The marathon problem: why humans are not designed to run 42 kilometers

The illusion of endurance

Marathons have become a global symbol of perseverance, discipline, and triumph over limits. Every year millions of people push their bodies through 42.195 kilometers of pavement, often believing they’re pursuing health, longevity, and self-improvement. Yet behind the cultural celebration lies an uncomfortable truth: marathon running is not a marker of health, but a form of prolonged physical stress that our bodies are poorly adapted for. Despite romantic notions about “endurance evolution,” humans were never designed to endure sustained, high-intensity running over such distances.

Modern research increasingly suggests that the physiological costs of marathon running far outweigh its alleged benefits. Far from a natural or healthy activity, it’s an extreme endurance feat that places enormous strain on the heart, kidneys, joints, immune system, and endocrine balance.

The evolutionary myth

Advocates often claim humans evolved as “persistence hunters,” chasing prey over long distances. This idea, popularized by Born to Run (Christopher McDougall), has become a pseudo-scientific mantra among runners. But anthropological and physiological evidence paints a more complex picture.

While early humans were capable of walking and jogging for extended periods, they rarely did so continuously for hours. Persistence hunting was the exception, not the norm. Our ancestors relied on intelligence, cooperation, and tools more than on pure endurance. Humans are efficient walkers, not natural marathoners. Our feet, joints, and metabolism are adapted for varied movement,walking, climbing, and sprinting,not repetitive long-distance pounding on hard surfaces.

Studies in biomechanics, such as those published in The Journal of Experimental Biology (Lieberman & Bramble), show that although the human body can dissipate heat effectively, it is still limited by joint stress and muscular fatigue during prolonged running. The evolutionary “design” is about versatility, not specialization. The romantic image of humans as natural long-distance runners is a myth born from modern fitness marketing, not evolutionary fact.

The cardiac toll

One of the most concerning aspects of marathon running is its effect on the heart. During a marathon, the heart must pump enormous volumes of blood for hours. This extreme strain can cause temporary heart muscle damage and even scarring.

Research published in The Journal of the American College of Cardiology (Mohlenkamp et al.) found that chronic marathoners often develop myocardial fibrosis,scarring of the heart tissue that can increase the risk of arrhythmia and cardiac arrest. Even short-term studies show elevated cardiac enzymes and reduced ventricular function after long-distance races.

The notion that “cardio is good for the heart” holds true only within moderate limits. Beyond those limits, endurance exercise becomes cardiotoxic. The paradox is stark: those chasing cardiovascular fitness through extreme endurance may be damaging the very organ they’re trying to protect.

Immune suppression and inflammation

A marathon is a controlled trauma. The body reacts to it as if it were under attack. The immune system weakens in the days following prolonged endurance effort, creating what scientists call the “open window” of immune suppression.

During this period, white blood cell counts drop, cortisol levels spike, and inflammation markers surge. This is why runners often experience colds, infections, or fever after a race. A study in Exercise Immunology Review (Nieman) found that marathoners are up to six times more likely to develop upper respiratory infections in the week after a race than non-runners.

Inflammation is another overlooked consequence. Marathon running causes extensive micro-tears in muscle fibers, releases free radicals, and elevates C-reactive protein (CRP) levels. Chronic inflammation is linked to accelerated aging, weakened immunity, and metabolic disruption,hardly the hallmarks of good health.

Joint destruction and muscular imbalance

The repetitive impact of running thousands of steps on hard pavement devastates joints and connective tissues. Knees, hips, and ankles bear the brunt of forces several times the body’s weight.

Cartilage doesn’t regenerate easily. Over time, this mechanical wear leads to osteoarthritis, tendonitis, and chronic pain. Contrary to what running enthusiasts claim, most studies find no joint-protective benefit from long-distance running, especially in amateur athletes who lack perfect biomechanics. The body may adapt for a while, but eventually, the accumulated damage surpasses its ability to repair.

Moreover, marathon training creates muscular imbalance. The repetitive motion strengthens certain muscle groups (like the calves and quadriceps) while neglecting others (like the glutes and core stabilizers). This imbalance alters posture, strains the lower back, and increases susceptibility to injury. What is marketed as “full-body endurance” is, in fact, one of the least balanced forms of movement imaginable.

The metabolic and hormonal crash

Marathon training forces the body into a chronic catabolic state, meaning it breaks down muscle tissue for fuel. Cortisol, the stress hormone, rises sharply during endurance exercise, suppressing testosterone and impairing recovery.

In women, prolonged endurance training can disrupt menstrual cycles and reduce bone density (a condition known as the “female athlete triad”). In men, it can lead to decreased libido, low testosterone, and impaired metabolic function.

The popular belief that marathoners are paragons of health is contradicted by these biochemical realities. Their bodies may look lean, but the internal hormonal chaos tells a different story. The constant depletion of glycogen, electrolytes, and muscle tissue leaves many endurance athletes metabolically fragile and prone to chronic fatigue.

The psychological cost

Beyond physiology, marathon culture promotes a toxic mindset: that suffering equals virtue. Endurance events are glorified as moral achievements, reinforcing the illusion that pain and exhaustion are proofs of character.

This culture encourages people to override bodily warning signs in pursuit of artificial goals,personal records, medals, social validation. It’s not discipline but self-denial disguised as virtue. Studies in Frontiers in Psychology suggest that endurance athletes often show higher levels of obsessive-compulsive traits and body dysmorphia. The marathon becomes not a celebration of life, but a ritual of self-punishment.

The corporate machine behind endurance culture

The modern marathon is also a business. Sportswear brands, supplement companies, event organizers, and health media have turned it into a lucrative industry. The narrative that “anyone can run a marathon” sells shoes, gels, watches, and insurance.

This commercialization feeds on insecurity: the idea that health and self-worth are achieved through physical extremes. The irony is that the entire system depends on people ignoring the growing evidence of harm. Just as the tobacco industry once equated smoking with sophistication, the fitness industry markets marathon running as the ultimate badge of vitality.

Health is not built through extremity but through balance,adequate movement, strength, rest, and nourishment. Marathons defy this balance. They reward obsession over wellbeing, pain over prudence.

The truth about “runner’s high”

Much of the appeal of marathon running comes from the so-called “runner’s high,” a euphoric state linked to endorphin and endocannabinoid release. But this chemical reward is not a sign of health,it’s a coping mechanism for pain.

The brain releases these substances to mask suffering, not to celebrate fitness. In essence, marathoners chase a neurochemical illusion that their bodies interpret as survival relief, not joy. Over time, this can lead to dependence on physical extremes to feel mentally balanced, blurring the line between healthy activity and addiction.

A healthier perspective on movement

Human health thrives on moderate, varied, and sustainable movement: walking, resistance training, sprinting, and mobility work. These forms of activity reflect our biological design,short bursts of intensity interspersed with rest and recovery.

Walking, for instance, engages the cardiovascular system efficiently without overtaxing joints. Strength training improves metabolism and bone density. Flexibility and balance exercises preserve functionality with age. These are the movements our ancestors practiced naturally, not four-hour slogs on asphalt.

The future of genuine fitness lies not in endurance spectacle but in harmony with biology. The body was never meant to be a machine of relentless mileage. True health is measured not by finish lines, but by vitality, resilience, and longevity.

The real finish line

The marathon is a cultural myth dressed as a medical truth. It glorifies excess and punishes moderation. While finishing one may feel empowering, that feeling often comes at the expense of long-term health.

Humans were not built for sustained punishment. We are designed for movement, not for masochism. To reclaim what health truly means, we must stop celebrating exhaustion as a virtue and start recognizing that balance, not extremity, is the essence of human strength.