Treadmill walking economy is not affected by body fat and body mass index in adults.

To determine whether body fat and body mass index (BMI) affect the energy cost of walking (Cw; J/kg/m), ventilation, and gas exchange data from 205 adults (115 females; percent body fat range = 3.0%-52.8%; BMI range = 17.5-43.2 kg/m2) were obtained at rest and during treadmill walking at 1.34 m/s to calculate gross and net Cw. Linear regression was used to assess relationships between body composition indices, Cw, and standing metabolic rate (SMR). Unpaired t-tests were used to assess differences between sex, and one-way ANOVA was used to assess differences by BMI categories: normal weight, <25.0 kg/m2; overweight, 25.0-29.9 km/m2; and obese, ≥30 kg/m2. Net Cw was not related to body fat percent, fat mass, or BMI (all R2 ≤ 0.011). Furthermore, mean net Cw was similar by sex (male: 2.19 ± 0.30 J/kg/m; female: 2.24 ± 0.37 J/kg/m, p = 0.35) and across BMI categories (normal weight: 2.23 ± 0.36 J/kg/m; overweight: 2.18 ± 0.33 J/kg/m; obese: 2.26 ± 0.31, p = 0.54). Gross Cw and SMR were inversely associated with percent body fat, fat mass, and BMI (all R2 between 0.033 and 0.270; all p ≤ 0.008). In conclusion, Net Cw is not influenced by body fat percentage, total body fat, and BMI and does not differ by sex.

Dietary Intake and Quality among Stroke Survivors: NHANES 1999-2018.

BACKGROUND: Nutrition is an important modifiable risk factor for prevention and treatment of stroke. However, examination of nutrient intake and diet quality in stroke survivors is limited. OBJECTIVES: The aim of the study was to estimate usual nutrient intake and diet quality in US adults with and without a history of self-reported stroke. METHODS: Using US National Health and Nutrition Examination Survey (NHANES) 1999-2018, we analyzed demographics, health history, and dietary intake data in 1626 individuals with a history of stroke matched for age, gender, and survey cycle to respective controls (n=1621) with no history of stroke. A minimum of one 24-h dietary recall was used to assess dietary intake. Diet quality was determined using Healthy Eating Index 2015 (HEI-2015) scores. Adult food security was assessed based on responses to the US Department of Agriculture Household Food Security Survey Module. Physical and mental limitations were assessed from responses to the NHANES Physical Functioning Questionnaire. Estimates were reported as mean (standard error). RESULTS: In comparison to controls, stroke survivors were more likely to be food insecure, experience poverty, and report physical and mental limitations (P < .001, all comparisons). Stroke survivors were more likely to report excessive (% > acceptable macronutrient distribution range) intake for total fat (50.9 [2.7]% vs. 40.4 [2.2]%, P < .001) and inadequate intake (% < estimated average requirement) for calcium (54.6 [1.8]% vs. 43.5 [2.4]%, P = .001) and magnesium (66 [1.8] vs. 53.6 [1.8]%, P < .001). In addition, stroke survivors reported lower HEI-2015 total scores than controls (49.8 vs. 51.9, P < .001). Finally, HEI-2015 total scores were lower in stroke survivors who were food insecure and those with a lower income-to-poverty ratio (< 185%) (P = .001). CONCLUSIONS: Dietary intake in stroke survivors was nutritionally poor, with suboptimal nutrient intake and lower overall diet quality compared with age- and gender-matched controls. Furthermore, poverty and food insecurity were more prevalent in stroke survivors and associated with worse diet quality.

Serum Cholesterol Differences Between Statin Users Who Take Dietary Supplements and Those Who Do Not: NHANES 2013-2018.

Background: Cardiovascular disease (CVD) is the leading cause of mortality in the United States and statins are the most commonly prescribed medication. It is important to understand the potential impact supplements may have when taken in combination with statins on serum lipid outcomes. Objectives: To evaluate the differences in the concentrations of cholesterol, triacylglycerol (TAG), and HbA1c between adults who use statins alone and those who combine statins and dietary supplements. Methods: A cross-sectional analysis using data from US adults aged ≥20 years who participated in the NHANES (2013-2018). The serum concentrations of lipids and the HbA1c levels were compared using independent sample t-tests. All analyses were adjusted for the complex survey design and used appropriate sample weights. Results: Of 16,327 participants included in this analysis, 13% reported the use of statins alone, and 8.8% used statins and dietary supplements. Statin users who used dietary supplements tended to be women (50.5%), aged 65.8 ± 0.4 years, and were more likely to be White (77.4%). Participants who used statins in combination with dietary supplements were less likely to have higher levels of total cholesterol (5.1% ± 1.4% vs. 15.6% ± 2.7%, P < 0.001), HbA1c (6.0% ± 0.1% vs. 6.3% ± 0.1%, P < 0.05), and HDL cholesterol (50 ± 1.3 vs. 47 ± 0.8 mg/dL, P < 0.05) than those who used statins alone. No significant differences were identified between the two groups for LDL cholesterol and TAG concentrations. Conclusions: Statin users who coingested dietary supplements were less likely to have high levels of total cholesterol and HbA1c and greater HDL levels than statin users who did not take dietary supplements. Dietary intake, lifestyle choices, and other confounders may have influenced the observed outcome differences for those who took dietary supplements with statins and those who did not.

Resistant starch improves cardiometabolic disease outcomes: A narrative review of randomized trials.

Healthy dietary patterns with adequate fiber improve cardiometabolic (CM) outcomes and attenuate disease progression. Resistant starch (RS) is a fermentable fiber that affects CM outcomes; however, studies are heterogeneous and inconsistent. Thus, the purpose of this narrative review is to assess the impact of RS intake by type and amount on CM outcomes while considering subject characteristics and trial duration. Randomized crossover or parallel studies (n = 31) were selected and compared according to acute (1 day; n = 12), medium (>1-30 days; n = 8), or long (>30 days; n = 11) duration. Most acute trials in healthy adults showed improvements in postprandial glycemic outcomes irrespective of RS type or amount. However, a more pronounced reduction occurred when test meals did not match for available carbohydrate. Daily RS intake had a minimal effect on CM outcomes in medium duration trials, but insulin resistant adults had better glycemic control at 4 weeks. Several longer duration trials (8-12 weeks) showed favorable CM outcomes with daily RS intake in adults with type 2 diabetes (T2D), but not in those at risk for T2D. Furthermore, some studies reported improved lipids, inflammatory biomarkers, and heart rate. Future studies should consider matching for available carbohydrates between the RS and control groups to understand the gut microbiome's role. Furthermore, energy and fiber should be considered. Overall, the acute intake of RS improves glycemic outcomes, and consuming RS at for least 4 and up to 8 to 12 weeks in adults with prediabetes and T2D, respectively, appears to improve CM outcomes.

Usual dietary fibre intake according to diabetes status in USA adults - NHANES 2013-2018.

It is unknown if fibre intake differs across diabetes status in USA adults and is associated with glycaemic outcomes. This cross-sectional analysis utilised National Health and Nutrition Examination Survey cycles 2013-2018 data to estimate usual total dietary fibre intake in USA adults and across diabetes status (no diabetes, prediabetes and type II diabetes (T2D)). Associations among dietary fibre intake and glycaemic outcomes were also reported across groups. Adults (≥ 19 years) with at least one dietary recall were included. Diabetes status was determined from self-report data and measured HbA1c. Independent samples t tests were used to compare mean (se) intake across sub-populations. 14 640 adults (51·3 % female) with 26·4 % and 17·4 % classified as having prediabetes and T2D, respectively. Adults with T2D reported greater mean (se) dietary fibre intake compared with no T2D for females (9·5 (0·13) v. 8·7 (0·11) g/1000 kcal/d and males (8·5 (0·12) v. 7·7 (0·11) g/1000 kcal/d; P < 0·01)). However, only 4·2 (0·50)% and 8·1 (0·90)% of males and females with T2D, respectively, met the adequate intake for fibre. Fibre intake was associated with lower insulin (ß = -0·80, P < 0·01), serum glucose (ß = -1·35, P < 0·01) and Homeostatic Model Assessment for Insulin Resistance (ß = -0·22, P < 0·01) in adults without diabetes, and no relationships in adults with prediabetes or T2D were found. Although dietary fibre intake was highest among adults with T2D, intake was suboptimal across all groups. In adults without diabetes, dietary fibre intake was associated with improved glycaemic outcomes and insulin resistance; however, these associations were attenuated by anthropometric and lifestyle covariates.

Exercise Leg Blood Flow Is Preserved in Long-term Breast Cancer Survivors Previously Treated With Anthracycline Chemotherapy.

PURPOSE: The objective of this investigation was to compare the acute hemodynamic responses during single-leg knee extension (SLKE) exercise between female breast cancer (BC) survivors previously treated with anthracycline chemotherapy and age- and sex-matched control (CON) subjects. METHODS: Fourteen BC survivors (age: 61 ± 7 yr; time post-anthracycline therapy: 12 ± 6 yr) and nine CON subjects (age: 59 ± 7 yr) performed SLKE exercise at 25%, 50%, and 75% of peak power output during which heart rate, blood pressure (BP), leg blood flow (Doppler ultrasonography), and vascular conductance (leg blood flow/mean BP) were measured. Quadriceps mass was estimated from thigh volume and skinfold measures. RESULTS: Breast cancer survivors had lower quadriceps mass compared with CON subjects (1803 ± 607 vs 2601 ± 1102 g, P = .04). No difference was found between groups for maximal SLKE power output (28 ± 11 vs 34 ± 17 W, P = .35), heart rate (109 ± 14 vs 103 ± 13 bpm, P = .36), or mean arterial BP (122 ± 18 vs 119 ± 26 mm Hg, P = .33). Rest and submaximal exercise mean arterial BP, leg blood flow (indexed to quadriceps muscle mass), and leg vascular conductance were not significantly different between BC survivors and CON subjects. CONCLUSION: Leg blood flow during submaximal SLKE exercise is preserved in long-term BC survivors previously treated with anthracycline chemotherapy.

Cognition and brain oxygen metabolism improves after bariatric surgery-induced weight loss: A pilot study.

Objective: The primary objectives of this pilot study were to assess cognition and cerebral metabolic rate of oxygen (CMRO2) consumption in people with severe obesity before (baseline), and again, 2- and 14-weeks after sleeve gastrectomy bariatric surgery. Methods: Six people with severe/class 3 obesity (52 ± 10 years, five females, body mass index (BMI) = 41.9 ± 3.9 kg/m2), and 10 normal weight sex- and age-matched healthy controls (HC) (48 ± 6 years, eight females, 22.8 ± 1.9 kg/m2). Global CMRO2 was measured non-invasively using MRI and cognition using the Integneuro testing battery. Results: Following a sleeve gastrectomy induced weight loss of 6.4 ± 2.5 kg (% total-body-weight-lost = 5.4) over two-weeks, cognition total scores improved by 0.8 ± 0.5 T-scores (p=0.03, 15.8% improvement from baseline). Weight loss over 14-weeks post-surgery was 15.4 ± 3.6 kg (% total-body-weight-lost = 13.0%) and cognition improved by 1.1 ± 0.4 (p=0.003, 20.6% improvement from baseline). At 14-weeks, cognition was 6.4 ± 0.7, comparable to 6.0 ± 0.6 observed in the HC group. Baseline CMRO2 was significantly higher compared to the HC (230.4 ± 32.9 vs. 177.9 ± 33.9 µmol O2/100 g/min, p=0.02). Compared to baseline, CMRO2 was 234.3 ± 16.2 µmol O2/100 g/min at 2-weeks after surgery (p=0.8, 1.7% higher) and 217.3 ± 50.4 at 14-weeks (p=0.5, 5.7% lower) after surgery. 14-weeks following surgery, CMRO2 was similar to HC (p=0.17). Conclusion: Sleeve gastrectomy induced weight loss was associated with an increase in cognition and a decrease in CMRO2 observed 14-weeks after surgery. The association between weight loss, improved cognition and CMRO2 decrease should be evaluated in larger future studies.

Exercise for Primary and Secondary Prevention of Cardiovascular Disease: JACC Focus Seminar 1/4.

Regular exercise that meets or exceeds the current physical activity guidelines is associated with a reduced risk of cardiovascular disease (CVD) and mortality. Therefore, exercise training plays an important role in primary and secondary prevention of CVD. In this part 1 of a 4-part focus seminar series, we highlight the mechanisms and physiological adaptations responsible for the cardioprotective effects of exercise. This includes an increase in cardiorespiratory fitness secondary to cardiac, vascular, and skeletal muscle adaptations and an improvement in traditional and nontraditional CVD risk factors by exercise training. This extends to the role of exercise and its prescription in patients with CVDs (eg, coronary artery disease, chronic heart failure, peripheral artery disease, or atrial fibrillation) with special focus on the optimal mode, dosage, duration, and intensity of exercise to reduce CVD risk and improve clinical outcomes in these patients.

College Campus Food Pantry Program Evaluation: What Barriers Do Students Face to Access On-Campus Food Pantries?

The purpose of this study was to explore barriers Texas Woman's University (TWU) students face in accessing on-campus food pantries. This cross-sectional, survey-based study was conducted in Fall 2021. Students' use of the food pantries and barriers to utilization, including qualitative questions, were evaluated using descriptive statistics and thematic analyses. Students (n = 529) completed the survey. Despite a high prevalence of food insecurity (49.2%), most students reported never using the pantries (89.8%). Almost half of the students were unaware that these pantries existed on campus (47.8%). More than one in four students believed there were barriers to accessing the pantries, with time tissues, lack of transportation, limited food pantry hours of operation, and social stigma most commonly cited as major barriers to access. Food insecurity remains an urgent problem at TWU since the prevalence has remained high since 2019 despite the institutions' efforts to reduce it. One of those resources has not been utilized as expected, which might impede improvements in food security among students. TWU on-campus food pantries can use these findings to address major barriers by offering after-hours access through the libraries or campus police, partnering with public transportation, and normalizing accessing food assistance.

Cardiac mechanisms for low aerobic power in anthracycline treated, older, long-term breast cancer survivors.

Breast cancer survivors have reduced peak aerobic capacity (VO2peak) which may be related to latent or lingering chemotherapy induced cardiac damage. Nine, older (67 ± 3 years), long-term survivors (9.8 years) of anthracycline based chemotherapy and age- and sex-matched healthy controls were recruited and tested to determine whether: i) VO2peak remains reduced in long-term survivorship; and ii) reductions in VO2peak are due to cardiac dysfunction. VO2peak was significantly reduced in breast cancer survivors relative to healthy controls (15.9 ± 2.0 vs 19.9 ± 3.1 ml/kg/min, p = 0.006), however the heart rate and stroke volume responses to exercise were normal (heart rate reserve; 88 ± 9 vs 85 ± 10 bpm, p = 0.62: stroke volume reserve; 13 ± 6 vs 13 ± 9 ml,p = 0.94). These findings indicate low-normal ventricular size in long-term breast cancer survivors, but normal reserve function.

Postexercise Hypotension Is Delayed in Men With Obesity and Hypertension.

Background: Postexercise hypotension (PEH) can play a major role in the daily blood pressure management among individuals with hypertension. However, there are limited data on PEH in persons with obesity and hypertension, and no PEH data in this population beyond 90 min postexercise. Purpose: The purpose of this study was to determine if PEH could be elicited in men with obesity and hypertension during a 4-h postexercise measurement period. Methods: Seven men [age = 28 ± 4 years; body mass index = 34.6 ± 4.8 kg/m2; brachial systolic blood pressure (SBP): 138 ± 4 mmHg; brachial diastolic BP (DBP): 80 ± 5 mmHg; central SBP: 125 ± 4 mmHg; central DBP: 81 ± 8 mmHg] performed two exercise sessions on a cycle ergometer, each on a separate day, for 45 min at ∼65% VO2max. One exercise session was performed at a cadence of 45 RPM and one at 90 RPM. Blood pressure was monitored with a SunTech Oscar2 ambulatory blood pressure monitor for 4 h after both exercise sessions, and during a time-matched control condition. Results: Both brachial and central SBP were not changed during the first h postexercise but were reduced by ∼5-11 mmHg between 2 and 4 h postexercise (p < 0.05) after both exercise sessions. Brachial and central DBP were elevated by ∼5 mmHg at 1 h postexercise (p < 0.05) but were ∼2-3 mmHg lower compared to control at 4 h postexercise, and ∼2-4 mmHg lower at 3 h postexercise compared to baseline. Mean arterial pressure (MAP) was elevated compared to control at 1 h postexercise after both exercise sessions, but was ∼2-3 mmHg lower compared to control at 2, 3, and 4 h postexercise, and ∼4-7 mmHg lower at 3 h postexercise compared to baseline. Conclusion: Despite the small sample size and preliminary nature of our results, we conclude that PEH is delayed in men with obesity and hypertension, but the magnitude and duration of PEH up to 4 h postexercise is similar to that reported in the literature for men without obesity and hypertension. The PEH is most pronounced for brachial and central SBP and MAP. The virtually identical pattern of PEH after both exercise trials indicates that the delayed PEH is a reproducible finding in men with obesity and hypertension.

Effects of indulgent food snacking, with and without exercise training, on body weight, fat mass, and cardiometabolic risk markers in overweight and obese men.

We hypothesized that exercise training would prevent gains in body weight and body fat, and worsening of cardiometabolic risk markers, during a 4-week period of indulgent food snacking in overweight/obese men. Twenty-eight physically inactive men (ages 19-47 yr) with body mass index (BMI) ≥25 kg/m2 consumed 48 donuts (2/day, 6 days/week; ~14,500 kcal total) for 4 weeks while maintaining habitual diet. Men were randomly assigned to control (n = 9), moderate-intensity continuous training (MICT; n = 9), or high-intensity interval training (HIIT; n = 10). Exercise training occurred 4 days/week, ~250 kcal/session. Controls did not increase body weight, body fat, or visceral abdominal fat. This was partially explained by a decrease in self-reported habitual energy (-239 kcal/day, p = 0.05) and carbohydrate (-47 g/day; p = 0.02) intake. Large inter-individual variability in changes in body weight, fat, and fat-free mass was evident in all groups. Fasting blood pressure, and blood concentrations of glucose, insulin, and lipids were unchanged in all groups. Glucose incremental area under the curve during an oral glucose tolerance test was reduced by 25.6% in control (p = 0.001) and 32.8% in MICT (p = 0.01) groups. Flow-mediated dilation (FMD) was not changed in any group. VO2max increased (p ≤ 0.001) in MICT (9.2%) and HIIT (12.1%) groups. We conclude that in physically inactive men with BMI ≥25 kg/m2 , consuming ~14,500 kcal as donuts over 4 weeks did not adversely affect body weight and body fat, or several markers of cardiometabolic risk. Consumption of the donuts may have prevented the expected improvement in FMD with HIIT.

Influence of COVID-19 Pandemic Restrictions on College Students' Dietary Quality and Experience of the Food Environment.

The COVID-19 pandemic restrictions sent college students online and off campus, potentially reducing access to healthy food. The objective of this cross-sectional, internet-based study was to use qualitative and quantitative survey methods to evaluate whether COVID-19 pandemic restrictions in Texas, USA affected college students' ability to buy food, how/what they shopped for, how they prepared food, what they ate, how they felt about eating, and overall dietary quality (assessed using Healthy Eating Index [HEI] scores). Survey responses from 502 students (87.5% female; 59.6% nonwhite, mean age 27.5 ± 0.4 years, >50% graduate students) were analyzed. The qualitative analysis of open-ended questions revealed 110 codes, 17 subthemes, and six themes. Almost all students experienced changes in at least one area, the most common being changes in shopping habits. Participants with low or very low food security had lower HEI scores compared to food secure students (p = 0.047). Black students were more likely to report changes in their ability to buy food (p = 0.035). The COVID-19 restrictions varied in their impact on students' ability to access sufficient healthy food, with some students severely affected. Thus, universities should establish procedures for responding to emergencies, including identifying at-risk students and mobilizing emergency funds and/or food assistance.

Prevalence and Social Determinants of Food Insecurity among College Students during the COVID-19 Pandemic.

The coronavirus disease (COVID-19) pandemic has increased unemployment and food insecurity in the United States (US). Prior to the pandemic, college students exhibited higher rates of food insecurity than nonstudent households. The objectives of this study were to assess the prevalence and determinants of food insecurity among college students during the COVID-19 pandemic. We administered an online survey to 651 students on three diverse campuses at a state-funded university in Texas, US, in May 2020. Food security was assessed using a multistep approach that included the 2-item Food Sufficiency Screener and 6-Item USDA Food Security Survey Module (FSSM). Overall, 34.5% of respondents were classified as food insecure within the last 30 days. The strongest predictors of food insecurity were change in current living arrangement (OR = 2.70, 95% CI: 2.47, 2.95), being furloughed (OR = 3.22, 95% CI: 2.86, 3.64), laid off (OR = 4.07, 95% CI: 3.55, 4.66), or losing part-time work (OR = 5.73, 95% CI: 5.09, 6.46) due to the COVID-19 pandemic. These findings highlight the high prevalence of food insecurity among college students during the COVID-19 pandemic, with students who experienced housing insecurity and/or loss of income due to the pandemic being impacted the most.

Exercise Training Effects on the Relationship of Physical Function and Health-Related Quality of Life Among Older Heart Failure Patients With Preserved Ejection Fraction.

PURPOSE: Although exercise training (ET) has been shown to improve both physical function and health-related quality of life (HRQOL) in older patients with heart failure and preserved ejection fraction (HFpEF), the relationship between changes in these important patient-centered outcome measures has not been adequately investigated. METHODS: Patients (n = 116) with HFpEF (from 2 previous randomized controlled trials) were assigned to either 16 wk of endurance ET or attention control (CON). The ET in both trials consisted of ≤ 60 min of moderate-intensity endurance ET 3 time/wk. Peak exercise oxygen uptake (V˙o2peak) and other exercise capacity measures were obtained from a cardiopulmonary exercise test on an electronically braked cycle ergometer and 6-min walk test (6MWT). HRQOL was assessed using the Minnesota Living with Heart Failure (MLHF) Questionnaire and the 36-item Short Form Health Survey (SF-36). RESULTS: Compared with CON, the ET group demonstrated significant improvement in measures of physical function (V˙o2peak and 6MWT) at 16 wk of follow-up. There were no significant differences observed between the groups for MLHF scores, but the ET group showed significant improvements on the SF-36. There were no significant correlations between change in any of the physical function and HRQOL measures in the ET group. CONCLUSIONS: While endurance ET improved both physical function and some domains of HRQOL, the lack of significant correlations between changes in these measures suggests the effects of ET on physical function and HRQOL are largely independent of one another. Since these measures assess important and unique patient-centered outcomes in HFpEF patients, both physical function and HRQOL should be assessed in exercise-based programs and clinical trials.

Impact of bariatric surgery on cerebral vascular reactivity and cognitive function: a non-randomized pilot study.

BACKGROUND: Bariatric surgery is an effective long-term weight loss strategy yielding improvements in neurocognitive function; however, the mechanism(s) responsible for these improvements remains unclear. Here, we assessed the feasibility of using magnetic resonance imaging (MRI) to evaluate whether cerebral vascular reactivity (CVR) is impaired in severely obese bariatric surgery candidates compared with normal weight healthy controls and whether CVR improves following bariatric surgery. We also investigated whether changes in CVR were associated with changes in cognitive function. METHODS: Bariatric surgery candidates (n = 6) were compared with normal weight healthy controls of a similar age (n = 10) at baseline, and then reassessed 2 weeks and 14 weeks following sleeve gastrectomy bariatric surgery. Young reference controls (n = 7) were also studied at baseline to establish the range of normal for each outcome measure. Microvascular and macrovascular CVR to hypercapnia (5% CO2) were assessed using blood-oxygen-level-dependent (BOLD) MRI, and changes in the middle cerebral artery (MCA) cross-sectional area, respectively. Cognitive function was assessed using a validated neurocognitive software. RESULTS: Compliance with the CVR protocol was high. Both macro- and micro-cerebrovascular function were highest in the young reference controls. Cognitive function was lower in obese bariatric surgery candidates compared with normal weight controls, and improved by 17% at 2 weeks and 21% by 14 weeks following bariatric surgery. To our surprise, whole-brain CVR BOLD did not differ between obese bariatric surgery candidates and normal weight controls of similar age (0.184 ± 0.101 vs. 0.192 ± 0.034 %BOLD/mmHgCO2), and did not change after bariatric surgery. In contrast, we observed vasoconstriction of the MCA during hypercapnia in 60% of the obese patients prior to surgery, which appeared to be abolished following bariatric surgery. Improvements in cognitive function were not associated with improvements in either CVR BOLD or MCA vasodilation after bariatric surgery. CONCLUSIONS: Assessing CVR responses to a hypercapnic challenge with MRI was feasible in severely obese bariatric patients. However, no changes in whole-brain BOLD CVR were observed following bariatric surgery despite improvements in cognitive function. We recommend that future large trials assess CVR responses to cognitive tasks (rather than hypercapnia) to better define the mechanisms responsible for cognitive function improvements following bariatric surgery.

Near-infrared diffuse correlation spectroscopy tracks changes in oxygen delivery and utilization during exercise with and without isolated arterial compression.

Near-infrared diffuse correlation spectroscopy (NIR-DCS) is an emerging technology for simultaneous measurement of skeletal muscle microvascular oxygen delivery and utilization during exercise. The extent to which NIR-DCS can track acute changes in oxygen delivery and utilization has not yet been fully established. To address this knowledge gap, 14 healthy men performed rhythmic handgrip exercise at 30% maximal voluntary contraction, with and without isolated brachial artery compression, designed to acutely reduce convective oxygen delivery to the exercising muscle. Radial artery blood flow (Duplex Ultrasound) and NIR-DCS derived variables [blood flow index (BFI), tissue oxygen saturation (StO2), and metabolic rate of oxygen (MRO2)] were simultaneously measured. During exercise, both radial artery blood flow (+51.6 ± 20.3 mL/min) and DCS-derived BFI (+155.0 ± 82.2%) increased significantly (P < 0.001), whereas StO2 decreased -7.9 ± 6.2% (P = 0.002) from rest. Brachial artery compression during exercise caused a significant reduction in both radial artery blood flow (-32.0 ± 19.5 mL/min, P = 0.001) and DCS-derived BFI (-57.3 ± 51.1%, P = 0.01) and a further reduction of StO2 (-5.6 ± 3.8%, P = 0.001) compared with exercise without compression. MRO2 was not significantly reduced during arterial compression (P = 0.83) due to compensatory reductions in StO2, driven by increases in deoxyhemoglobin/myoglobin (+7.1 ± 6.1 µM, P = 0.01; an index of oxygen extraction). Together, these proof-of-concept data help to further validate NIR-DCS as an effective tool to assess the determinants of skeletal muscle oxygen consumption at the level of the microvasculature during exercise.

Pathophysiology of Exercise Intolerance and Its Treatment With Exercise-Based Cardiac Rehabilitation in Heart Failure With Preserved Ejection Fraction.

Heart failure with preserved ejection fraction (HFpEF) is the fastest growing form of heart failure in the United States. The cardinal feature of HFpEF is reduced exercise tolerance (peak oxygen uptake, (Equation is included in full-text article.)O2peak) secondary to impaired cardiac, vascular, and skeletal muscle function. There are currently no evidence-based drug therapies to improve clinical outcomes in patients with HFpEF. In contrast, exercise training is a proven effective intervention for improving (Equation is included in full-text article.)O2peak, aerobic endurance, and quality of life in HFpEF patients. This brief review discusses the pathophysiology of exercise intolerance and the role of exercise training to improve (Equation is included in full-text article.)O2peak in clinically stable HFpEF patients. It also discusses the mechanisms responsible for the exercise training-mediated improvements in (Equation is included in full-text article.)O2peak in HFpEF. Finally, it provides evidence-based exercise prescription guidelines for cardiac rehabilitation specialists to assist them with safely implementing exercise-based cardiac rehabilitation programs for HFpEF patients.