• The effects of consistency and inconsistency between attentional focus and task objective in learning a golf putting task

      Milne, Adrienne; Applied Health Sciences Program (Brock University, 2013-10-10)
      Converging evidence has demonstrated learning advantages when an individual is instructed to focus their attention externally. However, many of the motor tasks utilized in past research had clear external objectives (i.e., putting accuracy), creating a compatible relationship between an external focus of attention (i.e., outcome) and an external task objective (i.e., putting accuracy). The present study examined whether or not the consistency of instructions and task objective would differentially impact the acquisition of a golf putting task. Participants performed a putting task in a control condition or in one of four experimental conditions resulting from the factorial interaction of task instructions (internal or external) and task objective (internal or external). The retention and transfer data revealed that participants who received an external task objective demonstrated superior outcome scores. Participants who received technique information paired with outcome information demonstrated superior technique scores.
    • Effects of dairy consumption and exercise on body composition in overweight/obese adolescent females: The I.D.E.A.L. (Improving Diet, Exercise, and Lifestyle) for Adolescents Study

      Calleja, Melissa; Applied Health Sciences Program
      Exercise training is known to decrease fat mass and increase lean mass in adolescents and adults. In adults, the consumption of dairy foods, as part of a lifestyle intervention, can promote favourable body composition changes. However, results of the few studies examining the combined effects of exercise and dairy consumption on body composition in adolescents are inconclusive. The purpose of our study was to determine whether increased dairy consumption, along with structured exercise training and dietary guidance within a weight management program, can promote favourable changes in body composition, anthropometry and cardiovascular fitness in overweight/obese adolescent females. Sixty-one adolescent females (age: 14.8±2.2 y; BMI: 29.3±5.1 kg/m2) were randomized to 3 groups: recommended dairy (RDa; n=24); low dairy (LDa; n=22); control (GCon; n=8), and 54 participants completed the study. The RDa and LDa groups participated in a 12-week, individualized, eucaloric, lifestyle modification intervention consisting of mixed-mode exercise 3x/week, and 5 nutritional counselling sessions with a registered dietitian. RDa group was provided 4 servings/day of dairy (as milk, Greek yogurt and cheese), while LDa maintained habitually low intakes of 0-2 servings/day. Seven-day food records were collected at weeks 0 and 12. Body composition, waist/hip circumference, and VO2peak were assessed for all groups at weeks 0 and 12. Both RDa and LDa decreased body fat (-1.7±1.5%, -1.2±1.1%, respectively), fat mass (-1.3±2.1kg, -1.1±2.0kg, respectively) and subcutaneous fat thickness (-12.5±10.0mm, -9.1±9.4mm, respectively) compared with the GCon (0.3±1.3%, 0.8±1.8kg, 3.0±8.0mm, respectively) (p ≤0.002 for all). RDa decreased fat mass (kg) more than LDa (p=0.001). Both RDa and LDa gained more lean mass (1.5±1.9kg, 0.7±1.6kg, respectively) than GCon (0.5±1.4kg). RDa increased lean mass more than LDa (p≤0.001). VO2peak (ml/min/kg) did not differ between groups following the intervention (p=0.093). These findings suggest that the inclusion of a variety of dairy foods in the diet of overweight/obese adolescent girls, as part of a weight management intervention program, is beneficial to the overall improvement in body composition.
    • Effects of dietary restraint and oral contraceptives on bone strength and bone turnover in young women

      Di Giovanni, Gioia.; Applied Health Sciences Program (Brock University, 2006-06-29)
      ABSTRACT Introduction The purpose of this study was to assess specific osteoporosis-related health behaviours and physiological outcomes including daily calcium intake, physical activity levels, bone strength, as assessed by quantitative ultrasound, and bone turnover among women between the ages of 18 and 25. Respective differences on relevant study variables, based on dietary restraint and oral contraceptive use were also examined. Methods One hundred women (20.6 ± 0.2 years of age) volunteered to participate in the study. Informed written consent was obtained by all subjects prior to participation. The study and all related procedures were approved by the Brock University Research Ethics Board. Body mass, height, relative body fat, as well as chest, waist and hip circumferences were measured using standard procedures. The 10-item restrained eating subscale of the Dutch Eating Behaviour Questionnaire (DEBQ) was used to assess dietary restraint (van Strien et al., 1986). Daily calcium intake was assessed by the Rapid Assessment Method (RAM) (Hertzler & Frary 1994). Weekly physical activity was documented by the 4-item Godin Leisure-Time Exercise Questionnaire (Godin & Shephard 1985). Bone strength was determined from the speed of sound (SOS) as measured by QUS (Sunlight 7000S). SOS measurements (m/s) were taken of the dominant and non-dominant sides of the distal one third of the radius and the mid-shaft of the tibia. Resting blood samples were collected from all subjects between 9am and 12pm, in order to evaluate the impact of lifestyle factors on biochemical markers of bone turnover. Blood was collected during the early follicular phase of the menstrual cycle (approximately days 1-5) for all subjects. Samples were centrifliged and the serum or plasma was aliquoted into separate tubes and stored at -80°C until analysis. The bone formation markers measured were Osteocalcin (OC), bone specific alkaline phosphatase (BAP) and 25-OH vitamin D. The bone resorption markers measured were the carboxy (CTx) and amino (NTx) terminal telopeptides of type-I collagen crosslinks. All markers were assessed by ELISA. Subjects were divided into high (HDR) and low dietary restrainers (LDR) based on the median DEBQ score, and also into users (BC) and non-users (nBC) of oral contraceptives. A series of multiple one way ANOVA's were then conducted to identify differences between each set of groups for all relevant variables. A two-way ANOVA analysis was used to explore significant interactions between dietary restraint and use of oral contraceptives while a univariate follow-up analysis was also performed when appropriate. Pearson Product Moment Correlations were used to determine relationships among study variables. Results HDR had significantly higher BMI, %BF and circumference measures but lower daily calcium intake than LDR. There were no significant differences in physical activity levels between HDR and LDR. No significant differences were found between BC and nBC in body composition, calcium intake and physical activity. HDR had significantly lower tibial SOS scores than LDR in both the dominant and non-dominant sites. The post-hoc analysis showed that within the non-birth control group, the HDR had significantly lower tibial SOS scores of bone strength when compared to the LDR but Aere were no significant differences found between the two dietary restraint groups for those currently on birth control. HDR had significantly lower levels of OC than LDR and the BC group had lower levels of BAP than the nBC group. Consistently, the follow-up analysis revealed that within those not on birth control, subjects who were classified as HDR had significantly (f*<0.05) lower levels of OC when compared with LDR but no significant differences were observed in bone turnover between the two dietary restraint groups for those currently on birth control. Physical activity was not correlated with SOS scores and bone turnover markers possibly due to the low physical activity variability in this group of women. Conclusion This is the first study to examine the effects of dietary restraint on bone strength and turnover among this population of women. The most important finding of this study was that bone strength and turnover are negatively influenced by dietary restraint independent of relative body fat. In general, the results of the present thesis suggest that dietary restraint, oral contraceptive use, as well as low daily calcium intake and low physical activity levels were widespread behaviours among this population of college-aged women. The young women who were using dietary restraint as a strategy to lose weight, and thus were in the HDR group, despite their higher relative body fat and weight, had lower scores of bone strength and lower levels of markers of bone turnover compared to the low dietary restrainers. Additionally, bone turnover seemed to be negatively affected by oral contraceptives, while bone strength, as assessed by QUS, seemed unaffected by their use in this population of young women. Physical activity (weekly energy expenditure), on the other hand, was not associated with either bone strength or bone tiimover possibly due to the low variability of this variable in this population of young Canadian women.
    • The effects of distraction on threat-related changes in attention focus and postural control

      Watson, Alexander; Applied Health Sciences Program
      The purpose of this thesis was to investigate whether threat-related changes in attention focus and postural control could be modified using distraction. Healthy young adults (N=21) stood without (No Threat) and with (Threat) the possibility of receiving an unpredictable anterior or posterior support surface translation under conditions in which they were required to perform or not perform a distractor task. The results of the thesis showed significant threat-related changes in attention focus and postural control independent of distraction. When performing with distraction compared to without, threat-related changes in high-frequency sway (1.0-2.5 Hz) were significantly reduced, and threat-related changes in attention focus to self-regulatory strategies tended to be reduced. These findings suggest that distraction may modify threat-related changes in attention focus and postural control.
    • The effects of estimating good vs. poor knowledge of results during acquisition of a spatial motor task

      Azizieh, Jana; Applied Health Sciences Program (Brock University, 2012-09-13)
      Recent studies have shown that providing learners Knowledge of Results (KR) after “good trials” rather than “poor trials” is superior for learning. The present study examined whether requiring participants to estimate their three best or three worst trials in a series of six trial blocks before receiving KR would prove superior to learning compared to not estimating their performance. Participants were required to push and release a slide along a confined pathway using their non-dominant hand to a target distance (133cm). The retention and transfer data suggest those participants who received KR after good trials demonstrated superior learning and performance estimations compared to those receiving KR after poor trials. The results of the present experiment offer an important theoretical extension in our understanding of the role of KR content and performance estimation on motor skill learning.
    • The Effects of Greek Yogurt and Exercise on Strength, Muscle Thickness and Body Composition in Untrained, University-Aged Males

      Bridge, Aaron; Applied Health Sciences Program
      Previous research has shown the effectiveness of milk/whey protein plus exercise on increasing muscle size, optimizing body composition and increasing strength in adult males and females. Greek yogurt (GY) contains similar muscle-supporting nutrients as milk yet it is different in several ways including being a solid food, and it has yet to be investigated in this context. Thus, the purpose of this study was to assess the effects of GY consumption plus exercise (resistance and plyometric) training on strength, muscle thickness and body composition. Thirty untrained, university-aged (18-25 years) males were randomized to 2 groups (fat-free, plain GY; n= 15, or a Placebo Pudding [PP; isoenergetic carbohydrate-based pudding]; n= 15) and underwent a combined resistance/plyometric training program 3d/week for 12 weeks. They consumed either GY (20 g protein per serving) or PP (0 g protein per serving) daily (GY: 3x200 g on training days and 2x150 g on non-training days; spread throughout the day). After 12 weeks, both groups significantly increased strength, muscle thickness and fat-free mass from baseline (p<0.05). GY gained more strength (GY; 26.8%, PP; 15.1%) than PP in 3 of 4 exercises determined by 1-RM (p<0.05). GY gained more biceps brachii muscular thickness (GY; 16.4%, PP; 7.1%) than PP determined by ultrasound (p<0.05). GY also increased fat-free mass (GY; 3.9%, PP; 2.3%) and reduced % body fat (GY; -1.1%, PP; 0.1%) more than PP determined by air-displacement plethysmography (p<0.05). Thus, consumption of GY during a training program resulted in improved strength, muscle thickness and body composition over a carbohydrate-based placebo. Given the benefits of consuming GY and its distinctiveness from milk, GY may offer a plausible, post-exercise, nutrient-rich alternative for positive strength, muscle and body composition adaptations.
    • The effects of hyperoxia on exercise performance in the cold

      Ferguson, Steven; Applied Health Sciences Program
      This study tested whether hyperoxia improves exercise performance in moderately-cooled individuals, along with the relationship between cold and hyperoxia on cerebral and muscle oxygenation as potential mechanisms for improvement. Twelve healthy trained male cyclists each completed self-paced 15 km time trials (TT) a week apart in three environmental conditions: Neutral (23°C, FiO2: 0.21), Cold (0°C, FiO2: 0.21), and Cold+Hyper (0°C, FiO2: 0.40). Cold conditions were done after participants were passively cooled by 0.5°C rectal temperature. Performance improved with hyperoxia as TT time for Cold+Hyper was faster than Cold, with no difference found compared to Neutral (Neutral: 1479 ± 75s, Cold: 1509 ± 88s, Cold+Hyper: 1482 ± 85s). Cerebral oxygenation in Neutral and Cold+Hyper was higher than Cold throughout the TT, while Cold+Hyper reached similar levels as Neutral by 2.5 km. Improvement in TT time are likely linked to increased O2 availability allowing for improved aerobic metabolism throughout the body.
    • Effects of Instruction on Walking and Turning Performance in Individuals with Parkinson's Disease

      Pfeiffer, Jacob; Applied Health Sciences Program (Brock University, 2013-09-18)
      Parkinson’s disease (PD) is characterized by postural instability and gait impairment. Verbal instructions can reduce postural sway and improve gait performance in PD. For gait, this evidence is limited to unobstructed straight-path walking. As falls in PD often occur when turning, the purpose of this thesis was to determine if instructions can benefit turning performance in this population. Twelve individuals with PD performed two walking tasks (normal walking, walking with a 180 degree turn) under four instruction conditions (no instruction, take big steps, make larger trunk movements, focus on end and/or turn point). Task duration and trunk yaw and roll sway were calculated. In general, the results demonstrated that the instruction to take big steps improved performance for both tasks compared to providing no instruction or externally based instruction. These results suggest that instructions related to step amplitude may facilitate walking and turning performance in PD.
    • Effects of isometric elbow flexion on electromyographic spike analysis

      Lester, Steven M.; Applied Health Sciences Program (Brock University, 2005-06-15)
      The main objective of this research was to examine the relationship between surface electromyographic (SEMG) spike activity and force. The secondary objective was to determine to what extent subcutaneous tissue impacts the high frequency component of the signal, as well as, examining the relationship between measures of SEMG spike shape and their traditional time and frequency analogues. A total of96 participants (46 males and 50 females) ranging in age (18-35 years), generated three 5-second isometric step contractions at each force level of 40, 60, 80, and 100 percent of maximal voluntary contraction (MVC). The presentation of the contractions was balanced across subjects. The right arm of the subject was positioned in the sagittal plane, with the shoulder and elbow flexed to 90 degrees. The elbow rested on a support in a neutral position (mid pronation/mid supination) and placed within a wrist cuff, fastened below the styloid process. The wrist cuff was attached to a load cell (JR3 Inc., Woodland, CA) recording the force produced. Biceps brachii activity was monitored with a pair of Ag/AgCI recording electrodes (Grass F-E9, Astro-Med Inc., West Warwick, RI) placed in a bipolar configuration, with an interelectrode distance (lED) of 2cm distal to the motor point. Data analysis was performed on a I second window of data in the middle of the 5-second contraction. The results indicated that all spike shape measures exhibited significant (p < 0.01) differences as force increase~ from 40 to 100% MVC. The spike shape measures suggest that increased motor unit (MU) recruitment was responsible for increasing force up to 80% MVC. The results suggested that further increases in force relied on MU III synchronization. The results also revealed that the subcutaneous tissue (skin fold thickness) had no relationship (r = 0.02; P > 0.05) with the mean number of peaks per spike (MNPPS), which was the high frequency component of the signal. Mean spike amplitude (MSA) and mean spike frequency (MSF) were highly correlated with their traditional measures root mean square (RMS) and mean power frequency (MPF), respectively (r = 0.99; r = 0.97; P < 0.01).
    • The effects of manipulated augmented sensory feedback on error detection when using a touch screen

      Lai, Sharon; Applied Health Sciences Program
      The purpose of the present study was to determine which augmented sensory modality would best develop subjective error-detection capabilities of learners performing a spatial-temporal task when using a touch screen monitor. Participants were required to learn a 5-digit key-pressing task in a goal time of 2550 ms over 100 acquisition trials on a touch screen. Participants were randomized into 1 of 4 groups: 1) visual-feedback (colour change of button when selected), 2) auditory-feedback (click sound when button was selected), 3) visual-auditory feedback (both colour change and click sound when button was selected), and 4) no-feedback (no colour change or click sound when button was selected). Following each trial, participants were required to provide a subjective estimate regarding their performance time in relation to the actual time it took for them complete the 5-digit sequence. A no-KR retention test was conducted approximately 24-hours after the last completed acquisition trial. Results showed that practicing a timing task on a touch screen augmented with both visual and auditory information may have differentially impacted motor skill acquisition such that removal of one or both sources of augmented feedback did not result in a severe detriment to timing performance or error detection capabilities of the learner. The present study reflects the importance of multimodal augmented feedback conditions to maximize cognitive abilities for developing a stronger motor memory for subjective error-detection and correction capabilities.
    • Effects of Maternal Folic Acid Supplementation on Skeletal Muscle Function and Metabolism in Male and Female CD-1 Mouse Offspring

      Saint, Caitlin; Applied Health Sciences Program
      In 1998, folic acid (FA) fortification of all white flour, enriched pasta and cornmeal products became mandatory in Canada to reduce the risk of neural tube defects at birth. Furthermore, Health Canada and the Society of Obstetricians and Gynaecologists of Canada recommends all women take daily prenatal FA supplements in addition to FA- fortified foods during pregnancy, resulting in pregnant women being exposed to approximately 4 times higher FA during pregnancy than the current recommended guidelines. However, the influence of maternal FA supplementation on offspring development, specifically muscle, is currently unknown. Skeletal muscle is one of the most abundant tissues in the human body and is essential for locomotion and energy metabolism. Thus, the purpose of this study was to determine the effect of supplemental FA (4 times higher than normal dietary consumption), in utero and throughout suckling on muscle function and metabolism in male and female CD-1 mouse offspring. The major findings were ~25% faster contractions in EDL, characterized by a more rapid relaxation rate, and ~15% slower contractions, characterized by a reduced force development rate, in SOL among females in FA group, with no differences in contractile function seen between groups in males. Additionally, carbohydrate metabolism markers in the FA group decreased in SOL among females, whereas, carbohydrate and oxidative metabolism markers increased in EDL and SOL, respectively, among males. These findings suggest that exposure to folic acid supplementation in utero and throughout suckling programs skeletal muscle function and metabolism in a sex-specific manner.
    • Effects of naringenin on glucose uptake in L6 skeletal muscle cells

      Zygmunt, Katarzyna.; Applied Health Sciences Program (Brock University, 2009-02-16)
      Diabetes mellitus is a disorder of inadequate insulin action and consequent high blood glucose levels. Type 2 diabetes accounts for the majority of cases of the disease and is characterized by insulin resistance and relative insulin deficiency resulting in metabolic deregulation. It is a complex disorder to treat as its pathogenesis is not fully understood and involves a variety of defects including ~-cell failure, insulin resistance in the classic target tissues (adipose, muscle, liver), as well as defects in a-cells and kidney, brain, and gastrointestinal tissue. Present oral treatments, which aim at mimicking the effects of insulin, remain limited in their efficacy and therefore the study of the effects of novel compounds on insulin target tissues is an important area of research both for potentially finding more treatment options as well as for increasing our knowledge of metabolic regulation in health and disease. In recent years the extensively studied polyphenol, resveratrol, has been reported to have antidiabetic effects showing that it increases glucose uptake by skeletal muscle cells and prevents fatty acid-induced insulin resistance in vitro and in vivo. Naringenin, a citrus flavonoid with structural similarities to resveratrol, is reported to have antioxidan.t, antiproliferative, anticancer, and anti-inflammatory properties. Effects on glucose and lipid metabolism have also been reported including blood glucose and lipid lowering effects. However, whether naringenin has insulinlike effects is not clear. In the present study the effects of naringenin on glucose uptake in skeletal muscle cells are examined and compared with those of insulin. Naringenin treatment of L6 myotubes increased glucose uptake in a dose- and time dependent manner and independent of insulin. The effects of naringenin on glucose uptake achieved similar levels as seen with maximum insulin stimulation and its effect was additive with sub-maximal insulin treatment. Like insulin naringenin treatment did not increase glucose uptake in myoblasts. To elucidate the mechanism involved in naringenin action we looked at its effect on phosphatidylinositol 3-kinase (PI3K) and Akt, two signalling molecules that are involved in the insulin signalling cascade leading to glucose uptake. Naringenin did not stimulate basal or insulinstimulated Akt phosphorylation but inhibition of PI3K by wortmannin partially repressed the naringenin-induced glucose uptake. We also examined naringenin's effect on AMP-activated protein kinase (AMPK), a molecule that is involved in mediating glucose uptake by a variety of stimuli. Naringenin stimulated AMPK phosphorylation and this effect was not inhibited by wortmannin. To deduce the nature of the naringenin-stimulated AMPK phosphorylation and its impact on glucose uptake we examined the role of several molecules implicated in mod.ulating AMPK activity including SIRTl, LKB 1, and ca2+ Icalmodulin-dependent protein kinase kinase (CaMKK). Our results indicate that inhibition of SIRTI did not prevent the naringeninstimulated glucose uptake Of. AMPK phosphorylation; naringenin did not stimulate LKB 1 phosphorylation; and inhibition of CaMKK did not prevent naringeninstimulated glucose uptake. Inhibition of AMPK by compound C also did not prevent naringenin-stimulated glucose uptake but effectively inhibited the phosphorylation of AMPK suggesting that AMPK may not be required for the naringenin-stimulated glucose uptake.
    • Effects of pelvic 3D-CRT versus IMRT radiation therapy on circulating pro-inflammatory cytokines in high risk Prostate Cancer patients

      Douvi, Georgia; Applied Health Sciences Program
      This study examined the effects of pelvic radiation therapy on the levels of circulating pro-inflammatory cytokines (cPIC) in high-risk prostate cancer patients, who received pelvic radiation therapy delivered either by 3-dimensional radiation therapy pelvic (3D CRT) or intensity-modulated radiation therapy (IMRT). Subjects included 90 patients who had not previously received treatment for their prostate cancer, and who were planned to receive androgen deprivation therapy for three years, plus concurrent pelvic and prostate boost radiation therapy. Blood samples were drawn at least 3 months into androgen deprivation therapy, before initiation of pelvic 3D-CRT or IMRT (baseline), and on days 5 and 25 of radiation treatment. Samples were analyzed for TNF-α, INF-γ, IL-4, IL-6, IL-8 and IL-10. There were no significant differences between treatment groups for any of the cytokines at any time point. When the two treatment groups were combined into a single group, a significant time/dose effect was observed for IL-4 and INF-γ, which both significantly decreased from baseline to day 25, but the effect size of this change was small (0.30 and 0.24, respectively). There was no significant time effect for the other cytokines. These results suggest that in patients with high risk prostate cancer, receiving treatment with androgen deprivation therapy and pelvic radiation therapy, cPIC are not significantly altered in response to radiation therapy compared to baseline. The small but significant changes in IL-4 and INF-γ over time suggest a potential immunomodulating effect of radiation therapy. Further studies are needed to determine the potential of cPIC as biomarkers of radiation therapy toxicity.
    • Effects of Plyometric and Resistance Training on Muscle Strength and Neuromuscular Function in Young Adolescent Soccer Players

      McKinlay, Brandon; Wallace, Phillip; Long, Devon; Dotan, Phillip; Falk, Bareket; Applied Health Sciences Program
      This study examined the effect of 8-weeks of resistance (RT) and plyometric (PLYO) training on maximal strength, power and jump performance compared with no added training (CON), in young male soccer players. Forty-one 11-13 year-old soccer players were divided into three groups (RT, PLYO, CON). All participants completed 5 isometric knee extensions at 90° and 5 isokinetic knee extensions at 240°/s pre- and post-training. Peak torque (PT), peak rate of torque development (pRTD), electromechanical-day (EMD), rate of muscle activation (Q30), muscle cross-sectional area (mCSA) and jump performance were examined. Both RT and PLYO resulted in significant (p < 0.05) increases in PT, pRTD and jump performance. RT resulted in significantly greater increases in both isometric and isokinetic PT, while PLYO resulted in significantly greater increases in isometric pRTD and jump performance compared with CON (p < 0.05). Q30 increased to a greater extent in PLYO (20%) compared with RT (5%) and CON (-5%) (p = 0.1). In conclusion, 8-weeks of RT and PLYO resulted in significant improvements in muscle strength and jump performance. RT appears to be more effective at eliciting increases in maximal strength while PLYO appears to enhance explosive strength, mediated by possible increases in the rate of muscle activation.
    • Effects of Post Exercise Protein Supplementation on Bone Turnover in Adolescent Swimmers

      Theocharidis, Alexandros; Applied Health Sciences Program
      Objective: To compare the effects of whey protein supplementation to an isocaloric carbohydrate beverage consumed immediately after an intense swimming trial on the promotion of bone turnover in adolescent swimmers, with water provided as a placebo to the control group. Methods: Fifty-eight male (n=27, 14.04±1.5 years) and female (n=31, 13.75±1.8 years) swimmers were stratified into three groups matched for age, body mass and male/female split. The protein group consumed two post-exercise beverages of 0.3 g/kg of whey protein each, the isocaloric carbohydrate group consumed two post-exercise beverages of 0.3g/kg of maltodextrin and the control group had flavoured water. Participants provided one morning, fasted, blood sample, performed an exercise trial consisting of multiple bouts of intense swimming and then consumed their respective post-exercise beverages 2h apart. Participants provided a second blood sample ~8h from baseline, and returned 24h later for a follow-up, morning, fasted blood sample. Markers of bone formation (procollagen type 1 intact N-terminal propeptide [PINP]) and resorption (carboxy-terminal collagen crosslinks [CTXI]) were measured in serum. Bone turnover rate and balance were estimated using the Multiple of Medians of CTXI and PINP. Results: A three-way repeated measures ANOVA (time-by-group-by-sex) showed a significant time-by-group interaction for CTXI (p=0.021), with no effect of, or interaction with sex, reflecting a significant increase from baseline to 8h in the protein group only, which subsequently decreased significantly to lower values than baseline at 24h. For PINP, there was a time-by-group-by-sex interaction (p=0.04); however, despite the 3-way interaction, none of the post-hoc comparisons were statistically significant. The bone turnover rate showed a time-by-group interaction (p<0.001), with no effect of, or interaction with sex. Specifically, the bone turnover rate significantly increased at 8h in the protein group only, with the bone turnover balance favouring formation at 8h and 24h. Conclusion: These results shed light on the potential importance of protein supplied shortly after intense exercise in promoting bone turnover up to 24h following the exercise in adolescent athletes.
    • The effects of postural threat on cognitive strategies used to maintain upright stance

      Huffman, Jennifer.; Applied Health Sciences Program (Brock University, 2009-02-16)
      It is well established that postural threat modifies postural control, although little is known regarding the underlying mechanism(s) responsible. It is possible that changes in postural control under conditions of elevated postural threat result from alterations in cognitive strategies. The purpose of this study was to determine the influence of elevated postural threat on cognitive strategies and to determine the relationship between postural control, psychological, and cognitive measures. It was hypothesized that elevated postural threat would cause a shift to more conscious control of posture. It was also expected that a relationship between fear of falling and postural control would exist that could be explained by changes in conscious control of posture. Forty-eight healthy young adults stood on a force plate at two different surface heights: ground level (LOW) and 3.2m above ground level (HIGH). Center of pressure (COP) summary measures calculated to quantify postural control were the mean position (AP-COP MP), root mean square (AP-COP RMS) and mean power frequency (AP-COP MPF) in the anteriorposterior direction. Trunk sway measures calculated in the pitch direction were trunk angle and trunk velocity. Psychological measures including perceived balance confidence, perceived fear of falling, perceived anxiety, and perceived stability were self reported. As a physiological indicator of anxiety, electrodermal activity was collected. The cognitive strategies assessed were movement reinvestment and attention focus. A modified state-sp-ecific version of the Movement Specific Reinvestment Scale was used to measure conscious motor processing (CMP) and movement self-consciousness (MSC). An attention focus questionnaire was developed to assess the amount of attention directed to internal and external sources. An effect of postural threat on cognitive strategies was observed as participants reported more conscious control and a greater concern or worry about their posture at the HIGH postural threat condition as well as an increased internal and external focus of attention. In addition changes in postural control, psychological, and physiological measures were found. The participants leaned away from the edge of the platform, the frequency of their postural adjustments increased, and the velocity of their trunk movements increased. Participants felt less confident, more fearful, more anxious, and less stable with an accompanying increase in physiological anxiety. Significant correlations between perceived anxiety, AP-COP MP, and cognitive measures revealed a possible relationship that could be mediated by cognitive measures. It was found that with greater conscious motor processing, more movement self-consciousness, and a greater amount of attention focused externally there was a larger shift of the mean position away from the edge of the platform. This thesis provides evidence that postural threat can influence cognitive strategies causing a shift to more conscious control of movement which is associated with leaning away from the edge of the platform. Shifting the position of the body away from the direction of the postural threat may reflect a cognitive strategy to ensure safety in this situation due to the inability to employ a stepping strategy when standing on an elevated platform.
    • Effects of Proactive and Retroactive Augmented Information on Physiological Responses in Learning a Novel Motor Skill

      Hart, Amanda; Applied Health Sciences Program (Brock University, 2012-03-13)
      Previous research has demonstrated superior learning by participants presented with augmented task information retroactively versus proactively (Patterson & Lee, 2008; 2010). Theoretical explanations of these findings are related to the cognitive effort invested by participants during motor skill acquisition. The present study extended previous research by utilizing the physiological index, power spectral analysis of heart rate variability, previously shown to be sensitive to the degree of cognitive effort invested during the performance of a motor task (e.g., increase cognitive effort results in increased LF/HF ratio). Participants were required to learn 18 different key-pressing sequences. As expected, the proactive condition demonstrated superior RS during acquisition, with the retroactive condition demonstrating superior RS during retention. Measures of LF/HF ratio indicated the retroactive participants were investing significantly less cognitive effort in the retention period compared to the proactive participants (p< .05) as a function of learning.
    • The effects of R(+)-lipoic acid supplementation on regulation of human skeletal muscle pyruvate dehydrogenase

      Staples, Elizabeth M.; Applied Health Sciences Program (Brock University, 2006-06-04)
      This thesis investigated whole body glucose disposal and the adaptive changes in skeletal muscle carbohydrate metabolism following 28 d of supplementation with 1000 mg R(+)-lipoic acid in young sedentary males (age, 22.1 ± 0.67 yr, body mass, 78.7 ± 10.3 kg, n=9). In certain individuals, lipoic acid decreased the 180-min area under the glucose concentration and insulin concentration curve during an oral glucose tolerance test (OGTT) (n=4). In the same individuals, lipoic acid supplementation decreased pyruvate dehydrogenase kinase activity (PDK) (0.09 ± 0.024 min"^ vs. 0.137 ± 0.023 min'\ n=4). The fasting levels of the activated form of pyruvate dehydrogenase (PDHa) were decreased following lipoic acid (0.42 ± 0.13 mmol-min'kg'^ vs. 0.82 ± 0.32 mmolrnin'^kg"\ n=4), yet increased to a greater extent during the OGTT (1.21 ± 0.34 mmol-min'kg"' vs. 0.81 ±0.13 mmolmin"'kg'\ n=4) following hpoic acid supplementation. No changes were demonstrated in the remaining subjects (n=5). It was concluded that improved glucose clearance during an OGTT following lipoic acid supplementation is assisted by increased muscle glucose oxidation through increased PDHa activation and decreased PDK activity in certain individuals.
    • Effects of Rosemary Extract and Rosemary Extract Polyphenols on Skeletal Muscle Insulin Resistance

      Shamshoum, Hesham; Applied Health Sciences Program
      Skeletal muscle, a major target tissue of insulin, accounts for ~80% of postprandial glucose disposal and plays a significant role in the regulation of glucose homeostasis. Insulin increases muscle glucose uptake by increasing the translocation of intracellularly stored GLUT4 glucose transporters to the plasma membrane through the phosphatidylinositol-3 kinase (PI3K)/Akt signaling pathway. Impaired PI3K/Akt signaling is associated with skeletal muscle insulin resistance (IR), leading to chronically elevated blood glucose levels followed by a compensatory rise in insulin levels. Rosemary extract increases muscle cell glucose uptake but its effects on high glucose/high insulin-induced insulin resistance are not known and is the focus of the present study. Exposure of L6 myotubes to 25mM glucose and 100nM insulin for 24 h, to mimic hyperglycemia (HG) and hyperinsulinemia (HI), abolished the acute insulin-stimulated glucose uptake (I: 183, HG + HI + I: 112 % of basal), attenuated the insulin-stimulated Akt phosphorylation, while increased IRS-1 Ser636/639 phosphorylation indicating insulin resistance. In addition, HG+HI increased mTOR phosphorylation/activation. Importantly, treatment with RE (5 μg/ml) significantly restored the insulin-stimulated glucose uptake (HG + HI + RE + I: 149% of basal) reduced the HG + HI-induced IRS-1 Ser636/639 phosphorylation and mTOR phosphorylation and increased AMPK phosphorylation. Our data indicate a potential of RE to counteract muscle insulin resistance and more research is required to investigate the mechanisms involved.
    • The Effects of Self-Selected vs Researcher-Selected Music on Psychological, Physiological and Performance Outcomes During a Running Task

      Pierre, Jermel; Gammage, Kimberley; Applied Health Sciences Program
      The present study examined the effects of self-selected versus researcher-selected music on psychological, physiological and performance variables during a treadmill running task. Male and female participants (n = 30) performed a 30-minute treadmill run to their own self-selected music, researcher-selected motivational music and a no-music condition. Participants were assessed on intrinsic motivation, enjoyment, RPE, distance and heart rate. A series of repeated measures ANOVAs were used to analyse the data. Results indicated that following listening to their self-selected music, participants reported being more intrinsically motivated, more enjoyment, greater rating of perceived exertion and greater distance run. This study suggest that self-selected music may be an avenue to helping individuals overcome barriers to physical activity such as intrinsic motivation and enjoyment to help promote greater physical activity participation and adherence.