Physical Activity, Obesity, and Subclinical Myocardial Damage

Physical activity diminished adverse associations of obesity with lipid metabolism in the population of rural regions of China

The interactive effects of obesity and physical inactivity on lipid metabolism and prevalent dyslipidemia are scarcely reported in rural regions. 39029 subjects were obtained from the Henan Rural Cohort, and their metabolic equivalents (METs) of physical activity (PA) were computed. Independent associations of the obesity indices and PA with either lipid indices or prevalent dyslipidemia were analyzed by generalized linear models, and additive effects of obesity and PA on prevalent dyslipidemia were further quantified. Each obesity index was positively associated with total cholesterol, triglyceride, low-density lipoprotein or prevalent dyslipidemia but negatively associated with high-density lipoprotein, whereas the opposite association of PA with either each lipid index or prevalent dyslipidemia was observed. Joint association of PA and each obesity index with each lipid index and prevalent dyslipidemia was observed. Furthermore, the association of each obesity index in association with each lipid index was attenuated by increased PA levels.

Exploring the Mechanistic Link Between Obesity and Heart Failure

PURPOSE OF REVIEW

Among subtypes of cardiovascular disease, obesity has a potent and unique association with heart failure (HF) that is unexplained by traditional cardiovascular risk mediators. The concomitant rise in the prevalence of obesity and HF necessitates better understanding of their relationship to develop effective prevention and treatment strategies. The purpose of this review is to provide mechanistic insight regarding the link between obesity and HF by elucidating the direct and indirect pathways linking the two conditions.

RECENT FINDINGS

Several direct pathophysiologic mechanisms contribute to HF risk in individuals with excess weight, including hemodynamic alterations, neurohormonal activation, hormonal effects of dysfunctional adipose tissue, ectopic fat deposition with resulting lipotoxicity and microvascular dysfunction. Obesity further predisposes to HF indirectly through causal associations with hypertension, dyslipidemia, and most importantly, diabetes via insulin resistance. Low levels of physical activity and fitness further influence HF risk in the context of obesity. These various processes lead to myocardial injury and cardiac remodeling that are reflected by abnormalities in cardiac biomarkers and cardiac function on myocardial imaging. Understanding and addressing obesity-associated HF is a pressing clinical and public health challenge which can be informed by a deeper understanding of the complex pathways linking these two conditions together.

Association between urinary cadmium level and subclinical myocardial injury in the general population without cardiovascular disease aged ≥ 50 years

Cadmium (Cd) is a toxic heavy metal linked to an increased risk of cardiovascular disease (CVD). But the relationship between urinary Cd (U-Cd) and electrocardiographic subclinical myocardial injury (SC-MI) in older people is unclear. This study evaluated the connection between U-Cd and SC-MI in people who did not have CVD. The study involved 4269 participants from the National Health and Nutrition Examination Survey III(NHANES III) aged ≥ 50 years and had no history of CVD. The relationship between U-Cd and cardiac infarction/injury score (CIIS) was assessed by multivariable linear regression. Whether U-Cd and SC-MI were correlated was determined by multivariate logistic regression, restricted cubic spline, and subgroup analysis. There was a significant association between U-Cd and CIIS (β, 1.04, 95% confidence interval (CI): 0.39-1.69; P = 0.003) in the highest quartile and fully adjusted model. After adjusting for relevant confounders, multivariable logistic regression showed that participants in the highest quartile of U-Cd had a greater chance of having SC-MI than those in the first ( OR (95% CI), 1.37(1.13,1.66), P for trend = 0.003), and this relationship was especially strong among hypertensive participants. And a positive linear correlation between U-Cd and the prevalence of SC-MI was shown by restricted cubic spline analysis. U-Cd may be a novel risk element for SC-MI because it is independently and linearly linked to CIIS and SC-MI.

The effectiveness of diet intervention in improving the metabolism of overweight and obese women: a systematic review and meta-analysis

OBJECTIVES

Dietary therapy may improve glucose and lipid metabolism function in women. However, there is no systematic review to investigate the association between metabolic effects and different dietary interventions in obese women. The main purpose of this study is to summarize the current literature and investigate whether different dietary interventions have an effect on glucose and metabolic indicators of overweight or obese women.

METHODS

We conducted a scoping review of randomized controlled trial (RCT) studies from 1991 to 2022 by adopting a systematic review and meta-analysis. The database includes Google Scholar, PubMed, Embase and Web of Science. Literature screening, data extraction, and quality assessment were independently completed by 2 researchers. Meta-analysis was performed with RevMan.

RESULTS

Twelve articles were extracted and the meta-analysis results showed that the mean difference of metabolic indexes of obese women before and after dietary intervention, including fasting glucose, fasting insulin, HOMA-IR (Homeostasis model assessment-insulin resistance), TG (triglyceride), TC (total cholesterol), LDL-C (low-density lipoprotein cholesterol), HDL-C (high-density lipoprotein cholesterol) are -0.13 [-0.15, -0.10], -2.41 [-3.44, -1.38], -0.13 [-0.15, -0.10], -21.71 [-24.19, -19.22], -21.71 [-24.19, -19.22], -13.29 [-17.86, -8.72], 3.31 [2.22, 4.40], respectively.

CONCLUSIONS

Different dietary interventions benefit glucose and lipid metabolism of overweight or obese women. Further study is needed to determine which specific dietary effects have the greatest effect on improving metabolic indicators.

Prospective assessing metabolic abnormalities, lifestyle and dietary pattern in a Chinese population with heart failure: the MALD-HF study protocol

INTRODUCTION

The evidence on predictive value of lifestyle behaviours and dietary pattern on the prognosis of heart failure (HF) is limited. Our aim is to identify these factors in the setting of secondary prevention of HF.

METHODS AND ANALYSIS

The Metabolic Abnormalities, Lifestyle and Dietary Pattern in Heart Failure study is an ongoing, prospective cohort, single-centre study that aims to recruit 1500 patients with HF from June 2016 to June 2021. At baseline, each participant completes a questionnaire on demographic characteristics, medical history, lifestyle behaviours, sleep duration and quality, bowel movements and regular diet. Biochemical measurements, blood pressure, carotid ultrasound, echocardiography, electrocardiography and cardiac magnetic resonance are obtained and analysed. Muscle strength is assessed using the handgrip dynamometer and the MicroFet2 hand-held dynamometer. Each patient is followed for 5 years or until the occurrence of death. The primary outcome is a composite of cardiovascular mortality or hospitalisation due to worsening heart failure. The secondary end points are cardiovascular deaths and the hospitalisations due to worsening HF. The incidence of mortality and cardiovascular events is documented biennially.

ETHICS AND DISSEMINATION

The study protocol has been approved by the Ethics Committee of the Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, and follows the norms of the World's Association Declaration of Helsinki. The results of this study will be disseminated in peer-reviewed journals and academic conferences.

TRIAL REGISTRATION NUMBER

NCT03951311.

Association between hemoglobin glycation index and subclinical myocardial injury in the general population free from cardiovascular disease

BACKGROUND AND AIMS

The relationship between hemoglobin glycation index (HGI) and the diagnosis and prognosis of cardiovascular disease (CVD) has been verified by previous studies. However, it remains unknown whether HGI has a predictive effect on subclinical myocardial injury (SC-MI). The purpose of the present study was to explore the relationship between HGI and SC-MI in the general population free from CVD.

METHODS AND RESULTS

The present study included 6009 participants free of CVD from the third National Health and Nutrition Examination Survey. Binary Logistic regression analysis was used to tested the association between HGI and SC-MI. As results, the HGI was significantly higher in participants with SC-MI compared with those without, and the HGI was positively correlated with SC-MI and other metabolic disorder parameters. Each 1-unit increase of HGI and glycated hemoglobin A1c (HbA1c) was independently associated with higher risk of SC-MI (P < 0.05), while fasting plasma glucose (FPG) was no longer a predictive indicator of SC-MI with the increase of confounding factors [OR (95% CI): 1.001 (0.999-1.003), P = 0.305]. And in the subgroup analysis, HGI, only in participants without diabetes, was independently associated with higher risk of SC-MI, while HbA1c and FPG had no independent predictive role in both diabetic and non-diabetic participants.

CONCLUSIONS

HGI was a significant predictor of SC-MI in the general population free from CVD.

Exercise Training Increases Serum Cardiac Troponin T Independent of Left Ventricular Mass

The purpose of this study was to determine whether exercise training mediated cardiac troponin T (cTnT) and whether this was associated with increases in left ventricular mass (LVM). Fifty-four sedentary obese women were randomised to high-intensity interval training (HIIT, repeated 4-min cycling at 90% V̇O_2max interspersed with 3-min rest), work-equivalent continuous aerobic training (CAT, continuous cycling at 60% V̇O_2max) or a control group (CON). Resting serum cTnT was assessed using a high-sensitivity assay before and after 12 weeks of training. LVM was determined from 2D echocardiography at the same timepoints. Both HIIT and CAT induced a similar elevation (median 3.07 to 3.76 ng.l^-1, p<0.05) in resting cTnT compared with pre-training and the CON (3.49 to 3.45 ng.l^-1, p>0.05). LVM index in HIIT increased (62.2±7.8 to 73.1±14.1 g.m^-2, p<0.05), but not in CAT (66.1±9.7 to 67.6±9.6 g.m^-2, p>0.05) and CON (67.9±9.5 to 70.2±9.1 g.m^-2, p>0.05). Training-induced changes in resting cTnT did not correlate with changes in LVM index (r=-0.025, p=0.857). These findings suggest that twelve weeks of either HIIT or CAT increased resting cTnT, but the effects were independent of any changes in LVM in sedentary obese women.

Association between exercise habits and stroke, heart failure, and mortality in Korean patients with incident atrial fibrillation: A nationwide population-based cohort study

BACKGROUND

There is a paucity of information about cardiovascular outcomes related to exercise habit change after a new diagnosis of atrial fibrillation (AF). We investigated the association between exercise habits after a new AF diagnosis and ischemic stroke, heart failure (HF), and all-cause death.

METHODS AND FINDINGS

This is a nationwide population-based cohort study using data from the Korea National Health Insurance Service. A retrospective analysis was performed for 66,692 patients with newly diagnosed AF between 2010 and 2016 who underwent 2 serial health examinations within 2 years before and after their AF diagnosis. Individuals were divided into 4 categories according to performance of regular exercise, which was investigated by a self-reported questionnaire in each health examination, before and after their AF diagnosis: persistent non-exercisers (30.5%), new exercisers (17.8%), exercise dropouts (17.4%), and exercise maintainers (34.2%). The primary outcomes were incidence of ischemic stroke, HF, and all-cause death. Differences in baseline characteristics among groups were balanced considering demographics, comorbidities, medications, lifestyle behaviors, and income status. The risks of the outcomes were computed by weighted Cox proportional hazards models with inverse probability of treatment weighting (IPTW) during a mean follow-up of 3.4 ± 2.0 years. The new exerciser and exercise maintainer groups were associated with a lower risk of HF compared to the persistent non-exerciser group: the hazard ratios (HRs) (95% CIs) were 0.95 (0.90-0.99) and 0.92 (0.88-0.96), respectively (p < 0.001). Also, performing exercise any time before or after AF diagnosis was associated with a lower risk of mortality compared to persistent non-exercising: the HR (95% CI) was 0.82 (0.73-0.91) for new exercisers, 0.83 (0.74-0.93) for exercise dropouts, and 0.61 (0.55-0.67) for exercise maintainers (p < 0.001). For ischemic stroke, the estimates of HRs were 10%-14% lower in patients of the exercise groups, yet differences were statistically insignificant (p = 0.057). Energy expenditure of 1,000-1,499 MET-min/wk (regular moderate exercise 170-240 min/wk) was consistently associated with a lower risk of each outcome based on a subgroup analysis of the new exerciser group. Study limitations include recall bias introduced due to the nature of the self-reported questionnaire and restricted external generalizability to other ethnic groups.

CONCLUSIONS

Initiating or continuing regular exercise after AF diagnosis was associated with lower risks of HF and mortality. The promotion of exercise might reduce the future risk of adverse outcomes in patients with AF.

Obesity cardiomyopathy: evidence, mechanisms, and therapeutic implications

The prevalence of heart failure is on the rise and imposes a major health threat, in part, due to the rapidly increased prevalence of overweight and obesity. To this point, epidemiological, clinical, and experimental evidence supports the existence of a unique disease entity termed “obesity cardiomyopathy,” which develops independent of hypertension, coronary heart disease, and other heart diseases. Our contemporary review evaluates the evidence for this pathological condition, examines putative responsible mechanisms, and discusses therapeutic options for this disorder. Clinical findings have consolidated the presence of left ventricular dysfunction in obesity. Experimental investigations have uncovered pathophysiological changes in myocardial structure and function in genetically predisposed and diet-induced obesity. Indeed, contemporary evidence consolidates a wide array of cellular and molecular mechanisms underlying the etiology of obesity cardiomyopathy including adipose tissue dysfunction, systemic inflammation, metabolic disturbances (insulin resistance, abnormal glucose transport, spillover of free fatty acids, lipotoxicity, and amino acid derangement), altered intracellular especially mitochondrial Ca²⁺ homeostasis, oxidative stress, autophagy/mitophagy defect, myocardial fibrosis, dampened coronary flow reserve, coronary microvascular disease (microangiopathy), and endothelial impairment. Given the important role of obesity in the increased risk of heart failure, especially that with preserved systolic function and the recent rises in COVID-19-associated cardiovascular mortality, this review should provide compelling evidence for the presence of obesity cardiomyopathy, independent of various comorbid conditions, underlying mechanisms, and offer new insights into potential therapeutic approaches (pharmacological and lifestyle modification) for the clinical management of obesity cardiomyopathy.

Aerobic exercise improves cardiac function in rats with chronic heart failure through inhibition of the long non-coding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1)

Background

To explore the beneficial effects and underlying mechanisms of aerobic exercise on chronic heart failure (CHF).

Methods

A CHF rat model was induced via left anterior descending coronary artery ligation. Four weeks post-surgery, CHF rats received aerobic exercise training over an 8-week period and cardiac function indexes including xxx were analyzed. To investigate the mechanisms involved in the aerobic exercise-induced benefits on CHF, overexpression of the long non-coding RNA MALAT1 was examined both in vivo and in vitro. Furthermore, the interaction between MALAT1 and the microRNA miR-150-5p and the downstream PI3K/Akt signaling pathway was investigated.

Results

Compared to the control group, the CHF rats showed evidence of left ventricular dysfunction including aggravated cardiac function indexes and lung to body weight ratio. The Masson staining demonstrated a significant degree of blue-stained fibrotic myocardial tissue in CHF rats compared to control rats. Furthermore, the levels of collagen I and collagen II were also markedly increased in CHF rats. Aerobic exercise improved cardiac function and left ventricular remodeling in rats with CHF. There was a significant reduction in the levels of the reactive oxygen species (ROS), inflammatory cytokines including TNF-α, IL-6, and IL-1β, and inflammatory mediums containing the matrix metalloproteinases (MMPs) MMP-2 and MMP-9. Moreover, CHF rats receiving aerobic exercise showed decreased myocardial apoptosis and increased expression of autophagy-related proteins including beclin-1 and LC3B-II. Overexpression of the lncRNA MALAT1 eliminated all the beneficial effects related to aerobic exercise in CHF rats. Subsequent investigations demonstrated that miR-150-5p expression was up-regulated in CHF-Tr rats and down-regulated in CHF-Tr-MALAT1 rats. Furthermore, the downstream PI3K/Akt signaling pathway was re-activated in CHF-Tr-MALAT1 rats. In vitro experiments revealed that overexpression of MALAT1 reduced the miR-150-5p levels, resulting in increased cellular apoptosis and less autophagy. In addition, overexpression of MALAT1 suppressed the downstream PI3K/Akt signaling pathway. Restoring miR-150-5p level with a miR-150-5p mimic decreased the cellular apoptosis and increased autophagy, and the downstream PI3K/Akt signaling pathway was re-activated.

Conclusions

Aerobic exercise improved cardiac function through inhibition of the lncRNA MALAT1 in CHF, and the potential mechanisms may be mediated via the miR-150-5p/PI3K/Akt signaling pathway.

Physical Activity and Incident Heart Failure in High-Risk Subgroups: The ARIC Study

Background

Greater physical activity (PA) is associated with lower heart failure (HF) risk. However, it is unclear whether this inverse association exists across all subgroups at high risk for HF, particularly among those with preexisting atherosclerotic cardiovascular disease.

Methods and Results

We followed 13 810 ARIC (Atherosclerosis Risk in Communities) study participants (mean age 55 years, 54% women, 26% black) without HF at baseline (visit 1; 1987–1989). PA was assessed using a modified Baecke questionnaire and categorized according to American Heart Association guidelines: recommended, intermediate, or poor. We constructed Cox models to estimate associations between PA categories and incident HF within each high‐risk subgroup at baseline, with tests for interaction. We performed additional analyses modeling incident coronary heart disease as a time‐varying covariate. Over a median of 26 years of follow‐up, there were 2994 HF events. Compared with poor PA, recommended PA was associated with lower HF risk among participants with hypertension, obesity, diabetes mellitus, and metabolic syndrome (all P<0.01), but not among those with prevalent atherosclerotic cardiovascular disease (coronary heart disease, stroke, or peripheral arterial disease) (hazard ratio, 0.91; 95% CI, 0.74–1.13 [P interaction=0.02]). Recommended PA was associated with lower risk of incident coronary heart disease (hazard ratio, 0.79; 95% CI, 0.72–0.86), but not with lower HF risk in those with interim coronary heart disease events (hazard ratio, 0.90; 95% CI, 0.78–1.04 [P interaction=0.04]).

Conclusions

PA was associated with decreased HF risk in patients with hypertension, obesity, diabetes mellitus, and metabolic syndrome. Despite a myriad of benefits in patients with atherosclerotic cardiovascular disease, PA may have weaker associations with HF prevention after ischemic disease is established.

Relations Between Physical Activity, Subclinical Myocardial Injury, and Cardiovascular Mortality in the General Population

We examined the association between poor physical activity (PA) and subclinical myocardial injury (SC-MI), and how concomitant exposure to poor PA and SC-MI modifies their association with cardiovascular disease (CVD) mortality. This analysis included 6,044 participants free of CVD from the NHANES-III survey. Leisure time PA was defined as: ideal (3 to 5.99 METs and ≥5 times/week or any PA with ≥6METs and ≥3times/week), intermediate (any activity other than ideal), or poor (no activity at all). SC-MI was defined as an electrocardiographic cardiac infarction/injury score ≥10 units. CVD mortality was ascertained from the National Death Index. In multivariable logistic regression analysis, poor PA (odds ratio [OR] [95% confidence interval, CI]: 1.30 [1.10 to 1.54]) and intermediate PA (OR [95%CI]: 1.19 [1.02 to 1.38]), compared with ideal PA, were associated with an increased odds of SC-MI. During a median follow-up of 14 years, 589 CVD deaths occurred. In multivariable Cox-proportional hazard analysis, the presence (vs absence) of SC-MI was associated with a 33% increased risk of CVD mortality whereas poor (vs ideal) PA was associated with a 67% increased risk of CVD mortality (HR [95%CI]: 1.33 [1.11 to 1.58] and 1.67 [1.37 to 2.05], respectively). Additionally, the concomitant presence of both poor PA and SC-MI were associated with a higher risk of CVD mortality (HR [95%CI]: 2.25[1.68 to 3.00]) compared with ideal PA and the absence of SC-MI. In conclusion, poor PA is associated with an increased risk of SC-MI and their concomitant presence is associated with a marked increase in CVD mortality, underscoring the potential role of PA in preventing clinical and subclinical CVD outcomes.

Visceral adiposity index as a tool for cardiometabolic risk in obese older women

OBJECTIVE: To correlate anthropometric measurements, lipid profile, cardiorespiratory fitness, and visceral adiposity index (VAI) in sedentary obese older women. METHODS: Twenty-seven insufficiently active and overweight older women were included in this cross-sectional study. We evaluated their anthropometric profile (body weight and stature, body mass index, waist and hip circumferences) and body composition (fat mass, body fat percentage, and musculoskeletal mass). Venous blood samples were analyzed for high and low-density lipoproteins (HDL-c and LDL-c), triglycerides (TG), and the LDL/HDL ratio. Peak oxygen uptake (VO2 peak) was measured using an adapted Bruce test using direct spirometry. We tested data normality and applied Pearson’s correlation, assuming a p ≤ 0.05. RESULS: The following correlations were observed: VAI and HDL (r = -0.53); VAI and LDL (r = 0.35); VAI and TG (r = 0.86); VAI and TG/HDL (r = 0.99) and VAI and VO2 peak (r = -0.55), with p < 0.01 for all analyses. CONCLUSION: The findings suggested that VAI may be used as a tool to assess cardiometabolic risk in obese older women. Future studies should evaluate the applicability of VAI as a cardiometabolic risk factor indicator in older adults.

Exercise and heart failure: an update

The present update is dedicated to the evolution of the interaction between heart failure (HF) and exercise and how the scientific community has handled it. Indeed, on the one hand, HF is a leading cause of morbidity and mortality with a stable prevalence from 1998 onward varying between 6.3% and 13.3%. On the other hand, exercise is seen as a diagnostic and prognostic tool as well as a therapeutic intervention in chronic HF. More precisely, the knowledge, the clinical application, and the research interest on the mutual interactions between exercise and HF have different phases in disease progression: Before HF onset (past): exercise provides protective benefit in preventing HF (primary prevention). With HF present: exercise improvement with training provides benefits in HF (secondary prevention). The prediction of future in HF patients: exercise impairment, as a leading characteristic of HF, is used as a prognostic factor.

Six-Year Changes in Physical Activity and the Risk of Incident Heart Failure: ARIC Study

BACKGROUND

Higher physical activity (PA) is associated with lower heart failure (HF) risk; however, the effect of changes in PA on HF risk is unknown.

METHODS

We evaluated 11 351 ARIC study (Atherosclerosis Risk in Communities) participants (mean age 60 years) who attended visit 3 (1993-1995) and did not have a history of cardiovascular disease. Exercise PA was assessed using a modified Baecke questionnaire and categorized according to American Heart Association guidelines as recommended, intermediate, or poor. We used Cox regression models to characterize the association of 6-year changes in PA between the first (1987-1989) and third ARIC visits and HF risk.

RESULTS

During a median of 19 years of follow-up, 1750 HF events occurred. Compared with those with poor activity at both visits, the lowest HF risk was seen for those with persistently recommended activity (hazard ratio, 0.69; 95% confidence interval, 0.60-0.80). However, those whose PA increased from poor to recommended also had reduced HF risk (hazard ratio, 0.77; 95% confidence interval 0.63-0.93). Among participants with poor baseline activity, each 1 SD higher PA at 6 years (512.5 METS*minutes/week, corresponding to ≈30 minutes of brisk walking 4 times per week) was associated with significantly lower future HF risk (hazard ratio, 0.89, 95% confidence interval, 0.82-0.96).

CONCLUSIONS

Although maintaining recommended activity levels is associated with the lowest HF risk, initiating and increasing PA, even in late middle age, are also linked to lower HF risk. Augmenting PA may be an important component of strategies to prevent HF.

Impact of high-intensity interval training and moderate-intensity continuous training on resting and postexercise cardiac troponin T concentration

NEW FINDINGS

What is the central question of this study? Does exercise training impact resting and postexercise cardiac troponin T (cTnT) concentration? What is the main finding and its importance? This randomized controlled intervention study demonstrated that 12 weeks of either high-intensity interval training or moderate-intensity continuous training largely abolished the exercise-induced elevation in cTnT when exercise was performed at the same absolute intensity. There was no impact of training on resting cTnT or postexercise appearance of cTnT when exercise was performed at the same relative intensity. These findings provide new information that might help clinicians with decision-making in relationship to basal and postexercise values of cTnT in individuals with different training status.

ABSTRACT

We evaluated the influence of 12 weeks of high-intensity interval training [HIIT; repeated 4 min cycling at 90% of maximal oxygen uptake (V̇O2max) interspersed with 3 min rest, 200-300 kJ per session, 3 or 4 days each week] and work-equivalent moderate-intensity continuous training (MICT; continuous cycling at 60% V̇O2max) on resting cardiac troponin T (cTnT) and the appearance of exercise-induced cTnT. Forty-eight sedentary obese young women were randomly assigned to HIIT, MICT or a control group. The V̇O2max and body composition were measured before and after training. At baseline, cTnT was assessed using a high-sensitivity assay at rest and immediately, 2 and 4 h after 45 min cycling at 60% V̇O2max. After a 12 week training period, cTnT was assessed before and after 45 min cycling at the same relative and absolute intensities as before training. Training led to higher V̇O2max and lower fat mass in both HIIT and MICT groups (all P < 0.05). Before training, cTnT was significantly elevated in all three groups (by 35-118%, all P < 0.05) with acute exercise. After training, both resting and postexercise cTnT concentrations (same relative intensity) were similar to pretraining values. In contrast, postexercise cTnT (same absolute intensity, which represented a smaller exercise stimulus) was not elevated from rest in both HIIT and MICT groups. In conclusion, 12 weeks of either HIIT or MICT largely abolished the postexercise elevation of cTnT concentration when exercise was performed at the same absolute intensity. There was, however, no impact of training on resting cTnT or postexercise appearance of cTnT for exercise performed at the same relative intensity.

Relationship of Cardiorespiratory Fitness and Adiposity With Left Ventricular Strain in Middle-Age Adults (from the Dallas Heart Study)

Low cardiorespiratory fitness (CRF) and obesity are significant risk factors for heart failure (HF). However, given the inverse association between CRF and obesity, the independent contributions of low CRF and adiposity toward HF risk are not well established. We evaluated the association of CRF and measures of adiposity with left ventricular (LV) peak systolic strain-a subclinical measure of LV dysfunction-among the Dallas Heart Study phase II participants without cardiovascular disease who had CRF estimated using a submaximal treadmill test and LV systolic circumferential strain assessment by tissue-tagged cardiac magnetic resonance imaging. Peak midwall systolic circumferential strain (Ecc) was determined by harmonic phase imaging. Associations of CRF and adiposity measures with Ecc were determined using adjusted linear regression analysis. A total of 1,617 participants were included in the analysis. After adjustment for baseline risk factors, higher waist circumference (WC) and lower CRF were associated with higher Ecc (WC: β = 0.07; p = 0.01; CRF: β = -0.17; p = < 0.0001), whereas % body fat and body mass index were not associated with Ecc. The relationship between WC and Ecc was attenuated completely after additional adjustment for CRF. In contrast, the association between CRF and Ecc did not attenuate after additional adjustment for WC and other measures of LV structure and function (β = -0.18; p = < 0.0001). Taken together, our study findings suggest that lower CRF, but not measures of adiposity, is associated with greater impairment in LV strain independent of LV mass and ejection fraction.