Effect of 6-month high-impact step aerobics and resistance training on BMD and tibial bending strength in sedentary premenopausal women.

The rationale of this study was to examine the effectiveness of 6-month high-impact step aerobics (SA) or moderate-intensity resistance training exercise (RT) on bone mineral density (BMD) and bone bending strength in sedentary women. Results show that SA enhanced BMD in the heel, lower leg, and lumbar spine 2. INTRODUCTION: To determine the effectiveness of 6 months of high-impact step aerobics (SA) or moderate-intensity resistance training (RT) on areal bone mineral density (aBMD) and tibial bending strength in sedentary premenopausal women. METHODS: Sixty-nine women (20-35 years old) who were randomly assigned to RT (n = 22), SA (n = 26), or non-treatment control (CON, n = 21) groups completed the study. SA had a minimum of 50 high-impact landings each training session. RT had a periodized lower body resistance training program incorporating eight exercises (65-85% of 1 repetition maximum: 1-RM). Both RT and SA met 3 times weekly. aBMD was assessed using dual X-ray absorptiometry (DXA). Tibial bending strength was assessed using mechanical response tissue analysis (MRTA). Measurements at 6 months were compared to baseline using ANCOVA, adjusted for baseline measures and covariates with α = 0.05. RESULTS: Calcaneus aBMD (0.0176 vs -0.0019 or -0.0009 g/cm2 relative to RT, p < 0.004, and CON, p < 0.006, respectively), lower leg aBMD (0.0105 vs -0.0036 g/cm2, relative to RT, p = 0.02), and lumbar spine 2 (L2) aBMD (0.0082 vs -0.0157 g/cm2 relative to CON, p < 0.02) were significantly greater in the SA group after 6 months. Tibial bending strength and bone resorption biomarkers were unchanged in all three groups after 6 months. CONCLUSION: Sedentary premenopausal women engaging in 6 months of high-impact aerobic exercise improved aBMD in the calcaneus, lower leg, and L2.

Effect of high-impact aerobics and strength training on BMD in young women aged 20-35 years.

To evaluate the effects of a 12-month exercise intervention using either high-impact step aerobic exercise or moderate-intensity strength training on areal bone mineral density (aBMD) we studied 51 untrained women, aged 20-35 years, for this study. Whole body and heel and wrist aBMD were measured by dual-energy X-ray absorptiometry (DXA, Hologic or PIXI Lunar). Subjects were randomly assigned to: impact-loaded step aerobic exercise (SA, n=15), moderate-intensity lower body strength training (ST, n=16) or non-exercise control (CON, n=20). Data analysis only included those who completed 95% of each training routine and attended at least 80% of all sessions. Group differences in aBMD, leg press strength and urinary cross-link deoxypridinoline (µDPD) were analysed using analysis of variance. After a 12-month intervention, the SA elicited an increase in aBMD of the heel (4.4%, p<0.05) and leg press strength (15%, p<0.05), relative to baseline. Meanwhile, the ST showed an increase in leg press strength (48%, p<0.05) with no significant increase in aBMD at any measured site. Similar and unchanged µDPD was observed in all 3 groups at baseline, 6 and 12 months. In conclusion, a 12-month high-impact step aerobic exercise resulted in a significant increase in the heel aBMD in untrained young women, who complied with the exercise regimen. A moderate intensity strength training intervention of similar duration had no effect on aBMD although leg strength increased significantly.

Abdominal obesity and the spectrum of global cardiometabolic risks in US adults.

OBJECTIVE: To compare the association of obesity and abdominal obesity with cardiometabolic risk factor burden and global estimated coronary heart disease (CHD) risk among multiethnic US adults. DESIGN: Cross-sectional, survey study. SUBJECTS: A total of 4456 participants (representing 194.9 million adults) aged 20-79 years in the 2003-2004 National Health and Nutrition Examination Survey (NHANES). MEASUREMENTS: Body mass index (BMI) and waist circumference (WC) measures, CHD risk factors and a 10-year estimated CHD risk based on Framingham algorithms. Obesity was defined as a BMI >or=30 kg/m(2) and abdominal obesity as a WC >88 cm in women and >102 cm in men. High CHD risk status included diabetes, cardiovascular disease (CVD) or a 10-year Framingham risk score of >20%. RESULTS: Overall, abdominal obesity was present in 42.3% of men and 62.5% of women and in 53.6% of whites, 56.9% of blacks and 50.5% of Hispanics (P<0.001 between gender and ethnicity). However, using International Diabetes Federation (IDF)-recommended WC cut points for Hispanics, the prevalence of abdominal obesity was 78.3%. Mean levels of low-density lipoprotein cholesterol (LDL-C), systolic and diastolic blood pressure, fasting glucose and C-reactive protein increased, and high-density lipoprotein cholesterol (HDL-C) decreased (P<0.001) according to BMI and WC categories, although these associations were attenuated in blacks for blood pressure, LDL-C, HDL-C and triglycerides. Of those with high WC, 25-35% had >or=3 cardiometabolic risk factors. High CHD risk among those with high WC was most common in men (27.9%) and non-Hispanic whites (23.9%). Persons with a high vs normal WC, adjusted for age, gender, ethnicity and BMI were more likely to have >or=3 cardiometabolic risk factors (odds ratio (OR)=5.1, 95% confidence interval (CI)=3.9-6.6) and were classified as high CHD risk (OR=1.5, 95% CI=1.1-2.0). CONCLUSION: The association of abdominal obesity with risk factors varies by ethnicity and is independently associated with high CHD risk status, further validating its clinical significance.

Television viewing and pediatric hypercholesterolemia.

Cholesterol screening for children is recommended currently only for those with a family history of premature coronary heart disease or hyperlipidemia. The authors report on a pediatric-office-based cholesterol screening program where the predictive values of family history indicators were evaluated along with reported television viewing, physical activity, and dietary habits in 1081 children (aged 2 to 20 years, mean 7.4 +/- 3.6 [SD] years). Eight percent of these children had a total cholesterol value of 200 mg/dL or higher; 53% of such children reported watching 2 or more hours of television daily compared with 34% of children with lower cholesterol levels. Multivariate analyses revealed that excessive television viewing was the strongest predictor for a child to have a cholesterol value of 200 mg/dL or higher, with relative risks of 2.2 for 2 to 4 hours of television viewing per day (P less than .01) and 4.8 for children watching more than 4 hours/day, when compared to those watching less than 2 hours/day (P less than .01). In contrast, a positive family history of a high cholesterol level was only modestly associated with an increased probability of having a high cholesterol level (relative risk = 1.6, P less than .05), and a history of premature myocardial infarction in a parent or grandparent was not associated with a child's cholesterol level. Excessive television viewing was found to be associated with certain dietary and physical activity habits and may prove to be a useful, global marker for several life-style factors predisposing children to hypercholesterolemia.

Relationship of blood lipids to anthropometric measures and family medical history in an ethnically diverse school-aged population.

High total cholesterol is an important risk factor for coronary heart disease, and high levels in adulthood can be linked to high levels in childhood. We evaluated total cholesterol and lipoprotein levels and their relationship to body composition and reported family medical history of premature myocardial infarction or high total cholesterol in 800 children, aged 10 to 13, of Hispanic (n = 612), Asian (n = 100), and white or other (n = 88) ethnic descent. Mean total cholesterol levels were similar among boys (168.6 mg/dL; n = 399) and girls (167.5 mg/dL; n = 401) and among ethnic groups; however, high-density lipoprotein cholesterol was highest in boys and in Asian children. Forty-six percent of all children tested had total cholesterol levels of 170 mg/dL or greater (13.4% were 200 mg/dL or higher). Body mass index and skinfold (triceps and subscapular) measurements were least in Asian children. A high prevalence of obesity was noted in white and Hispanic children. Body mass index was positively correlated with total cholesterol in Hispanic children; in all ethnic groups, body mass index was positively associated with triglyceride levels and negatively associated with high-density lipoprotein cholesterol. Skinfold measurements were also significantly correlated with total cholesterol (in Hispanic children) and triglycerides and were negatively associated with high-density lipoprotein cholesterol. Among children with family history data available, only 52% with a low-density lipoprotein cholesterol level of 130 mg/dL or higher had a reported family history of high total cholesterol or myocardial infarction in a parent or grandparent aged 55 or younger, although rates varied substantially by ethnic group. The present study demonstrates the importance of population-based lipid screening in Hispanic, Asian, or multiethnic children, where more than a third of the children have total cholesterol levels in need of dietary management. The majority of children with elevated total or low-density lipoprotein cholesterol levels will not be identified if screening is recommended on the basis of a positive family history alone. Finally, there is evidence that body composition in children may be more closely correlated with total cholesterol or lipoprotein levels in certain ethnic groups.

Relationship of performance on motor activities and reading achievement.

The purpose of this study was to investigate the influence of specific motor activities on elementary school-aged children's reading achievement. The subjects were 33 boys and 33 girls in Grade 2 enrolled in the regular program. They were separated equally into one of three groups: Experimental group 1 participated in Frostig activities, Experimental group 2 read books selected for their grade level, while a control group followed the traditional school routine. The two experimental groups were children from predominantly Mexican-American descent; the control group was primarily of Caucasian descent. During the 20-wk. period, the subjects met with their respective group three times per week in 1/2-hr. sessions. The first and second experimental groups showed no significant improvement in reading achievement. It was concluded that the added motor activities did not enhance reading achievement.