Biomedical subjects

Timothy S Church

Publications and source records attributed to Timothy S Church.

At least 19 recordsLinked to original sources

PubMed2006

Coronary artery calcium score, risk factors, and incident coronary heart disease events.

BACKGROUND: Whether the absence of coronary artery calcium, or conversely the presence of high volumes of coronary artery calcium, may alter assessment of coronary heart disease risk based on traditional risk factors is uncertain. We sought to identify a potential threshold of coronary artery calcium for clinical use and examine the predictive power of coronary artery calcium in individuals categorized using conventional coronary heart disease risk assessment. METHODS: The study included 10,746 men and women (36.3%) with a mean age of 53.8+/-9.9 years who were either physician- or self-referred for electron beam tomography scanning to a preventive medical clinic. Coronary heart disease risk factors were elicited by use of a questionnaire. RESULTS: During a mean follow-up of 3.5 years, 81 primary events (coronary heart disease death or nonfatal myocardial infarction) occurred. Among individuals with a coronary artery calcium score of zero, the primary event rate was very low (0.4 events per 1000 person-years of observation). When participants were stratified by self-reported coronary heart disease risk factors (0-2, or 3-4), a coronary artery calcium score >or=100 was associated with substantially increased risk of coronary heart disease events within each level of stratification. In a subgroup of participants with available clinical data, similar results were found when participants were categorized by Framingham risk scores. CONCLUSIONS: Coronary artery calcium score can identify individuals at increased risk for coronary heart disease events who otherwise would be considered low-risk based on clinical assessment. A coronary artery calcium score of zero is associated with very low risk for coronary heart disease in the short to intermediate term ( approximately 3.5 years) regardless of the number of risk factors present.

Adult↗

PubMed2006

Coronary artery calcium, exercise tolerance, and CHD events in asymptomatic men.

Coronary artery calcium (CAC) scores >/=100 are predictive of CHD events in asymptomatic men. Exercise tolerance of >/=10METs predicts lower event rates in CHD patients; however, its relationship with events in individuals with subclinical atherosclerosis is less known. Participants were 710 asymptomatic men from the Aerobics Center Longitudinal Study whose exercise tolerance (ET) was quantified (<10 or >/=10METs) and whose CAC score was >/=100 as measured by electron beam tomography. During 3.5 years of follow-up 59 CHD events occurred. The age-adjusted hazard ratio (HR) of CHD events was 0.26 (95% CI=0.15-0.45) in men whose ET was >/=10METs compared with men whose ET was <10METs. Adjustment for CHD risk factors and abnormal exercise ECG did not change the association between ET and CHD. The extent of underlying atherosclerosis did not influence the association between ET and CHD; for example, the HR for CHD events in the >/=10MET group among men with CAC scores <400 and >/=400 was 0.16 (95% CI=0.05-0.56) and 0.23 (95% CI=0.11-0.46), respectively. In asymptomatic men with subclinical coronary atherosclerosis, an ET of >/=10METs identifies patients at lower risk for manifest CHD.

Calcium↗

PubMed2006

Visceral fat is an independent predictor of all-cause mortality in men.

OBJECTIVE: To examine the independent associations of abdominal fat (visceral and subcutaneous) and liver fat with all-cause mortality. RESEARCH METHODS AND PROCEDURES: Participants included 291 men [97 decedents and 194 controls; mean age, 56.4 +/- 12.0 (SD) years] who received a computed tomography (CT) examination at the preventive medicine clinic in Dallas, TX, between 1995 and 1999, with a mean mortality follow-up of 2.2 +/- 1.3 years. Abdominal fat was determined using contiguous CT images from the L3-L4 to L4-L5 intervertebral space. Liver fat was assessed using the CT-determined liver attenuation value, which is inversely related to liver fat. Logistic regression was used to determine the independent association between the fat depots and all-cause mortality. RESULTS: During the study, there were 97 deaths. Visceral fat [odds ratio (OR) per SD: 1.83; 95% CI: 1.23 to 2.73], abdominal subcutaneous fat (1.44; 1.02 to 2.03), liver fat (0.64; 0.46 to 0.87), and waist circumference (1.41; 1.01 to 1.98) were significant individual predictors of mortality after controlling for age and length of follow-up. In a model including all three fat measures (subcutaneous, visceral, and liver fat), age, and length of follow-up, only visceral fat (1.93; 1.15 to 3.23) was a significant predictor of mortality. DISCUSSION: Visceral fat is a strong, independent predictor of all-cause mortality in men.

Aged↗

PubMed2006

Association of cardiorespiratory fitness, body mass index, and waist circumference to nonalcoholic fatty liver disease.

BACKGROUND & AIMS: There is a need for more work examining the potential of physical activity and/or weight control as a preventive and/or therapeutic option in the treatment of fatty liver diseases. The purpose of this study was to examine the association between cardiorespiratory fitness, body mass index (BMI), and waist circumference with markers of nonalcoholic fatty liver disease (NAFLD). METHODS: Participants consisted of 218 apparently healthy nonsmoking, nonalcoholic men aged 33-73 years. Cardiorespiratory fitness was assessed by a maximal treadmill test. Liver and spleen density were measured using a computed tomography scan. We defined the presence of NAFLD as the following 3 conditions being met: (1) liver to spleen density of 1.0 or less, (2) serum alanine transaminase level greater than 30 U/L, and (3) serum aspartate transaminase/alanine transaminase level less than 1.0. RESULTS: Twenty-four (11%) of the participants met the NAFLD definition. There was an inverse association between fitness categories, and a positive association for BMI categories (and waist circumference categories) with the prevalence of NAFLD (P for trend <.001 for all). Fitness and BMI were independent of each other in their associations with the prevalence of NAFLD. The addition of waist circumference to the regression model attenuated the association with prevalence of NAFLD for both fitness (P value changed from <.0001 to .06) and BMI (P value changed from <.001 to .22). CONCLUSIONS: Fitness (inversely) and BMI (directly) were associated with the prevalence of NAFLD. However, these associations were attenuated when abdominal obesity was included in the statistical model.

Adult↗

PubMed2006

TREAD: TReatment with Exercise Augmentation for Depression: study rationale and design.

BACKGROUND: Despite recent advancements in the pharmacological treatment of major depressive disorder (MDD), over half of patients who receive treatment with antidepressant medication do not achieve full remission of symptoms. There is evidence that exercise can reduce depressive symptomatology when used as a treatment for MDD. However, no randomized controlled trials have evaluated exercise as an augmentation strategy for patients with carefully diagnosed MDD who remain symptomatic following an adequate acute phase trial of antidepressant therapy. PURPOSE: TReatment with Exercise Augmentation for Depression (TREAD) is an NIMH-funded, randomized, controlled trial designed to assess the relative efficacy of two doses of aerobic exercise to augment selective serotonin reuptake inhibitor (SSRI) treatment of MDD. METHODS: The TREAD study includes 12 weeks of acute phase treatment with a 12-week post-treatment follow-up. In addition to looking at change in depressive symptoms as a primary outcome, it also includes comprehensive assessment of psychosocial function and treatment adherence. RESULTS: This paper reviews the rationale and design of TREAD and illustrates how we address several key issues in contemporary patient-oriented research on MDD: 1) the use of augmentation strategies in the treatment of depressive disorders in general, 2) the use of non-pharmacological strategies in the treatment of depressive disorders, 3) the considerations of designing a well-controlled trial using two active treatment groups, and 4) the implementation of an adherence program for the use of exercise as a treatment strategy. CONCLUSIONS: The TREAD study is uniquely designed to overcome sources of potential bias and threats to internal and external validity that have limited prior research on the mental health effects of exercise. The study is facilitated by the development of a multidisciplinary research team that includes experts in both depression treatment and exercise physiology, as well as other related fields.

Adolescent↗

PubMed2006

The importance of waist circumference in the definition of metabolic syndrome: prospective analyses of mortality in men.

OBJECTIVE: The purpose of this study was to compare the predictive ability of the National Cholesterol Education Panel (NCEP), revised NCEP (NCEP-R), and International Diabetes Federation (IDF) metabolic syndrome criteria for mortality risk, and to examine the effects of waist circumference on mortality within the context of these criteria. RESEARCH DESIGN AND METHODS: The sample included 20,789 white, non-Hispanic men 20-83 years of age from the Aerobics Center Longitudinal Study. The main outcome measures were all-cause and cardiovascular disease (CVD) mortality over 11.4 years of follow-up. RESULTS: The proportions of men with the metabolic syndrome were 19.7, 27, and 30% at baseline, respectively, according to NCEP, NCEP-R, and IDF criteria. A total of 632 deaths (213 CVD) occurred. The relative risks (RRs) and 95% CIs of all-cause mortality were 1.36 (1.14-1.62), 1.31 (1.11-1.54), and 1.26 (1.07-1.49) for the NCEP, NCEP-R, and IDF definitions, respectively. The corresponding RRs for CVD mortality were 1.79 (1.35-2.37), 1.67 (1.27-2.19), and 1.67 (1.27-2.20). Additionally, there was a significant trend for a higher risk of CVD mortality across waist circumference categories (<94, 94-102, and >102 cm) among men with at least two additional metabolic syndrome risk factors (P = 0.01). CONCLUSIONS: The prediction of mortality with IDF and NCEP metabolic syndrome criteria was comparable in men. Waist circumference is a valuable component of metabolic syndrome; however, the IDF requirement of an elevated waist circumference warrants caution given that a large proportion of men with normal waist circumference have multiple risk factors and an increased risk of mortality.

Adult↗

PubMed2006

Does measurement site for visceral and abdominal subcutaneous adipose tissue alter associations with the metabolic syndrome?

OBJECTIVE: To determine whether the associations between visceral adipose tissue (VAT), abdominal subcutaneous adipose tissue (ASAT), and the metabolic syndrome are altered depending on measurement site for VAT and ASAT and the definition used to identify the metabolic syndrome. RESEARCH DESIGN AND METHODS: Total VAT and ASAT volume was derived using approximately 37 contiguous computed tomography (CT) images from T10-T11 to L5-S1 in 85 men. CT images obtained at eight intervertebral locations (e.g., L4-L5, L3-L4, etc.) were used to determine the associations between partial volumes (single images) and metabolic syndrome. Metabolic syndrome was defined using the National Cholesterol Education Program (NCEP) and International Diabetes Federation (IDF) criteria. Logistic regression was used to calculate the odds ratio (OR) per SD increase in adipose tissue. RESULTS: For total and all partial volumes, VAT was more strongly associated with metabolic syndrome than ASAT independent of metabolic syndrome criteria. The OR (per SD) for NCEP metabolic syndrome was higher for total VAT volume (OR = 7.26) and for the partial volumes at T12-L1 (7.46) and L1-L2 (8.77) than those at the L4-L5 level (3.94). The OR for metabolic syndrome ( approximately 2.6) was not substantially different among the ASAT measures. A similar pattern of association was observed using the IDF metabolic syndrome criteria. CONCLUSIONS: The measurement site for VAT, but not for ASAT, has a substantial influence on the magnitude of the association with both metabolic syndrome definitions. However, because VAT remained significantly associated with metabolic syndrome regardless of measurement site, the clinical interpretation was unaltered by measurement protocol or metabolic syndrome definition.

Abdominal Fat↗

PubMed2005

Protocol for measurement of liver fat by computed tomography.

To develop a protocol for measurement of liver fat using computed tomography (CT), we conducted a preliminary study with 118 men and 76 women to determine a readily identifiable vertebral landmark at which the CT image displayed both liver and spleen. Analysis of five landmarks revealed that the CT image obtained at the T12-L1 level simultaneously displayed the liver and spleen in 90% of the men and women. The T12-L1 protocol was cross-validated on a sample of 130 men and 113 women. In this sample, we also assessed the regional characteristics of liver and spleen tissue attenuation at the T12-L1 level by subdividing each image into quartiles from anterior to posterior, each of which were further divided into medial and lateral regions. A similar analysis was performed on images located 12 mm above and below T12-L1. The T12-L1 image displayed both liver and spleen in 92% (403 of 437) of the combined study sample. There was a significant (P<0.005) stepwise increase in attenuation values [Hounsfield units (HU)] from the inferior to superior image. Although some significant (P<0.05) differences were observed between the eight regions by comparison to the whole liver or spleen, the average magnitude of the difference was <2.0 HU for liver and <3.5 HU for spleen. Acquisition of a single CT image at the T12-L1 level is a practical and reliable method for routine measurement of liver fat in research and clinical settings.

Adult↗

PubMed2005

Cardiorespiratory fitness and body mass index as predictors of cardiovascular disease mortality among men with diabetes.

BACKGROUND: Questions remain as to whether higher levels of cardiorespiratory fitness, a measure of regular physical activity, are associated with lower risk of cardiovascular disease (CVD) mortality in overweight and obese individuals with diabetes. Our objective was to quantify the independent and joint relations of cardiorespiratory fitness (hereafter, fitness) and body mass index (BMI; calculated as weight in kilograms divided by the square of height in meters) with CVD mortality in men with diabetes. METHODS: This study was conducted using prospective observational data from the Aerobics Center Longitudinal Study. Study participants comprised 2316 men with no history of stroke or myocardial infarction and who were diagnosed as having diabetes (mean [SD] age, 50 [10] years); had a medical examination, including a maximal exercise test during 1970 to 1997 with mortality surveillance to December 31, 1998; and had a BMI of 18.5 or greater and less than 35.0. The main outcome measure was CVD mortality across levels of fitness with stratification by BMI. RESULTS: We identified 179 CVD deaths during a mean (SD) follow-up of 15.9 (7.9) years and 36,710 man-years of exposure. In a model containing age, examination year, fasting glucose level, systolic blood pressure, parental history of premature CVD, total cholesterol level, cigarette smoking, abnormal resting, and exercise electrocardiograms, a significantly higher adjusted risk of mortality was observed in men with a low fitness level who were normal weight (hazard ratio, 2.7 [95% confidence interval, 1.3-5.7]), overweight (hazard ratio, 2.7 [95% confidence interval, 1.4-5.1]), and class 1 obese (hazard ratio, 2.8 [95% confidence interval, 1.4-5.1]) compared with normal weight men with a high fitness level. CONCLUSION: In this cohort of men with diabetes, low fitness level was associated with increased risk of CVD mortality within normal weight, overweight, and class 1 obese weight categories.

Body Mass Index↗

PubMed2005

Revised Adult Treatment Panel III guidelines and cardiovascular disease mortality in men attending a preventive medical clinic.

BACKGROUND: National Cholesterol Education Program Adult Treatment Panel III guidelines recommend therapeutic lifestyle changes (TLC) and drug therapy to reduce cardiovascular disease (CVD) risk. These guidelines have been revised recently (ATP III-R); however, the risk of CVD mortality within each intervention window and the effects of cardiorespiratory fitness (CRF) and metabolic syndrome on CVD mortality within the framework of the guidelines are unknown. METHODS AND RESULTS: Risk factor and CRF data from 19,125 men (aged 20 to 79 years) who attended a preventive medical clinic between 1979 and 1995 were used. Mortality follow-up was completed until December 31, 1996. Participants were assigned to ATP III-R groups (LDL-C goal, TLC initiation, and drug consideration), and risk of CVD mortality was assessed by Cox proportional hazards regression. There were 179 CVD deaths over an average 10.2 years of follow-up. Compared with the LDL-C goal group, men in the TLC initiation and drug consideration groups had an elevated risk of CVD mortality (TLC initiation: HR=2.65, 95% CI 1.67 to 4.19; drug consideration: HR=6.44, 95% CI 4.49 to 9.25). Compared with LDL-C goal/fit, CVD mortality risk was higher in the LDL-C goal/unfit (4.8, 2.5 to 9.1), TLC initiation/fit (3.0, 1.7 to 5.3), TLC initiation/unfit (7.5, 3.7 to 15.2), drug consideration/fit (7.2, 4.6 to 11.4), and drug consideration/unfit (14.9, 9.1 to 24.4) groups. A similar gradient was observed for metabolic syndrome across intervention windows. CONCLUSIONS: Men eligible for TLC or drug consideration under ATP III-R were at elevated risk of CVD mortality compared with men who met the LDL-C goal. Furthermore, men who were physically fit or who did not have the metabolic syndrome had a lower risk of CVD mortality.

Adult↗

PubMed2005

Coronary artery calcium score and coronary heart disease events in a large cohort of asymptomatic men and women.

Coronary artery calcium (CAC), a measure of subclinical coronary heart disease (CHD), may be useful in identifying asymptomatic persons at risk of CHD events. The current study included 10,746 adults who were 22-96 years of age, were free of known CHD, and had their CAC quantified by electron-beam tomography at baseline as part of a preventive medical examination at the Cooper Clinic (Dallas, Texas) during 1995-2000. During a mean follow-up of 3.5 years, 81 hard events (CHD death, nonfatal myocardial infarction) and 287 total events (hard events plus coronary revascularization) occurred. Age-adjusted rates (per 1,000 person-years) of hard events were computed according to four CAC categories: no detectable CAC and incremental sex-specific thirds of detectable CAC; these rates were, respectively, 0.4, 1.5, 4.8, and 8.7 (trend p<0.0001) for men and 0.7, 2.3, 3.1, and 6.3 (trend p=0.02) for women. CAC levels also were positively associated with rates of total CHD events for women and men (trend p<0.0001 each). The association between CAC and CHD events remained significant after adjustment for CHD risk factors. CAC was associated with CHD events in persons with no baseline CHD risk factors and in younger (aged <40 years) and older (aged >65 years) study participants. These findings show that CAC is associated with an increased risk of CHD events in asymptomatic women and men.

Adult↗

PubMed2005

Cardiorespiratory fitness is inversely associated with the incidence of metabolic syndrome: a prospective study of men and women.

BACKGROUND: Few studies have reported the relationship between cardiorespiratory fitness and metabolic syndrome incidence, particularly in women. METHODS AND RESULTS: We prospectively studied 9007 men (mean+/-SD age, 44+/-9 years; body mass index, 25+/-3 kg/m2) and 1491 women (age, 44+/-9 years; body mass index, 22+/-2 kg/m2) who were free of metabolic syndrome and for whom measures of waist girth, resting blood pressure, fasting lipids, and glucose were taken during baseline and follow-up examinations. Baseline cardiorespiratory fitness was quantified as duration of a maximal treadmill test. Metabolic syndrome was defined with NCEP ATP-III criteria. During a mean follow-up of 5.7 years, 1346 men and 56 women developed metabolic syndrome. Age-adjusted incidence rates were significantly lower (linear trend, P<0.001) across incremental thirds of fitness in men and women. After further adjustment for potential confounders, multivariable hazard ratios for incident metabolic syndrome among men in the low, middle, and upper thirds of fitness, were 1.0 (referent), 0.74 (95% CI, 0.65 to 0.84), and 0.47 (95% CI, 0.40 to 0.54) (linear trend P<0.001); in women, they were 1.0 (referent), 0.80 (95% CI, 0.44 to 1.46), and 0.37 (95% CI, 0.18 to 0.80) (linear trend P=0.01), respectively. Similar patterns of significant inverse associations between fitness and metabolic syndrome incidence were seen when men were stratified on categories of body mass index, age, and number of baseline metabolic risk factors, but patterns were variable in women. CONCLUSIONS: Low cardiorespiratory fitness is a strong and independent predictor of incident metabolic syndrome in women and men. Clinicians should consider the potential benefits of greater cardiorespiratory fitness in the primary prevention of metabolic syndrome, particularly among patients who have already begun to cluster metabolic syndrome components.

Adult↗

PubMed2005

The Cooper Clinic Mortality Risk Index: clinical score sheet for men.

BACKGROUND: Clinical measures that are used to identify risk for specific diseases may also help physicians predict overall mortality risk in their patients. This study derived and validated a clinical scoring system that can be used to predict all-cause mortality risk in men using age, resting heart rate, blood pressure, total cholesterol, HDL-cholesterol, triglycerides, diabetes, obesity, smoking status, and cardiorespiratory fitness categories. METHODS: This was a cohort-based prospective study of 21,766 men with no prior history of coronary heart disease, stroke, or cancer. Participants were aged 20 to 69 years at the time of their clinical examination between 1979 and 1998. The cohort was subdivided into a derivation group and a validation group. All participants underwent a clinical examination including an exercise test to determine cardiorespiratory fitness. Blood pressure, total and HDL-cholesterol, triglycerides, diabetes, and adiposity status were categorized according to clinical guidelines. Within the derivation group, a point scoring system was developed to predict all-cause mortality based on a proportional hazards regression. The point scoring system was then tested within the validation group. Data were analyzed in January 2005. RESULTS: For the clinical mortality scoring system, the most points were assigned for greater age (e.g., 10 points for 65- to 69-year-olds), followed by diabetes (4 points), current smoking (4 points), severe obesity (3 points), low fitness (2 points), high resting heart rate (2 points), hypertension (2 points), and former smoking (1 point). A graded relationship was observed between total risk factor points and mortality risk within the derivation group, and the point scoring system accurately predicted mortality risk in the validation group. The discriminatory accuracy of the point scoring system was within acceptable limits in both the derivation group and validation group. CONCLUSIONS: A score sheet for predicting all-cause mortality risk in men, The Cooper Clinic Mortality Risk Index, was derived and validated. This score sheet may help healthcare practitioners identify high-risk patients who might benefit from lifestyle modification, pharmacologic therapy, or other interventions.

Adult↗

PubMed2005

Assessing cardiorespiratory fitness without performing exercise testing.

BACKGROUND: Low cardiorespiratory fitness (CRF) is associated with increased risk of chronic diseases and mortality; however, CRF assessment is usually not performed in many healthcare settings. The purpose of this study is to extend previous work on a non-exercise test model to predict CRF from health indicators that are easily obtained. METHODS: Participants were men and women aged 20 to 70 years whose CRF level was quantified with a maximal or submaximal exercise test as part of the National Aeronautics and Space Administration/Johnson Space Center (NASA, n = 1863), Aerobics Center Longitudinal Study (ACLS, n = 46,190), or Allied Dunbar National Fitness Survey (ADNFS, n = 1706). Other variables included gender, age, body mass index, resting heart rate, and self-reported physical activity levels. RESULTS: All variables used in the multiple linear regression models were independently related to the CRF in each of the study cohorts. The multiple correlation coefficients obtained within NASA, ACLS, and ADNFS participants, respectively, were 0.81, 0.77, and 0.76. The standard error of estimate (SEE) was 1.45, 1.50, and 1.97 metabolic equivalents (METs) (1 MET = 3.5 ml O(2) uptake.kilograms of body mass(-1).minutes(-1)), respectively, for the NASA, ACLS, and ADNFS regression models. All regression models demonstrated a high level of cross-validity (0.72 < R < 0.80). The highest cross-validation coefficients were seen when the NASA regression model was applied to the ACLS and ADNFS cohorts (R = 0.76 and R = 0.75, respectively). CONCLUSIONS: This study suggests that CRF may be accurately estimated in adults from a non-exercise test model including gender, age, body mass index, resting heart rate, and self-reported physical activity.

Adult↗

PubMed2005

Cholesterol-lowering effects of bovine serum immunoglobulin in participants with mild hypercholesterolemia.

BACKGROUND: The consumption of milk products has been shown to lower cholesterol. The mechanism of action surrounding this observation has been attributed to the protein fraction of milk and serum. OBJECTIVE: We examined the effect of an oral serum bovine immunoglobulin protein fraction (bIg) derived from US Department of Agriculture-approved beef (aged <30 mo) on lipid indexes in humans. DESIGN: Participants included men and women (aged 25-70 y) with hypercholesterolemia (5.44-6.99 mmol/L) who were not receiving cholesterol-lowering medication. Treatment consisted of the randomized, double-blind, parallel-group, placebo-controlled administration of 5 g bIg for 6 wk in 52 participants (n = 26 each in treatment and control groups). RESULTS: Mean (+/-SD) total cholesterol (TC) at baseline was 6.33 +/- 0.1 mmol/L for bIg and 6.16 +/- 0.1 mmol/L for placebo. A repeated-measures multivariate analysis of covariance covaried for change in total energy and alcohol intake and Tukey's post hoc examination of our data showed that the bIg-treated group had a significant reduction in TC at 3 wk (5.98 +/- 0.5 mmol/L; P < 0.05) and 6 wk (5.97 +/- 0.7 mmol/L; P < 0.05). The concentration at 6 wk was significantly different from that in the placebo group (P < 0.05). This reduction was largely due to a decrease in LDL cholesterol in the bIg-treated group from baseline (4.12 +/- 0.6 mmol/L) at 3 wk (3.92 +/- 0.7 mmol/L, P < 0.05) and at 6 wk (3.84 +/- 0.6 mmol/L, P < 0.05); the 6-wk concentration differed significantly between the treatment and placebo groups (P < 0.05). We observed no significant changes in the placebo group or in any other lipid indexes or markers associated with hepatorenal or cardiovascular function. CONCLUSION: Consumption of bIg appears to positively modulate the primary lipid indexes associated with cardiovascular disease.

Adult↗

PubMed2005

Physical activity and diabetes prevention.

Diabetes has reached epidemic proportions worldwide and is associated with a large economic burden, increased risk of cardiovascular disease, and premature mortality. Hyperglycemia is the hallmark clinical manifestation of diabetes and evolves through a multifactorial etiology of genetic, environmental, and behavioral enablers. Approximately 90% of diabetes cases are the non-insulin-dependent phenotype, which is characterized by a progressive deterioration in insulin-mediated glucose disposal, particularly by peripheral tissues. Our hypothesis is that the most proximal behavioral cause of insulin resistance is physical inactivity. Indeed, several streams of scientific research have demonstrated a role for physical activity in the etiology and prevention of diabetes and its related morbidity. In this review we will discuss some of the key observational and experimental studies that have examined associations among physical activity, cardiorespiratory fitness, and non-insulin-dependent diabetes.

Clinical Trials as Topic↗

PubMed2005

Association of muscular strength with incidence of metabolic syndrome in men.

PURPOSE: To examine the association between muscular strength and incidence of metabolic syndrome. METHODS: Participants were 3233 men (20-80 yr) initially free of metabolic syndrome who had two or more clinical examinations between 1980 and 2003, including baseline muscular strength and cardiorespiratory fitness assessment. Metabolic syndrome was defined according to NCEP-ATP III criteria. Muscular strength was quantified by combining body weight-adjusted one-repetition maximal measures for leg and bench presses. Cardiorespiratory fitness was assessed by maximal treadmill test. RESULTS: A total of 480 men developed metabolic syndrome during a mean follow-up period of 6.7 +/- 5.2 yr. In a Cox regression analysis adjusted for age, the hazard ratios (95% confidence intervals) of metabolic syndrome associated with the incremental categories of muscular strength were 1.00 (referent), 0.88 (0.69-1.12), 0.77 (0.60-0.98), and 0.54 (0.42-0.71), respectively (linear trend P < 0.0001). The inverse trend persisted after adjustment for smoking, alcohol intake, number of baseline metabolic syndrome risk factors, family history of diabetes, hypertension, and premature coronary disease (P = 0.004), but was attenuated (P = 0.06) when further adjusted for cardiorespiratory fitness. Compared with the lowest strength category, the highest strength category was associated with 44 and 39% lower risk (P < 0.05 each) of incident metabolic syndrome among normal weight body mass index (BMI < 25) and overweight or obese (BMI > or = 25) men, respectively. An inverse association of incident rates was also seen within stratum of age (20-39 yr, P < 0.001; 40-49 yr, P < 0.01; and 50+ yr, P < 0.05). CONCLUSIONS: Muscular strength was inversely associated with metabolic syndrome incidence, independent of age and body size. Potential benefits of greater muscular strength presumably through resistance exercise training should be considered in primary prevention of metabolic syndrome.

Age Factors↗

PubMed2005

Pedometer indices for weekly physical activity recommendations in postmenopausal women.

PURPOSE: The aim of this study was to quantify pedometer-determined steps per day associated with 50, 100, and 150% of the current public health recommendation for weekly physical activity in sedentary postmenopausal women. METHODS: A sample of 111 women from the DREW (Dose Response to Exercise in Women) study provided data. We randomly assigned women into one of three exercise groups expending 4, 8, or 12 kcal(-1).kg(-1).wk(-1) (KKW). Participants exercised alternately on a treadmill and recumbent cycle ergometer for a 6-month training period. Only treadmill sessions done with zero grade, at slow to moderate speeds (48-97 m.min(-1)) were used in this analysis. We controlled intensity at a HR equivalent to 50% of VO(2peak). Participants wore pedometers at baseline and throughout the study to assess their free-living physical activity (steps.d(-1)) RESULTS: Baseline averages were <5400 steps.d(-1) for the 4-, 8-, and 12-KKW groups. During 6 months of exercise training, free-living step counts remained <5400 steps.d(-1) and did not significantly differ from baseline for each group. Average speeds and distances per exercise session were 2.7 +/- 0.4 mph, 1.2 +/- 0.2 miles (4 KKW), 2.6 +/- 0.4 mph, 2.2 +/- 0.4 miles (8 KKW), and 2.8 +/- 0.3 mph, 2.7 +/- 0.4 miles (12 KKW). This yielded 2771 (4 KKW), 5457 (8 KKW), and 6534 (12 KKW) steps per exercise session 3-4 d.wk(-1). CONCLUSIONS: Initially sedentary postmenopausal women can meet 50% (4 KKW), 100% (8 KKW), and 150% (12 KKW) of the current public health recommendation of weekly physical activity through planned moderate-intensity walking, accumulating an average of about 2800 (50%), 5500 (100%), and 6500 steps.d(-1) (150%) 3-4 d.wk(-1).

Energy Metabolism↗