Goal creates the functioning
A new way to understand physiology.
Living organisms have always been seen as a perfect example of design tailored to their needs, serving as inspiration for creating the most useful and sophisticated machines.
Biomimetics is the scientific discipline that tries to mimic Nature to develop innovative technological solutions, using biological patterns, systems, and processes that have been refined over millions of years of evolution as a reference.
For instance, modern airplanes are inspired by bird wings, the nose of high-speed trains by the kingfisher's beak, Velcro by how burdock seeds stick, competitive swimsuits by shark skin, helicopters by the shape of dragonflies, and new hexagonal building designs by beehives, among countless other examples.
Using biological organisms as inspiration to create increasingly sophisticated machines led us to mistakenly believe that the relationship was bidirectional. Thus, because machines resembled organisms, it was assumed that organisms resembled machines.
"Man is a thinking machine."
René Descartes.
Since Descartes' work "The Man Machine" in the 17th century, the concept of the organism as a sophisticated machine has dominated science and, consequently, medicine. This formed the basis of what we now call the biomedical model.
According to this traditional biomedical model, the organism is an ultra-sophisticated machine whose mechanisms we have yet to fully understand. Therefore, our job as scientists is to gradually uncover the instruction manual that guides it.
However, the more we learn, the more we realize that this reductionist view of the organism doesn't give us the answers we expected.
Viewing the organism as a machine assumes that, like a machine, it can be broken down into parts and reassembled. It presupposes that each part of the organism has a predetermined function and that we can replace a worn-out part with a new one.
But new discoveries challenge this view. An organism can perform the same function using different parts of the system, with various synergies or configurations, and each of these parts can lead to different behaviors.
Each year, we discover new proteins, hormones, or interrelationships between parts of the organism that never fully clarify anything. As is often said in physics: we always think we are on the verge of discovering the last particle we need to understand the Universe, and every time we do, we realize that more questions remain unanswered.
What if our models are deceiving us? What if this idea of thresholds, VO2 max, different molecular adaptations... while partially true, prevents us from seeking a better interpretation of reality?
Often, we only find what we're looking for because we only search for what we know. Some studies find, for example, that fatigue is much higher 10 watts above each threshold than 10 watts just below, without considering that this could happen at any intensity point, regardless of whether it's a threshold or not. Or the ability to measure lactate makes us believe there is a point at which fatigue spikes, without considering the practical implications if the slope of the logarithmic power curve doesn't change above or below this point.
In the coming years, we will continue to have amazing molecular discoveries that will win several Nobel Prizes, but these won't fully explain the organism's function. If we ever understand the molecular mechanisms that make the organism work, we will realize that we also need to understand these relationships on atomic scales, and decades later, probably subatomic scales, to truly understand how an organism functions and provide an adequate response through brute force.
And the vision of man-as-machine overlooks a crucial reality: the organism is not an artifact planned by a grand designer, top-down, like a machine. No, organisms, as Complex Systems, have formed from the bottom up: from the union of the smallest parts to the largest.
Organisms have emerged through the autonomous organization of the smallest parts. Atoms formed molecules, molecules formed organelles, organelles formed cells, and these cells organized with others, specializing into different tissues, organs, systems, and organisms.
Why have they self-organized in certain ways and not others? Why, although made of the same matter, are cows vegetarians and wolves carnivores?
Because of the environment in which each has had to evolve.
Complex Systems naturally tend towards the state with the lowest energy cost, known as the principle of minimum energy. Lightning follows paths of least resistance, and similarly, the cells of an organism naturally tend, through trial and error, towards a state of equilibrium: the point where they find the lowest energy expenditure that allows them to maintain their own structure.
This quest for the least energetically costly state is never fully achieved because it occurs in a dynamic environment where both the surroundings and competitors change.
This search for stability in a dynamic environment is what drives adaptation.
Nature has found mechanisms to solve this problem through the adaptation of species. Except for a few exceptions, a species tends to evolve to become increasingly adapted to the ecological niche it inhabits. Animals without access to water have developed adaptations to need less water. Prey animals have more offspring, while predators are more territorial. Each physiology in the animal kingdom has self-organized to face different restrictions and environments, shaping its unique physiology.
Thus, we can say that it's not that a complex system actively adapts, but rather its constraints force it to do so to maintain equilibrium, just like opening the gates of a dam causes water to flow because it's the path of least energy resistance.
This is why attempting to break down the organism into parts as if it were a machine is so futile. There is no ideal way to assemble the parts; instead, the parts have organized themselves to fulfill a greater function. Knowing the Krebs cycle is only useful for teaching it to others.
"Goal is more important than functioning"
I highly doubt we will be able to unravel all the interrelationships between an organism's parts and write its instruction manual (especially since this manual would be different for each organism). However, if we can understand the stimuli, determinants, and constraints that have caused this internal configuration, which seems much more manageable, we will be able to provide what it needs. "I don't want high levels of oxytocin; I want to feel well."
By understanding the purpose, the reason that has led the organism to evolve for survival, we can finally have correct and satisfactory answers and reactions to the big questions about training and health.
For example, in a person chronically exposed to low-carb diets since childhood, the organism can generate a series of epigenetic and molecular responses that allow it to function well in this environment. In contrast, a person who has never experienced hunger and is adapted to exercising with high glucose availability will develop different adaptations. In the end, both types of people can perform the same tasks with different internal configurations, which is why the molecular view of exercise can fail when extrapolating the average to the individual.
By adapting from the bottom up, a new reality emerges: what we can modify is not the parts, but the stimulus.
Another example: Zone 2 training doesn’t work because it's the intensity at which the mitochondria oxidize more fatty acids and certain transporters function optimally. No, Zone 2 works because covering long distances daily is a stimulus we had to evolve to handle. The environment created the stimulus, and this stimulus shaped our physiology!
Given the above, we must be aware that the analogy of exercise as a car is inadequate. Instead, we should see it more like a vast ecosystem, where organs act like species that together maintain the ecosystem. For example, the survival of a forest depends not just on trees. Trees couldn’t reproduce without birds dispersing their seeds, couldn’t nourish themselves without bacteria living in their roots, and couldn’t withstand droughts without the network of mycorrhizae connecting them.
When faced with stress, the organism can act like an ecosystem, functioning as an integrated whole. Damage and overload in certain structures can be compensated for by the involvement of others, until parts that initially wouldn't be exposed to the stress end up being affected.
For instance, energy deprivation and fasting are initially expected to have effects at the cellular level, in adipocytes, and through glucagon secretion by the pancreas to convert fatty acids into energy in the mitochondria. But when deprivation is severe, new parts of the organism come into play to compensate for the damage: muscle mass degrades, and amino acids are used as fuel; immune, endocrine, or reproductive functions slow down or halt to conserve scarce energy needed more urgently by the brain or heart to keep us alive; and even our thoughts change, becoming more focused on the urgency of finding food and the reluctance to engage in any activity that doesn’t directly lead to obtaining it.
It’s a dance of systems that help and influence each other. Each change in one part can end up causing reactions in all the others if the magnitude of the stress is high enough. Just as wolves can change the course of a river, a nutritional stimulus can change your entire life: the mere intake or avoidance of the birth control pill can alter who a woman falls in love with.
In these complex systems, synchronization is as vital as organization: an organism functions properly through the synergies between its different structures. It’s like a grand orchestra: it doesn’t matter if you have the best musicians in the world; their sound would be unpleasant if each played in isolation or out of sync with the others. What gives value to the ensemble and allows it to behave adaptively is the synchronization between the musicians, between the parts.
Thanks for being a critical thinker,
Manu