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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.

Melissa Jefferson-Wooden delivered a sensational performance in Budapest, storming to victory in the women’s 100m at the inaugural World Athletics Ultimate Championship in a breathtaking 10.62 seconds.

The American produced a superb display of acceleration and composure to claim the World Ultimate Championship title while recording the fastest women’s 100m time in the world this year. Her 10.62 mark underlined her exceptional form and placed her firmly at the top of the global sprinting hierarchy.

Jefferson-Wooden controlled the race through the decisive stages and maintained her form all the way to the finish to secure a statement victory against a field packed with championship pedigree. She crossed the line ahead of Olympic champion Julien Alfred, who clocked 10.74 seconds with a -0.2 m/s wind, while Sha’Carri Richardson took third in 10.76.

Women’s 100m Final

1. Melissa Jefferson-Wooden — 10.62

2. Julien Alfred — 10.74 (-0.2 m/s)

3. Sha’Carri Richardson — 10.76

The victory was especially significant given the quality of the opposition. Jefferson-Wooden held her nerve against Alfred and Richardson, two of the most accomplished sprinters of the current generation, to produce the fastest performance in the world this year when it mattered most.

Alfred once again demonstrated her consistency at the highest level by taking silver, while Richardson completed an all-star podium in a race that brought together three of the biggest names in women’s sprinting.

But beyond the time, the title and the celebration, one of the most touching moments came after the race when Jefferson-Wooden embraced her father, Melvin, in an emotional celebration.

Their moment carried a deeply personal meaning. When Melissa was just 17 years old, she donated her stem cells to help her father undergo a bone marrow transplant after he was diagnosed with myelodysplastic syndrome. Years later, the two shared an unforgettable embrace in Budapest after she had become the World Ultimate Champion.

For Jefferson-Wooden, however, the evening was about far more than a medal. It was the culmination of an extraordinary journey, now highlighted by a world-leading 10.62 seconds on one of the biggest stages in athletics.

With the Ultimate Championship title secured and her father by her side, Jefferson-Wooden leaves Budapest with more than being an ultimate champion. She leaves with momentum, confidence and a powerful statement of intent — turning a high-profile showdown into one of the defining sprint performances of her season.

Audrey Werro has added another major title to her extraordinary season, storming to victory in the women’s 800m at the inaugural World Athletics Ultimate Championships in Budapest.

The Swiss star delivered a commanding performance, taking control from the opening gun and refusing to surrender the lead as she powered through an absorbing battle against two of the biggest names in the event.

Werro stopped the clock at 1:55.88 to become the Ultimate Championships 800m champion, producing another statement performance on one of the sport’s newest and most prestigious stages.

Behind her, Great Britain’s Keely Hodgkinson fought her way to second in 1:56.26, while the Netherlands’ Femke Broeders-Bol completed the podium in 1:56.74.

The result once again brought together the same formidable trio that featured on the podium at the European Championships, but Werro again proved to be the athlete who could rise above the challenge when it mattered most.

Her Budapest triumph is the latest chapter in a season that has already included records, a successful Diamond League Trophy defence and European Championship gold. Now, she can add the Ultimate Championships crown to a growing list of accomplishments.

Werro’s consistency has been particularly impressive in an 800m event packed with elite talent. Rather than simply relying on a fast finish, the Swiss athlete showed her authority by taking the initiative from the beginning and maintaining enough strength and composure to hold off Hodgkinson and Broeders-Bol all the way to the line.

The victory also underlined the remarkable depth of the women’s 800m, with three athletes separated by less than a second at the finish. Hodgkinson’s 1:56.26 and Broeders-Bol’s 1:56.74 showed just how fiercely contested the race was, but Werro’s decision to dictate the pace ultimately gave her the decisive advantage.

For Werro, this was more than another medal. It was another opportunity to demonstrate that her rise is no passing moment. On a stage featuring established champions and elite rivals, she once again produced the performance required to claim the biggest prize.

For Hodgkinson, the silver medal adds another major podium finish, while Broeders-Bol once again demonstrated her ability to compete with the very best over two laps.

But the spotlight in Budapest belonged unmistakably to Werro.

With another championship crown secured, the Swiss star has strengthened her claim as the athlete setting the standard in women’s 800m running. This is Audrey Werro’s era — and the rest of the field is chasing.

Busang Collen Kebinatshipi has delivered another sensational performance, storming to victory in the men’s 400m at the inaugural World Athletics Ultimate Championship in Budapest.

The reigning world champion stopped the clock at an astonishing 43.39 seconds, smashing his own Botswana national record and moving to fifth on the world all-time list.

Kebinatshipi produced a commanding finish to pull away from his rivals and secure the Ultimate Championship title. American star Rai Benjamin finished second in 44.15, while Jereem Richards of Trinidad and Tobago completed the podium in 44.23.

 Men’s 400m

1. Busang Collen Kebinatshipi — 43.39 NR

2. Rai Benjamin — 44.15

3. Jereem Richards — 44.23

The performance is even more remarkable considering that Kebinatshipi had already rewritten the Botswana record just one week ago in Brussels, where he ran 43.40. In Budapest, he lowered that mark by another 0.01 seconds to establish a new national record of 43.39.

That improvement has also propelled the 22-year-old into rare territory. His latest time now ranks him fifth fastest in history over 400m, placing him among an extraordinary group of athletes who have broken the 43.40 barrier.

Kebinatshipi's victory also caps an extraordinary season for the Botswana star. After establishing himself as a global champion, he has continued to demonstrate that he belongs among the very best one-lap runners in the world.

And there is a major reward for his historic night in Budapest: Kebinatshipi walks away as the Ultimate Champion and $150,000 richer.

From another national record to a place among the five fastest 400m runners ever, Kebinatshipi has turned an already remarkable season into something truly special.

Botswana has its latest sprinting superstar — and Kebinatshipi is showing that his ceiling may be even higher than anyone imagined. 

Marileidy Paulino once again proved why she is the undisputed queen of the one-lap event, powering to victory in the women’s 400m at the inaugural World Athletics Ultimate Championship in Budapest.

The Dominican Republic superstar produced a sensational 49.07 seconds to claim gold, pulling decisively away in the final straight and holding off a fiercely competitive field to extend her remarkable unbeaten run.

Paulino delivered her trademark combination of controlled speed and devastating finishing strength. She remained firmly in contention through the opening stages before unleashing her decisive move down the home straight, where she quickly opened a gap on her closest challengers.

Norway’s Henriette Jæger mounted a strong challenge but could not match Paulino’s finishing speed, crossing the line second in an impressive 49.28. Jamaica’s Nickisha Pryce completed the podium after clocking 49.56, ensuring that three of the world’s leading 400m talents occupied the medals.

The result once again underlined Paulino’s extraordinary consistency at the highest level. She entered Budapest as the world leader after running 48.48 in Paris in June, a performance that also set a Diamond League record. She subsequently remained unbeaten throughout her Diamond League campaign, closing the circuit with a meeting-record 48.64 in Brussels.

Budapest has also become a special venue in Paulino’s career. Three years ago, at the same National Athletics Centre, she captured her first individual world title, marking the beginning of another dominant chapter in her career. She later added Olympic gold in Paris in 2024, further establishing herself among the defining 400m athletes of her generation.

The inaugural World Athletics Ultimate Championship has brought together the sport’s biggest stars in a new winner-takes-the-spotlight format, with Olympic and world champions, Diamond League winners and leading performers competing for ultimate honours.

For Paulino, the occasion once again ended with Ultimate Crown on her arms.

With 49.07 seconds, she did more than win another major 400m title. She delivered another statement of authority, powering through the final straight with the confidence and speed that have made her one of the most dominant figures in modern women’s athletics.

Marileidy Paulino remains unbeaten, remains relentless and, once again, remains the queen of the one lap.

Jakob Ingebrigtsen has made a major decision regarding the remainder of his World Athletics Ultimate Championship campaign, confirming that he will withdraw from the men’s 1500m in Budapest despite producing a sensational performance to win the 5,000m title.

The Norwegian superstar stormed to victory in the inaugural Ultimate Championship 5,000m on Friday night, clocking a season-best 12:59.24 and delivering a devastating finishing kick to defeat Olympic 5,000m champion Cole Hocker and American Parker Wolfe.

Ingebrigtsen’s final 100 metres was arguably the defining moment of the race. The Olympic champion produced a remarkable 12.60-second closing 100m, powering away from the field to secure the $150,000 winner’s prize and underline just how far his fitness has progressed since returning from Achilles surgery.

The victory was particularly significant after what has been an extremely difficult period for the 25-year-old. Earlier in the season, Ingebrigtsen faced serious uncertainty over whether he would even be able to compete at the highest level again. His return has gradually gathered momentum, and his performance in Budapest offered perhaps the clearest indication yet that the Norwegian is rediscovering his formidable racing ability.

But rather than risk pushing his recovering body further, Ingebrigtsen has now opted to step away from the 1500m.

The decision means the highly anticipated showdown with British rival Josh Kerr will not take place in Budapest after all. The two stars had been expected to renew one of the biggest rivalries in modern middle-distance running in the 1500m final.

Instead, Ingebrigtsen is looking beyond the immediate opportunity and towards the bigger picture.

“I’m thinking about 2027… Fitness cannot be faked,” the Norwegian said, signalling that protecting his long-term condition has become more important than chasing another major victory only days after his return to peak-level competition.

The decision comes just one week after an emotionally charged Diamond League Final in Brussels, where Ingebrigtsen finished fourth in the 1500m behind Australia’s Cameron Myers, Kenya’s Phanuel Kipkosgei Koech and American Ethan Strand.

After that race, Ingebrigtsen delivered a fiery assessment of his rivals and questioned the tactics surrounding the pacemaking, particularly involving Hocker. He later acknowledged that there had been “a little too much adrenaline and emotion” when microphones were placed in front of him immediately after the race.

Yet his latest decision shows that beneath the emotion and competitive intensity lies a longer-term strategy.

Ingebrigtsen has already demonstrated that he can compete at an elite level again. His 12:59.24 in Budapest was not simply a victory — it was a statement that the Norwegian remains capable of producing a world-class finish even after months of injury rehabilitation.

Now, however, he is choosing not to gamble with that progress.

For a runner who has spent much of the year fighting his way back from injury, another 1500m race could have offered enormous rewards but also carried unnecessary risk. By withdrawing, Ingebrigtsen is effectively prioritising longevity over one more opportunity for immediate glory.

His message is clear: the comeback is underway, but it will not be rushed.

The 5,000m victory has given Ingebrigtsen confidence, momentum and perhaps, most importantly, proof that his body can once again handle elite competition.

Now comes the harder part — knowing when to stop.

With 2027 already firmly in his sights, the Norwegian has chosen recovery over risk. And after everything he has endured, that could ultimately prove to be one of the most important decisions of his comeback.

Jakob Ingebrigtsen is not walking away from the sport. He is protecting his future in it.