The association between physical activity and both incident coronary artery calcification and ankle brachial index progression: the multi-ethnic study of atherosclerosis.

OBJECTIVE: Both coronary artery calcification (CAC) and the ankle brachial index (ABI) are measures of subclinical atherosclerotic disease. The influence of physical activity on the longitudinal change in these measures remains unclear. To assess this relation we examined the association between these measures and self-reported physical activity in the Multi-Ethnic Study of Atherosclerosis (MESA). METHODS: At baseline, the MESA participants were free of clinically evident cardiovascular disease. We included all participants with an ABI between 0.90 and 1.40 (n = 5656). Predictor variables were based on self-reported measures with physical activity being assessed using the Typical Week Physical Activity Survey from which metabolic equivalent-minutes/week of activity were calculated. We focused on physical activity intensity, intentional exercise, sedentary behavior, and conditioning. Incident peripheral artery disease (PAD) was defined as the progression of ABI to values below 0.90 (given the baseline range of 0.90-1.40). Incident CAC was defined as a CAC score >0 Agatston units upon follow up with a baseline score of 0 Agatston units. RESULTS: Mean age of participants was 61 years, 53% were female, and mean body mass index was 28 kg/m(2). After adjusting for traditional cardiovascular risk factors and socioeconomic factors, intentional exercise was protective for incident peripheral artery disease (Relative Risk (RR) = 0.85, 95% Confidence Interval (CI): 0.74-0.98). After adjusting for traditional cardiovascular risk factors and socioeconomic factors, there was a significant association between vigorous PA and incident CAC (RR = 0.97, 95% CI: 0.94-1.00). There was also a significant association between sedentary behavior and increased amount of CAC among participants with CAC at baseline (Δlog (Agatston Units + 25) = 0.027, 95% CI 0.002, 0.052). CONCLUSIONS: These data suggest that there is an association between physical activity/sedentary behavior and the progression of two different measures of subclinical atherosclerotic disease.

Null association between abdominal muscle and calcified atherosclerosis in community-living persons without clinical cardiovascular disease: the multi-ethnic study of atherosclerosis.

OBJECTIVE: Lean muscle loss has been hypothesized to explain J-shaped relationships of body mass index (BMI) with cardiovascular disease (CVD), yet associations of muscle mass with CVD are largely unknown. We hypothesized that low abdominal lean muscle area would be associated with greater calcified atherosclerosis, independent of other CVD risk factors. MATERIALS/METHODS: We investigated 1020 participants from the Multi-Ethnic Study of Atherosclerosis who were free of clinical CVD. Computed tomography (CT) scans at the 4th and 5th lumbar disk space were used to estimate abdominal lean muscle area. Chest and abdominal CT scans were used to assess coronary artery calcification(CAC), thoracic aortic calcification (TAC), and abdominal aortic calcification (AAC). RESULTS: The mean age was 64±10 years, 48% were female, and mean BMI was 28±5 kg/m2. In models adjusted for demographics, physical activity, caloric intake, and traditional CVD risk factors, there was no inverse association of abdominal muscle mass with CAC (prevalence ratio [PR] 1.02 [95% CI 0.95,1.10]), TAC (PR 1.13 [95% CI 0.92, 1.39]) or AAC (PR 0.99 [95% CI 0.94, 1.04]) prevalence. Similarly, there was no significant inverse relationship between abdominal lean muscle area and CAC, TAC, and AAC severity. CONCLUSION: In community-living individuals without clinical CVD, greater abdominal lean muscle area is not associated with less calcified atherosclerosis.

Sedentary behavior and adiposity-associated inflammation: the Multi-Ethnic Study of Atherosclerosis.

BACKGROUND: Sedentary behavior is associated with adiposity and cardiometabolic risk. PURPOSE: To determine the associations between sedentary behavior and measures of adiposity-associated inflammation. METHODS: Between 2002 and 2005, a total of 1543 Multi-Ethnic Study of Atherosclerosis participants completed detailed health history questionnaires, underwent physical measurements, and had blood assayed for adiponectin, leptin, tumor necrosis factor-alpha (TNF-α) and resistin. Analyses included linear regression completed in 2010. The mean age was 64.3 years and nearly 50% were female. Forty-one percent were non-Hispanic white, 24% Hispanic-American, 20% African-American, and 14% Chinese-American. RESULTS: In linear regression analyses and with adjustment for age, gender, ethnicity, education, BMI, smoking, alcohol consumption, hypertension, diabetes mellitus, dyslipidemia, hormone therapy and waist circumference, sedentary behavior was associated with higher natural log ("ln") of leptin and ln TNF-α but a lower ln adiponectin-to-leptin ratio (ß=0.07, ß=0.03 and -0.07, p<0.05 for all). Compared to the first tertile, and after the same adjustment, the second and third tertiles of sedentary behavior were associated with higher levels of ln leptin (ß=0.11 and ß=0.12, respectively; p<0.05 for both) but lower levels of the adiponectin-to-leptin ratio (ß=-0.09 and -0.11, respectively; p<0.05 for both). CONCLUSIONS: Sedentary behavior is associated with unfavorable levels of adiposity-associated inflammation.

The association of bone density and calcified atherosclerosis is stronger in women without dyslipidemia: the multi-ethnic study of atherosclerosis.

We tested whether the association between bone mineral density (BMD) and coronary artery calcification (CAC) varies according to dyslipidemia in community-living individuals. Between 2002 and 2005, 305 women and 631 men (mean age of 64 years), who were not taking lipid-lowering medications or estrogen were assessed for spine BMD, CAC, and total (TC), HDL- and LDL-cholesterol and triglycerides. Participants were a random sample from the Multi-Ethnic Study of Atherosclerosis (MESA) without clinical cardiovascular disease. Spine BMD at the L3 vertebrate was performed by computer tomography (CT). CAC prevalence was measured by CT. The total cholesterol to HDL ratio (TC:HDL) ≥ 5.0 was used as the primary marker of hyperlipidemia. The association of BMD with CAC differed in women with TC:HDL < 5.0 versus higher (p-interaction = 0.01). In age- and race-adjusted models, among women with TC:HDL < 5.0, each SD (43.4 mg/cc) greater BMD was associated with a 25% lower prevalence of CAC (prevalence ratio [PR] 0.75, 95% confidence interval [CI] 0.63-0.89), whereas among women with higher TC:HDL, higher BMD was not significantly associated with CAC (PR 1.22, 95% CI 0.82-1.82). Results were similar using other definitions of hyperlipidemia. In contrast, no consistent association was observed between BMD and CAC in men, irrespective of the TC:HDL ratio (p interaction 0.54). The inverse association of BMD with CAC is stronger in women without dyslipidemia. These data argue against the hypothesis that dyslipidemia is the key factor responsible for the inverse association of BMD with atherosclerosis.

The epidemiology of subclavian artery calcification.

OBJECTIVES: The purpose of the present study was to determine the prevalence and risk factor associations for subclavian artery calcification. BACKGROUND: Arterial calcification is a marker of atherosclerosis, and its presence portends an adverse prognostic risk. The prevalence and associated risk factors for aortic arch, carotid, renal, and coronary calcification have been well described. Fewer data are available for subclavian artery calcification. METHODS: Electron-beam computed tomography was used to evaluate the extent of vascular calcification in multiple arterial beds in 1387 consecutive individuals who presented for preventive medicine services at a university-affiliated disease prevention center. Laboratory values for blood pressure, lipids, anthropomorphic data, and self-reported medical history were obtained. RESULTS: Subclavian artery calcification was present in 439 of 1387 individuals (31.7%). Those with subclavian artery calcification were significantly older, had a smaller body mass index, and were more likely to also have calcification of nonsubclavian vascular beds. When adjusted for cardiovascular disease risk factors, the presence of subclavian artery calcification was significantly associated with age (prevalence ratio [PR], 1.04; P < .001), hypertension (PR, 1.20; P = .01), history of smoking (PR, 1.21; P = .01), and calcification in nonsubclavian vascular beds (PR, 1.58; P = .01). Subclavian artery calcification was also associated with an increased pulse pressure (ß-coefficient = 2.2, P = .008). CONCLUSIONS: Subclavian artery calcification is relatively common and is significantly associated with age, smoking, hypertension, and nonsubclavian vascular calcification. There may be a relationship between vascular stiffness, as manifested by a widened pulse pressure, and the presence of subclavian artery calcification.

The association between abdominal body composition and vascular calcification.

Subclinical cardiovascular disease (CVD) may be associated with both adipose and skeletal muscle tissues in the abdomen. Accordingly, we examined whether subcutaneous, intermuscular, and visceral adipose tissue, as well as abdominal lean muscle, were associated with the presence and extent of vascular calcification in multiple vascular beds. Three hundred and ninety four patients (58.1% men) underwent electron beam computed tomography (EBCT) scans as part of routine health maintenance screening. The coronary and carotid calcium scores were analyzed at the time of the scan, whereas the other calcium scores, as well as the body composition analyses, were analyzed retrospectively. Mean age was 55.2 ± 11.1 years and BMI was 26.9 ± 4.2. The prevalence of any calcification in the carotids, coronaries, thoracic aorta, abdominal aorta, and iliacs was 30.1, 60.1, 39.8, 55.7, and 56.8%, respectively. Compared to those with calcification in different vascular beds, those without vascular calcification generally had significantly more lean muscle and less adipose tissue. In separate multivariable logistic models, a 1 s.d. increment in the ratio of abdominal and visceral fat to total area of each corresponding compartments was significantly associated with an increased odds for the presence of thoracic aortic calcium (odds ratio (OR) = 1.6, 1.5, respectively; P = 0.01 for both). Conversely, increases in abdominal lean muscle were associated with significantly decreased odds of thoracic aortic calcification (OR = 0.34; P ≤ 0.01). A similar pattern of associations existed among the other vascular beds. Also, the association between lean muscle and vascular calcification was independent of visceral adipose tissue. In conclusion, adipose tissue was positively and lean body mass inversely associated with prevalent aortic calcification.

The Stayhealthy bioelectrical impedance analyzer predicts body fat in children and adults.

Bioelectrical impedance analysis (BIA) is a time-efficient and cost-effective method for estimating body composition. We hypothesized that there would be no significant difference between the Stayhealthy BC1 BIA and the selected reference methods when determining body composition. Thus, the purpose of the present study was to determine the validity of estimating percent body fat (%BF) using the Stayhealthy BIA with its most recently updated algorithms compared to the reference methods of dual-energy x-ray absorptiometry for adults and hydrostatic weighing for children. We measured %BF in 245 adults aged 18 to 80 years and 115 children aged 10 to 17 years. Body fat by BIA was determined using a single 50 kHz frequency handheld impedance device and proprietary software. Agreement between BIA and reference methods was assessed by Bland and Altman plots. Bland and Altman analysis for men, women, and children revealed good agreement between the reference methods and BIA. There was no significant difference by t tests between mean %BF by BIA for men, women, or children when compared to the respective reference method. Significant correlation values between BIA, and reference methods for all men, women, and children were 0.85, 0.88, and 0.79, respectively. Reliability (test-retest) was assessed by intraclass correlation coefficient and coefficient of variation. Intraclass correlation coefficient values were greater than 0.99 (P < .001) for men, women, and children with coefficient of variation values 3.3%, 1.8%, and 1.7%, respectively. The Stayhealthy BIA device demonstrated good agreement between reference methods using Bland and Altman analyses.

Blood pressure and vascular calcification.

The aim of this study was to determine the associations between the presence and extent of calcified atherosclerosis in multiple vascular beds and systolic blood pressure, diastolic blood pressure, pulse pressure, mean arterial pressure, isolated systolic hypertension, and hypertension. A total of 9510 patients (42.5% women) underwent electron beam computed tomography scanning as part of a routine health maintenance screening. At the same visit, blood pressure was measured with the participant in the seated position using a mercury sphygmomanometer. Mean age was 58+/-11.4 years, and body mass index was 27.1+/-4.5. The prevalences of any calcification in the carotids, coronaries, subclavians, thoracic aorta, abdominal aorta, and iliacs were 31.9%, 57.2%, 31.7%, 37.0%, 54.3%, and 48.8%, respectively. In separate multivariable logistic models containing traditional cardiovascular disease risk factors, pulse pressure and systolic blood pressure were significantly associated with the presence of calcification in all of the vascular beds except the iliacs and subclavians, respectively, with pulse pressure having stronger magnitudes of the associations for most of the vascular beds. Age-stratified analyses indicated that these associations were stronger in those >60 years of age compared with subjects <60 years of age, and sex-stratified analyses demonstrated that men had a greater association compared with women. Also, the magnitudes of the associations for isolated systolic hypertension were, in general, larger than those for hypertension. Pulse pressure and isolated systolic hypertension are robust and important correlates for calcified atherosclerosis in different vascular beds. Isolated systolic hypertension may be clinically relevant in diagnosing or preventing calcified atherosclerosis.

Exercise does not influence myostatin and follistatin messenger RNA expression in young women.

We evaluated changes in myostatin, follistatin, and MyoD messenger RNA (mRNA) gene expression using eccentric exercise (EE) and concentric exercise (CE) as probes to better understand the mechanisms of muscle hypertrophy in young women. Twelve women performed single-leg maximal eccentric (n = 6, 25 +/- 1 years, 59 +/- 7 kg) or concentric (n = 6, 24 +/- 1 years, 65 +/- 7 kg) isokinetic knee extension exercise for 7 sessions. Muscle biopsies were taken from the vastus lateralis at baseline, 8 hours after the first exercise session, and 8 hours after the seventh exercise session. In the EE group, there were no changes in myostatin and follistatin (p > or = 0.17); however, MyoD expression increased after 1 exercise bout (p = 0.02). In the CE group, there were no changes in myostatin, follistatin, or MyoD mRNA gene expression (p > or = 0.07). Differences between the EE and CE groups were not significant (p > or = 0.05). These data suggest that a single bout or multiple bouts of maximal EE or CE may not significantly alter myostatin or follistatin mRNA gene expression in young women. However, MyoD mRNA expression seems to increase only after EE.

Validation of the CardioCoachCO2 for submaximal and maximal metabolic exercise testing.

This study examined the validity of the CardioCoachCO2 metabolic system to measure oxygen capacity by comparison to a previously validated device. Fourteen subjects (8 men and 6 women; 25.9 +/- 6.6 years of age) completed 2 maximal graded exercise tests on a cycle ergometer. Subjects were randomly tested on the CardioCoachCO2 and Medical Graphics CardiO2/CP (MedGraphics) system on 2 separate visits. The exercise test included 3 submaximal 3-minute stages (50, 75, and 100 W for women; 50, 100, and 150 W for men) followed by incremental, 25 W, 1-minute stages until volitional fatigue (Vo2max). There was no significant difference between the CardioCoachCO2 and MedGraphics except at the 100 W stage (22.4 +/- 4.8 and 20.3 +/- 3.7 ml x kg(-1) x min(-1), p = 0.048, respectively). Spearman correlations demonstrated a strong correlation between the 2 devices at maximal Vo2 (R = 0.94). Bland-Altman plots demonstrated small limits of agreement, indicating that the 2 devices are similar in measuring oxygen consumption. This study indicates that the CardioCoachCO2 is a valid device for testing Vo2 at submaximal and maximal levels. Validation of this device supports the CardioCoachCO2 as a feasible and convenient method for testing participants and may be useful in the field or clinic.

The influence of eccentric exercise on mRNA expression of skeletal muscle regulators.

To evaluate change in myostatin, follistatin, MyoD and SGT mRNA gene expression using eccentric exercise to study mechanisms of skeletal muscle hypertrophy. Young (28+/-5 years) and older (68+/-6 years) men participated in a bout of maximal single-leg eccentric knee extension on an isokinetic dynamometer at 60 degrees /s: six sets, 12-16 maximal eccentric repetitions. Muscle biopsies of the vastus lateralis were obtained from the dominant leg before exercise and 24 h after exercise. Paired t tests were used to compare change (pre versus post-exercise) for normalized gene expression in all variables. Independent t tests were performed to test group differences (young vs. older). A probability level of P0.23 for all variables. Our data suggests that a single bout of maximal eccentric exercise does not alter myostatin, follistatin, MyoD or SGT mRNA gene expression in young or older subjects.

Reliability of maximal voluntary muscle strength and power testing in older men.

BACKGROUND: Maximal voluntary muscle strength (MVMS) and leg power are important measures of physical function in older adults. We hypothesized that performing these measures twice within 7-10 days would demonstrate a >5% increase due to learning and familiarization of the testing procedures. METHODS: Data were collected from three studies in older adult men (60-87 years) and were divided into two cohorts defined by study site and type of exercise equipment. MVMS was assessed in 116 participants using the one-repetition maximum method at two separate study visits for the chest press, latissimus pull-down, leg press, leg flexion, and leg extension exercises along with unilateral leg extension power. RESULTS: Test-retest scores were not different and did not exceed 0.8 +/- 9.0% in Cohort 1 or 2.3 +/- 9.8% in Cohort 2, except for leg extension, which improved by 6.6 +/- 14.4% (p <.009) and 3.4 +/- 6.8% (p <.016), respectively. Repeat tests were closely correlated with initial tests (all p <.001). Pearson correlation coefficients ranged from 0.74 for leg extension power to 0.96 for leg press. Coefficients of variation were <10% (4.2%-9.0%) for all exercises except for leg extension power, which was 15.5%. CONCLUSIONS: Our findings demonstrated that test-retest measures of MVMS and power in older adult men do not differ by more than 2.3% except for leg extension, and have relatively low coefficients of variation using data collected from three studies. Moreover, these findings were similar between two study sites using different equipment, which further supports the reliability of MVMS and power testing in older adult men.

Longitudinal change in coronary heart disease risk factors in older runners.

BACKGROUND: it is currently not clear how coronary heart disease (CHD) risk factors change over time in chronic exercisers. Therefore, the purpose of this study is to describe the longitudinal change in CHD risk factors in chronically endurance-trained men and women, and to determine the exercise and nutritional factors associated with those respective changes. METHODS AND RESULTS: ninety-one middle-aged runners (56 male, 35 female) were tested on two occasions approximately 10 years apart (aged 50.8 +/- 8.0 versus 60.0 +/- 7.9 years at respective visits). Body composition, VO2max, blood pressure (BP) and blood chemistries were measured, and the subjects' self-reported training and nutritional history. Data were analysed by factorial analysis of variance (ANOVA) and multivariate step-wise regression. Among the entire sample, training volume decreased (61.1 +/- 28.2 versus 44.7 +/- 24.6 km/week, P<0.05) but nutritional variables did not change. Body fat (16.9 +/- 5.3% for men versus 21.1 +/- 5.3% for women, P<0.05), blood lipids, blood glucose and systolic and diastolic BP all changed negatively over the study duration. These changes occurred similarly in both genders and irrespective of menstrual and hormone replacement status among the women. Lastly, the changes in CHD risk factors were not predicted by change in exercise or nutritional patterns. CONCLUSIONS: despite the maintenance of significant volumes of exercise and the absence of changes in diet, most CHD risk factors demonstrated unfavourable changes over 10 years in chronic men and women runners. However, the absolute values for most CHD risk factors remained better than those reported for sedentary peers of comparable age.

Chronic exercise and skeletal muscle power in older men.

We sought to determine the effects of age and chronic exercise on muscle power in older males. We examined 32 older males 60-74 years of age and grouped as sedentary (CON, n = 11), chronic endurance trained (ET, n = 10), and chronic endurance trained + resistance training (ET + RT, n = 11). Exercise history was obtained by questionnaire. Absolute strength and power measures were obtained by the one-repetition maximum method. Relative strength and power were determined by dividing the absolute measure by the muscle mass involved in the exercise. Total and regional muscle mass was measured by DXA. Absolute and relative leg power were not significantly different among the 3 groups. In contrast, absolute leg press strength was greater in ET + RT compared with CON, and relative leg press strength was greater in ET and ET + RT compared with CON. Chronic running combined with resistance training may therefore enhance absolute and relative muscle strength in older adults, but does not influence muscle power. Endurance exercise may inhibit the ability of resistance exercise to positively influence skeletal muscle power.

Cardiopulmonary responses to eccentric and concentric resistance exercise in older adults.

BACKGROUND: In older ambulatory persons, exercise strategies that are expected to generate beneficial muscle adaptations with low cardiopulmonary demands are needed. OBJECTIVE: We hypothesised that eccentric resistance exercise would be less demanding on the cardiovascular and pulmonary systems than bouts of concentric resistance exercise. DESIGN: The effects of eccentric and concentric resistance exercise were compared during leg squats at a submaximal intensity known to increase muscle mass. SUBJECTS: 19 Older persons (15 women/four men, age 65 +/- 4 years) and 19 young reference controls (10 women/nine men; age 25 +/- 2 years) were enrolled. METHODS: Participants completed eccentric-only and concentric-only exercise bouts 5-7 days apart. RESULTS: Cardiovascular and pulmonary measures were collected from subjects during bouts consisting of three sequential sets of 10 repetitions at 65% of their voluntary concentric 1-repetition maximum force (68+/-16 kg for older participants and 94 +/- 36 kg for young participants). Peak heart rate (119 +/- 10 versus 155 +/- 16 b.p.m.), systolic blood pressure (129 +/- 18 versus 167 +/- 14 mmHg), cardiac index (7.8 +/- 2.0 versus 9.2 +/- 1.5 l/min/m2) and expired ventilation (20.5 +/- 5.7 versus 29.8 +/- 9.1 l/min) were significantly lower during eccentric than during concentric bouts in the older subjects, respectively (P < 0.001 for all comparisons). Similarly, peak heart rate, systolic blood pressure, cardiac index and expired ventilation were significantly lower during eccentric bouts in the young control subjects. CONCLUSIONS: Eccentric resistance exercise produced less cardiopulmonary demands and may be better suited for older persons with low exercise tolerance and at risk of adverse cardiopulmonary events.