Muscle-to-Bone Ratio in NCAA Division I Collegiate Football Players by Position.

ABSTRACT: Dengel, DR, Studee, HR, Juckett, WT, Bosch, TA, Carbuhn, AF, Stanforth, PR, and Evanoff, NG. Muscle-to-bone ratio in NCAA division I collegiate football players by position. J Strength Cond Res XX(X): 000-000, 2024-The purpose of this study was to compare the muscle-to-bone ratio (MBR) in National Collegiate Athletic Association Division I football players (collegiate football players [CFP]) to healthy, age-matched controls. In addition, we examined MBR in CFP by position. A total of 553 CFP and 261 controls had their total and regional lean mass (LM), fat mass (FM), and bone mineral content (BMC) determined by dual x-ray absorptiometry (DXA). College football players were categorized by positions defined as offensive linemen (OL), defensive linemen (DL), tight end, linebacker (LB), running back (RB), punter or kicker, quarterback (QB), defensive back (DB), and wide receiver (WR). There were significant differences between CFP and controls for total LM (80.1 ± 10.0 vs. 56.9 ± 7.8 kg), FM (22.2 ± 12.5 vs. 15.2 ± 7.1 kg), and BMC (4.3 ± 0.5 vs. 3.1 ± 0.5 kg). Although there were significant differences in body composition between CFP and controls, there was no significant differences in total MBR between CFP and controls (18.6 ± 1.4 vs. 18.8 ± 1.7). Regionally, CFP had significantly lower trunk MBR than controls (26.7 ± 2.7 vs. 28.7 ± 4.2), but no difference was seen in leg or arm MBR. Positional differences in CFP were noted as total MBR being significantly higher in DL (19.0 ± 1.4) than in DB (18.1 ± 1.3), WR (18.1 ± 1.3), and LB (18.2 ± 1.3). OL had a significantly higher total MBR (19.2 ± 1.3) than DB (18.1 ± 1.3), LB (18.2 ± 1.3), QB (18.1 ± 1.0), and WR (18.1 ± 1.3). In addition, RB had significantly higher total MBR (18.8 ± 1.3) than DB (18.1 ± 1.3) and WR (18.1 ± 1.3). This study may provide athletes and training staff with normative values when evaluating total and regional MBR with DXA.

Body Mass Index Trajectories and Biomarkers of Cardiometabolic Risk in Children from Low-Income and Racially and Ethnically Diverse Households.

Background: This study examined the associations between BMI trajectories and emerging cardiometabolic risk (CMR) in children living in low-income and racially and ethnically diverse households in the United States. Methods: Data were drawn from NET-Works randomized intervention trial and NET-Works 2 prospective follow-up study (N = 338). BMI was measured across 6 follow-up visits and biomarkers of cardiometabolic risk (CMR) at the sixth visit. Group-based trajectory modeling identified child BMI trajectories. Adjusted multivariable linear regressions evaluated the associations between BMI trajectories and CMR. Results: We identified two BMI trajectories: 25% followed a trajectory of steep BMI increase, and 75% followed a moderate decreasing BMI trajectory over time. Relative to children in the moderate decreasing trajectory, children in the increasing trajectory had higher adjusted mean levels of C-reactive protein [CRP; 3.3; 95% confidence interval (CI): 1.6 to 5.0], leptin (63.1; 95% CI: 44.3 to 81.8), triglycerides (35.4; 95% CI: 22.1 to 48.6), triglyceride/high-density lipoprotein (HDL) ratio (1.2; 95% CI: 0.8 to 1.6), hemoglobin A1c (HbA1C; 0.1; 95% CI: 0.03 to 0.2), fasting glucose (1.8; 0.1 to 3.5) and insulin (8.8; 95% CI: 6.5 to 11.0), overall CMR score (0.7; 95% CI: 0.5 to 0.9), and lower adiponectin (-1.3; 95% CI: -2.5 to -0.1) and HDL (-10.8; 95% CI: -14.3 to -7.4). Conclusions: Children with high BMIs early in childhood were more likely to maintain an accelerated BMI trajectory throughout childhood, which was associated with adverse CMR in pre-adolescence. To advance health equity and support children's healthy weight and cardiovascular health trajectories, public health efforts are needed to address persistent disparities in childhood obesity and CMR.

Endothelial-derived extracellular vesicles associated with electronic cigarette use impair cerebral microvascular cell function.

The aim of this study was to determine the effect of circulating endothelial cell-derived microvesicles (EMVs) isolated from e-cigarette users on human cerebral microvascular endothelial cells (hCMECs) nitric oxide (NO) and endothelin (ET)-1 production and tissue-type plasminogen activator (t-PA) release. Circulating EMVs (CD144-PE) were isolated (flow cytometry) from 27 young adults (19-25 yr): 10 nonsmokers (6 M/4 F), 10 e-cigarette users (6 M/4 F), and 7 tobacco cigarette smokers (4 M/3 F). hCMECs were cultured and treated with isolated EMVs for 24 h. EMVs from e-cigarette users and cigarette smokers induced significantly higher expression of p-eNOS (Thr495; 28.4 ± 4.6 vs. 29.1 ± 2.8 vs. 22.9 ± 3.8 AU), Big ET-1 (138.8 ± 19.0 vs. 141.7 ± 19.1 vs. 90.3 ± 18.8 AU) and endothelin converting enzyme (107.6 ± 10.1 and 113.5 ± 11.8 vs. 86.5 ± 13.2 AU), and significantly lower expression of p-eNOS (Ser1177; 7.4 ± 1.7 vs. 6.5 ± 0.5 vs. 9.7 ± 1.6 AU) in hCMECs than EMVs from nonsmokers. NO production was significantly lower and ET-1 production was significantly higher in hCMECs treated with EMVs from e-cigarette (5.7 ± 0.8 µmol/L; 33.1 ± 2.9 pg/mL) and cigarette smokers (6.3 ± 0.7 µmol/L; 32.1 ± 3.9 pg/mL) than EMVs from nonsmokers (7.6 ± 1.2 µmol/L; 27.9 ± 3.1 pg/mL). t-PA release in response to thrombin was significantly lower in hCMECs treated with EMVs from e-cigarette users (from 38.8 ± 6.3 to 37.4 ± 8.3 pg/mL) and cigarette smokers (31.5 ± 5.5 to 34.6 ± 8.4 pg/mL) than EMVs from nonsmokers (38.9 ± 4.3 to 48.4 ± 7.9 pg/mL). There were no significant differences in NO, ET-1, or t-PA protein expression or production in hCMECs treated with EMVs from e-cigarette users and smokers. Circulating EMVs associated with e-cigarette use adversely affects brain microvascular endothelial cells and may contribute to reported cerebrovascular dysfunction with e-cigarette use.NEW & NOTEWORTHY In the present study, we determined the effect of circulating endothelial cell-derived microvesicles (EMVs) isolated from e-cigarette users on human cerebral microvascular endothelial cells (hCMECs) nitric oxide (NO) and endothelin (ET)-1 production and tissue-type plasminogen activator (t-PA) release. EMVs from e-cigarette users reduced brain microvascular endothelial cell NO production, enhanced ET-1 production, and impaired endothelial t-PA release. EMVs are a potential mediating factor in the increased risk of stroke associated with e-cigarette use.

Total and Regional Body Composition of NCAA Collegiate Female Rowing Athletes.

This study explored body composition in female NCAA Division I rowers compared to controls; and the effect of season, boat category, and oar side on body composition. This retrospective analysis of 91 rowers, and 173 age, sex, and BMI-matched controls examined total and regional fat mass (FM), lean mass (LM), bone mineral content (BMC), bone mineral density (BMD), percent body fat (%BF), and visceral adipose tissue (VAT) measured using dual X-ray absorptiometry. Two-sample t-testing was used to assess differences between rowers and controls. Repeated measures ANOVA analyzed differences across seasons. ANOVA analyzed differences between boat categories. Paired t-testing analyzed oar side versus non-oar side. Rowers had greater height (174.2; 164.1 cm), weight (75.2; 62.6 kg), LM (51.97; 41.12 kg), FM (20.74; 19.34 kg), BMC (2.82; 2.37 kg), and BMD (1.24; 1.14 g/cm2); but lower %BF (30.5%; 27.1%), and VAT (168.1; 105.0 g) than controls (p<0.05). Total, arm, and trunk muscle-to-bone ratio were greater in rowers (p<0.001). Rowers demonstrated greater arm LM (5.8 kg; 5.6 kg) and BMC (0.37 kg; 0.36 kg) in Spring compared to Fall (p<0.05). 1V8 rowers had a lower %BF than non-scoring rowers (25.7%; 29.0%; p=0.025). No differences observed between oar sides. These findings will help rowing personnel better understand body composition of female collegiate rowers.

Positional Differences in Muscle-to-bone Ratio in National Football League Players.

The purpose of the present study was to examine the muscle-to-bone ratio (MBR) in National Football League (NFL) players. Three hundred and forty-six NFL players had their total body lean, fat and bone masses determined using dual X-ray absorptiometry and were compared to 228 age-matched, healthy male controls. Compared to the control group, NFL players had a significantly lower percent total body fat (17.90±6.92 vs. 22.93±8.96%, p=0.053), but significantly greater total fat mass (19.76±11.29 vs. 17.84±12.11 kg, p<0.0001), lean mass (84.55±8.75 vs. 55.3±11.79 kg, p<0.0001), bone mineral content (4.58±0.45 vs. 2.91±0.67 kg, p<0.0001), and bone mineral density (1.61±0.11 vs. 1.26±0.21 g/cm2, p<0.0001). NFL players had greater arm MBR (17.70±1.47 vs. 16.48±1.88, p<0.0001) than controls; however, both trunk (26.62±2.55 vs. 31.56±4.19, p<0.0001) and total (18.50±1.31 vs. 19.12±1.88, p<0.001) MBR were lower in NFL players. Leg MBR was not significantly different between NFL players and controls (16.72±1.53 vs. 16.85±1.87, p=0.34). When NFL players were categorized by their offensive or defensive position for comparison, no differences in total MBR were observed. However, leg MBR varied greatly among NFL players by position. It is possible that regional differences in MBR in the NFL players may be related to the demands of that position.

No Changes in Body Composition in NCAA Division I Collegiate Football Players because of COVID-19 Restrictions.

ABSTRACT: Czeck, MA, Roelofs, EJ, Evanoff, NG, and Dengel, DR. No Changes in body composition in NCAA Division I Collegiate Football Players due to COVID-19 restrictions. J Strength Cond Res 36(6): 1749-1752, 2022-The purpose of this study was to explore the impact of coronavirus disease 2019 (COVID-19) restrictions on body composition, assessed by dual x-ray absorptiometry (DXA), between the 2020 postseason (pre-COVID-19 restrictions) and the 2021 postseason (post-COVID-19 restrictions) in collegiate football players (n = 50). In addition, a subset of athletes (n = 23) was used to explore body composition variables across 4 postseason time points. Body composition variables assessed were total and regional body fat percent, total mass, lean mass, fat mass, bone mineral content, bone mineral density, and visceral adipose tissue mass. Paired t-tests were used to determine differences between the 2020 postseason and the 2021 postseason in body composition variables. Analysis of variance with Tukey HSD post hoc tests assessed significant differences in total and regional body composition across 4 years while adjusting for multiple comparisons. There were no significant differences (p > 0.05) between postseason 2020 and postseason 2021 for all measures of body composition. In a subset of athletes, body composition was analyzed over a 4-year period of time. There were no significant differences between all 4 time points for all measures of body composition. In conclusion, body composition variables in this study's subjects were not affected because of coronavirus disease 2019 restrictions or over 4 years of their collegiate football career.

Relationship of Circulating Endothelial Cells With Obesity and Cardiometabolic Risk Factors in Children and Adolescents.

Background Circulating endothelial cells (CECs) reflect early changes in endothelial health; however, the degree to which CEC number and activation is related to adiposity and cardiovascular risk factors in youth is not well described. Methods and Results Youth in this study (N=271; aged 8-20 years) were classified into normal weight (body mass index [BMI] percentage <85th; n=114), obesity (BMI percentage ≥95th to <120% of the 95th; n=63), and severe obesity (BMI percentage ≥120% of the 95th; n=94) catagories. CEC enumeration was determined using immunohistochemical examination of buffy coat smears and activated CEC (percentage of vascular cell adhesion molecule-1 expression) was assessed using immunofluorescent staining. Cardiovascular risk factors included measures of body composition, blood pressure, glucose, insulin, lipid profile, C-reactive protein, leptin, adiponectin, oxidized low-density lipoprotein cholesterol, carotid artery intima-media thickness, and pulse wave velocity. Linear regression models examined associations between CEC number and activation with BMI and cardiovascular risk factors. CEC number did not differ among BMI classes (P>0.05). Youth with severe obesity had a higher degree of CEC activation compared with normal weight youth (8.3%; 95% CI, 1.1-15.6 [P=0.024]). Higher CEC number was associated with greater body fat percentage (0.02 per percentage; 95% CI, 0.00-0.03 [P=0.020]) and systolic blood pressure percentile (0.01 per percentage; 95% CI, 0.00-0.01 [P=0.035]). Higher degree of CEC activation was associated with greater visceral adipose tissue (5.7% per kg; 95% CI, 0.4-10.9 [P=0.034]) and non-high-density lipoprotein cholesterol (0.11% per mg/dL; 95% CI, 0.01-0.21 [P=0.039]). Conclusions Methods of CEC quantification are associated with adiposity and cardiometabolic risk factors and may potentially reflect accelerated atherosclerosis as early as childhood.

Re-Opening Exercise Science Laboratories and Testing During the Covid-19 Endemic Phase.

The coronavirus disease 2019 (COVID-19) pandemic has forced primary/grade schools and university closings as well as forced the suspension of a number of medical and laboratory testing procedures. Exercise science laboratories whether in clinical, research or educational locations were also forced to pause testing procedures. As the COVID-19 pandemic begins to subside in some areas of the world, exercise science laboratories are contemplating how to create a safe environment to resume some laboratory testing activities. In this article, we present suggestions for how exercise science laboratories can open and create a safe environment for subjects, laboratory personnel and equipment upon reopening.

Feasibility of intraoperative aortic root imaging in congenital heart surgery.

BACKGROUND: Intraoperative vascular imaging is a useful tool to evaluate coronary ostia in congenital heart patients with suboptimal preoperative imaging findings. Additionally, vascular imaging has potential value for visualization of the ascending aortic intima media thickness (IMT) in certain clinical scenarios. This study sought to evaluate the feasibility of intraoperative vascular imaging of coronary ostia and IMT during congenital heart surgery. METHODS: We describe the technique for performance of intraoperative vascular imaging by a pediatric cardiologist using a high-resolution linear sequential array transducer. RESULTS: Intraoperative vascular imaging was obtained on seven patients. Coronary ostia were normal in all except one. This patient had congenital stenosis of the left coronary ostium discovered during intraoperative imaging and confirmed by the surgeon. In another patient with Williams syndrome, the IMT was noted to be prominent. CONCLUSIONS: It is feasible to perform intraoperative vascular imaging in less than 5 minutes of operator's time and provides superior visualization of the coronary ostia and IMT.

Relationship of Apolipoproteins with Subclinical Cardiovascular Risk in Youth.

OBJECTIVE: To examine the association of apolipoproteins with arterial stiffness and carotid artery structure in children and adolescents. STUDY DESIGN: A total of 338 children and adolescents (178 female) with a mean age 13.0 ± 2.8 years were examined. Apolipoproteins (AI, AII, B100, CII, CIII, and E) were measured via human apolipoprotein magnetic bead panel. Applanation tonometry determined pulse wave velocity and ultrasound imaging measured carotid intima-media thickness. Dual X-ray absorptiometry measured total body fat percent. Linear regression models were adjusted for Tanner stage, sex, and race with further adjustments for body fat percent. Linear regression models also examined the interaction between Tanner stage and apolipoproteins. RESULTS: There was a significant positive association between pulse wave velocity and apolipoproteins: AI (0.015 m/s/10 µg/mL [CI 0.005-0.026], P = .003), AII (0.036 m/s/10 µg/mL [0.017-0.056], P < .001), B100 (0.009 m/s/10 µg/mL [0.002-0.016], P = .012), E (0.158 m/s/10 µg/mL [0.080-0.235], P < .001), and CIII:CII (0.033/µg/mL [0.014-0.052], P < .001). After we added body fat percent to the models, pulse wave velocity (PWV) remained positively associated with greater levels of apolipoproteins: AI, AII, B100, E, and CIII:CII. Both with and without the adjustment for body fat percent, there were no significant associations between any apolipoprotein and carotid intima-media thickness. There were no significant interactions between Tanner stage and apolipoproteins. CONCLUSIONS: These findings suggest that greater levels of apolipoprotein AII, E, and CIII:CII are associated with increased arterial stiffness in children and adolescents, both with and without adjusting for percent body fat. These specific apolipoproteins may be useful as biomarkers of cardiovascular risk.

Abnormally increased carotid intima media-thickness and elasticity in patients with Morquio A disease.

BACKGROUND: Cardiovascular disease frequently causes morbidity and mortality in mucopolysaccharidoses (MPS); however, cardiovascular anatomy and dysfunction in MPS IVA (Morquio A disease) is not well described. Consequently, the study aimed to compare carotid artery structure and elasticity of MPS IVA patients with other MPS patients and healthy control subjects, and quantitate frequency of MPS IVA cardiac structural and functional abnormalities. METHODS: Prospective, multi-center echocardiogram and carotid ultrasound evaluations of 12 Morquio A patients were compared with other MPS and healthy control subjects. Average differences between groups were adjusted for age, sex, and height with robust variance estimation for confidence intervals and P-values. RESULTS: Morquio A patients demonstrated significantly higher (P < 0.001) adjusted carotid intima-media thickness (cIMT), mean (SD) of 0.56 mm (0.03) compared to control subjects, 0.44 mm (0.04). The Morquio A cohort had significantly greater adjusted carotid elasticity (carotid cross-sectional compliance + 43%, P < 0.001; carotid incremental elastic modulus - 33%, P = 0.003) than control subjects and other MPS patients. Aortic root dilatation was noted in 56% of the Morquio A cohort, which also had highly prevalent mitral (73%) and aortic (82%) valve thickening, though hemodynamically significant valve dysfunction was less frequent (9%). CONCLUSIONS: Increased carotid elasticity in Morquio A patients is an unexpected contrast to the reduced elasticity observed in other MPS. These Morquio A cIMT findings corroborate MPS IVA arterial post-mortem reports and are consistent with cIMT of other MPS. Aortic root dilatation in Morquio A indicates arterial elastin dysfunction, but their carotid hyperelasticity indicates other vascular intima/media components, such as proteoglycans, may also influence artery function. Studying MPS I and IVA model systems may uniquely illuminate the function of glycosaminoglycan-bearing proteoglycans in arterial health.

Assessing vascular characteristics of the fetal descending aorta: A feasibility study.

Research describing fetal arterial structure and function is lacking within the literature. This study's purpose was to measure intima-media thickness (IMT), compliance and distensibility of 24- to 25-week fetuses' abdominal aortas using conventional ultrasonography from 16 diabetic (DM) and 25 non-diabetic mothers (NDM). We found no significant differences in fetal abdominal aorta IMT (P = .68), diameter distensibility (P = .22), or cross-sectional distensibility (P = .23). However, both fetal abdominal aortic diameter compliance (P = .03) and cross-sectional compliance (P = .005) were greater in DM than in NDM (P = .005). This study demonstrates that it is possible and potentially useful to measure fetal abdominal aorta biometrics and biomechanical characteristics.

Reproducibility of a ramping protocol to measure cerebral vascular reactivity using functional magnetic resonance imaging.

Though individual differences in arterial carbon dioxide and oxygen levels inherently exist, the degree of their influence on cerebral vascular reactivity (CVR) is less clear. We examined the reproducibility of BOLD signal changes to an iso-oxic ramping Pet CO2 protocol. CVR changes were induced by altering Pet CO2 while holding Pet O2 constant using a computer-controlled sequential gas delivery (SGD) device. Two MRI scans, each including a linear change in Pet CO2 , were performed using a 3-Tesla (3T) scanner. This ramp sequence consisted of 1 min at 30 mmHg followed by 4 min period during where Pet CO2 was linearly increased from 30 to 50 mmHg, 1 min at 51 mmHg, and concluded with 4 min at baseline. The protocol was repeated at a separate visit with 3 days between visits (minimum). Intraclass correlation coefficients (ICC) and coefficients of variation (CV) were used to verify reproducibility. Eleven subjects (6 females; mean age 26.5 ± 5.7 years) completed the full testing protocol. Good reproducibility was observed for the within-visit ramp sequence (Visit 1: ICC = 0.82, CV = 6.5%; Visit 2: ICC = 0.74, CV = 6.4%). Similarly, ramp sequence were reproducible between visits (Scan 1: ICC = 0.74, CV = 6.5%; Scan 2: ICC = 0.66, CV = 6.1%). Establishing reproducible methodologies for measuring BOLD signal changes in response to Pet CO2 alterations using a ramp protocol will allow researchers to study CVR functionality. Finally, adding a ramping protocol to CVR studies could provide information about changes in CVR over a broad range of Pet CO2 .

Relation of secondhand smoke exposure to vascular phenotypes in children and adolescents.

BACKGROUND: Subclinical cardiovascular risks of secondhand smoke (SHS) exposure among children and adolescents remains insufficiently described. METHODS: This was a cross-sectional study of 298 children and adolescents (48.0% male, body mass index: 27.0 ± 8.9 kg/m2), including 49 self-reported cases with SHS. Arterial elasticity and stiffness (distensibility, compliance, incremental elastic modulus [IEM]) were obtained via ultrasound imaging in the abdominal aorta, brachial, and carotid arteries. A one-way analysis of variance compared differences between groups, and multiple linear regression adjusted for covariates. RESULTS: SHS was associated with lower abdominal aorta diameter distensibility (aDD) (13.4 ± 3.6% vs. 16.0 ± 5.2%, p = 0.009) and abdominal aorta cross-sectional distensibility (aCSD) (28.8 ± 8.3% vs. 35.1 ± 12.2%, p = 0.009), as well as higher abdominal aorta IEM (aIEM) (1241 ± 794 vs. 935 ± 388 mmHg, p = 0.001). After adjustment for covariates, aDD (p = 0.047), aCSD (p = 0.040), and aIEM (p = 0.017) remained significant; this significance persisted with the additional adjustment of percent body fat. Measures of brachial and carotid compliance and distensibility were not associated with SHS. CONCLUSIONS: SHS was associated with abdominal aorta stiffness; the majority of vascular measures within the brachial and carotid artery remained unaffected following adjustment for covariates, including hypertension and adiposity. SHS may predispose individuals to increased abdominal aorta stiffness, an artery previously reported to exhibit increased susceptibility to atherosclerosis.

VE/VCO2 slope in lean and overweight women and its relationship to lean leg mass.

Ventilation/carbon dioxide production (VE/VCO2slope) is used clinically to determine cardiorespiratory fitness and morbidity in heart failure (HF). Previously, we demonstrated that lower lean leg mass is associated with high VE/VCO2slope during exercise in HF. In healthy individuals, we evaluated 1) whether VE/VCO2slope differed between lean and overweight women and 2) the relationship between lean leg mass and VE/VCO2slope in overweight sedentary (OWS), overweight trained (OWTR) and lean, trained (LTR) women. METHODS: Gas exchange and ventilation were collected during a treadmill peak oxygen uptake test (VO2peak) in 40 women [26 OWS (29 ±â€¯7 yrs., mean ±â€¯SD), 7 OWTR (33 ±â€¯5 yrs) and 7 LTR (26 ±â€¯6 yrs)]. Body composition was measured by dual X-ray absorptiometry. RESULTS: VO2peak was highest in LTR (46.6 ±â€¯8 ml/kg/min) compared with OWTR (38.1 ±â€¯4.9 ml/kg/min) and OWS women (25.3 ±â€¯4.8 ml/kg/min, p < 0.05). Lean leg mass was highest in OWTR and lowest in LTR women (p < 0.05). VE/VCO2slope was similar between groups (p > 0.05). Higher lean leg mass was associated with lower VE/VCO2slope in overweight women (OWS + OWTR: r = -0.55, p < 0.001), contrasting with higher VE/VCO2slope in LTR women (r = 0.86, p < 0.001). CONCLUSIONS: These findings suggest VE/VCO2slope may not differentiate between low and high cardiorespiratory fitness in healthy individuals and muscle mass may play a role in determining the VE/VCO2slope, independent of disease.

Measurement of Central Aortic Blood Pressure in Youth: Role of Obesity and Sex.

BACKGROUND: The relationship between pediatric severe obesity (SO) and central aortic blood pressure (BP) has yet to be established. METHODS: We conducted a cross-sectional study of 348 youth (48.5% male, age 12.7 ± 0.1 years) with a wide range of body mass index (BMI) values: normal weight (NW; ≥5th and <85th BMI percentiles), overweight/obesity (OW/OB; 85th to <120% of the 95th BMI percentile), and SO (≥120% of the 95th BMI percentile). Measures of central aortic BP were obtained via applanation tonometry with SphygmoCor MM3 software. RESULTS: After adjustment for covariates, no significant sex differences were observed for radial-aortic systolic blood pressure (SBP) (P = 0.39), carotid-aortic SBP (P = 0.99), radial-aortic diastolic blood pressure (DBP) (P = 0.44), and carotid-aortic DBP (P = 0.53). Compared to youth with NW, youth with SO exhibited higher radial-aortic SBP (SO vs. NW: 102 ± 1 mm Hg vs. 90 ± 1 mm Hg, P<0.001), carotid-aortic SBP (SO vs. NW: 121 ± 1 mm Hg vs. 109 ± 1 mm Hg, P<0.001), and carotid-aortic DBP (SO vs. NW: 60 ± 1 mm Hg vs. 56 ± 1 mm Hg, P = 0.04). Compared to youth with OW/OB, youth with SO had higher radial-aortic SBP (OW/OB: 97 ± 1 mm Hg, P = 0.002) and carotid-aortic SBP (OW/OB: 114 ± 1 mm Hg, P = 0.007). After adjusting for either total-body percent fat mass or visceral adipose tissue, BMI was still a significant predictor of both radial-aortic and carotid-aortic SBP and DBP (P<0.001, all). CONCLUSIONS: In a cohort of youth with a wide range of adiposity levels, central aortic BP was elevated among individuals with SO and associated with BMI but not body fatness.

Intra- and interday reproducibility of high-flow-mediated constriction response in young adults.

BACKGROUND: Previously, we have demonstrated that high-flow-mediated constriction (H-FMC) of the brachial artery has been shown to negatively affect flow-mediated dilation (FMD). However, the reproducibility of an H-FMC response is unknown. OBJECTIVE: The aim of this study was to determine the intra- and interday reproducibility of H-FMC in young adults. METHODS: Thirty young adults (15 male, 15 female; 24 ± 3 years) were assessed for H-FMC reproducibility via high-resolution ultrasound imaging of the brachial artery during and after forearm occlusion of a normal FMD procedure. Two vascular assessments were conducted for all participants during two separate visits with a minimum of 7 days in between. H-FMC was characterized as the greatest 10-s average constriction occurring after 3-s postocclusion compared to baseline brachial artery diameter and considered present if the percent change was <-0·1%. RESULTS: Of the 120 total vascular assessments performed in this study, 98 of the assessments (80·3%) displayed an H-FMC. H-FMC diameter was not statistically different for intraday comparisons for visit 1 (P = 0·39) or visit 2 (P = 0·55) or interday comparisons between the first (P = 0·61) or second (P = 0·10) assessments. H-FMC percentage was also not statistically different for intra-day comparison for visit 1 (P = 0·94) or visit 2 (P = 0·15) or interday comparisons between the first (P = 0·63) or second (P = 0·16) assessments. CONCLUSION: These data are supportive of H-FMC being reproducible in young adults and included in future FMD studies. The impact of H-FMC on future CVD risk and development warrants evaluation.

Intra- and inter-day reproducibility of low-flow mediated constriction response in young adults.

PURPOSE: When assessing brachial endothelial function by reactive hyperaemia, stopping blood flow creates a period of low-flow-mediated constriction (L-FMC). As little is known about how this parameter influences flow-mediated vasodilation (FMD), the purpose of this study was to better understand this relationship and to determine the intra- and interday reproducibility of brachial L-FMC. METHODS: Brachial L-FMC and FMD were measured on 26 healthy, young adults (13 males, 13 females; 24·6 ± 2·7 years). Each participant had two assessments conducted on two separate visits, separated by a minimum of seven days. Brachial artery baseline diameter was imaged during rest. Continuous imaging of the artery was performed during the last 20 s of cuff-occlusion to 180 s postcuff release. An L-FMC was considered present if the relative change from pre-occlusion baseline to L-FMC artery diameter was less than -0·1%. RESULTS: Overall, there was a strong, positive correlation between increased brachial L-FMC and blunted FMD (visit 1 test 1: r = 0·758, P<0·001; visit 1 test 2: r = 0·706, P<0·001; visit 2 test 1: r = 0·836, P<0·001; visit 2 test 2: r = 0·857, P<0·001). The reproducibility of intra- and interday L-FMC diameter was intraclass correlation coefficients (ICC) = 0·627, coefficient of variation (CV) = 54·4% and ICC = 0·734, CV = 43·5%, respectively. CONCLUSION: Vasoconstriction to low-flow conditions influences the subsequent maximal dilation during reactive hyperaemia. However, L-FMC is variable as evidenced by the weak intra- and interday reproducibility of the measure. Further research should study brachial L-FMC reproducibility among varying populations and the implications L-FMC has on the interpretation of FMD results.

Determination of Bilateral Symmetry of Carotid Artery Structure and Function in Children and Adolescents.

We compared the symmetry of carotid arteries in youth with high-resolution ultrasound. Participants (n=230 (121 females),13.8 ± 2.9 years old) were assessed for: intima media thickness (cIMT), lumen diameter (cLD), incremental elastic modulus (cIEM), diameter compliance (cDC), cross-sectional compliance (cCSC), diameter distensibility (cDD), and cross-sectional distensibility (cCSD). No significant differences (P >0.05 all) were found for cIMT (0.49 ± 0.09 mm vs. 0.49 ± 0.08 mm), cIEM (1095 ± 382 mmHg vs. 1116 ± 346mmHg), cDC (0.01 ± 0.0 mm/mmHg vs. 0.01 ± 0.0 mm/mmHg), cCSC (0.01 ± 0.001/mmHg vs. 0.01 ± 0.001/mmHg), cDD (14.0 ± 3.16% vs. 13.7 ± 3.18%), and cCSD (30.1 ± 7.37% vs. 29.4 ± 7.36%). Significant differences were found for cLD (6.06 ± 0.62 mm vs. 6.33 ± 0.64 mm, P <0.001). These data suggest that these values may be used interchangeably if one side is inaccessible.

Reproducibility of blood oxygen level-dependent signal changes with end-tidal carbon dioxide alterations.

Hypercapnia has been utilized as a stimulus to elicit changes in cerebral blood flow (CBF). However, in many instances it has been delivered in a non-controlled method that is often difficult to reproduce. The purpose of this study was to examine the within- and between-visit reproducibility of blood oxygen level-dependent (BOLD) signal changes to an iso-oxic square wave alteration in end-tidal carbon dioxide partial pressure (Pet CO2 ). Two 3-Tesla (3T) MRI scans were performed on the same visit, with two square wave alterations administered per scan. The protocol was repeated on a separate visit with minimum of 3 days between scanning sessions. Pet CO2 was altered to stimulate changes in cerebral vascular reactivity (CVR), while Pet O2 was held constant. Eleven subjects (six females; mean age 26·5 ± 5·7 years) completed the full testing protocol. Excellent within-visit square wave reproducibility (ICC > 0·75) was observed. Similarly, square waves were reproducible between scanning sessions (ICC > 0·7). This study demonstrates BOLD signal changes in response to alterations in Pet CO2 are reproducible both within- and between-visit MRI scans.