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Over the past century, “maximal oxygen uptake” has turned out to be a valuable marker of both endurance and health.No tidbit of physiological jargon has achieved more popular renown than VO2 max, also known as maximal oxygen uptake. And, for the past century, none has been so consistently misunderstood. A new commentary in the International Journal of Sports Physiology and Performance, led by Grégoire Millet of the University of Lausanne, marks the 100th anniversary of the landmark paper by A. V. Hill and Hartley Lupton that first described VO2 max. It’s a big milestone, and it offers a good excuse to take a closer look at what VO2 max really means and why it (sometimes) matters.

A.V. Hill was a 4:45 miler and already had a Nobel Prize for work in muscle physiology when he and Lupton began studying VO2 max. The experiments involved subjects running around Hill’s back garden in Manchester with air bags strapped to their back to measure how much oxygen they used. The faster they ran, the more oxygen they needed—but only up to a certain point. Eventually, oxygen consumption plateaued, even as they continued to accelerate.

Beyond this plateau—what’s now known as VO2 max, indicating the maximum volume per unit time of oxygen (O2)—they had to rely on anaerobic energy pathways, going into what Hill called “oxygen debt.” This debt couldn’t be sustained for long thanks to rising lactic acid, which meant that VO2 max effectively marked the limits of sustainable effort. In other words, VO2 max was an objective measure of endurance.

The current understanding of exercise metabolism has evolved in a few respects since Hill’s time. Physiologists no longer talk about oxygen debt, and lactate (not lactic acid) is considered a marker of fatigue but not its direct cause. But the basic idea remains the same: there’s a limit to the rate at which your body can take in and use oxygen, and having a higher limit augurs well for both performance and health.

The initial understanding of VO2 max was that it was a measure of cardiovascular function, limited primarily by how rapidly your heart could pump oxygen-rich blood to your muscles. For elite endurance athletes, that’s still a pretty good approximation: aerobic monsters are distinguished primarily by a large and compliant heart that can pump huge volumes of blood with each stroke.

But over time, researchers realized that the limits of oxygen uptake are best thought of as a cascade with numerous steps. You have to inhale oxygen into your lungs, diffuse it into your bloodstream, pump it to your muscles, diffuse it into your muscles, and then your mitochondria have to use it to generate ATP. Each of those steps can become a limiting bottleneck in certain conditions, so there isn’t one single path to altering VO2 max.

There are two ways of quantifying your VO2 max. The absolute value is expressed in liters of oxygen per minute: a well-trained endurance athlete, for example, might be able to consume 5 L/min of oxygen. The relative value, which is the more commonly discussed number, is simply the absolute value divided by your weight in kilograms. If that same endurance athlete weighed 70 kilograms, their relative VO2 max would be 71 ml/min/kg.

The standard method of measuring VO2 max, originally developed as an offshoot of the infamous Minnesota Starvation Study during World War II, is a treadmill test (or the equivalent with some other form of exercise like a stationary bike), lasting six to 12 minutes and getting progressively harder in stages until you max out. But what does it mean to max out? There are various criteria: oxygen consumption reaching a plateau, heart rate reaching a plateau, lactate levels exceeding 8.0 mmol/L, perceived exertion greater than 17 on a scale of 6 to 20, respiratory exchange ratio (a comparison of much carbon dioxide you exhale compared to how much oxygen you’re consuming) of greater than 1.1.

The reason for all these criteria is that the idealized picture of a steady increase in oxygen consumption followed by a plateau often doesn’t show up in real life. And even when it does, it’s not an invariant number: your VO2 max when kayaking will be smaller than when you’re running, for example, because you’re using smaller muscles that can’t gobble up as much oxygen. (That’s why rowers tend to have some of the highest absolute VO2 max values, because they’re huge and they’re using both arm and leg muscles. Cross-country skiers have some of the highest relative values, because they’re also using arms and legs but are generally much lighter than rowers.)

There are even a few studies that have found different VO2 max values depending on the details of the treadmill protocol. How can it be the ultimate objective measure of endurance if its value depends on how you test it? Is the apparent plateau just your brain deciding that you’ve had enough and should step off the treadmill? These and other controversies persist. My take: the VO2 max plateau is real and dictated by physiology, but it’s not as clear-cut a threshold as once thought.

If you tested all the runners on the start line of an Olympic distance race, their VO2 max values wouldn’t tell you much about how they’d place. They all have high values, and the race won’t necessarily be won by the runner with the highest value. Eliud Kipchoge, for example, reportedly has a relatively unexceptional value for an elite marathoner. In that sense, VO2 max isn’t a great predictor of running performance. And the cyclist with the highest ever reported VO2 max, Oskar Svendsen, didn’t end up setting the world alight, as I recounted a few years ago.

On the other hand, if I had to predict the race finishing order of 100 people randomly picked from the street, and I was allowed one physiological test, I’d opt for VO2 max. In that diverse population, VO2 max values would be all over the map, and those with the highest values would likely finish at or near the front. So in that sense, VO2 max is a great predictor. To put it another way, a high VO2 max is a necessary but not sufficient condition for endurance success. It’s your ticket into the game.

You could argue that VO2 max has greater value as a predictor of health and longevity than of athletic success. While the relationship between exercise habits and longevity remains a little hazy, with some people arguing that too much is bad for you, the link between VO2 max and longevity is unambiguous: higher is better. In fact, the American Heart Association has argued the VO2 max should be considered a “vital sign” and be regularly measured or estimated by doctors.

Back in the 1990s, the Heritage Family Study trained about 500 people from 100 different families for 20 weeks. On average, they were able to boost their VO2 max by about 20 percent. But they saw a wide range in responses: some people saw more than twice as big an increase, while others basically didn’t increase at all. And that variation seemed to cluster within families. The researchers estimated that about half the VO2 max training response was dictated by genetics.

The idea that some people don’t improve their VO2 max at all even with regular training remains controversial. A few different studies have taken aim at this idea, and shown that if you take non-responders from a study and have them either train more or train harder, everyone will eventually respond. Still, it’s clear that some people can increase their VO2 max more easily than others.

Trained athletes eventually hit a point of diminishing returns, although long-term structural adaptations like the size of your heart and the density of capillaries distributing blood can continue to improve. A meta-analysis a decade ago found that interval training can produce substantial improvements, with the biggest bang from intervals lasting three to five minutes per rep. The highest recorded values tend to be around 90 ml/kg/min in men and 80 ml/kg/min in women, with the sex differences attributable to higher body fat and lower hemoglobin levels in women.

As important as increasing your VO2 max is, the bigger challenge for many of us is slowing its decline. After age 25, it typically drops about ten percent a decade. According to a recent analysis, athletes who keep training can slow that decline to about 5 percent a decade, but those who fall off the wagon might see even steeper declines.

Overall, Millet and his colleagues conclude that VO2 max is “a healthy and active centenarian” that remains important in both endurance sports and as a measure of cardiovascular health. It’s not the ultimate barometer of fitness, but neither is it a meaningless detail. If you get a chance to have yours tested, for example by volunteering for a study at a local university, I highly recommend it. It can be fun to learn about your own physiology—and, during the final stage of the test where you keep pushing until you’re on the verge of being thrown off the back of the treadmill, your psychology.

Ethiopia’s Fotyеn Tesfay Haylu delivered one of the most remarkable women’s half-marathon performances ever seen on American soil on Sunday, powering to a commanding victory at the 2026 Buenos Aires Half Marathon in Argentina in 1:03:57.

Running with exceptional confidence and strength, Tesfay took control of the race and produced a superb solo performance to rewrite the event record. Her breathtaking run also carried historic significance, as she became the first woman to break the 64-minute barrier for the half marathon in the Americas, producing what is being celebrated as the fastest women’s half-marathon performance ever recorded on the continent.

The Ethiopian star was in a class of her own, crossing the finish line more than a minute clear of Turkey’s Nevin Can, who finished second in 1:05:06. Another Turkish athlete, Selin Can, completed the podium in third place with 1:05:11, as the leading trio all produced strong performances on the fast streets of Buenos Aires.

Kenya also featured prominently in the top positions, with Irene Jepchumba Kimais taking fourth in 1:06:04, followed by Sheila Chepkirui in fifth with 1:06:13. Magaret Akidor Ngathike finished sixth in 1:06:46, while fellow Kenyan Deborah Samum claimed seventh place in 1:08:32.

Brazil’s Nubia de Oliveira Silva was eighth in 1:11:13, while Argentina’s Sofia Luna and Dahyana Juarez rounded out the top 10 with times of 1:11:21 and 1:11:28, respectively.

Top 10 Women – 2026 Buenos Aires Half Marathon

1. Fotyеn Tesfay Haylu (Ethiopia) – 1:03:57

2. Nevin Can (Turkey) – 1:05:06

3. Selin Can (Turkey) – 1:05:11

4. Irene Jepchumba Kimais (Kenya) – 1:06:04

5. Sheila Chepkirui (Kenya) – 1:06:13

6. Magaret Akidor Ngathike (Kenya) – 1:06:46

7. Deborah Samum (Kenya) – 1:08:32

8. Nubia de Oliveira Silva (Brazil) – 1:11:13

9. Sofia Luna (Argentina) – 1:11:21

10. Dahyana Juarez (Argentina) – 1:11:28

For Tesfay, it was far more than a race victory. Her 1:03:57 performance was a statement of extraordinary quality, combining speed, endurance and remarkable solo running to produce a landmark result in Buenos Aires. In a race that will be remembered for years to come, the Ethiopian did not simply win—she redefined what was thought possible for women’s half-marathon running in the Americas.

Ethiopia’s Yomif Kejelcha produced one of the most extraordinary performances in road racing history on the streets of Buenos Aires, Argentina, reclaiming the half marathon world record with a sensational 56:51 performance at the 2026 Buenos Aires Half Marathon.

The former world record-holder delivered a breathtaking exhibition of speed and endurance to take 29 seconds off the previous pending mark of 57:20, set by Uganda’s Jacob Kiplimo and takes a huge chunk from his own former official world record. Kejelcha's new performance is pending the standard ratification procedures, but if officially ratified, it will return the world record to the Ethiopian star and mark another remarkable chapter in the evolution of the event. 

Kejelcha's achievement is particularly significant because the 57-minute barrier had already been broken before. Jacob Kiplimo had previously run under 57 minutes, clocking 56:42 that was not ratified demonstrating that the once-unthinkable barrier was possible. Kejelcha, however, has become the second man to run under 57-minute barrier who now returns to the top of the all-time rankings with another historic performance in Buenos Aires.

The Ethiopian's race was remarkable not only for the final time but also for the way he built his performance. He covered the opening five kilometres in 13:44 before reaching 10km in 27:18. Rather than slowing, Kejelcha accelerated through the middle stages, passing 15km in 40:39 and 20km in 54:02 as he continued to push the limits of elite road racing.

By the time he reached the finish line, Kejelcha had completed the race at an extraordinary average pace of approximately 2:42 per kilometre, producing one of the most astonishing sustained efforts ever witnessed in distance running. His stunning run sent a powerful message to the athletics world and further strengthened his status as one of the most formidable distance runners of his generation.

Behind the record-breaking champion, Ethiopia completed a dominant clean sweep of the men's podium. Tadese Worku Gebresilase claimed second place in 59:18, while Bereket Nega Batebo secured third in 1:00:17, giving Ethiopia a memorable one-two-three finish in the Argentine capital.

Kenya’s Jonathan Kipkoech Kamosong finished fourth in 1:00:20, followed by compatriot Simon Maywa in fifth with 1:00:55. Argentina’s Ignacio Erario gave the home supporters plenty to celebrate with an impressive sixth-place finish in 1:00:57, breaking the one-hour barrier in front of an enthusiastic local crowd.

Dillon Kipyeko of Kenya finished seventh in 1:01:07, with Robert Kiprop Koech eighth in 1:02:01. Mexico’s Julio Ortiz Ponce took ninth place in 1:03:17, while Colombia’s Jimmy Gómez completed the top 10 in 1:03:34.

The Buenos Aires Half Marathon will now take its place in the history books as the scene of a truly extraordinary breakthrough. For Kejelcha, this was more than just another victory. It was a spectacular return to the top, reclaiming a world record he had previously held and once again rewriting the limits of the half marathon.

The 56:51 performance remains pending ratification, but Yomif Kejelcha's run has already delivered one of the defining moments in the history of road racing.

Kenya delivered another commanding display of distance-running excellence at the Antrim Coast Half Marathon, with Isaia Lasoi leading a memorable Kenyan clean sweep of the men's podium in a race packed with world-class performances.

Lasoi emerged victorious after a thrilling battle at the front, crossing the finish line in a superb 58:26 setting a new course record. His winning performance underlined his strength and speed over the half-marathon distance, but he was made to work all the way by fellow Kenyan Daniel Mateiko, who finished just three seconds behind in 58:29 after an electrifying duel for the title.

The contest between the two leaders produced one of the standout moments of the race, with both athletes pushing deep into elite territory as they fought for victory. In the end, Lasoi found just enough to secure the win, while Mateiko's narrow defeat highlighted the remarkable depth and quality of Kenya's leading distance runners.

Vincent Kipkorir completed the Kenyan sweep, taking third place in 1:00:38 to ensure that all three places on the podium belonged to Kenyan athletes. Samwel Chebolei added further Kenyan strength to the results, finishing fourth in 1:01:01, while Amos Langat was also among the leading finishers.

The international field featured several prominent names. Australia's Jimmy Whelan produced a strong run, while Ethiopia's Yismaw Dillu featured among the front group. American marathon star Galen Rupp also delivered a notable performance, clocking 1:01:29 in another competitive outing for the experienced distance runner. Former world-class track and road athlete Edward Cheserek was also among the top finishers.

Lasoi's 58:26 victory, however, was the defining performance of the day. Together with Mateiko and Kipkorir, he gave Kenya a perfect podium and another emphatic reminder of the country's extraordinary strength in elite road running.

The Antrim Coast Half Marathon once again provided a fast, competitive stage for some of the world's finest distance runners, but when the decisive moments arrived, it was Kenya that owned the podium.

One of the most iconic milestones in the history of ultramarathon running is drawing closer, with entries for the historic 100th edition of the Comrades Marathon set to open on Tuesday, 25 August 2026.

The Comrades Marathon Association has officially announced a detailed entry process for the 2027 race, which will unfold in three stages and give runners around the world the opportunity to secure their place in what promises to be one of the most significant editions ever held of The Ultimate Human Race.

The announcement followed the official launch of the 2027 Comrades Marathon on Wednesday, 19 August, when the centenary campaign, “The Greatest Story Ever Run,” was unveiled alongside a special logo created exclusively for the landmark 100th edition.

The launch also revealed several major highlights for the Centenary Race. The historic event will take place on Sunday, 13 June 2027, and will be a Down Run, with 28,000 places available. The entry process will include a ballot, while the race will offer a record R8.919 million in prize money. Organisers have also set an ambitious goal of raising R10 million for the Amabeadibeadi charities, adding an important charitable dimension to the centenary celebrations. One of the defining moments of the launch was the unveiling of the special Centenary mark, created to commemorate this extraordinary milestone in the history of the race.

The entry process begins on 25 August at 10:00 a.m. SAST, when entries open for Green Number runners, Yellow Number runners and Amabeadibeadi charity entrants.

The next phase follows on 2 September at 10:00 a.m. SAST, when entries open for Comrades Marathon Association members. This window will remain open for 72 hours or until the available entry allocation is filled, with places offered on a strictly first-come, first-served basis.

For general entrants, the process will move to a ballot system. General entries open on 9 September at 10:00 a.m. SAST, with runners able to enter the ballot until it closes on 22 September at 4:30 p.m. SAST. The ballot draw is then scheduled to take place on 23 September.

Several other crucial dates will shape the road to the historic race. The substitution period will run from 15 to 31 March 2027, while 3 May 2027 is the final deadline for runners to submit their qualifying performances, seeding information and other required entry details.

To qualify for the 2027 Comrades Marathon, runners must complete a 42.2km marathon in under five hours between 15 June 2026 and 3 May 2027.

The journey will finally culminate on Sunday, 13 June 2027, when thousands of runners are expected to line up for the historic 100th edition of the Comrades Marathon.

The 2027 race will represent a remarkable moment for the legendary South African ultramarathon. For more than a century, the Comrades Marathon has captured the imagination of runners and spectators with its extraordinary test of endurance, determination and human spirit. Its centenary edition will celebrate the generations of athletes who have faced its demanding roads, conquered its challenges and helped build one of the world's most respected endurance events.

For runners dreaming of becoming part of this historic occasion, the road to Comrades 2027 is now clearly marked. From the opening of entries in August 2026 to race day in June 2027, every deadline will matter.

The Greatest Story Ever Run is preparing for its most historic chapter yet.

American sprint standout Sam Blaskowski is taking steps toward an international future with Poland after uncovering a powerful connection to his family's ancestral homeland.

The 23-year-old sprinter, who has established himself as one of the fastest Americans of his generation with a personal best of 9.89 seconds in the 100 metres, has begun the process of obtaining Polish citizenship with the aim of eventually representing Poland in international competition.

Blaskowski's connection to the country traces back through his great-grandparents, Franciszek and Julian Błaszkowski, who emigrated from Poland to the United States in 1905. Their journey more than a century ago has now opened an unexpected new chapter for their descendant, whose athletic ambitions could soon carry the Błaszkowski name back onto the international stage under Polish colours.

The sprinter has already received support from the Polish Athletics Association as he works through the citizenship and eligibility process. Should his transfer of allegiance be completed, Blaskowski could become a significant addition to Poland's sprint programme.

His credentials certainly make the prospect an exciting one. In addition to his sub-10-second speed over 100 metres, Blaskowski owns a personal best of 19.93 seconds in the 200 metres, demonstrating the kind of versatility that could prove valuable both individually and in Poland's 4x100m relay squad.

For Blaskowski, however, the move is about more than simply changing national colours. It represents an opportunity to reconnect with his family's heritage while pursuing his ambitions at the highest level of the sport.

With his sights set on becoming part of Poland's international sprint team and competing for relay medals, Blaskowski's journey from discovering his Polish roots to potentially representing the country of his ancestors could become one of the most fascinating allegiance stories in world athletics.

A century after Franciszek and Julian Błaszkowski left Poland for America, their family's story may now be coming full circle—this time at full sprint.