ABSTRACT
Introduction: The aim of this study was to compare ultrasound echo intensity (EI) with high‐resolution T1‐weighted MRI and to establish calibration equations to estimate percent ...intramuscular fat from EI. Methods: Thirty‐one participants underwent both ultrasound and MRI testing of 4 muscles: rectus femoris (RF); biceps femoris (BF); tibialis anterior (TA); and medial gastrocnemius (MG). Results: Strong correlations were found between MRI percent fat and muscle EI after correcting for subcutaneous fat thickness (r = 0.91 in RF, r = 0.80 in BF, r = 0.80 in TA, r = 0.76 in MG). Three types of calibration equations were established. Conclusions: Muscle ultrasound is a practical and reproducible method that can be used as an imaging technique for examination of percent intramuscular fat. Future ultrasound studies are needed to establish equations for other muscle groups to enhance its use in both research and clinical settings. Muscle Nerve 52: 963–971, 2015
Individuals differ in the response to regular exercise. Whether there are people who experience adverse changes in cardiovascular and diabetes risk factors has never been addressed.
An adverse ...response is defined as an exercise-induced change that worsens a risk factor beyond measurement error and expected day-to-day variation. Sixty subjects were measured three times over a period of three weeks, and variation in resting systolic blood pressure (SBP) and in fasting plasma HDL-cholesterol (HDL-C), triglycerides (TG), and insulin (FI) was quantified. The technical error (TE) defined as the within-subject standard deviation derived from these measurements was computed. An adverse response for a given risk factor was defined as a change that was at least two TEs away from no change but in an adverse direction. Thus an adverse response was recorded if an increase reached 10 mm Hg or more for SBP, 0.42 mmol/L or more for TG, or 24 pmol/L or more for FI or if a decrease reached 0.12 mmol/L or more for HDL-C. Completers from six exercise studies were used in the present analysis: Whites (N = 473) and Blacks (N = 250) from the HERITAGE Family Study; Whites and Blacks from DREW (N = 326), from INFLAME (N = 70), and from STRRIDE (N = 303); and Whites from a University of Maryland cohort (N = 160) and from a University of Jyvaskyla study (N = 105), for a total of 1,687 men and women. Using the above definitions, 126 subjects (8.4%) had an adverse change in FI. Numbers of adverse responders reached 12.2% for SBP, 10.4% for TG, and 13.3% for HDL-C. About 7% of participants experienced adverse responses in two or more risk factors.
Adverse responses to regular exercise in cardiovascular and diabetes risk factors occur. Identifying the predictors of such unwarranted responses and how to prevent them will provide the foundation for personalized exercise prescription.
Perivascular adipose tissue (PVAT) is implicated as a source of proatherogenic cytokines. Phenotypic differences in local PVAT depots may contribute to differences in disease susceptibility among ...arteries and even regions within an artery. It has been proposed that PVAT around the abdominal and thoracic aorta shares characteristics of white and brown adipose tissue (BAT), respectively; however, a detailed comparison of the phenotype of these PVAT depots has not been performed. Using young and older adult rats, we compared the phenotype of PVATs surrounding the abdominal and thoracic aorta to each other and also to epididymal white and subscapular BAT. Compared with young rats, older rats exhibited greater percent body fat (34.5 ± 3.1 vs. 10.4 ± 0.9%), total cholesterol (112.2 ± 7.5 vs. 58.7 ± 6.3 mg/dl), HOMA-insulin resistance (1.7 ± 0.1 vs. 0.9 ± 0.1 a.u.), as well as reduced ACh-induced relaxation of the aorta (maximal relaxation: 54 ± 10 vs. 77 ± 6%) (all P < 0.05). Expression of inflammatory genes and markers of immune cell infiltration were greater in abdominal PVAT than in thoracic PVAT, and overall, abdominal and thoracic PVATs resembled the phenotype of white adipose tissue (WAT) and BAT, respectively. Histology and electron microscopy indicated structural similarity between visceral WAT and abdominal PVAT and between BAT and thoracic PVAT. Our data provide evidence that abdominal PVAT is more inflamed than thoracic PVAT, a difference that was by and large independent of sedentary aging. Phenotypic differences in PVAT between regions of the aorta may be relevant in light of the evidence in large animals and humans that the abdominal aorta is more vulnerable to atherosclerosis than the thoracic aorta.
Physical inactivity promotes the development of cardiovascular diseases. However, few data exist examining the vascular consequences of short-term reductions in daily physical activity. Thus we ...tested the hypothesis that popliteal and brachial artery flow-mediated dilation (FMD) would be reduced and concentrations of endothelial microparticles (EMPs) would be elevated following reduced daily physical activity. To examine this, popliteal and brachial artery FMD and plasma levels of EMPs suggestive of apoptotic and activated endothelial cells (CD31(+)/CD42b(-) and CD62E(+) EMPs, respectively) were measured at baseline and during days 1, 3, and 5 of reduced daily physical activity in 11 recreationally active men (25 ± 2 yr). Subjects were instructed to reduce daily physical activity by taking <5,000 steps/day and refraining from planned exercise. Popliteal artery FMD decreased with reduced activity (baseline: 4.7 ± 0.98%, reduced activity day 5: 1.72 ± 0.68%, P < 0.05), whereas brachial artery FMD was unchanged. In contrast, baseline (pre-FMD) popliteal artery diameter did not change, whereas brachial artery diameter decreased (baseline: 4.35 ± 0.12, reduced activity day 5: 4.12 ± 0.11 P < 0.05) following 5 days of reduced daily physical activity. CD31(+)/CD42b(-) EMPs were significantly elevated with reduced activity (baseline: 17.6 ± 9.4, reduced activity day 5: 104.1 ± 43.1 per μl plasma, P < 0.05), whereas CD62E(+) EMPs were unaltered. Collectively, our results provide evidence for the early and robust deleterious impact of reduced daily activity on vascular function and highlight the vulnerability of the vasculature to a sedentary lifestyle.
There is strong and consistent evidence from in vitro studies that disturbed blood flow produces a proatherogenic vascular endothelial phenotype. However, data from human studies are lacking. To ...address this, a 220 mm Hg occlusion cuff was placed on the distal forearm of 10 young, healthy men to induce a localized region of disturbed blood flow in the proximal vasculature for 20 minutes. We hypothesized that disturbed blood flow would induce endothelial activation and apoptosis as indicated by increases in local concentrations of CD62E(+) and CD31(+)/CD42b(-) endothelial microparticles, respectively. Distal cuff occlusion induced reductions in mean blood flow, mean shear, and antegrade shear, and increases in retrograde flow, retrograde shear, and oscillatory shear stress, confirming that our protocol produced a disturbed blood flow stimulus in the experimental arm. Relative to baseline (0 minutes), CD62E(+) endothelial microparticles increased by ≈3-fold at 10 minutes and ≈4-fold at 20 minutes in the experimental arm (P<0.05). CD31(+)/CD42b(-) endothelial microparticles were elevated by ≈9-fold at the 20 minutes time point (P<0.05). There were no changes in the concentrations of either endothelial microparticle population throughout the experiment in the contralateral arm, exposed to normal resting blood flow (no cuffs). These findings indicate that disturbed blood flow acutely induces endothelial activation and apoptosis in humans, as reflected by release of microparticles from activated (CD62E(+)) and apoptotic (CD31(+)/CD42b(-)) endothelial cells. These data provide the first in vivo experimental evidence of disturbed blood flow-induced endothelial injury in humans.
Patients with obesity and diabetes mellitus exhibit a high prevalence of cardiac diastolic dysfunction (DD), an independent predictor of cardiovascular events for which no evidence-based treatment ...exists. In light of renin-angiotensin-aldosterone system activation in obesity and the cardioprotective action of mineralocorticoid receptor (MR) antagonists in systolic heart failure, we examined the hypothesis that MR blockade with a blood pressure-independent low-dose spironolactone (LSp) would treat obesity-associated DD in the Zucker obese (ZO) rat. Treatment of ZO rats exhibiting established DD with LSp normalized cardiac diastolic function, assessed by echocardiography. This was associated with reduced cardiac fibrosis, but not reduced hypertrophy, and restoration of endothelium-dependent vasodilation of isolated coronary arterioles via a nitric oxide-independent mechanism. Further mechanistic studies revealed that LSp reduced cardiac oxidative stress and improved endothelial insulin signaling, with no change in arteriolar stiffness. Infusion of Sprague-Dawley rats with the MR agonist aldosterone reproduced the DD noted in ZO rats. In addition, improved cardiac function in ZO-LSp rats was associated with attenuated systemic and adipose inflammation and an anti-inflammatory shift in cardiac immune cell mRNAs. Specifically, LSp increased cardiac markers of alternatively activated macrophages and regulatory T cells. ZO-LSp rats had unchanged blood pressure, serum potassium, systemic insulin sensitivity, or obesity-associated kidney injury, assessed by proteinuria. Taken together, these data demonstrate that MR antagonism effectively treats established obesity-related DD via blood pressure-independent mechanisms. These findings help identify a particular population with DD that might benefit from MR antagonist therapy, specifically patients with obesity and insulin resistance.
Background
High‐intensity functional training (HIFT) can play a major role in physiological adaptations to prevent cardiometabolic disease. A majority of HIFT interventions incorporate a CrossFit ...(CF) training methodology, in which the goal is to increase work capacity over time while using mono‐structural, body weight, and weightlifting movements.
Methods
We measured aerobic capacity, metabolic response during high‐intensity interval exercise (HIIE), resting mitochondrial oxidative capacity, and resting large vessel function and microvascular reactivity in adults who have participated in a CF exercise for greater than one year vs. a sedentary group completing <2 h·wk‐1 of structure exercise for at least one year (SED).
Results
21 healthy, non‐smoking, participants were recruited (CF n = 13 vs. SED n = 8). CF participants had 40.4% greater absolute and 33.0% relative VO2 peak (P < 0.001) and lower body composition (CF = 18.6 (3.8) vs. SED = 30.3 (8.4); P < 0.001). CF participants had lower ratings of perceived exertion (P = 0.022) with higher respiratory responses (P < 0.05) and a lower heart rate response during HIIE (P = 0.024). CF participants had higher fat and carbohydrate oxidation when expressed as absolute and body weight relative values (P < 0.013), but not when expressed relative to lean mass (P > 0.200), indicating that skeletal muscle mass is a primary driver in substrate oxidation. CF participants had greater mitochondrial oxidative capacity (CF n = 12; P = 0.014). There were no differences in large artery function, but CF participants had greater baseline arterial diameter (CF n = 12; P = 0.004) and faster reperfusion following arterial occlusion (CF n = 12; P < 0.05), suggesting some influence of exercise habits on microvascular function.
Conclusion
Overall, these data support the effectiveness of HIFT programs, like CF exercise, to improve fitness and weight status and metabolic, mitochondrial, and vascular function.
Pecans are rich in bioactive compounds known to reduce oxidative stress and provide glucoregulatory benefits. Few studies assessing the effect of a pecan-enriched diet on such health outcomes suggest ...potential improvements to cardiometabolic health; however, this has not been studied in an older adult population. Thus, we aimed to examine the effect of daily pecan consumption for 4-weeks on fasting and postmeal antioxidant status, oxidative stress, and markers of glycemia in healthy aging adults. In this randomized, parallel, controlled trial, 41 healthy adults (50-75 years) either consumed 68 g of pecans/day (pecan;
= 21) or avoided all nuts (control;
= 20). At pre- (V1) and postintervention visits (V2), blood samples were obtained at fasting, and 30, 60, and 120 min following a high saturated fat meal to assess changes in malondialdehyde, which is a measure of lipid peroxidation, total antioxidant capacity (TAC), glucose, and insulin. Across the intervention, there were no differences in fasting or postprandial TAC, glucose, or insulin for pecan versus control. There was a trend for a difference in fasting lipid peroxidation from V1 to V2 by treatment (
= .06) driven by a slight reduction for pecan versus control (Δpecan: -2.0 ± 1.1 vs. Δcontrol: +0.6 ± 0.8
M). In addition, postprandial lipid peroxidation was suppressed at V2 for pecan, and this was different from control (pecan areas under the curve (AUC): 10.6 ± 1.3
M/h to 9.1 ± 1.2
M/h vs. control AUC: 8.9 ± 1.3
M/h to 9.2 ± 1.1
M/h;
= .03). These findings suggest that a 1 month, pecan-enriched diet is protective against postmeal oxidative stress. Longer interventions or a diabetic population may be needed to observe glucoregulatory benefits.
NCT04385537.
Purpose: We compared aerobic capacity (
), mitochondrial capacity (
), anaerobic power, strength, and muscle endurance in healthy, active men from strength (STR), endurance (END) and high-intensity ...functional training (HIFT) backgrounds.
Methods:
Twenty-four men (n = 8/group) completed a cycle ergometer test to determine
, followed by a 3-min all-out test to determine peak (PP) and end power (EP), and to estimate anaerobic work done above EP (WEP) and aerobic work capacity. Strength was determined by knee extensor maximal voluntary contraction at various flexion angles. The endurance index (EI) of the vastus lateralis (VL) was assessed by measuring muscle contraction acceleration during electrical twitch mechanomyography.
of the VL was assessed using near-infrared spectroscopy to estimate muscle oxygen consumption during transient femoral artery occlusions. Results:
was significantly different among groups (p < .05). PP was significantly higher in HIFT and STR versus END (p < .05). EP was significantly higher in HIFT and END compared to STR (p < .05). WEP was significantly higher in STR compared to END (p < .05), whereas total work done was significantly higher in HIFT and END compared to STR (p < .05).
and EI were comparable between HIFT and END but significantly lower in STR versus END (p < .05). Torque production was significantly lower in END compared to STR and HIFT at all flexion angles (p < .05), with no difference between STR and HIFT.
Conclusion:
HIFT participants can exert similar power outputs and absolute strength compared to strength focused participants but exhibit fatigue resistance and mitochondrial capacity comparable to those who train for endurance.
PDF
