Let’s be frank: Anyone who loves extreme endurance sports is probably a type A overachiever. But when we move to ultra-endurance events, you can delete the “probably.” People who relish the challenge of running 100 miles are out there on the far end of the bell curve. The reality is that it’s only a short step from “training” to satisfying an unhealthy compulsion. We feel that there needs to be an open and honest discussion in our community about overtraining syndrome (OTS)—the elephant in the ultrarunning room—and the damage it imposes on individuals and ultimately on the sport as a whole.

In our combined decades of coaching and athletic experience, we have seen the unhealthy effects of compulsion wreak havoc on the minds and bodies of many endurance athletes. Overtraining is the scourge of endurance sports because of this basic law of endurance: “The one who trains the most wins.” This admitted oversimplification generally holds true—until it doesn’t. The landscape of endurance sports is littered with the broken bodies and crushed dreams of those who push too far for too long.


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Defining Overtraining Syndrome

Overtraining syndrome is the result of continual overreaching. The two are often confused with one another.

Overreaching is a state of temporary fatigue due to an excessive training load. When followed by a recovery period of a few days, overreaching will always result in supercompensation to the training. This leads to improved performance in the short term.

Overtraining is state of longer term fatigue that, when followed with a reasonable recovery period, does not lead to improved performance. This indicates a maladaptation to the training.

For this article, we reached out to many endurance athletes to learn about their experiences with overtraining.

Professional ultrarunner Clare Gallagher won the 2016 Leadville 100 and took second at the highly competitive North Face Endurance Challenge in 2017. The same year she won North Face, she struggled with a bout of overtraining. “[I spent] too much time exercising all winter, including racing Black Canyon 100k in February, when I knew my body needed a break from the previous year,” she explained to us. “Skiing at altitude while continuing a normal running training regime was way too much exercise. My stoke totally backfired on me. I was a sluggish, injured, depressed mess.”

Kilian Jornet experienced something similar in 2007. “In 2007 I overtrained. I did a big winter with 30 skimo races and then I started running right away. The first indication was that I was not recovering at all. I was super tired. Since I felt bad for a few weeks I did a blood test to see if I had an iron deficiency. Sure enough, I had super low iron levels. So I rested completely for two full weeks. After that I started training again very, very easily. I think I caught it early so I did not need to take much time off, which was good.”

Image by Steve House.

Kilian Jornet points out the planned second peak of the day after deciding one summit was enough for this day.

Recognizing Overtraining Syndrome: A Fine Balance

Overtraining syndrome is not fatigue like you know it. It is a complex medical condition that is very difficult to diagnose and even harder to treat. It often goes unrecognized until the wheels have come off. The more-is-better ethos of endurance athletes and the necessity of very high work volumes accompanied by near-constant fatigue often mask the developing OTS symptoms, confusing both athlete and coach.

In its simplest form, OTS manifests itself as an injury. These are easy to notice and hard to ignore. You are broken and need to heal. A more insidious and demoralizing potential effect of overdoing structured endurance training is the failure of the body to adapt to training stimuli. When in an overtrained state, you become less fit even though you are training at the same—or maybe even a higher—level as before.

When asked what red flags she noticed that signified she may have been overtraining, Clare Gallagher mentioned both an “extremely high heart rate on easy runs” and persistent leg fatigue. “My legs felt so sore after just easy running,” she remarked. “Lifting my legs was a burden and my heart wouldn’t stop racing, even on slow, flat runs. I felt like shit.”

Athletes who try to extract their maximum potential are in a delicate balancing act, precariously close to the physiological edge between supreme fitness and utter physical collapse. The higher the level of the athlete, the narrower the edge and the harder it is to balance there. An increase in fitness comes only as a result of increasing the training stress on the body. The often elusive goal of every elite athlete is to find the proper balance between training and recovery. Not enough training stress and you will not achieve your potential for the training cycle, perhaps by a few percentage points. Too much stress and you risk falling off the overtraining cliff. Doing so means you will not reach your potential by a huge margin.

Life Stress and Training Stress

Balancing training loads with the additional stressors of life—such as family, work, or school obligations—complicates the job of maintaining this critical balance. Ignore these normal life stresses at your peril.

Justin Angle, a Patagonia trail running ambassador and the Plain 100 course record holder, hasn’t always respected this delicate equation. “Think about the life-stress variable,” he advises. “That’s been the key in my life. I’ve not done a good job of looking at my athletic life holistically, failing to consider the effects of work, family, parenting stresses.”

Endurance athletes find themselves at the highest risk for overtraining due to the high energy demands of their training (more than 6,000 kcal/day at times) and the concurrent stressors involved in their daily regimen. Unfortunately, most athletes don’t recognize overtraining. In many cases, it takes so long to acknowledge the overtraining that by the time it is properly diagnosed, it is usually too late for anything but the most draconian measures.

Overtraining syndrome is responsible for more failed athletic goals and shortened athletic careers than any other factor besides injury. Some athletes struggle with it over several years of stagnation before throwing in the towel.

Overtrained vs. Undertrained

It is far better to be undertrained than to be even a little overtrained. This is an important training axiom to keep in mind. If you are undertrained and well rested, you can always draw a bit deeper from the willpower well during competition. However, if you are overtrained and tired, no amount of willpower can conjure strength and endurance from an empty well.

Krissy Moehl, winner of many of the biggest 100-milers in the world, including the Hardrock 100 in 2007 and the Ultra-Trail du Mont Blanc (UTMB) in 2009, shared a similar experience from a race she went into overtrained: “[M]y own well was dry, and when I looked to find a little more in myself, there was nothing.”

In contrast, Moehl took another approach leading up to Gaoligong by UTMB in China, which she won in March 2018. “Training for the Gaoligong 100, I pulled back, way back,” she shared. “Rather than running the 75-, 85-, and 95-mile weeks I [had]planned, I ran about 25 to 35 miles a week and focused on twice-a-week strength classes, two-to-three-times-a-week yoga, cooking, and resting on the couch with my pup. For the month prior to leaving for the race, I focused on minimizing as much stress as possible, good or bad. When it got hard during Gaoligong, like any 100-miler inevitably does, I had the reserves to deal, to switch my mindset and have something in the well to pull from to finish the race.”

Image by Fred Marmsater

Krissy Moehl after finishing and setting a new FKT on the Wonderland Trail around Mount Rainier in 2013.

Motivation vs. Compulsion

Everyone involved in high-level athletics is driven to excel. Willpower, perseverance, drive—whatever you want to call it, the fire that burns hot inside your soul is without a doubt the most important attribute you have as an endurance athlete. It can also be your worst enemy when it clouds your judgment and becomes a merciless taskmaster. Overtraining syndrome is not merely getting stiff and sore from a hard workout or needing a couple extra days to recover from a particularly demanding race. That sort of short-term fatigue is overreaching and is a normal part of the training cycle, as described above. When chronic overreaching develops into overtraining, you have crossed a physiological bridge that can be difficult to recross unless you take drastic action.

As Krissy Moehl observes, “FOMO can be a final tipping point into OTS—feeling strong from training and not realizing that ‘just one more run’ could take you over the brink.” 

Early Signs of Overtraining Syndrome

The first and most common signs of the early stages of overtraining syndrome are repeated shortcomings in performance accompanied by a feeling of flatness or low energy.

When Anton Krupicka, who has won the Leadville 100 as well as the Lavaredo Ultra Trail, began to notice an “inability to hit times for intervals or uphill tempos that would normally come easily to me” and a “general lack of motivation,” he couldn’t pinpoint the cause. “I can never tell if my motivation wanes because I always feel shitty running or I feel shitty running because my motivation is low.”

The coach’s or athlete’s typical assumption is that this performance decrease is caused by a lack of fitness. After all, you were feeling so good just a couple of days before; it can’t possibly be overtraining.

Overtraining is not your garden-variety fatigue that all endurance athletes learn to live with. When you step over this threshold you are entering a medical condition that is poorly understood, multifaceted, and very difficult to diagnose except by those who have experience with it. Your family doctor is likely to call you a hypochondriac if you present the typical symptoms of overtraining. Even a moderately overtrained endurance athlete is still the picture of health and energy compared to the typical patient. Only in the latest stages of OTS will you present recognizable illness symptoms that are treatable with medical care.

OTS represents a breakdown of your body’s natural adaptation processes. The endocrine and nervous systems no longer behave as you have come to expect them to. What was once a light training load, because your body could adapt to it, even in a short-term fatigue state, is now an intolerable and destructive stress. You have to completely recalibrate your concepts of “hard” and “easy.” Most of us are unprepared for this dramatic shift and unwilling to accept that we can go so quickly from feeling like an athlete to feeling like an invalid.

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The Common Response

The typical response when performance drops, especially by the self-coached, is to immediately add more training. The assumption is that your training program lacks some key ingredient, and if you just add more of this or that, your lost fitness will return. After you increase your training with no improvement—likely notching a further decrease in performance instead—you continue to seek solutions that involve more training. Thus begins a dangerous downward spiral that can ultimately lead to more than just physical problems. You have invested a huge amount of time, energy, and resources in your physical preparation. In many ways your sport and your performance in it may define your persona. When you keep coming up short in training and races and suffer with constant deep fatigue, it will have dramatic and costly effects on your motivation and confidence.

Overtraining is more easily recognizable if you are training on measured courses or using measured paces, because you can see your times drop off. It’s much harder to recognize in mountain sports where the track is different every day. This is one reason that we advise establishing benchmark workouts you can do to check for progress or regression in your program.

Overtraining Syndrome Symptoms

The earliest effects of overtraining impact the sympathetic nervous system. Overtraining syndrome starts with the immediate effect of an elevated resting heart rate and a higher heart rate for submaximal levels of exertion. You lack your normal pep and vigor and feel flat in training. The levels of the stress hormone cortisol begin to stay elevated between training sessions (which takes a trip to the doctor to determine). You’ll probably notice some difficulty sleeping through the night.

Darcy Piceu, multiple winner of the Hardrock 100 and current women’s John Muir Trail record holder, shared some of her symptoms: “Increased resting heart rate, night sweats, anxiety.”

Similarly, Krissy Moehl has experienced “full-body sweats at night, the necessity of midnight meals, huge fatigue midday, then not being able to go to bed at night due to cortisol levels.”

If you do nothing to mitigate the early overtraining, it can progress to a much more debilitating type involving the parasympathetic nervous system. When this occurs, there are more negative hormonal effects and a lowering of the heart rate for all effort levels compared to normal rates. It will feel like you can’t raise your heart rate even during hard efforts. Your resting heart rate typically also drops when you reach this stage.

Among the symptoms Justin Angle noticed were “frequent soft-tissue problems that wouldn’t heal. Poor sleep. Insatiable hunger. Bloating. Anxiety.”

athletic recovery with physical therapy

Watch for one or a number of these unpleasant symptoms:

  • Persistent, deep fatigue such a shortness of breath when climbing stairs
  • Prolonged elevated cortisol levels. This requires blood tests to establish a prefatigue baseline.
  • Lowered testosterone levels (requires a blood test). As above, this requires establishing a baseline with blood tests when rested and healthy.
  • Decreased heart rate variability (requires a special heart rate monitor or EKG)
  • Irritability
  • Depression
  • Weight loss
  • Amenorrhea (absence of menstruation)
  • Insomnia
  • Lowered libido
  • Loss of enthusiasm and motivation

This profound state of deep fatigue necessitates, at the minimum, several weeks of complete rest. Only then can you gradually reintroduce easy exercise. Sounds grim, right? It is a condition to be avoided at all costs. The cost of overtraining and underrecovering is so much worse than undertraining; it is far better to err on the conservative side.

Overuse Injury as an Indicator of Overtraining

If a muscle is exposed to a new training load on a routine and consistent basis before adequate recovery and adaptation from the previous training session has occurred, at the very least no fitness gains will be seen. It is more likely, however, that the cumulative effect of this premature stress will cause small injuries that will weaken the muscle or tendon. The muscle/brain connection will then self-inhibit the ability to contract the muscle in an attempt to protect that muscle from further damage. A dedicated athlete can easily overcome this pain and suffering and manage to maintain the overuse. But soon a minor tear will turn into a major inflammatory cycle leading to overt injury and scarring. Chronic tendinitis or worse—full tendon or muscle rupture—can occur.


“I experienced a femoral stress fracture scare and started running after taking two weeks off at the end of March 2017, and my heart rate was through the roof on easy runs,” revealed Clare Gallagher. “Had I not had that stress fracture scare, I probably would’ve dug a hole way deeper than what I experienced. I was able to feel normal within a month.“

While these injuries are not necessarily an indication of overtraining as discussed above, they do point out that the adaptation you are seeking through training is not occurring. This lack of adaptation can be a good indicator that you are on a collision course with overtraining if you do not initiate some remedial steps immediately.

Take these warning signs for what they are: your body’s red-flag attempts at getting your attention that things are amiss. Rather than get caught up in numbers and times, pay attention to the bigger picture of your body’s responses to the training.

woman foam rolling
Image by Fred marmsater

Krissy Moehl in Tahoe, California.

Avoiding Overtraining Syndrome

Darcy Piceu: “Listen to your body. If you’re tired, rest. Get more massage and do things that relax you. Don’t run so much. I never log 100-mile weeks, even when training for a 100.”

Clare Gallagher: “Monitor your heart rate on easy runs. If you feel your heart is racing on a classic recovery run that should feel like walking, that may be a harbinger for OTS.”

Justin Angle: “Be honest with yourself. Don’t be afraid to take a day or two off. Really learn how to listen to your body.”

Krissy Moehl: “Stress is a huge factor in leading to OTS. Your training is a stress on the body. Your life is potentially a stress on your mind and body. You may be able to pull off a perfect training plan one summer, but then the next summer you end up faltering. Look at the external factors, things that are different year to year. Give credit to all that you are managing and know that something may have to give.”

The simplest way to avoid the debilitating effects of overtraining syndrome is to monitor your levels of fatigue and take action before the wheels come off. For the majority of us who do not have a medical staff to oversee our day-to-day hormone levels, we propose a series of practical steps for staying well back from the edge of the overtraining cliff.

Pay attention!

Don’t treat your body like an appliance, expecting perfect toast every time and getting pissed when the toaster doesn’t work. We are not machines. The process of adapting to training is very complex with multiple overlapping, interdependent physiological systems involved. Your body gives you feedback on how prepared it is for the next training session. Many times this feedback is very subtle, and you need to be sensitive in order to understand it. If your training plan is your taskmaster or you are compulsive, you may not hear the message over all the noise.

Train for yourself.

Do not be influenced by others’ impressive training feats. Trying to keep up with faster athletes or trying to break your own or others’ records regularly in training will lead you right over that OTS cliff. Save your races for race day.

Remember that training is not the only stress you have in your life.

Very few athletes have this luxury. For most people, relationship/family and work stresses account for as much stress as training. These nontraining stressors have some of the same effects on you: they increase cortisol levels and keep your sympathetic nervous system revved up. Failure to take these factors into account can easily lead to OTS. In times of elevated life stress, be prepared to reduce your training stress.

Establish a baseline for monitoring your fatigue.

You can use any of several methods to establish this baseline, from the complex and expensive blood tests mentioned above to a very simple stair-climbing test that is easy to do daily. Below we describe two simple tests that can indicate when you should back off—well before the cliff.

Modulate your training load.

Pushing hard is fine, but plan for a recovery period of lighter training loads. You can do this on a daily cycle, where you have a big day or two followed by one or two easy days, or weekly so that you have two to three weeks of increasing loads followed by several days or a week of planned recovery with much lighter loads. Carrying the same training load constantly will at the very least make you stale.

If you feel inordinately tired or unmotivated, take time off.

Missing a few days when you are fit and just a bit tired will have no long-term negative performance implications. Failing to rest when you need to can easily result in missing several weeks—probably when you can least afford to miss them.

Karl Meltzer, who has notched more 100-mile wins than anyone else in the world, has noticeably avoided overtraining throughout an incredibly robust career. He credits a lower mileage diet and deliberate rest when tired: “When I feel tired, I rest, period. I never feel like I MUST do a block of training. … I think I know lots of guys who overtrain. ‘Karl just runs what he feels like running,’ and for some reason, 60 miles per week is plenty to win lots of 100s.”

female skimo athlete fueling up with a recovery drink outdoors
Image by Genis Zapater

Fatigue-Monitoring Tests

Staircase Test

The first and simplest test is to pay attention to how your legs feel after climbing a set of stairs. Preferably these will be stairs you climb every day.

Stage 1: Fresh and ready for a race or hard workout.

You know how your legs feel when you are fit and rested: You bounce up these stairs, maybe skipping steps, maybe running up. At the top your legs still feel light and bouncy.

Stage 2: Normal fatigue but needs minding.

Compare that with how your legs feel during heavy training where you are responding and progressing well. You feel some local muscular fatigue at the top, but this dissipates in a few seconds. Even taking the stairs two at a time is not a big deal. If this fatigue persists for more than two to three days in a row, you need to back way off and give your muscles a chance to catch up to the training load.

Stage 3: The start of overtraining syndrome.

If you don’t listen to your fatigue and back off, you will surely end up here. Your legs feel heavy and dead; even the idea of bounding up two stairs at a time makes you tired. You feel short of breath at the top. These are clear indicators that you need to drastically adjust your training immediately. You have overwhelmed your body’s ability to adapt and need to reduce your training load. That reduction might be two to three days off or a few days of lighter/alternative training. Failure to heed this signal is the most common reason people end up going over the cliff.

Step-up Test

The second test is more complex but can be more predictive. This test applies a slight stress to your sympathetic nervous system. You then measure your body’s response to that stress. The exact procedure is not as critical as doing the same procedure each time. Establish a baseline by doing this test when rested in the early stages of a new training cycle. Record the results every day for a week.

  1. With a heart rate monitor on, step up and down on a step/single stair at a moderate tempo—one you can repeat each time you do the test. The exact time/step rate and step height are not so important; just make them repeatable.

  2. Step up and down for 60–90 seconds.

  3. Note your heart rate at the end of the stepping time.

  4. Immediately sit down on the step, then record your heart rate at 30 seconds and 60 seconds after sitting.


When you are rested, after 60 seconds of stepping you note that your heart rate has risen to 100 beats per minute (bpm), and then 60 seconds after sitting it has dropped to 63 bpm. During heavy training you might see 110 bpm and 70 bpm. When very fatigued, you might see 115 bpm and 85 bpm.

Advice for Dealing with Overtraining Syndrome

The common thread among all those whose input we got and among all the athletes we have known and worked with over the years who have suffered from overtraining syndrome is that you must rest. This sounds so simple and yet it is the hardest thing for most athletes to do. Pulling back is like admitting failure, which is a bitter pill to swallow. But not doing so is the most common reason for people falling farther over that OTS cliff.

Prematurely trying to come back to training—and especially trying to come back where you left off—is a certain path to destruction. When you are overtrained, the time needed to rest and recover will mean you will lose significant fitness. There is no way to avoid that. When you realize you’ve stepped over the line, stop and rest. The sooner you do this, the sooner you can get back to effective training.

Justin Angle: “[I t]ook significant time off. Started eating a lot more. Started putting more emphasis on sleep. Prioritized weight training upon return to exercise.”

Clare Gallagher: “Stop running fast, and possibly stop running period. Taking two weeks off completely could save a year of running in your future. OTS is serious and I feel like ultrarunners older than me have completely fallen off their game due to overtraining. It’s so sad, and frankly, so preventable. A coach really helps with noticing this.”

Krissy Moehl: “Get input from an outside perspective. It might feel like you can manage, but adding training to a busy life plate can put you over the edge. That third-eye perspective from a coach or someone not in your immediate world can give you a ton of light on what you are managing and what is realistic for a sustainable practice.”

This article was originally written by Luke Nelson and Mike Foote. 

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