Why We Run: A Natural History - Bernd Heinrich (2002)

Chapter 18. Training for the Race

Running is the greatest metaphor for life, because you get out of it what you put into it.


It is natural for us to run, given the appropriate environmental stimuli, because during our evolution we acquired the genes that allow us to do so. I therefore have some faith that, given the right stimuli, most of us can become runners. We have the lungs, limbs, hearts, and minds for it, just as sandpipers have what it takes to migrate from North to South America. Of course, natural is not the same as good. Running well is for us now a value, not a necessity.

As Tanzania’s great marathon runner Juma Ikangaa has said, “The will to win means nothing without the will to prepare.” But how do you train yourself to do something so totally new as to run a distance that is twice what you’ve ever run before, when the distance you’ve run before felt close to your maximum? One thing I was sure of was that to train, as opposed to just run, I needed to have ideas of what I’m going to achieve and how I’ll do it. Any mistakes would be, as my experiments with honey, beer, and olive oil had shown, great lessons.

One of the beautiful things about running is that it is direct and elegant. The formula is simple: put one foot in front of the other. It doesn’t take much to figure out that if you want to improve sprint speed, you run faster. If you want to improve distance-running performance, you run farther. Although that’s all fine and good for getting in shape, it’s not good enough when you’re going for a win or a record. It is a given that the cheetah is already in superb physical shape, but the outcome of its race against an antelope, which is also in superb condition, can go either way, and it is decided by milliseconds of that indefinable something extra, or a blunder. The question is, how do you achieve that extra without any blunders?

As in Einstein’s formula E=mc2, I’d have to juggle a complex interrelationship involving energy, mass, and velocity. My sprint and cruising speeds were presumably fast enough to be a constant in the equation; I probably could not or need not alter them. The main alterable variable and limiting factor, I presumed, would be endurance, controlled by body temperature, fluid management, and ultimately by fuel supply in the muscles, blood, liver, digestive tract, and body fat deposits and by fuel mobilization. Clearly, there were two means to extend my fuel supplies. One was to supplement with carbohydrate ingestion during the run; the other was to train the fat-mobilization and fat-burning enzymes in order to tap into body fat reserves. In humans, available carbohydrate stores are thought to be sufficient to sustain maximum work output for 20 to 30 minutes, although fat stores can sustain a high work output for days. The problem for me would be that the rate of energy expenditure (and hence running velocity) generated by burning fat is only about 60 percent that available through carbohydrate. It is thought that high and continuous rates of aerobic work are best supported by mixed and simultaneous use of carbohydrate and fat.

To run to 62.2 miles would be to enter the body’s carbohydrate-fuel-depletion zone twice over. In humans, glycogen depletion spells exhaustion. To extend the tolerance zone, I trained to run on empty, forcing my body to get used to dipping into body fat as a running fuel after the muscle and liver glycogen reserves went low. I also wanted to use just as much carbo as my digestive tract would possibly process, to save those glycogen reserves for as long as possible before having to resort to fat metabolism, because carbo (sugar and glycogen) is high-octane fuel that provides greater power, and hence speed, than fat. As mentioned, sometimes I also practiced the opposite, running on a full stomach in order to be able to draw on that fuel. Runners competing at shorter distances, during which carbohydrate reserves suffice, need to train the digestive tract to shut off, as the body normally does with little inducement. Instead, I trained my gut to keep going, even as I ran.

Sometimes, to catch your antelope, you have to make compromises. The key to great ultramarathon performance is in setting goals and finding just the right balance between opposite and equally important necessities. Training must include intensely high mileage. Yet rest and recuperation are equally important. It takes rigid discipline to put in 10, 20, maybe 30 miles per day, with no excuses allowed, yet you need to be able to let up instantly when further effort might mean injury. Sometimes it’s necessary to pay immediate attention to the first hint of a blister or a slight muscle tear, while at other times you’ve got to be able to ignore pain for hours on end. Racing mentality requires a steady, unflappable calmness, and also a devil-may-care abandon where all the stops are pulled. Success requires uncompromising logic, and subservience to an overall goal that has, as life itself, no logical basis whatsoever. As Great Britain’s ultramarathon great Don Ritchie has said, “To run an ultramarathon, you need good training background, and a suitable mental attitude, i.e., you must be a little crazy.”

We live in a biological world of conflicting truths that together create the ever changing new out of the ageless. Our world is not a linear-logical construct that yields truths through ad infinitum extrapolation (except in physics?) by the use of scientific tools such as mathematics. That world, the one of unbending physical truths, exists in theory, but theory tends to be just an academic exercise when it has to compete with the reality of existence, or the real world of biology that we inhabit—the one that is both incredibly finely structured and chaotic. There is no precise formula that specifies how to prepare. There are only approximations, and best approximations, until something better comes along. Like infinity, the ultimate truth can be approached but never attained.

Should training involve running with a full, or empty stomach; going on short, fast, and frequent runs, or long, slow, and infrequent jogs—or some combination of both? What would best prepare me to achieve long and fast? At that time, in 1981, I knew of no ultramarathon training manuals. I did not know how others did it, and even if I had, how could I know whether their way was best for me? I was at my tar-paper shack in the Maine woods, training for the big race by running, felling spruce and fir trees with my ax, building a log cabin, and spending time in the field with bumblebees and an owl. I wanted my training to be as pure and elemental as my racing would be. No heart monitors strapped to my chest; I could gauge effort with my own body. No stretching and weight-lifting required. No fancy shoes with baubles and bubbles, nor stretch pants and synthetic warm-ups. No pills of any sort—not even an aspirin. My only concession to performance-enhancing chemistry was a good cup of morning coffee with plenty of sugar and condensed milk out of a can. No locked-in training plan, except to run consistently at a pace and distance that I felt I could handle reasonably. No rigid protocol. Only guidelines. Too much protocol can be suffocating and become an end in itself. Each day is special. Each day is different. I ended up running mostly at near-racing pace, usually speeding up at the end to hurry home to the hut and get the workout done, which served well to deplete my glycogen stores and allow the fat utilization to kick in.

The next most important consideration in running long distance is running efficiency—converting as much as possible of the expended energy into mileage. For a well-coordinated human to run a mile takes about 1,600 steps, at a cost of about 100 kilocalories for a man weighing 150 pounds. As much as possible, energy should be used to gain forward momentum while minimizing up-down movement. One’s feet, of course, necessarily involve an investment of up-and-down motion. But for a distance runner, that motion must be minimized in order to conserve energy. In a sprinter, energy economy per distance traveled is almost irrelevant, and knee lift and foot lift must be greatly enhanced in order to lengthen stride.

Lifting the feet a little with each stride, of course, cannot be avoided. It is just one of those costs that every runner has to pay. But animals have evolved to minimize cost. Birds minimize the lift work in their wing-limbs by having most of the muscles that move their wings on the chest, rather than on the limb itself. That way the limb stays light. Further energy is saved by having a very short humerus, and effectively achieving a very long but light forearm by having pinions that are as light as feathers, because that’s what they are. All the weight is concentrated as close as possible to the body. Swifts, the fastest endurance flyers in the bird world, have particularly short humerus bones and long, thin tapering wings. They are a particularly good example of the extreme of this principle. Similarly, such cursorial (running) animals as antelopes and ostriches minimize the weight of their lower legs, feet, and digits by reductions in number and in size. Toe amputation is not an acceptable option to most runners, but since I would have to take some 124,000 steps during the course of the race, I was quite mindful of the weight of my footwear. Lifting 1 ounce of extra foot weight 1 inch higher than necessary would, for my distance, be equivalent to lifting a 900-pound weight a distance of 1 foot.

The primary way to increase running efficiency would be to minimize leg lift while maximizing stride length, and of course, using the lightest shoes possible. I practiced running using gravity and momentum as much as possible to swing my feet. A sprinter expends exorbitant amounts of energy with each step, which is essentially a leap. I needed to train a stride that would be a compromise between an energy-efficient short step, where the feet are barely lifted, and a long stride, which necessitates more knee lift. By running as much as possible at race pace during training, I hoped to cultivate that specific optimum stride for the distance I intended to run.

What a long-distance runner can least afford to do is lift his whole body up and down on successive steps. He must glide. An ostrich or any other elite marathoner exhibits almost no up-and-down motion of the head or the shoulders. Suppose a 150-pound runner goes up-down only 3 inches with each step; then over the course of a 100-kilometer run he will have lifted his 150-pound body mass a distance of about 2 miles. That’s a lot of work, and it must be strenuously avoided in favor of horizontal motion.

Similarly, the energy of breathing must be minimized. In us bipedals there is supposedly a decoupling of the breathing cycle from the gait, and hence the energy expenditure from locomotion cannot be employed to also serve in ventilating the lungs. Contrary to this theory, at distance-cruising speed I coupled my arm as well as leg swings with my breaths. The number of arm and leg swings per breathing cycle and the depths of the breaths all depend on effort. But synchronization is maintained. The energy saved by such synchronization is undoubtedly very small, but it could add up in the long run. The goal is that eventually all of my body motions would be graceful, flawless, and executed without conscious will. Yet occasional editing of my form during training seemed helpful, especially when I was tiring on long-distance training runs, when coordination and running efficiency started to decline precipitously.

Training intensely would be important, but anything extrapolated to its logical conclusion leads to chaos, while anything not pursued with sufficient vigor is a waste of precious time. The Australian miler Herb Elliott claimed that his training routine under his coach, Percy Cerutti, would be considered “frightening” these days. That training was surely mostly speed work, for training the carbo metabolism needed for his specialty. I had once trained for speed myself, just barely managing to go under 2 minutes in the half mile. For me, it was a breakthrough, and it had been accomplished only after age thirty by repetitive speed work, mostly quarter and half miles, on the track. The key to ultrarunning success is obviously to run much slower, to spare carbo metabolism in order to last the distance. I’d never again have such sprint speed after training for distance. Nevertheless, I felt that training intensity was crucial, and for distance running that intensity would have to come from doing distance, not speed as such. Since I’d be running slower, the appropriately hard intensity could be achieved only by running to the fatigue point, and then to keep right on pushing, pushing, pushing some more: to run often in an exhausted state. By that time I endured it, because what had at first been a chore had become a ritual, and the ritual a habit. I did not have to think about it. I just did it.

As much as I believe that every twitch in my body has a physical cause and that what I do matters, there are times when imponderables rule. There were training days when I felt half dead. It was an effort to put one foot in front of the other. I slogged through the miles like a zombie, feeling aching tiredness through to the end. I wondered, Is it the pork chops I ate last night? Did I run too hard yesterday? Was it the peanut butter sandwich I ate just before leaving? There were other days when I felt light and buoyant, and I kept speeding up, feeling I could go on. On those days, instead of my perhaps intended 15 miles, I’d run 20 or 25. I wondered why I felt so good. It was always easy to rationalize. But the bottom line was, I simply didn’t know what imponderables were or are at work. I just hoped that I could identify some relevant factors, and that race day would be one of my lucky days.

When I started training in early May, I ran two or three 15-to-17-mile runs on successive days with the expectation of running the race on October 4. I was surprised to find myself getting weaker rather than stronger. That was frightening. Then I figured it out. I noticed that along with my fatigue came hunger, sometimes intense hunger. There were several times that I got so weak and hungry that I knocked at a stranger’s door, begging for a slice of dry bread. Once I was forced to stop and get a candy bar on credit at the village store only 3 miles from home, the cabin in the woods. The carbo worked wonders—I always made it home.

It became quite clear to me that in running distance, the big limitation was indeed fuel in the tank. I noticed that I gradually ran farther and farther with training. Why did I go farther before hitting the empty mark? My first hunch was that I was gradually training my body to burn some other fuel. That could only be body fat, although I could also have been packing more glycogen into the liver with each meal. My body would want to hang on to all the fat it could, but since it could not always indulge in its preferred carbohydrate fuel, it had to relent. The body would always use carbohydrate first, if it had any available. All of the carbohydrate stores in muscles and the liver are just barely sufficient in a highly trained middle-distance runner to finish a marathon. That would be just the start of the 100-kilometer, a frightening thought given that on some training runs where I went easy I felt exhausted already at near 20 miles. My second hunch relates to running efficiency. I was surprised that although I lost about 5 pounds of body weight fairly rapidly, I then soon stabilized my weight even though I ran about 20 miles per day. I never again got hungry during the run, and overall I was not eating much more than I normally did when I was not training. I was somehow getting incredibly more mileage out of the same number of calories. I suspect, therefore, that my running mechanics and possibly the cellular metabolism were becoming more efficient. That is, more energy was being converted to mechanical power and less ending up as heat.

They say that in racing one is really competing against oneself. For me, the race began in May, and until October 4 I would run it all by myself, against myself. In the meantime, I collected mileage. I could not run my racing distance on any one day, but by running often or long in a depleted state I simulated race conditions. Surgery on a broken medial meniscus cartilage of the left knee (due to injury sustained while chopping trees for the log cabin I was building) on May 19 initially slowed me down, and indeed at first almost crushed my dream. Then it made me more determined than ever. After a couple of weeks I increased my mileage again and by late summer I averaged 20 miles per day, generally alternating daily between longer and shorter runs. I regularly did a 30-mile run on the weekend, and except for two weeks around the aforementioned operation, I took not a single day off. I consistently ran over 120 miles and often up to 140 miles per week.

As Frank Shorter has noted, “There’s a certain aspect of any athlete’s mentality, which is to not waste an effort.” Since saving time is important in my schedule, I had to rationalize to myself, and especially to others, why I could spend two, sometimes even three, hours per day, for up to three months, just running down roads. My excuse is less that I can think and reflect on long, quiet runs than the realization that others are capable of just chatting or reading the newspaper for nearly as long, and thinking it time well spent. As for loss of my scientific productivity, the time of preparation for the race might add up to what is needed to produce one small research publication that only a half dozen people would likely ever read, if it’s experimental science. Anyone who is able to justify the second can surely justify the first, and vice versa. And I decided that I could.

In late August, when we came out of the woods and returned to Burlington to teach at the University of Vermont, I still did long runs, usually to and from work. Also, I now sometimes ran at noon, or put in a short run before or after the daily long run. I wanted to make my body think it had to run all the time. I never walked. Even if I needed to go only 50 yards to the library or to my car, I jogged. My body must not be allowed to think it could ever walk again. Running had to become the natural mode of locomotion, and it became such.

The motions of a trained athlete are automatic. He doesn’t have to think about most of them, unless trying to ferret out flaws. I sometimes went to sleep at night trying to consciously visualize my stride so that I felt like I was feeling the poetry of motion, without the added pain. It made me feel good, as if I were a spectator and a critic. Even the tiniest inefficiencies of movement can make a huge difference over a long distance. I often noticed that muscle tenseness could be relaxed by conscious effort. I then focused attention on my calves, thighs, arms, trying to relax them even during training runs, so that only the most essential running muscles would be exercised. For a mile or so I would monitor and hence try to control the kick of my arm swings, to make sure no energy was wasted in side-to-side motion.

By mid-September I was getting close. This was really going to happen! On September 15, after a long, exhausting run the previous day, I did four short, easy runs of 2, 7, 2, and 2 miles. The next day I ran 2 miles, 20 miles (in 2:00), and then another 2 miles. The next day, 2, 10, and another 2 miles. And the next day 2, 40 miles (in 4:39), and then 2 more miles in the evening. I wrote in my training log that I ran the first 20-mile loop of the forty in 2:19, and that I was “about to hit the wall but then gulped three cartons of juice, and picked up again…finished fairly strong. Feel confident I could have gone much farther and faster, if I’d had two juices every 5 miles.”

On September 19 I relaxed and did only 10 miles, and noted that “legs feel fine.” I was on track. The next day I ran 2 miles, then a regular 7-mile loop, but fast, for a time of 41:13, which broke my previous training record for that loop by 16 seconds. My log says: “Felt slow at first and strong at end. Could have gone on for much farther at same pace.” The following day, even though it was raining and windy, I did my 20-mile loop in 1:58:30, also a new course training record. It was not all out. I usually tried to keep a little back, so that willpower would accumulate, like a battery on charge.

I did not have the benefit of hindsight that the recent work on the physiology of migrating birds now provides. However, I did have an inkling that intense training for an ultramarathon has some similarities to a bird’s intercontinental migrations. Birds migrate to their ultimate goal in stages, which are like ultramarathon workouts. Even as they exercise, their work capacity drops steadily as body tissues—including wing muscle and heart—are burned up for fuel. Curiously the resting metabolic rate of their remaining body tissues drops a whopping 45 percent. I did not know this at the time, but I still felt that training hard for too long would be counter productive, if not damaging to the body. I tried to peak for a specific race, much like birds physiologically prepare for each specific ultramarathon flight.

Three days later (no days off), I entered a 10-mile tune-up race in nearby Essex Junction, Vermont, not to race but to get a feel for my pace under race conditions. I did not record my finishing place (I think I was third), but I listed my time as 54:03 in the running log. The next day I took it easy, doing only 7 miles, and the following day I set a new record (by 5 minutes) on my 20-mile course, a 1:53:30, for a 5:40 per mile pace, and I wrote, “Felt strong at end. Not exhausted. Could probably have carried this pace for 15–20 more miles. Did not stop to drink.” I was recovering quickly, as is necessary for running long and hard. Only six more days until Chicago, when I could let loose and it would all be over.

In just a short period of time, relative to what a lifelong endurance predator would have experienced, there was no longer any doubt that I could do what was unthinkable before. I could run farther, faster, and at longer intervals than I ever imagined, and if I could do it, so could almost any other healthy adult. We are all runners, if we have to be or seriously want to be. I knew I could handle the previously unthinkable exertion of running the entire 100 kilometers. The only relevant question was, at what pace?

The point of training is to condition the body to handle exertion. At some point exercise becomes a stress, physically, psychologically, and hormonally. Much has been written in the scientific literature about stress. It is thought not to be healthy for you and that you should avoid it. I wasn’t worried. Stress is the expenditure of energy. You can’t live without it. Some think that you are given a specific number of heartbeats per lifetime, and they would rather not use up their quota by running down a road. Although running at less than maximum speed may increase the heart rate up to 120 to 140 beats per minute from a “normal” 60 beats per minute, after a few months of training, the resting heart rate for the other twenty-three hours of the day may greatly decrease. (Mine went down to 34 per minute.) That is, at a daily cost of 4,000 heartbeats during an hour of exercise, the athlete may save nearly 36,000 heartbeats a day, for a net saving of 32,000 beats a day out of 86,000 used otherwise, assuming the stress of running is balanced with the rest needed to allow the benefits of stress to be realized.

I heard other arguments against running. One colleague who was worried about my longevity (or sanity?) sent me a research publication showing that running exercise induces the release of the stress hormone cortisone, which other studies had implicated in causing brain damage and other degenerative conditions. The researchers concluded that, therefore, chronic running would induce loss of neurons and cause premature aging. I wasn’t particularly worried. As is usual, there are usually other effects as well. In another study, BarryL. Jacobs and colleagues from the neuroscience program at Princeton University showed that when mice ran every day on an exercise wheel, they developed more brain cells and they learned faster than sedentary controls. I believe in mice.

What most researchers failed to consider was the variable of time. Running is stressful only to a person who is unaccustomed to the exertion. But with training, running becomes normal. I had decided to run so much that normal running would no longer be a stress, only fast or long running. I could now run 20 miles every day and it felt quite normal to me. The important thing was that I had worked up to it gradually. Time and timing is everything. There is a world of difference between immediate effects and ultimate consequences. During training, it was less important to avoid running stress than to avoid other stresses, like those I had experienced as a student. If stress indeed causes loss of neurons, if not also brain damage, then I sustained a lot more brain damage while I was a student than when I was a runner.

I also believe in antelopes. They would not have missed a trick when it comes to running speed and endurance. I had never seen or heard of an antelope who was flexible and did stretching, or who lifted weights for extra strength. I had never heard of one doing much more than eating and running. However, if I had read modern exercise literature, such as the recent excellent book by McArdle, Katch, and Katch, or The Lore of Running by Tim Noakes, I might have done not only stretching, speed training, and weight lifting, but also warm-ups and cooldowns. I had, of course, heard rationalizations for all of these procedures, but I didn’t know if I was hearing facts or folklore. I suspected that the most highly motivated and the best runners would try almost anything no matter how bizarre, if it was recommended for improvement on the basis of some rationale. If, for example, a world record holder always took some herb on the basis of some pseudoscientific hunch, then others would copy him and soon advertisers would crow about the product, attributing power to it, and thus, with potentially no evidence whatsoever, folklore would substitute for fact. I didn’t know of any convincing set of data that proves, for a runner who puts in 10 or 20 miles per day, the specific increment of improvement that would result from a given number of stretches or power lifts. I’d never heard of a yogi who was a great runner. It seemed to me that muscles are like rubber bands—they produce power only after being pulled taut. If long and lax, they have to contract “for nothing” until they become taut. I never stretched.

As for running causing premature aging, I also know of no objective studies that go beyond rationalizations to provide proof. As to rationalizations, my own was that since many animal studies, from mice to monkeys, show that reduction of caloric (food) intake increases health and longevity, then maybe the relevant variable is caloric deficit, and so exercise, by reducing caloric excess, should do the same as food reduction.

It is very difficult to factor out the many lifestyle variables that are correlated with people who run as opposed to those who don’t. For sheer longevity, it is hard to beat Carlton Mendell, a competitive runner since high school and a former member of the Maine Senate and the Maine Rowdies running club. At age sixty-two Carlton covered 125.5 miles on the Bowdoin College track to set the U.S. age-group record. By 1999, at age seventy-eight, he had run 126 marathons, and had no plans yet to shy away from running—not even ultramarathons. I’m not sure if his continuing vigor is due to his running or in spite of it. I suspect it is a little of both. He is an experiment of one. And so, with respect to training, am I. The results of that experiment were about to be revealed.