A few years ago, I did 12 weeks of “brain endurance training” as part of my preparation for the Ottawa Marathon, then wrote about the experience for Runner’s World.

The training program was based on ideas developed by Samuele Marcora, a researcher at the University of Kent. By forcing yourself to perform mentally fatiguing tasks, he argued, you could improve the brain’s ability to resist mental fatigue—just as exhausting yourself physically in training builds your physical endurance.

I recently got an e-mail from a friend who is preparing for the Tokyo Marathon next February. He’d recently seen me describe my experiences with braining endurance training in this talk that I gave at last year’s Endurance Research Conference. He’s interested in pushing his limits and trying new ways to improve, and wanted to know whether I thought brain training was worth a try, and if so, how to go about it.

I’ve been putting off my reply for a few weeks now—because it’s a tricky question. I often write about neat ideas with future potential; but in practice, condemning someone to spend hours clicking buttons in response to arrows and letters and shapes on a computer screen (as I did) is not something you do lightly.

So here, in the end, are the points I want to convey:

1. There is preliminary evidence that brain endurance training works. In Ways to Make Running This Winter More Enjoyable, Marcora presented results from a study funded by the British Ministry of Defence that seem almost too good to be true: a 126-percent increase in time to exhaustion among untrained subjects doing a combined mental and physical training routine, compared to just 42 percent among those doing only the physical training. Lots more validation needs to be done, but it’s encouraging.

2. You don’t get benefits just by, say, doing crosswords and multiplying large numbers in your head. One of the key mental demands of endurance exercise is “response inhibition”—the ability to resist the urge to pull your finger out of a candle flame (or to slow down in a race). Brain endurance training focuses on specific endurance-linked aspects of mental fatigue.

It’s worth noting that one of the main criticisms of the lucrative brain training industry is that its supposed benefits don’t generalize to everyday life. You get better at whatever specific task you’re training (e.g., you become a crossword whiz), but you still can’t find your car keys. I think it’s still an open question whether computerized brain games that challenge response inhibition can generalize to improved running performance—but that’s certainly a better bet than brain training modules that target completely different aspects of cognitive performance.

For that reason, I don’t think it’s worth doing brain endurance training without using a properly validated set of cognitive challenges. And, on a practical level, I haven’t yet found anything outside a research setting that makes these specific brain challenges accessible to the general public. That, to me, is the strongest argument against trying this form of brain endurance training right now.

3. Maybe training for a marathon (or doing other serious endurance training) is all the brain training you need. After all, sustaining the focus required for long training sessions is undeniably mentally taxing. A Part of Hearst Digital Media found that elite cyclists did indeed have better response inhibition than amateur cyclists, and were better at maintaining their performance when mentally fatigued.

Is this because the elites were born with better brain endurance, or because their training made them that way? And even though the elites were already good, could they get better? At this point, no one knows. But it’s another reason to suspect that adding brain endurance training won’t have the same spectacular results in trained athletes that it appears to produce in untrained subjects. That’s not surprising—after all, virtually nothing produces big gains in already-well-trained athletes.

So, to sum up those first three points, I suspect brain endurance training has real effects, but it’s probably not worth trying unless you have the tools to execute it properly, and it may well have diminished or marginal effects in well-trained athletes.

Where does this leave us? For my money, the brain intervention with the best ratio of potential outcome to time and effort invested is motivational self-talk, which involves deliberately learning to control the inner monologue that tells you to give up or keep pushing.

Marcora published some promising results on self-talk back in 2013. Since then, he and others have published further findings, including a study this fall from Stephen Cheung’s group at Brock University that found that cyclists could push themselves to a higher core temperature in hot conditions after a simple self-talk intervention.

The nice thing about self-talk is that it’s not as arduous as brain endurance training. For what it’s worth, here’s a detailed description of the two-stage self-talk intervention used in Marcora’s 2013 study:

During stage 1, participants were introduced to the concept of self-talk and provided with a workbook in which they highlighted any self-talk statements that they had used in the preceding TTE [time-to-exhaustion] test. From this pool of self-statements, participants identified up to five that were deemed to be motivational and compared them to a set of 12 prelisted motivational statements (e.g., “drive forward” and “you’re doing well”) generated from the existent self-talk literature. From these two lists, participants were requested to select four statements that would optimize their performance during a TTE test identical with the one previously carried out. It was instructed that two of these statements should be relevant to the early–mid stage of such test (e.g., “feeling good”), with the remaining two being more applicable to the last stage of the test near exhaustion (e.g., “push through this”). This approach was chosen so as to identify the contextual influence of verbal statements (27) on specific stages of the TTE test.

Stage 2 was a familiarization phase in which participants were instructed to continue with their own training while using their selected statements, during a minimum of three aerobic exercise sessions over the 2-wk period. After each aerobic exercise session, participants completed a workbook protocol to assist them in assessing the use and efficacy of each of their four chosen statements during the session. Effective statements were noted and used in the subsequent aerobic exercise sessions, whereas ineffective statements were either rephrased or replaced with a more suitable statement (as deemed by the participants). This process was designed to ensure that participants were comfortable using their four motivational self-statements when they performed the second TTE test (posttest).

If I were to sum all that up in a few words, it would be to be conscious of your internal monologue, and practice shaping it in a positive way. Like every other aspect of training, don’t expect to execute it in a race if you haven’t mastered it in practice.

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