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I’m always looking for possible interventions that can improve the health and performance of athletes I coach. It usually starts with a problem to solve. Here, I’m writing this article in December because the problem is that cross-population injury rates seem to go slightly up and overall performance seems to go slightly down in winter. There aren’t great studies to validate that hypothesis, but a 2014 master’s thesis found higher rates of musculoskeletal injury in winter months, attributing that increase to cold, icy and hard surfaces (cue Frosty the Snowperson saying, “That’s what she said”). And, in coaching, I rarely see the same levels of rapid progression in winter as in the other seasons, even controlling for training approach and background.

So we have the problem, and it boils down to this: screw winter.

There are plenty of possible reasons for performance and health reduction during winter. Some options include the cold’s impact on blood flow, slippery surfaces affecting form, reduced Vitamin-D levels, lower motivation, fatigue from past training and inadequate ice-cream intake. I’m sure you can think of a bunch of others. But in thinking about this topic way too much over the years, I kept coming back to another explanation. Maybe it’s related (at least partially) to blood volume.

A reduction in blood volume (primarily via plasma volume, consisting mainly of the water content in blood) during winter has been observed for nearly 100 years (see this 1940 article in the American Journal of Physiology). A 1950 article in the Journal of Physiology pegged the seasonal blood-volume difference at 8.6%, and subsequent estimates have varied around that number depending on where you look. While there is no set number for every person, that 1950 article is titled “Seasonal Changes in Human Body Fluids,” so I know I trust it.

There are a few principles related to blood volume that could be important here.

One, as outlined by a 2010 article in the Journal of Applied Physiology, heat acclimation and increased blood volume can be associated with improved performance in both hot and temperate conditions. Two, there is growing evidence that hemoglobin mass may be affected by blood-plasma volume changes. A 2019 study in Frontiers of Physiology and a 2020 study in Experimental Physiology found that hemoglobin mass increases after plasma volume increases in athletes training in the heat. Three, both plasma volume and hemoglobin mass may impact how the body performs, heals, and adapts. The physiology of how it works gets complicated and is not 100% direct (incorporating seasonal changes in hematocrit, or the ratio of red blood cells in total blood volume), so the exact relationships are not always certain.

The million dollar question follows: how the heck would those principles apply in winter? Each of those blood-volume concepts is based on beneficial adaptations to heat, so when thinking about winter we are extrapolating the inverse—negative adaptations to lack of heat. Perhaps the body adapts to cold weather with time and none of the issues are relevant when that equilibrium is reached. There are studies on seasonal hematological variation (see this 2013 review in Sports Medicine) that do not provide a definitive answer for athletes. In addition, there is no settled evidence that cold-weather performance is significantly affected by heat adaptation (2014 review in Sports Medicine), so that part may not be relevant at all.

Either way, we do know that blood volume usually decreases in winter and increases in summer. I have written articles on heat acclimation to improve performance and blood volume’s role for fitness, but there are no perfect studies looking at the training question I can’t stop thinking about. If blood volume is important in summer, might it also be something to think about (at least a little bit) in winter?

I think it might be.

That sentence is powerful prose, I know. The conclusions to come rely on the physiological theory that blood volume matters for athletes even in cold conditions (which is debated), and that natural, seasonal reductions in blood volume could affect injury rates and performance. Perhaps that is part of why Scandanvian athletes are so famous for their saunas (fun side note: there are 2.2 million saunas in Finland for a population of just over 5 million people). And all that prelude brings us to the topic of the article: hot-water immersion via baths or tubs could play a role in winter health and performance.

Let’s take a step back first. We have known for a long time that exposure to heat causes rapid expansion of blood volume. As outlined in a 2000 review article in the Medicine & Science in Sport & Exercise journal, total blood volume is primarily composed of the sum of erythrocyte volume (red blood cells) and plasma volume (mostly water plus some dissolved proteins, glucose, clotting factors, electrolytes, hormones and other components). Plasma volume can adapt to environmental changes rapidly. For example, a 2015 study in the European Journal of Applied Physiology found a 17.8% increase in plasma volume in highly trained cyclists after just four exposures to post-exercise sauna. Plenty of other studies back that up. And recent studies tie those plasma volume increases to red-blood-cell-volume increases too.

Hot-Water Immersion Studies

A 2015 study in the Scandinavian Journal of Medicine & Science in Sports had 17 non-heat-acclimated males do a 40-minute easy run every day for six days, followed by hot-water immersion in 104 degrees F water (40 degrees C) for 32 to 40 minutes. The hot water caused heat acclimation similar to what would be expected from traditional sauna protocols—lower skin temperature and perceived exertion in temperate and hot running, improved performance in hot running and a non-significant improvement in temperate running. The study did not measure blood volume, but those adaptations are likely at least partially associated with increased plasma volume.

A 2018 study in Frontiers of Physiology followed up on those findings, based on the assumption that the principles may apply differently to trained endurance athletes since there is some amount of heat training in normal running at baseline. The study used the same protocol, but with eight trained athletes and eight untrained athletes. The findings of the 2015 study were reproduced in both groups. A 2019 study in Frontiers of Physiology found that athletes following the protocol retained the heat acclimation benefits for at least two weeks. Yet another 2019 study in Frontiers of Physiology found that delaying the hot-water exposure from right after exercise to eight hours later still had similar benefits, though of slightly less magnitude.

That’s all conjecture, so the exact mechanism isn’t the most important thing in the world. What matters more is the general principle that some passive heat exposure could be helpful even in winter months.

If you have a hot tub, consider spending some time in it. I wouldn’t suggest mimicking the study protocols unless you have a doctor and a crash cart on site, since 30 to 40 minutes at 104 degrees F could cause a deadly case of prune fingers and an even deadlier case of heart attack. But all of these benefits likely happen on a spectrum, so some time in the tub will likely have some benefits, even if they’re not as rapidly undeniable as the six-day protocols in the study.

Most of us will not have a hot tub, though, unless that student debt forgiveness plan goes through. So what are we to do? In the last few years, a few athletes I coach have sworn by hot baths for the same purpose. Their anecdotes are powerful enough that my wife Megan and I both take hot baths each day.

Now we get to the good stuff.

We have the problem: winter can suck for running health and performance. We have a hypothesis: that suckitude may at least partially be related to natural changes in blood volume. We have data that may be relevant: studies show heat acclimation is partially associated with increased blood plasma volume, and that hot-water immersion improves heat acclimation, likely increasing blood plasma volume. Now let’s conclude with another unproven (possibly wrong) hypothesis: hot-water immersion could make winter running more fun by giving blood volume a helpful nudge when it wants to go to sleep for the season.

Does it make a difference? I have no freaking clue. My routine is to fill up the bathtub with some soothing hot water and meditate for 10 to 20 minutes (by meditate, I mean listen to a bumping playlist), until I break a nice sweat. The first week I did it this year, my heart rate after 10 minutes was 10 to 20 beats per minute higher than it is now, possibly indicative of some acclimation effects over time, but that’s subject to tons of confounding variables.

Long story short: There is some physiological basis for benefits from hot baths or hot tubs (or even extra hot showers), both in winter and summer. However, the evidence is by no means definitive or even overly persuasive outside of the extensive study protocols. But I do know this for a fact: Some time in a hot bath is awfully relaxing.

And whether it’s winter or not, we could all use a little bit of extra time to relax.

Most Olympic marathoners spend their youth focused on running. They join track clubs, compete in national championships, and pursue the sport from an early age.

Julia Mayer’s journey was very different.

Today, Mayer is Austria’s marathon record holder, a multiple national record holder on the roads, and an Olympian. Yet for much of her athletic life, running was not her primary sport.

For 16 years, she played soccer.

Then she discovered something that would change her life.

“I noticed that I was really fast in the fun runs and that it was really, really fun,” Mayer said when reflecting on her transition from soccer to distance running.

What began as curiosity quickly became a passion. She eventually made the bold decision to leave soccer behind and focus entirely on running. It was a move that surprised many people around her, but Mayer believed she had found her true athletic calling.

The decision proved to be the right one.

Within a few years, Mayer developed into one of Europe’s top marathon runners. Her steady improvement carried her from local races to the international stage, where she began rewriting Austria’s record books.

She now holds Austrian records in the marathon, half marathon, and road 10K. Her marathon best of 2:26:08 established her as the fastest female marathoner in Austrian history. Her performances in the half marathon and 10K have further cemented her place among the country’s all-time great distance runners.

Her rise culminated with qualification for the 2024 Olympic Games in Paris.

Competing in the Olympic marathon represented the realization of a dream. On one of the most challenging marathon courses ever used for the Olympics, Mayer ran courageously against the strongest field in the world and finished 55th in her Olympic debut.

Behind the scenes, success has come through extraordinary dedication. During marathon preparation, Mayer trains twice a day and covers approximately 200 kilometers, or 124 miles, each week. The workload demands discipline, patience, and a deep commitment to continuous improvement. 

What makes her story especially inspiring is not simply the records or the Olympic appearance.

It is the fact that she found her greatest talent later than many elite runners.

In a sport where athletes are often identified at a young age, Mayer’s journey serves as a reminder that potential does not always reveal itself early. Sometimes it takes years of experience, a willingness to try something new, and the courage to follow a different path. 

The former soccer player who once chased a ball across a field is now chasing history on the roads of Europe.

And according to those closest to her, her best performances may still be ahead.

For runners of every age and ability, Julia Mayer’s story delivers a powerful lesson: it is never too late to discover what you are capable of.

From soccer player to Olympian, her journey proves that remarkable achievements can begin when least expected.

Megan Keith produced the performance of her career in Oslo on Thursday night, shattering one of Scotland’s longest-standing distance running records and cementing her place among Britain’s greatest female 3000m runners.

The 24-year-old clocked a sensational 8:28.35 over 3000m, breaking the Scottish outdoor record that had stood for nearly four decades. In doing so, Keith eclipsed the previous mark of 8:29.02, set by Scottish legend Yvonne Murray back in 1988, ending a record reign that had lasted 38 years.

Keith’s breakthrough run was more than just a national record. The performance also propelled her to third on the UK outdoor all-time list, placing her behind only two of Britain’s most celebrated distance runners — Paula Radcliffe, who leads the rankings with 8:22.20, and Laura Weightman, whose 8:26.07 remains the second-fastest outdoor mark by a British woman.

The significance of Keith’s achievement is amplified by the calibre of athletes she now joins in the record books. For decades, Murray’s mark stood as one of Scottish athletics’ most untouchable records, surviving generations of elite competitors. Keith has now succeeded where many outstanding runners have fallen short, announcing herself as one of the leading distance talents in British athletics.

Her time also compares favourably with the best performances produced indoors. Olympic medallist Laura Muir ran 8:26.41 indoors in Karlsruhe in 2017, underlining just how exceptional Keith’s outdoor effort in Oslo truly was.

The run continues a remarkable rise for the Scottish star, whose progression over recent seasons has transformed her from a promising prospect into a genuine force on the international stage. Running with confidence and composure against elite competition, Keith demonstrated both the speed and endurance required to challenge the very best in Europe and beyond.

With the World Championship season gathering momentum, Keith’s record-breaking display sends a powerful message. Not only has she etched her name into Scottish athletics history, but she has also established herself as a serious contender in one of the sport’s most competitive events.

In Oslo, Megan Keith did far more than break a record. She ended a 38-year wait, climbed into the upper echelon of British distance running, and delivered a performance that may prove to be a defining moment in her career.

British middle-distance talent Phoebe Gill took another significant step forward in her return to top form, producing a determined victory over 800 metres at the Meeting de Marseille in France on Wednesday.

Competing in challenging, wind-affected conditions, the 19-year-old demonstrated both resilience and composure as she held off a late charge from Switzerland's Veronica Vancardo to secure the win in 2:00.81. Vancardo finished just three hundredths of a second behind in 2:00.84, underlining the fiercely contested nature of the race.

While the margin of victory was narrow, the result represented another encouraging milestone for Gill as she continues to rebuild momentum following her injury setback. The young Briton showed impressive race awareness and strength in the closing stages, maintaining her advantage despite the difficult conditions that made fast running a challenge throughout the evening.

The Marseille triumph adds to a growing body of evidence that Gill is steadily progressing toward her best form. Earlier in her comeback campaign, she clocked 2:01.50 for 800m in Bydgoszcz before demonstrating her versatility with a strong 4:05.53 performance over 1500 metres at the BMC Grand Prix meeting in Trafford.

Those performances have highlighted not only her improving fitness but also her ability to compete across multiple distances as she carefully builds her season. The Marseille victory now provides further confirmation that the European junior star is moving in the right direction.

Gill emerged as one of Britain's most exciting middle-distance prospects through a series of breakthrough performances as a teenager, earning widespread recognition for her fearless racing style and remarkable maturity. Injury temporarily interrupted that upward trajectory, but her recent results suggest she is steadily rediscovering the form that made her one of the sport's brightest young talents.

With each race, the signs of progress become increasingly evident. Winning in difficult conditions and under pressure from a quality field is often a stronger indicator than a fast time alone, and Gill's latest success demonstrated exactly those qualities.

As the summer season gathers pace, the Marseille victory offers another confidence boost for the British teenager, whose return continues to gain momentum. If her recent progression is any indication, Gill could soon find herself back among the leading names on the European middle-distance circuit. 

The NCAA Track and Field Championships delivered a moment few could have predicted as Ja’Kobe Tharp produced one of the most astonishing performances in the history of sprint hurdling, rewriting the record books in spectacular fashion.

Competing in the opening round of the men’s 110-meter hurdles, the Auburn star stunned the athletics world by clocking an incredible 12.75 seconds, becoming the first athlete ever to break the 12.80-second barrier. In doing so, he eclipsed the long-standing world record of 12.80 set by Aries Merritt in 2012, a mark that had stood as one of the sport’s most revered achievements for more than a decade.

What makes Tharp’s breakthrough even more remarkable is the scale of his improvement. Entering the championships, the defending NCAA and U.S. champion had recorded a season-best of 13.05 seconds. Yet under the brightest spotlight, he unleashed a performance that exceeded every expectation, slicing an extraordinary 0.26 seconds from his personal best in a race that instantly became one of the greatest ever run.

The achievement sent shockwaves throughout the track and field community. While Tharp arrived in Eugene as one of the leading contenders for the NCAA title, few envisioned a performance capable of redefining the limits of the event. Instead, the American hurdler delivered a race for the ages, combining flawless technique, explosive speed, and impeccable rhythm from the first hurdle to the finish line.

The historic run not only secured his place in athletics history but also transformed the outlook of the championship. With the world record now in his possession, Tharp advances to the final as the overwhelming favorite, carrying momentum that could make an already unforgettable weekend even more extraordinary.

For years, the 12.80 barrier appeared untouchable. On a stunning day at the NCAA Championships, Ja’Kobe Tharp proved otherwise, producing the kind of performance that reminds fans why sport remains so unpredictable. In a matter of seconds, he turned a routine qualifying round into a landmark moment that will be remembered for generations.

The world record no one saw coming is now a reality—and Ja’Kobe Tharp is the man who changed history.

A new chapter in middle-distance running may have begun in Oslo after American teenager Cooper Lutkenhaus produced one of the most remarkable performances of the season, narrowly defeating reigning Olympic champion Emmanuel Wanyonyi in a thrilling men's 800m contest at the Diamond League meeting.

The 17-year-old sensation shocked a world-class field by crossing the finish line first in a race that came down to the smallest of margins. After an intense battle over the final metres, Lutkenhaus held off Wanyonyi by just one hundredth of a second, producing a dramatic finish that left the packed stadium in disbelief.

From the opening lap, the pace was relentless as the leading contenders positioned themselves for a fierce showdown. As the athletes entered the home straight, Wanyonyi appeared poised to unleash his trademark finishing kick. However, Lutkenhaus refused to be intimidated, matching the Olympic champion stride for stride before producing a perfectly timed lean at the line to secure a historic victory.

The result marks a breakthrough moment for the young American, who continues to establish himself as one of the brightest talents in global athletics. Defeating an Olympic champion at a Diamond League event is a feat many athletes spend entire careers pursuing, yet Lutkenhaus achieved it before reaching adulthood.

For Wanyonyi, the narrow defeat does little to diminish his status as one of the world's premier 800m runners. The Kenyan once again demonstrated his exceptional class and competitiveness, pushing the race to a world-class standard and forcing his young rival to deliver the performance of a lifetime.

Beyond the result itself, the race offered a glimpse into what could become one of the sport's most exciting rivalries in the years ahead. With established stars and emerging talents now pushing each other to new heights, the men's 800m continues to evolve into one of athletics' most captivating events.

On a memorable night in Oslo, the spotlight belonged to Cooper Lutkenhaus. At just 17 years old, he stood toe-to-toe with an Olympic champion and emerged victorious, announcing himself to the athletics world in spectacular fashion.