If I told you that NASA has developed a radical new way of monitoring and quantifying your workouts, and that that method outperforms all others, you鈥檇 probably assume that it involves bleeding-edge science. There would be AI, and some sort of wearable or perhaps even injectable technology. It would be very expensive.

But you鈥檇 be wrong, for reasons that tell us something important about the quest to transform training optimization from an art into a science. A new study by Mattia D鈥橝lleva and his colleagues at the University of Udine compares different ways of assessing the 鈥渢raining load鈥� of different workouts鈥攁nd finds that a low-tech NASA questionnaire produces the most accurate results. The findings offer a reminder that outsourcing our training decisions to wearable tech algorithms 诲辞别蝉苍鈥檛 always outperform simply listening to our bodies. The research also raises a tricky question: is the workout that makes you most tired also the one that increases your fitness the most?

Why Does Training Load Matter?

The goal of training is to impose a stress鈥攁 training load鈥攐n your body that makes it tired in the short term but triggers adaptations that make it fitter in the long term. Going all-out in one workout isn鈥檛 constructive, even though it imposes a huge training load, because it leaves you too tired to train effectively the next day. The art of training is figuring out what mix of easy, medium, and hard workouts will enable you to accumulate the greatest possible training load over weeks and months without getting crippled by fatigue.

In its simplest form (as I discussed here), the training load of a workout is a combination of how hard you push and how long you push for. But the details get tricky. What鈥檚 the best measure for how hard you鈥檙e pushing? You could use pace, power, heart rate, heart rate variability, lactate levels, perceived effort, or other progressively more esoteric metrics. And how do you combine effort with duration? You can鈥檛 just multiply them together, because effort is nonlinear: running twice as fast for half the distance won鈥檛 produce the same training effect.

The , which is published in the International Journal of Sports Physiology and Performance, compares seven different ways of calculating training load. Four of them are variations on a concept known as TRIMP, which is short for 鈥渢raining impulse鈥� and is based on heart rate measurements, using equations that account for lactate levels, breathing thresholds, and other details. A fifth uses heart-rate variability, and a sixth uses a subjective rating of effort. (Most fitness wearables, by the way, likely use a combination of the above methods, though their exact algorithms are typically proprietary.) The seventh method is the NASA questionnaire, which we鈥檒l come back to.

The gold standard against which all these methods were compared is the 鈥渁cute performance decrement,鈥� or APD. Basically, you do an all-out time trial, then you do your workout, then you do another all-out time trial. Your APD is how much slower the second time-trial is compared to the first one, as a measure of how much the workout took out of you. Obviously this isn鈥檛 a practical way of monitoring training, because you can鈥檛 race before and after every workout. But for researchers, it鈥檚 a way of checking whether various methods鈥攊ncluding the seven they tested in this study鈥� correspond to the reality of how hard a workout is on your body. At the end, they were able to figure out which method was the most reliable predictor of training load.

What the New Study Found

D鈥橝lleva and his colleagues recruited 12 well-trained runners (10 men and 2 women) to test four different running workouts on different days:

• Low-intensity training (LIT): 60 minutes at a pre-determined comfortable pace
• Medium intensity (MIT): 2 x 12:00 at a moderate pace with 4:00 easy recovery
• Long high-intensity (HITlong): 5 x 3:00 hard with 2:00 recovery
• Short high-intensity (HITshort): two sets of 11 x 30 seconds hard, 30 seconds easy

The performance test was running at VO2 max pace until exhaustion. When they were fresh, the runners lasted just under six minutes on average. After the one-hour easy run, their APD was 20.7 percent, meaning they gave up 20.7 percent earlier in the post-workout VO2 max run. After the medium-intensity run, the APD was 30.6 percent; after the long intervals, it was 35.9 percent; after the short intervals, it was 29.8 percent.

So how well were each of the seven training load calculations able to predict this APD? The short answer is: not very well. Here鈥檚 a comparison of APD (on the left) and one of the parameters studied, which is called bTRIMP and is based on heart-rate measurements and lactate curves:

In fact, the relationships are completely reversed: the easiest workout according to bTRIMP produces the biggest APD in reality, and the workout ranked hardest by bTRIMP produces the smallest APD. All except two of the training load calculations the researchers measured have similar upside-down relationships. The two exceptions are heart-rate variability and the NASA questionnaire, which look like this:

The heart-rate variability measures, on the left, don鈥檛 tell us much, because they鈥檙e basically the same after each of the four workouts. (You can see some subtle differences, but they鈥檙e not statistically significant.) The NASA questionnaire, on the other hand, bears a striking resemblance to the APD data, and the statistical analysis confirms that it鈥檚 a good predictor. In other words, it鈥檚 the only one of the seven calculations tested that, according to this study, accurately reflects how exhausted you are after a workout.

So what is this questionnaire? It鈥檚 called the , or NASA-TLX, and was developed in the 1980s. It鈥檚 simply a set of six questions that ask you to rate the mental demand, physical demand, temporal demand (how rushed were you?), performance (how well did you do?), effort, and frustration of a task. You answer each of these questions on a scale of 1 to 100, then the six scores are averaged鈥攁nd presto, you have a better measure of how hard your workout was than your watch or heart-rate monitor can provide.

What the NASA Questionnaire Misses

These results don鈥檛 mean that we should all start recording NASA-TLX scores in our training logs. Questions like how hurried you felt don鈥檛 seem very relevant to running, or to training in general. What鈥檚 more significant about the questionnaire is what it 诲辞别蝉苍鈥檛 include: any measure of how long the workout was.

All the other training load measures rely on a combination of intensity and duration. But the effect of duration swamps the measurement: that鈥檚 why the bTRIMP graph above shows the 60-minute easy run (LIT) as the workout with the biggest training load. It鈥檚 really just telling us that it was the longest workout. The NASA-TLX, on the other hand, just asks (in various ways) how hard the workout felt once it was done. That turns out to be a better way of predicting how much slower you鈥檒l be after the workout.

There鈥檚 an implicit assumption in all of this discussion, though, which is that the workout that provides the biggest training load is the one that will improve your fitness the most. Is APD鈥攈ow much slower you get over the course of a single workout鈥攔eally the best predictor of fitness gains? It鈥檚 easy to come up with scenarios where that鈥檚 not true. If I sprain my ankle, my APD will be enormous, but that 诲辞别蝉苍鈥檛 mean I鈥檓 going to be an Olympic champion next month. Similarly, you can imagine workouts that would inflict a disproportionate amount of performance-sapping fatigue鈥攕teep downhill running, for example鈥攃ompared to their fitness benefits.

Perhaps what we鈥檙e seeing here is not so much 鈥済ood鈥� (NASA-TLX) and 鈥渂ad鈥� (TRIMP) measures of training load, but rather good measurements for two different types of training load. The APD and NASA-TLX mostly reflect how hard/intense/fast the workout was. TRIMPs and other metrics that incorporate duration end up mostly reflecting how long the workout was. There鈥檚 no reason to assume that these two parameters are interchangeable. It鈥檚 not just that you can鈥檛 get the same training benefit by going twice as fast for half as long. It鈥檚 that there鈥檚 no equation that makes fast running produce the same benefits as slow running. They鈥檙e two different physiological stimuli, and the smart money says you need both to maximize your performance.

So where does this leave us? I鈥檓 not anti-data, and I鈥檓 open to the idea that some of the newer metrics provided by wearable tech might reveal useful patterns if you collect them consistently. But if you strip training down to its bare essentials, these results suggest to me that there are two separate parameters that really matter: how long and how hard. And for now, I鈥檓 not convinced that we have any measuring tools that are significantly better than a stopwatch and an honest answer to the question 鈥淗ow did that feel?鈥�

For more Sweat Science, join me on and , sign up for the , and check out my new book .

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Back in 1969, naval researchers took blood samples from the crew of a Polaris nuclear submarine over the course of an eight-week patrol. Three-quarters of the sailors were smokers, so carbon monoxide levels were chronically elevated in the sealed confines of the sub. After a few weeks in this toxic miasma, the crew鈥檚 levels of hemoglobin, the crucial protein in red blood cells that ferries oxygen from the lungs to the muscles, had shot up by an average of 4.4 percent. Secondhand smoke had somehow turned the submariners into aerobic superstars.

This finding, along with others like it, was filed away for decades. After all, smoking destroys your lungs, so any performance benefits are outweighed by the harms. But then, last year, the idea exploded. Scientists published fresh data showing that huffing carbon monoxide could boost endurance. Other scientists responded with editorials warning against fooling around with a gas whose nickname is 鈥渢he silent killer.鈥� And headlines around the world trumpeted the news that 鈥攃onfirmation, seemingly, of the clich茅 that elite athletes will accept any risk in exchange for victory. The full story, though, is a bit more complicated.

The quest for endurance is, in part, about hemoglobin. More hemoglobin means more oxygen delivered to your muscles, which means you can run or ride or swim faster, for longer. Starve your muscles of oxygen in training and your body responds by secreting EPO, a hormone that stimulates the production of hemoglobin-carrying red blood cells. That鈥檚 how altitude training works: There鈥檚 less oxygen available, so your body produces more EPO to compensate. (It鈥檚 also why synthetic EPO is the banned drug of choice among endurance athletes.)

Virtually all performance-enhancing drugs are associated with health risks, and that hasn鈥檛 harmed their popularity.

When you inhale carbon monoxide, some of your red blood cells ferry molecules of it (instead of oxygen) around your body. Carbon monoxide attaches to hemoglobin and 诲辞别蝉苍鈥檛 let go, making those red blood cells unavailable to carry oxygen for many hours. It鈥檚 like altitude training in a bottle: Your body will sense the oxygen shortage and respond by producing EPO. But inhale too much and you won鈥檛 deliver sufficient oxygen to your heart and brain鈥攁nd once your hemoglobin is clogged with carbon monoxide, it鈥檚 not easy to reverse. Around 1,200 people die every year in the United States from deliberate or accidental carbon monoxide poisoning.

So carbon monoxide as a performance booster has been understood but mostly unspoken. It wasn鈥檛 until 2018 that the idea got more concrete. An initial study confirmed that deliberately breathing carbon monoxide boosted EPO. The next year, researchers in China, tasked with preparing their country鈥檚 athletes for the 2022 Beijing Winter Olympics, reported that college soccer players who inhaled the gas five times a week increased their hemoglobin levels. A , in which subjects inhaled the gas five times a day, reached similar conclusions. Most recently, a by researchers in Norway combined altitude training with twice-daily carbon monoxide inhalation for a synergistic effect.

But there hasn鈥檛 been a single verified report of an athlete actually using this technique. I reached out off-the-record to contacts in several elite endurance sports, as well as researchers in the field, and none of them had heard even rumors of real-life usage. The risk, so far, is theoretical. The headlines during the Tour de France referred to the use of small doses of carbon monoxide to measure hemoglobin levels. This technique has long been used in elite sport to check how athletes are responding to altitude training, but the doses are too low to boost performance. There is a gray area here: Once you鈥檝e got the carbon monoxide device in the team van, there鈥檚 a temptation to use it. But would elite athletes, these paragons of super-fitness, really take such a dumb risk?

Whether rational or not, we all accept nonzero risks in pursuit of goals.

It鈥檚 a fair question. In the 1980s and 鈥�90s, Chicago doctor Robert Goldman circulated a now-infamous series of questionnaires among elite athletes, asking if they would take an undetectable drug that would make them unbeatable for five years鈥攁nd then die of the side effects. Roughly half the athletes accepted the bargain, he reported. Goldman鈥檚 Dilemma, as it鈥檚 now known, is often cited as evidence of the modern athlete鈥檚 off-the-charts focus on winning, regardless of the costs. And indeed, virtually all performance-enhancing drugs are associated with health risks, and that hasn鈥檛 harmed their popularity. 鈥淵ou have guys who will go to the funeral of a friend who died from this stuff, come home, and inject it again,鈥� an anonymous Olympic runner told Sports Illustrated in a 1997 article about Goldman鈥檚 Dilemma.

But it鈥檚 not clear whether Goldman鈥檚 respondents were taking the question seriously, or whether attitudes have changed. Recent attempts to replicate Goldman鈥檚 results raise doubts. A 2018 study from Duke University estimated the 鈥渕aximum acceptable mortality risk鈥� that nearly 3,000 athletes would accept in exchange for the guarantee of Olympic gold. No one took the deal if it meant certain death. Depending on the sport and the level of competition, athletes were, on average, willing to accept somewhere between 7 and 14 percent risk of a fatal heart attack.

That鈥檚 still a big risk. But it鈥檚 comparable, the researchers point out, to the risks people say they鈥檙e willing to accept in exchange for other life-changing outcomes, like relief from their rheumatoid arthritis. And it鈥檚 not fundamentally different from the types of risk you might encounter on mountain expeditions, in extreme sports, or in the backcountry. Whether rational or not, we all accept some risks in pursuit of our goals. So it seems unlikely that the theoretical possibility of a fatal mishap will be enough, on its own, to dissuade athletes from trying to get a boost from carbon monoxide.

In February, the UCI, cycling鈥檚 international governing body, to boost performance, while the use of single doses to measure hemoglobin will still be allowed. This may seem like one of those wishy-washy compromises that鈥檚 almost impossible to enforce: the substance itself is permitted, but you have to promise you鈥檙e using it for the right reasons. But I think it鈥檚 the right call. Anti-doping agencies should, of course, be trying to catch unrepentant cheaters. But they also have a crucial role to play in setting broader norms about what risks we should or shouldn鈥檛 be willing to accept in pursuit of gold. Motivated athletes will do whatever the rules permit鈥攕o let鈥檚 not ask them to suck on a tailpipe five times a day, any more than we would lock them in a nuclear sub with a crew of chain-smokers.

This piece first appeared in the summer聽2025 print issue of 国产吃瓜黑料 Magazine. Subscribe now for early access to our most captivating storytelling, stunning photography, and deeply reported features on the biggest issues facing the outdoor world.

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Meet , , and 鈥� three content creators redefining what it means to be a triathlete in the digital era. With massive followings on TikTok and Instagram, they鈥檙e not just documenting workouts and race days 鈥� they鈥檙e inspiring a whole new generation to dive into the swim-bike-run life.

In this roundtable, we dig into the real impact of social media on the sport as Carolyn, Noel, and Nikki open up about the challenges and the perks of influencer life 鈥� and why they鈥檙e committed to showing the unserious side of the sport.

Triathlete: Let鈥檚 start from the top 鈥� why did you decide to share your triathlon journey on social media? Was it intentional or more organic?

Mulkey: It was super organic. I wasn鈥檛 planning to become an influencer. Around 2020, I was getting ready for a 100-mile bike ride and decided to do a simple 鈥済et ready with me鈥� video. I didn鈥檛 think anyone would care 鈥� but it blew up. It got like half a million likes overnight. That鈥檚 when I realized, 鈥淲ow, people are actually interested in this sport.鈥�

Hawkes: I鈥檝e been doing triathlons for maybe six years now, but I only started creating content properties in the last year and a half. At first, it was more just to hold myself accountable, but it evolved into this personal diary where I could look back on races and not take myself too seriously. My camera roll was full of me running, cycling, or swimming anyway, so I figured 鈥� why not make something out of it?

Carter: I started triathlon in 2016 and like Nikki, I was mainly documenting my journey for myself. It wasn鈥檛 until around 2022 that my account really started to grow. For me, it was pretty organic. When I started, there weren鈥檛 that many influencers in this space. I just posted race photos and then later made a reel that did really well, which got me more into content creation.

 

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Of the billions of accounts on social media, why do you think people are drawn to your content?

Mulkey: I don鈥檛 try to be anything I鈥檓 not. My videos aren鈥檛 overly edited 鈥� you can see the mess in the background of my vlogs sometimes. I鈥檓 an open book. I think people connect with that kind of raw honesty.

Hawkes: I can be quite spicy, and I think that stands out. Also, I鈥檓 really consistent with my branding. I always call my followers 鈥渓ittle beans,鈥� and I think people remember that, even if they don鈥檛 necessarily like me. It sticks with them, whether they鈥檙e rolling their eyes or laughing.

Carter: For me, it鈥檚 about being funny and making light of the sport. I also think the whole idea of being a 鈥渟low pro鈥� is unique. I鈥檓 not the fastest, but I still got my pro card, and I think that shows people that it鈥檚 possible, even if you鈥檙e not super fast. I like to make that goal feel attainable for others.

Is that the goal with your platform? To make the sport more approachable?

Hawkes: The internet can sometimes make triathlon feel way more complicated than it is, with all these crazy coaching plans and gear recommendations. My goal is to make it clear that you can be an average Joe and still take on those big races. Plus, I want to entertain people! I want to make you laugh and forget about your problems for a bit.

1 planned cafe stop and one impromptu one when we came across a charity bake sale Total cycle was about 119km by the time I got home

Carter: When I started triathlon, I was pretty young, and honestly, the sport was really intimidating. I didn鈥檛 see many women out there at my age doing this. So I try to create content that鈥檚 welcoming and helpful for people, especially women, who might be in the same spot I was in back then.

Mulkey: I鈥檝e been in this the longest, and at this point, I have realized that my end game is to just help people, whether it鈥檚 to build mental health awareness or to talk about sobriety 鈥� I鈥檓 open about having bipolar two disorder and my past addiction 鈥� and to inspire them to change their life. That wasn鈥檛 my intention setting out, but now it鈥檚 kind of morphed into that.

Let鈥檚 talk about content creation. How do you come up with fresh takes on swim, bike, and run?

Carter: A lot of times, I scroll through social media in the evenings to get inspired by trending audio or something funny I can make into content. But often, I鈥檒l just be on a ride or a run, and an idea will pop into my head. I鈥檒l jot it down in my notes app and then film it later. If I鈥檓 on a particularly beautiful ride, I鈥檒l make sure to grab clips. So, it鈥檚 a little chaotic, but it works!

Hawkes: Oh my gosh, my notes app is a complete mess! I write down anything that comes to mind, whether it鈥檚 something funny I hear or a meme I find. I don鈥檛 really have a strategy, but I鈥檒l try to create a storyline if I鈥檓 building up to a race.

Mulkey: Most of it鈥檚 off the cuff. You can probably tell. I used to be way more organized, especially when I was making a lot of money the first few years. But recently, after injuries and a less-exciting year, I鈥檝e just been posting whatever鈥檚 happening in my life. It鈥檚 second nature for me to just pull out my phone and film stuff.

Do you feel like you are actually influencing people to get into triathlon?

Carter: I do get messages from people who鈥檝e never done a triathlon and want to try it. They鈥檒l tell me I鈥檝e inspired them to do their first race, and that鈥檚 the ultimate reward. I鈥檒l also get recognized at races, which is pretty cool. It鈥檚 such a fun community.

Hawkes: I鈥檓 more on TikTok, and I find that there鈥檚 a different, younger audience over there. They鈥檙e new to triathlon, so I do get a lot of questions from followers. Like, 鈥淲hat shoes do I get?鈥� 鈥淲hat outfits do I wear?鈥� 鈥淗ow do I get into this?鈥�

Mulkey: People have told me my videos are the reason they started riding or signed up for a race. I never expected that kind of impact, and it鈥檚 been the coolest, most humbling part of it all.

 

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So let鈥檚 talk about the darker side of social media. Noel, as the OG of the group, can you speak to that?

Mulkey: When I first went viral, people didn鈥檛 know how to label me based on my voice or appearance. I posted this video on TikTok of me winning a race, and it got a ton of hate. People thought I was a trans woman competing in the women鈥檚 category. Every comment 鈥� thousands of them 鈥� were just hateful. I couldn鈥檛 read them. It was driving me nuts. But once I found a real community, the positive outweighed the negative. These days, when a reel goes viral, it鈥檚 shown to a new audience, which can bring fresh hate, but honestly, after six years, it 诲辞别蝉苍鈥檛 phase me anymore. I鈥檒l even clap back sometimes 鈥� I don鈥檛 mind saying something. But it 诲辞别蝉苍鈥檛 cut the way it used to.

How do you build up that resilience?

Mulkey: I鈥檝e trained myself not to give it that much mental energy. Comments help engagement anyway. And once I found my community, it was really cool 鈥� like, they鈥檒l defend me when trolls come in. I have a whole little army now.聽 There were times when things got stressful, especially when I was really busy with brands. But the negative comments are never going to make me want to walk away.

You each put it all out there, including the build-up to big races. So if you have a bad day out there, do you feel like you owe the world an explanation?

Carter: My first pro race was Santa Cruz 70.3 in 2022, and I just had a terrible race. I cramped, didn鈥檛 feel well, and it was just a mess. So many people were tracking me, and I knew I had to say what went wrong. But honestly, I posted about it, shared my mistakes, and everyone was super supportive. Most people get it 鈥� bad races happen, and there鈥檚 no shame in that.

Hawkes: I feel like I鈥檝e been pretty open about my journey, and I tell people that I鈥檓 not a pro, I鈥檓 just someone training while working a full-time job. That makes it feel more real, and people appreciate the honesty.

Mulkey: Back in the day, I used to be self-conscious 鈥� like, 鈥淥h no, this race went bad, what do I say?鈥� But now? I鈥檒l say exactly what happened. I don鈥檛 care. One of my best videos was after I did an 11.5-hour Ironman in Kona, which was really, really bad for me, and I was just honest. Turns out, people really connect with the tough days more than the good ones. I always tell people, don鈥檛 go silent after a bad race. Just be real. No one鈥檚 judging you the way you think they are.

What about when you put content out there and it 诲辞别蝉苍鈥檛 perform as well as you hoped? Do you take it personally?

Carter: Oh, definitely! I think it affects everyone. Instagram鈥檚 algorithm changes all the time, so one month reels are the thing, and the next it鈥檚 all about carousels. It鈥檚 hard not to take it personally when something 诲辞别蝉苍鈥檛 do well, especially if you put a lot of effort into it. But I try to remind myself that it鈥檚 not always about the content 鈥� it could just be the algorithm.

Hawkes: I do, yes. I try not to take it personally, but sometimes it鈥檚 hard not to. The algorithm is constantly changing, and it can be frustrating. I just try to make content that I enjoy creating and hope others enjoy it too. If it 诲辞别蝉苍鈥檛 do well, I remind myself that it鈥檚 just the algorithm, not necessarily the content. It does feel personal, though, sometimes.

Mulkey: It鈥檚 funny. The more time I spend on something, the worse it performs. I think we each have our own flavor, and if I try to be something I鈥檓 not, people are going to see through that. They won鈥檛 like it if it鈥檚 not what they鈥檙e used to.

OK, so spill a bit about the perks of being a triathlon influencer.

Mulkey: There have been so many! I鈥檝e gotten some awesome trips out of this. Ironman flew me out to Cairns, and I got to see the Great Barrier Reef. I remember being out there thinking, 鈥淭his is purely because of social media.鈥� It was my first time in Australia, and that was just wild.

I also got media credentials during the Ironman World Championships in 2022. Like, I had a mo-ped and could go along the course 鈥� apparently, even The New York Times had trouble getting that access. That was one of those 鈥渉ow did I end up here?鈥� moments.

Carter: I just literally got home last night from a Zwift event in Mallorca. It was a group of influencers plus people from the Zwift community, who paid to attend. We were there to hype up Zwift and the event. It was really an amazing trip.

Hawkes: I was invited to do Ironman 70.3 in Valencia in a couple of weeks, which is fun. I鈥檝e also done a campaign with for swimsuits made from recycled plastic. Fun collabs pop up here and there, and I try to grab them!

What鈥檚 the end game? Do you see yourself doing this for the long term and continuing to build your brand?

Hawkes: At first, it was just about having fun and creating content. But the more effort I put in, the more I realized there are opportunities to work with others. I think you start to see the benefits of partnerships, so now it鈥檚 definitely a mix of fun and building a business, so I鈥檓 curious to see where it takes me.

Carter: That鈥檚 a great question. I still don鈥檛 know. If it became a full-time thing, that would be incredible. But the thing is, the income can be inconsistent. Some months you get brand deals, and other months, it鈥檚 pretty quiet. So I鈥檓 not sure yet, but I鈥檓 also open to seeing where it goes.

Mulkey: It鈥檚 funny, since I鈥檝e been in this the longest of most folks in the triathlon space, I鈥檝e seen how much you can make as a content creator, and now I鈥檓 not making much at all. I probably need to find another way to make a living, but I grew up with social media, and I can鈥檛 imagine not being part of it. I don鈥檛 know what I鈥檇 do with my phone! If anything, maybe I would step back and take a week off here and there, nothing鈥檚 going to make me walk away. I鈥檓 here for good!

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Ray Zahab first noticed that something was wrong with his body in the spring of 2022. 鈥淚 just started to feel like shit,鈥� he told me, chuckling. The Canadian ultrarunner was 54, and he felt like his body was breaking down. Even his warm up runs began to feel grueling. He was constantly out of breath, napping several times a day, and struggling with severe brain fog. 鈥淚 felt like I had wool in my head,鈥� he said. He wondered if he was nearing the end of his career.

Was this just what aging felt like, or was something worse going on?

Zahab had spent the last two decades crossing some of the most inhospitable environments on Earth. He鈥檚 best known for running over 4,600 miles across the Sahara Desert in 2007, becoming鈥攚ith partners Kevin Lin and Charlie Engle鈥攖he first runners to do so. But if you name an extremely hot or cold place, chances are, Zahab鈥檚 crossed it. The deserts of Atacama, Namib, Patagonia, Gobi, and Death Valley. The frozen tundras of Kamchatka, Baffin Island, Antarctica, and Siberia.

Early in 2022, Zahab and longtime expedition partner Kevin Vallely were stymied while attempting an unsupported crossing of Ellesmere, a 500-mile-long Canadian island in the Arctic Circle (and one of the northernmost land masses on the planet). 鈥淚t was clear after starting northward that the snow conditions were going to make it nearly impossible to pull our heavy sleds,鈥� Zahab said. The men made poor progress, trudging directly into a brutal wind, and Vallely ended up with a condition known as 鈥渃aribou lung,鈥� which Zahab described as 鈥渇rostbite of the lining of the lungs.鈥� They soon threw in the towel.

Now, after failure on Ellesmere, Zahab鈥檚 body was failing him, too. Doctors ran tests, and knew that something was wrong鈥攈is red blood cell count was severely depleted鈥攂ut for several months, they couldn鈥檛 give Zahab a diagnosis. 鈥淚 thought maybe I had long COVID, or parasites left over from a past expedition,鈥� Zahab told me. 鈥淚 wondered if I was maybe just getting older.鈥�

When the results finally came in, they were worse than he鈥檇 imagined.

Zahab had a rare form of lymphoma, a blood cancer, in his bone marrow. He鈥檇 caught it early, and his prognosis was good, but for an extreme endurance athlete like Zahab, already in his mid-50s, it could mean the end of a career.

鈥淢y doctor was like, 鈥楪ood news. We caught this. We don鈥檛 think you鈥檙e going to die. Bad news is there’s no cure for what you got.鈥欌��

But Zahab dove into chemotherapy with the same mentality he took into his expeditions. 鈥淚 had the right, if you will, to sit on the couch, binge Netflix, and just try to make it through the next six months of treatment,鈥� he said. 鈥淏ut I wanted to fight it.鈥�

Each month, Zahab went for a few days of chemo and monoclonal therapy. 鈥淚 would come home, and I’d be sick as a dog for two days,鈥� he recalled. But as soon as he was able, he鈥檇 force himself to get up and out, pushing himself little by little. 鈥淚鈥檇 say, 鈥極k, I’m going to walk a mile one day. The next day I鈥檇 jog a mile. Then I鈥檇 get myself as fit as I could over a 10-day period, and I鈥檇 go away for a week or so to do something personally challenging, whatever that might be for me at the time.鈥�

In between chemotherapy sessions, Zahab ran 30 miles in the Mojave Desert with his daughter. After another session, he crossed a valley in Baffin Island with friends. During another chemo break, he went to the Atacama Desert.

These trips were small potatoes compared to his usual expeditions, but they kept his spirits up. 鈥淚 did these things, not to prove that I could,鈥� Zahab said, 鈥渂ut to try and get myself as fit and stoked and full of life as possible before each round of chemo. I鈥檓 reminding myself that I鈥檓 alive, right?鈥�

Zahab Returns to the Arctic

After six months of chemotherapy, Zahab was in remission. But throughout his treatments, Ellesmere Island never left his mind. And this March, almost three years after their failure in 2022, he and Vallely returned to the frozen island.

They first crossed the island on snowmobiles, burying two caches of supplies, then set out from Eureka, a research base, to ski over 300 miles to the town of Grise Fiord.

The men trudged through blizzards, across frozen sea and land, dragging 150-pound sleds behind them. 鈥淭he surface of the snow was jagged, like little daggers,鈥� Zahab recalled. 鈥淚t felt like pulling something across sandpaper.鈥� They encountered temperatures as low as -112 degrees Fahrenheit with windchill, and winds up to 60 miles an hour. 鈥淲e almost never saw a morning that was warmer than -22 Fahrenheit,鈥� Zahab told me. Zahab鈥檚 tracker suggested the men climbed somewhere between 30,000 and 40,000 vertical feet, hauling their sleds up and down steep dunes of frozen snow known as sastrugi, and endless rolling climbs overland.

When the men arrived and set up camp each night, all of their gear was so cold that touching anything was risky. 鈥淵ou touch the sleeping mat, it鈥檒l give you frostbite,鈥� Zahab recalled. 鈥淵ou touch the air inflation bladder for the sleeping mat, it鈥檒l give you frostbite. Everything was so frozen that I could barely feel my hands.鈥� Zahab got frostbite on his fingertips just from setting up camp inside the tent.

At night, they staked down their tent with custom-made footlong titanium stakes, double-walling it and burying the fly deep in the snow so it wouldn鈥檛 blow away. Polar bears were a constant threat. They staked out a wire fence around their campsites on the ice, tied to shotgun blanks that would fire if bears tripped the line. They slept with neck gaiters over their face, so that the moisture of their breath wouldn鈥檛 freeze their sleeping bags.

The men packed 7,000 calories a day, 鈥渂ut we were burning through it like it was nothing,鈥� Zahab said. Their kit included six liters of olive oil, frozen solid into ice cubes, which they sucked on as they walked to keep their energy up. (By the end of the expedition, they鈥檇 become so adapted to the cold that when the temperatures crested -20掳C鈥攚hich was rare鈥攖hey felt so warm that they stripped down to their long underwear.)

After 28 days they finally reached Grise Fiord, becoming one of the few to have ever crossed Ellesmere Island overland. 鈥淢oney, time, cancer, planning, training, everything, it all paid off,鈥� Zahab said.

鈥淚 Get to Live鈥�

Zahab, who has a side career as a professional speaker and also founded a youth nonprofit, is a walking embodiment of the power of positivity. But he wasn鈥檛 always this way. Until his early thirties, Zahab was an overweight, pack-a-day smoker. He went from never having run a race in his life, to setting speed and distance records in some of the most extreme environments on the planet, all after turning 40.

鈥淔or the first half of my life, I talked myself out of doing things because I was afraid of what might happen, or failing, or what others would think,鈥� he said. 鈥淚n the second half, I decided I was going to make decisions for myself. You never know how many days you’ve got left.鈥�

Cancer, he says, taught him that 鈥渆very moment you have is something to be celebrated.鈥�

鈥淭here was this moment during chemotherapy where I decided that I was going to continue to try,鈥� he recalled. 鈥淭o do whatever I could do to keep living my life as I had before. The cancer wasn’t going to own me. I was going to own it.鈥�

Today, Zahab is 56, and says he鈥檚 in the best shape of his life, but eventually, his cancer may very well return. He remains in remission, but the lymphoma is in his bone marrow, and there is no cure. This doesn’t faze him.

鈥淚 don’t even think about it,鈥� he told me. 鈥淟et鈥檚 say it comes back in a few years鈥� What am I going to do? I can spend my time worrying about that, or I can spend it celebrating. I get to wake up every single day and make an awesome espresso. I get to go see my kids. I get to run, ski, or paddle somewhere. I get to go trail running with my wife.鈥�

鈥淩ight now, I get to live. Why not focus on that?鈥�

The post “I Get to Live.” Explorer Returns to the Arctic After Surviving Cancer appeared first on 国产吃瓜黑料 Online.

Like all great villains, lactic acid has been misunderstood. We鈥檝e been blaming it for the pain we suffer during intense exercise for more than two centuries. There鈥檚 nothing worse, we say, than the 鈥渓actic burn鈥� that locks our failing muscles into immobility. More recent tellings of the story have tried to rehabilitate lactic acid鈥檚 reputation, insisting that it鈥檚 actually trying to fuel our muscles rather than shut them down. But that version 诲辞别蝉苍鈥檛 capture the full complexity, either.

Into this confusion steps , from veteran physiologists Simeon Cairns and Michael Lindinger. It鈥檚 a dense 35-page doorstop titled 鈥淟actic Acidosis: Implications for Human Exercise Performance,鈥� and the clearest conclusion we can draw from it is that the precise causes of muscle fatigue during intense exercise are still a topic of active research and vigorous debate among scientists. But the sudden popularity of baking soda as an acid-buffering performance aid has renewed conversations about how, exactly, lactic acid works in the body鈥攁nd how we might counteract it. Here are some highlights from the latest research.

The Lactic Backstory

The first scientist to draw the connection between exercise and lactic acid was J枚ns Jacob Berzelius, the Swedish chemist who devised the modern system of chemical notation (H2O and so on). Sometime around 1807, he noticed that the chopped-up muscles of dead deer contained lactic acid, a substance that had only recently been discovered in soured milk. Crucially, the muscles of stags that had been hunted to death contained higher levels of lactic acid, while deer from a slaughterhouse who had their limbs immobilized in a splint before their death had lower levels, suggesting that the acid was generated by physical exertion.

A century later, physiologists at the University of Cambridge used electric stimulation to make frogs鈥� legs twitch until they reached exhaustion, and high lactic acid levels. The levels were even higher if they performed the experiment in a chamber without oxygen, and lower if they provided extra oxygen. That finding helped establish the prevailing twentieth-century view: your muscles need oxygen to generate energy aerobically; if they can鈥檛 get enough oxygen, they switch to generating energy anaerobically, which produces lactic acid as a toxic byproduct that eventually shuts your muscles down.

There are two small problems鈥攁nd one big one鈥攚ith this picture. The first detail is that, while lactic acid can be measured in the muscles of dead deer and frogs, it 诲辞别蝉苍鈥檛 actually exist in living humans. In the chemical milieu of the body, what would be lactic acid is split into two components: lactate and hydrogen ions. That鈥檚 not just being persnickety about terminology: lactate and hydrogen ions behave differently than lactic acid would. In fact, they can have separate and sometimes even opposing effects.

The second detail is that lactate (and hydrogen ions) aren鈥檛 really produced because your muscles are 鈥渞unning out of oxygen.鈥� The chemical reactions that use oxygen to turn food into muscle fuel are efficient but slow, great for powering relatively easy and sustained exercise. But they can鈥檛 provide energy fast enough to supply an all-out sprint. For that, you鈥檒l eventually need to rely on lactate-producing anaerobic reactions, even if you鈥檙e huffing pure oxygen from a can.

The big problem with the old view of lactic acid is the idea that it’s a metabolic villain. It turns out that, far from being an inert byproduct, lactate can be recycled into fuel for your muscles. In fact, one of the key superpowers that well-trained athletes develop is the ability to reuse lactate more quickly. This rehabilitation of lactate鈥檚 reputation has been going on for now (though it still has ), but athletes are still left with an unanswered question: if lactate isn鈥檛 what causes muscle fatigue, what is?

What the New Review Reveals

The first thing that Cairns and Lindinger establish is that, yes, levels of lactate and hydrogen ions increase during intense exercise. This is most obvious during intense exercise lasting between about one and twenty minutes. Longer bouts of exercise are less intense, so they can be mostly fueled by non-lactate-producing aerobic energy, and bouts of exertion shorter than one minute simply don鈥檛 have time to produce much lactate.

The evidence is now clear that lactate itself 诲辞别蝉苍鈥檛 interfere in any significant way with muscle function. But lactate and hydrogen ions are produced simultaneously in exactly the same quantities during anaerobic exercise, which complicates the 鈥渓actic acid is a good guy after all鈥� narrative. Lactate may be great, but it comes with an equivalent helping of hydrogen ions鈥攁nd that may be a problem.

When you increase the concentration of hydrogen ions in a solution, you鈥檙e increasing its acidity. That鈥檚 how the pH scale is defined: it鈥檚 a measure of hydrogen ion concentration. During intense exercise, the pH in your fast-twitch muscle fibers (which seem to be particularly susceptible to hydrogen ion buildup) can drop from around 7.0 to 6.0. That change represents a ten-fold increase in the concentration of hydrogen ions鈥攁 situation that can wreak havoc on muscle contraction.

The idea that hydrogen ions are what cause muscle fatigue isn鈥檛 entirely straightforward either, though. When you start hard exercise, the concentration of hydrogen ions actually decreases for about 15 seconds while you use up another source of fast-acting muscle energy called phosphocreatine. And yet your muscles are already getting fatigued during this initial burst, losing some of their maximal force, while hydrogen ion levels are still lower than normal.

There鈥檚 also a disconnect when you stop exercising, or take a break between hard intervals. Hydrogen ion (and lactate) levels keep climbing for a few minutes, which is why the highest lactate levels are generally recorded several minutes after hard exercise. But you don鈥檛 get weaker after you stop exercising; you get stronger as you recover, despite the rising concentration of hydrogen ions. So hydrogen ions may play a role in muscle fatigue, but they can鈥檛 be the whole story.

Another possibility is that hydrogen ions may interact with other molecules to disrupt muscle contraction. The most prominent candidates are potassium and phosphate, both of which increase during exercise and are associated in some studies with muscle fatigue. What these and other candidates have in common is that there are a ton of conflicting results: they have different effects on muscle fibers depending on the level of acidity, the muscle temperature, and the test protocol. This suggests鈥攏ot surprisingly鈥攖hat there isn鈥檛 a single molecule that causes your muscles to lose their power. Instead, it鈥檚 the whole cocktail of things going on inside your muscles during hard exercise that matters.

What About the Burn?

Most of the research that Cairns and Lindinger describe deals with muscle properties: how quickly are your fibers losing their twitch force, and why? It鈥檚 true that, as a middle-distance runner, I鈥檝e sometimes staggered down the finishing straight of a race with the sense that my legs were literally ceasing to function. It鈥檚 an awful feeling to experience, but satisfying to look back on: you know you left nothing out there.

Far more common, though, is a softer limit. You feel a red-hot burn and spreading numbness in your legs, and you choose to back off a bit. This feeling that we used to describe as 鈥済oing lactic鈥� is significant in its own right. In interviews with athletes who鈥檝e begun using baking soda, a common theme is that they鈥檙e able to push harder for longer before feeling that burn in their legs, which in turn enables them to race faster.

One theory about the feeling of going lactic is that you鈥檙e literally starving your brain of oxygen. If you push hard enough, it鈥檚 not just your muscles that go more acidic; your whole bloodstream follows. Thanks to a phenomenon called the Bohr effect, rising acidity reduces the ability of your red blood cells to ferry oxygen from your lungs to the rest of your body, including your brain. In one study, all-out rowing caused oxygen saturation to drop from 97.5 to 89.0 percent, which is a big drop鈥攂ig enough, perhaps, to slow you down and contribute to the out-of-body feeling at the end of hard races.

We also have nerve sensors that keep the brain informed about the metabolic status of the muscles. These group III/IV afferents, as they鈥檙e known, keep tabs on the real-time levels of molecules like lactate and hydrogen ions. If you block these nerves with spinal injections of fentanyl, exercise feels great鈥攖oo great, in fact, because you鈥檒l lose all sense of pacing, go out too hard, then hit the wall.

The most telling finding about the lactic burn, in my view, was where they injected various molecules into the thumbs of volunteers in an attempt to reproduce that familiar feeling. Injecting lactate didn鈥檛 do it. Neither did injecting hydrogen ions, or ATP, a fuel molecule whose levels are also elevated during hard exercise. Injecting them in pairs didn鈥檛 do it either. But injecting all three at the levels you鈥檇 experience during moderate exercise produced a sensation of fatigue in their thumbs, even though they weren鈥檛 moving them. And injecting higher levels turned fatigue into pain.

That鈥檚 a distinction I try to keep in mind in the late stages of hard workouts, and at the crux of races. That burning feeling is real, and it鈥檚 associated with lactate and acidity and muscular fuel levels. But it鈥檚 just a feeling. The lactate and ATP are actually helping me. The hydrogen ions, in combination with various other metabolites accumulating in my muscles, not so much. They鈥檒l eventually stop me. But until they do, I can keep pushing.

***

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For a while, it really looked as though beet juice would beat the odds. Most hot new performance-boosting supplements, even if they claim to be backed by science, don鈥檛 hold up to scrutiny. But after making thanks to high-profile adherents like marathon star Paula Radcliffe, the first wave of high-quality studies supported the idea that beet juice really does improve endurance.

After a decade, though, the bloom had partly faded. There were concerns about its gastrointestinal effects (much as there were with baking soda, another popular endurance-booster), questions about the appropriate dosage, and rising suspicion that beet juice only worked in untrained or recreational athletes but not in serious competitors. These days I rarely hear runners talking about beet juice, and the flow of new studies has tailed off. But a new review takes a fresh look at the accumulated evidence, and concludes that we shouldn鈥檛 be too quick to dismiss the potential benefits of the juice.

Why Beet Juice Might Help

The key ingredient in beet juice, from an endurance perspective, is nitrate. Once you eat it, bacteria in your mouth convert nitrate to nitrite. Then the acidity in your stomach helps convert the nitrite to nitric oxide. Nitric oxide plays a whole bunch of roles in the body. That includes cueing your blood vessels to dilate, or widen, delivering more oxygen to the muscles, faster.

In 2007, Swedish researchers that consuming nitrate鈥攖hat nitric oxide precursor鈥攎akes exercise more efficient, enabling you to burn less oxygen while sustaining a given pace. Two years later, a team led by Andrew Jones at the University of Exeter that you could get a similar effect by drinking nitrate-rich beet juice.

In subsequent years, researchers tested the effects of beet juice on various types of exercise. Crucially, Jones鈥檚 group figured out how to strip the nitrate from beet juice to create an undetectable placebo, and found that athletes improved their performance when given regular beet juice but not nitrate-free beet juice. That made the claims much more convincing. Meanwhile, a company called began selling beet juice with standardized nitrate levels, and eventually added to make the doses more palatable.

When the International Olympic Committee put together on sports supplements in 2018, they included beet juice as one of just five performance-boosting supplements with solid evidence. (The others were caffeine, creatine, baking soda, and beta-alanine.)

What the New Review Found

Over the years, scientists have made numerous attempts to sum up the evidence for and against beet juice. The latest attempt, by a group led by Eric Tsz鈥慍hun Poon of the Chinese University of Hong Kong, is an 鈥渦mbrella review鈥� of nitrate supplementation, mostly from beet juice. It pools the results of 20 previous reviews that themselves aggregated the data from 180 individual studies with a total of 2,672 participants.

The problem with lumping that many studies together is that they measure outcomes differently, use different dosing protocols, and have different study populations. Still, the broad conclusion is that beet juice works鈥攁t least for some outcomes. Most significantly, it improves time to exhaustion: if you鈥檙e asked to run or cycle at a given pace for as long as you can, beet juice helps you go for longer.

On the other hand, there was no statistically significant benefit for time trials, where you cover a given distance as quickly as possible. That鈥檚 the type of competition we care about in the real world, so this non-result is concerning. Time-to-exhaustion tests produce much bigger changes than time trials: a common rule of thumb is that a 15 percent change in time to exhaustion corresponds to about one percent in a time trial. So it may simply be that the studies were too small to detect subtle improvements in time trial performance.

Check out the relative effect sizes for time to exhaustion and time trial in these forest plots. Each dot represents an individual study with its error bar; the farther to the right of the vertical line it is, the greater the performance boost nitrate provided.

Taking the time trial data at face value, the results still look pretty encouraging. They鈥檙e all positive; they just need more participants so that the error bars will get smaller and no longer overlap zero. Of course, eyeballing the data like that is risky because it allows us to draw whatever conclusions we want. But I find it difficult to imagine a scenario where improving your time to exhaustion 诲辞别蝉苍鈥檛 also translate into an advantage in time trials. The two tasks are different psychologically, but they both rely on the same underlying physiological toolset.

Poon and his colleagues also run some further analysis to check whether the dose makes a difference. They conclude that the effects are biggest when you take at least 6 mmoL (just under 400 milligrams) of nitrate per day, which happens to be almost exactly how much a single concentrated shot of beet juice contains. The effects are also maximized when you supplement for at least three consecutive days rather than just taking some on the day of a race.

What We Still Don鈥檛 Know

The big open question that Poon鈥檚 review 诲辞别蝉苍鈥檛 address is whether beet juice works in highly trained athletes. Several studies have found that the effect is either diminished or eliminated entirely in elite subjects. This isn鈥檛 surprising. Pretty much every intervention you can think of, including training itself, will have a smaller effect on people who are already well-trained. This ceiling effect is presumably because elite athletes have already optimized their physiology so thoroughly that there鈥檚 less room to improve.

The flip side of that coin is that, for elite athletes, even minuscule improvements can be the difference between victory and defeat. The size of a worthwhile improvement at the highest level is a fraction of a percent, which is all but impossible to reliably detect in typical sports science studies. For top athletes, the decision of whether or not to use beet juice will have to remain an educated guess for now.

There are other unanswered questions, like whether beet juice is better than consuming nitrate straight. There have been several studies suggesting that this is indeed the case. The theory is that other ingredients in beet juice, like polyphenols鈥攚hich function as antioxidants鈥攎ight act synergistically with nitrate to produce a bigger effect. But as pointed out last year, the evidence for this claim is too shaky to draw any reliable conclusions either way.

Probably the biggest risk in the beet juice data is the preponderance of small studies, some with fewer than ten subjects. It鈥檚 easy to get a fluke result with small sample sizes, and it鈥檚 human nature to get unduly excited about positive results鈥攚hich is why positive flukes often get published more often than negative flukes. So we should remain cautious about our level of certainty.

Despite that caveat, my overall impression is positive. I sent the following summary to Andy Jones, the scientist most associated with beet juice research, to see whether he would agree:

鈥淚t works. It probably works less well in elites, like most things, but there may still be an effect. Higher doses taken for at least a few days in a row probably increase your chances of a positive effect.鈥�

Jones thought that sounded reasonable. He pointed out that there鈥檚 a 聽of evidence emerging that beet juice also enhances muscle strength and power in some circumstances, an effect that Poon鈥檚 review confirms. For endurance specifically, looking at the totality of evidence, Jones figures there鈥檚 a real effect. And he鈥檚 in good company. 鈥淓liud remains a big believer,鈥� he pointed out. That would be Eliud Kipchoge.

***

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As headlines go, 鈥淪ocial Media is Bad鈥� 诲辞别蝉苍鈥檛 raise many eyebrows these days. TikTok and its ilk are said to be harming mental health, stifling creativity, eroding privacy, fueling disinformation, undermining national security, and so on. These are all big issues worthy of careful debate. But there鈥檚 a narrower and more tangible risk that Sweat Science readers might be concerned about. What if social media is making us slower?

A , from Carlos Freitas-Junior of the Federal University of Paraiba in Brazil and his colleagues, presents data on what happens when athletes scroll on their phones before training sessions. Surprisingly, it 诲辞别蝉苍鈥檛 just mess with that specific workout. Instead, over time, the athletes make smaller gains in performance. The findings tell us something about social media鈥攁nd they also suggest that the benefits of a workout may depend in part on the state of mind you鈥檙e in while doing it.

The Problem(s) With Social Media

Several studies over the years have examined social media use in athletes. Most famously, back in 2019 found an association between late-night tweeting (as it was then called) and next-day game performance in NBA players. If the players were tweeting after 11:00 P.M., the players tended to score fewer points, grab fewer rebounds, and shoot less accurately the next day.

You might argue鈥攃orrectly鈥攖hat the problem here is sleep deprivation rather than social media. But have found direct links between the usage of apps such as TikTok and sleep patterns in young athletes, suggesting that the root of the problem is the apps. Researchers have also linked social media use to mental well-being and even eating disorders in athletes, both of which impact performance.

These indirect impacts aren鈥檛 always straightforward: the TikTok-hurts-sleep study also found that Instagram usage was associated with greater calmness, for example. But there鈥檚 also a more immediate concern, which is that social media apps leave you mentally fatigued, which in turn directly compromises your endurance and decision-making abilities.

The Mental Fatigue Debate

The study that kicked off the modern conversation about mental fatigue in sport was a 2009 experiment from a researcher named Samuele Marcora. He showed that 90 minutes of doing a cognitively challenging computer task by about 15 percent compared to spending 90 minutes watching a documentary.

More studies followed, each investigating different types of mental fatigue and their effects on different types of athletic performance. Many of them echoed Marcora鈥檚 original results, but . One of the big unresolved questions is the extent to which the findings apply in real life. If you have to write an exam or do your taxes right before you run a marathon, that鈥檚 probably bad news. But what about the normal activities we engage in on a daily basis鈥攍ike scrolling through the social media apps on your phones? Do they induce sufficient mental fatigue to affect performance?

Back in 2021, found that 30 minutes of social media use hurt athletes鈥� times in 100- and 200-meter freestyle trials, but not in the 50 meters. found that boxers made worse decisions after using social media, but that their jumping performance was unaffected. found no effect of social media use on strength training performance. These results are consistent with the general pattern of research on mental fatigue and related stressors like sleep deprivation: with sufficient motivation, you can still exert maximal force, but your decision-making and endurance may be compromised.

What the New Data Shows

Freitas-Junior鈥檚 new study looks at volleyball players, testing their jumping performance and their 鈥渁ttack efficiency,鈥� a measure of how hard and how accurately they can hit the ball in a sequence of attacks. What鈥檚 different about the study is that it looked at long-term rather than immediate effects. Fourteen athletes spent half an hour before practice either using Facebook, WhatsApp, and Instagram on their phones, or watching documentaries about the history of the Olympics. After three weeks, their performance was assessed and then they switched groups and repeated the process for another three weeks.

At the end of the three-week period, jumping performance wasn鈥檛 affected under either condition, but athletes鈥� attack efficiency was worse following the three weeks of social media use. The difference was statistically significant, but to be honest the data isn鈥檛 very convincing.

For starters, take a look at the mental fatigue data. This shows how much, on average, mental fatigue (on the vertical axis) increased after watching the documentary (DOC) or using social media (SMA):

This is nice clean data. Watching the documentary increased the subjective perception of mental fatigue in almost every individual. Using social media increased it even more, again with uniform results in all the individuals. We can say with confidence that social media use increases mental fatigue compared to chilling with a doc.

Now take a look at the attack efficiency data, measured in arbitrary units where a higher number is better:

This time the individual data is all over the map. The statistical analysis tells us that, on average, the social media group got worse while the documentary group got better. This average effect may or may not be real鈥攐nly more and larger studies can confirm if it is. Based on the body of previous research, I鈥檇 guess that it鈥檚 probably real. But the pattern is so inconsistent on an individual level that I鈥檇 hesitate to use it as a basis for advice to athletes. Some athletes got better after social media use. That might be a fluke, or it might indicate that they have a healthier relationship with their apps such that a little phone time before practice gets them in a better headspace.

In the end, then, the narrative isn鈥檛 as tidy as we might like. It鈥檚 not that social media is uniformly bad, will leave you mentally fatigued, and will automatically rob you of training gains. There鈥檚 still a valuable message here, though. The things we do鈥攕ocial media, yes, but also real-world socializing, reading a book, listening to music, working, commuting, daydreaming, and so on鈥攁ffect our mental state and readiness to perform. We all respond to these things differently, so there鈥檚 no universal list of dos and don鈥檛s. But it鈥檚 worth figuring out what gets you in the right headspace and leaves you mentally energized, so that you can replicate it when it matters.

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The course has won the 2025 Barkley Marathons.

Or really, we should say the winner is race founder . For the first time since 2022, there are no finishers at the Barkley Marathons. Three-time finisher John Kelly completed loop three in 39 hours, 50 minutes, and 27 seconds in the wee hours of Thursday morning, Barkley Marathons Chief Resident Tweeter (or should we now say, Xer?) .

In doing so, Kelly dipped under the cut-off by 10 minutes to earn a 鈥渇un run鈥� before tapping himself out. The course, which some believe included a new nasty 45-minute section to this year, was just too hard. Only two other runners made it onto loop three, Tomokazu Ihara (Japan) and S茅bastien Raichon (France.) Raichon returned to camp five minutes later without completing the loop. Two hours later Ihara returned, well beyond the cut-off.

The 2025 Barkley Marathons is over. There are no finishers.

鈥� Keith (@keithdunn)

While we鈥檙e disappointed that we鈥檙e robbed from 20 more hours of entertainment, really, we can all breathe a sigh of relief:

The Barkley Marathons can rightfully maintain it鈥檚 moniker as 鈥渢he world鈥檚 hardest race.鈥�

It鈥檚 the 25th time in 40 years that the Barkley Marathons has no finishers. Only 20 people total have ever done it. The 40th edition is the least 鈥渟uccessful鈥� (or should we say most successful?) since 2018, when similarly just one runner, Gary Robbins, completed a 鈥渇un run.鈥�

Kelly, who鈥檚 on a quest to tie Jared Campbell鈥檚 record of four finishes, will just have to come back again next year, armed with even more experience and grit.

Wondering what the Barkley Marathons is all about? Head over to our to learn about everything the rules, the course, the history and lore, and why an event that sounds an awful lot like orienteering actually isn鈥檛 orienteering at all.

Welcome to the 2025 Barkley Marathons

For those in the nichest of niche ultrarunning circles, Christmas came early. At 11:37 A.M. Eastern on Tuesday, March 18, the 2025 Barkley Marathons began.

The start date and time of this race that鈥檚 as fabled as it is mysterious change every year. But the third week of March is historically early. Perhaps race founder and his successor, Carl Laniak, were hopeful that pushing the event into the middle of March would bring colder, wetter, windier, and all-around grosser weather. After all, . And, ostensibly, they simply can鈥檛 let that happen again.

But if they were looking for miserable weather, the weather gods had their own tricks up their sleeves. A cold but clear Monday night gave way to a sunny Tuesday morning with temperatures projected to reach into the high 60s or even the low 70s, according to . That鈥檚 pretty damn perfect, for the runners anyway.

Of course, Laz and Laniak have other curve balls they can throw in the runners鈥� way. The biggest one, of course, is simply to make the course even harder. While the race is always five 20- to 26-mile loops and runners always have 13 hours and 20 minutes to complete each loop and 60 hours to complete the whole event, the course itself changes every year. But you can always expect a lot of nasty hills, prickly briars, and off-trail shwacking for a total of 120-130 miles and 60,000 feet of gain. No course markings, and no GPS devices allowed. Runners claimed last year鈥檚 edition was bramblier than ever, and yet more runners than ever rose to the challenge.

Here are our live updates from the 2025 Barkley Marathons, in reverse chronological order:

40 Hours Elapsed: The Course Wins

Kelly tapped himself out after earning a 鈥渇un run.鈥� Raichon returned to camp five minutes later in 39:55, but did not complete loop three, . Ihara made it back to camp two hours later.

Why did Kelly quit? With just 20 hours and 10 minutes left to run the final two loops after finishing loop three, time鈥�and any modicum of sanity鈥�was not on his side. When Kelly successfully finished the Barkley Marathons last year his splits on the final two loops were 14:10 and 13:30, respectively. We have 40 years of data showing the compounding effects of sleep deprivation, exhaustion, and delirium magnify exponentially over the final two loops at this race.

While in past years finishers have had some time to recoup in camp between loops, if they so chose, this year鈥檚 particularly brutal course forced runners fast enough to complete a loop in time to essentially head straight back out. Kelly spent less than 10 minutes in camp between loops two and three.

For the first time since 2022 and for the 25th time in 40 years, the Barkley Marathons has no finishers. The course (and let鈥檚 be honest, Laz) has won.

39:50 Elapsed: John Kelly Completes a 鈥淔un Run鈥�

Kelly was the first to return to camp. He arrived through the swirling wind and darkness at 3:28 A.M. on Thursday, . That鈥檚 just 10 minutes under the cut-off for earning a 鈥渇un run鈥� (completing three loops in under 40 hours).

Who鈥檚 Left in the 2025 Barkley Marathons:

• Tomokazu Ihara (Japan)鈥�on loop three. This is his sixth attempt. Ihara, 47, has run numerous ultras and is a coach and race director. In 2023 he won the 鈥淕rand Slam of Ultrarunning,鈥� meaning he had the fastest cumulative time at five 100-milers in one summer: the Old Dominion 100, Western States 100, Vermont 100, Leadville 100, and Wasatch 100.
• John Kelly (U.S.)鈥�on loop three. This is his eighth attempt. Kelly, 40, is a three-time Barkley Marathons finisher, making him the second-most finisher behind four-time finisher Jared Campbell. He also has a Ph.D. in electrical learning and machine learning and is the Chief Technology Officer at Envelop Risk and has set several high-profile fastest known times, including on the Pennine Way and the Long Trail.
• S茅bastien Raichon (France)鈥�on loop three. This is his second attempt. Raichon, 52, 聽has finished Tor des Geants (2019) and set the GR20 FKT last year.

27 Hours Elapsed: Maxime Gauduin Quits

The Frenchman called it quits on loop three with no pages in tow, at 2:56 P.M. Eastern. And then there were three.

25:29 Elapsed: 4 Runners Total Have Finished Loop 2

Frenchmen S茅bastien Raichon and Maxime Gauduin finished loop two together in 25:29, with an hour and 11 minutes to spare, .

Meanwhile, after just 10-ish minutes in camp John Kelly (U.S) began loop three about 90 minutes before the cutoff. Raichon and Gauduin followed suit about 30 minutes later. There are now four runners on loop three, with Tomokazu Ihara (Japan) in the lead.

Beginning Loop 3.

鈥� Keith (@keithdunn)

25 Hours Elapsed: We Have 2 Loop 2 Finishers (Phew)

Tomokazu Ihara (Japan) finished loop 2 in 24:32, and the collective Barkley community took a sigh of relief. He began loop three just 15 or so minutes later, . Three-time Barkley finisher John Kelly (U.S.) finished loop two on 25 hours on the dot (and 40 seconds, but who鈥檚 counting). That鈥檚 five and a half hours slower than Kelly鈥檚 overall split through loop two last year, when he went all the way.

Both Ihara and Kelly split over two hours slower for loop two than loop one, which is pretty in line with the discrepancy between loops one and two in previous years. However, their loop two splits of roughly 12:35 and 13 hours, respectively, are about two hours slower than Kelly鈥檚 loop two split last year.

They have until 40 hours elapsed to make it back to the gate in time for a 鈥渇un run鈥� (three loops). That means they need to run faster than 14 hours for the third lap. Last year Kelly completed loop three in 12 hours, with the company of Ihor Verys and Damian Hall.

24 Hours In and No One Has Completed Loop 2

With the latest drop (Julien Chable from France), only six runners remain, . They have until 26:40 elapsed to return to the yellow gate and head back out on their merry (or should we say weary) way if they want to have any chance of completing a 鈥渇un run鈥� (three loops), much less the whole thing (five loops).

For context, 12 runners completed loop two in under 24 hours last year. The one runner to complete loop two in longer than that (Guillaume Calmettes, France, 26:25) made it to a fun run before tapping out. All five of last year鈥檚 finishers finished loop two in under 20 hours. And that includes Jasmin Paris, who finished the whole race with less than two minutes to spare.

Will the runners be able to pick up the pace now that they (theoretically) know the new course? Or will the alternating of loop directions, shifting from daylight to darkness, and compounding effects of sleep deprivation, fatigue, and frustration get the best of them?

We鈥檙e hoping for the former, but expecting the latter.

(And side note: the last time no one completed a 鈥渇un run鈥� was in 2006!)

21:00 Elapsed: 7 Runners Remain on Loop 2

Chris Fisher (U.S.) and Thomas Calmettes (France) both dropped from loop two at Bald Knob this morning, , noting, 鈥淭hough seemingly about a hundred yards apart, they did not see each other.鈥� This means at most 7 runners will successfully finish loop two within the time limit and move onto loop 3. That鈥檚 down from 13 who finished and 12 who moved onto loop three last year.

13:20 Elapsed: 10 Runners Complete Loop 1 Within Limit

That includes a final runner who finished the loop with under two minutes to spare, . They were able to do one of Barkley鈥檚 fastest-ever camp stops and turned it around in time to start loop two before the 13-hour-and-2o-minute cut-off.

Of those 10 runners, nine went on to loop 2, . Fourteen runners returned to camp, and a 16 remain out on the course. When they returned they will also receive a DNF and be ceremoniously dismissed from the race with the playing of 鈥淭aps鈥� on the bugle.

This means that there was just a 25 percent loop-one finish rate within the cutoff this year. That鈥檚 exactly half of what it was last year, when 20 of the 40 entrants finished loop one in time. What鈥檚 going on this year?

Some runners may have adopted the old 鈥渇ollow a veteran runner鈥� strategy, , maintaining that Laz was 鈥渘ot impressed鈥� by this game plan. We鈥檙e also hearing grumblings that Laz added a 鈥渧ery tough section鈥� that could add a whopping 45 minutes to each loop this year.

We鈥檙e also receiving reports that there are 16 books that runners must reach on every loop this year. If true, that鈥檚 at least one more than the typical 10 to 15.

11:00 Elapsed: Will It Be a Short Barkley This Year?

A third runner finished loop one in 10:20 elapsed, according to Dunn. Laz that 鈥渆very loop is easier than the loop before鈥� as he set out for loop two, which per tradition will be run in the opposite direction and also in the pitch black, about 20 minutes later. Ah, Laz, we鈥檝e missed your sense of humor!

snuck in under the 11-hour mark in 10:57:32 and 10:57:50, which means only five runners have finished loop one with one hour remaining before all runners left in the race must start loop two. The odds (and what seems to be an especially tough course, given the bluebird conditions today) do not appear to be in the runners鈥� favor this year.

Dunn that 鈥淭omo,鈥� otherwise known as Tomokazu Ihara (Japan), is one of the successful handful onto loop two.

9:45 Elapsed: Two Runners Complete Loop 1

They finished the loop in 9:44:55 and 9:44:57, . For reference, nine athletes completed loop one in well under nine hours last year. Given that we know of at least one (and we think more) Barkley finisher who was in that group of nine last year, signs are pointing to a very, very hard course this year.

Buckle up.

6:00 Elapsed: The DNFs Start Rolling In

Less than six hours into the 60-hour race and the 2025 Barkley Marathons already has its first drop. The first runner to quit the race returned back to camp on 鈥渜uitter鈥檚 road鈥� in the early evening, at 5:21 P.M. Eastern on Tuesday. They faced a rendition of 鈥淭aps鈥� played on the bugle horn, and with that their race ended. They made it about five miles in those six hours, Dunn said.

The second DNF followed just over an hour later. They made it about seven miles in seven hours, . An hour later and the DNF rate had doubled.

鈥淭he thing is, they are coming back to camp from all directions and in some cases cannot describe where they were,鈥� . 鈥淭his is old school Barkley.鈥�

鈥淔or as bad as you guys make it sound, it is worse.鈥� 鈥� a runner

鈥� Keith (@keithdunn)

For the first time, runners must return their race-issued analog watch when their race ends, .

11:37 A.M.: The 2025 Barkley Marathons Have Begun

After the classic 鈥渂rief memorial鈥� in which he cautioned runners to 鈥渕ake your peace with God,鈥� Laz lit the cigarette marking the start of the 2025 Barkley Marathons. Runners have 13 hours and 20 minutes to complete the loop and make it back to the yellow gate marking the entrance to Frozen Head State Park. That means we better see them all back there by 11:37 P.M. so they can begin their first night loop.

Who鈥檚 racing? We鈥檒l have to wait to find out until runners finish a loop鈥r two鈥r three, otherwise known as a 鈥渇un run.鈥� But Dunn outed three-time finisher John Kelly when the conch (eventually) was blown:

鈥淔inally,鈥� Kelly . 鈥淲e could have done a loop by now.鈥�

If Kelly, who was one of the five to finish last year, prevails again he will join the exceedingly rarified air of becoming just the second person ever along with Jared Campbell to finish the Barkley Marathons four times.

10:38: A.M.: The Conch Has Been Blown (Finally)

Technology鈥�namely online campsite reservation systems鈥�is making it increasingly challenging for Barkley custodians to keep the start date of this mystical event a secret. And sure enough, online grumblings came to fruition on Tuesday morning. At 10:38 A.M. Eastern after 鈥渕any failed attempts,鈥� Carl Laniak blew the conch marking one hour until the start of the 2025 Barkley Marathons.

After multiple failed attempts, the conch was blown at 10:37. The 2025 Barkley Marathons begins in one hour. .

鈥� Keith (@keithdunn)

Why didn鈥檛 race founder Gary 鈥淟azarus Lake鈥� Cantrell blow the conch?

鈥淏ecause he鈥檚 even worse than Carl at blowing it,鈥� Dunn (鈥渪鈥�-别诲?).

There鈥檚 probably at least some truth to that statement. For those who haven鈥檛 had the pleasure of trying, cajoling sound out of a big shell isn鈥檛 easy. But fans of this cult classic event are also wondering if it鈥檚 a sign of changing times. Laz, 69, has slated 聽Laniak as his successor to overseeing the Barkley Marathons.

We鈥檒l have the next 60 hours to find out. One hour until the race begins.

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Seven miles into the 2004 Cherry Blossom Ten Miler in Washington, D.C., a few months before that summer鈥檚 Olympic track trials, I felt a strange pop in my lower back. Hobbling gingerly to a halt, I realized that my race was over. As it turned out, so was my track career. I鈥檇 suffered a stress fracture in my sacrum, the bone that connects your lower back to your pelvis. It鈥檚 an unusual injury, and in the months that followed, I puzzled over my fate. Had I been wearing the wrong shoes, or logging too many miles, or not stretching enough? It wasn鈥檛 until a decade later that I began to consider another possibility: perhaps I hadn鈥檛 been eating enough.

, the International Olympic Committee unveiled something it called 鈥渞elative energy deficiency in sport,鈥� or REDs. The link between eating disorders, missed periods, and weakened bones was already widely known as the 鈥渇emale athlete triad.鈥� But REDs adopted a broader view. Failing to get enough calories to fuel both normal metabolism and the rigors of training were associated with a wide range of problems in 14 categories: not just poor bone health (it turns out that a stress fracture in the pelvis or sacrum is considered a primary indicator of REDs), but also impaired immune function, digestive issues, disrupted sleep, even urinary incontinence. The syndrome could afflict men as well as women, and it wasn鈥檛 limited to athletes with eating disorders. Some who鈥檇 been struck by it simply didn鈥檛 realize they weren鈥檛 getting enough calories to support their training.

The diagnosis caught on. The most recent , from 2023, pooled data from 178 studies involving more than 23,000 participants. It concluded that anywhere from 15 to 80 percent of athletes have REDs, depending on the sport. The problem is more common among women, and most prevalent in endurance sports like running, where weight affects performance. But not everyone is convinced that REDs should be applied so broadly. , penned by eight prominent sports scientists, poses a provocative question: Is REDs even real?

The piece鈥檚 lead author is Asker Jeukendrup, the Dutch Olympic Committee鈥檚 top nutritionist and a former head of the Gatorade Sports Science Institute. He and his colleagues take a deep look at the evidence underpinning REDs. The studies they examine are mostly short-term and observational, making it impossible to prove that calorie shortage causes the symptoms described. And in practice, measuring how many calories a person consumes and how many they burn is so error-prone that it鈥檚 impossible to say with confidence who is or isn鈥檛 coming up short. As a result, they conclude, estimates of REDs鈥檚 prevalence should be considered highly suspect.

Despite these shortcomings, 鈥淩EDs has become a much-discussed topic on social media and in mainstream media news outlets,鈥� the authors note 鈥攖o such a degree, they argue, that calorie shortage has become a convenient scapegoat for whatever problems athletes face. Jeukendrup and his colleagues suggest replacing the diagnosis with an alternative framework incorporating eight potential triggers: training, nutrition, disordered eating, sleep, infection, mental health, life/environmental, and undiagnosed clinical conditions. Any of these factors, alone or in combination, can cause a constellation of symptoms resembling REDs.

Meanwhile, out in the real world, some of the nuances of that message are getting lost. 鈥淭he title of the paper鈥斺�楧oes REDs Exist?鈥欌�攎akes for a shocking headline that can be easily shared but 诲辞别蝉苍鈥檛 fully reflect the content,鈥� says Megan Roche, a running coach whose doctoral work included research on low energy availability, hormones, and bone health in ultrarunners. Suddenly, she鈥檚 fielding tough questions from athletes and podcast listeners, few of whom have engaged with the details of the 11,000-word scientific review. Persuading athletes to seek help for REDs can be challenging at the best of times, she says; confusing them about whether a condition is even a thing only makes it harder.

The scientists who developed the original set of guidelines for REDs are also befuddled. They never intended to suggest that all training and health problems are the result of calorie shortage, or even that it should be the default assumption. Their are explicit that the signs and symptoms noted can be caused by other triggers. In other words, there鈥檚 nothing straightforward about any of this. 鈥淭here鈥檚 never going to be a 鈥榩regnancy test鈥� for REDs,鈥� says Trent Stellingwerff, a physiologist at the Canadian Sport Institute Pacific who helped author the IOC鈥檚 most recent REDs guidelines. 鈥淟ife is not binary. Disease is not binary. Clinicians have to make decisions based on incomplete information every day.鈥�

Much of the debate seems to be about messaging: Are the risks associated with calorie shortage getting too much attention? But there are some specific points of disagreement, like whether athletes who don鈥檛 otherwise show signs of disordered eating might sometimes slip into calorie shortage without realizing it. Meanwhile, Roche sees REDs crop up in athletes during times of stress or lifestyle transition鈥攆reshmen in college taking on a heavier training load, new mothers adjusting to altered schedules and the caloric demands of breastfeeding.

Which brings me back to that stress fracture. I was a hearty eater throughout my track career, but I increased my mileage substantially in 2003 and 2004, adding regular two-a-day runs for the first time. My weight decreased, and my BMI dropped below 18. It鈥檚 impossible to know exactly what led to my fracture, and it鈥檚 clear that REDs as a diagnosis will continue to evolve. We may eventually get a better understanding of how calorie supply interacts with risk factors like training load and stress. But I can鈥檛 help but wish that someone had been beating the drum about risks from inadequate fueling鈥攅ven in athletes who never turn down seconds, and even for men鈥攂efore I hit empty.

For more Sweat Science, join me on and , sign up for the , and check out my forthcoming book .

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Everyone has a plan, Mike Tyson famously said, until they get punched in the face. The endurance athlete鈥檚 version of that dictum might be: everyone has a great VO2 max and an efficient running stride until they鈥檝e run 20 miles. How you fare in those final miles depends, in large part, on how steeply these factors have declined over the course of the race.

This is the fundamental premise of 鈥渇atigue resistance,鈥� an idea I first wrote about back in 2021 that is currently one of the hottest topics in endurance science. The old view was that you could run some lab tests to determine an athlete鈥檚 VO2 max, lactate threshold, and running economy (or an equivalent measure of efficiency for other sports) and calculate their predicted finishing time. The new insight is that these factors change as you fatigue鈥攁nd crucially, they change more in some people than others. Having good fatigue resistance, then, is the 鈥�fourth dimension鈥� of endurance.

So far, most of the research on fatigue resistance鈥攚hich is also called 鈥渄urability鈥� or 鈥減hysiological resilience鈥濃�攈as focused on demonstrating that it plays a role in determining who wins races. What we really want to know, of course, is how to improve it. That鈥檚 the question a pair of new papers tackles.

The Case for Strength Training

The first study, by Michele Zanini and his colleagues at Loughborough University in Britain, tests a twice-a-week strength training program in 28 well-trained runners with an average 10K best of 39 minutes. Half of them added the strength routine to their usual training for ten weeks, while the other half just carried on with their usual training.

The performance test was a 90-minute run at a pace near lactate threshold, followed by an all-out time-to-exhaustion test that lasted about five minutes. Every 15 minutes during the 90-minute run, they measured running economy, which quantifies how much energy you burn to sustain a given pace. They expected running economy to get worse as the runners fatigued, but wanted to find out whether strength training could counteract this deterioration.

The results were encouraging. Before strength training, running economy got 4.7 percent worse after 90 minutes of running; after strength training, it only declined by 2.1 percent over the same period of time. Here鈥檚 how running economy changed over the course of the run, with white circles showing the baseline test and black circles showing the post-strength-training test:

Note that a positive change (i.e. the line drifting upward) means that the runners were burning more energy to maintain the same pace as time went on. In the baseline test, running economy starts getting significantly worse after about an hour. After strength training, this drift is less pronounced.

The strength training program in the study consisted of a mix of heavy weights and explosive plyometrics. The resistance exercises were the back squat, single-leg press, and seated isometric calf raises, typically with around three sets of six reps. The plyometrics included vertical exercises (pogo jumps and drop jumps) and horizontal exercises (hops and bounding). It鈥檚 not clear from this study whether the heavy weights or the plyometrics provided the magic, though Zanini that both methods have produced similar results in previous studies of strength training and running economy.

Why does strength training improve fatigue resistance? Here we鈥檙e limited to speculation. It may have something to do with making fast-twitch muscle fibers more efficient, or making tendons stiffer and springer, or improving strength sufficiently to maintain good running form for longer.

Other Options for Boosting Fatigue Resistance

The other new paper is by Andy Jones of the University of Exeter in Britain and Brett Kirby of the Nike Sport Research Lab. Jones and Kirby played key roles in Nike鈥檚 Breaking2 Project in 2017, where they encountered what you might call the Zersenay Tadese Problem. Tadese had exceptional lab values, including the best running economy ever measured, but repeatedly struggled at the marathon distance, while his teammate Eliud Kipchoge had relatively modest lab values but turned out to be the dominant marathon runner of the decade. The difference, presumably, was that Kipchoge had better fatigue resistance.

The new paper sums up their thoughts on fatigue resistance, including some speculation on how to improve it. Strength training, they note, is one option鈥攖hough they point out that few of the East African runners who currently dominate international marathoning do structured strength training.

Overall, their view seems to be that the best ways of improving fatigue resistance are mostly the things that endurance athletes already do to get better: high mileage, especially accumulated over many years; long runs, including some sections at close to race pace; intense interval sessions; following a pyramidal training distribution. There may also be some more subtle effects from, for example, doing some fasted training or living at high altitude. None of these are uniquely targeted at fatigue resistance.

Jones and Kirby do mention one other possibility: put on some supershoes. There鈥檚 likely an instant effect, since the heavy cushioning reduces muscle damage and enables you to keep striding smoothly through the later stages of a marathon. And there may also be a chronic effect: the cushioning allows you to absorb and recover from higher levels of training, enabling you to safely rack up higher mileage and thus improving your fatigue resistance over time.

The overall impression, then, is more evolution than revolution. All these years, we鈥檝e been training to maximize VO2 max, running economy, and threshold. Now we鈥檝e got a new target鈥攆atigue resistance鈥攂ut so far the best ways of improving seem to be mostly the things we鈥檙e already doing. Even Zanini鈥檚 strength-training routine is the kind of thing coaches and scientists already recommend. But if you have the sense that fatigue resistance is one of your weaknesses, you now have extra motivation to move strength training and plyometrics from the 鈥淚 should do this鈥� column to 鈥淚鈥檓 doing it.鈥�

For more Sweat Science, join me on and , sign up for the , and check out my forthcoming book .

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