“That felt miserable! That was so much harder than last time. And slower!” Selena remarked as she walked off the track disappointed in her performance. She’d run 15 seconds slower in the 3,000m steeple than she did a few weeks prior. A performance at the time that she said “felt easy, I had a lot left,” and all of those other maxims coaches are used to hearing that entice us into thinking “how much faster can they go?” This isn’t a unique occurrence to Selena, it’s something every runner experiences. Why do some races, even much slower ones, hurt so much more? To find the answer, we need to turn to a tub of ice water.

In 1993, psychologist Daniel Kahneman and colleagues set out to understand how we perceive pain. He had a group of students submerge their hands in ice cold water for either 30 seconds or 90 seconds, rating their level of discomfort during the entire experiment. Finally, after completion of both trials, subjects were asked what trial–the 30 second or 90-second one– they would like to repeat. What Kahneman didn’t tell the subjects was that there was a bit of trickery involved.

During the 30-second trial, the temperature was kept at a constant chilly 14 degrees Celsius, but during the 90-second trial, for the first minute the temperature was kept at 14 degrees, but over the last 30 seconds, the temperature of the water was gradually raised by only one degree, so that it was slightly more tolerable but still very chilly. If we were rational and logical beings, we’d choose the shorter trial. After all, the peak discomfort levels were similar between both groups since the temperature was the same, but the longer trial made it where you spent 30 seconds longer at the same temperature and another 30 seconds at a just slightly warmer one. In other words, triple the time in the chilly water! But, logic didn’t prevail. Nearly 70% of the participants chose to repeat the long trial because they thought it was the less painful one.

What this experiment showed is what we now call the Peak-End Rule. Instead of being concerned with minimizing the total pain experience, our brains cheat and use a simple summation of the peak discomfort and the ending experience to tell us how painful the experience was. This occurs for a simple reason according to Kahneman, we have two different selves- an experiencing and narrating one. The experiencing self-refers to what happens in any moment, our instant appraisal of the world around us. In the ice water experiment, these are reflected by the instantaneous ratings of discomfort. The problem is this instant appraisal lasts only a few seconds before we move on to our next experience.

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Our narrating self doesn’t take every memory and paint a perfect autobiographical history but instead creates a messy, almost correct story, that is close enough for comfort, and is a flowing narrative that makes sense to us. During the aforementioned experiment, our narrative self-created a story that the longer time spent in the chilly water must have been less painful because it remembers the peak pain being similar, but the end of the experiment being less painful in the longer version. Thus, we defy logic and choose the longer segment.

When it comes to working out, we use the same mental processes. We don’t judge how difficult it is by a detailed analysis of how much pain we are in the entire time and the duration we experience discomfort. Instead, we use the average of the most painful moment, and the pain experienced at the end, which is still fresh in our mind. During the end of a race where we are competing for a win or a new PR, we have the added benefit of an extra hit of the body’s pain-killing and motivation inducing chemicals. Our attention is shifted away from the suffering and towards competing. So we often don’t “feel” as much pain. Even if we do, the instant gratification of a successful race as we cross the line creates a euphoria that functions much as raising the temperature of the water ever so slightly in the Kahneman experiment. In other words, how our race or workout ends has a lot to do with how hard we remember it.

We can take advantage of the Peak-End Rule in practice to manipulate how hard we remember a workout. In another experiment, this time using the dreaded and unpleasant colonoscopy, researchers compared a regular procedure with one in which they decreased pain during the last minute of the procedure by almost fully removing the colonoscope, but not telling the patient the procedure was done. The patients remembered the entire procedure as less painful and were more likely to have it done again.

When it comes to races, this phenomenon partially explains why we remember good and bad races differently. Through a combination of endorphins, hormones, and the pure elation of running a good race, we tend to mask, and then forget, how painful the successful races are. The “end” of the race, be that the last 100m or the joy in crossing the line, hurts less. When we cross the line after a bad race, our last finishing kick isn’t filled with the elation of running a PR or beating others, it’s filled with dread, sorrow, and dissapointment.

We see the same effect in workouts. If we finish a track workout with a gut-wrenching all-out 400m that leaves us gasping for breathe and splayed out on the track for several minutes, we’ll remember the entire workout as being more difficult, then if we did a similar 400m, but then finished the workout with a few easy controlled 200m repeats. In practice, we can actively take advantage of the Peak-End Rule by ending our workout with a set of moderate 100’s or even a tempo 800m at the end. We can trick ourselves into thinking we handled that workout well and had more left in the tank.

So what?

What’s the benefit of manipulating how hard we remember a workout or race? We can actually decrease the psychological stress that lingers after a really hard workout. Our stress hormones return to baseline quicker, allowing us to bounce back quicker. Psychologically, we aren’t left with a sense of dread, remembering the almost impossible workout we completed. Instead, we remember the hard, but doable workout, so that next time we have 400m repeats, our response isn’t worry or dread. We’re ingraining a message to be excited about completing a good hard workout.

So next time you have a hard workout, instead of going from intervals to laying on the track wiped out or slogging a cool down, add something else to the program. Famed coach, Mihali Igloi used to run 10x100m at a moderate effort to end. I watched Olympian David Torrance run an 800m in around 2:30 within seconds of finishing a hard track session. Were all of these individuals knowingly taking advantage of the Peak-End Rule? Probably not, but by eking out a little more adaptation and adding on some easy to moderate work at the end, they transitioned their body from stress to rest, and also fooled their memories into thinking it was a slightly easier workout than they remembered. By transitioning out of stress and into rest faster, we allow ourselves to handle a higher mental workload and decrease the chance of mentally driven burnout.

Are we using deception to trick our athletes or even our self? Well, humans evolved to use the peak-end rule to their advantage. Look no further than having a child. Thanks to our faulty memories and the joy that comes at the end, research shows we tend to forget just how painful childbearing is. Which is a good thing, because women might not want to have another after that experience. In many ways, a very hard race or workout is a minor example of the same phenomenon. If we remembered how bad the really tough races hurt, we just might not come back for more.

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