ultrarunner. Over the last few years I’ve had a chance to test numerous ultrarunners in the lab, and I can tell you one thing, ultrarunners come in all shapes and sizes. Go to any race, and you won’t just find superhuman athletes. Sure there are some, but mostly they’re people who love running, the outdoors and are just crazy enough to push themselves through something extraordinary. I don’t mean to downplay the ultramarathon. Running 100 miles is the most difficult thing I’ve ever done, but the reasons it is difficult are maybe not what you would expect. Being in amazing shape I think helps, but in the end just getting through a race comes down to really 3 things. 1st, nutrition. Can you provide appropriate levels of energy, electrolytes and fluid . 2nd, psychological arousal. Can you avoid becoming so depressed/overwhelmed that you quit. 3rd, injury avoidance. Have you spent the necessary time minimizing your risk for injury. If you can address all three of these, then you should be able to complete 100 miles.