Influence of Obesity on the Relationship of Cardiometabolic Risks Factors With Cardiovascular Disease in Older African and European Americans.

PURPOSE: This study evaluated the impact of obesity on cardiometabolic risk factors (CRF) interrelationships and predictive efficiency of CVD development in older African (AA) and European Americans (EA). DESIGN: A comparative research design evaluated CRF risk profile differences between participant groups. SETTING: Seven neighborhoods in a southern US city. SUBJECTS: A sample of 179 older AA (n = 128) and EA (n = 51) adults. MEASURES: Non-fasting blood samples were evaluated for lipids and lipoproteins, glycosylated hemoglobin, systolic -(SBP) and diastolic blood pressure (DBP), body mass index (BMI), body fat percentage (BF%) and physical function. ANALYSIS: Data were analysis with descriptive statistics, t-tests, and correlations. RESULTS: AA were heavier than EA although all had above average age-appropriate fitness. Means and relationships between CRF and other variables were different (P < .05) based on race. Both AA (41.3 + 5.8) and EA (38.6 + 6.4) BF% were CRF risks. Holding BMI constant, CRF were generally not related, and the relationships were different for AA and EA. AA had a range of 13.0 to 27.2% more favorable values for cholesterol, HDL-C, and triglyceride. EA had favorable A1c (EA 5.8 vs AA 6.2%) values. CONCLUSIONS: A limitation of this report is the small sample size. Although further research is warranted, these findings suggest population specific CRF selections would improve CVD prediction in AA.

Cardiometabolic risk factors and cardiovascular disease predictions in older African and European Americans.

Cardiometabolic (CMO) risks factors do not provide similar cardiovascular disease (CVD) predictions in young African (AA) and European Americans (EA) adults. Whether CMO risk predictions contribute to this disparity in older adults is unclear. We hypothesize that older AA CMO clustering pattern will be different from EA clustering patterns when determine with non-fasting lipid and lipoproteins. The participants were 106 older adults (66 AA and 40 EA) from a working/middle class neighborhood (income $46,364 - $80,904) in an urban North Carolina community. The participants were evaluated for CMO risk factors (total cholesterol, high- (HDL) and low-density lipoproteins (LDL), triglyceride (TG), glycosylated hemoglobin (HbA1c), systolic -SBP- and diastolic blood pressures -DBP), body mass index (BMI), body fat % (BF%) and timed up and go test (assessed falls risk and physical function). The AA participants were heavier, had higher BMI, BF%, and timed up and go values (p < 0.01). The data were evaluated for differences (t-test) and Pearson correlations for relationships. If data differ by p < 0.05 the data were significantly different. The AA had a 17.6 % higher HDL (64.7 vs 55.1 mg/dL - p < 0.05) and 7.6 % higher HbA1c (5.8 vs 5.4 % - p < 0.01) than EA. Higher HDL values in EA indicate lower CVD risks. The HDL paradox for AA (AA had higher HDL values, but greater CVD risks) was observed and the HbA1c difference may be misleading, as similar glucose values in AA tend to have higher HbA1c values. Lipid, lipoprotein, and blood pressure was not different between the races. AA had higher body composition and HDL values. Although future research on this topic with larger samples, dietary data and detailed descriptions of participations medications is warranted to validate findings from this study. These data suggest older AA and EA adults with similar environmental conditions have similar CMO risks when measures with none fasting blood samples. Since AA have a greater prevalence of CVD, these finding suggests that population specific CMO risk factor clustering may be more effective predictors of CVD for AA.

Sleep and Risk for Metabolic Syndrome, Hypertension, Diabetes and Obesity Among Community-Dwelling Older Adults.

Older adults often face a variety of health problems that are found less frequently in younger populations. Metabolic syndrome and other related diseases are common due to a variety of age and lifestyle factors. Sleep, often operationalized only as duration, quality, or apnea diagnosis, is associated with worse health outcomes across the lifespan. However, sleep is multi-faceted and may require a collection of measures in order to reflect this. This study examined a suite of self-reported sleep habits (risk for sleep apnea, night time duration, nap duration, quality, timing, and consistency of duration and timing) and physiological data in a sample of 144 older adults. Sleep-related variables as a group predicted risk for metabolic syndrome, hypertension, and diabetes but was not a clear predictor of obesity. Of the individual measures, risk for apnea and consistency of sleep duration throughout the week predicted risk for metabolic syndrome (apnea b = .64, p < .05; duration inconsistencies b = .22, p < .05). The findings of the study suggest that greater consistency in sleep schedules may benefit the health of older adult populations' risk for these disorders.

Differential gene expression in high- and low-active inbred mice.

Numerous candidate genes have been suggested in the recent literature with proposed roles in regulation of voluntary physical activity, with little evidence of these genes' functional roles. This study compared the haplotype structure and expression profile in skeletal muscle and brain of inherently high- (C57L/J) and low- (C3H/HeJ) active mice. Expression of nine candidate genes [Actn2, Actn3, Casq1, Drd2, Lepr, Mc4r, Mstn, Papss2, and Glut4 (a.k.a. Slc2a4)] was evaluated via RT-qPCR. SNPs were observed in regions of Actn2, Casq1, Drd2, Lepr, and Papss2; however, no SNPs were located in coding sequences or associated with any known regulatory sequences. In mice exposed to a running wheel, Casq1 (P = 0.0003) and Mstn (P = 0.002) transcript levels in the soleus were higher in the low-active mice. However, when these genes were evaluated in naïve animals, differential expression was not observed, demonstrating a training effect. Among naïve mice, no genes in either tissue exhibited differential expression between strains. Considering that no obvious SNP mechanisms were determined or differential expression was observed, our results indicate that genomic structural variation or gene expression data alone is not adequate to establish any of these genes' candidacy or causality in relation to regulation of physical activity.

Physical activity preferences for low-income sedentary urban African American older adults.

The objective of this study was to determine (a) activity preferences for low-income sedentary urban African American older adults and (b) information needed to deliver a lay physical activity intervention in the community for this population. This descriptive qualitative study used six focus groups. Participants were African American, 55 and older, had low incomes, and had sedentary behavior. Physical activity themes included excitement/emotion for physical activity, group physical activity, and location of physical activity. Themes regarding aspects of being a lay community health worker included beneficial service, uncertainty, logistics concerns, and delivery method preferences. The findings from this study will provide the basis for an intervention for low-income sedentary African American older adults. Preferences for physical activity, concerns about and supports needed for individuals to serve as lay community health workers, various types of training materials, and preferred technology for physical activity participation are identified and discussed.

Effects of Supraphysiological Doses of Sex Steroids on Wheel Running Activity in Mice.

The regulatory mechanisms of physical activity are postulated to include environmental and biological/genetic factors. In particular, the sex steroids appear to have profound effects on wheel running in rodents. The purpose of this project was to investigate the effects of 17ß-estradiol and testosterone on wheel running distance, duration, and speed in male and female C57BL/6J mice. The mice (N=46) were provided free access to running wheels interfaced with computers to track daily running distance, duration, and speed. Activity was assessed at baseline in intact mice, after surgical gonadectomy, and after replacement with either 17ß-estradiol or testosterone. Upon removal of the gonads, physical activity levels were significantly reduced in both males and females. Distance (10-30% of baseline) and duration (20-47% of baseline) measures were most affected by the loss of endogenous steroids, while running speed (60-77% of baseline) though significantly reduced-decreased by a much lower magnitude. Testosterone replacement fully recovered running distance, duration, and speed to pre-surgical levels in both sexes (100% of baseline). Distance (30-42% of baseline) and duration (43-47% of baseline) were partially recovered by 17ß-estradiol, but not to baseline levels. Speed (100% of baseline) was fully recovered by 17ß-estradiol replacement in males and females. This study suggests that physical activity in mice is affected by endogenous steroids and can be altered by exogenous steroid replacement. The differences in the recovery abilities of 17ß-estradiol and testosterone suggest that both estrogenic and androgenic pathways may be involved to variable degrees in activity regulation.

Driven to be inactive? The genetics of physical activity.

The health implications of physical inactivity, including its integral role in promoting obesity, are well known and have been well documented. Physical activity is a multifactorial behavior with various factors playing a role in determining individual physical activity levels. Research using both human and animal models in the past several years has clearly indicated that genetics is associated with physical activity. Furthermore, researchers have identified several significant and suggestive genomic quantitative trait loci associated with physical activity. To date, the identities of the causal genes underlying physical activity regulation are unclear, with few strong candidate genes. The current research provides a foundation from which future confirmatory research can be launched as well as determination of the mechanisms through which the genetic factors act. The application of this knowledge could significantly augment the information available for physical activity behavior change interventions resulting in more efficient programs for those predisposed to be inactive.

Strain screen and haplotype association mapping of wheel running in inbred mouse strains.

Previous genetic association studies of physical activity, in both animal and human models, have been limited in number of subjects and genetically homozygous strains used as well as number of genomic markers available for analysis. Expansion of the available mouse physical activity strain screens and the recently published dense single-nucleotide polymorphism (SNP) map of the mouse genome (approximately 8.3 million SNPs) and associated statistical methods allowed us to construct a more generalizable map of the quantitative trait loci (QTL) associated with physical activity. Specifically, we measured wheel running activity in male and female mice (average age 9 wk) in 41 inbred strains and used activity data from 38 of these strains in a haplotype association mapping analysis to determine QTL associated with activity. As seen previously, there was a large range of activity patterns among the strains, with the highest and lowest strains differing significantly in daily distance run (27.4-fold), duration of activity (23.6-fold), and speed (2.9-fold). On a daily basis, female mice ran further (24%), longer (13%), and faster (11%). Twelve QTL were identified, with three (on Chr. 12, 18, and 19) in both male and female mice, five specific to males, and four specific to females. Eight of the 12 QTL, including the 3 general QTL found for both sexes, fell into intergenic areas. The results of this study further support the findings of a moderate to high heritability of physical activity and add general genomic areas applicable to a large number of mouse strains that can be further mined for candidate genes associated with regulation of physical activity. Additionally, results suggest that potential genetic mechanisms arising from traditional noncoding regions of the genome may be involved in regulation of physical activity.

Repeatability of exercise behaviors in mice.

PURPOSE: Measurements of exercise behaviors in rodents such as maximal treadmill endurance and physical activity are often used in the literature; however, minimal data are available regarding the repeatability of measurements used for these exercise behaviors. This study assessed the repeatability of a commonly used maximal exercise endurance treadmill test as well as voluntary physical activity measured by wheel running in mice. METHODS: Repeatability of treadmill tests were analyzed for both inbred and outbred mice in addition to a 10 week repeatability analysis using Balb/cJ mice (n=20). Voluntary daily physical activity was assessed by distance, duration, and speed of wheel running (WR). Physical activity measurements on days 5 and 6 of WR in a large cohort (n=739) of both inbred and outbred mice were compared. RESULTS: No significant differences (p>0.05) in exercise endurance were found between different cohorts of Balb/cJ and DBA/2J mice indicating strains overall generally test the same; however, significant differences between tests were seen within BaD2F(2) animals (p<0.001). Bland-Altman analysis revealed a lack of agreement between weekly endurance tests within mouse, and correlation analysis showed lack of consistent correlations between weekly endurance tests within mouse. No significant differences were found for WR measurements within mouse between days (p=0.99). High correlations between days within mouse for WR were found (r=0.74-0.85). CONCLUSIONS: High intra-mouse variability between repeated endurance tests suggests that treadmill testing in an enclosed chamber with shock grid for motivation to run in mice is not repeatable. Conversely, high correlation and agreement between days of wheel-running measurements suggest that voluntary activity (WR) is repeatable and stable within individual mice.

An evidence-based exercise program implemented in congregate-meal sites.

BACKGROUND: This study examined the feasibility of implementing the EnhanceFitness Program (formerly Lifetime Fitness Program), an evidence-based exercise program, at congregate-meal sites that generally serve low-income older adults. METHODS: A 12-week aerobic and strength training exercise program was held at senior centers 3 times a week. RESULTS: The mean age of the 31 participants was 73.5 years+/-6.7 years (60-86). Participants' compliance with attending the exercise class was 74%. Paired t tests were used to evaluate change after the intervention. Three out of six components of the Senior Fitness Test increased significantly after the exercise intervention (P<.003). Three out of the eight self-reported health concepts of the SF-36 demonstrated significant improvement after the exercise intervention (P<.003). CONCLUSION: These data indicate that an evidence-based exercise program can be successfully implemented in this population.

The effects of aerobic training and nutrition education on functional performance in low socioeconomic older adults.

PURPOSE: To describe the population in terms of risk for disability and compare the effects of a walking intervention and nutrition education intervention on risk modification and functional performance in lower socioeconomic older adults using a randomized controlled study. METHODS: Twenty-six community-dwelling older adults aged 60 and older were randomly assigned to a 16-week walking exercise group or a nutrition education control group. Peak aerobic capacity and physical function were measured at baseline and post intervention. Physical function was measured using the Medical Outcomes Study Short Form Health Survey Physical Function subscale, Short Physical Performance Battery, Physical Performance Test, and Continuous Scale Physical Functional Performance 10 item test (CS-PFP10). RESULTS: Eighty-five percent of the participants were at risk for preclinical disability of which 50% were at risk for moderate disability. The walking exercise group significantly improved in peak aerobic capacity (18.9%), physical function (25%) using the CS-PFP10 compared to the control group. CONCLUSION: These findings highlight the importance of physical activity and indicate that walking, a simple exercise that can be done without specialized exercise leader or equipment can significantly increase peak aerobic capacity and physical function in just 4 months.