Testing Limits

All humans are limited.


Photos Unsplash

The Rational Mind and The Emotional Heart

It was a scorching Friday afternoon when I made the painful decision to complete a 5km virtual race at a nearby park connector. In all honesty, I was reluctant and dragged my feet out the front door. The temperature hovered around 35 degrees celcius with humidity levels at 90%. Cloud cover was non-existent. As I laced up my shoes, a sense of dread and trepidation washed over me. While the distance itself wasn’t daunting, my head simply wasn’t in the game. My rational mind attempted to assuage me by reasoning how it would probably take less than 30 minutes to complete the run. My emotional heart made a desperate plea that what I was about to undertake was a terrible idea. Alas, I did not consider how this inner conflict would affect my performance.

Curiously Elastic Limits

As athletes, how should we decide whether it is appropriate for us to push beyond our perceived limits? I myself have always relied on intuitions in deciding whether or not to go guns blazing. History has enlightened me that this is a terrible strategy; more often than not, I crashed and burned before the finish line. But such gambles were what made my races memorable.

My dissatisfaction fuelled my determination to find out more about the limits of human endurance. Fortunately for me, Alex Hutchinson shared a similar research interest. His book, Endure: Mind, Body And The Curiously Elastic Limits Of Human Performance, analysed years of comprehensive studies conducted by sport scientists and researchers. Going beyond the mechanistic view of human bodies, Hutchinson argued that a key element in endurance is how our brain reacts to distress signals and, more interestingly, that the brain’s responses can be trained.

In this article, I review three areas of Hutchinson’s findings that most athletes in Singapore can intimately relate to: pain, heat and thirst. I will leave the discussion of Hutchinson’s methods of training the brain to another time.

Pain: “Shut up, legs!”

In 1664, philosopher René Decartes explained that there’s a one-to-one correspondence between the physical injury you’ve suffered and the pain you feel. In his imagery, if you stepped on a Lego brick, a message is sent that rings a bell in your brain. A simple and intuitive theory, but flawed: the same injury can provoke different reactions in different people, or even in the same person at different times. Also, how do amputees with phantom limb syndrome experience real pain that has no physical source?

If pain without physical injury can be experienced, then perhaps pain is fundamentally subjective and dependent on situational context. Consider how stress and anxiety can activate an array of brain chemicals that dull or block pain. This is evident when we’re being chased by a pack of rabid dogs. In this view, elite athletes are humanised as people who have trained themselves to ‘get comfortable being uncomfortable’ - they push themselves to a darker place, and stay there longer than most people are willing to tolerate.

Heat: Nature’s Safety Break

To cool down, our body shunts blood toward the skin where it releases heat. However, this starves our gut and other internal organs of blood and oxygen. Eventually, toxins that are normally corralled in the gut begin to enter into the bloodstream, triggering a system-wide inflammatory surge. Heatstroke isn’t merely about getting hot; it’s about a surge of inflammation that disables the body’s normal temperature defences.

Most people view heatstroke as a cascading sequence of events: first you feel hot, then you’re uncomfortably hot, then heat exhaustion occurs, and finally, if you don’t stop, heatstroke. However, evidences suggest that most people are physically incapable of pushing their temperature to anywhere near 43 degrees celcius. Such is feeling of your body being unresponsive to your desire to push harder. To go beyond that, something different must be going on. Something that inhibits your body’s ability to regulate temperature.

Hutchinson discovered that under hot conditions, brain-altering drugs (Paxil, Prozac, Celexa, Effexor, Wellbutrin, Ritalin, and others) that increased concentrations of the neurotransmitter dopamine in the brain had a dramatic effect on the subjects’ perception of heat. Studies revealed that these subjects were not only able to push themselves further and harder (causing their temperatures to rise beyond their usual critical threshold), they reported not feeling hotter. In other words, brain-altering drugs successfully disengaged the subjects’ ‘safety break’.

Thirst: Heatstroke without Dehydration, Dehydration without Heatstroke

Contrary to popular belief, you don’t feel thirsty because you’re losing fluids. Instead of monitoring fluid levels, your body monitors plasmaosmolality - the concentration of small particles such as sodium and other electrolytes in your blood. As you get dehydrated, blood concentration increases; your body secretes antidiuretic hormones that cause your kidneys to reabsorb water, and making you thirsty. Unlike fluid levels, plasma osmolality is tightly regulated as part of your body’s homeostatic measures.

Hyponatremia (water intoxication) risks fatality when your body’s plasma osmolality is thrown out of balance from drinking too much. Likewise, such is the risk of severe dehydration. People often assume that dehydration and heatstroke are entwined, but it’s possible to get heatstroke without dehydration, and dehydration without heatstroke. As it turned out, dehydration is a greater concern for longer races (more time to sweat) while heatstroke is most common in shorter races (a blistering pace drives your core temperature up faster than it takes for your body to get seriously dehydrated). Alas, it is thirst, not dehydration, that increases your perceived effort and compels you to slow down.

From Research to Reality

So, how did my 5km virtual race turn out? Pretty much miserable. In terms of pain management, I lacked the willpower to maintain a race-paced effort. My mind constantly reminded me of how much pain I was experiencing and how minute a virtual race result was compared to the result of a physical race. It was negative self-talk galore. So much for ‘getting comfortable being uncomfortable’.

My targeted pace was 3:30mins/km, a pace that I ran at close to a year ago for another virtual race. Back then, I ran in the evening - cool, breezy and shaded. This time, I ran in a figurative sauna. I briefly contemplated the risk of heatstroke but with a mind that’s easily fooled by probabilities, I discarded said risk as an unlikely event. While such an incident did not befall upon me, I experienced firsthand an inability to run any faster than 3:45mins/km. Going faster than that felt akin to running through a concrete wall. My body simply wasn’t able to ramp up the pace. As the minutes passed, I inevitable slowed.

As it turned out, I did one thing right: I hydrated myself before the run. Did it make a difference to the overall race time? Possibly. I never felt the urge to drink throughout the 18 minutes 45 seconds ordeal. Yes, I felt myself burning under the sun but not once did I feel the urge to stop for water.

Do it all again? Heck no.

Memorable? Definitely.


Lester Tan’s interest in long-distance events primarily stem from a desire to test the limits of human endurance. While many may dread the longer distances for a variety of reasons, he views it as a cathartic experience. He says, “Endurance racing liberates my mind of the stresses of daily life and teaches me to appreciate the joys derived from the present moment.”



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