Hello and welcome back to the Endurance Lab newsletter.

In last week’s newsletter, I discussed sodium bicarbonate, how it buffers hydrogen, and whether it works for longer distance events like the 5k (the answer is yes!) This week, we’re going to move away from physiology a bit and talk about something runners love to say but rarely define: mental toughness.

When someone runs well, we say they’re tough. When someone falls apart, we say they need to work on their mindset. Basically, mental toughness becomes the explanation for everything we can’t explain with VO2max, lactate threshold or running economy.

But what if mental toughness is not simply your willingness to hurt? What if it is, at least in part, your ability to control the thoughts and cues that change how hard the exercise feels?

This newsletter will discuss why you stop exercising, how mental fatigue can impair performance before you even start, and a simple self-talk protocol that improved endurance performance by roughly 18%. More importantly, I’ll give you a few ways to actually practice this instead of just telling yourself to “be tougher.”

Also, who doesn’t want to run faster? 2 easy ways. Join our team to be coached by yours truly at https://www.endurancelaboratory.com. Then go to www.bicarb.shop and use Code "DRE" for 10% off!

Why Do You Stop?

There are many explanations for why you stop exercising, but some of the most notable are the accumulation of detrimental metabolites, central governor theory, structural damage preventing contractions, neural fatigue, ionic imbalance and or changes in calcium transients. Frankly we don’t know exactly. 

However, these explanations become a bit confusing when you consider the following: during your kick, you can increase your pace when verbally motivated by onlookers and those cheering. How can this be? How do you kick at the end of a race, or magically find another gear when runners around you make moves or start to pass? 

The psychobiological model of endurance performance proposes a different explanation. Exercise ends when one of two things happens: 1) the effort required becomes greater than the amount of effort you are willing to give, or 2) the effort feels so extreme that continuing seems impossible [1]. This is at the heart of the central governor theory; the idea that you should stop to protect your survival/well being.

In other words, performance is determined by the interaction between perception of effort, how hard the exercise feels, and potential motivation, how much effort you are willing to invest. So two things: perception and motivation.

Keep in mind, this does NOT mean fatigue is imaginary. Rising temperature, low glycogen, muscle damage, ventilation, and the actual force required to hold pace all contribute to effort. The point is that your brain still has to interpret those signals, and two people can experience the same pace, heart rate and blood lactate, but interpret the effort differently.

Mental Fatigue and Effort

Before we discuss how to improve this, consider a recent study from Mortimer and colleagues [2]. They recruited 164 athletes and separated them into four groups: mental fatigue, physical fatigue, combined mental and physical fatigue, and a control group.

Mental fatigue was induced using a difficult 15-minute cognitive task. The physical fatigue condition completed 90 seconds of burpees. Afterward, everyone completed a throwing task and then performed burpees to failure.

Guess what? The mentally fatigued athletes performed worse. They were less accurate on the throwing task and completed fewer burpees than the physical fatigue and control groups. Only 15 minutes of difficult thinking was enough to impair both skill and endurance.

The strangest result was that the mental-fatigue-only group performed slightly worse than the combined group. In other words, doing 90 seconds of burpees after the cognitive task seemed to offset some of the negative effects of mental fatigue. The authors were cautious with this interpretation, but it raises an interesting possibility: a physical warm-up may help pull you out of a mentally fatigued state.

Practically, this matters for anyone who trains after work. You might leave your office with completely fresh legs, but after eight hours of emails, meetings, grading, studying and making decisions, your brain is not fresh. Then, you sit in your car, scroll your phone for 20 minutes, and wonder why you’re absolutely suffering during your workout.

Consider the two things at the beginning: perception and motivation. Motivation is compromised, but so too is perception of effort. It will literally feel harder.

This doesn’t mean you need to quit your job to run well, what it means is that you should consider some strategies to prevent this pre workout fatigue. Maybe consider your drive to the workout as part of the workout. Consider reducing unnecessary decisions, get off your phone, have a snack, prepare at the end of the workday, and consider a longer warm up or a gentle first rep before ripping.

So how do we change your perception? One of the simplest strategies is self-talk. It sounds so simple, but we don’t do it. It’s literally what it sounds like:

“I feel awful.”

“I can’t hold this.”

“There are still three reps left.”

These statements do not simply describe the workout. They direct attention toward threat, discomfort and the distance remaining. Basically, you are giving your brain a running commentary on why it should stop.

Blanchfield and colleagues tested whether changing that commentary could improve endurance performance [1]. Twenty-four participants completed a cycling test to exhaustion at 80% of peak power. Half of them then completed a two-week self-talk intervention while the control group continued normally.

The intervention was surprisingly practical. Participants identified the things they already said during the first test, selected four motivational statements, and then practiced them during at least three aerobic workouts. Two statements were designed for the early-to-middle portion of exercise and two were reserved for the end, when exhaustion was approaching. If a statement felt useless, they replaced it.

After two weeks, time to exhaustion increased from 637 to 751 seconds in the self-talk group, about an 18% improvement. The control group did not improve. Even better, 10 of the 12 participants in the self-talk group lasted longer.

The mechanism is the most interesting part. At the same point in the test, RPE decreased from 7.3 to 6.4 after the intervention. Heart rate and blood lactate did not meaningfully change. The exercise was still physiologically demanding, but it felt more manageable, so they could sustain it longer.

Self-talk did not eliminate the fatigue at all, but it did change their perception of that fatigue. Again, perception.

Alright, now this doesn’t mean we’re going to go to the gym and yell “LIGHT WEIGHT!” or some other weird remark. Instead the phrases need to be personal, believable, and relevant to the actual stage of the workout.

Step 1: Record what you already say. During your next hard workout, pay attention to the first negative thought that shows up. Write it down after the rep. Do not judge it. You are simply identifying the language that currently controls your attention.

For me this is usually quite negative or involves a very low sense of self. Not good. 

Step 2: Build two early cues. Early in a workout or race, the goal is control. Task orientation means giving attention to controllables, pace control, rhythm, mechanics, rather than threat thoughts. Useful cues might be “deep breaths”, “relax the hands”, or “one rep at a time.”

Step 3: Build two late cues. Near exhaustion, different mechanisms come into play because you are no longer trying to convince yourself that the effort is easy. It’s not. It’s going to hurt and it’s supposed to. The cue should emphasize continuation: “push through this,” “stay here,” “one more minute,” or “you’ve done this before.”

Step 4: Practice them. The participants in this study didn’t invent these phrases during test day.  They practiced for two weeks and used the statements during at least three sessions. Mental skills are still skills, and if you only use them when you are already panicking, they’re not going to work.

Step 5: Replace what does not work. If a phrase feels corny or unbelievable, throw it away. “I feel amazing” is probably useless when you clearly feel terrible. “I can hold this for 60 more seconds” is specific, believable, and gives your brain a manageable endpoint.

The last paper takes this idea one step further. Blanchfield and colleagues had 13 participants cycle to exhaustion while subliminally exposing them to happy or sad faces [3]. The images appeared too quickly for participants to consciously identify them.

When exposed to happy faces, participants cycled 178 seconds longer, about 12%, and reported lower RPE at comparable time points. Thing about that. They were able to push for 3 more minutes despite their heart rate and blood lactate at exhaustion were virtually identical.

The broader point is that your environment changes the way effort is interpreted. The music you hear, the people around you, the words on your screen, and the things you consume before racing may shift attention toward action or toward threat. You probably do not need inspirational posters all over your house, but reading stressful emails and doom-scrolling ten minutes before a race or crucial workout probably isn’t helping.

If you want something simple to implement, here it is:

·       Protect the 30-60 minutes before important workouts from mentally exhausting work when possible.

·       Stop scrolling before training.

·       Use the warm-up to transition from thinking to moving before judging how you feel.

·       Choose two early task-oriented cues for pace, rhythm or mechanics.

·       Choose two late cues focused on commitment and continuation.

·       Practice the same four cues for two weeks during hard workouts.

·       Break difficult sessions into the current rep, minute, hill or landmark. I often tell people to be a goldfish.

·       Afterward, keep what worked and replace what didn’t.

Mental toughness isn’t pretending that exercise doesn’t hurt. That’s just silly and negligent. Rather, it’s the ability to prevent discomfort from controlling attention, language and decision-making.

Mental fatigue can impair performance before the workout even begins, and self-talk can reduce perception of effort without changing heart rate or lactate. Positive and action-oriented cues may even influence performance without conscious awareness.

So yes, mental toughness is trainable. But you train it by practicing how you respond to effort rather than waiting until race day and hoping you become a different person.

Cheers mates.

References:

1. Blanchfield, A.W., et al., Talking Yourself Out of Exhaustion: The Effects of Self-talk on Endurance Performance. Med Sci Sports Exerc, 2014. 46(5): p. 998-1007.

2. Mortimer, H., N. Dallaway, and C. Ring, Effects of isolated and combined mental and physical fatigue on motor skill and endurance exercise performance. Psychol Sport Exerc, 2024. 75: p. 102720.

3. Blanchfield, A., J. Hardy, and S. Marcora, Non-conscious visual cues related to affect and action alter perception of effort and endurance performance. Front Hum Neurosci, 2014. 8: p. 967.

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