mental fatigue

Mental Fatigue in Ultramarathon Running

By Jason Koop,
Head Coach of CTS Ultrarunning

We’ve all seen this scene play out. A runner’s crew enters an aid station with enough gear to supply a small platoon. Four duffle bags, three pairs of spare shoes, copious amounts of fluid, nutrition, lubricant and an ice bandanna – all laid out on several yoga mats. Having meticulously memorized the 10-page spreadsheet full of 8-point font instructions, the crew has the upmost confidence this will be a smooth and efficient aid station. Until the runner arrives.

The runner quickly rattles off the series of instructions he has been repeating in his head for the last two hours, none of which were in the phone book passing for aid station instructions: “One bottle should have one scoop of HEED and ¼ scoop of Roctane. Not ½ scoop HEED. The other bottle should have half a NUUN tablet and a gel. Not one of the vanilla gels, the lemon-lime ones. Now, I need you to put the salt pills in the left shoulder pocket. No, not those salt pills, the other ones with the two-times sodium. Now I also need the 40 SPF sunscreen, that’s in the front pocket of the blue duffel. No, not the light blue duffel. The Patagonia one. No not that Patagonia one, the other one.”

And on and on and on. The whole song and dance will take no less than 20 minutes. Once the runner’s pack is exactly to his liking, he will shuffle out of the aid station, promptly forgetting said pack that was just so meticulously packed. Realizing his error, he will return a few minutes later to collect his things, albeit a bit embarrassed and a few minutes in the hole for the effort.

If you think that the aforementioned scene is an error in planning, you’d be right. But what lies beneath the surface of an overly meticulous plan is more problematic for ultrarunners. Mental fatigue caused by many small and usually insignificant decisions (the red gel or the blue gel?) over the course of long periods of time, compounded by physical fatigue, is a constant source of degraded performance in ultrarunning.

Mental fatigue is fatigue

During training, an inordinate amount of time is spent training for the physical fatigue encountered on race day. We run and hike hours per week in an effort to train our physical bodies to be prepared for the task at hand. The physical part is hard. It’s also tangible and easy to grasp, thus we focus on it more in training and in race preparation. For example, many athletes have a pacing plan for their event. That plan is rooted in optimizing the physical exertion necessary for the event. Few athletes, however, incorporate ways to reduce their mental exertion during the event. And, I would make a bet that most athletes’ race day plans actually place MORE stress on them than they would experience in training by incorporating unnecessary choices (the blue Patagonia bag), more options, and needless complication.

Mental fatigue, because it is less tangible, is often neglected. Athletes, coaches and researchers have had a hard time with the concept, were it stems from and how to combat it. The best way experts have come to describe it is, “A psychobiological state caused by prolonged periods of demanding conative activity shown to negatively influence physical performance.” That’s a mouthful.

If you comb through the literature (here is a good start), you will find that in fact, mental fatigue does affect endurance performance in such ways as time to exhaustion and increased rate of perceived exertion. However, mental fatigue does not seem to affect (or at least not much) the physiological underpinnings of performance, such as VO2max, heart rate and blood lactate. How much does mental fatigue affect performance? It’s tough to tell but the best estimate from the literature is few percent, which in a 100-mile run can mean ~45 minutes. That’s enough to pay attention to. Bottom line, mental fatigue matters. Although it’s hard to physiologically pinpoint why it hurts performance, you can do things to mitigate it.

Rocks in your pockets

Recently researchers at the University of Queensland used a directed focus group model (think of this as a group discussion with one person directing the conversation) consisting of elite athletes, coaches and staff to better understand their perceptions on the impact that mental fatigue has in elite sport. The researchers led these focus groups through a guided conversation specifically focused on their perceptions of mental fatigue, where it comes from and how the athletes are affected. The conversations were recorded and then analyzed for recurring themes. A word cloud model (where the number of times a word or phrase is represented by its size) was then generated from the transcripts in order to gain insight into the recurring themes. When discussing where mental fatigue actually originates from, the following word cloud emerged-

Figure 1- Word cloud representing the nature of perceived causes or induces of mental fatigue. (Russell et al 2019)

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It is easy to see that athletes, coaches and staff feel that the majority of mental fatigue comes from outside the field of play. The words- ‘environment’ and ‘other commitments’ emerge prominently as sources of mental fatigue. I see this time and again with the elite athletes I work with as they prepare for marque events such as the Western States 100 and UTMB. Inevitably, in the days leading up to these races, the athletes representing different brands are all in the same place at the same time. Wanting to leverage this proximity, the brands schedule photo shoots, product demos, booth appearances, social media takeovers and the like. At times, these ‘other commitments’ become overwhelming and have the potential to affect the athlete on race day. They are literally mentally fatigued from the commitments before the event even starts. I have always viewed this as ‘putting rocks in your pockets’ at the start of the race. No one would deliberately start a race with the tank half full by hammering a bunch of intervals the day before a race. Why would you do the mental equivalent by scheduling cognitive tasks in this same timeframe?

Mental fatigue is both chronic and acute

Another theme that emerged from the focus group conversations is that there is an acute aspect to mental fatigue as well as a cumulative aspect to mental fatigue. Acutely, athletes feel that fatigue from making many small yet critical decisions during the entirety of the event. The word ‘repetitive’ shows up prominently in the word cloud. Cumulatively over many days and weeks the participants felt that thinking and analyzing the sport and/or event has a tipping point. Step over that line and the over-analysis leads to burnout, disengagement, changes in mood and ‘going through the motions’.

Learning from these points, I have my athletes do the following to avoid expending any unnecessary mental energy-

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  1. Have your crew meeting early: It’s easy and even convenient to have your crew meeting the day before the race. But, save yourself the effort and have it in the few days before the race, even if it’s by phone or video conference. Your pacers and crew will thank you as they then have a few days to chill out and digest what is going on.
  2. Automate the number of repetitive tasks: ‘How far is it until the next aid station?’, ‘How many gels do I need?’ and ‘When is the cutoff?’ can easily be answered by a simple wristband on your arm with these details.
  3. Get the details out of the way early: I try and have my athlete pre-race meetings the week before the race (similar to the crew meetings), not the week of the race. This puts a deadline on the athlete to get their P’s and Q’s minded well in advance of the event. During this meeting, we’ll go over their pacing, nutrition plan, crew plan as well an any specific race logistics. After that meeting, the plan is ‘put in a box’ not to be opened up until race day (unless there is some significant course or logistical change). For any self coached athletes, the last point is poignant. Get your plan done early, then put it away! Obsessing over it and changing your pacing plan by 5 min here and there will not make a lick of difference. In fact, it likely will induce some unnecessary mental fatigue.
  4. Do not introduce new complexity into your race plan: You know that saying, “Don’t do anything new on race day?” While primarily meant to dissuade runners from pounding down something new at an aid station or donning a fresh pair of shoes on the start line, this advice also applies if you are adding new layers of complexity into a race situation. You think switching from vanilla gels to rasberry chews at Mile 30 is going to be a big deal? Probably not. But, if you don’t do these things in training, why even think about them and expend that mental energy during the race? Many of these micro decisions do not seem like a big deal at the time. But, repeated over the course of time, they add up and can cause unnecessary mental fatigue.

You can’t ignore the physical fatigue of an ultramarathon. Similarly, you shouldn’t ignore the potential for mental fatigue. Aside from the performance decline, it’s just plain embarrassing to leave your pack in an aid station, complete with the raspberry chews and double sodium electrolyte tablets.



  1. Russell, S., Jenkins, D., Rynne, S., Halson, S., Kelly, V.(2019) What is mental fatigue in elite sport? Perceptions from athletes and staff, European Journal of Sport Science, DOI: 1080/17461391.2019.1618397
  2. Van Cutsem, J., Marcora, S., De Pauw, K. et al. Sports Med (2017) The Effects of Mental Fatigue on Physical Performance: A Systematic Review. 47: 1569.

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