• A qualitative case study of the processes of peer education in a young adult tobacco control initiative, Leave the Pack Behind

      Gartner, Tiffany.; Applied Health Sciences Program (Brock University, 2007-05-21)
      Peer education involves peers offering credible and reliable information about sensitive life issues through the means of an informal peer group setting (Topping & Ehly, 1998). The purpose of this instrumental case study was to examine the processes of peer education through the exploration of two teams within a young adult tobacco control initiative, Leave the Pack Behind (LTPB). This qualitative case study examined two peer education teams over an eight-month period. Interviews, focus groups and observations were conducted with 12 participants across two peer education teams. Findings show the complexities of the processes of peer education including a connection between the stages of change and the changing role of the peer educator across stages of the empowerment process. Peer education teams and factors in the macro environment were also found to impact the process of peer education. This study provides a new definition for the process of peer education: peer education is a fluid process of knowledge exchange in which peer educators adopt different styles of facilitation as people move through stages of empowerment and change. This study contributes to the academic hterature upon the processes of peer education by providing a definition, a model and an overall understanding through an ecological and empowerment framework. The findings from this study suggest peer educators can be further trained to: use specific peer educational approaches that fit with student smoker's stage of change; better understand their position as a peer educator on the LTPB team; understand the reciprocal relationship between the macro environment and the peer education teams having an effect on one another.
    • A qualitative narrative inquiry of the experience of accessing community supports among women who have experienced trauma

      Akseer, Riaz.; Applied Health Sciences Program (Brock University, 2008-05-21)
      Abuse related trauma can have serious consequences on individuals' health and their state of well-being and may result in decreased access to different determinants of health. The purpose of this qualitative narrative inquiry using secondary data was to explore the experience of accessing community supports among eight women who had experienced abuse-related trauma. A conceptual framework drawn from the literature on social inclusion and social exclusion and a narrative inquiry method were used to explore epiphanies, customs, routines, images, and everyday experiences (Clandinin & Connelly, 2000) among the women. A Three-Dimensional Space Narrative Structure was used to explore the participants' personal or internal conditions, feelings, hopes and reaction as well as their social experiences in interaction with others in community. The participants described experiencing the impact of trauma in their past and present circumstances, a lack of accommodation of difference, challenges in maintaining a sense of self in a world of assumption and labels, impact of trauma on the determinants of health, and uncertainty about the future. The findings from the study demonstrate experiences of social exclusion among the participants in the past, further isolation and social exclusion in the present when personal life issues were ignored by community support services, and uncertainty about what the future will bring for them. The findings indicate close relationships between the women's personal lives and their social connections which need to be considered to mitigate social exclusion and enhance social inclusion.
    • A qualitative study of inclusion at a residential summer camp

      Mecke, Tricia.; Applied Health Sciences Program (Brock University, 2003-07-14)
      The purpose of this qualitative case study was to understand the inclusion process at a Project Rainbow affiliated camp. Project Rainbow is a non-profit organization which promotes inclusion into children's camps in Ontario. This study was completed in order to provide stakeholders of the camping industry insight on how inclusive techniques can be implemented in residential camps. The researcher observed one camp's inclusion techniques for six days. The researcher observed three campers with disabilities and the camp staff and campers that interacted with them on a daily basis. While the researcher was at the camp, she interviewed nine staff members. The staff members consisted of the camp director, the inclusion coordinator, four camp counsellors, and three inclusion counsellors. An additional interview was conducted after arriving home from camp with the manager from Project Rainbow. The qualitative analysis program NVivo was used to help organize the analyzed data. The researcher found that in attempting to build a culture of inclusion, two important concepts are necessary. First, mutual leadership involved the camp director and Project Rainbow working together as a team to facilitate the inclusion process. Second, power of supportive relationships focused on inclusion being the responsibility of everyone, teamwork, and creating a welcoming environment. Hints at some potentially serious problems related to staff training, teamwork, and attitudes of non-disabled campers pointed to future research and policies which focus on the Ontario and Canadian Camping Associations' role in inclusion, in addition to camp in this study and Project Rainbow.
    • Quantifying the Relationship of Bilateral Blood Flow in Glabrous Skin at Rest and During Sympathetic Perturbations

      McNabb, Leed; Applied Health Sciences Program
      Sympathetic nervous system regulation of blood flow within glabrous skin occurs through control of vasoconstrictor tone, with vasodilation being a passive process. As bursts of sympathetic vasoconstrictor activity occur simultaneously at separate sites of the body, blood flow patterns should also be closely matched due to the direct connection between sympathetic nerves and peripheral microvessels. With sympathetic activity difficult and invasive to measure directly, the possibility of using blood conductance as an indirect measure seems promising. We investigated the relationship of bilateral blood conductance recordings of both middle fingers in ten (7M, 3F) healthy participants, while at rest and in response to perturbations known to elicit sympathetic activity. Cutaneous vascular conductance was measured from both middle fingers via laser Doppler flowmetry, while at rest in a thermoneutral room for 20 minutes and in response to 4 randomized sympathetic perturbations (2 breath holds and 2 cold stimuli) while centrally vasodilated via heating of the back. Correlation coefficients while at thermoneutral rest were high (0.80 ± 0.22) demonstrating a strong temporal relationship for blood conductance in both fingers. During the sympathetic perturbations, blood conductance in both fingers were more related during (0.93 ± 0.11) and post (0.87 ± 0.11) administration of the sympathetic perturbation than prior (0.67 ± 0.25) to the administration (p = 0.002). Taken together, these findings indicate that blood conductance patterns at separate sites of the body are significantly more related during vasoconstrictor activity and that blood conductance may have potential as a non-invasive measure of sympathetic activity.
    • Reactive stepping strategies following lateral surface translations in individuals with a unilateral lower limb amputation

      Ferguson, Oran; Applied Health Sciences Program
      Following a loss of balance, individuals may utilize specific stepping strategies to prevent themselves from falling. The stepping strategies that are used by lower limb amputees, which likely consist of unique properties because of the limitations when using a prosthesis, have not been thoroughly identified. Therefore, this study examined the lateral reactive stepping strategies used eight amputees and ten non-amputees. They experienced four support-surface translations in both the leftward and rightward direction. Results indicated that amputees use unique reactive stepping strategies, particularly with the unloaded leg and when the direction of the perturbation causes unloading of the prosthesis. Amputee stepping strategies were characterized by fewer steps, lower quality of balance recovery, and wider variety compared to non-amputees. This study's findings highlight the reliance on the hip strategy in amputee reactive balance, and future studies should explore how amputees use their hip and trunk while executing reactive stepping strategies.
    • Redefining Exhaustion: Considerations for the Modeling of Critical Power

      Steele, Scott; Applied Health Sciences Program
      Background: The relationship between exercise intensity and the limit of tolerance is the focus of the Critical Power (CP) model. CP defines the upper limit for which exercise is steady state and is – in theory – indefinitely sustainable. However, this limit of tolerance at CP is often well below 30 min. Purpose: We want to test the hypothesis that 1) a clinically significant residual W’ capacity (W’res) does exist, 2) that the size of W’res is inversely related to tlim used in the testing protocols, and 3) that accounting for W’res will result in an improved calculation of the Critical Power (CP), as determined by an increased time to exhaustion at CP. Methods: Nine well-trained cyclists performed a ramp test and four high-intensity tests to exhaustion on a cycle ergometer to determine CP and the curvature constant (W’). Two tests to exhaustion were then performed at the traditional CP (CPtrad) and a novel, modified CP (CPmod) to test the practical significance of the residual capacity on the calculation of the CP. Results: All participants were able to perform work above CP even after reaching the limit of tolerance, despite no significant changes in physiological parameters. Including the W’res resulted in significantly lower estimations of CP (TRAD: 281W, MOD: 278 W; p = 0.015) and higher estimations of W’ (TRAD: 15.8 kJ, MOD: 17.8 kJ; p = 0.008). Significance: Athletes were able to continue generating power above CP, even after reaching the limit of tolerance. This residual capacity resulted in a significantly lower estimate of CP and significantly higher estimation of W’.
    • Reduced power output in skeletal muscles devoid of skMLCK: RLC phosphorylation contributes to peak performance

      Bowslaugh, Joshua; Applied Health Sciences Program
      Regulatory light chain (RLC) phosphorylation in fast twitch muscle is catalyzed by skeletal myosin light chain kinase (skMLCK), a reaction known to increase muscle force, work, and power. The purpose of this study was to explore the contribution of RLC phosphorylation on the power of mouse fast muscle during high frequency (100 Hz) concentric contractions. To determine peak power shortening ramps (1.05 to 0.90 Lo) were applied to Wildtype (WT) and skMLCK knockout (skMLCK-/-) EDL muscles at a range of shortening velocities between 0.05-0.65 of maximal shortening velocity (Vmax), before and after a conditioning stimulus (CS). As a result, mean power was increased to 1.28 ± 0.05 and 1.11 ± .05 of pre-CS values, when collapsed for shortening velocity in WT and skMLCK-/-, respectively (n = 10). In addition, fitting each data set to a second order polynomial revealed that WT mice had significantly higher peak power output (27.67 ± 1.12 W/ kg-1) than skMLCK-/- (25.97 ± 1.02 W/ kg-1), (p < .05). No significant differences in optimal velocity for peak power were found between conditions and genotypes (p > .05). Analysis with Urea Glycerol PAGE determined that RLC phosphate content had been elevated in WT muscles from 8 to 63 % while minimal changes were observed in skMLCK-/- muscles: 3 and 8 %, respectively. Therefore, the lack of stimulation induced increase in RLC phosphate content resulted in a ~40 % smaller enhancement of mean power in skMLCK-/-. The increase in power output in WT mice suggests that RLC phosphorylation is a major potentiating component required for achieving peak muscle performance during brief high frequency concentric contractions.
    • Regulation of Protein Turnover during Hyper-osmotic Stress in Skeletal Muscle

      Vandommele, Cody; Applied Health Sciences Program (Brock University, 2013-02-12)
      The purpose of this study was to examine the effect of hyper-osmotic stress on protein turnover in skeletal muscle tissue using an established in-vitro model. Rat EDL muscles were incubated in either hyper-osmotic (400 ± 10 Osm) or isoosmotic (290 ± 10 Osm) custom-modified media (Gibco). L-[14C]-U-phenylalanine (n=8) and cycloheximide (n=8) were used to quantify protein synthesis and degradation, respectively. Western blotting analyses was performed to determine the activation of protein synthesis and degradation pathways. During hyperosmotic stress, protein degradation increased (p<0.05), while protein synthesis was decreased (p<0.05) as compared to the iso-osmotic condition. The decline in protein synthesis was accompanied by a decrease (p<0.05) in p70s6 kinase phosphorylation, while the increase in protein degradation was associated with an increase (p<0.05) in autolyzed calpain. Therefore, hyper-osmotic extracellular stress results in an intracellular catabolic environment in mammalian skeletal muscle tissue.
    • Relationship between adverse childhood experiences and arterial stiffness over time from childhood into early adulthood

      Rafiq, Talha; Applied Health Sciences Program
      It is well established in the literature that there is an association among adults between adverse childhood experiences (ACEs) and arterial stiffness, and between arterial stiffness and cardiovascular disease. However, recent cross-sectional evidence suggests that ACEs may play an important role in the development and progression of arterial stiffness, but it remains unclear when these changes begin to manifest. Therefore, the purpose of this research was to examine the relationship between ACEs and arterial stiffness from childhood into adulthood using population-based longitudinal data. A total of 76 young adults (females = 44), with an average age of 21 years (SD = 1) were included in this study. Overall, a total of 71 respondents reported to have experienced at least one ACE. The findings of this study showed ACEs-exposed individuals have a greater increase in arterial stiffness over time from childhood into young adulthood. This increase was similar for both males and females. Also, differences in heart rate, systolic blood pressure, body mass index, and physical activity did not mediate the relationship between ACEs and arterial stiffness over time. It is therefore important to recognize individuals with exposure to ACEs early on in life in an effort to lower the risk of arterial stiffness and in turn the cascade of events leading to cardiovascular disease.
    • The relationship between adverse childhood experiences and pro-inflammatory analytes and the mediating role of cortisol

      Wong, Kingston; Applied Health Sciences Program
      Adverse childhood experiences (ACEs) are harmful experiences that have occurred during the developing years of life. ACEs often include maltreatment, household dysfunctions and other traumatic events. People with ACEs have been found to be at greater risk of pulmonary, cardiovascular and auto-immune diseases. Recent research has suggested that the epigenetic regulation occurring as a result of these ACEs can program macrophages to sustain inflammatory processes and therefore contribute to the development of these diseases. As one of the primary responders to stress, cortisol is also a suppressor of inflammation. Therefore, dysregulation of the cortisol levels, chronically high or low, also brought forth by ACEs exposure can affect inflammation. The purpose of the current study was to investigate the relationship between ACEs exposure and physiological measures including cortisol and different pro-inflammatory analytes. This cross-sectional study included follow-up data from 156 participants as part of the Niagara Longitudinal Heart Study. Out of the 156 participants, a final sample of 101, with 23 males and 78 females, complete with physiological measures was included in the analyses. The current study collected ACEs data from questionnaire, cortisol from hair, and inflammatory analytes including CRP, IL-6Rα, gp130, sTNFr1, sTNFr2, IFN-γ, and IL-10 from blood. Total ACEs score was negatively associated with cortisol levels. Every additional exposure to a type of ACEs decreased cortisol levels by 21.2 (pg/mg) on average. Exposure to ACEs was positively associated with IL-6Rα but was not associated with all other inflammatory analytes. Every additional exposure to a type of ACEs increased IL-6Rα levels by 284.6 (pg/mL) on average. In contrast to previous literature, sex differences from the regression analyses were also found in the current study among the inflammatory analytes CRP, IL-6Rα, sTNFr1, and IL-10. Cortisol did not mediate the relationship between exposure to ACEs and the different inflammatory analytes. The current study was limited in properly detecting associations as the pilot sample was underpowered. The proportion of cortisol availability in males was much lower than in females. The current study found that ACEs were associated with lowered chronic cortisol and elevated IL-6Rα.
    • The relationship between body mass index and breast cancer recurrence/progression and breast cancer-specific death

      Tosevski, Cedomir; Applied Health Sciences Program (Brock University, 2011-03-08)
      The aim of this study was to describe the nonlinear association between body mass index (BMI) and breast cancer outcomes and to determine whether BMI improves prediction of outcomes. A cohort of906 breast cancer patients diagnosed at Henry Ford Health System, Detroit (1985-1990) were studied. The median follow-up was 10 years. Multivariate logistic regression was used to model breast cancer recurrence/progression and breast cancer-specific death. Restricted cubic splines were used to model nonlinear effects. Receiver operator characteristic areas under the curves (ROC AUC) were used to evaluate prediction. BMI was nonlinearly associated with recurrence/progression and death (p= 0.0230 and 0.0101). Probability of outcomes increased with increase or decrease ofBMI away from 25. BMI splines were suggestive of improved prediction of death. The ROC AUCs for nested models with and without BMI were 0.8424 and 0.8331 (p= 0.08). I f causally associated, modifying patients BMI towards 25 may improve outcomes.
    • Relationship between physical activity and resting secretory immunity in children

      Cieslak, Thomas J.; Applied Health Sciences Program (Brock University, 2002-05-21)
      This study examined relationships among physical activity, body fat and salivary immonoglobulin A (sIgA) levels in adolescent children of Southern Ontario. Gender differences on these factors were also assessed. Sixty-one grade-five students (10-1 lyrs), males (n=29) and females (n=31), who had not received a flu vaccination in the past 12 months, participated in the study. They were assessed for: aerobic power (20-m shuttle run), relative body fat (bioelectrical impedance analysis), sIgA, sIgA/albumin ratio, and salivary Cortisol. Each subject completed the Habitual Activity Estimation Scale and the Participation Questioimaire. Students wore a pedometer for 48h to estimate their average total distance traveled per day. The results show 40% of the children were over 25% body fat and 50% of them spend less than five hours per day in any physical activities. Salivary IgA was not related to salivary Cortisol, physical activity, fitness level or body fat in this age group. There were no gender differences in sIgA and Cortisol levels. Boys had a significantly higher aerobic power and daily distance traveled, but reported similar organized and fi-ee time activity participation levels as the girls. The test-retest reproducibility for salivary Cortisol was 0.663 (p<0.01), while long term sIgA and sIgA/albumin ratio reproducibility was non-significant for repeated measurements taken after six weeks. It was found that salivary IgA has not been shovm to be a stable measure in children, in contrast to the results found in the literatiu-e that tested adults and the relationship with physical activity, fitness level and body fat.
    • Relationship between Socio-Demographic Factors and Familial and Partner Pressures to Conceive in HIV-Positive Women in Ontario

      Mehta, Sachin; Applied Health Sciences Program (Brock University, 2014-07-28)
      This study examined the relationship between socio-demographic factors and family and partner pressure to conceive in women living with HIV in Ontario, Canada. A total of 490 women, aged 18-52 years were included in the study. The HIV Pregnancy Planning Questionnaire was used to collect data on socio-demographic, medical, and pressure variables. Multivariate logistic regression analysis suggest that increased age, years lived in Canada, and living in Toronto were associated with lower odds, and being married and having 0-1 lifetime births were associated with higher odds of family pressure to conceive. Increased age was associated with lower odds, and being married and living in Toronto were associated with higher odds of partner pressure to conceive. Findings suggest that socio-demographic factors influence the fertility decision-making process. Health care providers should consider socio-demographic factors along with medical factors when assisting women living with HIV and their partners to make informed reproductive decisions.
    • The relationship between socioeconomic status, schools and bone health among adolescent females in Southern Ontario

      Imam, Sabrina; Applied Health Sciences Program (Brock University, 2013-09-11)
      We studied the association between socioeconomic status (SES), school attended and bone health measured by bone speed of sound (SOS) among adolescent females in Canada. 412 participants from six randomly selected schools in Southern Ontario were examined. Bone SOS was measured by quantitative ultrasound. Participant’s school and aggregate area-based census-derived (AABCD) SES were evaluated as predictors. Mean participant age was 15.7 (SD 1.0) years. Average median family income was $68,162 (SD $19,366). Median family income was non-linearly associated with bone SOS and restricted cubic splines described the relationship. Univariate regression, accounting for clustering of participants in schools, revealed a significant non-linear association between AABCD-median family income and non-dominant tibial SOS (LRT p = 0.031). Multivariable regression revealed school to have a significant impact (LRT p = 0.0001). High schools had a strong influence on the bone health of female students and this effect overrode the effect of SES.
    • Relationship between Surface and Indwelling EMG Spike Shape Measures

      Parro, Justin; Applied Health Sciences Program (Brock University, 2014-09-04)
      Indwelling electromyography (EMG) has great diagnostic value but its invasive and often painful characteristics make it inappropriate for monitoring human movement. Spike shape analysis of the surface electromyographic signal responds to the call for non-invasive EMG measures for monitoring human movement and detecting neuromuscular disorders. The present study analyzed the relationship between surface and indwelling EMG interference patterns. Twenty four males and twenty four females performed three isometric dorsiflexion contractions at five force levels from 20% to maximal force. The amplitude measures increased differently between electrode types, attributed to the electrode sensitivity. The frequency measures were different between traditional and spike shape measures due to different noise rejection criteria. These measures were also different between surface and indwelling EMG due to the low-pass tissue filtering effect. The spike shape measures, thought to collectively function as a means to differentiate between motor unit characteristics, changed independent of one another.
    • The Relative Age Effect in Minor Ice Hockey: Investigating the 'Underdog Effect'

      Belgiorgio, Matthew; Applied Health Sciences Program (Brock University, 2014-09-05)
      Abstract The Relative Age Effect (RAE), defined as a skewed birth date distribution, has been identified as a known phenomenon in minor ice hockey. The purpose of this study was to investigate the relationship between the RAE, physical measurements, and skating ability/in-game performance in forty-four youth male ice hockey players competing in the same age cohort. Physical anthropometrics, grip strength, in-game performance and skating abilities were measured. An RAE was found in the sample (χ2(3, N = 44) = 12.18, p = 0.007). Players born in the first half of the age cohort had longer leg length (F(1,42) =4.49 , p = 0.04), larger body mass (F(1,42) = 3.90, p = 0.05), and stronger grip strength (F(1,42) = 7.58, p = 0.009). Performance scores were negatively associated with grip strength (r = -.443, p = 0.003). Findings suggest that adequate skill development can help relatively younger players overcome physical maturity disadvantages.
    • Relative importance of body composition, osteoporosis- related behaviours and socioeconomic status on bone SOS in adolescent females

      Holmes, Brianna Lynn.; Applied Health Sciences Program (Brock University, 2009-02-16)
      The purpose of this study was to examine the associations between bone speed of sound (SOS) and body composition, osteoporosis-related health behaviours, and socioeconomic status (SES) in adolescent females. A total of 442 adolescent females in grades 9-11 participated. Anthropometric measures of height, body mass, and percent body fat were taken, and osteo-protective behaviours such as oral contraceptive use (OC), physical activity and daily calcium intake were evaluated using self-report questionnaires. Bone SOS was measured by transaxial quantitative ultrasound (QUS) at the distal radius and mid-tibia. The results suggest that fat mass is a significant negative predictor of tibial SOS, while lean mass is positively associated with radial SOS scores and calcium intake was positively associated with tibial SOS scores (p<O.05). Additionally, users of OC had higher radial SOS. No significant correlation was found between physical activity and bone SOS. Therefore bone strength measured by QUS is reduced in adolescents with an increased fat mass, and influenced positively by OC use, calcium intake and lean mass.
    • Reliability Generalization: Exploring Score Reliability Variance with Ryff’s Scale of Psychological Well-Being

      Crouch, Meghan; Applied Health Sciences Program
      The purpose of this study was to conduct a Reliability Generalization (RG; Vacha-Haase, 1998) for Ryff’s Scale of Psychological Well-Being (PWB; Ryff, 1989) to characterize the average score reliability, the variability of the score reliability, and explore possible sample and test characteristics that influenced score reliability across studies. Studies were included in the current investigation if they had been published in a peer-reviewed journal, used one or more subscales of the Ryff’s PWB, estimated coefficient alpha value(s) for the PWB subscale(s) used, and were written in English. Out of the 924 articles generated by the search strategy, a total of 264 articles were included in the final sample for meta-analysis. The average coefficient alpha for the composite PWB scale was 0.858, with mean coefficient alphas ranging from 0.722 for the Autonomy subscale to 0.801 for the Self-Acceptance subscale. Statistically significant heterogeneity was present across all mean coefficient alphas (p < .05), with the heterogeneity index above 95% for both composite and subscale alphas. Consequently, select sample and test characteristics of the primary studies were explored as possible moderator variables on coefficient alpha estimates, with significant differences in score reliability estimates across select demographic and test characteristics. Test length accounted for the majority of variance among alpha coefficients with R2 values ranging from 40% on the Environmental Mastery subscale to 71% on the Self-Acceptance subscales across the primary studies. In light of the current findings, implications for researchers using Ryff’s PWB including informed score reliability reporting practices are discussed.
    • Reliability of a new measure of motoneuron excitability

      Christie, Anita.; Applied Health Sciences Program (Brock University, 2003-07-09)
      Objectlve:--This study examined the intraclass reliability· of different measures of the excitability of the Hoffmann reflex, derived from stimulus-response curves. The slope of the regression line of the H-reflex stimulus-response curve advocated by Funase et al. (1994) was also compared to the peak of the first derivative of the H-reflex stimulus-response curve (dHIdVmax), a new measure introduced in this investigation. A secondary purpose was to explore the possibility of mood as a covariate when measuring excitability of the H-reflex arc. Methods: The H-reflex amplitude at a stimulus intensity corresponding to 5% of the maximum M-wave (Mmax) is an established measure that was used as an additional basis of comparison. The H-reflex was elicited in the soleus for 24 subjects (12 males and 12 females) on five separate days. Vibration was applied to the Achilles tendon prior to stimulation to test the sensitivity of the measures on test day four. The means of five evoked potentials at each gradually increasing intensity, from below H-reflex threshold to above Mmax, were used to create both the H-reflex and M-wave stimulus response curves for each subject across test days. The mood of the subjects was assessed using the Subjective Exercise Experience Scale (SEES) prior to the stimulation protocol each day. Results: There was a modest decrease in all H-reflex measures from the first to third test day, but it was non-significant (P's>0.05). All measures of the H-reflex exhibited a profound reduction following vibration on test day four, and then returned to baseline levels on test day five (P's<0.05). The intraclass correlation coefficient (ICC) for H-reflex amplitude at 5% of Mmax was 0.85. The ICC for the slope of the regression line was 0.79 while it was 0.89 for dH/dVmax. Maximum M-wave amplitude had an ICC of 0.96 attesting to careful methodological controls. The SEES subscales of fatigue and psychological well-being remained unchanged IV across the five days. The psychological distress subscale (P<O.05), as well as the amplitude of the H-reflex_.at5% Mmax·(P<O.OI) showed a significant cubic trend across the live days. No significant correlation was found between Hs% and psychological distress (P>O.05). Conclusions: The peak of the first derivative of the H-reflex stimulus-response curve (dH/dVmax) was shown to have comparable reliability and sensitivity to other more established measures of excitability. Psychological distress and the amplitude of the H-reflex at 5% Mmax follow similar trends across days, however there was no significant correlation between the two measures. Significance: The proposed method appears to be a more robust measure ofH-reflex excitability than the other methods tested. As such it would be an advantageous method to apply in clinical and investigative settings. Additionally, the results suggest that the relationship between psychological distress and H-reflex amplitude should be investigated further.
    • The reliability of an isometric test based on constant perception of effort

      Kilburn, Shane Michael.; Applied Health Sciences Program (Brock University, 2009-02-16)
      To date there is no documented procedure to extrapolate findings of an isometric nature to a whole body performance setting. The purpose of this study was to quantify the reliability of perceived exertion to control neuromuscular output during an isometric contraction. 21 varsity athletes completed a maximal voluntary contraction and a 2 min constant force contraction at both the start and end of the study. Between pre and post testing all participants completed a 2 min constant perceived exertion contraction once a day for 4 days. Intra-class correlation coefficient (R=O.949) and standard error of measurement (SEM=5.12 Nm) concluded that the isometric contraction was reliable. Limits of agreement demonstrated only moderate initial reliability, yet with smaller limits towards the end of 4 training sessions. In conclusion, athlete's na"ive to a constant effort isometric contraction will produce reliable and acceptably stable results after 1 familiarization sessions has been completed.