• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 41
  • 15
  • 14
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 80
  • 80
  • 37
  • 35
  • 13
  • 11
  • 11
  • 11
  • 9
  • 9
  • 8
  • 7
  • 6
  • 5
  • 5
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

The Effects of Heat Acclimation on Heat Shock Protein-72 and Lymphocyte Apoptosis

Rola, Kelyn 18 May 2010 (has links)
Heat shock proteins (HSP) improve cellular thermotolerance and protect against stress-induced cell death by reducing micro level damage and mediating apoptotic pathways. HSP72 levels increase in response to nonlethal heat stress in vitro, and occur due a variety of physiological stressful conditions, including heat exposure and exercise, in vivo. Multiple days of exercise in the heat lead to a heat acclimated state of improved whole-body thermotolerance, which is thought to be related to an accumulation of HSP72. Increased HSP72 expression has been shown to decrease apoptosis in vitro; however, the relationship between physiological adaptations to heat acclimation and the subsequent adaptations at the cellular level are less understood. The purpose of this study was to examine if heat acclimation (HA) increases HSP72 and if its protective mechanisms decrease apoptosis in lymphocytes. Twelve recreationally active males completed 8 consecutive days of cycling in 38°C for ~90 min at ~45% VO2max. Lymphocytes were isolated from whole blood pre- and post-exercise on days 1 and 8 of HA. The pre-exercise lymphocytes were heat shocked in vitro for 20, 40, or 60 min at 37, 41, 43, or 45°C to analyze apoptotic responses to heat, and post-exercise samples were analyzed to determine apoptotic responses to exercise. After HA, participants exhibited significantly improved thermotolerance. They experienced a resting plasma volume expansion of 6.29±6.18%, enhanced sweat loss (F=20.479, p=0.001), and decreased heart rate, core temperature, and skin temperature at all time points during the heat tolerance test following HA (F=2.968, p=0.046; F=3.634, p=0.023; and F=6.642, p=0.002, respectively). HSP72-mRNA increased during exercise on days 1 and 8 (4.08±1.09 and 3.80±0.50 fold, respectively), and resting HSP72-mRNA levels increased 2.11±0.35 fold from days 1 to 8. There was no change in in vitro apoptosis due to HA (F=0.820, p=0.385); however, there was an interaction of the time x temperature design used to treat cells (F=43.954, p=0.000), with 45°C being more lethal than all other temperatures at every time point. There was no change in apoptosis due to exercise or HA (F=0.028, p=0.870 and F=0.176, p=0.683, respectively). Without HSP72 protein expression, the exact changes in HSP72 content cannot be elucidated. However, it appears that circulating lymphocytes do not undergo significant changes in HSP72 during whole body heat acclimation. Thus, improved thermotolerance at the organism level may not be associated with improved thermotolerance, i.e. protection against apoptosis, at the cellular level.
22

Pattern Change and Performance: Focus of Attention and Control

Jain, Nitin 20 May 2008 (has links)
The purposes of this study were to compare changes in motor pattern and performance of individuals when utilizing internal, external, or dynamic system perspective when learning the fundamental skill of throwing. Forty right hand dominant college age students (18-25 years) participated in this study. Participants were required to throw a baseball size ball to a target with their non-dominant limb. Participants were randomly placed into four conditions. Condition 1 was Internal Focus condition. Participants in this condition received the following instruction: 1) turn so your right shoulder is closer to the mat, 2) when throwing shift your weight from back leg to front leg, and 3) arch your back and first accelerate the trunk, then shoulder, then upper arm, and finally your hand. Condition 2 was the External Focus condition. Participants in this condition received the following instructions: 1) turn sideways so you are facing the south wall, 2) when throwing shift your weight toward the mat, and 3) throw the ball as if your trunk and arm were like a whip, like a horseman driving his horses. Condition 3 was the Control Parameter condition. Participants in this condition were encouraged to scale up on the control parameter of throwing velocity. Participants in the control parameter condition did not receive any additional augmented information. Condition 4 was Control condition. Participants in this condition did not receive any augmented information nor they scale up on the control parameter. Participants were initially provided instructions and demonstration prior to the first trial. Augmented information was then provided after every 5th throw during practice sessions. The Focus and Control conditions were required to throw the ball at a preferred velocity. Participants practiced twice per week for three weeks for a total of 6 sessions. The seventh session was 10 days after the 6th session. Participants were not provided any information during the 7th retention session. Accuracy of throw related to a target center was recorded for each trial. Two cameras were used to capture the throwing motion. A Peak Motion analysis system used to capture and analyze data. A 2-way (4 x 7) Multivariate analysis of variance (MANVOA) was completed on the three dependent measures of segmental lag (Humerus-Trunk, Forearm-Humerus, and Hand-Forearm). MANOVA was followed by Discriminant Function Analysis (DFA) in order to identify significant functions related to the significant MANOVA. Univariate analysis (ANOVA) was used to determine differences in identified functions by each independent factor. Scheffe post hoc analysis identified measures responsible for significant ANOVA. A two-way (conditions x sessions) ANOVA was completed to determine significant differences in radial error and coefficient of variation of radial error. An alpha level of .05 was selected for all statistical parameters. Results indicated that the control parameter and external focus groups were better instigating pattern change than other groups. The Focus groups demonstrated better performance accuracy over practice sessions. Focus groups also retained performance better than the control parameter and control group. It was concluded that scaling up on a control parameter and External Focus promote pattern change better than internal focus. Focus of Attention was better for retention of performance than the control parameter group.
23

THE EFFECT OF FILTERING ON AUDITORY-PERCEPTUAL RATINGS OF SEVERITY IN HYPOFUNCTIONAL VOICES

George, Candice M. 11 June 2012 (has links)
Voice disorders can have a negative impact on communication. Voice quality is largely a perceptual phenomenon whose judgment relies on the subjective assessment of a listener. Mechanical devices have been developed to augment the voice and improve vocal quality in certain voice disordered individuals. The purpose of this study was to investigate whether signal modification, characterized by amplification alone, filtering alone and/or filtering with amplification, will have an effect on perceived severity of voice quality in breathy voices. Hypofunctional voices were manipulated into four conditions (Original recordings, Amplitude reinforced, Low Pass Filtered, and Low Pass Filtered with Amplitude Reinforcement). Results indicated that a significant main effect was not present (F[3,27] = 2.73, p = 0.64). Pairwise comparisons revealed that this effect was due to a significant difference between the severity ratings for the OR and the LPF stimuli (mean difference = 3.96, p = .037, 95% confidence interval = .296 - 7.629). The results indicate that there was an effect when low pass filtering was present. This condition would help the perceptual quality of a hypofunctional voice if used in an external mechanical device.
24

Is Velocity a Control Parameter for the Development of the Stationary Kick?

Black, Kelley Randall 15 June 2011 (has links)
Although kicking is a fundamental motor skill, little research has been conducted to determine the variables that may alter kicking patterns during the course of human development. The purpose of the current study was to determine if velocity is a control parameter that allows kicking patterns to self-organize to higher levels of efficiency. Twenty-seven participants (16 males, 11 females, ages 7-12 years) performed 5 kicks in each of three conditions: Condition 1, Low velocity (33% of maximum), Condition 2, medium velocity (67% of maximum), and Condition 3, high velocity (maximum). Dependent measures for pattern change were thigh lag, shank lag, and foot lag, as well as peak velocity difference values for the thigh, shank, and foot. Data were collected with a Peak Motus Motion Analysis System. Segemental lag data were analyzed using a 1-way repeated measures MANOVA by condition. Significant MANOVA was followed by a 1-way ANOVA to determine measures responsible for significance. Scheffe post hoc analyses determined specific means responsible for significance. Peak velocity difference values were analyzed using a 1-way MANOVA by condition. A 1-way ANOVA determined measures responsible for significance. Scheffe post hoc analyses determined specific means responsible for significant differences. Pattern change analyses indicated that foot lag was the only variable responsible for the significant difference. As kicking velocity increased, foot lag values became increasingly more negative, indicating that the foot locked with the shank at impact with the ball. Further investigation indicated that participants may be locking the foot with the shank at impact with the ball to produce a greater effective mass of the striking object (the foot), and thus increase the resultant velocity of the ball following impact. Results indicated that velocity is a control parameter that causes kicking patterns to change; however, the pattern change does not favor the development of distal lag.
25

The influence of acute resistive exercise on inflammatory markers in the blood of obese, postmenopausal women.

Patrizi, Robert Michael 18 June 2008 (has links)
Contracting skeletal muscle is capable of producing a metabolic response involving the production of large amounts of intracellular messengers known as cytokines. IL-6 is one cytokine known to be released in response to muscular contraction. Plasma IL-6 concentrations have been shown to increase significantly followed intense resistive exercise, and muscle-derived IL-6 is capable of reducing the inflammatory response of blood mononuclear cells. Purpose: To examine the effects of an acute bout of resistive exercise on inflammatory markers in the blood, 23 obese, postmenopausal women performed a high intensity resistive exercise session and the effects of contraction-induced IL-6 on LPS-stimulated TNF-¥á and IL-1¥â production were measured. Methods: Obese, postmenopausal (65.65 ¡¾ 3.89 years) women (N=23) were acclimated to resistive exercise over a three day period. After the acclimation period, participants were randomized into one of two groups: non-exercising control group (CON; N=11) or exercise group (EX; N=12). At least three days after the third acclimation day, participants reported to the lab and either completed a resistive exercise session (EX) at 80% of their estimated 1-RM, or rested quietly in the lab (CON). Blood samples were obtained pre, post, 2 hours-post, and 24 hours-post exercise. Similar time points were used in the CON group. Blood samples were analyzed using ELISA for plasma IL-6 concentrations. Whole blood samples were stimulated with LPS endotoxin and incubated for 24 hours in physiological conditions (37¨¬C, 5% CO2). LPS-stimulated production of TNF-¥á and IL-1¥â were measured in the stimulated supernatants to assess immunocreativity of blood mononuclear cells. Results: Plasma IL-6 increased significantly following the exercise session (p<0.019), although the difference compared to CON at PO was not significant. Significant leukocytosis occurred following the exercise session. Total white blood cells were increased, as well as numbers of circulating monocytes, neutrophils and lymphocytes immediately following exercise. LPS-stimulated cytokine production was not significantly affected by the exercise session. Plasma cortisol pattern of release was unchanged in the CON group, while the diurnal decrease in cortisol was delayed immediately post-exercise in the EX group. Cortisol remained below baseline values at the 24H sample in EX (p=0.00). Conclusion: Resistive exercise is capable of generating an immune response in elder, postmenopausal women as seen in the significant increase in plasma IL-6 and systemic leukocytosis. Plasma IL-6 exerted its effects on plasma cortisol and mitogen-stimulated, whole blood cultures. The typical decrease in cortisol was not seen in the EX group, likely because of the contraction-induced changes in plasma IL-6. Unfortunately we did not find any significant difference between LPS-stimulated samples, although there was a tendency for significance at PO, indicating that plasma IL-6 was inhibiting pro-inflammatory cytokine release to some degree.
26

Fatigue during high intensity exercise: the interaction between pH and thermal stress.

Rogers, Melissa 22 June 2007 (has links)
Purpose: The purpose of this study was to compare the effects of high intensity, time-to-exhaustion (TTE) cycling in hot and cold environments on pH, LA, bicarbonate , K+, and core temperature (Tc). Methods: Subjects completed four TTE trials: 1) Hot (35oC) 80% VO2max (H80), 2) Cold (10oC) 80% (C80), 3) Hot 100% (H100), and 4) Cold 100% (C100). Blood samples were taken at baseline, 5-min post, and 3-min post-exercise and analyzed for pH, HCO3-, and K+. Results: TTE was different between all trials except H100 and C100. pH was different at REC for all trials except H100 and C100 while LA was different between trials at REC. Bicarbonate was lowest at EXH in H80 and C80; however, HCO3- was lower for H80 and H100 at REC. Potassium was higher at EXH in the hot environments. Tc was higher at EXH for H80 and C80 compared to H100 and C100. Conclusions: Tc likely played a greater role in fatigue during H80 and C80 trials, while pH and HCO3- may have been more important factors during H100 and C100 trials.
27

The effect of two concurrent training programs with different inter-session recovery on musculoskeletal strength

Quebedeaux, Luke Patrick 17 July 2007 (has links)
Background: Gains in musculoskeletal strength acquired via concurrent strength and endurance training have been of lesser magnitude when compared to those acquired when performing strength training alone. This attenuation in strength may be due to a lack of recovery from the high volume of exercise characteristic of concurrent training. Purpose: The purpose of this study is a) to evaluate the relative effectiveness of two concurrent training regimens, differing only in the duration of the rest between the strength and endurance training sessions, with regard to increasing strength and b) to determine if the responses of testosterone and cortisol and the changes in FFM, RMR, and blood urea nitrogen can be identified as contributing factors in this phenomenon. Methods: Twenty-four physically active, untrained males (21 + 1.37 years) completed six weeks of training in one of three groups: a same day concurrent training (SDCT, N=8), an alternate day concurrent training (ADCT, N=10), or a strength training only group (ST, N=6). Body composition measures (body weight, percent body fat, FFM, fat mass), RMR, blood urea nitrogen, VO2max, 1RM bench press, 1RM hac-squat, daily total caloric intake, and percentage energy macronutrients were measured before and after training. Salivary testosterone, salivary cortisol, and the salivary T:C were measured pre-, mid-, and post-training. All data was analyzed using the appropriate 2-way ANOVA with repeated measures. Results: 1RM bench press, 1RM hac-squat, VO2max, FFM, body mass, RMR, salivary cortisol, and fat consumption significantly increased from pre- to post-training. The only significant interaction was that of blood urea nitrogen, which decreased in the SDCT group and increased in the ST group from pre- to post- training. Conclusions: The lack of any significant difference among the study groups regarding musuloskeletal strength, cardiorespiratory endurance, body composition, and RMR does not support the existance of an interference phenomenon regarding the musculoskeletal adaptations to concurrent training.
28

Assessing Differences in Strength and Conditioning Coach Self-Perceptions of Leadership Style at the NBA, Division I, and Division II Level

Magnusen, Marshall James 10 August 2007 (has links)
There is significant lack of sport psychology research that relates to strength and conditioning coaches. Therefore the purpose of this study was to examine the differences in self-perceived leadership styles of NBA, Division I mens basketball, and Division II mens basketball strength and conditioning coaches. The self-perceived leadership styles of 145 mens basketball strength and conditioning coaches (NBA = 22, DI = 92, and DII = 31) were obtained using the Revised Leadership Scale for Sport (Zhang, Jensen, & Mann, 1996; Jambor & Zhang, 1997). Some questions of the RLSS were adjusted slightly to reflect a weight room setting instead of an athletic setting. All subscales demonstrated a high reliability except for autocratic. Cronbachs Alpha for leadership was: .819 for democratic, .520 for autocratic, .813 for positive feedback, .831 for training and instruction, .724 for social support, and .741 for situational considerations. ANOVA results identified significance on five of the six subscales. Only positive feedback did not show significance. Scheffe post hoc tests were conducted on the five significant leadership subscales. Key findings showed that differences do exist between competitive level and strength and conditioning coach self-perceived leadership styles. The findings of the study indicate the importance of examining differences between competitive level and strength coach leadership styles as well as future studies to examine how strength coaches perceive themselves in comparison to how athletes perceive their strength coachs leadership styles.
29

An Examination of Relative and Absolute Timing in Children, Adolescents, and Adult Vertical Jumpers

Greak, Patrick Jamail 13 October 2009 (has links)
Horizontal Jumping is a well studied fundamental motor skill with established developmental sequences. Surprisingly, comparatively little work has been completed concerning vertical jumping despite its use in many sport and recreational activities. The purpose of this study was to determine age related differences in vertical jump coordination and performance through the examination of kinematic variables. Twenty-eight participants in three different age groups (9 children age 4-6 yrs, 9 adolescents age 12-14 yrs, and 10 adults age 18-25 yrs) performed 5 maximum vertical jumps with countermovement. Three-dimensional data were collected with a Peak Motus Motion Analysis System. Dependent measures were angular displacement of hip, knee, and ankle joint at low point of crouch, time to peak velocity of joints and segments relative to take-off, peak displacement and time to peak displacement of joints and segments relative to take-off, timing between segments and joint angles from crouch to take-off, time from standing to crouch position of counter movement, time from crouch position to take-off, and height jumped. Segmental and joint data were analyzed across age with oneway MANOVA. Time to crouch, time to take off, and height jumped were analyzed with separate oneway ANOVA. Analyses indicated both qualitative and quantitative differences in dependent measures across age groups. Specifically, the knee and ankle joints of adults and adolescents reached peak velocity after take-off, whereas , only the ankle joint of children reached peak velocity after take-off. Also, there was greater height jumped, greater displacement of the hip joint, and greater time to take off with an increase in age. Results are discussed relative to implications for the development of control and coordination for the vertical jump.
30

Control Parameter and Critical Value for Throwing: An Investigation of Ball Diameter to Hand Length Ratio

Lee, Changwoo 06 December 2007 (has links)
The purposes of this study were to; 1) investigate ball diameter as a control parameter by systematically adjusting the ratio of ball diameter and hand length; 2) determine any differences in pattern change relative to skill level of the thrower; and 3) determine critical values for change in pattern. Forty university students served as participants for this study. The average hand length was 18.74 cm with a standard deviation of 0.64 cm. Participants threw 10 times at 50% of maximum velocity. There was no requirement for accuracy. Segmental lag was digitized from trajectory graphs of segmental velocity. For data collection, participants threw balls of six different diameters. The only augmented information that was provided participants was whether velocity of throw was good or if they needed to slow down or speed up. Participants were able to maintain a 50% throwing velocity successfully during collection of data. A Level X Condition (3x6) MANOVA was performed on the dependent measures of segmental lag and velocity difference (humerus, forearm, hand). Coefficients of variation for segmental lag served to identify possible critical values by determining pattern variability. Three-dimensional scatterplots were used to help visualize pattern variation and stability of segmental lag within a movement space. Results of this study indicate that increasing the ratio of ball diameter to hand length is a control parameter that changes throwing patterns. The data indicate that when the ratio of hand length to ball diameter reached .74 throwing patterns changed. The lack of significance for coefficients of variance indicated that a critical value was not supported. Changes in pattern were best defined by changes in the relative position of forearm lag irrespective of level and condition. A change in humeral lag was important only to those throwers that took full advantage of the open kinetic chain. Hand lag remained generally constant across conditions and levels. In fact, only the most mature throwers exhibited a change from positive to negative lag with an increase in hand to ball diameter ratio. Increasing the hand to ball ratio changes the throwing pattern at a ratio between .86 and .74. When change occurs throwers are still attempting to take advantage of the open kinetic chain by maintaining as much distal lag as possible. The lag that is sacrificed most often is positive lag between the forearm and humerus. On a practical basis, care should be taken to insure that the size of the ball is appropriate for the throwers hand if positive change in throwing pattern is the goal of practice.

Page generated in 0.0663 seconds