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Consider two runners who, in lab testing, have identical values for VO2 max, running economy, and lactate threshold. These are the three quantities in the “standard model” of endurance performance; you can plug them into an equation to calculate your expected marathon time. So who will win the race?

The question is not as hypothetical as it seems. At the top end of the sport, athletes tend to have relatively similar values for all three of the parameters. And if they’re weak in one, they’ll compensate in the other two. And yet lab testing isn’t capable of reliably picking winners. The cyclist with the highest ever VO2 max flopped as a pro; the top marathoners that Nike picked for its Breaking2 marathon, including Eliud Kipchoge, didn’t have unusually high lab numbers. There’s clearly something missing from the equation.

Over the past few years, researchers have zeroed in on a suspect for what one paper calls “the fourth dimension” in the endurance equation. It has various names: durability, physiological resilience, fatigue resistance (which is the term I used when I first wrote about it in 2021). It’s a measure of how much your physiological parameters change over the course of a race. Maybe your VO2 max is 70 ml/kg/min at the start of the race, but has dropped to 65 ml/kg/min by the time you’ve run 20 miles. If your doppelgänger starts with the same values but still has a VO2 max of 67 ml/kg/min after 20 miles, he’ll beat you.

No one is entirely sure what determines fatigue resistance, which is why there’s currently a flurry of research into the topic. Two new papers fill in some gaps, suggesting that what you do before the race and what you do during the race can both have an impact.

The first study, published in the Scandinavian Journal of Medicine & Science in Sports by Runar Jakobsen Unhjem of Nord University in Norway, compares trained runners with “active adults.” The runners had been training for an average of about a decade, averaging a little over 40 miles a week with 10K bests of 33 minutes for men and 38 minutes for women. The active adults played recreational sports but did no more than two days a week of endurance training. Both groups completed a pair of VO2 max and running economy tests before and after an hour of running at a moderate pace corresponding to 70 percent of their individual VO2 max.

In both groups, VO2 max and running economy got worse after an hour of running—but the decline was much steeper in the active adults. Running economy is a measure of how much energy it takes to sustain a given pace; that energy cost increased four times more in the active adults than in the runners. VO2 max dropped by 5.0 percent in the active adults, but just 1.2 percent (not a statistically significant change) in the runners.

That means the active adults had to work harder to sustain the same pace, while at the same time their capacity to do that work was declining. Both groups started at 70 percent of their rested VO2 max, nominally working equally hard. But the figure below shows that by the end the active adults (AA) were pushing at well over 75 or their max while the trained runners (TR) were barely working harder at all:

The takeaway here is that fatigue resistance isn’t just something you’re born with, which is good news. It will improve with training–although what specific type of training targets it best remains to be determined.

The second study, published in the European Journal of Sport Science by a multinational research team led by James Spragg of the University of Cape Town in South Africa, looked at what types of in-race efforts cause the biggest changes in baseline values. Spragg was one of the authors of the study I wrote about back in 2021, which looked at fatigue resistance in professional cyclists after spending amounts of energy ranging between 1,000 and 3,000 kilojoules. But there’s a big difference between doing 3,000 kilojoules of work at a steady pace and doing it with surges and hill-climbs and so on.

The new study tested fatigue resistance in 14 professional cyclists after burning 2,000 kilojoules in two different ways. In one test, they stuck to steady low-intensity riding below their critical power. In the other test, they did 5 eight-minute intervals of hard riding above critical power plus enough easy riding to accumulate roughly the same amount of total work. Sure enough, the higher-intensity intervals produced a greater drop in their baseline physiological values, with the biggest effects on sprinting ability. The results suggest that, within a given run or ride, mid-race surges are what will deaden your finishing kick.

Based on the individual results, Spragg and his colleagues classify the cyclists as fatigue-resistant, semi-fatiguable, or fatigue-sensitive, with three, four, and seven of the riders, respectively, falling into these categories. Their previous research using real-world data from pro cyclists suggests that, all else being equal, fatigue-resistant riders are the ones who win races. So what determines who ends up in which category?

Other studies have linked poor fatigue resistance to inadequate fueling, but in this study all the riders took in 90 grams of carbohydrate per hour. There may also be metabolic differences in how different people use their internal stores of carbohydrate versus fat. The new data suggests that keeping your pace steady and avoiding unneeded surges might be advantageous. And as with the comparison between trained runners and active adults, training might be part of the answer. Previous data from pro cyclists did find that higher training volume was associated with greater fatigue resistance. In other words, we still haven’t figured out how to access the fourth dimension—but we’re finally getting some clues.

Jakob Ingebrigtsen brought his remarkable 2026 season to a fitting close on home soil, winning the men’s street 1500m at the inaugural Runfest Norway in Sandnes on Friday.

Competing in front of an enthusiastic hometown crowd, the Olympic and world champion took control of the race from the early stages and maintained his authority through the finish, stopping the clock at 3:40.7.

Andreas Fjeld Halvorsen followed in second in 3:43.3, while Sigurd Tveit completed the podium in 3:47.8.

The unusual street race added another dimension to the occasion, with 273 runners taking part on the same road and sharing the course with one of Norway’s most accomplished distance runners. For the recreational participants, it offered a rare opportunity to compete alongside Ingebrigtsen in an event that brought elite athletics and mass participation together.

The victory also provided a fitting final chapter to a season that began with significant uncertainty for Ingebrigtsen. After undergoing major Achilles surgery in February, the Norwegian was forced to miss a substantial portion of the summer campaign as he worked his way back to full fitness.

His return, however, quickly developed into another championship-winning chapter. In Birmingham, Ingebrigtsen captured European 5,000m gold before adding another major title at the inaugural World Athletics Ultimate Championship in Budapest, where he won the 5,000m.

Those performances transformed what could have been a disrupted season into another year defined by championship success and a determined return to the highest level.

Now, with the Sandnes victory added to his 2026 record, Ingebrigtsen closes the year exactly where it began in spirit — overcoming adversity, rebuilding his form and once again competing at the front.

From Achilles surgery in February to major championship victories and finally a 1500m win before his hometown crowd, the Norwegian has given his 2026 season a memorable final scene.

Olympic 100m hurdles champion Masai Russell has announced her engagement to longtime partner Robert “Robbie” Springfield, adding a major personal milestone to the remarkable journey of one of America’s leading track and field stars.

Russell shared the news with her followers, revealing that Springfield had proposed and that she had accepted. Reflecting on their relationship, the Olympic champion described him as her best friend and expressed her excitement about spending the rest of her life with him.

The couple’s relationship dates back to their college years at the University of Kentucky, where both were student-athletes and competed in track and field. Russell established herself as a standout hurdler, while Springfield competed in the long jump, giving them a shared understanding of the demands, sacrifices and pressures that come with pursuing success in athletics.

Springfield has since transitioned from competition into coaching. A former collegiate long jumper, he is now part of the coaching staff at Morehead State University, where he works with the programme’s sprinters and jumpers.

Their relationship has developed alongside Russell’s rise to the top of the sport. The defining moment of her career came at the Paris 2024 Olympic Games, where she captured gold in the women’s 100m hurdles, securing her place among the sport’s Olympic champions.

Away from competition, Springfield has remained a familiar part of Russell’s journey, sharing in the demanding periods of training and competition that accompanied her pursuit of Olympic success. Their connection has consequently grown from a college athletics relationship into a long-term partnership.

The engagement now marks another significant chapter for Russell, this time away from the track. After reaching the pinnacle of her sporting career in Paris, the 100m hurdles champion is beginning a new phase of her personal life alongside a partner who has been part of her journey since their university days.

From competing on the same collegiate stage to building a future together, Russell and Springfield’s story has evolved alongside two careers shaped by track and field. The Olympic champion will now balance this new personal chapter with her continuing ambitions in athletics

The women’s race at the 2026 TCS Amsterdam Marathon is shaping up to be one of the most competitive editions in recent years, with a deep international field set to take on the fast Dutch course on Sunday, October 18.

At the centre of the contest will be four Ethiopian athletes who have already broken the 2:20 barrier, creating the prospect of a fascinating battle for victory and a possible assault on the course record of 2:16:52.

Defending champion Aynalem Desta will return to Amsterdam looking to retain her title after producing the biggest performance of her career at last year’s 50th edition. Desta won in a personal best of 2:17:37, establishing herself among the leading marathoners in the field and setting the benchmark for this year’s contenders.

Standing in her way will be fellow Ethiopian Meseret Belete Tola, a former Amsterdam champion who knows exactly what it takes to succeed on the course. Belete Tola captured the 2023 edition in 2:18:21, and her return adds another layer of experience and proven quality to an already formidable lineup.

The field also includes Mestawut Fikir Truneh, who arrives with an impressive marathon pedigree. Truneh finished runner-up at the 2024 Berlin Marathon in 2:18:48, demonstrating her ability to compete at the highest level on one of the world's major marathon stages.

Completing the quartet of sub-2:20 Ethiopians is Buze Diriba, whose personal best of 2:19:34 places her firmly among the leading contenders. With four athletes possessing credentials below 2:20, the race is likely to develop into a tightly contested battle from the opening kilometres.

The depth extends well beyond the leading quartet. Desi Jisa Mokonin, representing Bahrain, Yeshi Kalayu Chekole of Ethiopia and Nazret Weldu Gebrehiwet of Eritrea have all established themselves as serious marathon competitors with performances approaching the 2:20 mark.

Another major name to watch is Abeba Aregawi, the former 1500m world champion representing Sweden. Aregawi has successfully transferred her talents to the marathon and made headlines earlier this year by setting a Swedish national record of 2:23:12 on her debut. Her presence adds another intriguing dimension to an already high-quality field.

Amsterdam’s marathon course has consistently provided an opportunity for elite athletes to produce fast times, and this year’s women’s lineup has the depth to turn the race into a genuine test of both championship racing and outright speed.

With four athletes already inside 2:20, two former Amsterdam champions returning to the start line and several other accomplished marathoners ready to challenge them, the battle is expected to remain open deep into the race.

The ultimate target will be the Amsterdam women’s course record of 2:16:52. Whether the leading contenders can threaten that mark remains to be seen, but the quality assembled for October 18 ensures that the record will be firmly in the spotlight when the race reaches its spectacular finish inside the Olympic Stadium.

The 2026 Valencia Half Marathon is shaping up to be a thrilling contest of speed, endurance and tactical brilliance, with some of the world’s finest road runners set to converge in Spain on October 25.

Kenya’s Daniel Ebenyo and Alex Matata will be among the leading contenders, facing a formidable Ethiopian challenge spearheaded by Jemal Yimer and Tadese Worku. The field also features Rodrigue Kwizera, who boasts the fastest personal best among the leading entrants at 58:16.

Ebenyo arrives with a personal best of 59:04, placing him firmly among the athletes capable of sustaining a demanding pace over the 21.1-kilometre distance. Matata, who owns a 59:11 best, adds further Kenyan strength, while Andrea Kiptoo brings another sub-60-minute credential to the race.

Yimer has already established himself as one of the fastest athletes in the field with a 58:33 personal best, while Worku has clocked 58:35. Kenya’s Owen Korir, with a best of 58:58, further underlines the remarkable depth of the men's lineup.

Valencia Half Marathon 2026 Entries

1. Rodrigue Kwizera (Spain) — 58:16

2. Jemal Yimer (Ethiopia) — 58:33

3. Tadese Worku (Ethiopia) — 58:35

4. Owen Korir (Kenya) — 58:58

5. Daniel Ebenyo (Kenya) — 59:04

6. Alex Matata (Kenya) — 59:11

7. Andrea Kiptoo (Kenya) — 59:11

8. Thierry Ndikumwenayo (Spain) — 59:42

9. Said Mechaal (Spain) — 1:00:24

10. Adel Mechaal (Spain) — 1:02:30

Kwizera, who finished second in Valencia last year, leads the field on paper and will be seeking another standout performance on the famously fast Valencia course. With several athletes carrying sub-60-minute credentials, the race has the ingredients for an aggressive battle from the opening kilometres.

Beyond the headline names, the men’s field is deep and highly competitive, bringing together a strong collection of experienced international athletes with proven ability over the half-marathon distance. With so much quality packed into the lineup, the race promises an intriguing battle in which tactics, endurance, positioning and finishing speed could all play a crucial role in determining the eventual champion.

Yet personal bests will count for little once the gun goes off. The title could ultimately be decided by patience, positioning and the ability to respond when the pace begins to rise in the closing stages. Every surge, every tactical move and every second saved could prove decisive on the road to the finish.

With Kenya, Ethiopia and Spain represented by athletes of exceptional quality, Valencia promises a high-octane men's showdown in which the leaders are likely to be separated by only a handful of seconds. The final kilometres could provide the defining moments of a race packed with speed, ambition and anticipation.

On October 25, the question will be simple: who has the strength to command the streets of Valencia and claim the coveted half-marathon crown?

April 19, 1982. The Boston Marathon unfolded under unusually warm, sunny conditions, and by the closing stages, the race had become a private battle between two very different American runners: Alberto Salazar, already one of the biggest names in distance running, and Dick Beardsley, the Minnesota runner who had emerged as a serious marathon contender.

For roughly nine miles, from the Newton Hills toward the finish, Beardsley did much of the leading, with Salazar tucked close behind. Neither man could shake the other. They ran deep into Boston locked together, trading surges and refusing to surrender an inch as the crowds along the course grew louder.

Salazar finally made his decisive move with less than a mile remaining. He opened a small gap, but Beardsley refused to disappear. The Minnesota runner chased him through the final streets, closing again as they approached the finish.

Then came the final sprint.

Salazar held his form and reached the finish first in 2:08:52, with Beardsley only two seconds behind in 2:08:54. It was an extraordinary result: both men broke 2:09 in the same Boston Marathon, and both shattered the previous course record.

The race became known as the “Duel in the Sun,” and it remains one of the most celebrated head-to-head battles in Boston Marathon history. Beardsley had not won, but his performance established him as one of America's elite marathoners.

For Salazar, however, victory came at an enormous physical cost. Immediately after crossing the finish line, he collapsed and required emergency treatment, including several litres of intravenous saline. The combination of heat, dehydration and an all-out effort had pushed his body to the limit.

Salazar's marathon career would never again produce quite the same kind of performance. His celebrated 1981 New York City Marathon victory had produced what was initially considered a world record, although the course was later found to be short. His Boston triumph therefore became one of the defining victories of his career.

Beardsley's story would take an even more difficult turn. Injuries disrupted his career, and after returning to the highest level, he suffered a devastating farm accident in 1989. Further accidents, surgeries and severe physical pain followed, eventually leading to a long battle with painkiller addiction.

He eventually overcame that struggle and transformed the darkest chapters of his life into a story of recovery, resilience and redemption.

That is what makes the 1982 Boston Marathon more than a two-second victory.

For one extraordinary afternoon, Salazar and Beardsley produced a marathon duel in which neither man was willing to give way. One crossed the finish line first. The other finished only two seconds behind him.

Two seconds separated them at Boston. Decades later, their legendary duel remains one of the greatest chapters in marathon history.