• Kinematics and Muscle Activity of the Upper Extremity While Performing Cleaning Tasks

      Pipher, Zachary; Applied Health Sciences Program
      In Canada, occupations including janitors, caretakers, and building superintendents are the fourth most prevalent occupational group among men in the labour force, while cleaners are the 10th most prevalent occupational group among women (Statistics Canada, 2008). Cleaning tasks, typically labor-intensive, are characterized by a combination of static muscle loads (mainly involving bending and twisting of the back) and repetitive movements of the arms and hands requiring high physical exertion. Tasks such as lifting, mopping, and vacuuming often involve awkward postures with both dynamic and static muscular activities. These types of prolonged static and repetitive muscle activities cause muscle fatigue and may lead to musculoskeletal disorders. Therefore, the purpose of this study was to examine the effects of custodial cleaning tasks on upper extremity muscle activity and to assess changes in kinematics throughout the duration of a shift. Ten custodians employed at Brock University performed six cleaning tasks during two different sessions (pre-shift and post-shift). Kinematics of the upper extremity were collected, and muscle activity was recorded from 8 upper extremity muscles. Our results showed no significant changes in mean joint angles or joint range of motion pre-shift to post-shift. However, significant changes were observed in mean and peak EMG amplitudes as a result of time. Higher muscle activity was observed in the upper trapezius and FDS while lower muscle activity was found in the anterior deltoid, posterior deltoid, and EDC post-shift compared to pre-shift. This suggests that custodians use different muscular strategies to maintain task performance over the duration of a work shift. This may imply they are experiencing fatigue due to insufficient rest. This work acts as a stepping-stone into future investigations of custodial work and the adaptations over time.
    • Left ventricular structure in children with developmental coordination disorder

      Chirico, Daniel; Applied Health Sciences Program (Brock University, 2011-03-08)
      Developmental coordination disorder (p-DCD) is a neuro-developmental disorder featuring impairment in developing motor coordination. This study examined left ventricular mass (LVM) in children with p-DCD (n=63) and controls (n=63). LVM was measured using echocardiography. Body composition was determined using BOD POD and peak oxygen uptake (peak V02) was measured by a progressive exercise test. Height, weight and blood pressure were also measured. LVM was not significantly elevated in p-DCD compared to controls. Peak V02 was lower and SBP, BMI, HR, and BF(%) were significantly higher in p-DCD. They also demonstrated elevated stroke volume (SV), cardiac output (CO), end-diastolic volume, and ventricular diameter in diastole. In regression analyses, p-DCD was a significant predictor of SV and CO after accounting for height, FFM, V02FFM, and sex. These differences in children with p-DCD indicate obesity related changes in the left ventricle and may represent early stages of developing hypertrophy of the left ventricle.
    • A Life without Gluten: Dietary Adherence, Physical Activity and Motives

      Crawford, Amy M; Applied Health Sciences Program
      The purpose of this study was to look at individuals living on a gluten-free diet (GFD), their dietary adherence, PA levels and the reasons why they engage in these lifestyle behaviours consistent with Organismic Integration Theory (Deci & Ryan, 2002). Participants (N = 202; Mage = 42.35 years, SDage = 12.43 years) completed a series of online questionnaires. GFD adherence (74.7%) across the previous week was consistent with existing literature (Dowd et al., 2013), but participant physical activity scores were higher than reported normative values (p = .00; Wilson et al., 2010). Specific motives predicted gluten-free dietary adherence (i.e., integrated and identified regulations) and PA (i.e., intrinsic and identified regulations; p < .05). Findings may be used by health professionals to inform behavioural interventions consistent with OIT (Deci & Ryan, 2002).
    • Linking of stress offset score (SOS), work satisfaction, and organizational commitment to intentions to quit

      Alexander, Angela.; Applied Health Sciences Program (Brock University, 2007-05-21)
      The purpose of this study was to identify the impact of stressors and offsetting satistiers, measured in this study with Stress Offset Score (SOS), on intentions to quit and examine the mediating and moderating effects of three facets of work satisfaction (job satisfaction, pay satisfaction, and satisfaction with supervisor) and two facets of organizational commitment (affective and nonnative commitment) on this relationship. The sample was composed of 2990 employees from 21 public and private organizations. The interaction of each type of work satisfaction and organizational commitment, with SOS, was tested using Ordinary Least Squares (OLS) procedures. Intentions to quit was the dependent variable. The research questions were determine: (1) Does SOS predict intentions to quit? (2) Does work satisfaction mediate the predictive relationship of SOS on intentions to quit? (3) Does organizational commitment mediate the predictive relationship of SOS on intent to quit? (4) Does work satisfaction moderate the predictive relationship of SOS on intentions to quit? and (5) Does organizational commitment moderate the predictive relationship of SOS on intentions to quit? The results indicated that SOS was negatively correlated with intentions to quit. Each of the types of work satisfaction and organizational commitment variables showed a partial mediated relationship with SOS and each relationship was highly significant, while normative commitment explained more of the relationship then other mediators. The study also tested for interactions but no statistical significant relationships where established between any of the interaction terms (e.g., SOSxJob Satisfaction and SOSxAffcctive Commitment) and intentions to quit.
    • Low-dose lithium supplementation and SERCA uncoupling in C2C12 cells and murine skeletal muscle.

      Geromella, Mia Sara; Applied Health Sciences Program
      Adaptive thermogenesis is a cellular process that accelerates energy expenditure while increasing heat production in response to prolonged cold exposure or caloric excess. The prevalence of obesity along with its comorbidities is continually rising. Obesity is a result of energy intake superseding energy expenditure, however, a balance between energy intake versus energy expenditure is key in weight maintenance. Therefore, enhancing adaptive thermogenesis may be relevant in combatting diet-induced obesity. Skeletal muscle via sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) uncoupling and brown/beige adipose via mitochondrial uncoupling are the two sites for adaptive thermogenesis in mammals. Recent evidence has shown that glycogen synthase kinase 3 (GSK3) negatively regulates adipose-based thermogenesis by repressing uncoupling protein-1 expression in brown adipocytes. However, to our knowledge, no studies have examined whether GSK3 also negatively regulates muscle-based thermogenesis via SERCA uncoupling. The SERCA pump catalyzes the active transport of 2 Ca2+ ions into the sarcoplasmic reticulum per 1 ATP hydrolyzed under optimal conditions. Sarcolipin (SLN), an uncoupler of SERCA makes Ca2+ transport less efficient by reducing SERCA coupling ratio. The objective of this thesis was to determine whether GSK3 inhibition with low dose lithium (Li) supplementation can increase SLN expression and promote SERCA uncoupling in both C2C12 cells and in murine soleus muscle. Our results show that in C2C12 cells, 0.5mM LiCl promotes GSK3 inhibition and SERCA uncoupling via an increase in ryanodine receptor (RYR) but not SLN. In contrast, soleus muscles from chow-fed and lithium supplemented mice did not result in any notable changes in SERCA coupling ratio or the content of SERCA associated proteins. We next determined whether this would differ under an added stress of a high-fat diet. Our results show that soleus homogenates of HFD+Li supplemented mice have significant reductions in SERCA coupling ratio compared with HFD alone, which was presumably due to an increase in SERCA uncoupling proteins SLN and NNAT. Altogether these data suggest the potential role of GSK3 inhibition via low dose lithium supplementation in activating muscle-based thermogenesis, particularly under the stress of a HFD.
    • Low-dose lithium supplementation influences GSK3β activity in the brains of an early, diet-induced sporadic Alzheimer’s disease mouse model

      Fenech, Rachel; Applied Health Sciences Program
      Alzheimer’s disease (AD) is a neurodegenerative disease characterized by neurofibrillary tangles, amyloid-beta plaques, and cognitive decline. Research supports that key highlights of Type-2 Diabetes Mellitus (T2DM; i.e. obesity and insulin resistance) are significant risk factors for AD. At the forefront of both AD and T2DM pathologies is increased glycogen synthase kinase 3-β (GSK3β) activity. Targeting the inhibition of GSK3β has thus been suggested as an AD prophylactic. Lithium (Li), is a well-known natural GSK3β inhibitor, but is associated with dose-dependent adverse side effects. I thus aimed to examine the effects of low-dose Li supplementation on brain GSK3β activity, the development of AD pathologies, and markers of insulin signaling in a diet-induced insulin resistant mouse model. Male C57BL/6J mice were divided into either a 6-week (n = 24) or 12-week study (n = 72). In the 6-week study, mice were fed a chow diet (CON; n = 12) or a chow diet with Li-supplemented drinking water (Li; 10 mg / kg / day; n = 12) for 6 weeks. Alternatively, in the 12-week study, mice were fed a chow diet (CON; n = 24), a high-fat diet (HFD; 60% fat; n = 24), or a HFD with Li-supplemented drinking water (HFD+Li; n = 24) for 12 weeks. Prefrontal cortex and hippocampal tissues were collected for analysis. HFD and HFD+Li mice experienced significant weight gain and had impaired glucose and insulin tolerance compared to CON mice. Furthermore, HFD+Li mice had reduced caloric efficiency and rescued insulin degrading enzyme content compared to HFD mice. With respect to GSK3β activity, increases in inhibitory p-GSK3β Ser9 were not observed until 12 weeks in the HFD+Li compared to CON mice, however actual activity was reduced after only 6 weeks in the Li compared to CON mice. Collectively, these data provides evidence for low-dose Li supplementation to improve diet-induced impairments that can otherwise contribute to AD. Moreover, these results indicate that GSK3β activity can be inhibited despite any changes in phosphorylation. These findings contribute to an overall greater understanding of low-dose Li’s ability to influence GSK3β activity in the brain and its potential as an AD prophylactic.
    • Maternal High Fat Feeding: Impact of Female Offspring Body Composition and Bone Health

      Castelli, Laura; Applied Health Sciences Program (Brock University, 2014-09-05)
      High fat diet (HFD) consumption in rodents alters body composition and weakens bones. Whether female offspring of mothers consuming a HFD are similarly affected at weaning and early adulthood is unclear. This research determined whether maternal HFD contributes to long-lasting alterations in body composition and bone health of female offspring. Rats were fed control or HFD for 10 weeks prior to and throughout pregnancy and lactation. Female offspring were studied at weaning or 3 months of age (consumed control diet). Main findings in female offspring: maternal HFD decreased lean mass, increased fat mass and femoral BMD at weaning, but not at 3 months; weanling femoral lipid composition reflected maternal diet, persisting to 3 months of age (decreased total and n6 polyunsaturates, increased saturates); and no differences in femoral strength at 3 months. In summary, 3 month old female offspring have similar body composition and bone health regardless of maternal diet.
    • Mechanisms of endothelin-1 induced reactive oxygen species production in vascular adventitial fibroblasts

      Chapman, Sandy.; Applied Health Sciences Program (Brock University, 2008-06-15)
      With the relationship between endothelin-1 (ET-1) stimulation and reactive oxygen species (ROS) production unknown in adventitial fibroblasts, I examined the ROS response to ET-1 and angiotensin (Ang II). ET-1 -induced ROS peaked following 4 hrs of ET-1 stimulation and was inhibited by an ETA receptor antagonist (BQ 123, 1 uM) an extracellular signal-regulated kinase (ERK) 1/2 inhibitor (PD98059, 10 uM), and by both a specific, apocynin (10 uM), and non-specific, diphenyleneiodonium (10 uM), NAD(P)H oxidase inhibitor. NOX2 knockout fibroblasts did not produce an ET-1 induced change in ROS levels. Ang II treatment increased ROS levels in a biphasic manner, with the second peak occurring 6 hrs following stimulation. The secondary phase of Ang II induced ROS was inhibited by an ATi receptor antagonist, Losartan (100 uM) and BQ 123. In conclusion, ET-1 induces ROS production primarily through an ETA-ERKl/2 NOX2 pathway, additionally, Ang II-induced ROS production also involves an ETa pathway.
    • Mediating Influence of Physical Fitness on the Relationship between Academic Performance and Motor Proficiency

      Alexander, Ryan; Applied Health Sciences Program (Brock University, 2011-08-10)
      We explored the potential mediating influence of physical fitness on the relationship between academic performance and motor proficiency in children. 1864 students (F:926, M:938, age 11.91 (SD:0.34). Academic achievement was derived from an average of standardized tests of reading, writing, and math. The Bruininks-Oseretsky Test of Motor Performance (short-form) determined motor proficiency. Fitness (peak oxygen uptake) was established with the Léger 20-m Shuttle Run Test. OLS regression identified several significant predictors of academic performance. After controlling for age (p=0.0135), gender (p<0.0001), and parental education (p<0.0001), motor proficiency (p<0.0001), was significant. After adding physical fitness (p=0.0030) to the model the effect of motor proficiency remained significant however the point estimate was reduced from 0.0034 (p<0.0001) to 0.0026 (p<0.0001). These results suggest that physical fitness plays a mediating role on the relationship between academic performance and motor proficiency although both aerobic fitness and motor proficiency have independent roles.
    • The Mediating Role of Perceived Scholastic Competence in the Relationship Between Motor Coordination and Academic Performance

      Lemay, Alex; Applied Health Sciences Program
      Children with developmental coordination disorder (DCD) are often referred to as clumsy because of their compromised motor coordination. Clumsiness and slow movement performances while scripting in children with DCD often result in poor academic performance and a diminished sense of scholastic competence. This study purported to examine the mediating role of perceived scholastic competence in the relationship between motor coordination and academic performance in children in grade six. Children receive a great deal of comparative information on their academic performances, which influence a student's sense of scholastic competence and self-efficacy. The amount of perceived academic self-efficacy has significant impact on academic performance, their willingness to complete academic tasks, and their self-motivation to improve where necessary. Independent t-tests reveal a significant difference (p < .001) between DCD and non-DCD groups when compared against their overall grade six average with the DCD group performing significantly lower. Independent t-tests found no significant difference between DCD and non-DCD groups for perceived scholastic competence. However, multiple linear regression analysis revealed a significant mediating role of 15% by perceived scholastic competence when examining the relationship between motor coordination and academic performance. While children with probable DCD may not rate their perceived scholastic competence as less than their healthy peers, there is a significant mediating effect on their academic performance.
    • Menstrual Cycle Related Fluctuations in Circulating Markers of Bone Metabolism at Rest and in Response to Running in Eumenorrheic Females

      Guzman, Anne; Applied Health Sciences Program
      The aim of this study was to investigate potential fluctuations in bone metabolic markers across the menstrual cycle both at rest and after a 30-minute bout of vigorous-intensity running at 80% of �̇ O₂max. Resting and post-exercise (0, 30, 90 min) sclerostin (inhibitor of bone formation), parathyroid hormone (PTH, regulator of calcium homeostasis), carboxy-terminal cross-linking telopeptide of type I collagen (β-CTX, marker of bone resorption), and procollagen type 1 N propeptide (P1NP, marker of bone formation) were assessed in 10 young, eumenorrheic women (21.7 ± 3.2 years, 23.2 ± 3 kg. m2 ) during the mid- to late-follicular (FP: day 8.0 ± 1.4) and midluteal (LP: day 22.0 ± 2.5) phases of the menstrual cycle. Ovulation was determined using ovulation kits and daily measurement of oral body temperature upon awakening. Menstrual phase was subsequently confirmed by measurement of plasma estradiol and progesterone taken on study days, confirming an increase in both hormones during the mid-luteal phase. At rest, there were no significant differences in sclerostin (FP: 266.5 ± 48.6 pg·mL-1 ; LP: 296.0 ± 37.5 pg·mL-1 ; p=0.507), PTH (FP: 1.00 ± 0.22 pmol·L-1 ; LP: 0.71 ± 0.16 pmol·L-1 ; p=0.485), β-CTX (FP: 243.1± 52.7 ng·mL-1 ; LP: 202.4 ± 30.8 ng·mL-1 ; p=0.691), or P1NP (FP: 56.9 ± 11.30 ng·mL-1 ; LP: 64.30 ± 18.32 ng·mL-1 ; p=0.133) between menstrual cycle phases. As there were no main effects for menstrual phase and no significant interaction, post-exercise responses did not differ between menstrual phases for any of the markers. Significant main effects for time were found in sclerostin, PTH, β-CTX and P1NP. Specifically, sclerostin and PTH increased from pre- to immediately postexercise (+46% and +43%, respectively; p<0.0001), then returned to resting concentrations at 30 min post-exercise. P1NP also increased immediately post-exercise (+29%; p<0.0001), returning to resting concentrations at 30 min post-exercise. β-CTX decreased from pre- to immediately postexercise (-20%; p=0.004) and remained below its pre-exercise concentrations at 30 min postexercise (-12%; p=0.039) and 90 min post-exercise (-17%; p=0.002). These results demonstrate that sclerostin, PTH, β-CTX and P1NP do not differ at rest or in response to exercise across the menstrual cycle.
    • Menstrual status and thermoregulatory responses of active adolescents during exercise in a cold environment

      Cunliffe, Melora.; Applied Health Sciences Program (Brock University, 2002-05-21)
      This study examined the interactions between the reproductive status and the thermoregulatory responses during exercise in the cold in girls involved in competitive sports. Four girls with established menstrual cycles comprised the eumenorrheic menarcheal group (EM) and 5 non-menstruating girls comprised the pre-menarcheal group (PM). During the first visit maximal oxygen consumption, height, weight and percent body fat (%BF) were measured. The second visit involved: a determination of metabolic rate in thermoneutrality (21°C) involving 10-min rest and 20-min cycling (30% of VCL max), and a cold stress test (5°C, 40% humidity, <0.3 m/s air velocity) involving 20-min rest and 40-min cycling (30% of VCL max.). Subjects in the EM group were tested twice in the chamber during the follicular and luteal phases. Pre-menarcheal subjects were found to have significantly (p<0.05) lower core temperatures during the final stages of cold exposure. Overall, body fat was not significantly correlated with core temperature in the cold, however there was a significant surface-to-mass ratio difference between the groups. While in the follicular phase, EM girls had a higher core temperature during cold exposure. Therefore, reproductive hormonal status seems to be an important factor in terms of cold tolerance in females during adolescence.
    • Migrations and gradations : reappraising the health profile of immigrants to Canada

      Hawes, Robert Alexander.; Applied Health Sciences Program (Brock University, 2005-06-15)
      New immigrants to Canada typically have a more favourable health profile than the non-immigrant population. This phenomenon, known as the 'healthy immigrant effect', has been attributed to both the socioeconomic advantage (ie. educational attainment, occupational opportunity) of non-refugee immigrants and existing screening protocols that admit only the healthiest of persons to Canada. It has been suggested that this health advantage diminishes as the time of residence in Canada increases, due in part to the adoption of health-risk behaviours such as alcohol and cigarette use, an increase in excess body weight, and declining rates of physical activity. However, the majority of health research concerning immigrants to Canada has been limited to cross-sectional studies (Dunn & Dyck, 2000; Newbold & Danforth, 2003), which may mask an immigrant-specific cohort effect. Furthermore, the practice of aggregating foreign-bom persons by geographical regions or treating all immigrants as a homogeneous group may also obfuscate intra-immigrant differences in health. Accordingly, this study uses the Canadian National Population Health Surveys (NPHS) and data from the United Nations Development Program (UNDP) to prospectively evaluate factors that predict health status among immigrants to Canada. Each immigrant in the NPHS was linked to the UNDP Human Development Index of their country of birth, which uses a combined measure of health, education, and per capita income of the populace. The six-year change in health function, psychological distress, and self-rated health were considered from a population health perspective (Evans, 1994), using generalized-estimating equations (GEE) to examine the compounding effect of past and recent predictors of health. Demographic
    • Mindfulness therapy as a means to improve sexual satisfaction in couples with neuromuscular disabilities

      Seliman, Merna; Applied Health Sciences Program
      Research regarding sexuality after neuromuscular disabilities has focused on either men or women separately, without considering the couple and how acquiring a disability may influence relationships. The objective of this study was to investigate the effects of an 8-week modified mindfulness intervention on sexual satisfaction in couples where one or both partners are living with neuromuscular disability. One couple (male age 42, female age 44) with the female living with neuromuscular disability (relapsing remitting MS, 11 years since diagnosis) participated in the study. The mindfulness intervention was administered to participants via a booklet and the exercises were explained verbally after the baseline interview. The booklet contained a total of eight mindfulness-based exercises for each week of the intervention. The exercises were explained in a step-by-step manner in the booklet. The booklet also included reflection questions at the end of each exercise in order to prompt the couple to journal about their experiences and record how much time they dedicated to that exercise per week. The exercises were carried out at home. The intervention also included a psycho-education session that was offered at week five of the intervention. The psycho-education session aimed to challenge thought patterns and negative beliefs about sex and physical abilities. It also involved a discussion about body-image as it relates to mindfulness. Testing involved a sexual satisfaction questionnaire that was completed by each member of the couple individually at baseline and at the end of the 8-week intervention. II Also, an in-depth semi-structured phenomenological interview of the couple together was conducted at baseline and at the end of the 8-week intervention. The results of this study showed that sexual satisfaction and sexual-self view have improved for the couple as a result of participating in the 8-week mindfulness intervention. In addition, the couple reported an improvement in communication, understanding, and awareness. Sensate focus exercises enhanced intimacy between the couple. Themes such as acceptance and feeling present in the moment were discerned from phenomenological analysis. These findings show promise for mindfulness-based therapies to enhance sexual satisfaction and relationship satisfaction in couples living with neuromuscular disabilities.
    • Mood Disorder and Hypertension Among Canadian Older Adults with Different Religious Affiliations: A Cross-sectional Analysis of the Baseline Data from the CLSA

      Giancaterino, Michael; Applied Health Sciences Program
      Background: The relationship between mood disorder and hypertension is not well understood among Canadian older adults. No research has examined whether religiosity has any impact on this relationship in a Canadian older adult population. Objectives: To examine i) the association between mood disorder and hypertension among older Canadian older adults and ii) if religion had an impact on this association Methods: Baseline data from the CLSA of 44,920 males and females aged 45 years and older was collected. Mood disorder and hypertension were defined by self-reported clinical diagnosis. Religious affiliation was categorized into two groups: no religious affiliation or some religious affiliation. Among religiously affiliated participants, religious attendance was categorized into four groups; daily/weekly, monthly, yearly and never in the past 12 months. Among non-religiously affiliated participants, religious attendance was categorized into two groups; no attendance and any form of attendance in the past 12 months. Logistic regression was used to assess the relationship between mood disorder, religious affiliation, religious attendance and hypertension. Age-related trends were also examined to see if any of the associations differed among different age groups. Results: The odds of reporting hypertension increased with self-reported mood disorder and/or religious affiliation by 27% (OR, [95% CI]: 1.27, [1.16, 1.39]) and 13% (OR, [95% CI]: 1.13, [1.04, 1.23]), respectively. As attendance to religious services and events increased, the magnitude of association between religious affiliation and hypertension decreased (OR, [95% CI]: 1.20 [1.09, 1.33] to 1.02, [0.92, 1.13]). Among religiously affiliated, the decrease in magnitude was more apparent (OR, [95% CI]: 1.01 [0.91, 1.12] to 0.85, [0.77, 0.93]). Conclusion: This study suggests that there is an association between mood disorder and hypertension, with the presence of mood disorder increasing the odds of hypertension. Similarly, being religiously affiliated seems to share a similar relationship with hypertension. To note, it seems as though the magnitude of the association between religious affiliation and hypertension decreases with increased attendance. This study will help to grow the ever-growing body of religious related literature and will be crucial in understanding the multifaceted nuanced nature of religion. Key Words: mood disorder, hypertension, religion, affiliation, CLSA
    • Muscle strength and activation characteristics of power- trained and non-athlete boys and men

      Mitchell, Cameron Jeffrey.; Applied Health Sciences Program (Brock University, 2009-02-16)
      During maturation, muscle strength is enhanced through muscle growth, although neuro-muscular factors are also believed to be involved. In adults, training for power sports has been shown to enhance muscle strength and activation. The purpose of this study was to examine muscle strength and activation in power-trained athletes (POW) compared with non-athletes (CON), in boys and in adults. After familiarization subjects performed ten 5-s explosive maximal voluntary contractions for elbow and knee flexion and extension. The adults were stronger then the boys and the adult POW were stronger then the adult CON, even after correction for muscle size. Normalized rate of torque development was higher in the adults then in the boys and higher in the POW then CON boys. The rate of muscle activation was higher in the adults and POW groups. The results suggest that maturation and power-training have an additive effect on muscle activation.
    • Muscle Up: Psychobiological Responses to Social-Evaluative Body Image Threats in University Male Athletes and Non-Athletes

      Brown, David; Applied Health Sciences Program
      Negative body image often occurs as a result of social evaluation of the physique in men. However, athletes tend to experience fewer body image concerns compared to non-athletes. Social-self preservation theory (SSPT) holds that social-evaluative threats (SETs) elicit consistent psychobiological responses (salivary cortisol and shame) to protect one’s social-esteem, status, and standing. Actual body image SETs have shown consistent psychobiological changes consistent with SSPT in men, however, these responses in athletes have yet to be examined due to the unique relationship they have with their bodies. Thus, the purpose of the current study was to examine psychobiological (i.e., body dissatisfaction and shame and salivary cortisol) responses to an acute laboratory body image SET in 49 male varsity athletes and 63 non-athletes from a university community between the ages of 18 and 28 years old. Participants were randomized into a high or low body image SET conditions, stratified by athlete status, and measures of body dissatisfaction and shame and salivary cortisol were taken across the session. Results showed significant time-by-condition interactions, such that athletes and non-athletes had significant increases in salivary cortisol, when controlling for baseline values, and state body shame 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 university non-athletes and university male athletes from non-aesthetic sports. By contrast, previous studies have found that elite level athletes showed blunted psychobiological responses to performance based SETs compared to non-exercisers. It is possible that athletes in the present study did not compete at a high enough level to reduce the effects of SETs; it is also possible that differences in sport type between the athletes in the current study and those in previous studies may explain differences in findings. It is also possible that body image threats lead to unique responses compared to more general, performance-based threats. Future research should continue to examine the relationship between athletes and their body image by investigating the impact of competition level and sport type within a Canadian university sport context.
    • Myosin Regulatory Light Chain Phosphorylation and Its Effect on the Contractile Economy of Mouse Fast Muscle

      Bunda, Jordan; Applied Health Sciences Program
      Activated by elevations in myoplasmic calcium concentration, myosin light chain kinase (skMLCK) phosphorylates the regulatory light chains (RLCs) of fast muscle myosin. This covalent modification potentiates force production, but requires an investment of ATP. Our objective was to investigate the effect of RLC phosphorylation on the contractile economy (mechanical output:metabolic input) of fast twitch skeletal muscle. Extensor digitorum longus muscles isolated from Wildtype and skMLCK-/- mice mounted in vitro (25°C) were subjected to repetitive low-frequency stimulation (10Hz,15s) known to cause activation of skMLCK, and staircase potentiation of force. With a 3-fold increase in RLC phosphate content, Wildtype generated 44% more force than skMLCK-/- muscles over the stimulation period (P = .002), without an accompanied increase in energy cost (P = .449). Overall, the contractile economy of Wildtype muscles, with an intact RLC phosphorylation mechanism, was 73% greater than skMLCK /- muscles (P = .043), demonstrating an important physiological function of skMLCK during repetitive contractile activity.
    • The nature experiences of wilderness recreation leaders : throwing a stone

      Grimwood, Bryan S. R.; Applied Health Sciences Program (Brock University, 2005-05-21)
      Through this descriptive exploratory study, the ways that wilderness recreation leaders experience nature are illuminated, deconstructing the assumed environmental benefits of and practices used in outdoor recreation (Haluza-Delay, 2001). This study also offers a foundation for advancing an environmental ethic among wilderness recreation leaders, participants, and organizations. With the continued degradation of and threats to natural environments, and the rising popularity of outdoor recreation participation, the outdoor recreation professional can be a leader in promoting human reconnections to the Earth (Henderson, 1999). Leaders of outdoor recreation experiences play an important role in encouraging these revived relationships to natural settings and can contribute to the necessary environmental consciousness shift needed within Western society (Hanna, 1995; Jordan, 1996). The purpose of this research was to describe the lived-experience in nature of wilderness recreation leaders. Specifically, a phenomenological method of inquiry was used to describe the meaning of nature, the connections and relationships to nature, and the behaviours and emotions experienced in nature by a group of wilderness canoe trip leaders employed by a residential summer camp. In addition to the implications of this research, achieving this outcome provides a rich descriptive understanding of wilderness leaders' experiences—a basis from which to extend future research endeavours and programmatic practices that promote effective environmental outcomes of outdoor recreation participation. Each of the five study participants was employed in the summer of 2003 by an Ontario residential summer camp organization that sponsors extended wilderness river canoe trips for youth. Two in-depth and semi-structured interviews were performed with each participant, asking them to reflect on the canoe trip that they led for the summer camp organization during 2003. Phenomenological data was analyzed according to Colaizzi's (1978) thematic analysis process. Consistent with van Manen's (1997) emphasis on phenomenological writing, the final result presents the essence of the nature experiences of wilderness recreation leaders in the format of a narrative description. This narrative piece is the culmination of this research effort. Throughout the journey, however, various foundations within the outdoor recreation field, such as minimum impact principles, environmentally responsible behaviours, anthropocentric and ecocentric worldviews, and effective leadership are deconstructed and discussed.
    • Neuromotor Mechanisms Involved in the Recovery from Local Muscular Fatigue

      Green, Lara; Applied Health Sciences Program (Brock University, 2013-01-14)
      The phenomenon of over-recovery consists of a participant’s maximal force levels returning to values above initial levels. The present study examined the presence and causes of over-recovery following local muscular fatigue. Fourteen males completed two fatigue protocols consisting of maximal isometric dorsiflexion contractions. Upon completion of the fatigue protocol participants’ force was monitored over a 15 minute recovery period. Dorsiflexion force and surface electromyography (sEMG) from the tibialis anterior and soleus were monitored concurrently. Following the two fatigue conditions (10 and 20% force decrement) force recovered to 100.5 and 99.5% of initial levels for each condition, respectively. Surface EMG root-mean-square amplitude and MPF exhibited changes consistent with a warm-up effect. It was concluded that over-recovery was not present in the tibialis anterior following a local muscular fatigue. However, the return in force to initial values, rather than a persistent decrement as normally observed, was mediated by the warm-up effect.