Editor’s note: Beyond Limits is a new VeloNews Voices project featuring Allen Lim, PhD, that includes videos, podcasts, photos and written stories. Beyond Limits is about the exploration of human performance and human possibility. This project is made possible by sponsorship from Skratch Labs and Saris.
Pushing beyond our personal limits has always been part of the human experience. It’s made us the dominant species on planet Earth, giving us unimaginable comforts. Because of this comfort, being uncomfortable, by engaging in hard physical training, has now become something we choose, rather than something we just survive. It has also become a social health imperative.
To better understand the training process and how we arrived here, it helps to understand some of its history, which for many, begins with Milo of Croton – a wrestler from the 6th century BC who was an icon of the ancient Greek Olympiad. As legend has it, each season Milo would begin training by lifting a baby calf above his head. As the calf grew, so did his strength, until he was able to lift a full-grown cow. Today, we call this incremental adaptation to an increasing workload “progression.”
Progressively increasing your training load is a time-tested way to improve, whether with a growing calf or longer, harder intervals. | Illustration: Haley Midzor
But, the modern basis of exercise physiology, really began with a Renaissance physician named Paracelsus (1493–1541), who’s famous for the quote, “sola dosis facit venenum” or “the dose makes the poison.”
His statement forms the backbone of a concept called “Hormesis.” It’s the idea that something that might be good for you in a small dose, might actually kill you in a larger dose. In fact, anything that we think of as healthy or even essential for life, can kill us. Water, food, rest, and even training in too high of a dose can hurt us. Moreover, as we adapt to something, it takes more of that something to create the same response. What Paracelsus taught us is that nothing is either good or bad without context. And in the context of the modern world, abundance has led to such high levels of physical inactivity and obesity, that excess is today’s modern plague.
Measuring energy, in work and in food
There was, however, a time when the possibility of starvation was the existential threat facing America. That threat ushered in the modern era of human performance, as scientists sought to measure the energy needs associated with physical work along with the energy capacity of our food supply.
Much of the credit for this work goes to Wilbur Olin Atwater (1844-1907), who developed the first systems for measuring human metabolic rate at Wesleyan College and who also created systems for measuring the energy in food. To measure metabolic rate, he built a chamber big enough for a human that measured the heat created, oxygen consumed, and carbon dioxide produced during rest and simple tasks. To measure energy in food, he literally detonated it under high pressure in something called a bomb calorimeter to get the total or gross energy. Then he developed a system for calculating the available energy from carbohydrate, fat, and protein that could be digested and utilized by humans. His work helped usher in our use of the calorie, the United States Food & Drug Administration, food labels, the Food Pyramid, and federal policies that helped abate childhood starvation.
It was the foundation of Atwater’s work that then led to the creation of the Harvard Fatigue Laboratory, which was founded by Lawrence Joseph Henderson (1878-1942) and operated from 1927 to 1947. The Harvard Fatigue Laboratory brought together chemists, psychologists, biologists, sociologists, physiologists, and anthropologists to study human fatigue in order to solve problems related to agriculture, labor, and industry.
The laboratory took a multi-faceted approach, researching blood chemistry, nutrition, aging, and environmental stressors like altitude, heat, and cold. They also ushered in the use of modern exercise physiology tools and equipment, building a climate room, altitude chamber, treadmills, equipment for measuring oxygen consumption, and even bicycle ergometers that could measure power output. All of this led to practical recommendations on human performance. During World War II, the Harvard Fatigue Laboratory gave the United States Military over 150 recommendations on nutrition, clothing, and survival equipment and techniques.
The beginning of stress
After World War II, it was the work of Hans Selye (1907-1982) – a doctor, chemist, endocrinologist, and psychologist – that pulled together work from Paracelsus and contemporary science to give us a more unified model for human performance with a single concept called “stress.” As common as the word stress is today, it was Hans Selye who first coined the term after observing as a medical student that patients suffering from different diseases often had the same signs and symptoms.
The Inverted U illustrates that stress can be a positive or a negative thing, depending on the dose. | Illustration: Haley Midzor
For Hans Selye, the word stress encompassed a basic response to any noxious stimulus. He used to the term “stressor” to refer to the stimulus and the term “stress” to refer to the acute and chronic response through a model he called the “General Adaptation Syndrome.” The General Adaptation Syndrome described three stages to a stressor. The first is the Alarm Reaction, which is the acute response. An increase in heart rate, metabolic rate, fear, adrenaline, and excitement are examples of this alarm. The second stage is the Resistance stage, where the body begins to resist and adapt. The third stage is the Exhaustion stage where the body cracks and fails to cope.
Of note, before the word stress was used by Selye, the closest term for stress came from two Chinese characters – one meaning “opportunity” and one meaning “danger” – that collectively meant “crisis.” It’s fitting then that Selye would develop a theory he called the “Inverted U Hypothesis,” which described stress as both a positive and a negative. Positive stress was termed “eustress” while negative stress was termed “distress.” The Inverted U Hypothesis described a model where some stress was required for optimal performance by eliciting a beneficial alarm and resistance response but, too much stress caused a decline or exhaustion.
The left character represents danger. The right character represents opportunity. Together they represent crisis – a predecessor for the term stress.
Popcorn and your training plan
When I first started college and began living in a dorm, I started thinking about the Inverted U Hypothesis through the seemingly disconnected act of microwaving popcorn in a bag. To me, the un-popped kernels represented someone’s genetic potential. Do nothing to stimulate those kernels and we just have a bag of kernels. We don’t perform and can even get sick. But, start applying some heat or a specific stressor and those kernels pop into delicious popcorn (eustress). Unfortunately, if you apply too much heat, you get what I call the “stench of failure” – burnt popcorn that ruins performance (distress). This simple dose-response or cause and effect paradigm is effectively the very basis of all training and what inspired me to start using portable power meters to help cyclists pop all of their kernels without burning any hard-earned popcorn.
Similar to Selye’s Inverted U, you can think of cycling training like popping popcorn: too little or too much heat is a bad thing. | Illustration: Haley Midzor
Today, outside of managing this dose-response relationship, the core tenants of training can be defined through three key ideas – specificity, individuality, and progression or periodization. Specificity refers to the idea that adaptations are highly specific to a task and environment. If you want to be a better cyclist, you have to ride, not lift cows. And even within cycling, replicating the specific demands of a task like climbing in the mountains versus time trialing on the flats creates distinct adaptations. Individuality refers to the idea that we are each unique and that our response to a given stressor or training load might be different from someone else. Finally, progression refers to the idea that we need to manage how much stress we take on at any given time, to stay in a state of positive eustress rather than chronic distress. Breaking training into periods of hard work and easy work as well as periods where one physiological system is emphasized over another is a key aspect of proper progression, and often referred to as periodization.
Not perfect, but better
It’s with all of this as background that my hope for Beyond Limits is to help us all optimize our potential so we can live healthier and happier lives. While my goal as a sport scientist and coach has always been about pushing beyond known human limits, the deep irony of my own experience has been that the only way to achieve an extreme goal is to avoid extremism. For me, elevating human potential and performance has never been about being the best, it’s been about exploring possibility – about learning how to be better.
Key to this is my belief that better is not about perfection, it’s about progress. Within the realm of science, that progress has been built on a long and historic legacy of thinkers and doers, who have given us a foundation of data that we generally represent as an average.
But, despite this rich history, it’s important to realize that as individuals the average rarely applies and that if we want to progress as a society, we need to think beyond whatever average is. Ultimately, science is not a set of facts, it’s a process – a method for finding solutions.
With that in mind, my ultimate hope for Beyond Limits is to teach each of you to listen to your own history around performance. To think, to test, and to learn. It’s the only way we can become better throughout our lifespan.
For more Beyond Limits, visit the Beyond Limits hub
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