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Hemoglobin is measured in every blood panel, a major determinant of athletic potential staring us right in the face.

Hemoglobin is a protein in red blood cells that carries oxygen to working muscles. It's a load-bearing pillar of athletic performance and aerobic development, influenced by genetics, iron levels, training history, altitude, and stress. Hemoglobin is so important that endurance sports have faced existential crises from athletes trying to hijack their physiologies through illegal, immoral performance-enhancing drugs like EPO, which stimulates red blood cell production and increases hemoglobin levels. 

A disturbing 2013 study in the PLOS One journal found that 4 weeks of EPO injections increased hemoglobin mass by 19.7%, which corresponded to a 6% improvement in 3k time trials with no training changes. That study was funded by the World Anti-Doping Association, which seems similar to the DARE program conducting a study on whether or not heroin feels good. Interestingly, that study also tried to optimize for iron levels to improve hemoglobin mass increases, having athletes take 100 mg of elemental iron a day (550% of the recommended daily value). Unethical, arguably evil use of EPO and blood doping has risked ruining Olympic endurance sports over the last 30 years, and it all gets back to that simple biomarker. Increased hemoglobin mass improves oxygen transport during exercise and thus has a profound impact on performance.

Cheating to raise hemoglobin mass is both vile and dangerous. But what if I told you that there are healthy, legal interventions that can improve hemoglobin mass? You can tell they are healthy because they often correspond with reduced stress and improved cardiovascular function-think optimizing iron intake, balancing stress, and living at altitude. You can tell they are legal because the interventions work over longer time horizons and only budge hemoglobin mass by a couple percent at most. It's the difference between feeling good after eating a serving of dark chocolate versus feeling good after snorting a bunch of cocaine. 

New Study on Heat Exposure and Hemoglobin Mass

A 2022 study in the Scandinavian Journal of Medicine and Science in Sports asked a fascinating question: how does heat training via heat suits affect hemoglobin mass in elite athletes? To evaluate the question, the study split 25 elite cross-country skiers into a heat group and a control group that were matched for intensity and duration of training. We're not just talking normal athletes, but national and international competitors at the pointy end of human performance. So any changes in hematological variables would be coming on top of relatively optimized physiologies.

Participants in both groups completed normal training in the AM. In the PM, the heat group did 50 minutes of low-intensity indoor cycling on a stationary bike 5 times a week for the 5-week intervention. But there was a very hot twist. They were wearing a "wool layer on both the upper and lower body, a wool hat, nylon rain jacket, down jacket, and nylon pants with poor evaporative capacity." While they followed the study instructions well, they fully ignored Nelly's instructions, because it got hot in there and they put on all their clothes. We need a follow-up study to test whether they do, in fact, want scrubs.

Despite the added double sessions in the heat, there was no difference between the groups in training duration or intensity across the 5 weeks. Now is the time when we take a step back to hypothesize what we think happens next. The participants' baseline attributes are relevant to your guesses. The heat group had a starting point hemoglobin of 16.1 g/dl and hematocrit of 45.7%, already very high (likely due to some combination of training and genetics). For comparison, in that dastardly EPO study, the end point for hemoglobin levels was 15.2 g/dl even after the 20% increase from undergoing the Armstrong protocol. Moving a pebble with a bulldozer is one thing. But this study was looking at moving a boulder with a finger flick. Could a flick of heat exposure with low-intensity training move that boulder?

The answer: a resounding yes. The boulder didn't move far, but it left an unmistakable trail, kind of like one of those mysterious moving rocks in Death Valley. And any movement of hematological variables through healthy means at this elite level of performance is a BIG FREAKING DEAL. 

Relative to the control group, the heat group's hematocrit increased by 1.58% and hemoglobin mass increased by 30 grams. While there was no change in the performance metrics tested, those blood changes should have beneficial impacts on performance and recovery over longer time horizons. 

So, Should I Just Hit the Sauna?

Here is where things get complicated, interesting, and frankly, a bit annoying. A 1997 study in the International Journal of Sports Medicine found no hemoglobin mass changes with 4 weeks of training in hot environments between 19 C and 32 C, with numerous studies over the years showing small or negligible changes. That is contrasted by a 2022 study in Medicine and Science in Sports and Exercise that found 2.4-2.6% increases in hemoglobin mass from training in a heat suit or heat chamber (see also this 2020 study in the journal Experimental Physiology and this 2019 study in Frontiers of Physiology showing hemoglobin mass increases from heat acclimation protocols). And now is where we have to start questioning the exact mechanism at play, which will help determine how you put these findings into practice.

One theory is that with heat exposure, the body increases plasma volume (the liquid content in the blood), reducing hematocrit (the percentage of red blood cells within a blood sample) through dilution. As the kidneys sense an offset, the body increases natural EPO production to raise hematocrit levels to baseline, but with a higher denominator from the increased plasma volume, thus increasing the numerator: red blood cells and total hemoglobin mass. In that formulation, even after the plasma volume goes down later, the body will be left with more hemoglobin mass to play with.

If the driver is just the plasma volume-hematocrit-hemoglobin mass pathway (for more, the "critmeter" theory is outlined in this 2003 conference paper), it shouldn't take heat suits or heat chambers to spur the adaptations. We should have seen them in the 1997 study, or other studies finding increased plasma volume from training interventions. Maybe it doesn't have to just be kinda hot, it needs to be REALLY hot. As the authors of the main 2022 study, we are looking at say: "The rate of EPO synthesis is mainly regulated by the hypoxiainducible factor (HIF) system, which, however, also has been shown to stabilize with increased heat shock protein expression." (Check out this 2005 research article in Physiological Genomics to go deep on the subject.) Heat shock proteins that incite the HIF system may require higher temperatures than normal training in warm ambient air.

Context and Implications of Heat Training

And that's just the tip of the iceberg (the hotberg?). A recent study on the topic of natural EPO synthesis made me concerned, and it has nothing to do with heat at all. Published online in November 2022 in the American Journal of Physiology, Endocrinology, and Metabolism, it found that post-exercise ingestion of exogenous ketones increased natural EPO production by 20% over a control group. While the mechanism is uncertain, it's possible that post-exercise ketones incite the HIF system, which may be part of the reason why it's reported that more than 60% of the Tour de France peloton takes them. 

I'm bringing up that preliminary study on ketones to illustrate why I'm such a proponent of heat for athletes probing the margins of performance physiology: studies seem to indicate that it's a natural, healthy way to increase hemoglobin mass and improve performance without probing the gray areas of what else incites the HIF system. Heat exposure has been practiced by some cultures for centuries, with plenty of positive impacts that have nothing to do with endurance performance (though based on the recent success of sauna-loving Norwegians, maybe there's a connection there too). 

There are tons of unanswered questions that will be addressed by future studies. How do these adaptations unfold over longer time horizons, as plasma volume stabilizes? Will it work with passive heat exposure, like the sauna or a hot bath? Could it be counterproductive in athletes with limitations on hemoglobin production, like those with low iron stores or naturally low genetic setpoints? Would it be less effective at altitude? Could there be hormonal impacts that reduce the efficacy over time, or prevent it from working in female athletes at all? That last question is the biggest, since all of the studies I have seen do not include female participants, likely because the menstrual cycle causes blood volume fluctuations beyond those seen from the interventions. 

Conclusion: So, How Much Heat Training Do I Need?

The longer I coach, the more I support year-round heat exposure because these study findings seem to be backed up in the training data for athletes Megan and I coach, even for performance in temperate conditions. I think there might also be a health benefit in winter, with increased blood volume assisting with healing and recovery at a time when blood volume can naturally contract by more than 10%. 

My very loose suggestion: talk to a doctor. After the doctor approves, consider a background heat stimulus year-round if you enjoy it (possibly conducted in a manner that can spur heat shock proteins, though always being safe). Examples include a sauna, hot bath, hot tub, or heat suit. Don't overdo it-heat is a major stress, and it can be dangerous. Please be careful.

I personally like to aim for 2 heat exposures a week, with one on my rest day and the other one whenever I have time, usually consisting of 15-25 minutes in the sauna or hot bath (getting out whenever my heart rate gets above 120, and being extra careful in hot baths since I seem more sensitive to them). A typical week when not doing specific heat training for a hot event might look like this:

The jury is still out on whether the hemoglobin mass increases from heat training seen in studies will apply to everyone (or anyone in the real world who isn't doing 50-minute bike sessions in their entire wardrobe). So most of all, consider this intervention if it's FUN, a way to add a bit more sweat to your day, and only if it's approved by your doctor, lawyer, family, and life insurance salesperson. 

There are some cool adaptations at the limits of our physiology. And the coolest part about heat: you may be able to explore some of those adaptations while soft pedaling in a couple layers of clothes, sitting on a wood bench, or taking a relaxing bath. 

 

 

The prospect of seeing one of athletics' biggest stars back on the track is growing stronger, with Jakob Ingebrigtsen reportedly targeting a return to competition later this summer following his recovery from Achilles tendon surgery.

According to comments made by his agent, Daniel Wessfeldt, in an interview with Norwegian media, the double Olympic champion could make his long-awaited comeback at one of three major European meetings in July. The leading options under consideration are the Monaco Diamond League on July 10, the Hungarian Athletics Grand Prix on July 14, and the London Diamond League on July 18.

For athletics fans, the possibility of Ingebrigtsen lining up in London would add another layer of excitement to an already highly anticipated Diamond League meeting. The Norwegian middle-distance sensation has become one of the sport's most dominant figures in recent years, collecting Olympic, world and European titles while consistently rewriting record books.

His 2026 campaign was put on hold after he underwent surgery on his Achilles tendon earlier this year, forcing him to focus on rehabilitation rather than competition. Since then, questions have surrounded when the 24-year-old would be ready to return to racing.

The latest update suggests that decision will largely depend on how his training progresses over the coming weeks. If recovery continues according to plan, July could mark the beginning of his return to elite competition ahead of the latter stages of the season.

A comeback at either Monaco, Budapest or London would immediately place Ingebrigtsen back among the sport's biggest storylines. Each meeting is renowned for producing world-class performances, and any appearance by the Norwegian would attract significant attention from fans eager to see how quickly he can regain top form after his injury setback.

While no final decision has been confirmed, the signs are increasingly positive. After months away from competition, Jakob Ingebrigtsen appears to be edging closer to a return, with London's Diamond League meeting emerging as one of the most intriguing possibilities on his road back to the track.

Should his recovery continue smoothly, athletics could soon welcome back one of its brightest and most influential stars.

What should have been the defining moment of Emad Bashir-Mohammed's young running career instead turned into one of the most talked-about controversies in American road racing this year.

The 23-year-old crossed the finish line first in the men's citizen's race at the prestigious Bolder Boulder 10K on Memorial Day in Colorado, stopping the clock at an impressive 29:50. His performance was not only a commanding victory but also one of the fastest winning times ever recorded in the event's long and celebrated history. Bashir-Mohammed finished eight seconds clear of his nearest challenger and appeared to have secured a breakthrough triumph.

For nearly two hours, he was the undisputed winner.

Then everything changed.

Race officials announced that Bashir-Mohammed had been disqualified after determining that he had started in the wrong wave. According to Bolder Boulder regulations, he had been assigned to the AA wave but lined up with the faster A wave, which began earlier. Event rules allow runners to move backward into a slower wave, but prohibit athletes from advancing into a faster one.

As a result, Bashir-Mohammed's victory was erased from the record books.

The citizen's title was subsequently awarded to Nickolas Scudder, who crossed the line second in 29:58. The promotion handed Scudder back-to-back citizen's race victories, while Bashir-Mohammed was left to grapple with the disappointment of losing a win he believed he had earned on the road.

The disqualification has since ignited widespread debate across the running community.

Bashir-Mohammed maintains that he did not intentionally violate the rules. He claims that after collecting his AA bib, he spoke with race personnel and was permitted to start with the A wave after presenting evidence of his recent performances. In a statement shared after the race, he expressed frustration over the decision, arguing that his goal was simply to compete against the strongest field available and produce the fastest time possible.

Race organizers, however, stood firmly behind their ruling. Officials stated that wave-assignment regulations are clearly communicated in pre-race information and reiterated during packet collection. They also noted that hundreds of participants are disqualified each year for moving into faster start groups, emphasizing that consistent enforcement is necessary to maintain fairness for all competitors.

The incident has divided opinion among runners and fans alike. Some believe the rules must be applied equally regardless of an athlete's finishing position, arguing that wave assignments are a fundamental part of race organization. Others feel the punishment is harsh, particularly if Bashir-Mohammed genuinely received approval to move up before the start.

What remains undisputed is the quality of his performance. On the roads of Boulder, Bashir-Mohammed demonstrated the fitness and speed required to outrun the field by a significant margin. Yet in road racing, crossing the finish line first is only part of the equation. Compliance with race regulations carries equal weight.

For Bashir-Mohammed, the day will be remembered as a painful lesson in the fine margins that can define elite competition. A remarkable run delivered a memorable victory, but a dispute over wave placement ultimately overshadowed the achievement, leaving behind a controversy that continues to fuel discussion throughout the running world.

A fast race, a costly administrative error, and a debate that may linger long after the finish-line tape has been packed away.

The men's 100 metres at the 2026 Rome Diamond League is shaping up to be one of the most anticipated sprint races of the season, with an exceptional field featuring some of the fastest men in the world.

Scheduled for Thursday, June 4, at the iconic Stadio Olimpico in Rome, the race will bring together reigning stars, established champions and emerging talents in a contest that promises fireworks from the moment the gun goes off.

Kenya's Ferdinand Omanyala headlines a world-class lineup that includes American sprint sensation Noah Lyles, Botswana's Olympic champion Letsile Tebogo, Jamaica's explosive Ackeem Blake, South Africa's ever-consistent Akani Simbine and Italy's hometown hero Lamont Marcell Jacobs. With personal bests ranging from 9.77 to 9.97 seconds, the field is packed with athletes capable of producing something special on the Diamond League stage.

Omanyala, the African record holder with a blistering personal best of 9.77 seconds, arrives in Rome eager to continue his strong early-season form and prove he can challenge the very best on the global circuit. The Kenyan star has built a reputation as one of the fastest starters in world sprinting and will be looking to make a statement against an elite field.

Standing in his way is world champion Noah Lyles, whose personal best of 9.79 seconds places him among the fastest athletes in history. The American remains one of the sport's biggest attractions and will be determined to add another Diamond League victory to his impressive résumé.

The race also marks a major test for Olympic champion Letsile Tebogo. The Botswanan star has rapidly become one of athletics' most exciting talents, while Ackeem Blake continues to establish himself as a serious contender on the international sprint scene.

Adding further intrigue is the presence of Italy's Lamont Marcell Jacobs. Competing on home soil, the Tokyo Olympic champion will enjoy passionate local support as he seeks to deliver a memorable performance in front of the Roman crowd.

South Africa's Akani Simbine, Cameroon's Emmanuel Eseme, Great Britain's Jeremiah Azu and rising American talent Jordan Anthony complete a field that boasts remarkable depth and quality.

Men's 100m Entry List – Rome Diamond League 2026

Ferdinand Omanyala (Kenya) – PB: 9.77

Noah Lyles (USA) – PB: 9.79

Lamont Marcell Jacobs (Italy) – PB: 9.80

Akani Simbine (South Africa) – PB: 9.82

Letsile Tebogo (Botswana) – PB: 9.86

Ackeem Blake (Jamaica) – PB: 9.88

Jordan Anthony (USA) – PB: 9.91

Emmanuel Eseme (Cameroon) – PB: 9.96

Jeremiah Azu (Great Britain) – PB: 9.97

With multiple national record holders, global champions and Olympic medal contenders sharing the same start line, the Rome Diamond League men's 100m could deliver one of the fastest races of the year. For sprint fans around the world, all eyes will be on Rome as a stellar cast battles for supremacy over athletics' blue-riband distance.

Audrey Werro announced her arrival as one of the early stars of the 2026 outdoor season with a commanding victory in the women’s 800 metres at the Rabat Diamond League, producing a performance that exceeded even her own expectations.

The Swiss middle-distance talent surged to victory in a brilliant 1:56.56, breaking the meeting record and delivering one of the fastest times recorded worldwide this season. In a race packed with quality, Werro displayed exceptional composure, confidence, and finishing strength to separate herself from the field and stamp her authority on the event.

What made the performance even more remarkable was the athlete's surprise at the level she had already reached so early in the campaign.

"I was not expecting such a strong start to the season," Werro admitted after the race.

The race unfolded at a relentless pace, but Werro remained perfectly positioned throughout. As the athletes approached the bell lap, she glanced at the clock and immediately sensed something special was within reach.

"When I saw the time at the bell, I felt really confident," she said. "I'm really happy with the Meeting Record and looking forward to the rest of the season."

Her confidence proved justified. Maintaining her rhythm over the final 400 metres, Werro powered down the home straight to secure the victory and rewrite the Rabat meeting record books in the process.

The performance sends an early warning to her rivals ahead of a season that promises major championships and high-profile Diamond League battles. Beyond the record-breaking time, Werro's display highlighted her growing maturity as a racer, combining tactical awareness with impressive speed and endurance.

With the outdoor season only beginning, the 1:56.56 clocking suggests that even faster times could be on the horizon. If Rabat is any indication, Audrey Werro may be poised for the biggest season of her career.

Her emphatic victory in Morocco was more than just another Diamond League win—it was a statement of intent from an athlete determined to challenge the world's best throughout 2026.

The city of Boston is set to welcome back one of its most celebrated champions as Kenya’s Sharon Lokedi headlines a world-class field for the 2026 B.A.A. 10K presented by Mass General Brigham Cancer Institute on June 21.

Fresh from another remarkable victory at the Boston Marathon in April, Lokedi returns to the streets of Boston and Cambridge carrying both momentum and confidence as she aims to defend the title she captured in dominant fashion last year.

The two-time Boston Marathon champion has developed a special connection with the historic race city. In 2025, she produced a course-record performance of 2:17:22 to win the Boston Marathon before returning this year to claim another victory in 2:18:51, the second-fastest winning time in the event’s storied history. Her success has cemented her status as one of the premier road runners in the world.

Lokedi will be making her first competitive appearance since her marathon triumph and arrives as the reigning B.A.A. 10K champion after clocking 31:39 over the challenging 6.2-mile course in 2025.

“Boston has become a very special place for me,” Lokedi said ahead of the race. “The atmosphere created by the fans and the community is unlike anywhere else. I’m excited to return and give everything I have to defend my title.”

The women’s race promises to be highly competitive. American Olympian Rachel Smith, who finished second at the Boston 5K in April, leads the domestic challenge. Kenya’s strong contingent includes African 10,000m champion Gladys Kwamboka, former B.A.A. 10K runner-up Stacy Ndiwa, and experienced road racer Viola Cheptoo. British Olympian Jessica Warner-Judd adds further international depth to a field packed with proven performers.

The men’s race is equally impressive, featuring elite athletes from 13 nations.

Ethiopia’s Dawit Seare enters as one of the leading contenders after capturing the 2025 Boston 5K title and bringing the fastest 10K personal best in the field at 27:21. Kenya will be represented by an accomplished group led by Alexander Mutiso, winner of the 2024 London Marathon and runner-up at last year’s New York City Marathon.

Patrick Kiprop also arrives in outstanding form after securing victory at the prestigious BolderBoulder 10K on Memorial Day, while Alex Masai returns looking to continue his strong record in Boston. Masai recently finished ninth at the Boston Marathon and has earned three top-ten finishes at the B.A.A. 10K.

Among the international stars making their mark is South Africa’s Adriaan Wildschutt, who makes his race debut after an impressive season highlighted by victory at the NYC Half Marathon in 59:30. Ethiopia’s Olympic bronze medallist Hagos Gebrhiwet adds further quality to the field, bringing a wealth of championship experience and previous success in Boston.

Canadian national 10K champion Andrew Alexander, two-time U.S. Olympian Hillary Bor, marathon standout Ryan Ford, and reigning USA 25K champion Andrew Colley complete a field stacked with talent and depth.

With defending champions, Olympic finalists, national champions and rising stars all converging on Boston, the 2026 B.A.A. 10K is shaping up to be one of the most competitive editions in recent memory. For Sharon Lokedi, however, the mission is simple: return to the city where she has repeatedly excelled and add another memorable chapter to her growing Boston legacy.