• The Impact of Motor Task Success on the Perception of Target Size

      Bianchi, Krystina; Applied Health Sciences Program
      The action-specific perception literature has demonstrated that superior task success is correlated with perceiving task-related objects as appearing larger. Using a putting task, the present study examined this relationship under three different practice conditions (errorless, errorful, and self-control) while perceiving the size of the putting hole at various distances from the putting hole (25 cm, 50 cm, 75 cm, 100 cm, 125 cm, 150 cm, 175 cm, 200 cm). The acquisition and retention data revealed that there was no correlation between superior task success and larger perceived putting hole sizes. Additionally, it was found that the perceived putting hole sizes that were recorded at the end of acquisition were robust enough to persist over a 24-hour retention interval to exist before the first trial of retention. The results of the present study introduce inconsistencies with the current action-specific literature, while adding a novel contribution to the literature regarding perception retention.
    • The impact of social competence between physical activity and motor performance

      Martin, Britney; Applied Health Sciences Program (Brock University, 2013-04-18)
      Objective: To identify the association of low physical activity (PA) participation in children with various motor performances (MP) and to establish the impact of social competence (SC). Methods: Sixth grade children from PHAST study at Brock University (n=1958; 50.53% males) had MP test results from Bruininks-Oseretsky Test of Motor Proficiency, Participation Questionnaire (PQ) used for PA and Harter Social Competence Scale for self-perceived SC. Comparative tests, multiple and logistic regressions were performed. Results: Significant differences in PQ measures in MP quartiles and SCs. MP and SC are independent predictors of PA (p<.05) except with SES on free play activity, making MP not significant. Lower MP increased the odds of low total PA and organized sport participation but not for free play activities (OR~1). Higher SC reduced the risk of low participation in all PA measures. Conclusions: SC improves PA participation, including free play and organized sports, despite the child’s MP.
    • The impact of tobacco control policies on university students' smoking in Ontario

      Dupuis, Sandy.; Applied Health Sciences Program (Brock University, 2007-11-04)
      Objective. Despite steady declines in the prevalence of tobacco use among Canadians, young adult tobacco use has remained stubbornly high over the past two decades (CTUMS, 2005a). Currently in Ontario, young adults have the highest proportion of smokers of all age cohorts at 26%. A growing body of evidence shows that smoking restrictions and other tobacco control policies can reduce tobacco use and consumption among adults and deter initiation among youth; whether young adult university students' smoking participation is influenced by community smoking restrictions, campus tobacco control policies or both remains an empirical question. The purpose of this study is to examine the relationship among current smoking status of students on university campuses across Ontario and various tobacco control policies, 3including clean air bylaws of students' home towns, clean air by-laws of the community where the university is situated, and campus policies. Methods. Two data sets were used. The 200512006 Tobacco Use in a Representative Sample of Post-Secondary Students data set provides information about the tobacco use of 10,600 students from 23 universities and colleges across Ontario. Data screening for this study reduced the sample to 5,114 17-to-24 year old undergraduate students from nine universities. The second data set is researcher-generated and includes information about strength and duration of, and students' exposure to home town, local and campus tobacco control policies. Municipal by-laws (of students' home towns and university towns) were categorized as weak, moderate or strong based on criteria set out in the Ontario Municipal By-law Report; campus policies were categorized in a roughly parallel fashion. Durations of municipal and campus policies were calculated; and length of students' exposure to the policies was estimated (all in months). Multinomial logistic regression analyses were used to examine the relationship between students' current smoking status (daily, less-than-daily, never-smokers) and the following policy measures: strength of, duration of, and students' exposure to campus policy; strength of, duration of, and students' exposure to the by-law in the university town; and, strength of, duration of, and students' exposure to the by-law in the home town they grew up in. Sociodemographic variables were controlled for. Results. Among the Ontario university students surveyed, 7.0% currently use tobacco daily and 15.4% use tobacco less-than-daily. The proportions of students experiencing strong tobacco control policies in their home town, the community in which their university is located and at their current university were 33.9%,64.1 %, and 31.3% respectively. However, 13.7% of students attended a university that had a weak campus policy. Multinomial logistic regressions suggested current smoking status was associated with university town by-law strength, home town by-law strength and the strength of the campus tobacco control policy. In the fmal model, after controlling for sociodemographic factors, a strong by-law in the university town and a strong by-law in students' home town were associated with reduced odds of being both a less-than-daily (OR = 0.64, 95%CI: 0.48-0.86; OR = 0.80, 95%CI: 0.66-0.95) and daily smoker (OR = 0.59, 95%CI: 0.39-0.89; OR = 0.76, 95%CI: 0.58-0.99), while a weak campus tobacco control policy was associated with higher odds of being a daily smoker (OR = 2.08, 95%CI: 1.31-3.30) (but unrelated to less-than-daily smoking). Longer exposure to the municipal by-law (OR = 0.93; 95%CI: 0.90-0.96) was also related to smoking status. Conclusions. Students' smoking prevalence was associated with the strength of the restrictions in university, and with campus-specific tobacco control policies. Lessthan- daily smoking was not as strongly associated with policy measures as daily smoking was. University campuses may wish to adopt more progressive campus policies and support clean air restrictions in the broader community. More research is needed to determine the direction of influence between tobacco control policies and students' smoking.
    • Implementing the OPTIMAL model : the impact on students' motivation in an elementary school games environment

      Sheppard, Joanna C.; Applied Health Sciences Program (Brock University, 2005-05-21)
      Optimal challenge occurs when an individual perceives the challenge of the task to be equaled or matched by his or her own skill level (Csikszentmihalyi, 1990). The purpose of this study was to test the impact of the OPTIMAL model on physical education students' motivation and perceptions of optimal challenge across four games categories (i. e. target, batting/fielding, net/wall, invasion). Enjoyment, competence, student goal orientation and activity level were examined in relation to the OPTIMAL model. A total of 22 (17 M; 5 F) students and their parents provided informed consent to take part in the study and were taught four OPTIMAL lessons and four non-OPTIMAL lessons ranging across the four different games categories by their own teacher. All students completed the Task and Ego in Sport Questionnaire (TEOSQ; Duda & Whitehead, 1998), the Intrinsic Motivation Inventory (IMI; McAuley, Duncan, & Tanmien, 1987) and the Children's Perception of Optimal Challenge Instrument (CPOCI; Mandigo, 2001). Sixteen students (two each lesson) were observed by using the System for Observing Fitness Instruction Time tool (SOFTT; McKenzie, 2002). As well, they participated in a structured interview which took place after each lesson was completed. Quantitative results concluded that no overall significant difference was found in motivational outcomes when comparing OPTIMAL and non-OPTIMAL lessons. However, when the lessons were broken down into games categories, significant differences emerged. Levels of perceived competence were found to be higher in non-OPTIMAL batting/fielding lessons compared to OPTIMAL lessons, whereas levels of enjoyment and perceived competence were found to be higher in OPTIMAL invasion lessons in comparison to non-OPTIMAL invasion lessons. Qualitative results revealed significance in feehngs of skill/challenge balance, enjoyment and competence in the OPTIMAL lessons. Moreover, a significance of practically twice the active movement time percentage was found in OPTIMAL lessons in comparison to non-OPTIMAL lessons.
    • The implications of being an international medical graduate (IMG) in Canadian society : a qualitative study of foreign-trained physicians' resettlement, sense of identity and health status

      de Carvalho, Maria Auxiliadora Junqueira.; Applied Health Sciences Program (Brock University, 2007-05-21)
      This qualitative research study used grounded theory methodology to explore the settlement experiences and changes in professional identity, self esteem and health status of foreign-trained physicians (FTPs) who resettled in Canada and were not able to practice their profession. Seventeen foreign-trained physicians completed a pre-survey and rated their health status, quality of life, self esteem and stress before and after coming to Canada. They also rated changes in their experiences of violence and trauma, inclusion and belonging, and racism and discrimination. Eight FTPs from the survey sample were interviewed in semi-structured qualitative interviews to explore their experiences with the loss of their professional medical identities and attempts to regain them during resettlement. This study found that without their medical license and identity, this group of FTPs could not fully restore their professional, social, and economic status and this affected their self esteem and health status. The core theme of the loss of professional identity and attempts to regain it while being underemployed were connected with the multifaceted challenges of resettlement which created experiences of lowered selfesteem, and increased stress, anxiety and depression. They identified the re-licensing process (cost, time, energy, few residency positions, and low success rate) as the major barrier to a full and successful settlement and re-establishment of their identities. Grounded research was used to develop General Resettlement Process Model and a Physician Re-licensing Model outlining the tasks and steps for the successfiil general resettlement of all newcomers to Canada with additional process steps to be accomplished by foreign-trained physicians. Maslow's Theory of Needs was expanded to include the re-establishment of professional identity for this group to re-establish levels of safety, security, belonging, self-esteem and self-actualization. Foreign-trained physicians had established prior professional medical identities, self-esteem, recognition, social status, purpose and meaning and bring needed human capital and skills to Canada. However, without identifying and addressing the barriers to their full inclusion in Canadian society, the health of this population may deteriorate and the health system of the host country may miss out on their needed contributions.
    • The Influence of Burnout Symptoms on the Relationship between Work-Life Balance and Self-Rated Health

      Novess, Jennafer; Applied Health Sciences Program
      The effects of stress at work are estimated to cost Canadian employers more than 20 billion dollars annually through absenteeism, sick leave and decreased productivity. Over the past two decades, Canadians have reported higher stress levels, increased work hours and more work performed outside of normal business hours. This work-life imbalance has far-reaching repercussions–affecting an employee’s performance as well as their health. Chronic exposure to these high levels of stress can also lead to burnout. The primary purpose of this study was to determine the magnitude in which burnout symptoms influence the relationship between work-life balance and self-rated health. The secondary purpose of this study was to determine if gender and age interactions exist in the relationship between burnout, work-life balance, and self-rated health. This cross-sectional study involved secondary analysis of 220 managers, workers and human service professionals who completed an Occupational Health Clinics for Ontario Workers’ Mental Injury Toolkit (MIT) survey for the launch of the MIT. The MIT survey is a modified form of the short version of the Copenhagen Psychosocial Questionnaire and includes expanded questioning around burnout, stress, sleep troubles, cognitive, and somatic symptoms. There were no significant differences in self-rated health based on a respondent’s gender or age, indicating that no interaction of gender and age would be required. Respondents with low self-rated health reported significantly higher burnout and work-life imbalance compared to those with high self-rated health. The regression analysis demonstrated that the magnitude in which burnout mediates the relationship between work-life balance and self-rated health was 96%. These findings support previous studies that associate high levels of work-life imbalance or burnout with poor self-rated health or health outcomes. In this study, the shared variance between work-life balance and burnout also supports recent efforts to redefine the context and causes of burnout to include non-work factors. Based on our findings, the potential exists for the development of workplace health promotion strategies that address maintaining a balance between work and home as they may improve employee health and reduce burnout.
    • The influence of cognitive resources on compensatory arm responses

      Laing, Justin Michael; Applied Health Sciences Program (Brock University, 2014-10-10)
      The purpose of this study was to determine the influence of an ongoing cognitive task on an individual’s ability to generate a compensatory arm response. Twenty young and 16 older adults recovered their balance from a support surface translation while completing a cognitive (counting) task of varying difficulty. Surface electromyographic (EMG) recordings from the shoulders and kinematics of the right arm were collected to quantify the compensatory arm response. Results indicated that the counting task, regardless of its difficulty as well as the age of the individual, had minimal influence on the onset or magnitude of arm muscle activity that occurred following a loss of balance. In contrast to previous research, this study’s findings suggest that the cortical or cognitive resources utilized by the cognitive task are not relied upon for the generation of compensatory arm responses and that older adults are not disproportionately affected by dual-tasking than young adults.
    • The influence of drug-induced dyskinesias on manual tracking in Parkinson's disease

      Lemieux, Sarah.; Applied Health Sciences Program (Brock University, 2005-06-15)
      The influence of peak-dose drug-induced dyskinesia (DID) on manual tracking (MT) was examined in 10 dyskinetic patients (OPO), and compared to 10 age/gendermatched non-dyskinetic patients (NDPD) and 10 healthy controls. Whole body movement (WBM) and MT were recorded with a 6-degrees of freedom magnetic motion tracker and forearm rotation sensors, respectively. Subjects were asked to match the length of a computer-generated line with a line controlled via wrist rotation. Results show that OPO patients had greater WBM displacement and velocity than other groups. All groups displayed increased WBM from rest to MT, but only DPD and NDPO patients demonstrated a significant increase in WBM displacement and velocity. In addition, OPO patients exhibited excessive increase in WBM suggesting overflow DID. When two distinct target pace segments were examined (FAST/SLOW), all groups had slight increases in WBM displacement and velocity from SLOW to FAST, but only OPO patients showed significantly increased WBM displacement and velocity from SLOW to FAST. Therefore, it can be suggested that overflow DID was further increased with increased task speed. OPO patients also showed significantly greater ERROR matching target velocity, but no significant difference in ERROR in displacement, indicating that significantly greater WBM displacement in the OPO group did not have a direct influence on tracking performance. Individual target and performance traces demonstrated this relatively good tracking performance with the exception of distinct deviations from the target trace that occurred suddenly, followed by quick returns to the target coherent in time with increased performance velocity. In addition, performance hand velocity was not correlated with WBM velocity in DPO patients, suggesting that increased ERROR in velocity was not a direct result of WBM velocity. In conclusion, we propose that over-excitation of motor cortical areas, reported to be present in DPO patients, resulted in overflow DID during voluntary movement. Furthermore, we propose that the increased ERROR in velocity was the result of hypermetric voluntary movements also originating from the over-excitation of motor cortical areas.
    • Influence of Estrogen on RLC Phosphorylation and Posttetanic Potentiation of Mouse Muscles with and without Skeletal Myosin Light Chain Kinase

      Fillion, Melissa; Applied Health Sciences Program
      Estrogen may influence myosin regulatory light chain (RLC) phosphorylation and posttetanic potentiation (PTP) in mouse fast twitch muscle; although the signalling pathway for this effect is unknown. The purpose of this study was to test the hypothesis that previously reported estrogen effects on RLC phosphorylation and PTP are mediated via skeletal myosin light chain kinase (skMLCK). To this end, extensor digitorum longus (EDL) muscles from female wildtype and skMLCK deficient (skMLCK-/-) mice were divided into four groups: ovariectomized (OVX) with estrogen (E+), ovariectomized without estrogen (E-), sham surgery (Sham) and intact baseline (BL). At 8 weeks of age, mice in the OVX groups were ovariectomized followed by pellet implantation at 9 weeks of age with either a 0.1 mg of 17β-Estradiol or implantation of a placebo pellet (E+ and E- respectively); sham surgeries were also performed at this time point for both genotypes. Two weeks later EDL muscles were isolated and suspended in vitro (25° C) for determination of RLC phosphorylation and PTP, except for BL groups which began contractile experiments at 9 weeks. Our results showed that RLC phosphorylation measured in muscles frozen immediately after a potentiating stimulus was not different across conditions within either genotype although values for wildtype muscles were significantly (P<0.05) greater than skMLCK-/- muscles. Consistent with these findings, the ratio of concentric twitch force (post PS / pre PS) for wildtype and skMLCK-/- muscles was similar between E+ and E+ groups although values for wildtype were greater than skMLCK-/- muscles (all data P < 0.05). However, we were unable to directly test our hypothesis as a result of unaltered estradiol levels following OVX. The inability to validate estrogen’s beneficial influence on muscle strength and contractibility in this model could be a direct result of interference with further development and growth during estrogen supplementation. Future studies should note the importance of both estrous cycles and further growth of adult mice when working with ovarian hormones. Both of these factors were likely causes of our atypical findings.
    • INFLUENCE OF INCREASED EXTRACELLULAR LEUCINE ON THE PROTEIN METABOLIC RESPONSES DURING OSMOTIC STRESS IN SKELETAL MUSCLE

      Dunbar, Brittany; Applied Health Sciences Program
      The purpose of this study was to examine the effects of increased extracellular leucine concentration on protein metabolism in skeletal muscle cells when exposed to 3 different osmotic stresses. L6 skeletal muscle cells were incubated in either a normal or supplemental leucine (1.5mM) medium set to hypo-osmotic (230 ± 10 Osm), iso-osmotic (330 ± 10 Osm) or hyper-osmotic (440 ± 10 Osm) conditions. 3H-tyrosine was used to quantify protein synthesis. Western blotting analysis was performed to determine the activation of mTOR, p70S6k, ubiquitin, actin, and μ-calpain. Hypo-osmotic stress resulted in the greatest increase in protein synthesis rate under the normal-leucine condition while iso-osmotic stress has the greatest increase under the elevated-leucine condition. Elevated-leucine condition had a decreased rate in protein degradation over the normal condition within the ubiquitin proteasome pathway (p<0.05). Leucine and hypo-osmotic stress therefore creates a favourable environment for anabolic events to occur.
    • THE INFLUENCE OF LENGTH CHANGE SPEED AND DIRECTION ON DYNAMIC FUNCTION POTENTIATION IN FAST MOUSE MUSCLE

      Caterini, Daniel; Applied Health Sciences Program (2013-04-01)
      The purpose of this study was to test the hypothesis that the potentiation of dynamic function was dependent upon both length change speed and direction. Mouse EDL was cycled in vitro (250 C) about optimal length (Lo) with constant peak strain (± 2.5% Lo) at 1.5,3.3 and 6.9 Hz before and after a conditioning stimulus. A single pulse was applied during shortening or lengthening and peak dynamic (concentric or eccentric) forces were assessed at Lo. Stimulation increased peak concentric force at all frequencies (range: 19±1 to 30 ± 2%) but this increase was proportional to shortening speed, as were the related changes to concentric work/power (range: -15 ± 1 to 39 ± 1 %). In contrast, stimulation did not increase eccentric force, work or power at any frequency. Thus, results reveal a unique hysteresis like effect for the potentiation of dynamic output wherein concentric and eccentric forces increase and decrease, respectively, with work cycle frequency.
    • THE INFLUENCE OF LENGTH CHANGE SPEED AND DIRECTION ON DYNAMIC FUNCTION POTENTIATION IN FAST MOUSE MUSCLE

      Caterini, Daniel; Applied Health Sciences Program (Brock University, 2011-09-09)
      The purpose of this study was to test the hypothesis that the potentiation of dynamic function was dependent upon both length change speed and direction. Mouse EDL was cycled in vitro (25º C) about optimal length (Lo) with constant peak strain (± 2.5% Lo) at 1.5, 3.3 and 6.9 Hz before and after a conditioning stimulus. A single pulse was applied during shortening or lengthening and peak dynamic (concentric or eccentric) forces were assessed at Lo. Stimulation increased peak concentric force at all frequencies (range: 19 ± 1 to 30 ± 2%) but this increase was proportional to shortening speed, as were the related changes to concentric work/power (range: -15 ± 1 to 39 ± 1 %). In contrast, stimulation did not increase eccentric force, work or power at any frequency. Thus, results reveal a unique hysteresis like effect for the potentiation of dynamic output wherein concentric and eccentric forces increase and decrease, respectively, with work cycle frequency.
    • Influence of mitogen-activated protein kinase (MAPK) signaling on mast cell differentiation and histone acetylation modifiers

      Den Hartogh, Danja; Applied Health Sciences Program
      Introduction: Mechanisms directing mast cell differentiation are incompletely defined. Epigenetic modifications by promoter methylation have been identified as key modulators of locus-specific chromatin accessibility during mast cell differentiation, but the role of histone acetylation (HA) has not been explored. Resultant changes in gene accessibility support a trajectory of lineage-specific gene expression as unique cell types mature from pluripotent progenitor hematopoietic stem cells. The MAPK signaling pathway contributes to regulating differentiation and proliferation and directly influences HA modifiers in a host of contexts. We aim to measure how the MAPK signaling pathway influences histone modifiers during mast cell differentiation in vitro toward the identification of potential key contributors. Methods: Mast cell differentiation was initiated from cultures of isolated murine bone marrow and samples were collected throughout differentiation. Quantitative polymerase chain reaction (qPCR) measurement of the RNA level, western blotting assessment of the protein level, and flow cytometry assessment of cell-surface receptor phenotype were conducted for HDACs, HATs and key mast cell-specific markers and transcription factors. Results: The MAPK signaling pathway significantly affected the expression of histone acetyltransferases, histone deacetylases and histone H3 post-translational modification. The inhibition of ERK (SCH772984) differently influenced the differentiation of mast cells through increased HDAC4 and increased PCAF gene expression. This was accompanied with changes in Histone H3 acetylation (K9) and phosphorylation (S10) and increased FcεRIα surface receptor presence with ERK inhibition. The inhibition of p38 (Losmapimod) showed a reduction in mast cell differentiation through decreased mast cell specific transcription factors and enzymes, MITF, Tpsb2, Cpa3 and Cma1, while decreasing FcεRIα receptor presence on the cell surface. The inhibition of JNK (JNK-IN-8) had no effect on mast cell differentiation. Conclusion: This work demonstrates the differential and dynamic importance of the ERK and p38 MAPK signaling pathways in mast cell differentiation and suggests links between the mast cell lineage program and epigenetic modifications via HA. Activation of the p38 MAPK signaling pathway is shown to drive mast cell differentiation, while ERK activation hinders HSC mast cell differentiation.
    • The influence of myosin regulatory light chain phosphorylation on the contractile performance of fatigued mammalian skeletal muscle

      Gittings, William J.; Applied Health Sciences Program (Brock University, 2009-02-16)
      ABSTRACT The myosm regulatory light chain (RLC) of type II fibres is phosphorylated by Ca2+ -calmodulin dependent myosin light chain kinase (skMLCK) during muscular activation. The purpose of this study was to explore the effect of skMLCK gene ablation on the fatigability of mouse skeletal muscles during repetitive stimulation. The absence of myosin RLC phosphorylation in skMLCK knockout muscles attenuated contractile performance without a significant metabolic cost. Twitch force was potentiated to a greater extent in wildtype muscles until peak force had diminished to ~60% of baseline (37.2 ± 0.05% vs. 14.3 ± 0.02%). Despite no difference in peak force (Po) and shortening velocity (Vo), rate of force development (+dP/dt) and shortening-induced deactivation (SID) were almost two-fold greater in WT muscles. The present results demonstrate that myosin RLC phosphorylation may improve contractile performance during fatigue; providing a contractile advantage to working muscles and protecting against progressive fatigue.
    • The influence of physical activity behaviour on the relationship between motor proficiency and body composition in children

      MacInnis, Jennifer.; Applied Health Sciences Program (Brock University, 2008-11-04)
      There is an emerging awareness that children with poor motor abilities are at particular risk for overweight. This cross-sectional study examined the influence of physical activity behaviour on the relationship between motor proficiency and body composition. Participants were 1287 (646 males, 641 females) Grade 6 students in the Physical Health Activity Study project. Height, weight, waist girth, and motor proficiency (Bruininks-Oseretsky Test of Motor Performance BOTMP-SF) were assessed. Physical activity behaviours were also evaluated with a multifaceted approach and reported for school-based, non-school based physical activity, free-time play, and sedentary activities (Participation Questionnaire), and leisure time exercise (Godin-Shephard Leisure Time Exercise Questionnaire GS). Overweight was defined by BMI scores: boys :::20.6-21.2 and <25.1-26.0; girls: ::: 20.7-21.7and <25.4-26.7 and obesity was defined as: boys:::: 25.1-26.0; girls: :::25.4-26.7. Children were classified as case group (CG,::; 10% on BOTMP-SF), borderline case group (BC, > 10% to ::; 20% on BOTMP-SF) or non-case group. Analyses of variance (ANOVAs) uncovered a significant difference in overweight and obesity between the case group and non-case group. Normal-weight children reported higher participation in organized school-sports (intra-mural and inter-school teams). The CG reported significantly lower participation in school sports teams and lower GS results, with a trend towards lower participation in all active pursuits. They also reported a significantly higher duration of television watching and book reading. There were no significant differences between motor proficiency groups by gender, age, nonschool sports, or free-time activity. Multivariate ordinal logistic regression analysis showed that the case group was 10.9 times more likely to be overweight/obese than their peers. No single aspect of physical activity was able to explain the difference in odds ratios for the motor proficiency groups. However, for the entire cohort, children who participated in more organized school sports were less likely to be overweight/obese. These findings confirm that children with low motor proficiency are at significant risk of developing overweight. It is evident that these children have generally attenuated activity levels and heightened levels of sedentary pursuits. School-based activities appear particularly limited, and are the one area where children have near autonomy in their decision to pursue active opportunities. The promotion of school-based programs, specifically intramural sports may be an important aspect in increasing children's overall activity levels. It is also essential to consider the needs of those children with low motor proficiency when designing activity promotion programs. Future research should further explore motor proficiency and overweight/obesity.
    • The influence of physical attractiveness and gender on perceived competence of sportscasters

      Davies, Emma.; Applied Health Sciences Program (Brock University, 2006-05-19)
      The media tends to represent female athletes as women first and athletes second (Koivula, 1 999). The present study investigated whether this same trend was present for female sportscasters, using a self-presentational framework. Self-presentation is the process by which people try to control how others see them (Leary, 1995). One factor that may influence the type of image they try to project is their roles held in society, including gender roles. The gender roles for a man include dominance, assertiveness, and masculinity, while the gender roles for a woman include nurturer, femininity, and attractiveness (Deaux & Major, 1 987). By contrast, sports broadcasters are expected to be knowledgeable, assertive, and competent. Research suggests that female sports broadcasters are seen as less competent and less persuasive than male sports broadcasters (Mitrook & Dorr, 2001; Ordman & Zillmann, 1994, Toro, 2005). One reason for this difference may be that the gender roles for a man are much more similar to those of a sportscaster, compared to those of a woman. Thus, there may be a conflict between the two roles for women. The present study investigated whether the gender and perceived attractiveness of sportscasters influenced the audience's perceptions of the level of competence that a sportscaster demonstrates. Two hundred and four male (n =75) and female (n =129) undergraduate students were recruited from a southern Ontario university to participate in the study. The average age of the male participants was 21 .23 years {SD =1 .60), and the average age for female participants was 20.67 years {SD = 1 .31). The age range for all participants was from 19 to 30 years {M = 20.87 years, SD = 1 .45). Af^er providing informed consent, participants randomly received one of four possible questionnaire packages. The participants answered the demographic questionnaire, and then proceeded to view the picture and read the script of a sports newscast. Next, based on the picture and script, the participants answered the competence questionnaire, assessing the general, sport specific, and overall competence of the sportscaster. Once participants had finished, they returned the package to the researcher and were thanked for their time. Data was analyzed using an ANOVA to determine if general sport competence differs with respect to gender and attractiveness of the sportscaster. Overall, the ANOVA was non-significant (p > .05), indicating no differences on the dependent variable based on gender (F (3, 194) = .631, p = .426), attractiveness (F (3, 194) = .070, p = .791), or the interaction of the two {F (3, 194) = .043,/? = .836). Although none of the study hypotheses were supported, the study provided some insight to the perceived competence of female sportscasters. It is possible that female sportscasters are now seen as competent in the area of sports. Sample characteristics could also have influenced these results; the participants in the current study were primarily physical education and kinesiology students, who had experience participating in physical activity with both men and women. Future research should investigate this issue further by using a video sportscast. It is possible that delivery characteristics such as voice quality or eye contact may also impact perceptions of sportscasters.
    • The influence of recreational ball hockey play on cardiovascular risk factors in sedentary males

      Polesksic, Goran.; Applied Health Sciences Program (Brock University, 2009-02-16)
      Introduction: The prevalence of coronary artery disease (CAD) is ever increasing in western industrialized societies. An individuals overall risk for CAD may be quantified by integrating a number of factors including, but not limited to, cardiorespiratory fitness, body composition, blood lipid profile and blood pressure. It might be expected that interventions aimed at improving any or all of these independent factors might improve an individual 's overall risk. To this end, the influence of standard endurance type exercise on cardiorespiratory fitness, body composition, blood lipids and blood pressure, and by extension the reduction of coronary risk factors, is well documented. On the other hand, interval training (IT) has been shown to provide an extremely powerful stimulus for improving indices of cardiorespiratory function but the influence of this training type on coronary risk factors is unknown. Moreover, the vast majority of studies investigating the effects of IT on fitness have used laboratory type training protocols. As a result of this, the influence of participation in interval-type recreational sports on cardiorespiratory fitness and coronary risk factors is unknown. Aims: The aim of the present study was to evaluate the effectiveness of recreational ball hockey, a sport associated with interval-type activity patterns, on indices of aerobic function and coronary risk factors in sedentary men in the approximate age range of 30 - 60 years. Individual risk factors were compiled into an overall coronary risk factor score using the Framingham Point Scale (FPS). Methods: Twenty-four sedentary males (age range 30 - 60) participated in the study. Subject activity level was assessed apriori using questionnaire responses. All subjects (experimental and control) were assessed to have been inactive and sedentary prior to participation in the study. The experimental group (43 ± 3 years; 90 ± 3 kg) (n = 11) participated in one season of recreational ball hockey (our surrogate for IT). Member of this group played a total of 16 games during an 11 week span. During this time, the control group (43 ± 2 years; 89 ± 2 kg) (n = 11) performed no training and continued with their sedentary lifestyle. Prior to and following the ball hockey season, experimental and control subjects were tested for the following variables: 1) cardiorespiratory fitness (as V02 Max) 2) blood lipid profile 3) body composition 5) waist to hip ratio 6) blood glucose levels and 7) blood pressure. Subject V02 Max was assessed using the Rockport submaximal walking test on an indoor track. To assess body composition we determined body mass ratio (BMI), % body fat, % lean body mass and waist to hip ratio. The blood lipid profile included high density lipoprotein, low density lipoprotein and total cholesterol levels; in addition, the ratio of total cholesterol to high density was calculated. Blood triglycerides were also assessed. All data were analyzed using independent t - tests and all data are expressed as mean ± standard error. Statistical significance was accepted at p :S 0.05. Results: Pre-test values for all variables were similar between the experimental and control group. Moreover, although the intervention used in this study was associated with changes in some variables for subjects in the experimental group, subjects in the control group did not exhibit any changes over the same time period. BODY COMPOSITION: The % body fat of experimental subjects decreased by 4.6 ± 0.5%, from 28.1 ± 2.6 to 26.9 ± 2.5 % while that of the control group was unchanged at 22.7 ± 1.4 and 22.2 ± 1.3 %. However, lean body mass of experimental and control subjects did not change at 64.3 ± 1.3 versus 66.1 ± 1.3 kg and 65.5 ± 0.8 versus 64.7 ± 0.8 kg, respectively. In terms of body mass index and waist to hip ratio, neither the experimental nor the control group showed any significant change. Respective values for the waist to hip ratio and body mass index (pre and post) were as follows: 1 ± 0.1 vs 0.9 ± 0.1 (experimental) and 0.9 ± 0.1 versus 0.9 ± 0.1 (controls) while for BMI they were 29 ± 1.4 versus 29 ± 1.2 (experimental) and 26 ± 0.7 vs. 26 ± 0.7 (controls). CARDIORESPIRATORY FITNESS: In the experimental group, predicted values for absolute V02 Max increased by 10 ± 3% (i.e. 3.3 ± 0.1 to 3.6 ± 0.1 liters min -1 while that of control subjects did not change (3.4 ± 0.2 and 3.4 ± 0.2 liters min-I). In terms of relative values for V02 Max, the experimental group increased by 11 ± 2% (37 ± 1.4 to 41 ± 1.4 ml kg-l min-I) while that of control subjects did not change (41 ± 1.4 and 40 ± 1.4 ml kg-l min-I). BLOOD LIPIDS: Compared to pre-test values, post-test values for HDL were decreased by 14 ± 5 % in the experiment group (from 52.4 ± 4.4 to 45.2 ± 4.3 mg dl-l) while HDL data for the control group was unchanged (49.7 ± 3.6 and 48.3 ± 4.1 mg dl-l, respectively. On the other hand, LDL levels did not change for either the experimental or control group (110.2 ± 10.4 versus 112.3 ± 7.1 mg dl-1 and 106.1 ± 11.3 versus 127 ± 15.1 mg dl-1, respectively). Further, total cholesterol did not change in either the experimental or control group (181.3 ± 8.7 mg dl-1 versus 178.7± 4.9 mg dl-l) and 190.7 ± 12.2 versus 197.1 ± 16.1 mg dl-1, respectively). Similarly, the ratio of TC/HDL did not change for either the experimental or control group (3.8 ± 0.4 versus 4.5 ± 0.5 and 4 ± 0.4 versus 4.2 ± 0.4, respectively). Blood triglyceride levels were also not altered in either the experimental or control group (100.3 ± 19.6 versus 114.8 ± 15.3 mg dl-1 and 140 ± 23.5 versus 137.3 ± 17.9 mg dl-l, respectively). BLOOD GLUCOSE: Fasted blood glucose levels did not change in either the experimental or control group. Pre- and post-values for experimental and control groups were 92.5 ± 4.8 versus 93.3 ± 4.3 mg dl-l and 92.3 ± 11.3 versus 93.2 ± 2.6 mg dl-1 , respectively. BLOOD PRESSURE: No aspect of blood pressure was altered in either the experimental or control group. For example, pre- and post-test systolic blood pressures were 131 ± 2 versus 129 ± 2 mmHg (experimental) and 123 ± 2 and 125 ± 2 mmHg (controls), respectively. Pre- and post-test diastolic blood pressures were 84 ± 2 and 83 ± 2 mmHg (experimental) and 81 ± 1 versus 82 ± 1 mmHg, respectively. Similarly, calculated pulse pressure was not altered in the experimental or control as pre- and post-test values were 47 ± 1 versus 47 ± 2 mmlHg and 42 ± 2 versus 43 ± 2 mmHg, respectively. FRAMINGHAM POINT SCORE: The concerted changes reported above produced an increased risk in the Framingham Point Score for the subjects in the experimental group. For example, the pre- and post-test FPS increased from 1.4 ± 0.9 to 2.7 ± 0.7. On the other hand, pre- and post-test scores for the control group were 1.8 ± 1 versus 1.8 ± 0.9. Conclusions: Our data confirms previous studies showing that interval-type exercise is a useful intervention for increasing aerobic fitness. Moreover, the increase in V02 Max we found in response to limited participation in ball hockey (i.e. 16 games) suggests that recreational sport may help reduce this aspect of coronary risk in previously sedentary individual. On the other hand, our results showing little or no positive change in body composition, blood lipids or blood pressures suggest that one season of recreational sport in not in of itself a powerful enough stimulus to reduce the overall risk of coronary artery disease. In light of this, it is recommended that, in addition to participation in recreational sport, the performance of regular physical activity is used as an adjunct to provide a more powerful overall stimulus for decreasing coronary risk factors. LIMITATIONS: The increase in the FPS we found for the experimental group, indicative of an increased risk for coronary disease, was largely due to the large decrease in HDL we observed after compared to above one season of ball hockey. In light of the fact that cardiorespiratory fitness was increased and % body fat was decreased, as well as the fact that other parameters such as blood pressure showed positive (but non statistically significant) trends, the possibility that the decrease in HDL showed by our data was anomalous should be considered. FUTURE DIRECTIONS: The results of this study suggesting that recreational sport may be a potentially useful intervention in the reduction of CAD require to be corroborated by future studies specifically employing 1) more rigorous assessment of fitness and fitness change and 2) more prolonged or frequent participants.
    • The Influence of Sex on the Relationship Between Arterial Mechanical Properties and Cardiovagal Baroreflex Sensitivity

      Klassen, Stephen; Applied Health Sciences Program
      Cardiovagal baroreflex sensitivity (cvBRS) demonstrates a strong relationship with arterial mechanical properties. Both cvBRS and arterial mechanics differ by sex such that males demonstrate greater cvBRS, yet lower large artery elasticity than females. Whether the relationship between cvBRS and arterial mechanics is similar in males and females remains unexamined. As a result, it is unclear whether arterial mechanics contribute to sex differences in cvBRS. This study investigated the cross-sectional relationship between cvBRS and arterial mechanical properties of the common carotid, carotid sinus and aortic arch (AA) in 36 (18 females) young, healthy normotensives. The cvBRS-arterial mechanics relationship did not reach statistical significance and did not differ by sex. Both cvBRS and AA distensibility were greater in females than males. Sex differences in cvBRS were eliminated after controlling for AA distensibility. These findings suggest that in this sample, AA elasticity may contribute to the greater cvBRS in females than males.
    • The influence of skeletal muscle cell volume on carbohydrate metabolism in contracting skeletal muscle

      Cermak, Naomi.; Applied Health Sciences Program (Brock University, 2006-06-29)
      This study investigated the regulation of carbohydrate metabolism through changes in skeletal muscle cell volume immediately post contraction and during recovery. Using an established in vitro isolated muscle strip model, soleus (SOL) and extensor digitorum longus (EDL) were dissected from male rats and incubated in an organ bath (perfused with 95% O2; 5% CO2, pH 7.4, temperature 25°C) containing medium- 199 altered to a target osmotic condition (iso-, hypo- or hyper-osmotic; 290, 1 80, 400 mmol/kg). Muscles were stimulated for 10 minutes (40 Hz SOL; 30 Hz EDL) and then either immediately flash frozen or allowed to recover for 20 minutes before subsequent metabolite and enzyme analysis. Results demonstrated a relative water decrease in HYPER vs. HYPOosmotic condition (n=8/group; p<0.05) regardless of muscle type. Specifically, the SOL HYPER condition had elevated metabolite concentrations after 10 minutes of stimulation in comparison to both HYPO and ISO (p<0.05), while EDL muscle did not show any significant difTerences between the HYPER or HYPO conditions. After 20 minutes of recovery, metabolic changes occurred in both SOL and EDL with the SOL HYPER condition showing greater relative changes in metabolite concentrations versus HYPO. The results of the current study have demonstrated that osmotic imbalance induces metabolic change within the skeletal muscle cell and muscle type may influence the mechanisms utilized for cell volume regulation.
    • The influence of skeletal muscle cell volume on the regulation of carbohydrate uptake and muscle metabolism

      Farlinger, Christopher M.; Applied Health Sciences Program (Brock University, 2007-06-01)
      This study investigated the regulation of carbohydrate metabolism and glucose uptake through changes in skeletal muscle cell volume. Using an established invitro isolated whole muscle model, soleus (SOL) and extensor digitorum longus (EDL) muscles were dissected from male rats and incubated in an organ bath containing Sigma medium-199 with 8 mM D-glucose altered to target osmolality (hypo-osmotic: HYPO, iso-osmotic: ISO, hyper-osmotic: HYPER; 190, 290, 400 mmol/kg). Muscles were divided into two groups; metabolite (MM) and uptake (MU). MM (N=48) were incubated for 60 minutes and were then immediately flash frozen. MU (N=24) were incubated for 30 minutes and then the extracellular fluid was exchanged for media containing ^H-glucose and ^'*C-mannitol and incubated for another 30 minutes. After the incubation, the muscles were freeze clamped. Results demonstrated a relative water decrease and increase in HYPER and HYPO, respectively. EDL and SOL glucose uptakes were found to be significantly greater in HYPER conditions. The HYPER condition resulted in significant alterations in muscle metabolite concentrations (lower glycogen, elevated lactate, and G-6-P) suggesting a catabolic cell state, and an increase in glycogen synthase transformation when compared to the HYPO group. In conclusion, skeletal muscle cell volume alters rates of glucose uptake with further alterations in muscle metabolites and glycogen synthase transformation.