Importance of aerobic fitness in cardiovascular risks in sedentary overweight and obese African-American women.

BACKGROUND: Whether the level of aerobic fitness significantly impacts cardiovascular disease (CVD) risks in healthy, nondiabetic, overweight or obese African-American women remains uncertain. OBJECTIVE: To examine the clinical and metabolic risk factors of CVD in nondiabetic, sedentary overweight or obese African-American women with varying degrees of aerobic fitness. METHODS: Forty-eight African-American women, with mean age of 43 +/- 4.2 years and body mass index of 32.3 +/- 3.6 kg/m2, participated in the study. Fasting and 2-hr postprandial serum glucose, insulin, and C-peptide levels were obtained during oral glucose tolerance test. Insulin sensitivity was calculated by Homeostasis Model Assessment (HOMA-IR). Aerobic fitness was categorized empirically as very low aerobic fitness (VLAF; n = 17, VO2max < 21 ml/kg/min), low aerobic fitness (LAF; n = 12, between 21 and 24.4 ml/kg/min), and moderate aerobic fitness (MAF; n = 19, >24.4 ml/kg/min). RESULTS: Significant differences were found in serum glucose, insulin, and C-peptide levels, and HOMA-IR in the VLAF vs. LAF and MAF groups. Mean HOMA-IR was statistically greater in the VLAF and LAF when compared to MAF. Mean fasting serum cholesterol, triglycerides, and low-density lipoprotein cholesterol levels were higher in the VLAF group compared to the MAF group, whereas high-density lipoprotein cholesterol was lower in the VLAF group. Despite differences in the obesity indices and insulin resistance in the three groups, the atherogenic lipids and lipoproteins were within normal limits, irrespective of degree of VO2max. DISCUSSION: Modest aerobic fitness has significant impact on insulin sensitivity and atherogenic lipids and lipoprotein parameters and the overall risks for CVD in sedentary overweight or obese African-American women. Whether modest physical fitness translates into prevention of type 2 diabetes and CVD in African-American women remains to be determined.

Aerobic exercise improves cardiorespiratory fitness but does not reduce blood pressure in prehypertensive African American women.

OBJECTIVE: To determine the effectiveness of a 10-week aerobic exercise training intervention on blood pressure, cardiorespiratory fitness, and workload in African American women with prehypertension. DESIGN: After we obtained informed consent and medical clearance, each participant underwent baseline measurements, an aerobic exercise-training regimen, and postintervention assessments. SETTING: This investigation took place in Columbus, Ohio, on the campus of The Ohio State University. PARTICIPANTS: Twelve sedentary African American women with prehypertension volunteered to participate. INTERVENTIONS: Study participants trained three days per week for 30 minutes per session at an intensity of 70% maximal oxygen consumption (VO2 peak) for 10 weeks. MAIN OUTCOME MEASURES: Blood pressure, cardiorespiratory fitness, and workload achieved. RESULTS: Exercise training resulted in a significant improvement in cardiorespiratory fitness and workload capacity. However, no significant reductions in blood pressure were seen after the 10-week aerobic exercise period. CONCLUSIONS: Ten weeks of 30 minutes of aerobic exercise, three times a week at 70% VO2 peak, is a sufficient stimulus to improve cardiorespiratory fitness and workload achieved. However, this exercise regimen was not adequate in eliciting a simultaneous reduction in systolic, diastolic, or mean arterial blood pressure in this cohort of prehypertensive African American women. Additional studies are needed to determine specific exercise protocols that would be effective in lowering blood pressure in various populations. These exercise protocols may vary across ethnicity, sex, and disease status.

A comparison of military circumference equations to skinfold-based equations to estimate body composition.

UNLABELLED: Circumference-based military equations (CBEs) were compared with a skinfold-based equation (SBE) to estimate body fat. OBJECTIVE: We determined the correlation between CBEs and SBE, evaluated the efficacy of CBE methods, and examined the difference in methods to identify noncompliant personnel. Circumference and skinfold measurements were taken in sequential order for 1,191 male civil service employees (37.9 +/- 7.9 years). RESULTS: Percent body fat was estimated for SBE (18.4 +/- 6.1) and three different CBEs: Marine Corps (19.6 +/- 5.8), Navy/Air Force (20.4 +/- 5.8), and Army (20.6 +/- 5.2). A moderate correlation coefficient existed between SBE and CBEs (r = 0.76-0.79). A greater body fat percentage was estimated in noncompliant personnel with circumference methods. CONCLUSIONS: Data moderately correlate CBEs and SBE. However, CBEs predict higher estimates, resulting in a greater number of personnel classified as noncompliant.

Nonthermal ultrasound and exercise in skeletal muscle regeneration.

OBJECTIVE: To determine whether continuous nonthermal therapeutic ultrasound (US) and low-intensity exercise (Ex) influence skeletal muscle regeneration after a standardized contusion injury in an animal model. DESIGN: Randomized controlled trial with blinded comparisons in a 2 x 2 factorial (US by Ex) design. SETTING: Animal care facility and exercise physiology biochemistry laboratory. ANIMALS: Twenty male Wistar rats (age, 8 mo) received a reproducible bilateral contusion injury to the gastrocnemius muscles. Ten gastrocnemius muscles from 5 noninjured, nontreated rats provided baseline control data. INTERVENTIONS: US (continuous duty cycle, 3 MHz; intensity, 0.1 W/cm2 ; transducer, 1cm2 ; duration, 5 min/d; duty cycle, 100%) and exercise (20 min/d of low-intensity treadmill walking at 14 m/min). Gastrocnemius muscles from injured rats received exercise treatment alone (Ex + NoUS), exercise and US treatment (Ex + US), US treatment alone (NoEx + US), and no treatment (NoEx + NoUS). MAIN OUTCOME MEASURES: Ninety-six-hour postinjury muscle mass, contractile protein concentration, fiber cross-sectional area, number of nuclei per fiber, and myonuclear density. RESULTS: Myonuclei per fiber were statistically greater in injured than in noninjured gastrocnemius muscle (P < .05). There were no statistical differences (P > .01) among the 4 injured treatment groups for any of the outcome measures chosen as biomarkers of skeletal muscle regeneration. CONCLUSIONS: There is no evidence that the specific continuous US and Ex protocols investigated enhanced skeletal muscle regeneration after contusion injury.

Maximal lactate steady state declines during the aging process.

Increased participation of aged individuals in athletics warrants basic research focused on delineating age-related changes in performance variables. On the basis of potential age-related declines in aerobic enzyme activities and a shift in the expression of myosin heavy chain (MHC) isoforms, we hypothesized that maximal lactate steady-state (MLSS) exercise intensity would be altered as a function of age. Three age groups [young athletes (YA), 25.9 +/- 1.0 yr, middle-age athletes (MA), 43.2 +/- 1.0 yr, and older athletes (OA), 64.6 +/- 2.7 yr] of male, competitive cyclists and triathletes matched for training intensity and duration were studied. Subjects performed a maximal O2 consumption (V(o2 max)) test followed by a series of 30-min exercise trials to determine MLSS. A muscle biopsy of the vastus lateralis was procured on a separate visit. There were differences (P < 0.05) in V(o2 max) among all age groups (YA = 67.7 +/- 1.2 ml x kg-1x min-1, MA = 56.0 +/- 2.6 ml x kg-1x min-1, OA = 47.0 +/- 2.6 ml x kg-1 x min-1). When expressed as a percentage of V(o2 max), there was also an age-related decrease (P < 0.05) in the relative MLSS exercise intensity (YA = 80.8 +/- 0.9%, MA = 76.1 +/- 1.4%, OA = 69.9 +/- 1.5%). There were no significant age-related changes in citrate synthase activity or MHC isoform profile. The hypothesis is supported as there is an age-related decline in MLSS exercise intensity in athletes matched for training intensity and duration. Although type I MHC isoform, combined with age, is helpful in predicting (r = 0.76, P < 0.05) relative MLSS intensity, it does not explain the age-related decline in MLSS.

Changes in concentrations of neuroendocrine hormones and catecholamines in dogs with myocardial failure induced by rapid ventricular pacing.

OBJECTIVE: To describe neuroendocrine responses that develop in dogs subjected to prolonged periods of ventricular pacing. ANIMALS: 14 adult male hound-type dogs. PROCEDURE: Samples were obtained and neuroendocrine responses measured before (baseline) and after 3 periods of ventricular pacing. A pacemaker was used to induce heart rates of 180, 200, and 220 beats/min (BPM). Each heart rate was maintained for 3 weeks before increasing to the next rate. Atrial natriuretic peptide, antidiuretic hormone, aldosterone, norepinephrine, epinephrine, and dopamine concentrations and plasma renin activity were measured. Severity of left ventricular compromise was estimated. RESULTS: Shortening fraction decreased significantly with increasing heart rates (mean +/- SE, 35.5 +/- 1.4, 25.0 +/- 1.4, 19.5 +/- 1.9, and 12.2 +/- 2.3 for baseline, 180 BPM, 200 BPM, and 220 BPM, respectively). Atrial natriuretic peptide concentrations increased significantly at 180 BPM (44.1 +/- 3.0 pg/mL) and 200 BPM (54.8 +/- 5.5 pg/mL), compared with baseline concentration (36.8 +/- 2.6 pg/mL). Dopamine concentration increased significantly at 200 BPM (70.4 +/- 10.4 pg/mL), compared with baseline concentration (44.2 73 pg/mL). Norepinephrine concentrations increased significantly from baseline concentration (451 +/- 46.2 pg/mL) to 678 +/- 69.8, 856 +/- 99.6, and 1,003 +/- 2676 pg/mL at 180, 200, and 220 BPM, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Dogs subjected to ventricular pacing for 9 weeks developed neuroendocrine responses similar to those that develop in humans with more chronic heart failure and, except for epinephrine concentrations, similar to those for dogs subjected to ventricular pacing for < 6 weeks.

Evaluation of a step-counter during treadmill walking in 7-12 year old African-American children.

The primary purpose of this study was to evaluate the accuracy of the Digiwalker step-counter in recording the number of steps by African-American children during level treadmill walking and the accuracy of the Digiwalker when placed inside a pouch at midline rather than when placed at midline of the thigh. A secondary purpose of this study was to examine the relationship between the number of steps and physiological response to walking. Study subjects were a sub-set of thirty-one children recruited from a larger study evaluating the effects of an after school program on cardiovascular risk factors in this population. The Digiwalker was consistent in the steps recorded when time and speed were held constant and the Digiwalker was able to detect increases in steps with small increases in walking speed. In addition, the use of a soft-cased pouch appears to be an appropriate alternate placement site for the Digiwalker.

A Prospective Evaluation of the Effects of a 12-Week Outpatient Exercise Program on Clinical and Behavioral Outcomes in Patients with Epilepsy.

Purpose. We hypothesized that patients randomized to an exercise program would demonstrate a measurable improvement in behavioral outcomes with no adverse clinical outcomes, as compared with control patients.Methods. This randomized, prospective, parallel, and controlled study spanned 12 weeks. Twenty-eight patients were randomized either to participate in a supervised exercise program (Exercise) or to continue their current level of activity with no planned intervention (Control). The Exercise group worked with an exercise physiologist three times per week. At specific intervals, behavioral (QOLIE-89, POMS, PSDQ, Self-Esteem) and clinical (seizure activity, antiepileptic drug (AED) concentrations) outcomes were measured.Results. Twenty-three patients completed the study (Exercise n = 14, Control n = 9). Of the four patients in the Exercise group with active seizures, two had no change, one had an increase, and one had a decrease in seizure activity. Of the three patients in the Control group with active seizures, one had no change, one had an increase, and one had a decrease in seizure activity. In all patients, there was <26% coefficient of variation in AED concentrations over the 12-week study, suggesting little or no impact of the exercise intervention. The overall quality of life and two domain scores improved from baseline to Week 12 in the Exercise group (P = 0.031), while the Control group score did not change (P = 0.943). In the Exercise group, there were several measures of physical self-concept and vigor that improved and total mood disturbance decreased from the beginning to the end of the program.Conclusion. This is the first randomized, controlled study of exercise in patients with epilepsy. Behavioral outcomes are positively influenced by moderate exercise and there is no impact on seizure frequency. This suggests that exercise should not be discouraged in the care of epilepsy patients. The ability to offer an exercise program adds a health promotion component to the current plan of care provided by our comprehensive epilepsy program.