The effects of acute exercise on stress reactivity assessed via a multidimensional approach: a systematic review.

Psychological stress is associated with numerous deleterious health effects. Accumulating evidence suggests acute exercise reduces stress reactivity. As stressors activate a wide array of psychological and physiological systems it is imperative stress responses are examined through a multidimensional lens. Moreover, it seems prudent to consider whether stress responses are influenced by exercise intervention characteristics such as modality, duration, intensity, timing, as well as participant fitness/physical activity levels. The current review therefore examined the role of acute exercise on stress reactivity through a multidimensional approach, as well as whether exercise intervention characteristics and participant fitness/physical activity levels may moderate these effects. Stress reactivity was assessed via heart rate, blood pressure, cortisol, catecholamines, and self-report. A systematic search following PRISMA guidelines of five databases was updated in November 2022. Reviewed studies met the following criteria: English language, participants aged ≥ 18, use of acute exercise, use of a validated stress-inducing task, and assessment(s) of stress reactivity. Thirty-one studies (1386 participants) were included. Acute exercise resulted in reliable reductions to blood pressure and cortisol. Acute exercise yielded mostly negligible effects on heart rate reactivity and negligible effects on self-report measures. As for exercise intervention characteristics, intensity-dependent effects were present, such that higher intensities yielded larger reductions to reactivity measures, while limited evidence was present for duration, modality, and timing-dependent effects. Regarding participant fitness/physical activity levels, the effects on stress reactivity were mixed. Future work should standardize the definitions and assessment time points of stress reactivity, as well as investigate the interaction between physiological and psychological stress responses in real-world contexts.

Increased iron in the substantia nigra pars compacta identifies patients with early Parkinson'sdisease: A 3T and 7T MRI study.

Degeneration in the substantia nigra (SN) pars compacta (SNc) underlies motor symptoms in Parkinson's disease (PD). Currently, there are no neuroimaging biomarkers that are sufficiently sensitive, specific, reproducible, and accessible for routine diagnosis or staging of PD. Although iron is essential for cellular processes, it also mediates neurodegeneration. MRI can localize and quantify brain iron using magnetic susceptibility, which could potentially provide biomarkers of PD. We measured iron in the SNc, SN pars reticulata (SNr), total SN, and ventral tegmental area (VTA), using quantitative susceptibility mapping (QSM) and R2* relaxometry, in PD patients and age-matched healthy controls (HCs). PD patients, diagnosed within five years of participation and HCs were scanned at 3T (22 PD and 23 HCs) and 7T (17 PD and 21 HCs) MRI. Midbrain nuclei were segmented using a probabilistic subcortical atlas. QSM and R2* values were measured in midbrain subregions. For each measure, groups were contrasted, with Age and Sex as covariates, and receiver operating characteristic (ROC) curve analyses were performed with repeated k-fold cross-validation to test the potential of our measures to classify PD patients and HCs. Statistical differences of area under the curves (AUCs) were compared using the Hanley-MacNeil method (QSM versus R2*; 3T versus 7T MRI). PD patients had higher QSM values in the SNc at both 3T (padj = 0.001) and 7T (padj = 0.01), but not in SNr, total SN, or VTA, at either field strength. No significant group differences were revealed using R2* in any midbrain region at 3T, though increased R2* values in SNc at 7T MRI were marginally significant in PDs compared to HCs (padj = 0.052). ROC curve analyses showed that SNc iron measured with QSM, distinguished early PD patients from HCs at the single-subject level with good diagnostic accuracy, using 3T (mean AUC = 0.83, 95 % CI = 0.82-0.84) and 7T (mean AUC = 0.80, 95 % CI = 0.79-0.81) MRI. Mean AUCs reported here are from averages of tests in the hold-out fold of cross-validated samples. The Hanley-MacNeil method demonstrated that QSM outperforms R2* in discriminating PD patients from HCs at 3T, but not 7T. There were no significant differences between 3T and 7T in diagnostic accuracy of QSM values in SNc. This study highlights the importance of segmenting midbrain subregions, performed here using a standardized atlas, and demonstrates high accuracy of SNc iron measured with QSM at 3T MRI in identifying early PD patients. QSM measures of SNc show potential for inclusion in neuroimaging diagnostic biomarkers of early PD. An MRI diagnostic biomarker of PD would represent a significant clinical advance.

Acute stress negatively impacts on-task behavior and lecture comprehension.

Acute stress has been shown to disrupt cognitive and learning processes. The present study examined the effects of acute stress on mind wandering during a lecture and subsequent lecture comprehension in young adults. Forty participants were randomized to acute stress induction via the Trier Social Stress Test or rest prior to watching a twenty-minute video lecture with embedded mind wandering probes, followed by a lecture comprehension assessment. Stress responses were assessed via heart rate, blood pressure, salivary cortisol, and state anxiety. Individuals exposed to acute stress endorsed greater mind wandering at the first checkpoint and lower lecture comprehension scores. Moreover, state anxiety post stress was positively associated with mind wandering at the first and second checkpoint and negatively associated with lecture comprehension. Only mind wandering at the third checkpoint was negatively correlated with overall lecture comprehension. Taken together, these data suggest that acute stress, mind wandering, and lecture comprehension are inextricably linked.

Acute stress imparts a transient benefit to task-switching that is not modulated following a single bout of exercise.

Introduction: Cognitive flexibility represents a core component of executive function that promotes the ability to efficiently alternate-or "switch"-between different tasks. Literature suggests that acute stress negatively impacts cognitive flexibility, whereas a single bout of aerobic exercise supports a postexercise improvement in cognitive flexibility. Here, we examined whether a single bout of aerobic exercise attenuates a stress-induced decrement in task-switching. Materials and Methods: Forty participants (age range = 19-30) completed the Trier Social Stress Test (TSST) and were randomized into separate Exercise or Rest groups entailing 20-min sessions of heavy intensity exercise (80% of heart rate maximum via cycle ergometer) or rest, respectively. Stress induction was confirmed via state anxiety and heart rate. Task-switching was assessed prior to the TSST (i.e., pre-TSST), following the TSST (i.e., post-TSST), and following Exercise and Rest interventions (i.e., post-intervention) via pro- (i.e., saccade to veridical target location) and antisaccades (i.e., saccade mirror-symmetrical to target location) arranged in an AABB task-switching paradigm. The underlying principle of the AABB paradigm suggests that when prosaccades are preceded by antisaccades (i.e., task-switch trials), the reaction times are longer compared to their task-repeat counterparts (i.e., unidirectional prosaccade switch-cost). Results: As expected, the pre-TSST assessment yielded a prosaccade switch cost. Notably, post-TSST physiological measures indicated a reliable stress response and at this assessment a null prosaccade switch-cost was observed. In turn, post-intervention assessments revealed a switch-cost independent of Exercise and Rest groups. Conclusion: Accordingly, the immediate effects of acute stress supported improved task-switching in young adults; however, these benefits were not modulated by a single bout of aerobic exercise.

Binge drinking and smoking are associated with worse academic performance in Canadian undergraduate students.

OBJECTIVE: Test the hypothesis that smoking, fast-food consumption, and binge drinking were negatively associated with academic performance in Canadian undergraduate students. PARTICIPANTS: Undergraduate students across Canada [n = 411 (335♀) aged: 22 ± 4 years] completed a questionnaire regarding their lifestyle behaviors and academic grades. METHODS: Relationships between lifestyle behaviors and academic performance were assessed via covariate-adjusted multiple regressions. Mediation models were used to test whether significant relationships between smoking/fast-food and grades were explained by binge drinking. RESULTS: Smoking (ß= -4.00, p < .001) and binge drinking (ß= -1.98, p = .002) were independent predictors of grades (average: 84 ± 8%). Binge drinking partially mediated the relationships between smoking (indirect effect ß= -1.19, 95%CI [-2.49, -0.08] and fast-food consumption (indirect effect: ß= -.75, 95%CI [-1.20, -0.29]), with grades. CONCLUSIONS: These findings highlight the negative influence of binge drinking, smoking, and fast-food consumption on academic success, with binge drinking as a partial mediator of these relationships.

A single bout of passive exercise mitigates a mental fatigue-induced inhibitory control deficit.

Sustained cognitive effort associated with the psychomotor vigilance task (PVT) increases objective and subjective measures of mental fatigue and elicits a post-PVT inhibitory control deficit. In contrast, passive exercise wherein an individual's limbs are moved via an external force (i.e., mechanically driven cycle ergometer flywheel) provides a postexercise inhibitory control benefit linked to an exercise-based increase in cerebral blood flow. Here, we examined whether passive exercise performed concurrently with the PVT 'blunts' an inhibitory control deficit. On separate days, participants (N = 27) completed a 20 min PVT protocol (control condition) and same duration PVT protocol paired with passive cycle ergometry (passive exercise condition). Prior to (i.e., baseline), immediately after and 30 min after each condition inhibitory control was assessed via the antisaccade task. Antisaccades require a goal-directed eye movement (i.e., saccade) mirror-symmetrical to a target and provide an ideal tool for evaluating task-based changes in inhibitory control. PVT results showed that vigilance (as assessed via reaction time: RT) during control and passive exercise conditions decreased from the first to last 5 min of the protocol and increased subjective ratings of mental fatigue. As well, in the control condition, immediate (but not 30-min) post-intervention antisaccade RTs were longer than their baseline counterparts-a result evincing a transient mental fatigue-based inhibitory control deficit. For the passive exercise condition, immediate and 30-min post-intervention antisaccade RTs were shorter than their baseline counterparts and this result was linked to decreased subjective ratings of mental fatigue. Thus, passive exercise ameliorated the selective inhibitory control deficit associated with PVT-induced mental fatigue and thus provides a potential framework to reduce executive dysfunction in vigilance-demanding occupations.

Lessons from zoom-university: Post-secondary student consequences and coping during the COVID-19 pandemic-A focus group study.

The COVID-19 pandemic dramatically altered the model of university education. However, the most salient challenges associated with online learning, how university students are coping with these challenges, and the impact these changes have had on students' communities of learning remain relatively unexplored. Changes to the learning environment have also disrupted existing communities of learning for both lower and upper-year students. Hence, the purpose of our study was to explore how: (1) academic and personal/interpersonal challenges as a result of COVID-19; (2) formal and informal strategies used to cope with these academic and non-academic challenges; (3) and services or resources provided by the institution, if any, affected students' communities of learning. Six focus groups of 5-6 students were conducted, with two focus groups specifically dedicated to upper and lower year students. Questions related to academic and interpersonal challenges, formal and informal coping strategies, and access to/use of university services/resources were posed. Common challenges included poor accommodation from professors and administrators; burnout from little separation school and personal life; lack of support for students transitioning out of university; and difficulties forming and maintaining social networks. These findings suggest the importance of fostering communities of learning informally and formally at universities beyond the pandemic context.

Exercise behaviors and resource use among graduate students at a Canadian university: A cross-sectional study.

OBJECTIVE: Participation in regular exercise among post-secondary students is often low. Our cross-sectional study aimed to assess exercise levels, perceived barriers/motivators to exercise, and knowledge and use of exercise resources in graduate students. PARTICIPANTS: We recruited graduate students across various disciplines at a large Canadian university. METHODS: Participants (n = 540) completed an anonymous mixed methods online survey. RESULTS: Approximately 11% of participants reported not participating in any form of weekly exercise, and only 9.4% met the Canadian Physical Activity Guidelines. The most common barrier and motivator to exercise was time commitment and improving physical health, respectively. Some participants were aware of available exercise services but most did not use them. Suggestions for improving services included having graduate-dedicated exercise space and resources. CONCLUSIONS: Low exercise participation among graduate students may be due to a lack of education of available resources or a lack of existing resources that meet their specific needs.

Tobacco use among varsity athletes - why do they do it and how do we make it stop: a brief report.

The current study explores the motivations underlying tobacco use among varsity athletes. A cross-sectional exploratory mixed method approach was used. Both tobacco users (TU) and non-tobacco users (NTU) completed an online survey of closed and open-ended questions. These questions focused on tobacco use, motivations for tobacco use, teammate and coaches' perceptions of athlete tobacco use, and self-perceived effects of tobacco use on health and athletic performance. Thirty-eight completed surveys were included of which 12 were TU and 26 were NTU. The majority of TU indicated that they used products during the off-season. Motivations for using tobacco products included social influences, stress-relief, and increasing energy. TU mostly indicated that there are negative effects on their health but not on their athletic performance, whereas NTU reported potential detrimental effects on their teammate's performance. Overall, varsity athletes who use tobacco products are aware of the health effects and negative opinions of their teammates.

Total Sedentary Time and Cognitive Function in Middle-Aged and Older Adults: A Systematic Review and Meta-analysis.

BACKGROUND: An estimated 47 million people have dementia globally, and around 10 million new cases are diagnosed each year. Many lifestyle factors have been linked to cognitive impairment; one emerging modifiable lifestyle factor is sedentary time. OBJECTIVE: To conduct a systematic review and meta-analysis of peer-reviewed literature examining the association between total sedentary time with cognitive function in middle-aged and older adults under the moderating conditions of (a) type of sedentary time measurement; (b) the cognitive domain being assessed; (c) looking at sedentary time using categorical variables (i.e., high versus low sedentary time); and (d) the pattern of sedentary time accumulation (e.g., longer versus shorter bouts). We also aimed to examine the prevalence of sedentary time in healthy versus cognitively impaired populations and to explore how experimental studies reducing or breaking up sedentary time affect cognitive function. Lastly, we aimed to conduct a quantitative pooled analysis of all individual studies through meta-analysis procedures to derive conclusions about these relationships. METHODS: Eight electronic databases (EMBASE; Web of Science; PsycINFO; CINAHL; SciELO; SPORTDiscus; PubMed; and Scopus) were searched from inception to February 2021. Our search included terms related to the exposure (i.e., sedentary time), the population (i.e., middle-aged and older adults), and the outcome of interest (i.e., cognitive function). PICOS framework used middle-aged and older adults where there was an intervention or exposure of any sedentary time compared to any or no comparison, where cognitive function and/or cognitive impairment was measured, and all types of quantitative, empirical, observational data published in any year were included that were published in English. Risk of bias was assessed using QualSyst. RESULTS: Fifty-three studies including 83,137 participants met the inclusion criteria of which 23 studies had appropriate data for inclusion in the main meta-analysis. The overall meta-analysis suggested that total sedentary time has no association with cognitive function (r = -0.012 [95% CI - 0.035, 0.011], p = 0.296) with marked heterogeneity (I2 = 89%). Subgroup analyses demonstrated a significant negative association for studies using a device to capture sedentary time r = -0.035 [95% CI - 0.063, - 0.008], p = 0.012). Specifically, the domains of global cognitive function (r = -0.061 [95% CI - 0.100, - 0.022], p = 0.002) and processing speed (r = -0.067, [95% CI - 0.103, - 0.030], p < 0.001). A significant positive association was found for studies using self-report (r = 0.037 [95% CI - 0.019, 0.054], p < 0.001). Specifically, the domain of processing speed showed a significant positive association (r = 0.057 [95% CI 0.045, 0.069], p < 0.001). For prevalence, populations diagnosed with cognitive impairment spent significantly more time sedentary compared to populations with no known cognitive impairments (standard difference in mean = -0.219 [95% CI - 0.310, - 0.128], p < 0.001). CONCLUSIONS: The association of total sedentary time with cognitive function is weak and varies based on measurement of sedentary time and domain being assessed. Future research is needed to better categorize domains of sedentary behaviour with both a validated self-report and device-based measure in order to improve the strength of this relationship. PROSPERO registration number: CRD42018082384.

The Influence of Motivators and Barriers to Exercise on Attaining Physical Activity and Sedentary Time Guidelines among Canadian Undergraduate Students.

Canadian 24 h movement guidelines recommend engaging in >150 min/week of moderate-vigorous-intensity physical activity and ≤8 h/day of sedentary time. Half of Canadian post-secondary students do not meet physical activity or sedentary time guidelines. This pan-Canadian study aimed to (1) identify commonly cited motivators/barriers to exercise, and (2) determine which motivators/barriers were most influential for attaining physical and sedentary activity guidelines. A total of 341 respondents (279 females, 23 ± 4 years old, 53% met activity guidelines, 49% met sedentary guidelines) completed an online survey regarding undergraduate student lifestyle behaviours. Improved physical health (74% of respondents), mental health (67%), physical appearance (60%), and athletic performance (28%) were the most common motivators to exercise. The most common barriers were school obligations (68%), time commitments (58%), job obligations (32%), and lack of available fitness classes (26%). Students citing improved athletic performance (odds ratio (OR) = 1.94, p = 0.02) were more likely to adhere to activity guidelines, while those who selected physical health (OR = 0.56, p = 0.03) and physical appearance (OR = 0.46, p = 0.001) as motivators were less likely to meet activity guidelines. Students who cited school obligations as a barrier were less likely (OR = 0.59, p = 0.03) to meet sedentary guidelines. The motivators and barriers identified provide a foundation for university-led initiatives aimed at promoting physical activity and reducing sedentary time among undergraduate students. Strategies that positively re-frame students' physical health and appearance-based motivations for exercise may be particularly useful in helping more students achieve national activity recommendations.

Describing the use of behavior change techniques among the most popular home workout channels on YouTube: A quantitative content analysis.

The purpose of our study was to describe characteristics of behavior change techniques (BCTs) employed by popular YouTube fitness channels and examine relationships between BCTs used and engagement metrics (e.g. views, likes, comments). Seventy-five videos were coded according to BCT Taxonomy v1. Multi-level modeling was conducted between BCTs and engagement metrics. Fifty-four unique BCTs were used, with "Demonstration of behavior" and "Instruction on how to perform the behavior" used the most. The number of BCTs employed was 12.5 ± 6.65 and BCTs were all unrelated to engagement metrics (ps > 0.05). Application of BCTs within YouTube varies from traditional exercise interventions.

Effects of Caffeine and Acute Aerobic Exercise on Working Memory and Caffeine Withdrawal.

Studies show that a single bout of exercise confers cognitive benefits. However, many individuals use psychoactive substances such as caffeine to enhance cognitive performance. The effects of acute exercise in comparison to caffeine on cognition remain unknown. Furthermore, caffeine use is associated with withdrawal symptoms upon cessation. Whether acute exercise can reduce withdrawal symptoms also remains unknown. The objectives of this study were to compare the effects of acute moderate intensity aerobic exercise to caffeine on working memory (WM) and caffeine withdrawal symptoms (CWS). In Phase I, non-caffeine (n = 29) and caffeine consumers (n = 30) completed a WM assessment, followed by acute exercise and caffeine. In Phase II, caffeine consumers (n = 25) from Phase I underwent the WM assessment and reported CWS following a 12-hour deprivation period. Acute moderate intensity aerobic exercise and caffeine (1.2 mg/kg) significantly improved WM accuracy and reduced CWS comparably. WM performance was not reduced following caffeine deprivation.