Eli Puterman

Long-term physical activity and exercise have been shown to mitigate neurobiological responses to acute psychosocial stressors. There is also evidence that engaging in a single bout of exercise has immediate effects on reducing neurobiological reactivity to acute psychosocial stressors. However, much of this previous work applied definitions of intensity zones on American College of Sports Medicine’s global prescription recommendations, not based on individualized, physiologically meaningful cut-off points for demarcating the intensities at which participants exercised. This project expands on prior evidence by investigating the extent to which a single bout of exercise, performed at light, moderate, or vigorous intensities – established with meaningful indicators of changes in metabolic needs – alters the neurobiological response to a subsequently induced psychosocial stressor. It is hypothesized that vigorous intensity, defined as the midway point between the first and second ventilatory thresholds, will dampen cortisol output following a subsequently induced psychological stressor, compared to moderate (defined as being 10% below the VT1) and light (set at 1.7km/hour) intensities. Moderate intensity is expected to dampen the cortisol trajectory as compared to the light intensity, but to a lesser extent than vigorous. To achieve this, participants complete a modified maximal cardiopulmonary exercise test (CPET) to determine their individual ventilatory thresholds. Participants then return to the lab a second time to complete the experiment, whereby they are randomized to complete a 30-minute exercise at their randomized intensity zone, followed by the Trier Social Stress Test 45 minutes later. Multilevel Growth Curve Analysis determined that participants in the vigorous group had significantly slower rates of increased cortisol compared to both the light and moderate groups. Results also indicated no significant differences in cortisol trajectories between the light and moderate groups, apart from the fact that those in the moderate group had lower estimated starting points prior to starting the TSST. Results suggest that the current findings may be a result of the negative feedback loop, if they hold when the complete sample is analyzed. Examination of other psychological and physiological responses to psychosocial stressors will help elucidate the extent to which exercise mitigates stress reactivity in its more comprehensive conceptualization.

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Depressive symptoms in midlife and older adulthood are common, persistent, and associatedwith cardiovascular diseases, cognitive impairment, and earlier mortality. Previous research hasidentified risk factors for depressive symptoms in middle and older adulthood, such as increasingage, female sex, race and ethnicity, major life stressors, lack of social connectedness,neuroticism, lower life satisfaction, physical inactivity, alcohol use, and polygenic risk scores, toname a few. However, these multi-factorial predictors have not been included in the same studyto determine their relative contribution to depressive symptoms in middle and older adulthood.Furthermore, previous research has only assessed depressive symptoms and their predictorscross-sectionally or prospectively (i.e., 2 time points), which misconstrues the dynamic temporalnature of depressive symptoms. Therefore, using data from the Health and Retirement Study (N= 13,994), the aims of this study were threefold: 1) estimate trajectories of depressive symptomsin middle-aged and older adults using growth mixture modelling (GMM), 2) identify predictorsof trajectory groups in order of importance using random forest (RF) analysis, and 3) comparehow trajectory groups differ in relation to the most important predictors using multinomiallogistic regression (MLR). GMM indicated that there were five latent classes following distincttrajectories of depressive symptoms over 10 years: “consistently low”, “increasing”,“consistently moderate”, “decreasing”, and “consistently high”. Out of a total of 72 predictorsranging from demographic to genetic factors, the top five predictors of depressive symptomstrajectories were trait anxiety, lower life satisfaction, neuroticism, perceived constraints, andhopelessness. MLR demonstrated that trajectory groups differed significantly in relation topsychological, health, and social factors, which highlights potential avenues for intervention.

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Background. Current research on employee well-being largely entails focus on physical andmental health and illness, as well as functioning specific to the workplace. Yet, more recent conceptualizations of well-being extend beyond the presence or absence of health or illness to concepts of thriving or languishing, measured using an outcome-wide measurement approach. Accordingly, healthcare worker (HCW) multidimensional well-being as an overarching concept should be inclusive of a broad range of ill-being and well-being indictors that span multiple dimensions, including physical, psychological, and psychosocial realms of life. A recent 12- week mHealth exercise intervention for HCWs in Vancouver, BC demonstrated significant treatment effects for depressive symptoms, burnout symptoms, and absenteeism among those randomized to an exercise versus waitlist control condition. Secondary analyses were conducted to examine whether positive treatment effects could extend to a broader range of multidimensional ill-being and well-being outcomes.Methods. Data was from the COVID-19 Pandemic and Exercise for Healthcare Workers (COPE HCW) trial, a two-arm parallel randomized controlled trial for low-active HCWs working at Providence Health Care centers across Vancouver, BC. The effects of engagement with a suite of exercise applications for 80 minutes per week for 12 weeks (vs. waitlist control) on indicators of multidimensional ill-being and well-being were examined. Treatment effects for physical health symptoms, recent global stress, work-to-personal life interference, overall physical health, overall mental/emotional health, life satisfaction, psychological flourishing, resilience, and work- to-personal life enhancement were analyzed using intent-to-treat analyses with a structural equation modelling (SEM) growth model approach.Results. By the end of the trial, significant treatment effects were observed for all outcomes, such that those in the exercise condition (vs. waitlist control) reported significant reductions in ill-being and improvements in well-being measures. Adherence to the intervention decreased over time, and treatment effects were most apparent for those who engaged with the exercise apps the most.Conclusions. mHealth exercise is one individual-level behavioral intervention which was successful in improving multidimensional ill-being and well-being among HCWs. Findings will help inform future employee wellness programming by providing evidence that mHealth exercise can be used as a modality to support well-being across different life domains.

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The role of the gut microbiome in host physiology and its association with various diseases is a developing field of research and information on the impact of physical activity on the gut microbiome is limited, particularly in diverse population-based cohorts. This study examines the associations between physical activity with gut microbial diversity, composition, and function. Utilizing data from the Coronary Artery Risk Development in Young Adults (CARDIA) study, we evaluated the relationship between physical activity and the gut microbiome in participants aged 47-61. Physical activity was assessed through self-reported measures (n = 581) and accelerometer data (n= 364), while gut microbiome measures were analyzed using whole genome shotgun (WGS) sequencing. We employed regression models for cross-sectional analyses, adjusting for sociodemographic and behavioural covariates, such as diet, as well as body mass index (BMI). Self-reported physical activity showed significant positive associations with beta diversity and negative associations with species richness, a measure of alpha diversity, after adjusting for all factors, but no change in Shannon Diversity Index. Identification of associations with specific bacterial species, metabolic pathways and enzyme families revealed both positive and negative associations with self-reported physical activity levels, highlighting complex associations between physical activity and gut microbiota. Accelerometer data revealed significant positive associations between beta diversity and moderate-to-vigorous intensity physical activity (MVPA), with no associations with alpha diversity or specific species, metabolic pathways, and enzyme families. The study underscores the intricate association between physical activity and the gut microbiome in a middle-aged, racially diverse cohort. Our findings support the notion that regular physical activity is associated with changes in the gut microbiome, which promote improved host health, and negatively associated with metabolic functions that have been implicated in pathological states. The study's diverse demographic and robust methodology strengthen its external validity and contribute to a growing body of evidence on lifestyle factors that are associated with the gut microbiome. While these insights enhance our understanding of the multifactorial nature of gut microbiome dynamics, future studies should employ longitudinal and interventional designs with integrated methodologies for physical activity assessment, using the most up-to-date methods of DNA analysis.

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The primary purpose of this pilot study was to examine the complex interplay between training loads, stress, recovery, menstrual patterns, and performance in female varsity swimmers. This study included 13 female varsity swimmers monitored over two seasons from the University of British Columbia Varsity Swim Team. Data collected included: external load (training volume), internal load (perceived exertion), stress, recovery, menstrual patterns and performance. We aimed to deepen our current understanding of these relationships using continuous-time modeling (CTM). As a novel analytical approach in sports-science research, CTM offers a unique method to evaluate variables change relative to reach other over time. We selected this analytical approach as traditional analytic approaches struggle to capture the nuanced effects of training on performance over time as they unfold, particularly in small populations. Our results showed a significant amount of heterogeneity within the study population. This highlights the importance of an individualized approach to training, recovery, and performance. Additionally, we found increases in external load resulted in a decrease in the rate of change in reported stress metrics. This suggests there may be a delay in the body’s ability to adapt when external load is increased. Unexplained variability was noted in several metrics, including internal load, performance, and recovery, pointing to the influence of additional, factors which were not included in our models. These factors may include sleep quality and/or energy availability status. In conclusion, this study highlights the potential of CTM in sports science research and underscores the importance of an individualized approach to training and recovery. Overall, this study contributes to a deeper understanding of the multi-faceted and dynamic nature of female athletes' health and performance and advocates for tailored interventions to optimize training outcomes and support athlete well-being.

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Physical activity and exposure to nature have each been recognized for their positive effects on health and wellbeing. When taken in tandem, outdoor exercise is proposed to have additive benefits compared to exercising indoors or being inactive outdoors. Previous reviews of green exercise have reported inconclusive findings due to a paucity of high-quality evidence. The present review sought to summarize the body of literature that compares physiological and perceptual differences of a single bout of exercise in outdoor spaces versus indoor spaces.Following the PRISMA reporting guidelines for systematic reviews, a search was conducted in nine databases for any articles published before November 2019. When studies and outcomes were methodologically uniform, quantitative analyses was completed. Vote counting and harvest plots were used to synthesize the remaining outcomes. Quality of articles was assessed using the Cochrane Risk of Bias Assessment Tool.The findings of 24 articles (Total N = 757) were examined. Summarized outcomes include objective exercise intensity, perceived exertion, performance, neuroendocrine responses, cardiovascular responses, thermoregulation, enjoyment, intention for future exercise and perceptions of the environment. Meta-analysis was conducted for mean heart rate, perceived exertion, mean speed, time to completion, enjoyment, and future intention for exercise. Significant effects of the environment were detected for meta-analyses of perceived exertion (g = -0.84, 95% CI = [-1.60, -0.09], p = 0.03) and enjoyment (g = 1.24, 95% CI = [0.59, 1.89], p 0.001). Methodological diversity made it impossible to statistically summarize the remaining outcomes, results split between no effect and statistically significant changes, resulting in inconclusive findings. The majority of included studies (54%) were assessed to have a high risk of bias and all other studies (46%) were assessed to have some concerns of risk of bias.Although no additive physiological benefits were identified as a result of exercising outdoors, exercise still presents well-documented potential for improved health. At equivalent objective intensity, outdoor exercise appears to feel easier and more enjoyable than indoor exercise. Outdoor exercise may be more likely to be repeated and more sustainable, allowing physiological benefits to accrue over repeated bouts.

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While the body’s stress system plays an adaptive role in helping humans respond to challenging and threatening stimuli, frequent or prolonged exposure to difficult stressors can detriment both physical and psychological health, and lead to the eventual development of chronic diseases. Though chronic activation of the stress system damages health, physical activity can mitigate the psychological and physiological stress response in daily life, benefiting long term health. While research has examined the effects of fitness level and frequent physical activity on various features of the human stress response, little is known regarding the effect of a single bout of aerobic activity on the physiological reactivity to an acute stressor (i.e. the increasing response over time), and the recovery, or return, back to baseline. The current study thus investigated two research questions: (1) whether the effects of exercise on the Hypothalamic Pituitary Adrenal (HPA) axis response (i.e. reactivity and recovery) to an acute stressor depends on the intensity at which a bout of exercise is performed, and (2) whether associations exist between the HPA-axis outcomes of exercising at various intensities and the cortisol responses to a subsequent psychosocial stressor, delineating a biological mechanism of the stress-buffering effects of exercise. These questions were addressed by constructing mixed-effects models, with between person and within person effects, in which eighty-three 18- to 30-year-old men were randomized to exercise at either 30%, 50% or 70% of their heart rate reserve and then underwent a psychosocial stress task. ANCOVA and Multilevel Growth Curve Analysis determined that more intense exercise elicited dampened cortisol responses to the stress task, marked by lower total cortisol levels, diminished cortisol reactivity and faster recovery to baseline values, as compared to less intense exercise. Moreover, exercise itself elicited a cortisol response proportional to the intensity at which it was performed, and this exercise-associated HPA-axis response was inversely proportional to the cortisol response to the subsequent stress task. This study concluded that exercise-intensity dampens the HPA-axis stress response in a dose dependent manner with mounting evidence that the cortisol released from exercising intensely helps to suppress the subsequent cortisol response to a stressor.

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Background: Nearly one-quarter of Canadians report high levels of daily stress. This is alarming as chronic stress has been associated with several co-morbidities and premature mortality. In order to create beneficial interventions and public policy, factors associated with stress must be identified. While a wealth of research has determined a myriad of correlates of stress, the majority of this work has used approaches that focus on a very limited number of correlates per study, often from within one field of study. Currently there are no studies that analyze large-scale data sets and test multiple variables simultaneously.Methods: This study analyzed data from the 2012 Canadian Community Health Survey - Mental Health, including 67 factors from a range of disciplines and over 23,000 participants. This study uses two approaches to test the associations between these factors and chronic stress including traditional statistics (i.e., simple linear regression and multiple linear regression) and machine learning algorithms (i.e., random forest analysis). Results: The simple linear regression analysis showed that negative social interaction, life satisfaction, and higher levels of insomnia have the largest effect size in their association with chronic stress. Random forest analyses found that, after accounting for variance from other factors and considering complex interactions, life satisfaction, negative social interactions, and age were the most important correlates of chronic stress.Conclusion: This study highlights that the important correlates of stress do not come from one field, but rather are a combination of psychological, social, and demographic factors. These novel findings highlight potential target pathways for devising new stress reduction interventions. However, as this study was exploratory and correlational, more research is needed regarding direction of effect and potential confounding variables.

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The potential mechanisms driving the optimal, healthy physical and psychological development of children have been studied extensively (Janssen et al., 2010; Milteer, Ginsburg, & Mulligan, 2012; Parfitt & Eston, 2005). Specific movement behaviours, including physical activity, sedentary time, and sleep have been studied independently to examine their influence on health outcomes. Emotional well-being, which encompasses a variety of psychological concepts including optimism, general self-concept, satisfaction with life, and sadness, is considered an important element in the healthy development of children (Guerra & Bradshaw, 2008). This study examined the extent to which four objectively-measured movement behaviours – light physical activity (LPA), moderate to vigorous physical activity (MVPA), sedentary time, and sleep – are associated with emotional well-being in a sample of grades four and five children (N = 21). This study had three objectives: 1) to examine independent associations between the four separate movement behaviours and emotional well-being, 2) to examine the relationship between one movement behaviour and emotional well-being relative to time spent in other movement behaviours using compositional analysis, and 3) to examine whether time spent in sedentary screen activities versus non-screen sedentary activities moderated the relationship between objectively-measured sedentary time and emotional well-being. For objective 1, among the independent Spearman correlations, only MVPA was significantly and positively correlated with emotional well-being (ρ = 0.77, p 0.001). Using compositional analysis for objective 2, no significant relationships were found between any one of the four movement behaviours and emotional well-being relative to time spent in other movement behaviours. Finally, for objective 3, no significant moderating effects were found for time spent in sedentary screen time versus non-screen sedentary time on the relationship between objectively-measured sedentary time and emotional well-being. This study concluded that objectively-measured MVPA was significantly and positively associated with emotional well-being in the sample; however, future studies with a larger sample size are recommended, as these findings were limited by a small sample size.

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