• 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.
    • Neuromuscular adaptations in endurance-trained boys and men

      Cohen, Rotem.; Applied Health Sciences Program (Brock University, 2009-01-28)
      Competitive sports participation in youth is becoming increasingly more common in the Western world. It is widely accepted that sports participation, specifically endurance training, is beneficial for physical, psychomotor, and social development of children. The research on the effect of endurance training in children has focused mainly on healthrelated benefits and physiological adaptations, particularly on maximal oxygen uptake. However, corresponding research on neuromuscular adaptations to endurance training and the latter's possible effects on muscle strength in youth is lacking. In children and adults, resistance training can enhance strength and mcrease muscle activation. However, data on the effect of endurance training on strength and neuromuscular adaptations are limited. While some evidence exists demonstrating increased muscle activation and possibly increased strength in endurance athletes compared with untrained adults, the neuromuscular adaptations to endurance training in children have not been examined. Thus, the purpose of this study was to examine maximal isometric torque and rate of torque development (RID), along with the pattern of muscle activation during elbow and knee flexion and extension in muscle-endurancetrained and untrained men and boys. Subjects included 65 males: untrained boys (n=18), endurance-trained boys (n=12), untrained men (n=20) and endurance-trained men (n=15). Maximal isometric torque and rate of torque development were measured using an isokinetic dynamometer (Biodex III), and neuromuscular activation was assessed using surface electromyography (SEMG). Muscle strength and activation were assessed in the dominant arm and leg, in a cross-balanced fashion during elbow and knee flexion and extension. The main variables included peak torque (T), RTD, rate of muscle activation (Q30), Electro-mechanical delay (EMD), time to peak RTD and co-activation index. Age differences in T, RTD, electro-mechanical delay (EMD) and rate of muscle activation (Q30) were consistently observed in the four contractions tested. Additionally, Q30, nonnalized for peak EMG amplitude, was consistently higher in the endurancetrained men compared with untrained men. Co-activation index was generally low in all contractions. For example, during maximal voluntary isometric knee extension, men were stronger, had higher RTD and Q30, whether absolute or nonnalized values were used. Moreover, boys exhibited longer EMD (64.8 ± 18.5 ms vs. 56.6 ± 15.3 ms, for boys and men respectively) and time to peak RTD (112.4 ± 33.4 ms vs. 100.8 ± 39.1 ms for boys and men, respectively). In addition, endurance-trained men had lower T compared with untrained men, yet they also exhibited significantly higher nonnalized Q30 (1.9 ± 1.2 vs. 1.1 ± 0.7 for endurance-trained men and untrained men, respectively). No training effect was apparent in the boys. In conclusion, the findings demonstrate muscle strength and activation to be lower in children compared with adults, regardless of training status. The higher Q30 of the endurance-trained men suggests neural adaptations, similar to those expected in response to resistance training. The lower peak torque may su9gest a higher relative involvement oftype I muscle fibres in the endurance-trained athletes. Future research is required to better understand the effect of growth and development on muscle strength and activation patterns during dynamic and sub-maximal isometric contractions. Furthennore, training intervention studies could reveal the effects of endurance training during different developmental stages, as well as in different muscle groups.
    • Neuromuscular responses to an isometric force and position task during passive hyperthermia

      Coletta, Nico; Applied Health Sciences Program
      Mechanisms of central nervous system (CNS) impairment during hyperthermia are largely task-dependent. This thesis sought to compare neuromuscular responses of an isometric force and position task during passive hyperthermia, and the relative contributions of rectal (Tre) and skin (T ̅sk) temperature afferents. Surface electromyography (sEMG) was used to assess the electrical activity of the flexor carpi radialis (FCR) muscle during a force and position task. Twenty participants were passively heated from 37.1°C to 39.0°C Tre or thermal tolerance and then cooled back to 37.8°C using a liquid conditioning garment. Passive hyperthermia induced progressive increases in root-mean-square (RMS) amplitude, mean power frequency (MPF) and median power frequency (MDF) for the force task. No change was observed in the sEMG signal for the positon task with passive heating, yet RMS amplitude increased upon skin cooling. Discrepancies in the sEMG signal exist between isometric and dynamic tasks, and these changes are due to core and skin afferents, respectively.
    • Ontario high school sport : an investigation of organizational design and its context

      Sarson, Lindsay A.; Applied Health Sciences Program (Brock University, 2005-05-19)
      In 2002, The Ontario Federation of School Athletic Associations (OFSAA) identified that in providing extracurricular sport programs schools are faced with the 'new realities' of the education system. Although research has been conducted exploring the pressures impacting the provision of extracurricular school sport (Donnelly, Mcloy, Petherick, & Safai, 2000), few studies within the field have focused on understanding extracurricular school sport from an organizational level. The focus of this study was to examine the organizational design (structure, systems, and values) of the extracurricular sport department within three Ontario high schools, as well as to understand the context within which the departments exist. A qualitative multiple case study design was adopted and three public high schools were selected from one district school board in Ontario to represent the cases under investigation. Interviews, observations and documents were used to analyze the extracurricular sport department design of each case and to better understand the context within which the departments exist. As the result of the analysis of the structure, systems and values of each case, two designs emerged- Design KT1 and Design KT2. Differences in the characteristics of design archetype KT1 and KT2 centered on the design dimension of values, and therefore this study identified that contrasting organizational values reflect differences in design types. The characteristics of the Kitchen Table archetype were found to be transferable to the sub-sector of extracurricular school sport, and therefore this research provides a springboard for further research in organizational design within the education sector of extracurricular high school sport. Interconnections were found between the data associated with the external and internal contexts within which the extracurricular sport departments exist. The analysis of the internal context indicated the important role played by organizational members in shaping the context within which the departments exist. The analysis of the external context highlighted the institutional pressures that were present within the education environment. Both political and cultural expectations related to the role of extracurricular sport within schools were visible and were subsequently used by the high schools to create legitimacy and prestige, and to access resources.
    • Organizational commitment and perceived relatedness as correlates of the intention to continue officiating in track and field

      Gray, Casey.; Applied Health Sciences Program (Brock University, 2006-05-19)
      The objectives of the present study were to explore three components of organizational commitment (affective [AC], normative [NC] and continuance [CC] commitment; Allen & Meyer, 1991), perceived relatedness (Oeci & Ryan, 1985; 2002), and behavioural intention (Ajzen, 2002) within the context of volunteer track and field officiating. The objectives were examined in a 2-phase study. Ouring phase 1, experts (N = 10) with domain familiarity assessed the item content relevance and representation of modified organizational commitment (OC; Meyer, Allen & Smith, 1993) and perceived relatedness (La Guardia, Oeci, Ryan & Couchman, 2000) items. Fourteen of 26 (p < .05) items were relevant (Aiken's coefficient V) and NC (M = 3.88, SO = .64), CC (M = 3.63, SD = .52), and relatedness (M = 4.00, SD = .93) items had mean item content-representation ratings of either "good" or "very good" while AC (M = 2.50, SD = 0.58) was rated "fair". Participants in phase 2 (N = 80) responded to items measuring demographic variables, perceptions of OC to Athletics Canada, perceived relatedness to other track and field officials, and a measure of intention (yiu, Au & Tang, 2001) to continue officiating. Internal consistency reliability estimates (Cronbach's (1951) coefficient alpha) were as follows: (a) AC = .78, (b) CC = .85, (c) NC = .80 (d) perceived relatedness = .70 and, (e) intention = .92 in the present sample. Results suggest that the track and field officials felt only minimally committed to Athletics Canada (AC M = 3.90, SD = 1.23; NC M = 2.47, SD = 1.25; CC M = 3.32; SD = 1.34) and that their relationships with other track and field officials were strongly endorsed (M = 5.86, SD = 0.74). Bivariate correlations (Pearson r) indicated that perceived relatedness to other track and field officials demonstrated the strongest relationship with intention to continue officiating (r = .346, p < .05), while dimensions of OC were not significantly related to intention (all p's > .05). Together perceived relatedness (j3 = .339, p = .004), affective commitment (j3 = -.1 53, p = .308), normative commitment (j3 = -.024, p = .864) and continuance commitment (j3 = .186, P = .287) contribute to the prediction of intention to continued officiating (K = .139). These relationships remained unaffected by the inclusion of demographic (j3age = -.02; P years with Athletics Canada = -.13; bothp's > .05) or alternative commitment (j3sport = -.19; P role = .15; Pathletes = .20; all p' s > .05) considerations. Three open-ended questions elicited qualitative responses regarding participants' reasons for officiating. Responses reflecting initial reasons for officiating formed these higher order themes: convenience, helping reasons, extension of role, and intrinsic reasons. Responses reflecting reasons for continuing to officiate formed these higher order themes: track and field, to help, and personal benefits. Responses reflecting changes that would influence continued involvement were: political, organizational/structural, and personal. These results corroborate the findings of previous investigations which state that the reasons underpinning volunteer motivations change over time (Cuskelly et al., 2002). Overall, the results of this study suggest that track and field officials feel minimal commitment to the organization of Athletics Canada but a stronger bond with their fellow officials. Moreover, the degree to which track and field officials feel meaningfully connected to one another appears to exert a positive influence on their intentions to continue officiating. As such, it is suggested that in order to promote continued involvement, Athletics Canada increases its focus on fostering environments promoting positive interactions among officials.
    • The perception of mental toughness of student-athletes in their academic and sports domains

      Waters, Liam; Applied Health Sciences Program
      The purpose of this study was to investigate university student-athletes’ perceptions of mental toughness in both their sport and academic domains. This study took a general qualitative approach through a constructivist lens, to allow for student-athletes’ perceptions to shape the understanding of mental toughness. There were a total of 10 participants (3 male and 7 female student-athletes) interviewed from a variety of sports and academics programs. Thematic analysis was used to identify four main themes: the dynamic nature of mental toughness, outcomes of mental toughness, resilience, and relationships. Findings highlighted similarities and differences between sports and academics, that allow for a better understanding of mental toughness in general, specifically amongst this demographic. The theme “The dynamic nature of mental toughness” showed that mental toughness fluctuated within different environmental settings or with varying performance outcomes, but in general it improved over time. Outcomes of mental toughness refer to factors such as confidence that resulted when participants experienced high levels of mental toughness, and also included the pursuit and embrace of a challenge to compete at peak performance, staying consistent, and staying focused on the task. Resilience was mutually understood as an essential characteristic of mental toughness within both sports and academics, and was more pronounced amongst student-athletes when their mental toughness state was high. The theme of relationships was a unique finding that showed how personal and professional relationships contribute to mental toughness differently within sports compared to academics. Forming a personal relationship with a teammate/classmate outside of the direct sport/academic setting helped athletes with their mental toughness. Additionally, it helped form a stronger professional relationship within the respective domains as well, aiding their performance. Across all themes, mental toughness was more prominent in sports than academics, where student-athletes generally described mental toughness as playing a crucial role in their academics. In addition, results showed support for the unidimensional nature of mental toughness through its general applicability described by participants in both domains without restriction of different dimensions. Therefore, the findings of this study indicate that mental toughness is a crucial psychological resource for student-athletes within both sports and academics.
    • Personality traits and individual differences predict changes in postural control under conditions of height-induced postural threat

      Zaback, Martin; Applied Health Sciences Program (Brock University, 2014-09-05)
      This thesis explored whether individual characteristics could predict changes in postural control in young adults under conditions of height-induced postural threat. Eighty-two young adults completed questionnaires to assess trait anxiety, trait movement reinvestment, physical risk-taking, and previous experience with height-related activities. Tests of static (quiet standing) and anticipatory (rise to toes) postural control were completed under conditions of low and high postural threat manipulated through changes in surface height. Individual characteristics were able to significantly predict changes in static, but not anticipatory postural control. Trait movement reinvestment and physical risk-taking were the most influential predictors. Evidence was provided that changes in fear and physiological arousal mediated the relationship between physical risk-taking and changes in static postural control. These results suggest that individual characteristics shape the postural strategy employed under threatening conditions and may be important for clinicians to consider during balance assessment and treatment protocols.