• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 424
  • 363
  • 89
  • 44
  • 21
  • 15
  • 15
  • 11
  • 9
  • 9
  • 8
  • 6
  • 5
  • 5
  • 4
  • Tagged with
  • 1223
  • 1223
  • 486
  • 315
  • 236
  • 208
  • 189
  • 187
  • 184
  • 168
  • 145
  • 143
  • 119
  • 98
  • 97
  • 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.
191

Coordination between heart rate variability and physical activity may be diminished by fatigability in non-older women in the hour before sleep / 非高齢女性では就寝前の心拍変動と身体活動の協働連関は疲労感により減衰する

Taniguchi, Kentaro 23 March 2022 (has links)
京都大学 / 新制・論文博士 / 博士(人間健康科学) / 乙第13483号 / 論人健博第9号 / 新制||人健||7(附属図書館) / 京都大学大学院医学研究科人間健康科学系専攻 / (主査)教授 藤井 康友, 教授 澤本 伸克, 教授 長尾 美紀 / 学位規則第4条第2項該当 / Doctor of Human Health Sciences / Kyoto University / DFAM
192

Effects of 8-Weeks of Isometric Handgrip Training on Resting Arterial Pressure

Millar, Philip J. 09 1900 (has links)
<p> Recent evidence has demonstrated that isometric handgrip training may improve resting arterial blood pressure. The current study evaluated the ability of simple, spring handgrips to reduce resting arterial blood pressure in normotensive participants using an 8-week randomized controlled design.</p> <p> Forty-nine (age: 66 ± 1) participants, 28 female and 21 males were recruited. All participants completed 5 pre-training sessions, used to familiarize and assess baseline blood pressure, heart rate and maximal hand strength. Maximal hand strength was assessed by three bilateral, maximal contractions with a hand dynamometer. Blood pressure and heart rate were assessed with an automated acquisition system. Participants were stratified to control and intervention groups based on baseline age and blood pressure by matched-pair randomization.</p> <p> Participants in the training condition (n = 25) completed 8 weeks of thrice weekly handgrip training at approximately 30% of their baseline maximal hand strength using a spring handgrip. Seated blood pressure and heart rate were assessed prior to each training session following 10 minutes of isolated rest. Training included 4, 2-minute contractions separated by 2 minutes of rest and completed bilaterally. Control participants (n = 24) completed weekly-seated measurements of blood pressure and heart rate following 10 minutes of isolated rest. Following 8 weeks of intervention all participants completed 3 sessions of post-training measurements.</p> <p> In trained participants, resting systolic and diastolic pressure decreased significantly from pre- to post- (SBP: 122 ± 3 mmHg to 112 ± 3 mmHg, DBP: 70 ± 1 mmHg to 67 ± 1 mmHg) while heart rate remained unaltered. Pulse pressure was significantly reduced with handgrip training, from 52 ± 3 mmHg to 45 ± 3 mmHg. Control participants demonstrated no changes in blood pressure, heart rate and pulse pressure, over the course of the study.</p> <p> In conclusion, spring handgrip training results in significant decreases in systolic, diastolic and pulse pressure. The mechanisms behind these improvements remain unknown and require further investigation.</p> / Thesis / Master of Science (MSc)
193

The Validity of Heart Rate and Accelerometry in the Assessment of Physical Activity in Pre-School Children

Hirji, A. January 1995 (has links)
The purpose of this study was to validate heart rate recording (Polar Vantage XL), and accelerometry (Tritrac-R3D) against a direct observational technique (BEACHES) in the assessment of physical activity in 49 healthy male and female pre-schoolers (3.0 to 5.9 yrs). Activity was assessed in a controlled laboratory environment and in 2 field trials during spontaneous uncontrolled activity. During the laboratory session, subjects wore a heart rate monitor and an accelerometer while performing a choreographed routine of activities. The actual level was coded concurrently on the BEACHES scale by a trained observer. The three measures were significantly correlated during the laboratory (r = 0.76-0.85) and field (r = 0.50-0.85) conditions. There was no difference in mean scores for activity level of the group between two different days of field observation, however, there was considerable intra-subject variability as reflected by the low to moderate rank order correlations for all techniques. It was found that a measurement interval of greater than 5 min would likely increase the correlations. These findings suggest that the three measures of PA provide similar information about the level of PA in both a controlled and the free play environment, and pre-school children as a group generally maintain a similar level of activity from day to day. / Thesis / Master of Science (MS)
194

The Effects of Obstructive Sleep Apnea Syndrome on Cardiovascular Function with Exercise Testing in Young Adult Males

Hargens, Trent Alan 06 March 2007 (has links)
Obstructive sleep apnea syndrome (OSAS) is a serious disorder that affects an estimated 24% of middle-age males, and 9% of middle-aged females. In addition, a large portion of individuals with OSAS go undiagnosed. OSAS is associated with several adverse health problems, including the metabolic syndrome. Therefore, there is a clear need to identify new methods for assessing OSAS risk. The exercise test has been used effectively as a diagnostic and prognostic tool for those at high risk for cardiovascular disease and hypertension. Research into the cardiopulmonary responses to exercise testing in young adult men with OSAS has not been examined. Objectives: The objectives of this study were to: 1) evaluate whether OSAS is characterized by exaggerated ventilatory responses to ramp exercise testing, with a secondary aim to evaluate if variations in serum leptin concentration might exert a regulatory in ventilatory responses during exercise; 2) To evaluate whether autonomic control of the cardiovascular response during exercise is distorted by OSAS in young overweight men, as manifested by a blunting of heart rate and exaggeration of blood pressure responses.; 3) To explore whether various simple clinical measures and response patterns from graded exercise testing might serve to discriminate between young men with and without OSAS. Methods: For objectives one and two, 14 obese men with OSAS [age = 22.4 ± 2.8; body mass index (BMI) = 32.0 ± 3.7; apnea-hypopnea index (AHI) = 22.7 ± 18.5], 16 obese men without OSAS (age = 21.4 ± 2.6; BMI = 31.4 ± 3.7), and 14 normal weight subjects (objective 2) (age = 21.4 ± 2.1; BMI = 22.0 ± 1.3) were recruited. For objective three, 91 men (age = 21.6 ± 2.8; AHI range = 0.6 – 60.5; BMI range = 19.0 – 43.9) were recruited. Subjects completed a ramp cycle ergometer exercise test, and a fasting blood sample was obtained to measure plasma leptin and blood lipid levels. Repeated measures ANOVA and stepwise linear regression was used to examine objectives 1 and 2. For objective 3, stepwise linear regression and receiver operator curve (ROC) analysis was utilized. Results: Ventilation (VE), the ventilatory equivalents for oxygen (VE/VO₂) and carbon dioxide (VE/VCO₂) were greater in the OSAS subjects vs. the overweight subjects without OSAS (P = 0.05, P < 0.05 and P < 0.005, respectively) at all exercise intensities. Heart rate (HR) recovery was attenuated in the overweight OSAS subjects compared to the No-OSAS and Control groups throughout 5 minutes of active recovery (P = 0.009). Oxygen uptake, HR, and blood pressure did not differ throughout exercise. Leptin was not associated with ventilatory responses at any exercise intensity. Linear regression analysis revealed hip-to-height ratio (HHR), hip circumference (HC), triglyceride levels, and recovery systolic blood pressure ratio (SBPR) at 2 and 4 minutes were independent predictors of AHI (model fit: R² = 0.68, p <0.0001). ROC analysis determined that percent body fat, HHR, and recovery HR at 2 minutes and 4 minutes were the best single predictors of OSAS risk (AUC = 0.77 for each measure, p = 0.003). Conclusions: Unique ventilatory and hemodynamic characteristics to maximal exercise testing are exhibited in young men with OSAS. These characteristics may be related to alterations in the sympathetic nervous system and chemoreceptor activation, and may be early clinical signs in the progression of OSAS. These exercise characteristics, along with anthropometric and body composition measures may provide useful information in identifying young men at risk for OSAS. / Ph. D.
195

Aerobic Exercise Training and Nasal CPAP Therapy: Adaptations in Cardiovascular Function in Patients with Obstructive Sleep Apnea

Kaleth, Anthony Scott 30 July 2002 (has links)
Obstructive sleep apnea (OSA) is a serious disorder that affects up to 24% of middle-aged males. The substantial cost and inconvenience associated with polysomnography limits the number of people who seek treatment. Therefore, information concerning exercise tolerance and hemodynamic function in obstructive sleep apnea (OSA) patients may add new and clinically meaningful information to the process of grading disease severity and/or assessing treatment outcomes. Objectives: The primary objective of this study was to explore relationships between polysomnography (PSG) markers of sleep function and resting and exercise measures of hemodynamic function in patients diagnosed with mild-to-severe OSA. A family of clinical markers including heart rate (HR), blood pressure (BP), cardiac index (CI), stroke volume index (SVI), total peripheral resistance (TPR), and oxygen uptake (VO2) were assessed in this study. A second objective was to explore differences in hemodynamic function at rest and during graded exercise in OSA patients versus control subjects matched for age and body mass index (BMI). A final objective was to evaluate the extent that treatment with nCPAP alone, or combined with a moderate aerobic exercise training program impacted markers of hemodynamic function (results not reported here). Methods: Eleven newly diagnosed OSA patients [5 male, 6 female; age: 46.5 + 12.0 yrs; respiratory disturbance index (RDI) = 30.2 + 15.0] and 10 apparently healthy control subjects (4 male, 6 female; age: 39.8 + 6.9 yrs) completed daytime resting measurements of heart rate variability (HRV) and blood pressure (BP); and underwent a maximal cycle ergometer exercise test at baseline and 6 wk post-treatment initiation. Pearson product moment correlations were calculated between PSG markers of sleep function and: (1) daytime measures of HRV; (2) BP; and (3) submaximal and peak exercise measures of hemodynamic function. Independent t tests were used to explore differences between OSA patients and controls. Results: Stage 1 sleep duration was significantly related to daytime SBP (r = 0.69; P < 0.05) and MAP (r = 0.72; P < 0.05). Daytime MAP (P = 0.01) and DBP (P = 0.02) were significantly different between groups. Exercise testing yielded the following results: RDI was significantly related to HR at 60 watts (r = -0.70; P = 0.02) and 100 watts (r = -0.69; P = 02); stage 2 sleep duration was inversely related to CI at 60 (r = -0.76; P = 0.03) and 100 watts. In addition, stage 1 sleep duration was significantly correlated with TPR at 60 watts (r = 0.70; P = 0.06) and 100 watts (r = 0.71; P = 0.05). At peak exercise, a significant relationship was noted between peak HR and stage 2 sleep duration (r = -0.73; P = 0.02); and RDI (r = -0.66; P = 0.03). Furthermore, relative VO2pk was positively correlated to REM sleep duration (r = 0.62; P = 0.04). Conclusions: Distinct patterns exist in measures of daytime HRV and BP may provide physicians unique and clinically useful information. In addition, peak exercise capacity is reduced in the OSA patient and may be related to a blunted HR response to graded exercise. / Ph. D.
196

Athlete Monitoring in American Collegiate Football

Lewis, Marc Theron 17 March 2021 (has links)
American football is one of the most popular sports in the United States. However, in comparison to other mainstream sports such as soccer and rugby, there is limited literature using scientific principles and theory to examine the most appropriate ways to monitor the sport. This serves as a barrier to American football practitioners in their development and implementation of evidence-based sport preparation programs. Therefore, the primary aim of this line of research (i.e., dissertation) is to illustrate the efficacy of commonly used athlete monitoring tools within the sport of American collegiate football, while proposing a systematic framework to guide the development of an athlete monitoring program. This aim was achieved through a series of studies with the following objectives: 1) to quantify the physical demands of American collegiate football practice by creating physiological movement profiles through the use of integrated microtechnology metrics and heart rate indices, 2) to determine the positional differences in the physical practice demands of American collegiate football athletes, 3) to examine which integrated microtechnology metrics might be used to most efficiently monitor the training load of American collegiate football athletes, 4) to demonstrate the suitability of using the countermovement jump (CMJ) to assess training adaptations in American collegiate football athletes through examining weekly changes in CMJ performance over the course of two 4-week periodized training blocks (8 weeks total), and 5) to examine the effect of acute fatigue on CMJ performance in American football athletes. The first study from this line of research quantified the physical demands of American collegiate football by position groups and found significant differences in both running based and non-running based training load metrics. In addition, the first study utilized a principal component analysis to determine 5 'principal' components that explain approximately 81% of the variance within the data. The second study utilized a univariate analysis and found significant changes in CMJ performance due the effect of time with significant improvements in CMJ 'strategy' variables over the training period. Finally, the third study used effects sizes to illustrate a larger magnitude of change in CMJ 'strategy' variables than CMJ 'output' variables due to effect of acute fatigue. Results from studies 2 and 3 suggest the importance of monitoring CMJ strategy variables when monitoring training adaptations and fatigue in American collegiate football athletes. This line of research provides practitioners with a systematic framework through which they can develop and implement evidence-based sport preparation programs within their own organizational context. In addition, this line of research provides practitioners with recommendations for which metrics to monitor when tracking training load in American collegiate football using integrated microtechnology. Finally, this line of research demonstrates how to assess training adaptations and fatigue using the CMJ within the sport of American collegiate football, while providing an empirical base through which the selection of CMJ variables can take place. Collectively, this line of research uses scientific principles and theory to extend the current literature in American collegiate football, while providing practitioners with a guide to athlete monitoring within the sport. / Doctor of Philosophy / American football is one the most popular sports in the United States. Despite its popularity, there is limited research using scientific principles and theories to examine ways to most effectively monitor the sport. Broadly, athlete monitoring refers to the process of providing informational feedback from the athlete to practitioners. This allows practitioners to make decisions informed by data. Therefore, this line of research (i.e. dissertation) aimed to use a variety of commonly used athlete monitoring tools to monitor American collegiate football athletes, while proposing a framework to guide in the development of an athlete monitoring program. This line of research consisted of a series of 3 studies. In study #1, it was found that integrated microtechnology units and heart rate sensors could be used to determine the physical demands of American collegiate football practice, as well as differences in the physical demands of practice by position group. In addition, a set of 5 training load constructs were found through which training load in American collegiate football athletes may be appropriately monitored. In study #2, it was found that countermovement jump (CMJ) strategy variables indicating how the jump occurred may provide more insight into strength and power training adaptations than CMJ output variables that indicate what occurred as a result of the jump in this highly trained athletic population. Finally, in study #3, it was found that CMJ strategy variables may be more sensitive to acute fatigue from a football-specific training session than CMJ output variables in American collegiate football athletes. Collectively, this research suggest that integrated microtechnology units, heart rate sensors, and the CMJ using a force testing platform may be used to monitor American collegiate football athletes. Moreover, this research suggests which variables to utilize when monitoring this population using these tools through the proposed athlete monitoring framework.
197

Use of Cross-Correlation Analysis to Determine Heart Rate Kinetics During Non-Steady State, Fatiguing Exercise in Collegiate Female Soccer Athletes

Williams, Brian Orbreyn 01 July 2020 (has links)
For years, heart rate (HR) kinetics have been used as an indicator of training status and fatigue. Slowed kinetics indicate poor fitness and/or fatigue. In this study it was determined that HR kinetics can be reliably estimated during modeled, quasi-binary, and dynamic exercise using cross-correlation analysis of HR and external work rate. Heart rate and running speed were cross-correlated yielding a cross-correlation function (CCF) and analyzed for its peak (CCFmax) and time delay (CCFlag). Modeled exercise data where the time constants for HR (τ) increased from 2-120 sec. yielded linear decreases in CCFmax (r2 = 0.9949) and linear increases in CCFlag (r2=0.9996). A strong linear relationship existed between CCFmax and CCFlag (r2=0.9989). Steady-state exercise data produced strong relationships between the calculated τ and CCFmax (r2=0.8736) and CCFlag (r2=0.9061), and CCFmax and CCFlag showed a positive relationship (r2=0.7753). CCFmax between repeated sprint trials (R2=0.9123) and super set trails (R2=0.9227) were very similar. These results suggest good repeatability for both quasi-binary activity and random activity. To assess validity, CCFmax values during the sprint trials were compared to two standard field tests of fitness (Beep and Man U tests). There were strong relationships between CCFmax and distances covered during the Beep (r2=0.7911) and Mann U tests (r2=0.7770). Lastly, the applicability of the CCF method was applied to dynamic exercise, using data collected from competitive soccer matches. For the field players, significant reductions in CCFmax occurred during the first and second periods of the match. There was a significant relationship between the total distance covered during the match and the decline in CCFmax (r=-0.4297, p<0.05). Larger declines in CCFmax during the last 15 min of the match were also seen in the second match of a multiple match week compared to the first match. Tis later finding suggests that CCFmax may be a use tool to evaluate "fatigue" during dynamic exercise. Overall, cross-correlation of HR and running speed appears to be a reliable, valid and applicable approach to evaluate HR kinetics during exercise. As such, it may be beneficial for evaluating player fitness and readiness for competition. / Doctor of Philosophy / Exercise physiologists and sports professionals are continually in search of novel techniques which would assess training effectiveness and performance on the field. However, it is of paramount importance that any field-based data collection method must be noninvasive as to not interfere with the athlete's ability to perform in sport. Currently, heart rate (HR) is the most readily accessible and commonly used variable to estimate cardiovascular response to exercise. Heart rate kinetics have proven to be a powerful indicator of training status as HR responses to changes in exercise intensity are accelerated following exercise training. In this study we were able to determine that HR kinetics can be reliably estimated during modeled, quasi-binary, and dynamic exercise using cross-correlation analysis of HR and external work rate. Heart Rate and running speed were cross-correlated yielding a cross-correlation function (CCF). That function was then analyzed for its peak (CCFmax) and time delay (CCFlag). Modeled exercise data yielded linear decreases in CCFmax and linear increases in CCFlag. Also, CCFmax and CCFlag were correlated to each other. Steady-state exercise data produced the same linear relationships observed for the modeled data for CCFmax and CCFlag. CCFmax between repeated sprint trials were found to be highly reliable which suggest good repeatability for both quasi-binary activity and random activity. CCFmax was also found to be highly valid when comparing sprint values to validated fitness test values. Additionally, good relationships were found between CCFmax derived during fitness tests and distances covered on the fitness tests. As HR kinetics are linked to fitness, these results suggest that CCFmax values are valid. There was a significant relationship between the total distance covered during a full soccer match and the decline in CCFmax in field players that were not seen in the goalkeeper. Lastly, CCFmax declined during the last 15 minutes of the match compared to the start of the match. These results demonstrate CCF derived HR kinetics appear to be reliable and valid metrics for evaluating soccer fitness and "fatigue". This method may prove to be a strong indicator of fitness in other high activity sports as well.
198

Using Pressure Transducers for Noninvasive Heart and Respiratory Monitoring

Dowden, Matthew Richard Barcroft 24 August 2012 (has links)
Detecting heart and respiratory rates is an essential means of providing emergency medical care. Current methods of detecting such signals include the widely used electrocardiography (ECG) method. Other more manual methods of heart and respiratory rate estimation require a practitioner to constantly observe the patient. These methods are time consuming and detract valuable time from emergency medical care. This thesis presents a novel, hands off, heart and respiratory monitor (HARMONI). It uses pressure transducers and medical tubing placed on a person's chest. The tubing is plugged off at one end, and then attached to a pressure transducer at the other end. The transducer sees spikes in voltage whenever the pressure inside the tubing changes. Heart and respiratory rates both cause expansion in the chest, increasing the pressure in the tubing, and causing the transducer to see a change in voltage. The method was first validated, and then tested in a simulated environment. Finally, the device was transformed in to a full system prototype. Human tests were conducted to correlate the signal with that of an industry standard ECG device. This thesis explains how heart and respiratory rates can be derived using signal processing techniques and a simple non-invasive sensor. This device is a rapidly deployable tool that has the potential to save lives specifically in mass casualty situations. It would be a force multiplier, allowing a single responder to monitor multiple casualties, saving time and lives. / Master of Science
199

Relating Heart Rate Variability, Urinary Catecholamines, and Baseline Fitness to Respiratory Distress Index and Severity of Disease in Obstructive Sleep Apnea Patients

Ballentine, Howard Monroe 21 August 2001 (has links)
Heart Rate Variability (HRV) currently is utilized when assessing the risk of mortality in individuals suffering from coronary heart disease or diabetic neuropathy. Research has shown that patients with Obstructive Sleep Apnea (OSA) also show a decrease in HRV, as well as an increase in sympathetic drive characterized by an increase in the low-frequency component of HRV. HRV, in conjunction with other indicators, may represent a non-invasive, low cost method for the confirmation of severity of OSA in some patients and therefore may represent an additional tool for the assessment of risk in these individuals. This becomes especially true when urinary catecholamines, fitness level, and quality of life (QOL) assessment are included. The purpose of this study was to determine if a correlation exists between severity of OSA as assessed by respiratory distress index (RDI) and the selected measures HRV, fitness, QOL, and catecholamine output. Subjects were 6 men and 5 women who were recently diagnosed with OSA by polysomnographic (PSG) study. HRV and blood pressure was measured during two consecutive trials consisting of 512 heartbeats. Catecholamine levels were determined by HPLC following 24-hour urine collection. Fitness levels were established following cycle ergometer testing and QOL following questionnaire completion. Subjects with lower weight, BMI, and neck circumference had significantly higher parasympathetic influence as analyzed through the amount of high frequency component of HRV (r =.738, .726, .789, respectively; p<0.05). Respiratory distress index (RDI) was negatively related to the average heart rate (HR=RR average, r = -.610, p<0.05), while the amount of total sleep (r = .657, p<0.05) and REM sleep (r = .739, p<0.01) increased as HR increased. The average HR was correlated to the predicted VO2max (r = .677, p<0.05). When the frequency components of HRV, fitness, QOL, and catecholamines were combined, the association to RDI increased dramatically (r = .984, p = .02). The results indicate that as the severity of OSA increases, markers of fitness, QOL, and sleep decrease. There is also an inverse relationship between autonomic function and severity of OSA. It is concluded that HRV and fitness levels are inversely related to the severity of OSA, and that these measures may be developed into a risk assessment tool for use in OSA patient evaluatio / Master of Science
200

Young Adults' Social Interest in Complex Film Clips: Impact of Autism Characteristics

Lorenzi, Jill Elizabeth 18 May 2015 (has links)
Deficits in social functioning in individuals with autism spectrum disorder (ASD) may be explained in part by the limited salience of or reward value associated with the social world, relative to individuals with typical development (e.g., Jones and Klin, 2008; Mundy, 1995; Mundy and Neal, 2005). However, despite many calls for the use of ecologically valid, rich, complex stimuli when investigating deficits in social attention and interest in ASD, few studies have adopted these recommendations. The current study investigated social interest in a non-clinical college student population (n = 78; 72% female; M age = 20.41 years) by analyzing participants' verbal descriptions of dynamic film clips. It was predicted that as level of self-reported ASD characteristics increased, proportions of verbal descriptions devoted to higher-level social information (e.g., relationships, mental or emotional states) would decrease, while holding self-reported social anxiety, autonomic flexibility (i.e., heart rate variability), and verbal ability constant. In other words, self-reported ASD characteristics were hypothesized to impact social interest above and beyond the effects of other predicted covariates. Results, however, did not reveal significant differences in social interest across varying levels of ASD characteristics, and neither social anxiety nor autonomic flexibility served as a moderator of this association. Variations of the current study and the inclusion of a clinical population are discussed as possible future directions to refine the study and better target intervention efforts aimed at ameliorating social deficits in ASD. / Ph. D.

Page generated in 0.1041 seconds