Cardiac rehabilitation utilization, barriers, and outcomes among patients with heart failure.

Exercise-based cardiac rehabilitation (CR) is effective for improving both primary (i.e., mortality and hospitalizations) and secondary (i.e., functional capacity and quality of life among) clinical outcomes among patients with heart failure (HF). The mechanisms that explain these benefits are complex and are linked to exercise adaptations such as central and peripheral hemodynamics combined with improved overall medical management. Despite the benefits of CR, utilization rates are low among CR eligible patients. Clinician-, patient-, and health system-related barriers have been identified as primary factors contributing to the lack of CR utilization among HF patients. These include patient referrals (clinician-related), psychosocial factors (patient-related), and patient access to CR services (health system-related). The aims of this review are to detail the components of each barrier as well as identify evidence-based strategies to improve CR utilization and adherence among HF. The improvements in primary and secondary outcomes along with the mechanisms that are linked to these changes will also be examined.

Comparison of Wrist- and Hip-Worn Activity Monitors When Meeting Step Guidelines.

INTRODUCTION: Physical activity (PA) guidelines aimed at accumulating 10,000 steps per day have become increasingly common with the advent of wristband PA monitors. However, accumulated steps measured with wristband PA monitors may not be equal to steps measured with validated, hip-worn pedometers. Consequently, evaluating and developing guidelines for step counts using wristband PA monitors for the general population is needed. We compared step counts accumulated with hip-worn pedometers with those accumulated with wrist-worn activity monitors during 1) treadmill exercise, 2) treadmill walking, and 3) activities of daily living (ADL) to determine their accuracy in meeting step count guidelines (ie, 10,000 steps/d). METHODS: Eighty-six adults (aged 18-65 y; body mass index, 19-45 kg/m2) completed 30 minutes of treadmill exercise while simultaneously using a hip-worn pedometer and wrist-worn PA monitor. Remaining steps needed to reach 10,000 steps (ie, 10,000 steps minus the number of pedometer steps recorded from treadmill exercise = remainder) were completed via treadmill walking or ADL. Steps were recorded for both devices after treadmill exercise, treadmill walking, and ADL for both devices. RESULTS: Fewer steps were accumulated via wrist-worn PA monitors than via hip-worn pedometers during treadmill exercise (3,552 [SD, 63] steps vs 3,790 [SD, 55] steps, P < .01) and treadmill walking (5,877 [SD, 83] steps vs 6,243 [SD, 49] steps, P < .01). More steps were accumulated via wrist-worn PA monitors than hip-worn pedometers during ADL (7,695 [SD, 207] steps vs 6,309 [SD, 57] steps, P < .01). Consequently, total steps were significantly higher for wristband PA monitors than hip-worn pedometers (11,247 [SD, 210] steps vs 10,099 [SD, 39] steps; P < .01). CONCLUSION: The widely used 10,000-step recommendation may not be accurate for all users of all activity monitors, given the discrepancy in daily step count among wrist-worn and hip-worn devices. Having a more accurate indication of number of steps taken per day based on the device used could have positive effects on health.

Exercise During Pregnancy: What Do OB/GYNs Believe and Practice? A Descriptive Analysis.

Introduction: Although regular exercise is recommended during non-complicated pregnancies to promote maternal and fetal/infant health, estimates suggest that only 15% of expectant mothers achieve current exercise recommendations. Although lack of motivation and fear related to potential fetal injury are often cited as reasons for not engaging in regular physical activity/exercise during pregnancy, less is understood about individual attitudes and practice habits of obstetrician and gynecologists (OB/GYNs) regarding exercise recommendations that may influence patient engagement in exercise during pregnancy. Purpose: To describe the attitudes, knowledge, and clinical practice of OB/GYNs regarding exercise during pregnancy. Methods: Surveys were sent via U.S. mail to 950 practicing OB/GYNs identified via publicly available databases. The survey included 11 questions regarding demographic information, exercise physiology knowledge, as well as their attitudes and clinical practice recommendations regarding exercise during pregnancy. Results: One hundred thirty-nine completed surveys were returned (14.6% response rate). Ninety-four percent of physicians surveyed agreed that there are benefits of exercise during pregnancy and/or the benefits of exercise during pregnancy outweigh the risks. Ninety-eight percent of physicians surveyed reported that they (or their medical staff) routinely advise their patients to exercise during pregnancy and 46% reported discussing exercise guidelines related to time, intensity, and type of exercise. Only 13% of physicians surveyed reported taking a semester-long exercise physiology course, yet 27% of physicians surveyed reported developing personalized exercise prescriptions for all (6%) or some (21%) of their patients. Conclusions: Low exercise engagement among expectant mothers does not appear to be due to a lack of guidance or negative views of OB/GYNs regarding exercise during pregnancy.

Effect of Type-2 Diabetes Mellitus on Cardiac Rehabilitation Outcomes: A Meta-analysis.

OBJECTIVE: To determine the effect of cardiac rehabilitation (CR) on changes in functional capacity among patients with cardiovascular disease (CVD) and a type 2 diabetes mellitus (T2D) comorbidity compared with patients without T2D. DATA SOURCES: A systematic review and meta-analysis of randomized controlled trials were completed using PubMed, Cumulative Index to Nursing and Allied Health, and Web of Science in January 2021. STUDY SELECTION: Articles were included if they compared patients CR with T2D with those without T2D. DATA EXTRACTION: The primary outcome variable was functional capacity change from pre- to post CR reported as maximum or peak oxygen consumption and peak metabolic equivalent (METs). Risk of bias was assessed using the Cochrane Risk of Bias Tool. A random-effects model subgroup meta-analysis was conducted. A diabetes comorbidity was selected for the subgroup analysis with patients with CVD having conditions reported as T2D or non-T2D. DATA SYNTHESIS: Twelve studies with total sample of 15,672 patients were extracted. Average change in peak METs was 1.41±1.76 among non-T2D and 1.08±1.57 among T2D after CR. Change in functional capacity was significantly lower among patients with T2D (z value=2.14; g=-0.42; 95% CI, -0.86 to -0.01; P=.03). CONCLUSIONS: Patients with CVD with T2D experience less robust improvements in functional capacity in response to CR compared with patients with CVD alone. A better understanding of the relationship between T2D and functional capacity vital step in informing exercise prescription in CR for patients with T2D and CVD. The lack of understanding the role of T2D onset and progression is a limitation to this study.

Exercise Prescription Guidelines for Cardiovascular Disease Patients in the Absence of a Baseline Stress Test.

Aerobic exercise is a core component of cardiac rehabilitation (CR). Leading organizations recommend that the exercise prescriptions should be based on a symptom limited baseline graded exercise test (GXT). However, recent evidence suggests that only ~30% of CR clinics perform baseline GXTs. Consequently, exercise prescriptions including exercise progression in CR are not following standard exercise prescription guidelines. Therefore, the purpose of this review is to provide clinicians with evidence-based techniques for prescribing exercise in the absence of a baseline GXT. Intensity indicators (e.g., heart rate, perceived exertion) are reviewed, along with special exercise considerations for various disease states (e.g., heart failure, peripheral artery disease, and coronary artery disease). Baseline exercise testing remains the gold standard approach for prescribing exercise among heart disease patients, however, clinicians must be prepared to safely develop and monitor patients when a baseline GXT is not performed.

Changes in markers for cardio-metabolic disease risk after only 1-2 weeks of a high saturated fat diet in overweight adults.

PURPOSE: Diets high in saturated fat acids (SFA) have been linked with cardio-metabolic disease risk. The purpose of this study was to determine whether only 1-2 weeks of a high SFA diet could impact disease risk factors in overweight adults who normally eat a relatively low proportion of SFA (i.e., <40% of dietary fat). METHODS: Twelve overweight (BMI: 27±1 kg/m2) young adults were studied before and after a 2-week diet that increased the proportion of SFA (<40% to 60% of dietary fat), while maintaining their daily intake of total fat, carbohydrate, protein, and calories. Insulin resistance, blood pressure, plasma markers of liver damage, total plasma cholesterol concentrations, and fatty acid profile within plasma and skeletal muscle lipid pools were assessed before and after the intervention. RESULTS: Total plasma cholesterol concentration increased (148±5 vs. 164±8 mg/dl; P<0.05) after only one week, due exclusively to an increase in LDL-cholesterol (78±4 vs. 95±7 mg/dl; P<0.05). After two weeks, plasma aspartate amino transferase (AST) concentration increased (P<0.05) but we found no change in insulin resistance, or resting blood pressure. The diet increase the proportion of SFA in plasma (35±1% vs. 39±2%; P<0.05) and the intramyocellular triglyceride pool (32±1% vs. 37±1%; P<0.05) suggesting the fatty acids in these pools may readily exchange. CONCLUSIONS: Although blood lipids remain within normal clinical range, increasing saturated fat in diet for only 2 weeks raises plasma markers of cardiovascular risk (LDL-cholesterol) and liver damage (AST). In overweight, but healthy-young adults SFA accumulate in plasma and muscle after only 1-2 weeks of dietary increase.

Objective and subjective measures of exercise intensity during thermo-neutral and hot yoga.

While hot yoga has gained enormous popularity in recent years, owing in part to increased environmental challenge associated with exercise in the heat, it is not clear whether hot yoga is more vigorous than thermo-neutral yoga. Therefore, the aim of this study was to determine objective and subjective measures of exercise intensity during constant intensity yoga in a hot and thermo-neutral environment. Using a randomized, crossover design, 14 participants completed 2 identical ∼20-min yoga sessions in a hot (35.3 ± 0.8 °C; humidity: 20.5% ± 1.4%) and thermo-neutral (22.1 ± 0.2 °C; humidity: 27.8% ± 1.6%) environment. Oxygen consumption and heart rate (HR) were recorded as objective measures (percentage of maximal oxygen consumption and percentage of maximal HR (%HRmax)) and rating of perceived exertion (RPE) was recorded as a subjective measure of exercise intensity. There was no difference in exercise intensity based on percentage of maximal oxygen consumption during hot versus thermo-neutral yoga (30.9% ± 2.3% vs. 30.5% ± 1.8%, p = 0.68). However, exercise intensity was significantly higher during hot versus thermo-neutral yoga based on %HRmax (67.0% ± 2.3% vs. 60.8% ± 1.9%, p = 0.01) and RPE (12 ± 1 vs. 11 ± 1, p = 0.04). According to established exercise intensities, hot yoga was classified as light-intensity exercise based on percentage of maximal oxygen consumption but moderate-intensity exercise based on %HRmax and RPE while thermo-neutral yoga was classified as light-intensity exercise based on percentage of maximal oxygen uptake, %HRmax, and RPE. Despite the added hemodynamic stress and perception that yoga is more strenuous in a hot environment, we observed similar oxygen consumption during hot versus thermo-neutral yoga, classifying both exercise modalities as light-intensity exercise.

Effects of aerobic interval training on arterial stiffness and microvascular function in patients with metabolic syndrome.

The authors determined the effect of high-intensity aerobic interval training on arterial stiffness and microvascular dysfunction in patients with metabolic syndrome with hypertension. Applanation tonometry was used to measure arterial stiffness and laser Doppler flowmetry to assess microvascular dysfunction before and after 6 months of stationary cycling (training group; n = 23) in comparison to a group that remained sedentary (control group; n = 23). While no variable improved in controls, hypertension fell from 79% (59%-91%) to 41% (24%-61%) in the training group, resulting in lower systolic and diastolic pressures than controls (-12 ± 3 and -6 ± 2 mm Hg, P < .008). Arterial stiffness declined (-17% augmentation index, P = .048) and reactive hyperemia increased (20%, P = .028) posttreatment in the training group vs controls. Blood constituents associated with arterial stiffness and a prothrombotic state (high-sensitivity C-reactive protein, fibrinogen, platelets, and erythrocytes) remained unchanged in the training and control groups. In summary, 6 months of an intense aerobic exercise program reduced both arterial stiffness and microvascular dysfunction in patients with metabolic syndrome despite unchanged blood-borne cardiovascular risk factors. Training lowers blood flow resistance in central and peripheral vascular beds in a coordinated fashion, resulting in clinically relevant reductions in hypertension.

Dietary supplementation with omega-3 fatty acids and oleate enhances exercise training effects in patients with metabolic syndrome.

OBJECTIVE: We studied the effects of exercise training alone or combined with dietary supplementation of omega-3 polyunsaturated fatty acids (Ω-3PUFA) and oleate on metabolic syndrome (MSyn) components and other markers of cardiometabolic health. METHODS: Thirty-six patients with MSyn underwent 24 weeks of high-intensity interval training. In a double-blind randomized design, half of the group ingested 500 mL/day of semi-skim milk (8 g of fat; placebo milk) whereas the other half ingested 500 mL/day of skim milk enriched with 275 mg of Ω-3PUFA and 7.5 g of oleate (Ω-3 + OLE). RESULTS: Ω-3 + OLE treatment elevated 30% plasma Ω-3PUFA but not significantly (P = 0.286). Improvements in VO2peak (12.8%), mean blood pressure (-7.1%), waist circumference (-1.8%), body fat mass (-2.9%), and trunk fat mass (-3.3%) were similar between groups. However, insulin sensitivity (measured by intravenous glucose tolerance test), serum concentration of C-reactive protein, and high-density lipoprotein improved only in the Ω-3 + OLE group by 31.5%, 32.1%, and 10.3%, respectively (all P < 0.05). Fasting serum triacylglycerol, glucose, and plasma fibrinogen concentrations did not improve in either group after 24 weeks of intervention. CONCLUSIONS: Diet supplementation with Ω-3PUFA and oleate enhanced cardiometabolic benefits of intense aerobic exercise training in patients with MSyn.

Relationship between muscle water and glycogen recovery after prolonged exercise in the heat in humans.

PURPOSE: It is usually stated that glycogen is stored in human muscle bound to water in a proportion of 1:3 g. We investigated this proportion in biopsy samples during recovery from prolonged exercise. METHODS: On two occasions, nine aerobically trained subjects ([Formula: see text] = 54.4 ± 1.05 mL kg(-1) min(-1); mean ± SD) dehydrated 4.6 ± 0.2 % by cycling 150 min at 65 % [Formula: see text] in a hot-dry environment (33 ± 4 °C). One hour after exercise subjects ingested 250 g of carbohydrates in 400 mL of water (REHLOW) or the same syrup plus water to match fluid losses (i.e., 3170 ± 190 mL; REHFULL). Muscle biopsies were obtained before, 1 and 4 h after exercise. RESULTS: In both trials muscle water decreased from pre-exercise similarly by 13 ± 6 % and muscle glycogen by 44 ± 10 % (P < 0.05). After recovery, glycogen levels were similar in both trials (79 ± 15 and 87 ± 18 g kg(-1) dry muscle; P = 0.20) while muscle water content was higher in REHFULL than in REHLOW (3814 ± 222 vs. 3459 ± 324 g kg(-1) dm, respectively; P < 0.05; ES = 1.06). Despite the insufficient water provided during REHLOW, per each gram of glycogen, 3 g of water was stored in muscle (recovery ratio 1:3) while during REHFULL this ratio was higher (1:17). CONCLUSIONS: Our findings agree with the long held notion that each gram of glycogen is stored in human muscle with at least 3 g of water. Higher ratios are possible (e.g., during REHFULL) likely due to water storage not bound to glycogen.

Acute exercise ameliorates differences in insulin resistance between physically active and sedentary overweight adults.

Although regular exercise is associated with reduced cardiometabolic disease risk among overweight adults, it remains unclear whether much of the health benefits of exercise are derived from the most recent session(s) of exercise or if they are the result of adaptations stemming from weeks, months, or even years of training. The purpose of this study was to compare the effects of habitual and acute exercise on key markers of cardiometabolic disease risk in overweight adults. We compared insulin sensitivity index (ISI) using an oral glucose tolerance test, blood pressure (BP), blood lipids, and systemic inflammatory cytokines in 12 overweight to mildly obese adults (BMI: 27-34 kg/m(2)) who exercise regularly (EX; >2.5 h exercise per week) with a well-matched cohort of 12 nonexercisers (Non-EX). Baseline measurements in EX were performed exactly 3 days after exercise, whereas Non-EX remained sedentary. We repeated these measurements the day after a session of exercise in both groups. At baseline, ISI was significantly greater in EX versus Non-EX (3.1 ± 0.2 vs. 2.3 ± 0.2; p = 0.02), but BP, blood lipids, and plasma concentration of the systemic inflammatory cytokines we measured were not different between groups. Acute exercise increased ISI the next morning in Non-EX (2.3 ± 0.2 vs. 2.8 ± 0.3; p = 0.03) but not EX. As a result, ISI was similar between groups the morning after exercise. In summary, exercising regularly was accompanied by a persistent improvement in insulin sensitivity that lasted at least 3 days after exercise in overweight adults, but just one session of exercise increased insulin sensitivity among sedentary overweight adults to levels equivalent to the regular exercisers.

Rapid development of systemic insulin resistance with overeating is not accompanied by robust changes in skeletal muscle glucose and lipid metabolism.

Prolonged overeating and the resultant weight gain are clearly linked with the development of insulin resistance and other cardiometabolic abnormalities, but adaptations that occur after relatively short periods of overeating are not completely understood. The purpose of this study was to characterize metabolic adaptations that may accompany the development of insulin resistance after 2 weeks of overeating. Healthy, nonobese subjects (n = 9) were admitted to the hospital for 2 weeks, during which time they ate ∼4000 kcals·day(-1) (70 kcal·kg(-1) fat free mass·day(-1)). Insulin sensitivity was estimated during a meal tolerance test, and a muscle biopsy was obtained to assess muscle lipid accumulation and protein markers associated with insulin resistance, inflammation, and the regulation of lipid metabolism. Whole-body insulin sensitivity declined markedly after 2 weeks of overeating (Matsuda composite index: 8.3 ± 1.3 vs. 4.6 ± 0.7, p < 0.05). However, muscle markers of insulin resistance and inflammation (i.e., phosphorylation of IRS-1-Ser(312), Akt-Ser(473), and c-Jun N-terminal kinase) were not altered by overeating. Intramyocellular lipids tended to increase after 2 weeks of overeating (triacylglyceride: 7.6 ± 1.6 vs. 10.0 ± 1.8 nmol·mg(-1) wet weight; diacylglyceride: 104 ± 10 vs. 142 ± 23 pmol·mg(-1) wet weight) but these changes did not reach statistical significance. Overeating induced a 2-fold increase in 24-h insulin response (area under the curve (AUC); p < 0.05), with a resultant ∼35% reduction in 24-h plasma fatty acid AUC (p < 0.05). This chronic reduction in circulating fatty acids may help explain the lack of a robust increase in muscle lipid accumulation. In summary, our findings suggest alterations in skeletal muscle metabolism may not contribute meaningfully to the marked whole-body insulin resistance observed after 2 weeks of overeating.

Daily physical activity predicts degree of insulin resistance: a cross-sectional observational study using the 2003-2004 National Health and Nutrition Examination Survey.

BACKGROUND: This study examined the independent association of objectively measured physical activity on insulin resistance while controlling for confounding variables including: cardiorespiratory fitness, adiposity, sex, age, and smoking status. METHODS: Data were obtained from National Health and Nutrition Examination Survey 2003-2004, a cross-sectional observational study conducted by the National Center for Health Statistics of the Centers for Disease Control that uses a stratified, multistage probability design to obtain a nationally representative sample of the U.S. population. The analysis included 402 healthy U.S. adults with valid accelerometer, cardiorespiratory fitness, and fasting plasma glucose and insulin concentrations. After controlling for relevant confounding variables we performed a multiple linear regression to predict homeostatic model of insulin resistance (HOMA-IR) based on average daily minutes of moderate-to-vigorous physical activity (MVPA). RESULTS: In our bivariate models, MVPA, cardiorespiratory fitness and body fat percentage were all significantly correlated with log HOMA-IR. In the complete model including MVPA and relevant confounding variables, there were strong and significant associations between MVPA and log HOMA-IR (ß= -0.1607, P=0.004). In contrast the association between cardiorespiratory fitness and log HOMA-IR was not significant. CONCLUSION: When using an objective measure of physical activity the amount of time engaged in daily physical activity was associated with lower insulin resistance, whereas higher cardiorespiratory fitness was not. These results suggest that the amount of time engaged in physical activity may be an important determinant for improving glucose metabolism.