Endurance Training

By: Nick Soleyn, BLOC Staff Coach and Editor in Chief

Endurance

More than a decade ago, I signed up to run the Austin Marathon. I was, I thought, more than prepared for the race. I had two 20 mile training runs under my belt as well as a dozen 15+ mile long runs in the mountains of Santa Fe, New Mexico. Mountainous and 7500 ft above sea level, my training environment was perfect. I had my race planned out and down to a science: what pace I would run, when I would choke down the gooey caffeine/carbohydrate paste that would fuel my race, when and how much to drink, everything. My goal was to finish just under four hours, and based on my training data, I was over-prepared for this modest goal. 

This was before I knew anything about the science of athletics or about strength training, I believed that endurance was the pinnacle of human athleticism, and I was about to cross off a bucket-list level endurance event.

Human endurance, as it turns out, is capricious. It is tempting to think of the human capacity for performance as a simple set of inputs and outputs. Inputs: you train your body, and you set yourself up for a well-executed performance on race day. How well you have developed and improved your overall physical capacity and what your training data says you CAN do under optimal circumstances informs your desired outcome. Performance factors are less tangible but can be observed in the efficiency with which you perform the task; how well you execute during the event tells you how close you will perform to your actual capacity. Yet even with a solid training and a well-executed plan, people often either fall short of their predictions or exceed them by significant margins, raising the issue of a kind of X-factor for endurance. 

Scientists used to think that the human body performed mechanistically. If we only understood and measured someone’s innate and trained abilities, we could predict outcomes. For an endurance event, the data usually come down to three things: VO2max, efficiency, and lactate threshold. These factors tell you how hard, fast, and long a person can endure a set pace. Using these factors, one scientist has predicted that a perfectly executed marathon, run by a person with the right genetics and running efficiency, could run a marathon in 1 hour 57 minutes and 58 seconds. (The current record sits at 2:01:39.) This human as machine view, however, has been challenged as we learn more about the connection between the mind and the body’s ability to endure.   

There is a key factor that is difficult to quantify and perpetually holds human endurance back from 100% effort. In his book “Endure: Mind, Body, and the Curiously Elastic Limits of Human Performance,” Alex Hutchinson offers this definition of endurance: Endurance is “the struggle to continue against a mounting desire to stop.” (quoting researcher Samuele Marcora’s own definition of “effort.”). Beyond simple measures of physical capacity, Hutchinson’s broad definition of endurance allows for the intangible mental aspect of suffering and perseverance. It turns out that humans are not machines. We think and feel, and how we think and feel affects our ability to persist in difficult tasks. 

If endurance is a function of what you are capable of and the practice of continuing despite the mounting desire to stop, then the idea of endurance broadens to include not just traditional endurance events like running a marathon, but life events and the choices we make every day.

Connection Between Endurance and Strength 

We tend to place endurance and strength at the opposite ends of the physical spectrum. Strength training provokes your body to build—more muscle and the structural changes that allow you to lift increasingly heavier weights. Long-distance training or events requiring a high capacity for endurance tend to make you very good at burning tissue—energy usage for the sake of using energy tending to produce catabolic responses. Indeed, layering long, slow distance training on top of your strength training program would make it difficult to build muscle and get stronger.

That would be the end of the story if, in fact, the human body was simply a machine. If that were the case, then the limits of endurance would depend entirely on the physical limits of the machine. A World’s Strongest Man competitor is not just coasting on his strength capacity, and the marathon runner is not on auto-pilot during the race. If they were machines, their ability to go and their need to stop would be based on their level of peripheral fatigue. The machine stops because it has been depleted of energy or because fatigue has accumulated to the point of the inability to continue. But there is more connecting these disparate athletes: the WSM competitor pulling a semitruck has to tap into the same mental resources as the runner who is trying to hold onto a record-setting pace. Pain, fatigue, and the depletion of energy are powerful signals but are not the ultimate regulation of effort. At some conscious or unconscious level, the human is deciding to continue despite the body’s and the brain’s growing pushback. This is perhaps why even though humans haven’t changed all that much, records that depend on the “struggle to continue” in every sport continue to fall. 

It’s a difficult question to answer, do the most elite athletes stop because they have truly reached their upper limit, or is there more to the power to endure beyond a certain point? And if even elite athletes have to learn how to endure, what chance did I ever have during my marathon attempt?

Choices and Perception

“Any task lasting longer than a dozen or so seconds requires decisions, whether conscious or unconscious, on how hard to push, and when.” -Alex Hutchinson, “Endure”

Problems started when I woke up on race day to a dead battery. My trusty GPS watch had failed to charge the night before. It had no power. I had a backup, my trusty digital watch with a simple stopwatch function. I would have to monitor my pace mile-to-mile rather than the step-by-step monitor of my GPS watch. I had planned the whole race down to the second and was minorly panicked at not being able to keep a constant track of my pace. 

All my concerns fled with the noise and excitement of the race start, and by the time the horde of runners surged over the starting line, I had let race day carry me away. I just ran. I felt so good that I was only mildly surprised when I passed the first mile-marker a minute or so ahead of my planned pace. The second mile-marker flew by, and I was still way ahead of my pace. I figured that since I felt so good, I might as well maintain this blistering pace for a while longer and crush my planned race time.

Crucial to the idea of endurance, Hutchinson writes, “is the need to override what your instincts are telling you to do (slow down, back off, give up), and the sense of elapsed time.” In my case, I should have reigned in my feelings of energy and strength brought on by the race atmosphere. I foolishly assumed that my body would regulate my effort to my energy level. Even if I started out too fast, I might finish behind my planned pace, but the outcome would be (more or less) the same. Full of energy and working hard, I had assumed a 1:1 slow down as my body accumulated fatigue. Research is now showing that these series of choices that I made and my perception of effort are what comprises that mental X-factor of endurance.

If we could name the quantity that causes you to stop before you are completely spent, it would comprise structural, mechanical, or chemical fatigue is part of a larger framework that makes up the perception of effort. The perception of effort balanced against the motivation to continue seems to govern the ability to endure physical hardship. Fatigue, pain, and other sensory signals help inform this perception, but research is bearing out that cognitive factors of perceived exertion and potential motivation determine actual effort. Endurance seems to be “the maximum effort an individual is willing to exert to satisfy a motive.” This seems oddly subjective. 

Perception is the individual’s own take on how hard or difficult something is versus how difficult that person expected the task to be. In my race, I took my first walking step at mile 10. At this point, I was on pace to obliterate not just my planned marathon time but also my previous half-marathon record. I finished climbing a modest hill, approached a water station, and without really meaning to, took a dozen or so walking steps. This surprised me. I didn’t walk during my long training runs. Why did I walk now?  I started to obsess over my heedless first 10 miles. This race was now much harder than it should have been. I wasn’t even halfway. I could feel my legs start to hurt. Each of these realizations shook my calm and confidence. As I took those few walking steps, I started to crumble.

True maximal effort is difficult to quantify. In a lab, researchers can (and have) taken muscle samples that should be “exhausted” based on the performance and subjective reporting of the subjects. They tend to find, however, that the muscles contain enough energy to continue contracting. One study showed enough ATP to continue at a high intensity for seven or eight more minutes after the subjects stopped, reporting total exhaustion. 

There is a correlation between actual exhaustion and perceived exhaustion. Rather than a linear deterioration (like I had hoped for in my foolhardy sprint to start a 26.2-mile race), people can perceive an effort as maximal to the point that they believe it is maximal, even when physiologically they could continue going.

Every marathoner knows about “the Wall.” I had been told this was the point at which your muscles run out of energy, and you have to push through the pain. Usually, hitting around mile 19, the wall is a right of passage for marathon runners. For me, it hit at mile 20. I had started walking more frequently. My legs felt on the verge of cramping, and my four hour time was no longer a reasonable goal. The pain was bad enough that I hoped my wife and family would be around the next corner so that I could stop, drive back to our room, and just lie down for a while. I had my good-enough excuses prepared, and I was more than willing to throw in the towel that day.

Sure enough, I turned the corner and there they were. As I started hobbling toward them, my wife, jogged to meet me. She ran with me and talked me down. She helped give me back my motivation and reminded me how much time and effort I had put into this. She took my obsessing over this impending failure, acknowledged it, and helped me push it to the side for later. That small break changed everything. I’d like to say I sprinted for the last 6.2 miles. I didn’t, but I finished stronger at 26.2 than I had been at that 20th-mile marker.

Endurance

I would offer a slightly different definition of endurance than Hutchinson does. If we rely on the heavy mental component of endurance, it can take many forms beyond endurance events. Endurance is the quality that allows you to master your circumstances. While this is certainly a quality necessary to complete a marathon, endurance affects how we live and pursue other goals as well. Caring for others is an act of endurance—daily choices made for the benefit of children, friends, or family that can be maintained or crushed by the perception of the effort you put into it. Pursuing health and nutritional changes are an endurance event with motivation coming from the necessity or desire to change your health. Even a long-term commitment to strength training takes endurance. Every time you choose to train and stick to your program when training feels like the last thing you want to be doing, adding up over months, then years.

Endurance is not merely a choice, but the compendium of choices that both put you on a path and take you down it. How well you endure comes from how you manage the repeating cycle of choice, action, effort, and consequence. Endurance affects “everything lasting longer than a dozen or so seconds.” (Hutchinson) Take care of yourself, stick to the plan, and remember that sometimes it takes outside help to get you to the end of the race. Good luck.