Mainstream medicine has spent decades promoting the idea that “more exercise is always better.” Endurance events like marathons and ultramarathons are held up as the pinnacle of human health and achievement. Ray has always emphasized a very different view: moderate, concentric, glycogen-bound exercise is beneficial, but strenuous endurance exercise is harmful. The latter dramatically raises stress hormones (cortisol, adrenaline), increases lipid peroxidation, and leads to muscle and organ damage. The study below, published in Blood Red Cells & Iron by the American Society of Hematology, directly confirms this position. Researchers found that ultramarathons damage red blood cells, making them less flexible and more prone to breakdown , with evidence of accelerated aging that worsens with longer distances. This is exactly what bioenergetics predicts: prolonged reliance on fatty acid oxidation generates excessive oxidative stress, damages cellular components, and accelerates aging rather than retarding it.
As the study below demonstrates, researchers analyzed blood samples from runners before and after two demanding races: a 40 km (25 mile) race and a 171 km (106 mile) ultramarathon. They found clear evidence of red blood cell injury driven by both mechanical stress (from intense blood flow) and molecular damage linked to inflammation and oxidative stress. After the races, red blood cells became less flexible — a critical problem because these cells must bend to pass through tiny blood vessels to deliver oxygen. Evidence of accelerated aging and increased breakdown of red blood cells was visible after the 40 km race and was even more pronounced among athletes who completed the 171 km event.
This finding directly validates the bioenergetic distinction between beneficial and harmful exercise:
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Concentric, glycogen-bound exercise (short, intense, glucose-fueled) is protective. This type of exercise relies on glucose oxidation, which is clean, efficient, and generates far fewer reactive oxygen species. It supports mitochondrial function and metabolic rate without causing excessive stress.
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Strenuous endurance exercise (marathons, ultramarathons) forces reliance on fatty acid oxidation. Fat oxidation generates more ROS per ATP than glucose oxidation, increases catecholamines and cortisol, and leads to lipid peroxidation, muscle protein breakdown, and immunosuppression. The study confirms that this type of exercise damages red blood cells — the very cells responsible for delivering oxygen to tissues.
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The “more is better” exercise dogma is false. The researchers explicitly note that “at some point between marathon and ultra-marathon distances, the damage really starts to take hold.” This is a rare admission from mainstream science that exercise is not beneficial or even benign at any level — there is a threshold beyond which it becomes harmful.
The study did not provide specific dosing or human-equivalent calculations, as it was an observational study of athletes. However, the practical implications are clear: avoid strenuous endurance events that last for hours and rely on fat oxidation. Instead, focus on short, intense, concentric exercise that depletes glycogen and promotes glucose oxidation — such as weight training, sprints, or brief high-intensity intervals. Ray has long recommended walking (which is low-stress and pro-metabolic) and avoiding the “exhaustion” model of exercise that dominates mainstream fitness culture.
The researchers note that they “don’t know how long it takes for the body to repair that damage, if that damage has a long-term impact, and whether that impact is good or bad.” From a bioenergetic perspective, the answer is clear: chronic oxidative damage accelerates aging , and there is nothing “good” about damaging the most abundant cells in your body. The study also found that “longer races may lead to greater loss of red blood cells and more damage to those that remain in circulation” — a dose-dependent effect where more exercise produces worse outcomes.
http://dx.doi.org/10.1016/j.brci.2026.100055
https://www.sciencedaily.com/releases/2026/02/260221060946.htm
“…New research suggests ultramarathons can alter red blood cells in ways that make them less flexible and more prone to breakdown , potentially interfering with how they deliver oxygen throughout the body.”
“…Scientists found signs of both mechanical stress from intense blood flow and molecular damage linked to inflammation and oxidative stress .”
“…’Participating in events like these can cause general inflammation in the body and damage red blood cells ,’ said the study’s lead author, Travis Nemkov, PhD.”
“…Evidence of accelerated aging and increased breakdown of red blood cells was visible after the 40 kilometer race and was even more pronounced among athletes who completed the 171 kilometer event.”
“…’At some point between marathon and ultra-marathon distances, the damage really starts to take hold ,’ said Dr. Nemkov. ‘We’ve observed this damage happening, but we don’t know how long it takes for the body to repair that damage, if that damage has a long-term impact, and whether that impact is good or bad.'”
“…’This study shows that extreme endurance exercise pushes red blood cells toward accelerated aging through mechanisms that mirror what we observe during blood storage.'”
