• The coach-athlete relationship in university female team sports : perceptions of moral agency and ethical considerations

      Lagzdins, Milaina.; Applied Health Sciences Program (Brock University, 2007-05-21)
    • Coaches' use of and impressions of computer-mediated communication (CMC) media /

      Lawrie, Kevin.; Applied Health Sciences Program (Brock University, 2009-06-15)
      The study examined coaches' usage of text-based computer-mediated communication (CMC) media (e.g., text-messaging, email) in the coach-player relationship. Data were collected by surveying Ontario-based male baseball coaches (n = 86) who coached players between 15 and 18 years old. Predictions were made regarding how demographic factors such as age and coaching experience affected coaches' CMC use and opinions. Results indicated that over 76% of respondents never used any CMC media other than email and team websites in their interactions with players. Results also revealed that coaches' usage rates contrasted with their opinion of the usefulness of the media, and their perception of players' use of the media. Coaches characterized most CMC media as limited, unnecessary, and sometimes inappropriate. Additional research should explore players' CMC usage rates and possible guidelines for use of the new media in authority relationships. Academia needs to keep pace with the developments in this area.
    • Comparing motives, goals and weight training behaviours of competitive and recreational weight trainers: An application of organismic integration theory and goal contents theory

      Burns, Matthew; Applied Health Sciences Program (Brock University, 2013-08-23)
      The study purpose was to examine differences between competitive and recreational weight trainers on indices of motivation, goals and behaviour. Data was collected from a purposive sample of competitive (n = 177; Mage = 30.86; SDage = 11.35) and recreational (n = 196; Mage = 21.97; SDage = 6.05) weight trainers using a cross-sectional, non-experimental design. Participants completed the Behavioural Regulation in Exercise Questionnaire-2R, Exercise Motivations Inventory-2, assessment of weight training behaviour and demographic questions. Multivariate analyses of variance indicated higher endorsement of autonomous motives and mostly intrinsically-oriented goals, while independent samples t-tests indicated higher frequency of weight training behaviour among the competitive weight trainers. Group differences were independent of demographic factors. Findings suggest that autonomous motives and intrinsic goals may not be undermined by competition among competitive weight trainers. This study also provides support for the utility of organismic integration theory and goal contents theory in examining strength-based exercise.
    • Comparing the aerobic demand of various pieces of accessible exercise equipment in individuals with multiple sclerosis

      Snyder, Kaitlyn JG; Applied Health Sciences Program
      Current research in the effectiveness of different aerobic exercise modalities for individuals with MS is incomplete. The primary aim of this study is to compare the aerobic response of six selected pieces of accessible exercise equipment at a moderate intensity, as indicated by the current exercise guidelines for individuals with MS. Exercise equipment preference was evaluated using a questionnaire. Participants (n=10) performed a steady-state exercise test on an arm ergometer, arm-leg recumbent stepper, body weight supported treadmill, arm-leg functional electrical stimulation (FES) recumbent stepper, arm FES cycle ergometer, and leg FES cycle. The average VO2 (mlkgmin-1) was recorded on each piece of equipment. Here, the body weight support treadmill, arm leg FES recumbent stepper, and the arm leg stepper were significantly more aerobically demanding than the arm ergometer (p<.05). Further, there were no differences in pain (p> .05), safety (p> .05), enjoyment (p >.05), or anticipated adherence to exercise guidelines in duration (p >.05) or frequency (p> .05). In this study, all forms of accessible aerobic exercise were equally aerobically demanding and preferred in individuals with MS, with the exception of the arm ergometer being less aerobically demanding.
    • Comparison of non-HDL cholesterol and waist circumference vs. triglyceride levels and waist circumference in predicting coronary heart disease risk

      Joshi, Divya.; Applied Health Sciences Program (Brock University, 2009-01-28)
      BACKGROUND: Dyslipidemia is recognized as a major cause of coronary heart disease (CHD). Emerged evidence suggests that the combination of triglycerides (TG) and waist circumference can be used to predict the risk of CHD. However, considering the known limitations of TG, non-high-density lipoprotein (non-HDL = Total cholesterol - HDL cholesterol) cholesterol and waist circumference model may be a better predictor of CHD. PURPOSE: The Framingham Offspring Study data were used to determine if combined non-HDL cholesterol and waist circumference is equivalent to or better than TG and waist circumference (hypertriglyceridemic waist phenotype) in predicting risk of CHD. METHODS: A total of3,196 individuals from Framingham Offspring Study, aged ~ 40 years old, who fasted overnight for ~ 9 hours, and had no missing information on nonHDL cholesterol, TG levels, and waist circumference measurements, were included in the analysis. Receiver Operator Characteristic Curve (ROC) Area Under the Curve (AUC) was used to compare the predictive ability of non-HDL cholesterol and waist circumference and TG and waist circumference. Cox proportional-hazards models were used to examine the association between the joint distributions of non-HDL cholesterol, waist circumference, and non-fatal CHD; TG, waist circumference, and non-fatal CHD; and the joint distribution of non-HDL cholesterol and TG by waist circumference strata, after adjusting for age, gender, smoking, alcohol consumption, diabetes, and hypertension status. RESULTS: The ROC AUC associated with non-HDL cholesterol and waist circumference and TG and waist circumference are 0.6428 (CI: 0.6183, 0.6673) and 0.6299 (CI: 0.6049, 0.6548) respectively. The difference in the ROC AVC is 1.29%. The p-value testing if the difference in the ROC AVCs between the two models is zero is 0.10. There was a strong positive association between non-HDL cholesterol and the risk for non-fatal CHD within each TO levels than that for TO levels within each level of nonHDL cholesterol, especially in individuals with high waist circumference status. CONCLUSION: The results suggest that the model including non-HDL cholesterol and waist circumference may be superior at predicting CHD compared to the model including TO and waist circumference.
    • Comparison of strength gains over 13 and 26-weeks of resistance training in children

      Harris, Alana P. Y.; Applied Health Sciences Program (Brock University, 2009-02-16)
      The primary aim of this study was to determine if there were significant strength gains achieved by children participating in the Hamilton Wentworth District School Board Sport Academy Program. The secondary aim was to determine if the children participating in the 26-week program achieved greater gains or if a plateau in strength adaptations occurred following the 13-week session. The tertiary aim was to determine if there were varying levels of response to the training stimulus between grade 7, grade 8 and grade 9 subjects. Ninety-eight (98) subjects completed a13-week RT program. 6RM strength testing of the chest press, seated row and leg press were conducted prior to the program. Subjects were tested following the 13-week training stimulus to determine if strength gains were achieved and to assess the variation in strength adaptations between the groups. Forty seven (47) subjects completed 26 weeks ofRT. Subjects' strength was tested prior to starting the program, at week 13 of the program and at week 26 of the program to determine the variation in adaptation over a 13 week program versus a 26- week RT program. There were significant (p<O.05) gains across strength measures in the sample following 13 weeks ofRT. Strength adaptations were not significantly (p<O.05) different between groups. The 26-week RT program results showed a significant improvement in all strength measures from pre intervention to 13 weeks. From 13 weeks to 26 weeks grade 8 subjects showed significant gains in both the chest press and seated row exercises while grade 9 subjects showed significant gains across the 6RM seated row, chest press, and leg press measures.
    • Compensatory Arm Reactions in Individuals with Parkinson’s Disease

      Weaver, Tyler; Applied Health Sciences Program (Brock University, 2013-01-14)
      This study examined how perturbation-evoked compensatory arm reactions in individuals with Parkinson’s disease (PD) are influenced by explicit verbal instruction. Ten individuals with PD and 15 older adults without PD responded to surface translations with or without specific instruction to reach for and grasp the handrail. Electromyographic (EMG) and kinematic recordings were taken from the reaching arm. Results showed that individuals with and without PD benefitted similarly from explicit instruction. Explicit instruction resulted in earlier (p=0.005) and larger (p<0.001) medial deltoid EMG responses in comparison to no specific instructions. Compensatory arm reactions also occurred with a higher peak medio-lateral wrist velocity (p<0.001) and higher peak shoulder abduction angular velocity (p<0.001) with explicit instruction. Explicit instruction positively influenced compensatory arm reactions in individuals with and without PD. Future research is needed to determine whether the benefits of instruction persist over time and translate to a loss of balance in real life.
    • Comprehensive school health : an ethnographic case study

      Costas-Bradstreet, Christa.; Applied Health Sciences Program (Brock University, 2009-01-28)
      The purpose of this ethnographic case study was to describe the characteristics of one school's Comprehensive School Health (CSH) initiative and to explore the experiences of school community members in order to gain an understanding of how one school embraced a Comprehensive School Health approach. An elementary school (grades Junior Kindergarten to six) in Burlington, Ontario was the research site for this study. Multiple methods of data collection (observations, document analysis, interviews) were used in keeping with the ethnographic and case study approach. The data were coded using both a deductive and then inductive process (Merriam, 1998). From a deductive perspective, the coding system and the subsequent identification of categories were based on a priori categories identified by using the elements of CSH based on the Comprehensive School Health Consensus Statement prepared by the Canadian Association of School Health and the research questions. Findings included the role that various school community members as well as the implementation of different programs and policies played in applying a CSH approach. The impact ofthe physical environment was described as well as successes and challenges related to the school's experience in implementing CSH. Three main themes emerged that characterized this school's experience. The first theme relates to the fundamental question about CSH which is the school community's understanding o/the concept. The second theme focused on positive school culture and the third and most diverse theme was that of capacity. Engaging in CSH is a complex and long-term undertaking involving both the school and greater community. Based on the experiences of this school's community members, recommendations address the different levels of influence on the health of children.
    • Comprehensive school health, the social determinants of health, and the health status of children

      Spurrell, Julie.; Applied Health Sciences Program (Brock University, 2007-06-29)
      As children are becoming increasingly inactive and obese, there is an urgent need for effective early prevention and intervention programs. One solution is a comprehensive school health (CSH) program, a health promotion initiative aimed at educating students about healthy behaviours and lifestyles, which also provides a link between the school, students, families, and the surrounding community. The purpose of this study was to explore the relationship between different components of CSH programs, as well as three determinants of health (gender, social support, socio-economic status), and physical activity, on the aerobic fitness and body mass index (BMI) of children. A newly developed and pilot-tested survey derived from Health Canada's fourpart CSH model (instruction, social support, support services, and a healthy physical environment) was sent to elementary school principals. Data on the gender, physical activity, parental education, and social support levels of students from these schools were gathered from a previous study. Multiple regression procedures were conducted to estimate the relationships between CSH components, the social determinants of health, physical activity, and BMI and aerobic fitness. Results showed that three CSH components were significantly associated with both BMI and aerobic fitness values in children, but accounted for less than 5% of the variance in both variables. Physical activity partially mediated the relationship between the significant CSH components, BMI, and particularly aerobic fitness. Furthermore, the social determinant and physical activity variables played independent roles in aerobic fitness values. No moderating effects of the social determinants were discovered.
    • A constructivist grounded theory of firefighter perceptions of stress, coping and the relationship to health

      Hunter, Sara B.G.; Applied Health Sciences Program (Brock University, 2005-07-14)
      This qualitative research was a constructivist grounded theory designed to develop an understanding of how firefighters perceive and cope with stressful situations and the impact this has on their perceptions of health. This study was framed in a social ecological perspective with the community of firefighting providing the environment within which to explore stress and coping. Of particular concern here are the stressors associated with firefighting. Prior research with firefighters has often been epidemiological and statistical in nature, focusing on measures of cardiovascular disease, cancer, and depression (Baker & Williams, 2001 ; Brown et al., 2002; Murphy et al.,1999; Regehr et al., 2002; Regehr et al., 2003). Qualitative research examining the perception of stress among firefighters that includes personal stories allows firefighters the opportunity to describe what it is like to be met with physically and mentally challenging situations on a daily basis. Twelve in-depth, semi-structured, face-to-face interviews with a brief questionnaire were conducted with firefighters from a Southern Ontario Fire Department. Four main themes emerged describing the persona of the firefighter, the stressors of firefighters, coping strategies of firefighters, and firefighters' perceptions of health. Stressors include requirements of the job, traumatic calls, tensions with co-workers, the struggle between the family at home and the family at work, political stressors with the City, and the inner struggle. Avoidance coping, approach coping, and gaining perspective emerged as the three coping styles of firefighters. Health was defined as including physical, mental, social and spiritual aspects. A model of the findings is provided that depicts the cyclical nature of the stress-coping-health relationship among firefighters.
    • The Contribution of Nitric Oxide to the Skin Blood Flow Response to Exercise in Boys and Men

      Woloschuk, Alexandra; Applied Health Sciences Program
      In response to heat stress, children sweat less than adults. However, little is known about their skin blood flow (SkBF) response. We investigated child-adult differences in SkBF during exercise (30 min at 60% VO2max) and local heating (44℃) in 12 boys (9.71.2 y) and 12 men (22.22.0 y) using laser-Doppler flowmetry and L-NAME to inhibit nitric oxide (NO). The exercise-induced SkBF increase was greater in boys versus men (p=0.03). L-NAME blunted SkBF response during exercise in boys and men (p<0.01) (758±201 to 429±229 percent change from baseline vs. 541.6±167 to 352±109 percent change from baseline, respectively). Boys had a shorter time delay between the onset of exercise and onset of SkBF response compared with men (p<0.01) and L-NAME increased the time delay in boys and men (205±48 to 268±90 s vs. 309±71 to 376±116 s, respectively) (p=0.01). During local heating, SkBF increases were greater in boys versus men (p<0.01) and L-NAME blunted the SkBF response in boys and men (2594±939 to 1630±791 percent change from baseline vs. 1600±605 to 1046±345 percent change from baseline, respectively) (p<0.01). These data suggest that boys experience greater and faster increases in SkBF during exercise and local skin heating compared with men. NO influence on microvasculature and thermoregulatory function was not different between boys and men.
    • The contribution of skate blade properties to skating speed

      McGurk, Michael; Applied Health Sciences Program
      The purpose of the study was to investigate the relative contribution of skate blade properties to on-ice skating speed. Thirty-two male ice hockey players (mean age = 19±2.65 yrs.) representing the Ontario Minor Hockey Association (OMHA; Midget AAA and Junior), Canadian Inter University Sport (CIS: Varsity), Ontario hockey league (OHL) and East Coast Hockey League (ECHL), and the playing positions of forwards (n=18) and defense (n=14) were recruited to participate. Skate related equipment worn by the players for the purpose of the research was documented and revealed that 80% of the players wore Bauer skates, Tuuk blade holders and LS2 skate blades. Subjects completed a battery of eight on-ice skating drills used to measure and compare two aspects of skating speed; acceleration [T1(s)] and total time to complete each drill [TT(s)] while skating on three skate blade conditions. The drills represented skills used in the game of hockey, both in isolation (e.g., forward skating, backward skating, stops and starts, and cornering) and in sequence to simulate the combination of skills used in a shift of game play. The three blade conditions consisted of (i) baseline, represented by the blades worn by the player throughout their current season of play; (ii) experimental blades (EB), represented by brand name experimental blades with manufacturers radius of contour and a standardized radius of hollow; and (iii) customized experimental blades (CEB), represented by the same brand name experimental blades sharpened to the players’ preference as identified in the baseline condition. No significant differences were found in acceleration time [T1(s)] or total time to complete [TT(s)] the isolated drills across blade conditions; however significant differences were revealed in both T1(s) and TT(s) measured during the execution of the sequenced drill across blade conditions. A iii Bonferroni post hoc test revealed that players skated significantly faster when skating on the CEB condition compared to the baseline condition (p≤.05). A questionnaire assessing subjects perceived comfort, confidence and effort expended while skating on the experimental blades revealed that players were significantly more comfortable when skating on the CEB versus the EB condition (p≤.05). Outcomes of the study provide evidence to suggest that the experimental skate blades customized with the players preferred blade sharpening characteristics results in faster skating speed in a combination drill representing skills performed in gameplay.
    • A critical examination of the involvement of Canadian high-performance athletes in the development of anti-doping policy

      Jackson, Gregory R.; Applied Health Sciences Program (Brock University, 2006-05-21)
      The use of certain perfonnance enhancing substances and methods has been defined as a major ethical breach by parties involved in the governance of highperfonnance sport. As a result, elite athletes worldwide are subject to rules and regulations set out in international and national anti-doping policies. Existing literature on the development of policies such as the World Anti-Doping Code and The Canadian antiDoping Program suggests a sport system in which athletes are rarely meaningfully involved in policy development (Houlihan, 2004a). Additionally, it is suggested that this lack of involvement is reflective of a similar lack of involvement in other areas of governance concerning athletes' lives. The purpose ofthis thesis is to examine the history and current state of athletes' involvement in the anti-doping policy process in Canada's high-perfonnance sport system. It includes discussion and analysis of recently conducted interviews with those involved in the policy process as well as an analysis of relevant documents, including anti-doping policies. The findings demonstrate that Canadian athletes have not been significantly involved in the creation of recently developed antidoping policies and that a re-evaluation of current policies is necessary to more fully recognize the reality of athletes' lives in Canada's high-perfonnance sport system and their rights within that system.
    • A Cross-Sectional Analysis of Functional Movement Screen Scores in Male AAA Minor Hockey Players

      Dol, Steven; Applied Health Sciences Program
      The Functional Movement Screen (FMS) has been used as a screening tool to assess inefficiencies and asymmetries associated with movement patterns that could potentially lead to injury risks in athletic populations (Kiesel, Plisky, & Voight, 2007; Parenteau-G et al., 2014; Mokha et al., 2016). The primary purpose of the study was to compare FMS scores across four hockey-specific chronological age groups and five stages of maturity in adolescent male ice-hockey players. The secondary purpose of the study was to determine if years of experience in a specific sport, correlated with movement pattern asymmetries. One hundred and eleven male (9-17 years) AAA players completed a battery of physical measurements including; height (cm), weight (kg), grip strength (kg), sit and reach (cm) and the FMS. FMS scores were analyzed by total score (TS), FMS subgroups (FMS movement, FMS flexibility and FMS stability), frequencies of individual movement pattern scores and left/right asymmetries. Significant differences in FMS TS were revealed across both chronological age, categorized by hockey age groups (F (3,107) = 7.002), p<.001 and stage of maturity (F (4,106) = 4.790), p<.001, suggesting that FMS TS improved with both age and physical maturity. However, ANCOVA results revealed no significant differences across hockey age groups (F (3,106) =1.917), p=.131, when maturity was entered as a covariate, suggesting that maturity did not influence FMS TS beyond the effect age. FMS sub-groups revealed significant differences in FMS move and FMS stab across both hockey age group and stage of maturity. No significant differences were found in the frequencies of individual screen scores or left/right asymmetries across hockey age groups or stages of maturity. Therefore, the results did not support the assumption of hockey being a significant unilateral training stimulus.
    • Cues to action : do they result in belief and behavioural change in women?

      Gasparotto, Jennifer.; Applied Health Sciences Program (Brock University, 2007-05-21)
      With incidence rates of osteoporosis increasing (Osteoporosis Canada, 2007), preventative efforts to minimize costs associated with condition diagnosis are a public health priority. Cues to action are specific internal (e.g., physical symptoms, family member with a condition) or external stimuli (e.g., public service announcements, health education campaigns) that are necessary to trigger appropriate health behaviours and serve to create an awareness of the health threat (Mattson, 1999). To date, limited understanding of the scope of influence cues to action have on health beliefs and behaviour associated with osteoporosis is known. The present investigation was designed to address this gap in the literature. More specifically, the influence of cues to action, a public service announcement (PSA) developed by Osteoporosis Canada and a bone screening by way of Quantitative Ultrasound, on health beliefs and health-enhancing physical activity (HEPA) across a four week period was investigated. Peri-and postmenopausal women (N= 174) were randomly assigned to one of three conditions 1) an osteoporosis public service announcement (PSA) condition; 2) a bone screening condition via quantitative ultrasound techniques, and 3) a PSA attention control condition. Health beliefs associated with osteoporosis were taken at three time points: prior to the cue to action intervention, immediately following the intervention, and four weeks post intervention. Knowledge of osteorporosis risk factors and HEP A were assessed pre and post-intervention only. Results of a regression analysis suggested that baseline health beliefs predicted baseline HEPA (R2 adj = .24; F (9, 161) = 6.49,p = .000; 95% CI = .12 - .35) with exercise barriers (p = -.33) being a negative predictor and health motivation (p = .21) being a positive predictor of HEP A. Baseline health beliefs predicted With incidence rates of osteoporosis increasing (Osteoporosis Canada, 2007), preventative efforts to minimize costs associated with condition diagnosis are a public health priority. Cues to action are specific internal (e.g., physical symptoms, family member with a condition) or external stimuli (e.g., public service announcements, health education campaigns) that are necessary to trigger appropriate health behaviours and serve to create an awareness of the health threat (Mattson, 1999). To date, limited understanding of the scope of influence cues to action have on health beliefs and behaviour associated with osteoporosis is known. The present investigation was designed to address this gap in the literature. More specifically, the influence of cues to action, a public service announcement (PSA) developed by Osteoporosis Canada and a bone screening by way of Quantitative Ultrasound, on health beliefs and health-enhancing physical activity (HEPA) across a four week period was investigated. Peri-and postmenopausal women (N= 174) were randomly assigned to one of three conditions 1) an osteoporosis public service announcement (PSA) condition; 2) a bone screening condition via quantitative ultrasound techniques, and 3) a PSA attention control condition. Health beliefs associated with osteoporosis were taken at three time points: prior to the cue to action intervention, immediately following the intervention, and four weeks post intervention. Knowledge of osteorporosis risk factors and HEP A were assessed pre and post-intervention only. Results of a regression analysis suggested that baseline health beliefs predicted baseline HEPA (R2 adj = .24; F (9, 161) = 6.49,p = .000; 95% CI = .12 - .35) with exercise barriers (p = -.33) being a negative predictor and health motivation (p = .21) being a positive predictor of HEP A. Baseline health beliefs predicted
    • Decision analysis of the effectiveness of lung cancer screening using autofluorescence bronchoscopy and computed tomography

      Tota, Joseph.; Applied Health Sciences Program (Brock University, 2008-06-15)
      Background: Lung cancer (LC) is the leading cause of cancer death in the developed world. Most cancers are associated with tobacco smoking. A primary hope for reducing lung cancer has been prevention of smoking and successful smoking cessation programs. To date, these programs have not been as successful as anticipated. Objective: The aim of the current study was to evaluate whether lung cancer screening combining low dose computed tomography with autofluorescence bronchoscopy (combined CT & AFB) is superior to CT or AFB screening alone in improving lung cancer specific survival. In addition, the extent of improvement and ideal conditions for combined CT & AFB screening were evaluated. Methods: We applied decision analysis and Monte Carlo simulation modeling using TreeAge Software to evaluate our study aims. Histology- and stage specific probabilities of lung cancer 5-year survival proportions were taken from Surveillance and Epidemiologic End Results (SEER) Registry data. Screeningassociated data was taken from the US NCI Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial (PLCO), National Lung Screening Trial (NLST), and US NCI Lung Screening Study (LSS), other relevant published data and expert opinion. Results: Decision Analysis - Combined CT and AFB was the best approach at Improving 5-year survival (Overall Expected Survival (OES) in the entire screened population was 0.9863) and in lung cancer patients only (Lung Cancer Specific Expected Survival (LOSES) was 0.3256). Combined screening was slightly better than CT screening alone (OES = 0.9859; LCSES = 0.2966), and substantially better than AFB screening alone (OES = 0.9842; LCSES = 0.2124), which was considerably better than no screening (OES = 0.9829; LCSES = 0.1445). Monte Carlo simulation modeling revealed that expected survival in the screened population and lung cancer patients is highest when screened using CT and combined CT and AFB. CT alone and combined screening was substantially better than AFB screening alone or no screening. For LCSES, combined CT and AFB screening is significantly better than CT alone (0.3126 vs. 0.2938, p< 0.0001). Conclusions: Overall, these analyses suggest that combined CT and AFB is slightly better than CT alone at improving lung cancer survival, and both approaches are substantially better than AFB screening alone or no screening.
    • Decreased motor unit firing rate in the potentiated tibialis anterior in humans

      Howard, Jon C.; Applied Health Sciences Program (Brock University, 2009-02-16)
      With repeated activity, force production, rate of force production, and relaxation time are impaired. These are characteristics ofa fatigued muscle (Vandenboom, 2004). However, brief bouts of near maximal to maximal activity results in the increased ability of the muscle to generate force, termed post activation potentiation (P AP)(V andervoort et aI., 1983). The purpose of the present study was to characterize motor unit firing rate (MUFR) in the unfatigued, potentiated tibialis anterior (TA). Using a quadrifilar needle electrode, MUFR was measured during a 5s 50% MVC in which the TA was either potentiated or unpotentiated; monopolar electrodes measured surface parameters. A lOs MVC was used to potentiate the muscle. Firing rate decreased significantly from 20.15±2.9Opps to 18.27±2.99pps, while mean power frequency decreased significantly from 60. 13±7.75 Hz to 53.62±8.56 Hz. No change in root mean square (RMS) was observed. Therefore, in the present study, MUFR decreases in response to a potentiated TA.
    • A denoising algorithm for surface EMG decomposition

      Kumar, Robert; Applied Health Sciences Program
      The goal of the present thesis was to investigate a novel motor unit potential train (MUPT) editing routine, based on decreasing the variability in shape (variance ratio, VR) of the MUP ensemble. Decomposed sEMG data from 20 participants at 60% MVC of wrist flexion was used. There were two levels of denoising (relaxed and strict) criteria for removing discharge times associated with waveforms that did not decrease the VR and increase its signal-to-noise ratio (SNR) of the MUP ensemble. The peak-to-peak amplitude and the duration between the positive and negative peaks for the MUP template were dependent on the level of denoising (p’s <0.05). The error-filtered estimation (EFE) algorithm was used to calculate the inter-discharge interval (IDI) for the denoised MUPTs. In total, VR decreased 24.88% and the SNR increased 6.0% (p’s < 0.05). The standard error of estimate (3.2 versus 3.69%) in mean IDI before and after denoising using the relaxed criteria, was very similar (p>0.05). The same was true between denoising criteria (p>0.05). Editing the MUPT based on MUP shape resulted in significant differences in measures extracted from the MUP template, with trivial difference between the standard error of estimate for mean IDIs between the complete and denoised MUPTs.
    • Determinants of left ventricular mass as measured by Doppler echocardiography in pre-adolescents

      Peralta-Huertas, Jose.; Applied Health Sciences Program (Brock University, 2006-06-04)
      This study examined factors contributing to the differences in left ventricular mass as measured by Doppler echocardiography in children. Fourteen boys (10.3 ± 0.3 years of age) and 1 1 girls (10.5 ± 0.4 years of age) participated in the study. Height and weight were measured, and relative body fat was determined from the measurement of skinfold thickness according to Slaughter et al. (1988). Lean Body Mass was then calculated by subtracting the fat mass from the total body mass. Sexual maturation was self-assessed using the stages of sexual maturation by Tanner (1962). Both pubic hair development and genital (penis or breast for boys and girls respectively) development were used to determine sexual maturation. Carotid Pulse pressure was assessed by applanation tomometry in the left carotid artery. Cardiac mass was measured by Doppler Echocardiography. Images of cardiac structures were taken using B-Mode and were then translated to M- Mode. The dimensions at the end diastole were obtained at the onset of the QRS complex of the electrocardiogram in a plane through a standard position. Measurements included: (a) the diameter of the left ventricle at the end diastole was measured from the septum edge to the endocardium mean border, (b) the posterior wall was measured as the distance from to anterior wall to the epicardium surface, and (c) the interventricular septum was quantified as the distance from the surface of the left ventricle border to the right ventricle septum surface. Systolic time measurements were taken at the peak of the T-wave of the electrocardiogram. Each measurement was taken three to five times before averaging. Average values were used to calculate cardiac mass using the following equation (Deveraux et al. 1986). Weekly physical activity metabolic equivalent was calculated using a standardize activity questionnaire (Godin and Shepard, 1985) and peakV02 was measured on a cycloergometer. There were no significant differences in cardiovascular mesurements between boys and girls. Left ventricular mass was correlated (p<0.05) with size, maturation, peakV02 and physical activity metabolic equivalent. In boys, lean body mass alone explained 36% of the variance in left ventricular mass while weight was the single strongest predictor of left ventricular mass (R =0.80) in girls. Lean body mass, genital developemnt and physical activity metabolic equivalent together explained 46% and 81% in boys and girls, respectively. However, the combination of lean body mass, genital development and peakV02 (ml kgLBM^ min"') explained up to 84% of the variance in left ventricular mass in girls, but added nothing in boys. It is concluded that left ventricular mass was not statistically different between pre-adolescent boys and girls suggesting that hormonal, and therefore, body size changes in adolescence have a main effect on cardiac development and its final outcome. Although body size parameters were the strongest correlates of left ventricular mass in this pre-adolescent group of children, to our knowledge, this is the first study to report that sexual maturation, as well as physical activity and fitness, are also strong associated with left ventricular mass in pre-adolescents, especially young females. Arterial variables, such as systolic blood pressure and carotid pulse pressure, are not strong determinants of left ventricular mass in this pre-adolescent group. In general, these data suggest that although there is no gender differences in the absolute values of left ventricular mass, as children grow, the factors that determine cardiac mass differ between the genders, even in the same pre-adolescent age.
    • Determining If Lowering the Level of Dietary Calcium and Vitamin D in AIN-93G Diet Supports Normal Bone Development and Intestinal Integrity in Female CD-1 Mice

      Yumol, Jenalyn; Applied Health Sciences Program
      Current levels of vitamin D (vit D) and calcium (Ca) in the reference AIN-93G rodent diet may be higher than required for healthy bone structure and bone mineral density (BMD). Other studies suggest that intestinal integrity may be altered by lowering levels of vit D or Ca. The study objective was to determine if lower diet levels of Ca and vit D support development of healthy bone structure and BMD in female CD-1 mice at 2 and 4 months of age without altering intestinal integrity. Lowering the levels of vit D (100 IU/kg) and Ca (3.5 g/kg) did not alter bone structure or BMD. Effects on intestinal integrity are less clear and requires further study using more comprehensive measures. Findings from this study suggest that dietary Ca and/or vit D at current levels in the AIN-93G reference diet may mask potential benefits of nutritional interventions aimed at promoting bone health.