OTS can afflict anyone who takes a more-is-more approach to their sport.
OTS can afflict anyone who takes a more-is-more approach to their sport. (Photo: lzf/iStock)

The Mysterious Syndrome Destroying Top Athletes

OTS can afflict anyone who takes a more-is-more approach to their sport.

A while back, Outside contributor Meaghen Brown noticed a strange phenomenon among the elite ultrarunners that she was training with. Runners would come on the scene, win races and smash records, and then a few years later succumb to a mysterious ailment that left them a shadow of their former selves. Top athletes were suddenly lethargic, depressed, and unable to train, and doctors couldn’t tell them why. Their problem, it turned out, was overtraining syndrome, or OTS. One researcher called it “the scariest thing I’ve seen in my time studying athletes.” And it’s not just runners that are at risk. In this episode, we look at how OTS can afflict anyone who takes a more-is-more approach to their sport.

Podcast Transcript

Editor’s Note: Transcriptions of episodes of the Outside Podcast are created with a mix of speech recognition software and human transcribers, and may contain some grammatical errors or slight deviations from the audio.




Outside Podcast Theme: From Outside Magazine and PRX, this is Sweat Science, stories of human endurance.

Peter Frick-Wright (host): A few years ago, journalist Meaghen Brown started noticing something strange in her local ultra running community.

Meaghen Brown: I had a couple of friends who were struggling with something that seemed kind of unplaceable. Basically they would do really, really well for like two or three years and then totally fall off the map.

Frick-Wright: Meaghen was working at Outside, living in Santa Fe, and hanging around with elite runners, and these guys were mysteriously slipping down the ranks, right when they should have been at the top of their game.

Brown: You have a really successful athlete who's like top of the podium breaking records for about two years, maybe three, and, all of a sudden, they're not. It’s not stomach, it's not an injury. It's just they don't seem capable of performing at the same level anymore.

Frick-Wright: And then they just disappear from the sport.

So Meaghen started poking around asking the runners she knew if they'd felt or observed similar loss of ability.

Brown: And a few of them said yes. A few of them pointed me in the direction of some runners dealing with this.

Frick-Wright: A strange fatigue  was infecting the ultra running community like a virus leaving runners confused with symptoms that seemed all over the place.

Brown: These bizarre sort of leg cramps, loss of appetite, diminished libido, weird heart arrhythmias, debilitating staleness in your legs.

Frick-Wright: Some runners would just try to push through it, convinced their poor performances meant they weren't training hard enough. Others would lay off for a few days or a week, but nothing seemed to work. Wworse, no one really felt like they could talk about it. And most doctors could only shrug. After all, they're still running 80 miles a week. Test results are all coming back negative. How sick could they really be?

Meaghen kept digging and, in 2016, published an article in Outside called Running on Empty, which explored not only who was falling to this mystery ailment, but why. She discovered it had a name: overtraining syndrome.

Brown: One of the exercise researchers that I spoke to, you said it's the scariest thing that he's ever seen, like in his years of studying athletes.

Frick-Wright: At its most basic, overtraining syndrome or OTS, seems pretty straightforward. Go too hard for too long without enough rest and things start to go wrong. Ignore the signs and keep pushing and things start to go catastrophic.

But that explanation belies a question that has confounded researchers for decades. Basically, no one really knows what's happening to tip an athlete over an edge that they can't recover from.

Alex Hutchinson: There's a ton of research out there on over-training and there's been dozens and dozens and dozens of studies, at least going back to the nineties.

Frick-Wright: This is Outside columnist, Alex Hutchinson, our guide throughout the Sweat Science series.

Hutchinson:The reason it seems like there isn't a lot of research on it is that none of it reaches any good conclusions. It's not that this is some new thing that has just emerged. It's just that we still don't really know a lot about it, but people have been trying to figure out what overtraining is for for quite a long time now.

Frick-Wright: So OTS is sort of a boogeyman for endurance athletes, a ghost of a sickness that leaves you a shadow of your former self with few answers and fewer options. And while Meaghen first noticed OTs in the ultra running community, those aren't the only athletes it can affect. Anyone who's seriously devoted to their sport, who takes a more is more approach to training, and constantly pushes to the edge, might come to find themselves completely inexplicably fatigued. And what do you do when your whole life has been about competing at an elite level and suddenly you don't have the energy to pull yourself out of bed.

To tell that story, I'm going to hand things off to producer Robbie Carver, and to learn more about what happens to the body during OTS, we're going to stick with our habit of diving into an obscure sport you may not be all that familiar with.

Corrine Malcolm: So the sport of biathlon pairs cross country skiing, so this high aerobic- and anaerobic-demand sport, with marksmanship. Or in the case of biathlon, shooting a 22.

Robbie Carver: This is Corrine Malcolm, former racer for the U.S. national biathlon team.

Malcolm: It's very popular in the U S every four years when we see it on TV during the Olympics and we're like, wow, that's really cool. I love seeing it grow in popularity every four years and the like fade into the background again.

(fade in music from biathlon game)

Carver:The biathlon originated in Scandinavia where soldiers prided themselves on their ability to shoot accurately while on skis. There's a few different types of events, but basically competitors skate-ski as fast as they can around a course with a rifle attached to their back. And every time they complete a lap, they ski into a gun range and attempt to shoot down targets, each a little larger than the diameter of a golf bat. Miss a target, get a penalty, either a fixed time or a penalty loop you have to ski before getting back onto the main course.

Malcolm: So you have to not only be an incredibly good skier but you also have to be able to settle down quickly enough on the range to be a fast and accurate shooter.

Carver: It's all out physical intensity paired with precision motor skills, and, arguably, the most demanding endurance sport in the winter Olympics. Imagine sprinting as hard as you can and then immediately trying to thread a needle on your first try.

Malcolm: The goal is to just be so efficient and so smooth and have it just be clockwork. Cause you want to be on the mat and off the mat in 25 seconds, which is crazy.

Carver: Corrine began skiing when she and her family moved to Hayward, Wisconsin just as she was beginning high school. She fit right in, and, like lots of motivated high school kids, was doing a bit of everything: choir and band, musicals, and both running and cross country skiing.  And really, she was a mediocre skier at best, more bull in a China shop than graceful Swan. But then in the summer before her junior year, she attended a training camp with the Olympic development group and that changed everything.

Malcolm: I walked out of that camp, like convinced that I was going to make an Olympic team, and skiing was the only thing that mattered.

Carver: For many of us, that kind of teenage conviction would have lasted about as long as our first crush, but not Corrine. That year, she studied abroad in Latvia to train for 10 months with their Olympic ski coaches. When she returned to the U.S., she crushed it, winning the Wisconsin state meet, making the junior national team, and receiving All American honors at the camp. Then after two years skiing for Montana State University, she was approached by a junior development coach for the U.S. Biathlon.

Malcolm: He was like, you're skate skiing really well, do you think you could shoot a gun? And I was like, I don't know, like maybe. And he's like, well, why don't you try?

Carver: So Corrine dropped out of college and drove to Fort Kent, Maine where the U.S. Junior Development Biathlon Team was training.  For the first time in her skiing career,Corrine had to do but train. She learned how to shoot a rifle, how to ritualize her breathing to steady her heartbeat before a shot.

Malcolm: So you go (breathes in and out) and it's on that cutoff exhale that you then kind of take that next shot in.

Carver: And under the watchful eyes of careful coaches, her skill improved rapidly.

Malcolm: I won Junior National Trials, which meant that I had a paid spot on the Junior National Team to go to Junior Worlds.

Carver: By the end of that winter, she was named to the Senior National Team. She moved to the Olympic Training Center in Lake Placid, New York and became the team's youngest member. The risks she took dropping out of school to pursue skiing full time had paid off.

Malcolm: I felt like I had taken that next step on the pipeline and dove in headfirst, was like so gung ho to make a good impression, to prove that I had earned my spot on the team.

Carver: This should have been the moment in Corrine's story where everything came together and she flourished. Her hard work, dedication and willingness to risk it all pain off with a spot in the Olympics just a few years away. But instead, this is the moment where the clouds started gathering and the skies began to darken and it began with a single directive from her new coaches.

Malcolm: The only goal from the coaches was for me to keep up and I was willing to, you know, I was like, okay, like I'm going to keep up .

Carver: We need to pause here for a moment, because in order to understand over training, we need to understand how training works, period. And why being told to just keep up was really, really poor advice.

Imagine your fitness is a small foam buoy floating in the water. That waterline, that's your base level of fitness. To improve, you have to put stress on your body, whether that's lifting weights, running or cycling. You can imagine any heart activity, any fatigue as a force polling that buoy underwater. Then you rest; let go of the buoy and it shoots back up to the original. What's more, if you get adequate rest, your fitness buoy pops up above the water, at least for a while. That's called compensation, meaning your body adapts to handle a higher level of stress. And if you apply a new load right before that buoy begins to descend again, the buoy will rise even higher after the next rest cycle. Do this over and over and your fitness builds. But here's the catch. If you don't allow your body enough rest and you apply more stress on your body, it's like grabbing that buoy before it's reached the surface and pulling it down deeper than before. Now you need even more rest just to return to your base fitness, let alone reach compensation. Repeat this enough times, pull your buoy deeper and deeper and you'll hit the bottom of the ocean.

So training is a bit of a Goldilocks problem. Train just hard enough and rest just long enough and you'll get better, more fit; train too hard or rest too little and the fatigue pulls you farther and farther underwater, leading to underperformance, illness, and injury, which is why it's absolutely essential for any high volume athlete to be on an individualized training plan. What might propel one athlete upwards will just drag another down.

Malcolm: I was training with the men's team and I remember being like, Hey Loew, what do you have today? And he's like, Oh, I have X number of eight minute intervals. And I was like, Oh, me too. And like I'm 20 and Loew’s 30 and is on the men's national team and I'm doing the exact same workload as these guys. And that makes no sense. Like as a coach, that makes zero sense to have like this cookie cutter program that somehow is supposed to be enough for the high-performing men on the team, and also like your younger junior female athletes. And so I was slipping through the cracks kind of during that whole thing.

Carver: It's important to note here that there's a certain type of athlete more prone to over-training than others, the kind that when told to do eight interval repeats, do ten. And Corrine, she was that type of athlete.

Malcolm: So I'd say that one of my biggest strengths as an athlete is I have no understanding of my own limitations. I'm pretty stubborn and I'm very competitive. But without that being reigned in by someone, it's really easy to have all those strengths be your biggest downfall.

Carver: Rather than back off from workouts she could feel were too intense, she dug in.

Malcolm: Like I wasn't going to cut a workout, and I wasn't going to do less, and I wasn't going to question why I was doing what I was doing, because those were all like threats to my pipeline.

Carver: But we need to be careful here because while Kerryn may have been over-training at this point, she was still a far cry from Overtraining Syndrome. OTS exists on the far end of a continuum of stress on the body, because in addition to the normal stair-step improvement we talked about earlier, there's another idea called ‘functional overreach,’ which means an athlete intentionally overcooks it for a training block.

Hutchinson: By the end of that sort of block --  by the end of, let's say a week long training camp, you don't feel like 1 million bucks. Your legs are heavy and there's a good chance that your times in workouts or your times --whether if you're running or cycling or whatever the case may be, that your pace is lower, you're working just as hard, but you've actually gotten slower, which seems counterproductive. But if you've judged it right, then you ease up for a few days and you're going to find that then you make the big gain. So that's called functional overreaching.

Carver: Hit this balance correctly and your fitness buoy launches out of the water in what's called super compensation, giving you an extra boost to your fitness. But push a bit too hard or fail to take enough rest, and you've entered nonfunctional overreach.

Hutchinson:Three days later, your legs are still dead and a week later you're not faster. You're just barely getting back to where you were two weeks before and you're not better off than you were. You've essentially wasted that training block because you pushed yourself too deep into the hole. And so that's nonfunctional overreaching.

Carver: So even though Corrine was definitely being pushed too hard in training, the fact that she was able to get just enough adequate rest did mean that, for the first winter, she continued to improve, staying just barely on the functional side of overreaching.

Malcolm: I made an IBU Cup team, which is kinda like the minor leagues of the world cup for biathlon. I was showing a lot of promise and had a pretty good year, like raced well at Senior Nationals at the end of the year. Was by all means like keeping up.

Carver: But athletes should only attempt this kind of functional overreach a few times a year, right as they're trying to hit peak fitness for their most important races. Corrine in contrast was putting herself there over and over again, and her body could only keep up for so long, and she knew it.

Malcolm: But I did realize at that point too that I needed to do something a little different. Like I could tell that I wasn't super -- I wasn't finding a lot of satisfaction in like this keeping up notion.

Carver: There's more to this than just dissatisfaction. If there's anything we've learned during the Sweat Science series is that the mind is essential to fitness. And if there's anything researchers have learned about OTS, it's that consistent mental negativity is the proverbial canary in the coal mine.

Shawna Helson: My name is Shawna Helson. My professional title is Associate Professor at the Australian Catholic University.

Carver: Professor Helson is one of the leading experts on recovery science. And she got to be that way by first studying over training and cyclists.

Helson: Participants are -- obviously ethically we can't push people to OTS. So we did a series of studies with cyclists around really high intensified training and we looked at lots of different hormonal measures, heart rate, subjective measures, sleep, lots of different things, immune function.

Carver: She was trying to see if she could pinpoint a biological marker that would indicate overtraining. She did find a consistent indicator, but not in the body, in the mind.

Helson: Sort of ironic that we spent tens of thousands of pounds, I was in the UK at the time, on all these interesting measures. We did stable isotope infusion to look at carbohydrate metabolism. We spent some money, and interestingly enough, the best predictor was what they put down on pen and paper in terms of how they felt.

Carver: That's great. So, it was more about like on the chart of sad face to smiley face versus what biological markers you could pinpoint.

Helson: Yes, exactly.

Carver: This correlation was so strong that it became one of the three co-occurring indicators that would point toward over-training. A decrease in performance combined with consistently negative moods that would last for several months.

Helson: So it's a retrospective kind of -- you're still really suffering at four or five months timeframe. Okay. We think you've probably got over overtraining syndrome

Carver: By the end of her first season at the senior level, it's safe to say that Corrine was reaching the early stages of Overtraining Syndrome. Physically she was performing well, but her mind simply couldn't kick into gear even though she got renamed to the senior team and was posed to race at the World Cup level. Living and breathing training was beginning to crush her spirit. Something had to change.

Malcolm: I realized that summer, the summer of 2012, that I need a little something different. So I move out of the Olympic Training Center into a one room house hut shack thing, like up the street from the Olympic Training Center.

Carver: Perhaps she thought the problem wasn't how much she was training, but that she didn't have anything outside of training to give her a sense of balance. And this is a common issue with OTS, because it can manifest in so many subtle ways. Athletes often search to place the issue in something concrete. Corrine placed the blame for her mental fatigue on how all consuming life at the Olympic center was. Moving out was an attempt to get some separation from her athletic identity, but it didn't help. Corrine’s general mental fatigue began to spiral into full blown depression. The kind that made sleep incredibly difficult, but getting out of bed feel impossible

Malcolm: like this is only a year end of being on the senior national team and there were points that summer where like getting out of bed was a victory.

Carver: It should go without saying that getting adequate sleep is essential to recovery and that poor sleep is correlated with OTS. Corrine's workouts began to feel harder and even the easy days were a struggle. It's a sign of fatigue that Dr. Helson calls uncoupling.

Helson: For example, you might be able to sit fairly comfortably at a certain pace for a certain duration,  if you're a runner. You're naturally normally able to do this, but all of a sudden that starts to feel harder. So your perception of effort kind of uncouples from your physiology, and all of a sudden you either can't do what you previously did or you're doing what you previously did, but gosh, it feels hard.

Carver: And for Corrine, gosh, everything felt hard.

Malcolm: My easy heart rate was way too high. Like if I went for an easy run it would skyrocket. But then when I would try to do intervals, my heart rate would be low. Like it wouldn't be resting levels, but it wouldn't be at my threshold heart rate or at my VO2 max heart rate, it would be much low. It'd be blunted. It'd be much lower than that. I remember, I didn't want to tell my coaches that I was struggling. I felt like it was like a constant, like every day was a test and I like needed to pass the test every day.

Carver: And she would be damned if she was going to show weakness or fail or even admit to herself that anything was wrong. Besides her own motivation.

Malcolm: You're like, well obviously I'm just not training hard enough. Like that's why I don't feel, it's not cause I'm tired. It's not because I haven't rested. It's not cause I'm not fresh. It's because I'm out of shape. I was like, okay, clearly I can't cut corners. They say 20 hours, I'm training 20 hours this week. Um, and that like, that has repercussions.

Hutchinson: And so often the cycle is self reinforcing that you're maybe on the verge of over-training or maybe you're just in functional overreaching, but you conclude that this means you're getting unfit and rather than that you're overtired and so you push harder and that's where I think a lot of people who end up digging the deepest holes for themselves often do it because they sense something is wrong and their response is to work harder rather than recover more.

Frick-Wright: We'll be right back.


Carver: What's remarkable here is that really none of this should have happened. Even though elite level athletes are training under extreme loads, it's rarely the professional that is bouncing from doctor to doctor trying to figure out what's wrong with them.

Dr. Robert Amrine, a sports physician in Missoula, Montana who specializes in treating overtrained athletes, gives the example of one of the Olympians he works with.

Robert Amrine: A high level, Olympic level athlete, and he would always entertain me because I'd asked him what he was up to and he was like, Oh, I'm going to take a nap. And I was like, well geez, like it's four o'clock in the afternoon. He's like, yeah, I usually nap between three to five o'clock. Then I get up and I socialize for about an hour and then I go back to bed and get like 13 hours of sleep and then wake up, and he probably trained 35 to 40 hours a week through cross training, strength training, etc. But at the end of the day, he also slept 14, 15 hours a day. He never really had problems with the over-training type of concept cause he had adequate time to rest. He had really nothing else in his life except his sport.

Carver: With this in mind, it's easy to see why overtraining syndrome began disproportionately plaguing the ultra running community, which especially 10 years ago had little professional infrastructure and was largely made up of amateur athletes trying to juggle everyday life with training for a hundred mile races.

Amrine: On the flip side, I got a phone call for a consultation once from a man who'd he'd seen every doctor that he could possibly think of seeing and he was desperate for help. And just listening to a story, I asked him, well, what's your goals? What's going on in your life? And he said, well, I'd really like to run Western States Hundred, this is a big goal for me. And at the end of the day I said, well, how long are you training per week? What’s your running scheduling? He’d say, well, I'm averaging between a hundred and 150 miles a week. I say, well, what else is going on in your life? And he said, well, I've got two kids under the age of five and I just got promoted at work and I'm an executive for a high level corporation. And the final answer I asked him is like, well how much do you sleep? And he said two hours a night. And that's it. It's like I think we found the problem is

Carver: What Dr. Amrine illustrates here is that it's rarely the training itself that tips an athlete over the line from nonfunctional overreach into full blown OTS. Rather it's the accumulation of stresses outside of training that does it. An athlete performing at the very edge of their ability needs everything else to be perfect: getting enough sleep, eating enough food and staying removed from the everyday pressures of life. Put another way, when you're walking a tightrope, every gust of wind risks knocking you down. And Corrine, she was facing a storm.

First there was the boyfriend.

Malcolm: And during this I also like I was dating a teammate and then we broke up and we weren't very good about breaking up.

Carver: Second, moving out of the training center not only increased her sense of isolation, but because she now had to pay her own living expenses, money was suddenly an issue. She became constantly anxious about her finances. The anxiety itself was another heap of stress, but even worse the way she dealt with it: she sacrificed her nutrition.

Malcolm: I was living a poor vegetarian lifestyle, I would say at the time, like not a very smart vegetarian. I was probably eating a diet that was like too low in carbohydrates and too high in fiber and not enough fat and not enough protein.

Carver: Despite needing to take in hundreds more calories than she was eating, Corrine didn't feel like she was starving herself. This has to do with a quirk of biology that begins to show itself as an athlete progresses towards over-training.

Hutchinson: One of the things about exercise is it actually kind of sharpens the accuracy of your appetite signals. People who are getting exercise are far more likely to eat a little bit, just unconsciously eat a little bit more, a little bit less depending on whether they've exercised little bit more, a little bit less. But at a certain point when you're really, really training hard, in other words, when you're on the verge of overtraining, that breaks down and the act of going and running for three hours, you burn a lot of calories, you come back, you just don't feel like eating. And so you've got this double whammy where your calorie burning is through the roof, but your desire to eat is lower and you've, and yet you've got to try and shovel in this sort of rather extreme amount of food.

Carver: It should be no surprise to learn that chronic calorie deprivation is linked with OTS. In fact, a recent study by Belgian researchers at KU Leuven that pushed a group of cyclists into nonfunctional overreach, made a startling discovery.

Hutchinson: Basically they took 18 cyclists and they put them through a sort of simulated Tour de France. So three weeks of unwisely heavy training.

Carver: Their goal was to see how the effect of ingesting synthetic ketones, a type of fuel your body only naturally makes when it is near starvation, aided in recovery. Half of the cyclists in the study received three ketone drinks a day, and the other half took a placebo drink. After three weeks, they ran some tests.

Hutchinson: The cyclists who had the ketones were able to produce about 15% more or to sustain about 15% higher training load in that third week.

Carver: In other words, rather than becoming overreached and losing steam, these athletes were actually improving. And while it is unclear exactly why taking ketones had this effect, one thing that immediately jumped out of the study had to do with how much food the two groups ate.

Hutchinson: By the third week, the people who are just doing the normal, they're no longer managing to replace all the calories they're burning; they're training super hard and they're eating about 800 calories per day less than they're burning. And this, not surprisingly, you do that for a week, you're going to be in trouble.  The ketone group, on the other hand, their caloric intake kept increasing, so their training got harder in the third week and they ate more. They were actually eating 4,200 calories a day in the final week, whereas the non-ketone group was eating 3,500 calories per day.

Carver: Somehow taking ketones, kept the body from suppressing their appetite despite the intense training, and kept their hunger levels in line with their true caloric needs.

Hutchinson: Now no one told them, eat this or eat that. This is just what they chose to do. So there's a couple of big questions. One is, why does taking ketones three times a day lead people to eat more? And the second is, is the positive effect we see, is the apparent sort of defense against overreaching, is that just because they ate more? And if so, maybe we can get some of the same effects just by being more diligent about not dropping into that sort of zone where you're so fried and cooked that you just can't manage to, or you don't choose or don't want, to eat as much as you actually need to.

Malcolm: But Corrine of course wasn't taking ketones and she was training as hard as an elite male skier while subsisting on a slim diet of vegetables and green. Her caloric deficits snowballing over months of training. Add this to the depression, sleep deprivation, the pressure to perform, financial anxiety, social isolation, and relationship stress. And the only pipeline Kerryn was on now was the one straight to overtraining syndrome.

Malcolm: Although training might not have been too much, even if it was close to too much, adding any of those additional stressors to that create like the perfect storm to like spiral from overreaching, which is like an action, to the state of overtraining syndrome, which is like a final destination. You don't overtrain, you end up there.

Carver: Corrine continued to train through the winter, but her problems continued to mount. She kept getting respiratory infections, developed a persistent anemia, and couldn't perform at her normal level. She failed to make the national team. She knew her Olympic dreams were in jeopardy and unless she did something drastic, she was done.

Malcolm: I was like, I don't think I'm going to be in this sport next year. Like I was starting to recognize that like, not only was I emotionally unhappy, but I was like physically realizing that I was like not in a good spot.

Carver: So she asked for permission to return to Montana to reset and train from there.

Malcolm: I raced that winter, and being on my own schedule and training a little less, I started to actually race a little bit better, but that was short-lived, which is like very, very common in overtraining syndrome is that you have these periods where you can race really well or perform really well on workouts, and then you have these like major slumps.

Carver: Her few good days became fewer and the slumps got worse, longer, more severe.

Malcolm: I would tell people, like I feel like a six cylinder engine who can only use four cylinders, like at the highest level. Like that's all I can get to is four cylinders and there's this extra depth that I know I have, or I have had, that isn't there or I cannot access. And that's what that whole sensation was. There's no energy, there's no spunk. It's deep and it's not like the surface level of fatigue. Like, oh, you did a long run yesterday and now you're tired today. It's like, it's deep. It's like it's deep in your muscles and it's deep in your body and you get a good emotional cry in sometimes, like you go for a run and I need to start crying for no reason. You'd have a little sit down, like you'd be out in the woods running and you need to take a sit down to cry for a little while.

Carver: But despite everything telling her to stop, slow down and rest, she'd wipe her tears and continue to train. In August, Corrine entered the first round of Olympic trials and did well enough there to make it to the next round in October. If she could just hold it together, she still had a shot at becoming an Olympian, but by September she knew she was done.

Malcolm: I basically told the national team that I would not be continuing with Olympic trials and that I was sick, is what I called it. I said I was sick. And that for my own health, I would be taking time away from the sport. And that’s what I did, like I like quit cold Turkey in the middle of Olympic trials.

Carver: Corrine had devoted her entire young adult life realizing her Olympic dream, but she never competed in the biathlon again.

Malcolm: It's not like going to medical school where at the end of it, like you're a doctor; like as long as you don't do something really weird, you're a doctor. You put four years in, you come out with like this thing. You put four years into making an Olympic team, you put a lifetime into making an Olympic team, and if you didn't make the Olympic team, you're not an Olympian. And so like you have that weird gap in your resume where you're like, what were you doing for eight years? And you're like, Oh wow. I was skiing in a circle with a rifle.

Carver: Researchers don't fully know what happens within the body when it reaches OTS, or why it's so hard to come back from. There's a number of competing theories having to do with parasympathetic predominance, oxidative stress, dysregulation of the hypothalamus, and something called catecholamine excretion. But root causes in fancy names aside, it does appear that something becomes permanently altered in your physiology. Dr Amrine likens this to what happens to the body during famine.

Amrine: The theory is that you're basically going into a safety mode of sorts where your body thinks it's starving to death and you have to figure out a way out of that predicament. I mean our bodies are so good at adapting, and trying to survive. Through all the famines, every aspect of our life, how we're programmed is to survive. And so it's now trying to figure out how do I survive through this time frame of induced starvation of sorts.

Carver: Dr. Helson suggests that there might be some form of psychophysical trauma that prevents an athlete from pushing themselves so hard.

Helson: Your body was in a very bad place and it says, I don't want to ever go back there again. And it will almost make the individuals feel tired and make it difficult to do what they would normally do just as protection.

Carver: Alex Hutchinson likens it to putting your body in a constant state of high alert.

Hutchinson: Eventually what seems to happen -- you're putting your body into a state of alarm into ramping up the fight or flight system, and then it's adapting to be able to handle that sort of stress. But at a certain point, the alarm just stays on. It's like, well, we're getting pummeled so frequently and so severely, we're just going to leave the fire alarm on all the time. We're going to be in fight or flight mode permanently and your body just can't sustain that. So that's the kind of hand-waving explanation. I wouldn't necessarily say it's quote unquote science, but that seems to be part of what's happening is you're pulling the fire alarm so frequently that it just never goes off.

Carver: There's currently no cure for OTS aside from absolute rest, with no guarantee that your body will ever return to its former performance levels. And one of the major difficulties for athletes and doctors remains how to catch overtraining before it reaches OTS. Elite athletes have to constantly push themselves right up to the edge of the cliff, extracting every ounce of fitness from their body without overdoing it. But there's simply no objective measure to point at that says you're at risk of falling off.

Except maybe that's no longer true.

Hutchinson: Now to go on a little bit, I'll just say that they measured a bunch of things and one of the things they measured was appetite hormones.

Carver: The recent ketones study Alex described earlier may have accidentally found a signal to warn an athlete that they are on the verge of over training.

Hutchinsons: There's something called growth differentiation factor 15, GDF 15. It's a stress induced hormone that basically causes you to decrease food intake cause you're just stressed out and it's levels were higher in the non-ketone group, and they started to climb before there was any signs of overtraining. One of the things that the researchers suggest in a speculative way is, wow, maybe this is the smoking gun that indicates overtraining is on the way. There could be correlation, it could be causation, it could be coincidence, it could be statistical randomness. All options are on the table at this point. What all they have right now is this sort of intriguing pattern that suggests maybe GDF 15 is one of the keys at the heart of this mystery.

Carver: To be clear, the study wasn't specifically looking at this hormone and was exploring nonfunctional overreach, not overtraining syndrome, but if athletes can take a blood test that shows their GDF 15 levels are raised, that could be the kind of specific objective test that convinces them that they need to back off before it's too late.

Hutchinsons: We all know, okay, your legs are dead, your performances are declining, you need to back off, you need to manage the stresses in your life, blah, blah, blah, blah, blah. But it's very hard to do that when all the medical tests keep coming back saying, Oh, you're fine, there's no signs of any problem, other than your performance is going down, but we don't know why. And if we can say, well, here's this marker, here's this blood marker that suggests you're on the verge of over-training. Maybe that will give the athletes what they need.

Carver: After walking away from the Olympic trials, Corrine re-enrolled in college. If she wasn't an Olympian, she decided she was a student; she quit training completely and would only join friends on runs or skis if the pace was conversationally easy. And that wasn't just for a psychological break.

Malcolm: It felt terrible. Like I think it took 18 months before I felt fresh again. I like distinctly remember running with my then boyfriend, now fiance, just running in Bozeman in town and like being like, Holy shit, I feel fresh. This is what freshness feels like. Like I have not felt this in years.

Carver: Eventually, Corrine got back into sports and today is not only a coach, but believe it or not, a professional ultra runner.

Malcolm:And this spring for the first time ever, I was like, I think I'm ready to like be a quote unquote serious athlete, whatever that means. But I'm willing to finally focus again. And I think that's kind of one of those final pieces of this whole recovery process is that I've kind of mentally recovered from that kind of traumatic experience and changed my whole outlook on sports.

Carver: But even so, OTS has stayed with her.

Malcolm: Like, I'm still not the athlete I was and that probably sounds weird cause I'm like a successful ultra runner. But there's a reason why I don't run really competitive 50 Ks, because I don't have the upper part of my engine. Like I've never gotten that back. And so like a hundred mile race I can suffer through because that's something that I have got, like I have those capabilities, there's no timeline of recovery with OTS. You may never get better. And that's not great.

Carver: If there's a silver lining to overtraining syndrome, perhaps it's this: it forces you to reevaluate your goals to decide what's truly important. If you've reached OTS, you've had to have dedicated an incredible amount of time and energy to your sport. OTS gives you the chance to step back and ask, what did that dedication actually mean?

Malcolm: As I am wanting to spiral, I was like, people are going to be disappointed in me, my parents are going to be disappointed in me, my coaches, my friends. Like I had all this false external pressure that was really all internal. Then as soon as I pulled the plug, I had the most intense sense of relief.

It didn't make me a quitter and it didn't make me a less valuable human being and it wasn't tied to my self worth. Those are lessons that I've been able to take from that to like coaching kids who are stressed before races and you're like, are your parents still gonna love you? Are your sisters still gonna love you? Am I still gonna love you? And you're like, yeah, okay. Like it doesn't matter how the race goes or how the season goes because like your self worth is not tied to it and it took stepping away to realize that my self worth as a human had nothing to do with me as an athlete.



Frick-Wright: This episode was written and produced and the music composed by Robbie Carver. It was edited by me, Peter Frick-Wright. It was based on the article “Running on Empty” by Meaghen Brown. Michael Roberts is our editorial overlord. This episode was brought to you by Bob's Red Mill, helping athletes attain proper nutrition by providing them proper ingredients; more at bobsredmill.com.

The Outside Podcast is a production of Outside Magazine and PRX. We'll be back next week.

Follow the Outside Podcast

Outside’s longstanding literary storytelling tradition comes to life in audio with features that will both entertain and inform listeners. We launched in March 2016 with our first series, Science of Survival, and have since expanded our show to offer a range of story formats, including reports from our correspondents in the field and interviews with the biggest figures in sports, adventure, and the outdoors.