The Impact of Blood Flow Restrictive Exercise on Endothelial Function

Blood flow restriction training (BFRT) is the occlusion of blood flow during resistance exercise to elicit enhanced skeletal muscle hypertrophy while lifting lower weights compared to standard resistance training. Research has shown BFR with low intensity resistance training to elicit similar results in skeletal muscle hypertrophy when compared to higher intensity resistance exercise. Although BFR demonstrates similar levels of skeletal muscle hypertrophy, no research has examined the effects of BFR exercise on brachial artery endothelial function which has been demonstrated to be closely linked to coronary artery endothelial function and thus predisposition to developing atherosclerosis. Due to the effect on endothelial function, this type of training modality may not be suitable for individuals with cardiovascular disease (CVD) or those at a greater risk for developing CVD. The purpose of this study is to examine the effects of blood flow restriction training on endothelial function. Subjects were 9 healthy males, 23.9±1.2 years, 27.7±1.2 kg/m 2 who regularly participate in resistance training exercises at least 2 times per week. Subjects performed 3 sets of bicep curls at 30% of their 1 repetition maximum to failure with a blood pressure cuff at 80% arterial occlusion pressure. Endothelial function was assessed by flow mediated dilation performed before, immediately after, and one hour post BFR. These data indicate BFR exercise does not alter endothelial function in healthy males. Given that studies have demonstrated that an acute bout of traditional resistance training increases flow mediated dilation, BFR may be impairing the ability of exercise to improve endothelial function. Future studies will be aimed at examining plasma markers of vascular dysregulation, such as endothelin-1 and vascular cell adhesion molecule in response to BFR to determine potential mechanisms for the blunted flow mediated dilation.https://digitalcommons.odu.edu/education_darden/1006/thumbnail.jp

The Impact of Muscular Strength on Cardiovascular Disease Risk Factors

The purpose of this study was to determine the associations between isokinetic leg muscular strength and cardiovascular disease (CVD) risk factor characterizations in Americans aged 50 and older. Using a publicly available dataset from the National Health and Nutrition Examination Survey (NHANES), a secondary analysis was conducted on participants (males ≥50 yrs; females ≥55 yrs; N=10,858) pooled from 1999 to 2002. CVD risk factors were determined using the American College of Sports Medicine (ACSM) cutoff values. CVD risk factor characterization was determined by creating CVD risk factor profiles (i.e., the total number of CVD risk factors an individual possesses), then separating participants into low (0-2 CVD risk factors), moderate (3-5), and high (6-8) risk groups. Muscular strength was determined by isokinetic maximal peak force (PF) of the leg extensors, both raw and normalized to body mass. Normalized, but not raw, muscular strength was shown to be significantly inversely associated with CVD risk factor characterization for both males and females (Phttps://digitalcommons.odu.edu/gradposters2022_education/1002/thumbnail.jp

Using Neonatal Skin to Study the Developmental Programming of Aging

Numerous studies have examined how both negative and positive maternal exposures (environmental contaminants, nutrition, exercise, etc.) impact offspring risk for age-associated diseases such as obesity, type 2 diabetes, hypertension, and others. The purpose of this study was to introduce the foreskin as a novel model to examine developmental programming in human neonates, particularly in regard to adipogenesis and insulin receptor signaling, major contributors to age-associated diseases such as obesity and diabetes. Neonatal foreskin was collected following circumcision and primary dermal fibroblasts were isolated to perform adipocyte differentiation and insulin stimulation experiments. Human neonatal foreskin primary fibroblasts take up lipid when stimulated with a differentiation cocktail and demonstrate insulin signaling when stimulated with insulin. Thus, we propose that foreskin tissue can be used to study developmental exposures and programming that occur in the neonate as it relates to age-associated diseases such as obesity and diabetes

A Single Bout of Breast Milk Expression Does Not Increase Resting Metabolic Rate

Introduction: Breastfeeding women have elevated resting metabolic rate (RMR); however, whether a single bout of lactation increases RMR is unknown. This study aimed to determine if a single bout of lactation acutely increased RMR. Methods: Twenty-two lactating women (age: 31 ± 0.9 year, body mass index: 27.3 ± 1.2 kg/m2) were recruited. RMR was assessed at baseline and at 1- and 2-h following breast milk expression. Results: RMR was unchanged in lactating women following a single bout of lactation (baseline: 1437 ± 39; 1 h: 1425 ± 37 2 h: 1440 ± 31 kcal/day) (p \u3e .05). RMR was not correlated to daily milk produced (r = 0.05, p \u3e .05), but was correlated to body mass (r = 0.74, p \u3c .001), fat-free mass (kg) (r = 0.61, p \u3c .01), and fat mass (kg) (r = 0.71, p \u3c .01). Conclusion: RMR in lactating women appears to be more related to body mass or composition in the postpartum period rather than lactation

Short-Term Removal of Exercise Impairs Glycemic Control in Older Adults: A Randomized Trial

Postprandial glycemia (PPG) predicts cardiovascular disease, and short-term physical inactivity increases PPG in young, active adults. Whether this occurs in older, active adults who may be more prone to bouts of inactivity is unknown. This study determined if postprandial interstitial glucose (PPIG) was impaired in active older adults following the removal of exercise for 3 days (NOEX) compared to active young adults. In this randomized, crossover study, 11 older (69.1 ± 1.9 years) and 9 young (32.8 ± 1.8 years) habitually active (≥90 min/week of exercise) adults completed 3-days of NOEX and 3-days of normal habitual exercise (EX), separated by ≥1 week. Diet was standardized across phases. Glycemic control (3-day average) was assessed via continuous glucose monitoring during both phases. Significant main effects of age and phase were detected (p \u3c 0.05), but no interaction was found for steps/day (p \u3e 0.05) (old EX: 6283 ± 607, old NOEX: 2380 ± 382 and young EX: 8798 ± 623, young NOEX: 4075 ± 516 steps/day). Significant main effects of age (p = 0.002) and time (p \u3c 0.001) existed for 1-h PPIG, but no effect of phase or interactions was found (p \u3e 0.05). Significant main effects (p \u3c 0.05) of age (old: 114 ± 1 mg/dl, young: 106 ± 1 mg/dl), phase (NOEX: 112 ± 1 mg/dl, EX: 108 ± 1 mg/dl), and time (0 min: 100 ± 2, 30 min: 118 ± 2, 60 min: 116 ± 2, 90 min: 111 ± 2, 120 min: 108 ± 2 mg/dl) in 2-h PPIG were detected, but no interaction was found (p \u3e 0.05). However, only significant main effects of phase (NOEX: 14 ± 1 and EX:12 ± 1, p \u3e 0.05) were found for 24-h blood glucose standard deviation. Older adults appear to have impaired glycemic control compared to young adults and exercise removal impairs glycemic control in both populations. Yet, the impairment in glycemic control with exercise removal is not different between old and young adults

Increased Birth Weight is Associated with Altered Gene Expression in Neonatal Foreskin

Elevated birth weight is linked to glucose intolerance and obesity health-related complications later in life. No studies have examined if infant birth weight is associated with gene expression markers of obesity and inflammation in a tissue that comes directly from the infant following birth. We evaluated the association between birth weight and gene expression on fetal programming of obesity. Foreskin samples were collected following circumcision, and gene expression analyzed comparing the 15% greatest birth weight infants (n = 7) v. the remainder of the cohort (n = 40). Multivariate linear regression models were fit to relate expression levels on differentially expressed genes to birth weight group with adjustment for variables selected from a list of maternal and infant characteristics. Glucose transporter type 4 (GLUT4), insulin receptor substrate 2 (IRS2), leptin receptor (LEPR), lipoprotein lipase (LPL), low-density lipoprotein receptor-related protein 1 (LRP1), matrix metalloproteinase 2 (MMP2), plasminogen activator inhibitor-1 (PAI-1) and transcription factor 7-like 2 (TCF7L2) were significantly upregulated and histone deacetylase 1 (HDAC1) and thioredoxin (TXN) downregulated in the larger birth weight neonates v. controls. Multivariate modeling revealed that the estimated adjusted birth weight group difference exceeded one standard deviation of the expression level for eight of the 10 genes. Between 25 and 50% of variation in expression level was explained by multivariate modeling for eight of the 10 genes. Gene expression related to glycemic control, appetite/energy balance, obesity and inflammation were altered in tissue from babies with elevated birth weight, and these genes may provide important information regarding fetal programming in macrosomic babies

Exposure to PCB126 During The Nursing Period Reversibly Impacts Early-Life Glucose Tolerance

Polychlorinated biphenyls (PCBs) are persistent environmental organic pollutants known to have detrimental health effects. Using a mouse model, we previously demonstrated that PCB126 exposure before and during pregnancy and throughout the perinatal period adversely affected offspring glucose tolerance and/or body composition profiles. The purpose of this study was to investigate the glucose tolerance and body composition of offspring born to dams exposed to PCB126 during the nursing period only. Female ICR mice were bred, and half of the dams were exposed to either vehicle (safflower oil) or 1 µmole PCB126 per kg of body weight via oral gavage on postnatal days (PND) 3, 10, and 17 (n = 9 per group). Offspring body weight, lean and fat mass, and glucose tolerance were recorded every three weeks. PCB126 treatment did not alter dam nor offspring body weight (p \u3e 0.05). PCB126-exposed male and female offspring displayed normal body composition (p \u3e 0.05) relative to vehicle-exposed offspring. However, both male and female offspring that were exposed to PCB126 during the nursing period had significantly impaired glucose tolerance at 3 and 9 weeks of age (p \u3c 0.05). At 6 and 12 weeks of age, no impairments in glucose tolerance existed in offspring (p \u3e 0.05). Our current study demonstrates that exposure to PCB126 through the mother\u27s milk does not affect short- or long-term body composition but impairs glucose tolerance in the short-term

Insulin Mediated Blood Flow Response During Pregnancy

Pregnancy elicits an insulin resistant like state, which appears to be independent of pre-pregnancy health status. The vasculature within skeletal muscle is insulin responsive and insulin mediated vasodilatation of these vessels has been shown to account for up to 40% of glucose uptake. However, it is unknown if impaired insulin mediated vasodilation is a mechanism regulating insulin resistance during pregnancy. Thus, we examined the femoral artery blood flow response via Doppler Ultrasound during an oral glucose tolerance test (75 grams) in 3 pregnant (pre-pregnancy BMI: 26.2±1.7) women and 2 non-pregnant women (BMI:23.1±4.8). The femoral artery blood flow response was not significantly different between the non-pregnant and pregnant women when examining absolute and percent change to peak blood flow (p\u3e0.05). Thus, in this small pilot study, it appears that insulin mediated blood flow is not regulating the impaired glucose tolerance in pregnant women. However, given that currently in this study we have only recruited 3 pregnant and 2 non-pregnant women, future studies aim to bolster these numbers

THE EFFECTS OF SHORT-TERM EXERCISE REMOVAL ON FLOW-MEDIATED DILATION IN YOUNGER AND OLDER ADULTS

BACKGROUND: Endothelial function is negatively associated with decreased risk of cardiovascular disease. Our lab previously demonstrated that young, active adults experience impaired endothelial function following 5 days of physical inactivity. Whether this occurs in older, active adults who may be more prone to bouts of inactivity is unknown. This study determined if endothelial function, as measured by flow-mediated dilation (FMD), was impaired in active, older adults (\u3e55 yr.) following removal of exercise for 5 days compared to active, young adults (18-40yr.). METHODS: Popliteal and brachial artery FMD were measured at baseline and during days 3 (3dNOEX) and 5 (5dNOEX) of removal of exercise in 8 active, older (Age: 67±2.6 yr., BMI: 27±1.5 kg/m2) individuals and 8 active, young (Age: 24±0.9 yr., BMI: 25±1.1 kg/m2) individuals. RESULTS: Steps/day was significantly reduced during removal of exercise in both the young (Bl: 7470.0±974.7, NOEX: 2627.6±338.8) and old (Bl: 6510.7±604.8, NOEX: 3188.2±451.9) subjects (p\u3c0.05). There were no significant main effects of age or time between older and younger subjects on popliteal artery baseline diameter (Young: 5.73±0.41 mm, Old: 5.22±0.41 mm) (Bl: 5.49±0.29 mm, 3dNOEX: 5.47±0.29 mm, 5dNOEX: 5.46±0.29 mm) (p\u3e0.05). However, there was a main effect of time (p=0.02) in popliteal artery %FMD (Bl: 6.44%±0.60, 3dNOEX: 5.71%±0.60, 5dNOEX: 5.00%±0.60) with day 5 being lower than baseline. No main effect of age in popliteal artery %FMD was found (Young: 6.29%±0.75, Old: 5.15%±0.75) (p\u3e0.05). Brachial artery baseline diameter and %FMD was unaltered across age and time (baseline diameter: Young: 4.06±0.21 mm, Old: 3.72±0.21 mm and Bl: 3.90±0.15 mm, 3dNOEX: 3.89±0.15 mm, 5dNOEX: 3.88±0.15 mm) (%FMD: Young: 7.06%±0.86, Old: 6.16%±0.86 and Bl: 7.11%±0.72, 3dNOEX: 6.45%±0.72, 5dNOEX: 6.28%±0.72) (p\u3e0.05). CONCLUSIONS: These preliminary data suggest that %FMD in the popliteal artery is susceptible to impairments following removal of exercise, but that it is not different between older and younger subjects. Future efforts in our laboratory will aim to increase the sample size of each group to ensure that lack of differences between older and younger subjects are not merely due to the small sample size

The Impact of Physical Activity on Polychlorinated Biphenyls in Pregnant Women

Polychlorinated Biphenyls (PCBs) have numerous deleterious effects on pregnant women and their fetus/offspring when exposed in utero. Physical activity has positive health outcomes on pregnant women and offspring. However, studies are lacking on whether physical activity impacts serum PCB levels in pregnant women. This secondary data analysis of the 1994-2004 National Health and Nutrition Examination Survey examined if participating in moderate and vigorous physical activity, as assessed by questionnaire, in 181 pregnant women, impacted PCB levels. Lipid-adjusted PCB 138, 153, and 180 were assessed and related covariates (age, weight change over the previous year, and body mass index (BMI)) were determined. 32 and 82 individuals reported participating in vigorous and moderate physical activity, respectively. PCB 138, 153, and 180 were significantly higher in those who reported participating in vigorous activity (Vig) compared to no vigorous (NoVig) activity (PCB 138:Vig-13.83±0.91, NoVig-11.48±0.72 ng/g, p=0.02; PCB153: Vig-21.06±3.31, NoVig-15.20±1.14 ng/g, p=0.02; PCB 180: Vig-13.26±2.31, NoVig-8.62±0.71ng/g, p=0.06). PCB 138, 153, and 180 were not significantly different in those who reported participating in moderate activity (Mod) compared to no moderate activity (NoMod) (PCB 138: Mod-12.53±0.97, NoMod-11.24±1.14 ng/g, p=0.42; PCB153: Mod-17.35±1.78, NoMod-15.04±1.67 ng/g, p=0.38; PCB 180: Mod-10.26±1.20, NoMod-8.55±1.13 ng/g, p=0.33). After adjusting for age, weight change status, and BMI, PCB levels for both vigorous and moderate activity status were not statistically significant (p\u3e0.05). Vigorous, but not moderate physical activity may be a better predictor of elevated PCB levels in pregnant women; however, after adjusting for relevant covariates this significance no longer remains