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Search Results: 1 - 10 of 329876 matches for " Timothy S Church "
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Heart Rate Variability Characteristics in Sedentary Postmenopausal Women Following Six Months of Exercise Training: The DREW Study
Conrad P. Earnest, Carl J. Lavie, Steven N. Blair, Timothy S. Church
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0002288
Abstract: Background Decreased heart rate variability (HRV) is associated with a higher risk of mortality. Overall, postmenopausal women have lower levels of HRV than premenopausal women, which may be additionally complicated by lifestyle related behaviors such as physical inactivity and obesity. Though cardiorespiratory exercise training increases HRV, little is known regarding the exercise dose necessary to promote this improvement. Methodology/Principal Findings Our primary aim was to measure HRV in post-menopausal women following 6-months of exercise training. We examined supine resting HRV in 373 post-menopausal women (45–75 y) after 6-months of randomly assigned and double-blinded administered exercise training exercise training at 50%, 100% and 150% of the NIH Consensus Development Panel's recommended minimal physical activity level. This corresponded to 4, 8, or 12 kcal/kg per week (KKW) of energy expenditure. At baseline, we observed no significant differences in HRV or hormone replacement use between treatment groups. However, we did observe that Caucasian women and those taking antidepressant medications had lower levels of baseline HRV. After 6-months of exercise intervention, we observed a dose dependent increase in all parasympathetically derived time and frequency domain measurements across exercise groups after adjustment for age, ethnicity, antidepressants, and baseline rMSSD (all, P<0.001). For example, the parasympathetic index rMSSD was greater than control (23.19±1.0) for the 4-KKW (25.98±0.8; P = 0.14), 8-KKW (27.66±1.0; P<0.05), and 12-KKW (27.40±0.0; P<0.05) groups at follow-up. Conclusions/Significance Moderate intensity exercise training exercise is sufficient to improve HRV in previously sedentary postmenopausal women in a dose-dependent manner, as 4-KKW is insufficient to improve parasympathetic indices of HRV, while 12-KKW conferred no greater improvement than 8-KKW. Trial Registration Clinicaltrials.gov NCT 00011193
Associations between Cardiorespiratory Fitness and Health-Related Quality of Life
Robert A Sloan, Susumu S Sawada, Corby K Martin, Timothy Church, Steven N Blair
Health and Quality of Life Outcomes , 2009, DOI: 10.1186/1477-7525-7-47
Abstract: A total of 709 males (18–49 yr) performed a submaximal exercise test and HRQOL assessment (SF-12v2?) between 2004–2006. CRF level was classified into fourths depending on age distribution with the lowest fitness quartile serving as the referent group. PCS and MCS scores ≥ 50 were defined as above the norm. Logistic regression was used to obtain odds ratios (OR) and 95% confidence intervals (CI). ResultsThe age-standardized prevalence of above the norm scores was lowest in the referent CRF quartile, PCS 56.6% and MCS 45.1%. After adjusting for age, systolic blood pressure, body mass index, smoking habit, alcohol habit and using the lowest CRF group as the reference, the OR (95% CI) for PCS scores above the norm across the fitness quartiles (P < 0.003 for trend) were 1.51(0.94–2.41), 2.24(1.29–3.90), and 2.44 (1.30–4.57); For MCS the OR (95% CI) were across the fitness quartiles (P trend < 0.001) 2.03(1.27–3.24), 4.53(2.60–7.90), 3.59(1.95–6.60).Among males in the United States Navy relative higher levels of CRF are associated with higher levels of HRQOL.The Centers for Disease Control and Prevention and the Agency for Healthcare Research and Quality consider the surveillance of mental and physical health to be imperative in understanding health-related quality of life (HRQOL) and its impact on increasing the quality and years of healthy life, eliminating health disparities, and predicting future medical health care costs [1,2]. Higher levels of cardiorespiratory fitness (CRF) have been shown to be associated with higher levels of HRQOL in the older and chronically diseased populations [3,4]. However, there is a dearth of evidence on the association of CRF level and HRQOL in apparently healthy young adults. A recent systematic review highlighted the public health importance of better understanding the relation between physical activity and HRQOL in the general adult population [5]. Specifically, the authors noted that cross-sectional studies demonstrated positive asso
Cardiac rehabilitation and exercise therapy in the elderly: Should we invest in the aged?

Arthur R Menezes,Carl J Lavie,Richard V Milani,Ross A Arena,Timothy S Church,

老年心脏病学杂志(英文版) , 2012,
Abstract: Coronary heart disease (CHD) is the leading cause of death worldwide and becomes increasingly prevalent among patients aged 65 years and older. Elderly patients are at a higher risk for complications and accelerated physical deconditioning after a cardiovascular event, especially compared to their younger counterparts. The last few decades were privy to multiple studies that demonstrated the beneficial effects of cardiac rehabilitation (CR) and exercise therapy on mortality, exercise capacity, psychological risk factors, inflammation, and obesity among patients with CHD. Unfortunately, a significant portion of the available data in this field pertains to younger patients. A viable explanation is that older patients are grossly underrepresented in these programs for multiple reasons starting with the patient and extending to the physician. In this article, we will review the benefits of CR programs among the elderly, as well as some of the barriers that hinder their participation.
Changes in Weight, Waist Circumference and Compensatory Responses with Different Doses of Exercise among Sedentary, Overweight Postmenopausal Women
Timothy S. Church, Corby K. Martin, Angela M. Thompson, Conrad P. Earnest, Catherine R. Mikus, Steven N. Blair
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0004515
Abstract: Background It has been suggested that exercise training results in compensatory mechanisms that attenuate weight loss. However, this has only been examined with large doses of exercise. The goal of this analysis was to examine actual weight loss compared to predicted weight loss (compensation) across different doses of exercise in a controlled trial of sedentary, overweight or obese postmenopausal women (n = 411). Methodology/Principal Findings Participants were randomized to a non-exercise control (n = 94) or 1 of 3 exercise groups; exercise energy expenditure of 4 (n = 139), 8 (n = 85), or 12 (n = 93) kcal/kg/week (KKW). Training intensity was set at the heart rate associated with 50% of each woman's peak VO2 and the intervention period was 6 months. All exercise was supervised. The main outcomes were actual weight loss, predicted weight loss (exercise energy expenditure/ 7700 kcal per kg), compensation (actual minus predicted weight loss) and waist circumference. The study sample had a mean (SD) age 57.2 (6.3) years, BMI of 31.7 (3.8) kg/m2, and was 63.5% Caucasian. The adherence to the intervention was >99% in all exercise groups. The mean (95% CI) weight loss in the 4, 8 and 12 KKW groups was ?1.4 (?2.0, ?0.8), ?2.1 (?2.9, ?1.4) and ?1.5 (?2.2, ?0.8) kg, respectively. In the 4 and 8 KKW groups the actual weight loss closely matched the predicted weight loss of ?1.0 and ?2.0 kg, respectively, resulting in no significant compensation. In the 12 KKW group the actual weight loss was less than the predicted weight loss (?2.7 kg) resulting in 1.2 (0.5, 1.9) kg of compensation (P<0.05 compared to 4 and 8 KKW groups). All exercise groups had a significant reduction in waist circumference which was independent of changes in weight. Conclusion In this study of previously sedentary, overweight or obese, postmenopausal women we observed no difference in the actual and predicted weight loss with 4 and 8 KKW of exercise (72 and 136 minutes respectively), while the 12 KKW (194 minutes) produced only about half of the predicted weight loss. However, all exercise groups had a significant reduction in waist circumference which was independent of changes in weight. Trial Registration ClinicalTrials.gov NCT 00011193
Microencapsulated foods as a functional delivery vehicle for omega-3 fatty acids: a pilot study
Conrad P Earnest, Molly K Hammar, Monica Munsey, Catherine R Mikus, Robert M David, J Alexander Bralley, Timothy S Church
Journal of the International Society of Sports Nutrition , 2009, DOI: 10.1186/1550-2783-6-12
Abstract: Consumption of oily fish or oils rich in the omega-3 fatty acids (N3) docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are well established for their role in supporting cardiovascular health [1-3]. While the mechanisms surrounding the cardioprotective effects of EPA and DHA are complex, they can be broadly categorized into modulations of cardiac function (including antiarrhythmic effects), hemodynamics (cardiac mechanics), arterial endothelial function, and the modulation of lipids, in particular triacylglycerols [2,4].Despite these benefits the actual intake of fish derived N3 is relatively small in the United States whereby total N3 accounts for 1.6 g/d (0.7% of energy intake). Of this, about 1.4 g/d is plant derived α-linolenic acid (ALA), whereas only 0.1 to 0.2 g/d comes from EPA and DHA [2]. Supplementation with N3 capsules is an option; however, gastrointestinal disturbances and fish odor often contribute to low compliance. Moreover, little research has been performed on younger, healthy and active participants at low risk for cardiovascular disease. It is intuitive, however, that early prophylaxis via the ingestion of N3 while young is beneficial for long term health. The aim of our investigation was to perform a pilot trial to test the feasibility of using foods fortified with microencapsulated fish oil (MicroN3) to deliver a beneficial daily amount of EPA and DHA to individuals not regularly consuming fish or N3 supplement products.We obtained written informed consent from 20 participants (12 men, and 8 women; 20–70 y) in generally good health, who agreed to maintain their current diet and exercise habits (3–5 days/wk) during the trial. Participants were excluded if their BMI was <18.5 or >34.9. We also excluded candidates currently taking an N3 supplement or eating fish > 1×/wk. Participants were randomized equally to a treatment or placebo group after completing all questionnaires inclusive of food frequency measurements. On days 0 and 15 blood
Determinants of the Changes in Glycemic Control with Exercise Training in Type 2 Diabetes: A Randomized Trial
Neil M. Johannsen, Lauren M. Sparks, Zhengyu Zhang, Conrad P. Earnest, Steven R. Smith, Timothy S. Church, Eric Ravussin
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0062973
Abstract: Aims To assess the determinants of exercise training-induced improvements in glucose control (HbA1C) including changes in serum total adiponectin and FFA concentrations, and skeletal muscle peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) protein content. Methods A sub-cohort (n = 35; 48% men; 74% Caucasian) from the HART-D study undertaking muscle biopsies before and after 9 months of aerobic (AT), resistance (RT), or combination training (ATRT). Results Changes in HbA1C were associated with changes in adiponectin (r = ?0.45, P = 0.007). Participants diagnosed with type 2 diabetes for a longer duration had the largest increase in PGC-1α (r = 0.44, P = 0.008). Statistical modeling examining changes in HbA1C suggested that male sex (P = 0.05), non-Caucasian ethnicity (P = 0.02), duration of type 2 diabetes (r = 0.40; P<0.002) and changes in FFA (r = 0.36; P<0.004), adiponectin (r = ?0.26; P<0.03), and PGC-1α (r = ?0.28; P = 0.02) explain ~65% of the variability in the changes in HbA1C. Conclusions Decreases in HbA1C after 9 months of exercise were associated with shorter duration of diabetes, lowering of serum FFA concentrations, increasing serum adiponectin concentrations and increasing skeletal muscle PGC-1α protein expression. Trial Registration ClinicalTrials.gov NCT00458133
The Effect of Exercise Training Modality on Serum Brain Derived Neurotrophic Factor Levels in Individuals with Type 2 Diabetes
Damon L. Swift, Neil M. Johannsen, Valerie H. Myers, Conrad P. Earnest, Jasper A. J. Smits, Steven N. Blair, Timothy S. Church
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0042785
Abstract: Introduction Brain derived neurotrophic factor (BDNF) has been implicated in memory, learning, and neurodegenerative diseases. However, the relationship of BDNF with cardiometabolic risk factors is unclear, and the effect of exercise training on BDNF has not been previously explored in individuals with type 2 diabetes. Methods Men and women (N = 150) with type 2 diabetes were randomized to an aerobic exercise (aerobic), resistance exercise (resistance), or a combination of both (combination) for 9 months. Serum BDNF levels were evaluated at baseline and follow-up from archived blood samples. Results Baseline serum BDNF was not associated with fitness, body composition, anthropometry, glucose control, or strength measures (all, p>0.05). Similarly, no significant change in serum BDNF levels was observed following exercise training in the aerobic (?1649.4 pg/ml, CI: ?4768.9 to 1470.2), resistance (?2351.2 pg/ml, CI:?5290.7 to 588.3), or combination groups (?827.4 pg/ml, CI: ?3533.3 to1878.5) compared to the control group (?2320.0 pg/ml, CI: ?5750.8 to 1110.8). However, reductions in waist circumference were directly associated with changes in serum BDNF following training (r = 0.25, p = 0.005). Conclusions Serum BDNF was not associated with fitness, body composition, anthropometry, glucose control, or strength measures at baseline. Likewise, serum BDNF measures were not altered by 9 months of aerobic, resistance, or combination training. However, reductions in waist circumference were associated with decreased serum BDNF levels. Future studies should investigate the relevance of BDNF with measures of cognitive function specifically in individuals with type-2 diabetes.
Effect of Different Doses of Aerobic Exercise on Total White Blood Cell (WBC) and WBC Subfraction Number in Postmenopausal Women: Results from DREW
Neil M. Johannsen, Damon L. Swift, William D. Johnson, Vishwa D. Dixit, Conrad P. Earnest, Steven N. Blair, Timothy S. Church
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0031319
Abstract: Background Elevated total white blood cell (WBC) count is associated with an increased risk of coronary heart disease and death. Aerobic exercise is associated with lower total WBC, neutrophil, and monocyte counts. However, no studies have evaluated the effect of the amount of aerobic exercise (dose) on total WBC and WBC subfraction counts. Purpose To examine the effects of 3 different doses of aerobic exercise on changes in total WBC and WBC subfraction counts and independent effects of changes in fitness, adiposity, markers of inflammation (IL-6, TNF-α, C-reactive protein), fasting glucose metabolism, and adiponectin. Methods Data from 390 sedentary, overweight/obese postmenopausal women from the DREW study were used in these analyses. Women were randomized to a non-exercise control group or one of 3 exercise groups: energy expenditure of 4, 8, or 12 kcal kg?1?week?1 (KKW) for 6 months at an intensity of 50% VO2peak. Results A dose-dependent decrease in total WBC counts (trend P = 0.002) was observed with a significant decrease in the 12KKW group (?163.1±140.0 cells/μL; mean±95%CI) compared with the control (138.6±144.7 cells/μL). A similar response was seen in the neutrophil subfraction (trend P = 0.001) with a significant decrease in the 12KKW group (?152.6±115.1 cells/μL) compared with both the control and 4KKW groups (96.4±119.0 and 21.9±95.3 cells/μL, respectively) and in the 8KKW group (?102.4±125.0 cells/μL) compared with the control. When divided into high/low baseline WBC categories (median split), a dose-dependent decrease in both total WBCs (P = 0.003) and neutrophils (P<0.001) was observed in women with high baseline WBC counts. The effects of exercise dose on total WBC and neutrophil counts persisted after accounting for significant independent effects of change in waist circumference and IL-6. Conclusion Aerobic exercise training reduces total WBC and neutrophil counts, in a dose-dependent manner, in overweight/obese postmenopausal women and is especially beneficial for those with systemic low grade inflammation. Clinical Trials Identifier: NCT00011193
Trends over 5 Decades in U.S. Occupation-Related Physical Activity and Their Associations with Obesity
Timothy S. Church,Diana M. Thomas,Catrine Tudor-Locke,Peter T. Katzmarzyk,Conrad P. Earnest,Ruben Q. Rodarte,Corby K. Martin,Steven N. Blair,Claude Bouchard
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0019657
Abstract: The true causes of the obesity epidemic are not well understood and there are few longitudinal population-based data published examining this issue. The objective of this analysis was to examine trends in occupational physical activity during the past 5 decades and explore how these trends relate to concurrent changes in body weight in the U.S.
High-Order SNP Combinations Associated with Complex Diseases: Efficient Discovery, Statistical Power and Functional Interactions
Gang Fang, Majda Haznadar, Wen Wang, Haoyu Yu, Michael Steinbach, Timothy R. Church, William S. Oetting, Brian Van Ness, Vipin Kumar
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0033531
Abstract: There has been increased interest in discovering combinations of single-nucleotide polymorphisms (SNPs) that are strongly associated with a phenotype even if each SNP has little individual effect. Efficient approaches have been proposed for searching two-locus combinations from genome-wide datasets. However, for high-order combinations, existing methods either adopt a brute-force search which only handles a small number of SNPs (up to few hundreds), or use heuristic search that may miss informative combinations. In addition, existing approaches lack statistical power because of the use of statistics with high degrees-of-freedom and the huge number of hypotheses tested during combinatorial search. Due to these challenges, functional interactions in high-order combinations have not been systematically explored. We leverage discriminative-pattern-mining algorithms from the data-mining community to search for high-order combinations in case-control datasets. The substantially improved efficiency and scalability demonstrated on synthetic and real datasets with several thousands of SNPs allows the study of several important mathematical and statistical properties of SNP combinations with order as high as eleven. We further explore functional interactions in high-order combinations and reveal a general connection between the increase in discriminative power of a combination over its subsets and the functional coherence among the genes comprising the combination, supported by multiple datasets. Finally, we study several significant high-order combinations discovered from a lung-cancer dataset and a kidney-transplant-rejection dataset in detail to provide novel insights on the complex diseases. Interestingly, many of these associations involve combinations of common variations that occur in small fractions of population. Thus, our approach is an alternative methodology for exploring the genetics of rare diseases for which the current focus is on individually rare variations.
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