Running News Daily

I used to think running was a panacea. "If the furnace is hot enough, anything will burn, even Big Macs," as the fictional miler Quenton Cassidy once said. Then, about a decade ago, there was a big surge of doubt about the health effects of running. Most prominent was the suggestion that even modest amounts of running might damage your heart-"One Running Shoe in the Grave," as the Wall Street Journal put it-but running was also accused of broader sins like promoting inflammation, causing muscle loss, and wreaking havoc on blood sugar levels.

As a runner and a journalist, I spent a lot of time trying to understand these claims, and reevaluating my own understanding of running's health effects-a process that continues to this day. Part of that process involved going back to the original research that led us to believe that running is healthy. And to be honest, the evidence wasn't as clear as I'd assumed. Does running (or aerobic exercise more generally) really improve health markers, or is it just that healthy people are more likely to choose to run? Do the benefits max out after a few minutes per day, or do they keep growing? Can you outrun a bad diet?

I have opinions about all these questions, but I no longer assume that the answers are obvious. So I'm always interested in new data, like a recent study in PLoS ONE from the science team at InsideTracker, a company that sells personalized blood testing to track various health biomarkers. The paper offers a peek at the aggregated results of more than 23,000 customers who report various levels of running, divided into three groups: low volume (less than three hours of running per week), medium volume (three to ten hours per week), and high volume (more than ten hours per week). For comparison, they also include results from 4,400 sedentary non-runners, and at the opposite end of the spectrum, 82 professional distance runners.

There are two important caveats to point out before diving into the data. First, this is observational data, not a randomized trial. That makes it hard to determine whether running causes any of the patterns in the data (though, as we'll see below, there are some ways to test our assumptions about causation). Second, this is a self-selected cohort. Even the sedentary group is made up of people who are interested enough in their health that they've decided to spring for a service that starts at $699 for a single battery of blood tests. Since this control group is already fairly healthy, detecting any improvements will be more challenging.

The Raw Data

The journal article (which is free to read online) presents data on 27 different biomarkers that were significantly different between runners and non-runners. I'm just going to pick out a few categories that are particularly interesting.

First, here's HDL (i.e. "good") cholesterol levels, for females (f) and males (m) in each of the five groups: pro runners, high-, medium-, and low-volume amateurs (HVAM, MVAM, and LVAM, respectively), and sedentary people. 

The biggest difference is between runners and non-runners: runners have clearly higher levels, which is good. And among the runners, the trend is that more running is associated with higher levels. Similar patterns are seen for LDL ("bad") cholesterol and triglycerides: running is good, and more running is better.

Here are the fasting glucose (i.e. blood sugar) levels:

The pattern here is much less pronounced. There's still a significant difference between runners and non-runners, but the dose-response effect of more mileage is smaller in men and non-existent for women. The same is true when looking at HgbA1c levels, which offer an estimate of long-term average blood sugar levels rather than a single snapshot. In that case, there's a more pronounced difference between runners and non-runners, but no dose-response response effect. For blood sugar, then, running is good but more running isn't necessarily better.

One key point: the sedentary control group has remarkably good blood sugar levels, with an average below the prediabetes cutoff. Given that 98 million Americans have prediabetes, this confirms that the control group is already pretty healthy. If you were to compare runners to the average population, you'd probably see a bigger effect.

Another group of biomarkers is associated with chronic low-grade inflammation. The pattern here is a little more complicated, but data on C-reactive protein, white blood cell count, and ferritin collectively suggest that greater volumes of running are associated with lower levels of inflammation. The fact that ferritin is considered a marker of inflammation was a surprise to me, since I think of it as an indicator of iron levels in endurance athletes. But it turns out ferritin levels can mean different things in different contexts.

For most of the biomarkers, there's a fairly smooth trend from sedentary to pro runners. But there are a few examples where the pro runners are noticeably different from everyone else, even the amateurs who claim they're running more than ten hours a week. Most notably, the pro runners tended to have low magnesium levels-an observation that mirrors earlier data from British Olympic track athletes. The British study also found that athletes with a history of tendon problems were most likely to have low magnesium levels, which suggests that it's something to watch for if you're training hard.

Is It All About BMI?

All the results I mentioned above were statistically adjusted for body-mass index, age, and sex. That's important, because there were significant differences in BMI among the groups. Here's that data:

Now, I look at this graph and think, "Yep, all else being equal, the more you run the less you weigh." This used to strike me as a painfully obvious statement. The current scientific consensus, on the other hand, is that exercise is ineffective for weight loss. And it's true that lots of studies have assigned people to exercise, sometimes quite vigorously, and have seen underwhelming results for weight loss. This is a complex topic whose nuances I'll leave for another day, but suffice to say that the new data agrees with my feeling that, if you're running more than an hour a day, you very likely weigh less than you would if you weren't running.

You can get another level of insight by adding in some of the genetic data that InsideTracker also collects from some of its customers. There are a large number of separate gene variants that are associated with higher BMI; by checking which of these variants a given individual has, the researchers calculated a "polygenic risk score" for obesity. In the sedentary group, those with higher risk scores tended to have higher BMI. Among the high-volume and pro runners, in contrast, that trend was flattened: those with higher risk scores had similar BMI to those with lower scores. Though the sample size was too small to draw definitive conclusions (since relatively few customers opted to get genetic testing), the results suggest that running counteracted the gene variants associated with obesity.

The BMI data raises another important question: are all the other apparent health benefits of running just secondary effects of lower BMI? Here they use a cool technique called Mendelian randomization (which I wrote about in another context earlier this year). It's a way of turning a large observational study into a randomized trial. The randomization occurs at birth: as noted above, some people have gene variants that predispose them to have a higher BMI. These variants are randomly distributed, so if people with the low-BMI versions tend to also have better cholesterol scores (for example) regardless of whether or not they run, it suggests that BMI is what's driving the cholesterol scores.

The results of the Mendelian randomization-again limited by low sample numbers-are somewhere in the middle. It does appear that BMI explains much of the group's difference in cholesterol and inflammation levels, for example-but not all of it. For example, gene variants didn't predict LDL levels, suggesting that it's an independent effect of running.

But the closer you look, the blurrier the line between genes and behavior gets. Some of the genes associated with exercise are also associated with motivation and self-control; people who exercise a lot are also more highly motivated to eat healthily; and so on. We're back to the challenge I mentioned at the top: teasing out the independent health effects of going for a run is really hard. The InsideTracker researchers conclude that "a holistic wellness lifestyle approach is in practice the most likely to be most effective toward preventing cardiometabolic disease." That borders on tautological, but their data adds another small brick to the pile of evidence suggesting that endurance exercise, even or perhaps especially in large quantities, is a useful part of that holistic wellness lifestyle.

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.