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"Muir, Cameron"
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Enjoyment for High-Intensity Interval Exercise Increases during the First Six Weeks of Training: Implications for Promoting Exercise Adherence in Sedentary Adults
This is the first study to show that enjoyment for high-intensity interval exercise increases with chronic training. Prior acute studies typically report high-intensity interval training (HIT) as being more enjoyable than moderate continuous training (MCT) unless the high-intensity intervals are too strenuous or difficult to complete. It follows that exercise competency may be a critical factor contributing to the enjoyment of HIT, and therefore building competency through chronic training may be one way to increase its enjoyment. To test this, we randomly assigned sedentary young adults to six weeks of HIT or MCT, and tracked changes in their enjoyment for the exercise. Enjoyment for HIT increased with training whereas enjoyment for MCT remained constant and lower. Changes in exercise enjoyment were predicted by increases in workload, suggesting that strength adaptions may be important for promoting exercise enjoyment. The results point to HIT as a promising protocol for promoting exercise enjoyment and adherence in sedentary young adults.
Journal Article
Muscle Up: Male Athletes’ and Non-Athletes’ Psychobiological Responses to, and Recovery From, Body Image Social-Evaluative Threats
Negative body image often occurs as a result of social evaluation of the physique in men. Social self-preservation theory (SSPT) holds that social-evaluative threats (SETs) elicit consistent psychobiological responses (i.e., salivary cortisol and shame) to protect one’s social-esteem, status, and standing. Actual body image SETs have resulted in psychobiological changes consistent with SSPT in men; however, responses in athletes have yet to be examined. These responses may differ as athletes tend to experience fewer body image concerns compared with non-athletes. The purpose of the current study was to examine psychobiological (i.e., body shame and salivary cortisol) responses to an acute laboratory body image SET in 49 male varsity athletes from non-aesthetic sports and 63 male non-athletes from a university community. Participants (age range 18–28 years) were randomized into a high or low body image SET condition, stratified by athlete status; measures of body shame and salivary cortisol were taken across the session (i.e., pre, post, 30-min post, 50-min post-intervention). There were no significant time-by-condition interactions, such that athletes and non-athletes had significant increases in salivary cortisol (F3,321 = 3.34, p = .02), when controlling for baseline values, and state body shame (F2.43,262.57 = 4.58, p = .007) following the high-threat condition only. Consistent with SSPT, body image SETs led to increased state body shame and salivary cortisol, although there were no differences in these responses between non-athletes and athletes.
Journal Article
Cortisol Moderates the Relation Between Physical Peer Victimization and Physical Aggression in Preschoolers Attending High-Quality Child Care: Evidence of Differential Susceptibility Across Informants
We examined whether the moderating role of cortisol in the relation between physical peer victimization and physical aggression was better accounted for by a diathesis–stress model or a differential susceptibility model using a multi-informant approach (direct observations, teacher reports, and parent reports) of 198 preschool-aged children attending high-quality child care. Controlling for the influence of household income, hours per week in child care, and child age, we found that our results supported a differential susceptibility effect for boys but not for girls. This effect was replicated within reporters (observer and parent reports) and across reporters (parent-reported victimization and teacher-rated aggression) but for boys only. At higher levels of peer victimization, lower levels of basal cortisol were associated with higher levels of physical aggression, but, at lower levels of peer victimization, lower levels of basal cortisol were associated with lower levels of physical aggression. Furthermore, at higher levels of peer victimization, higher levels of basal cortisol were associated with lower levels of physical aggression, but, at lower levels of peer victimization, higher levels of basal cortisol were associated with higher levels of physical aggression. These results highlight the complex interplay between the social environment and biobehavioral systems in early childhood and the value of considering a differential susceptibility framework in peer-relations research.
Journal Article
The effect of social group size on feather corticosterone in the co-operatively breeding Smooth-billed Ani (Crotophaga ani): An assay validation and analysis of extreme social living
Living closely with others can provide a myriad of fitness benefits, from shared territory defense to co-operative resource acquisition. Costs of social aggregation are not absent, however, and likely influence optimal and observed groups' sizes in a social species. Here, we explored optimal group size in a joint-nesting cuckoo species (the Smooth-billed Ani, Crotophaga ani) using endocrine markers of stress physiology (corticosterone, or CORT). Smooth-billed Anis exhibit intense reproductive competition that is exacerbated in atypically large groups. We therefore hypothesized that intra-group competition (measured by social group size) mediates the desirability and physiological cost of social group membership in this species. To test this hypothesis, we captured 47 adult Smooth-billed Anis (31 males, 16 females) during the breeding seasons of 2012-2014 in south-western Puerto Rico, and documented social group sizes. Tail feathers were sampled and used to quantify CORT (pg/mg) in enzyme-linked immunosorbent assays (ELISAs) (n = 50). Our analyses show significant differences in feather-CORT of adults between categorical group sizes, with individuals from atypically large social groups (≥ x + 1SD) having highest mean concentrations (33.319 pg/mg), and individuals from atypically small social groups (≤ x - 1SD) having lowest mean concentrations (8.969 pg/mg). Whether reproductive competition or effort is responsible for elevated CORT in atypically large social groups, however, remains unclear. Our results suggest that living in atypically large groups is physiologically expensive and may represent an evolutionarily unstable strategy. To our knowledge, this is the first study to explore a correlation between stress physiology and group size in a joint-nesting species.
Journal Article
Men Respond Too: The Effects of a Social-Evaluative Body Image Threat on Shame and Cortisol in University Men
Framed within social self-preservation theory, the present study investigated men’s psychobiological responses to social-evaluative body image threats. University men (n = 66) were randomly assigned to either a high or low social-evaluative body image threat condition. Participants provided saliva samples (to assess cortisol) and completed measures of state body shame prior to and following their condition, during which anthropometric and strength measures were assessed. Baseline corrected values indicated men in the high social-evaluative body image threat condition had higher body shame and cortisol than men in the low social-evaluative body image threat condition. These findings suggest that social evaluation in the context of situations that threaten body image leads to potentially negative psychobiological responses in college men.
Journal Article
Examining University Men’s Psychobiological and Behavioral Response-Recovery Profile From a Social-Evaluative Body Image Threat
Negative body image, which often results from social-evaluative body image threats, is common in young men and related to many harmful outcomes. Using social self-preservation theory (SSPT), the present study investigated the psychobiological (i.e., shame and cortisol) and behavioral (e.g., submission) response-recovery profile to a social-evaluative body image threat in university men. Participants (N = 69; Mage = 20.80 years, SD = 1.84) were randomly assigned to a high-threat (n = 34) or low-threat condition (n = 35). Men in the high-threat condition reported greater post-threat body shame, had greater post-threat cortisol levels, and exhibited more shame-relevant behaviors than men in the low-threat condition. There were no significant differences between conditions for body shame or cortisol at the final post-threat time point (after resting for 30 min). These findings are consistent with SSPT and suggest that men respond to, and recover from, body image threats relatively efficiently.
Journal Article
FIRE AND FURY AND MY KIDS
EVERY TIME WE drive past the Australian War Memorial, the kids plead, 'Can we go there?' Our six-year-old is fascinated by the hulking decommissioned weaponry. 'Was that a tank? Woah, is that part of a ship?' In the rear-view mirror I see three golden-haired boys in their booster seats craning their necks as we continue to Mt Ainslie.
Magazine Article
