How Positive Reinforcement May Improve Physiology and Hormones

Fascinating studies from rugby show that positive reinforcement before and after matches can increase testosterone and reduce cortisol, along with improving performance. What are the implications for how we discuss training and racing?

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I recently saw some interesting posts on social media. I am apparently now starting articles like grandma starts phone conversations that rapidly turn problematic.

But this is cool, I promise. Amazing coach and writer Steve Magness tweeted about studies from rugby looking at hormonal responses to coaching interventions. So I asked my wife/co-coach Megan to print the full articles and started going through some of the most wonderfully fun research studies ever written. Side note: I strongly recommend marrying someone who plans to continue with school into their 30s. One way to access my heart is via Pubmed access.

The part of these studies that I think is revolutionary isn’t about coaching. It’s about how we set intentions to process the ups and downs of our own athletic lives. Ted Lasso isn’t walking through that door. Even if you have a coach that ascribes to these principles, they’re one of many voices in your head for long-term internal processing.

And the studies show that the internal psychological processing may have a massive impact on our physiology (Megan and I talk about the studies in more detail on our podcast). For optimal long-term growth, we may have to learn to be our own Ted Lassos.

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Positivity and trail running

The Science Of Positive Reinforcement

Let’s start with a 2012 study in the journal Physiology & Behavior, which looks at pre-match interventions in elite rugby players. Twelve male athletes (average age 21.8) underwent three test conditions, each taking 15 minutes:


  • Condition One: video clip of their successful play with positive coach feedback
  • Condition Two: video clip of successful play by opponent with cautionary coach feedback
  • Condition Three: “player left alone to self-motivate”


That last one sounds like a euphemism. Someone needed to say it. 

Conditions One and Three were re-tested. Doing Condition Three multiple times? Oh, to be 21 again.

Researchers measured salivary free testosterone and stress hormone cortisol before the intervention and before the game (after the intervention). They were also rated on their performance by the coaching staff.

I always like to take a step back after laying out the ground rules of the study. What do you think happens to those variables? My guess: well, it’s purely psychological, so maybe some minor changes. Even as a proponent of self-talk and swag, I was SHOCKED to see the results.

The two trials involving positive feedback led to 11.8% to 12.5% increases in free testosterone! Those trials also involved best game performance by a significant margin. Meanwhile, the cautionary feedback resulted in a 17.8% increase in stress hormone cortisol, and worse game performance. 

The authors caution that this study just shows a correlation, with a more robust study needed to draw results about causation. Also, the study was only conducted in male athletes, which is a major shortcoming, but it’s likely that the same stress-response mechanisms apply. 

How fun is that? Just by hearing that you’re a boss, backed up by some video proof, you are more likely to play like the boss you are. I love when confirmation bias involves getting to tell people they are freaking bosses. You could imagine these results applying even more in running, where there are fewer variables related to strategy or discipline that might reward negative feedback.

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Post-Match Positive Reinforcement

Pre-match interventions are awesome, but what I most wanted to see were post-match interventions. Right before a match (or run) is a limited window to act, and it might be impossible to get hyped with positive thoughts when your run is right after a business meeting or changing a diaper. But the processing of the game/run happens over many hours/days, so it might be an even greater opportunity.

Enter another 2012 study in Physiology and Behavior. Twelve male rugby players did four one-hour video sessions with a coach the day after matches:


  • Two video sessions involving player mistakes with negative coach feedback
  • Two video sessions involving player successes with positive coach feedback


The researchers measured four variables in the following week: testosterone and cortisol responses to a pre-game stress test, pre-game testosterone, and game performance. What do you think happened? Prepare to have your socks blown off all the way to Kansas! 

The stress test resulted in a 36-42% increase in free testosterone in the positive feedback trials, compared to a -3-16% change in the negative feedback trials. Maybe Frank Thomas and Doug Flutie got negative feedback before they agreed to star in those sketchy supplement commercials that air non-stop on ESPN. Pre-game testosterone in the positive reinforcement group was way higher too, and game performance was stunningly better. 

A 2017 review in the Journal of Strength and Conditioning research summed it up: “psychosocial interventions that create a positive environment may elicit a hormonal response that is associated with favorable performance outcomes.” That review emphasizes that the changes occur without any metabolic stress. In other words, the only work that’s being done is chemical via the endocrine system with the nervous system mediating those changes, but those chemical shifts can fundamentally alter performance.

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Here’s a Fun Study

While you’re here, let’s quickly look at one more very sexy science study from the world of rugby. For fun! And context! BUT MOSTLY FUN. A 2012 study in Hormones and Behavior had athletes watch 6 different 4-minute clips before doing a 3-rep maximum squat protocol, measuring testosterone and cortisol before and after the clips. Now for the fun part: the clips were sad, erotic, aggressive, training motivational, humorous, or a neutral control clip. I also got hyped by the inclusion of erotic clips. Porn, but for science. 

Testosterone increased from the aggressive, erotic, training motivational, and humorous videos. It dropped after the sad video. The aggressive video also produced an increased cortisol response. Squat performance increased after the aggressive, erotic, and training videos, with testosterone changes correlating with squats within individuals. 

Big conclusion: if you can’t get positive reinforcement, try pornography. No, that’s not it. Instead, that study underscores the importance of psychosocial interventions and intentions, and how they may work in complex ways. It’s not as simple as “be told you are awesome to become awesome.” The literature on positive reinforcement in other contexts backs that up, with various findings depending on the study structure, but general favorability in most situations.

RELATED: Positivity Training: Four Mental Keys

Posivity mental health hormones trail running science

Performance and Psychosocial Interventions

If performance is a math equation, the most important variables may be missing from many curricula focusing on the physiology of the aerobic system or metabolic processes. How does the athlete feel about themselves and what they are doing? The answer to that question can have profound implications for long-term growth. 

Yes, these are just a couple studies, and they’re conducted in a sport that is pretty far from endurance running. There weren’t female athletes involved (it’s hard to control for hormonal responses within the menstrual cycle), but the processes should be similar based on other studies (see this 2016 study in Hormones with female participants). And I haven’t seen this research validated by a ton of other protocols. 

But if there is any hormonal and performance influence from positive reinforcement, even a microscopic one that fluctuates over time, it has the potential to fundamentally alter an athlete’s trajectory. Small, fleeting changes in the endocrine system may create a positive feedback loop, leading to better performance and better hormonal state. Both shift how the body adapts. Eventually, the best, idealized version of yourself may just become the new baseline for who you are. And the best, idealized version of that new you could become a champion in ways that would be absolutely unthinkable at the outset.

Ever since there was injectable synthetic testosterone, athletes have been cheating for championships. Basically all steroids work on that same principle, messing up the body and the integrity of sports in the process. These studies indicate that for some athletes, there may be a natural, legal, healthy steroid available to everyone.

Call it Lassolone (20cc of BELIEVE directly into your frontal lobe). Believe in your capabilities, with evidence to back up that belief, and you have a lot better chance of becoming something that may be unthinkable in the moment. What that means in practice: focus and replay your successes, using your failures for the necessary learning without reading into them too much. Practice positive self-talk, using each run as an opportunity to be your own coach. Remember that your fitness is your best day, and everything else is just an opportunity to learn. Be curious, not judgmental. And if your mentors project their insecurities onto you by screaming for no good reason or making you feel unworthy for any reason, get new mentors.

As athletes, I don’t think we set our theoretical ceiling. Genetics may ultimately have the final say. But I am almost certain that very few athletes ever reach their true genetic ceiling. Instead, they hit some resistance and decide it’s a ceiling, when it’s just a pocket of thicker air. 

So…..Hey! Listen up. 

You got this. Look how many times you have gotten past similar resistance before! You are undeniably, objectively a badass freaking boss and you are JUST GETTING STARTED.

Now let’s go see where the limit is. And if that air won’t budge…

Let’s see if we can shatter some damn ceilings.


David Roche partners with runners of all abilities through his coaching service, Some Work, All Play. With Megan Roche, M.D., he hosts the Some Work, All Play podcast on running (and other things), and they wrote a book called The Happy Runner.

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