For decades, ageing has been widely associated with inevitable physical decline. Muscle strength weakens, endurance drops, and recovery slows. This narrative has shaped not only medical understanding but also societal expectations, that physical performance after 70 or 80 is defined largely by limitation rather than capability. Even among healthy individuals, reduced aerobic capacity and cardiovascular efficiency are considered unavoidable consequences of ageing.
But emerging research is beginning to challenge this assumption. A recent case study published in Frontiers in Physiology examined the physiology of an “81-year-old male runner who, in 2025, set a new world record in the 50-km race” for the 80+ category, completing the distance in 4 hours, 47 minutes, and 39 seconds at an average speed of 10.5 km per hour.
The athlete examined in the study is Juan López García, a former car mechanic from Toledo, Spain, who began running only at the age of 66 after retirement and initially struggled to complete even a mile. Over the next 15 years, he transformed into a world-record-holding ultramarathon runner and, at 82, continues to challenge the limits of endurance in advanced age.
The study, titled ‘Exploring the physiological limits of ageing: a case study of the male 50-km world record in the 80+ age category,’ offers rare insights into how the human body can maintain exceptional endurance even into advanced age.
What the study reveals
To understand what enabled such extraordinary performance, scientists conducted a detailed physiological assessment of the runner two weeks after his world-record achievement. Their aim was “to examine the physiological responses to exercise and performance characteristics of an 81-year-old male runner” and identify the biological factors that contributed to his endurance.
The findings revealed a remarkably preserved aerobic capacity. The athlete’s maximal oxygen uptake, or VO₂max - a key measure of cardiovascular fitness, was recorded at 52.8 mL per kg per minute, achieved at a running speed of 13.2 km per hour. This value is extraordinary for someone in his eighties. In fact, researchers noted that it was “to our knowledge the highest recorded in octogenarians, equivalent to the 70th percentile for healthy males aged 20–30 years.”
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VO₂ max is widely considered one of the most important indicators of endurance performance and overall health. It reflects the body’s ability to transport and use oxygen during exercise. Higher VO₂max levels are associated with greater stamina, improved cardiovascular function, and lower mortality risk. The fact that this athlete’s VO₂max resembled that of much younger adults highlights how ageing does not necessarily impose fixed physiological limits.
The study also found that the athlete reached his lactate threshold - the point at which fatigue-causing lactate accumulates rapidly, at 10.5 km per hour. This allowed him to sustain high speeds without premature fatigue. His maximal fat oxidation rate was recorded at 0.55 grams per minute, occurring at 84% of VO₂max. This indicates an exceptional ability to use fat as a fuel source during endurance exercise.
Fat oxidation is especially important in long-distance events like ultramarathons. Efficient fat metabolism allows athletes to conserve limited carbohydrate stores and maintain energy levels for longer periods. In older adults, fat metabolism often declines, making sustained endurance more difficult. However, in this case, the athlete retained a highly efficient metabolic system.
Running economy - the energy required to maintain a given speed, was measured at 237.5 mL per kg per kilometre. While slightly lower than elite younger athletes, it was comparable to that of recreational runners. This suggests that his performance was driven less by mechanical efficiency and more by exceptional physiological capacity.
The researchers also examined cardiovascular and muscular oxygen delivery. During cycling tests, the athlete’s peak oxygen uptake reached 2.510 litres per minute, and his peak cardiac output was 15.3 litres per minute. His arterial-venous oxygen difference was measured at 16.4 mL per decilitre, indicating highly effective oxygen extraction by muscles.
Near-infrared spectroscopy revealed that his skeletal muscle, particularly the vastus lateralis muscle in the thigh, had exceptional oxidative capacity and oxygen diffusion efficiency. Measurements of muscle oxygen dynamics showed strong performance under both high and low oxygen conditions, suggesting robust cellular adaptations.
According to the researchers, “Analyses on the limiting factors to VO₂max suggest that his exceptional performance was mostly due to the final steps of the oxygen cascade.” This cascade refers to the process by which oxygen moves from the air into the lungs, into the bloodstream, and finally into muscle cells where it is used for energy production.
Importantly, researchers highlighted the role of muscle adaptation. They noted that “extraordinary skeletal muscle adaptation such as high oxidative and diffusive capacity” allowed efficient oxygen use at the cellular level. These adaptations enabled the athlete’s muscles to extract and utilise oxygen more effectively than typical older individuals.
Limitations of the study
While the findings are compelling, researchers caution against broad generalizations. This study examined only a single individual, making it difficult to determine how widely these results apply to the general population.
As the authors explained, “This study captures an informative snapshot of the athlete’s physiology close to the 50-km record.” The testing was conducted two weeks after the race, which allowed researchers to assess physiological characteristics without the immediate fatigue associated with ultramarathon running.
However, the study lacked long-term data. Researchers acknowledged that “we did not have longitudinal data that allowed us to trace the developmental trajectory or identify factors that shaped the physiological adaptations underlying this performance.” Without tracking the athlete over decades, it is impossible to determine exactly how his body developed such exceptional endurance.
Genetics may also have played a role. The researchers noted, “we cannot exclude that the present athlete had unique genomic markers related to endurance performance.” Certain genetic traits can enhance oxygen transport, muscle efficiency, and metabolic performance, potentially giving some individuals a natural advantage.
Another limitation involves differences between laboratory testing and real-world performance. Running economy was assessed on a treadmill with a slight incline to simulate outdoor running. However, researchers acknowledged that “there is likely a significant difference in running economy when running on a trail vs. running the same speed on a treadmill.”
The methods used to estimate oxygen delivery and muscle function were primarily non-invasive. While these techniques are reliable, they involve assumptions about blood composition and oxygen transport. The researchers noted that invasive testing methods could provide more precise measurements, but were not used in this case.
Additionally, oxygen delivery to muscles was estimated based partly on haemoglobin concentration in venous blood. However, endurance training can increase plasma volume, which dilutes haemoglobin levels. This can affect estimates of oxygen transport capacity.
The authors also explained that some calculations relied on modelling tools such as the Helsinki O₂ Pathway Tool, which estimates oxygen delivery and diffusion across the body. While useful, these tools cannot fully capture the detailed physiological responses occurring in specific muscle groups during actual running.
Despite these limitations, researchers emphasised that the consistency between different measurements supports the validity of their conclusions. They also suggested that future studies should include long-term tracking of athletes and explore the role of genetics in endurance performance at advanced ages.
Challenging the idea of inevitable physical decline
One of the most striking examples of endurance in advanced age is Bob Smith, an 80-year-old grandfather and former headmaster from Upminster, who has completed multiple London Marathons well into his later years. Smith went viral in 2024, at the age of 79, after a video of him crossing the London Marathon finish line gained widespread attention on TikTok. His journey into marathon running began in 1992, when he was encouraged to participate to support a colleague whose daughter was blind and deaf, raising funds for Sense, a charity that supports people with complex disabilities. What began as a single effort evolved into a long-term commitment.
Examples from India also highlight the growing participation of older adults in endurance events. During the 2023 Tata Mumbai Marathon, more than 55,000 participants took part, including senior citizens.
Among them was Bharti, an 80-year-old woman whose performance captured widespread attention. Wearing a saree and sneakers and carrying the Indian tricolour, she completed a 4.2-km run in 51 minutes. Her steady pace and determination challenged stereotypes about ageing and physical limitation.
This story is done in collaboration with First Check, which is the health journalism vertical of DataLEADS.