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Episode 185: Smiling/Will Hicks
A brief synopsis of the episode's main discussions and takeaways as well as extended references
Jeff Sankoff
December 05, 2025
How great is it that smiling actually works to improve your endurance performance? I for one was very happy to learn this. Though the caveat was learning about how air pollution is becoming a growing health concern.
Table of Contents
Smiling to perform
When we set out to answer the question about whether or not smiling improves performance we did not realize that there was quite so much science that had been done on the subject. Best of all, we were shocked to see how most of it was so positive with objectively measurable results. The power of positivity manifests in a few important ways-by decreasing the perception of effort and by actually decreasing the physiologic markers of strain so that you can put out the same effort with less sensations of distress. How does smiling do all of this? Basically it is all through dopaminergic pathways in the brain. Dopamine is the reward neurotransmitter and it is amped up when we are happy or just when we smile because ever since we were little we have been conditioned to know that if we are smiling…we ARE happy. The other means by which smiling seems to help is through a decrease in stress hormones. And it isn’t just endurance sport either, studies have shown that smiling at work improves worker output and job satisfaction. So turn that frown upside down and reap the benefits!
Will Hicks-co-founder of Air Track
About Will according to Will: Dr Will Hicks is the Co-Founder and Chief Scientific Officer of Air Aware Labs, which he started with his co-founder Louise Thomas. Together, their mission is to help people understand and reduce their exposure to air pollution. With a PhD from Imperial College London, Will has spent years measuring and modelling traffic emissions and assessing indoor air quality. He and the team recently launched AirTrack, a mobile app that combines cutting-edge modelling with real-world data to help individuals, businesses, and governments make healthier choices. Outside of work, Will’s currently training for the Loch Ness Marathon - where at least the air quality should be excellent.
Will Hicks of AirTrack
Ever thought about how much air pollution is ruining your outdoor vibe? Well, welcome to the reality check that is this episode of the Tridoc Podcast. We’re joined by Will Hicks, your new best friend when it comes to air quality awareness. This guy’s on a mission to make sure that when you lace up your sneakers, you’re not just running into a toxic cloud of doom. The conversation kicks off with the basics of air quality metrics, but don’t worry, it doesn’t get too science-y—unless you count the moment we discover that 24 micrograms of nitrogen dioxide can actually ruin your marathon pacing. We’re talking about real, actionable insights into how to dodge the worst air pollution when you're out there doing your thing. Will explains how the Air Track app uses fancy algorithms and satellite data to give you hyper-local air quality readings. No more guessing what you’re breathing in while you’re out for your morning jog. And let’s not forget the wild implications of air quality on athletic performance—because who wants to be gasping for air while trying to chase down that elusive “fastest runner” title? In short, this episode is a must-listen for anyone who cares about their lungs and their legs. Get ready to turn your training into a pollution-evading adventure!
Episode takeaways:
Air pollution insights are now super localized thanks to AI and satellite data, allowing us to understand our specific exposure levels.
The AirTrack app is a game changer for athletes, integrating air quality data to help you choose the best times and routes for outdoor activities.
Smiling during exercise can actually enhance performance by reducing perceived exertion and boosting your mood
Even in winter, air quality matters, so remember to check your local air quality index before outdoor workouts, especially after wildfires.
Positive thinking, like smiling, has scientifically proven benefits, including better performance in workouts and overall well-being—science backs up the power of positivity!
It's essential to monitor both outdoor and indoor air quality; cooking and cleaning can pollute your home, so ventilate wisely to stay healthy.
References used for the MMB
Smiling Is a Powerful Mental Tool for Endurance Athletes
Article by Jim Taylor, Ph.D.
Key Points:
The author shares an anecdote about a professional triathlete they worked with in the past, whose physical and psychological transformation from forcing a smile during a rough workout helped her to relax and show improvement in the remainder of her training.
The writer defines smiling as a motor skill that involves raising the sides of one’s mouth.
The article notes that research indicates that smiling (both natural and forced) can help to elevate one’s mood because
1) We are conditioned to the positive effects of smiling, and
2) Smiling causes our brains to release dopamine, endorphins, and serotonin
The general benefits of smiling include: feeling happy, reducing stress, lowering blood pressure, strengthening the immune system, and easing pain
“Embodied emotions” is the idea that our emotions and physiology have a reciprocal relationship, which makes it difficult for our emotions to be inconsistent with the body’s physiological messages.
Smiling produced lower O2 consumption and energy expenditure among runners compared to frowning. Smiling has also been found to reduce perceived effort and exertion pain relative to frowning. These are qualities that are beneficial to athletic performance.
The Effects of Smiling and Frowning on Perceived Affect and Exertion While Physically Active
Philippen et al. 2012
Key Points:
While studies previously demonstrated the influence of controlled facial expressions on affective states, no study examined it’s influence under physical activity.
This study assessed whether deliberately adopted facial expressions have an effect on affective states and perceived exertion during physical activity.
Participants ' scores on the Feeling Scale (FS) and the Ratings of Perceived Exertion scale (RPE) were compared between conditions of facial expressions (smiling vs. frowning), while cycling at 50 to 60% of max HRR and while in rest.
Statistical findings indicate that participants felt more positive when deliberately smiling than when frowning.
Participants also reported perceiving less exertion in the smiling condition compared to the frowning condition.
More positive effects of smiling were present at both rest and physical activity relative to the frowning condition.
Study suggests that facial feedback effects exist during physical activity, pointing to the potential that positivity may enhance performance due to smiles (associated with positivity) inducing less perceived exertion.
Methods: Dutch students (N=34, n=18 women, n=16 men, avg. age 21.91, mean physical training experience 13.9 years) were recruited. 7 Euros rewarded for participation. Participants were asked to smile or frown naturally. Explained to bring eyebrows together and down for a frown. Told they were observing the effect of smiling/frowning on HR. A bicycle ergometer was used for physical activity. Exercised at 50-60 max heart rate reserve. HR was measured using a wrist monitor. Estimated Max HR = 220 - (participant age). One-Questionnaire Feeling Scale (FS) was used to assess affective response. Perceived exertion was measured with 15-point Borg’s Ratings of Perceived Exertion scale (RPE). Exit interview with demographic questions.
Results: ANOVA showed significant effect for facial expression, p <0.001. Mean FS score of the smile conditions was 3.15 (SD = 0.91) and frown conditions was 2.32 (SD = 1.35). Results indicated that participants felt better while they were smiling than while they were frowning. Significant effect for physical activity observed (p = 0.001) with mean FS score of the two activity conditions (smile and frown) being 2.51 (SD =1.12) and the two rest conditions (smile and frown) being 2.96 (SD = 1.10). Results indicated that participants felt better when they were at rest (just sitting on the bike) than when they were active (cycling). No interaction effect was found. Significant main effect for facial expression (p = 0.001) found. Mean RPE score of the two smile conditions was 9.13 (SD = 1.09) and two frown conditions was 9.71 (SD = 1.36). Results indicated that participants perceived less exertion when smiling than when frowning. Furthermore, there was a significant main effect for physical activity (p < 0.001). The mean RPE score of the two activity conditions was 11.79 (SD = 1.87) and the two rest conditions were 7.04 (SD = 1.09). Results showed that participants perceived less exertion while just sitting on the bike than while they were cycling. No interaction effect was found.
Smiles affect response to stress
Article by Harrison Wein, Ph.D.
March 13, 2018
Key Points:
In stressful situations, the hypothalamic-pituitary-adrenal (HPA) axis mediates the release of glucocorticoid hormones by the adrenal glands
This article notes a study conducted at the University of Wisconsin-Madison.
This study examined the effect of evaluator’s facial expressions (reward, affiliation, or dominance) on the glucocorticoid cortisol and ECG of 90 male college students who were asked to give short speeches.
The goal was to understand whether the HPA axis responds to nonverbal cues.
Dominance smiles increased levels of cortisol and heart rates in participants, while the reward and affiliation smiles buffered the effects of stress, lowering the participants’ cortisol levels to baseline within 30 minutes of their speeches.
People show physical responses to non-verbal social cues.
This study suggests that external positivity from evaluators such as coaches, parents, and/or peers may contribute to a more relaxed state during performance, such as speeches. Such effects may be observed in different contexts, including sports performance.
Since women were not included in this study. Women may respond differently to nonverbal social cues compared to men.
Dopamine: The Neuromodulator of Long-Term Synaptic Plasticity, Reward and Movement Control
Speranza et al. 2021
Key Points:
Dopaminergic systems are central for orchestrating neural mechanisms of learning, memory, pursuit of rewards, movement control, hormone release, and emotional balance.
Dopamine, a neurotransmitter released in response to reward-related stimuli, is not only significant for motivation, motor control, and stimulus-reward learning processes, but also modulates synaptic plasticity (the change of strengths of neuron connections) through its actions on dendritic spines.
Any stimulus, object, event, activity, or situation that is capable of generating happiness and positive reinforcement can be considered a rewarding stimulus.
Rewards 1) induce behavior, 2) elicit movements towards the desired object, and 3) arouse emotions, such as pleasure, disgust, pain, and fear.
The most consistent Dopaminergic system resides in the midbrain, where Dopamine is important for excitement, movement, mood, and the execution of activities that require immediate decisions and learning through reward.
Dopamine levels continuously signal how optimal a situation is for obtaining a reward, helping individuals to decide and motivate themselves to achieve a goal and helping them learn from missing rewards.
The information in this article suggests that dopamine’s role in experience-dependent neural rewiring explains the biological mechanism by which positivity and reward states may improve performance by motivating individuals to achieve a goal.
Dopamine in Sports: A Narrative Review on the Genetic and Epigenetic Factors Shaping Personality and Athletic Performance
Kinga Huminska-Lisowska, 2024
Key Points:
While more research is needed to directly link genetic polymorphisms to personality traits and athletic success, this paper suggests that dopamine-related genes may shape athletic abilities
Studies have identified specific single-nucleotide polymorphisms (SNPs) in dopamine-related genes that are linked to personality traits deemed crucial for athletic performance, such as motivation, cognitive function, and emotional resilience.
Through this narrative review, the authors examined how genetic variations influence athletic success through dopaminergic pathways and environmental interactions.
According to the paper, many theorists and practitioners argue that the athlete’s psychological attributes and physical prowess are both essential for success in high-level competition
The paper notes that “winning with the mind” involves mental toughness through cognitive decision-making factors that promote resilience, determination, and the ability to overcome setbacks, which is shaped by both inherent predispositions and external experiences.
“Genetic factors such as polymorphisms in dopamine-related genes, including dopamine receptor genes (DRD), dopamine transporter gene (DAT1), and catechol-O-methyltransferase gene (COMT), have been extensively studied for their role in athletic performance and psychological traits, including impulsivity, stress tolerance, and goal-oriented persistence.”
Higher dopaminergic activity is linked to effort-based decision making, higher motivation to train, faster skills acquisition, and enhanced focus and persistence
COMT Val158Met rs4680 and BDNF Val66Met rs6265 are associated with increased focus, stress resilience, and conscientiousness, which may be beneficial to performance, especially in martial arts.
DRD3 rs167771 is associated with higher agreeableness, benefiting teamwork in sports like football.
The nuance of how each personality trait affects sports remains underexplored due to the varying demands of each sport that may cause personalities to interact uniquely with performance
However, conscientiousness, emotional stability, and extraversion are noted as important predictors of athletic performance
Extraversion, characterized by sociability, assertiveness, and enthusiasm, also plays a significant role in athletic performance, particularly in team sports, where frequent and effective communication with teammates, coaches, and competitors fosters a positive atmosphere that enhances performance
NBA players with higher levels of extraversion have been observed to have enhanced pain tolerance, which is beneficial in sports requiring physical and mental endurance
Openness to new ideas and creativity is essential in athletic performance, where willingness to try new approaches can lead to improved learning and skills
Positive association has been observed between the openness score of sports climbers and boulderers and their climbing performance
Dopamine is central to the brain's reward system, so variations in these dopamine-related genes can influence an athlete's motivation and drive.
Genetic factors can affect an individual's ability to cope with the stress associated with intense training and competition.
Dopamine-related genes are involved in cognitive processes crucial for sports, such as attention, focus, and decision-making.
Positive Performance States of Athletes: Toward a Conceptual Understanding of Peak Performance
Jackson & Roberts, 1992
Key Points:
I did not have full access to this paper
This study administered a questionnaire to 200 collegiate athletes to assess mastery and competitive goal orientations to ascertain the relationship between peak performance, flow, goal orientation, and perceived ability.
The authors’ hypotheses that the psychological process of flow underlies peak performance and is associated with a mastery-oriented focus and high perceived ability were supported.
Analysis of the athletes' best performances indicated that a total focus on performance and other characteristics of flow were key to the perception of a superior state of functioning, while overconcern with the outcome, reflecting a competitive orientation, was often associated with the worst performances
This paper suggests that a more positive outlook on performance and outcomes may contribute to better results
How and why could smiling influence physical health? A conceptual review
Cross et al. 2023
Key Points:
I did not have full access to this paper
This literature review paper assessed the relationship between naturally occurring and experimentally manipulated smiles and physical health as it relates to the facial feedback hypothesis, the undoing hypothesis, the generalized unsafety theory of stress, and the polyvagal theory.
The paper’s abstract reports that both naturally occurring smile studies and experimentally manipulated smile studies consistently suggest that smiling may have health-relevant benefits, including beneficially impacting our physiology during acute stress, improving stress recovery, and reducing illness over time.
Attributional style and athletic performance: Strategic optimism and defensive pessimism
Gordon 2007
Key Points:
Potential gains from the power of “positive thinking” have been reported in literature and popular press.
Most of the research in this area has examined optimism as a personality contrast associated with positivity to measure its effect on different behaviors and outcomes.
While study 1 showed a significant positive relationship between optimism and performance in soccer loss, differences in performance were not observed during a win.
Furthermore, both a positive relationship (more assists and steals) and a negative relationship (fewer rebounds and more fouls) observed between optimism and performance.
In the second study, the observed negative relationships were a function of athletes attributing negative outcomes to lack of effort (defensive pessimism) as opposed to the lack of ability (depressive pessimism).
The inconsistency of results and different forms of pessimisms suggest that individual thought processes of pessimism may need to be understood to clarify the role of positivity in sports.
Methods: Study 1: Intramural soccer players from the upper midwest (N=20) recruited. Performance data collected from 8 games. Coded as goals, fouls, attempted passes, and completed passes. Players participated in 5-8 of those games. Attributional Style Questionnaire (ASQ) used. Study 2: Female DII basketball players (n=18) completed ASQ and Life Orientation Test (LOT). Relationship between scales and performance assessed.
Results: ASQ measure of optimism and soccer performance showed significant positive correlation with optimistic participants showing better performance during loss compared to pessimists. However, no difference between groups during wins. Basketball study showed less consistent results. “Significant positive relationships were found between the composite optimism score on the ASQ and assists r(16)=.72, p<.002 and steals r(16)=.73, p<.001. However, contrary to predictions, optimists had fewer rebounds, r(16)=−.53, p<.035 and were more likely to foul out of games than were pessimists, r(16)=.72, p<.002.” Positive relationship (optimists had more assists and steals) and negative relationship (optimists had fewer rebounds and more fouls) observed and the observed negative relationships were a function of these female athletes attributing negative outcomes to lack of effort (defensive pessimism) as opposed to lack of ability (depressive pessimism). Optimism and individual mindset of pessimism may need to be understood to clarify the role of positivity in sports.
Psychological Determinants of Whole-Body Endurance Performance
McCormick et al. 2015
Key Points:
This was the first study to systematically review the role fop psychological determinants of endurance performance.
27% of studies were of weak quality while only 4% were strong. Furthermore, concerns with intervention integrity were identified in 9 studies.
While some inconsistencies in results were observed, the authors concluded that psychological skills training could benefit endurance athletes with imagery, positive/motivational self-talk and goal setting, improving endurance performance most consistently
The author notes that the role of multiple psychological skills as opposed to one psychological skill remains unclear.
Mental fatigue was also shown to undermine endurance performance in 1 strong and 2 moderate studies, while verbal encouragement and head-to-head competition can have a positive effect.
Interventions that influenced perception of effort consistently affected endurance performance.
Some athletes may have already adopted psychological skills and may be utilizing them even in control groups.
Methods: 12 separate database searches conducted using keywords relating to endurance performance measurements and physiological factors. Included if in English, peer-reviewed journal, experimental or quasi-experimental research designs used, athletes/healthy adult participants, used psychological manipulation, met definition of endurance, and measured performance. 200m swim, 800m run, 75s max-effort at or above these distances classified as endurance performance. Effect size calculated.
Results: Paper qualities: 2 strong, 13 moderate, 12 weak, 1 non-applicable. Concerns with intervention integrity identified in 9 studies. 29studies (63 %) conducted in laboratory setting and 17 studies (37 %) conducted in field setting. Studies measured running (n = 23), cycling (n = 14), swimming (n = 4), gymnasium triathlon (n = 2), rowing (n = 2) and walking (n = 1) performance, using time trials (alone or in a group, n = 25), incremental tests (n = 10), constant workload tests (n = 6), constant duration tests (n = 4) and points won in competition (n = 1). Goal setting improve endurance performance in 2 studies with amount of improvement showing correlation to both ego and task orientation in a group of high school runners and goal-setting improving cycling time during increment test in non-athletes. Consistent support was found for using imagery, self-talk and goal setting to improve endurance performance. 4 of 5 studies showed that self-talk interventions improved performance (3 moderate-quality, 2 weak-quality studies) through reduced perceived effort. Observed in 3 cycling studies and a swimming study but not observed in 30 minutes running study. No studies examined moderating variables (e.g., skill level, personality) or collected social validity data.
A winning smile? Smile intensity, physical dominance, and fighter performance.
Kraus & Chen 2013
Key Points:
I did not have full access to this paper
The sign of physical dominance associated with a smile was discussed in this article to explain its role in fighting performance.
The authors note that prior studies suggest that before physical confrontation, smiles are a nonverbal sign of reduced hostility and aggression that unintentionally communicates reduced physical dominance to competitors.
2 studies are mentioned:
“Study 1 found that professional fighters who smiled more in a prefight photograph taken facing their opponent performed more poorly during the fight in relation to their less intensely smiling counterparts.
In Study 2, untrained observers judged a fighter as less hostile and aggressive, and thereby less physically dominant when the fighters' facial expression was manipulated to show a smiling expression in relation to the same fighter displaying a neutral expression.”
The topic of this paper suggests that positivity in the form of smiles may not be beneficial to athletic performance if the sport requires participants to exude dominance and strength in the form of hostility and aggression.
To draw more reliable conclusions on the role of positivity of athletic performance, it may be important to examine the effect of positive disposition on individual sports or to examine positivity through a different angle than smiles.
Positivity in healthcare: relation of optimism to performance
Luthans et al. 2008
Key Points:
I did not have full access to this paper
This study of 78 nurses in the Midwest examined the relationship between the optimism of nurses and their performance in the healthcare setting and reported that optimism was significantly associated with improved performance evaluations from supervisors.
It is important to note that this was an exploratory study with a limited sample size and data set.
The study implies that optimism may positively impact performance. However, it is a reach to say that the findings from this study would translate directly to the athletic context, as the method of assessing performance may be considered subjective.
Methods: 78 nurses in hospitals. Participants completed surveys to measure their state of optimism.
Supervisors' performance evaluations data assessed. Spearman correlations and ANOVA were used for analysis.
Results: The study reports a highly significant positive relationship between the nurses' measured optimism and their supervisors' ratings of their commitment to the hospital’s mission. The evaluations measured their contribution to increasing the customers’ satisfaction, and an overall measure of work performance.
The bright side of sports: a systematic review on well-being, positive emotions and performance
Peris-Delcampo et al. 2024
Key Points:
The detrimental role of negative emotions, such as anxiety, stress, sadness, or anger, on sports performance has been the focus of studies in recent decades, however studies assessing positive emotions are increasing.
This paper is a systematic review of well-being and pleasant emotions on sports performance.
Findings suggest that intrinsic motivation and personal satisfaction are the best and most effective way to enhance performance. The authors present the bright side of sports as a complement or mediator of the negative variables that influence performance.
Mental toughness and psychological well-being are derived from positive coping strategies, optimism, perfectionism, and self-compassion.
Methods: Papers published on databases between 2000 and 2023 included. Self-realisation, performance, and health was searched in relation to words associated with positive psychology. 238 papers obtained directly. 109 papers excluded for errors/duplicates. 51 papers selected for review. Papers excluded if age outside 2-65 range, qualitative methodologies, COVID-related, not sports-related, journals not of psychology. N=11 papers included in final sample.
Results: Great data dispersion across the 11 papers due to variations in methodologies. When positive variables were obtained, some negative variables, like anxiety, stress, and irrational thoughts, were affecting the positive. Among positive psychological factors, coping strategies, optimism, perfectionism, and self-compassion are deemed especially important. Traits like mental toughness and psychological well-being also matter, but they are more complex as they are built from those other traits.
Positive elements, such as resilience, or the learning of coping strategies, are directly generated by the education and culture in which the athlete is immersed.
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