Effect of Physical Training on Insulin Resistance in Patients With Chronic Heart Failure

The relationship between skeletal muscle mass and the KOSHA cardiovascular risk in obese male workers

Background

Efforts for the prevention and management of cardiovascular diseases (CVDs) in workers have been actively pursued. Obesity is one of the important risk factors related to CVDs. Obesity has various metabolic characteristics, and some individuals can be metabolically healthy. Body composition including skeletal muscle mass is known to have protective effect in obesity. The study aims to investigate the association between skeletal muscle mass and Korea Occupational Safety and Health Agency (KOSHA) CVD risk among obese male manufacturing workers in Korea and to identify appropriate indicators of skeletal muscle mass for predicting risk of CVDs.

Methods

The study was conducted on 2,007 obese male workers at a manufacturing industry aged more than 19 years. Skeletal muscle mass, skeletal muscle index (SMI), skeletal muscle mass percent (SMM%) and skeletal muscle to body fat ratio (MFR) were used to evaluate body composition and these indicators were divided into quartiles. The odds ratios (ORs) and 95% confidence intervals (CIs) for the KOSHA CVD risk groups according to quartiles of skeletal muscle mass indicators were estimated using ordinal logistic regression analysis.

Results

The OR for the KOSHA CVD risk groups in the highest quartile of SMI was 1.67 (95% CI: 1.42-1.92), while the ORs for the KOSHA CVD risk groups in the highest quartiles of SMM%, SMM/body mass index (BMI), and MFR were 0.47 (95% CI: 0.22-0.72), 0.51 (95% CI: 0.05-0.76), and 0.48 (95% CI: 0.23-0.74), respectively.

Conclusions

We found that high SMI increase the likelihood of high risk of CVDs, while high SMM%, SMM/BMI, and MFR lower the likelihood of high risk of CVDs. Accurate evaluation of skeletal muscle mass can help assess the cardiovascular risk in obese male workers.

Relation of Muscle Mass and Fat Mass to Cardiovascular Disease Mortality

We evaluated the relation between components of body composition and mortality in patients with cardiovascular disease (CVD). Dual x-ray absorptiometry body composition data from the National Health and Nutrition Examination Survey 1999 to 2004 was linked to total and CVD mortality data 1999 to 2006 in 6,451 patients with CVD. Kaplan-Meier survival analysis for the end points of total and CVD mortality was plotted by quartiles of muscle mass, fat mass, and categories of body mass index (BMI). Subjects were stratified into 4 groups (low muscle/low fat mass, low muscle/high fat mass, high muscle/low fat mass, and high muscle/high fat mass). Adjusted Cox proportional hazards regression determined hazard ratios for total and CVD mortality. Rates of cardiovascular/total mortality were lower in higher quartiles of muscle mass, fat mass, and higher categories of BMI (p <0.001). The high muscle/low fat mass group had a lower risk of CVD and total mortality (risk-adjusted hazard ratios of 0.32, 95% confidence interval 0.14 to 0.73 and 0.38, 95% confidence interval 0.22 to 0.68, for CVD and total mortality, respectively). Thus, increasing fat mass, muscle mass, and BMI were all correlated with improved survival. The specific subgroup of high muscle and low fat mass had the lowest mortality risk compared with other body composition subtypes. This suggests the importance of body composition assessment in the prediction of cardiovascular and total mortality in patients with CVD.

Effect of High-Intensity interval training versus moderate continuous training on 24-h blood pressure profile and insulin resistance in patients with chronic heart failure

In patients with chronic heart failure (CHF) blood pressure (BP) control, represents a relevant target of management. This study evaluated the effect of different intensities exercise training on 24-h ambulatory BP profile and insulin resistance in patients with CHF. Thirty-six CHF patients with left ventricular ejection fraction <40%, were randomized to high-intensity interval training (HIT) or moderate continuous training (MIT) for 12 weeks. HIT consisted in treadmill exercise at ~75-80% of heart rate reserve (HRR), alternated with active pauses at 45-50% of HRR. MIT consisted in continuous treadmill at ~45-60% of HRR. Peak VO2 and anaerobic threshold increased significantly with both HIT and MIT, without significant differences between the two training programs. 24-h, systolic and diastolic BP decreased with both HIT and MIT. The same occurred for day-time and night-time systolic and diastolic BP. The decrease in day-time diastolic BP was slightly but significantly greater in HIT. Both HIT and MIT induced a significant decrease in fasting glucose and insulin, whereas HOMA-IR decreased significantly only after HIT. In patients with CHF exercise training reduces BP throughout the day, without substantial differences between moderate and more vigorous exercise intensity, with a small exception for day-time diastolic BP. HIT was more effective in improving insulin resistance.

Exercise training improves cardiac function in infarcted rabbits: involvement of autophagic function and fatty acid utilization

AIMS

To explore whether exercise can improve cardiac function in a post-myocardial infarction (MI) rabbit model and to determine contributing factors in the left ventricle (LV).

METHODS AND RESULTS

Adult male New Zealand White rabbits (2.5-3 kg) underwent MI by ligation of the left anterior descending coronary artery. For 8 weeks after surgery, sham-operated, and post-MI rabbits were housed under sedentary conditions or assigned to a 4-week treadmill exercise protocol at a speed of 1.0 km/h for 30 min 5 days per week, then sacrificed. The non-infarcted region of the LV was harvested for further analysis. MI decreased left ventricular ejection fraction (LVEF) and increased thiobarbituric acid reactive substances (TBARS) generation in the LV. Exercise improved the cardiac function of MI rabbits. Left ventricular LC3II/LC3I (microtubule-associated protein light chain 3) in the MI group was 2.1-fold higher than that of the sham group, exercise significantly decreased LC3II/LC3I in the MI group. MI down-regulated the expression of heart-type fatty acid binding protein (h-FABP), and exercise up-regulated h-FABP. In addition, LVEF had a significantly positive correlation with h-FABP and a negative correlation with LC3II/LC3I.

CONCLUSION

Exercise induced change in autophagic function and fatty acid utilization may contribute to the improvement in ventricular function in the infarcted heart.

Effects of a 14-month low-cost maintenance training program in patients with chronic systolic heart failure: a randomized study

Background

Exercise training is known to be beneficial in chronic heart failure (CH F) patients but there is a lack of studies following patient groups for longer duration with maintenance training programs to defer deconditioning.

Methods

Study base consisted of all patients diagnosed with CHF in a 3-year period. Sixty-six patients with systolic CHF (ejection fraction < 45, New York Heart Association II-III) were randomized to 12 months of either usual care or home-based maintenance exercise with group training sessions every 2 weeks after an initial 8-week training program. The primary endpoint was maximum workload; secondary endpoints were 6-min walk test, incremental shuttle walk test, sit-to-stand test, quality of life, and serological markers.

Results

Six patients died and 43 completed the study. The initial 8-week training was associated with small but significant improvement in all of the functional tests. In both groups there was a significant decline in the maximum workload the next 12 months ( P = 0.03 and P < 0.001, respectively) but after an adjustment for difference between groups in baseline characteristics, maintenance intervention reduced the decline in the maximum workload by 8.0W (95% CI: 3.0–13.0, P = 0.002). No effect of maintenance intervention was observed for 6-min walk test, incremental shuttle walk test, sit-to-stand test, or quality of life. After 14 months changes in most markers of inflammation, endothelial damage, and glycemic control were more beneficial in the intervention group.

Conclusion

A low-cost maintenance intervention in CHF patients reduced the decline in the maximum workload compared with usual care but not in other measures of physical function. Results suggest beneficial effects of long-term maintenance training on glycemic control, inflammation, and endothelial function.

Insulin resistance in pulmonary arterial hypertension

Although obesity, dyslipidemia and insulin resistance (IR) are well known risk factors for systemic cardiovascular disease, their impact on pulmonary arterial hypertension (PAH) is unknown. The present authors' previous studies indicate that IR may be a risk factor for PAH. The current study has investigated the prevalence of IR in PAH and explored its relationship with disease severity. Clinical data and fasting blood samples were evaluated in 81 nondiabetic PAH females. In total, 967 National Health and Nutrition Examination Surveys (NHANES) females served as controls. The fasting triglyceride to high-density lipoprotein cholesterol ratio was used as a surrogate of insulin sensitivity. While body mass index was similar in NHANES versus PAH females (28.6 versus 28.7 kg.m(-2)), PAH females were more likely to have IR (45.7 versus 21.5%) and less likely to be insulin sensitive (IS; 43.2 versus 57.8%). PAH females mostly (82.7%) had New York Heart Association (NYHA) class II and III symptoms. Aetiology, NYHA class, 6-min walk-distance and haemodynamics did not differ between IR and IS PAH groups. However, the presence of IR and a higher NYHA class was associated with poorer 6-months event-free survival (58 versus 79%). Insulin resistance appears to be more common in pulmonary arterial hypertension females than in the general population, and may be a novel risk factor or disease modifier that might impact on survival.

Training rather than walking: the test in -train out program for home-based rehabilitation in peripheral arteriopathy

BACKGROUND

Exercise training reduces walking disability in peripheral arterial disease (PAD). This non-randomized study evaluates the effects on walking ability and hemodynamic parameters of a novel approach to home-based rehabilitation, the test in -train out program (Ti-To), compared with the traditional home-based free walking exercise (Tr-E).

METHODS AND RESULTS

A total of 143 patients with claudication (117 men, average age 68+/-10 years), were included in a Ti-To (n=83) or Tr-E program (n=60). Evaluations, which were carried out upon entry and at 1, 2, 3, 4 and 6 months, included: self-reported claudication, walking ability (ie, absolute claudication distance, pain threshold speed), resting/exercise heart rates (HR), systolic/diastolic brachial pressure (SBP/DBP), ankle pressure (AP), ankle-brachial index (ABI). Ti-To involved 2 daily 10-min home walking sessions at maximal asymptomatic speed and the patient attending monthly check-ups at hospital. Tr-E involved 20-30 min of daily walking at self-selected speeds up to pain tolerance. A total of 126 patients (Ti-To, n=74; Tr-E, n=52) completed the program. Ti-To induced better relief from claudication (p=0.001). Functional parameters improved significantly for both groups (p<0.0001) with significant intergroup difference for Ti-To (p<0.0001). SBP and exercise HR decreased significantly in both groups, with Ti-To improving resting HR (p=0.0002), DBP (p=0.003), lowest AP worse limb (p=0.004) and ABI worse limb (p=0.0002).

CONCLUSIONS

In patients with PAD, a Ti-To program had more positive effects on perceived claudication, and functional and hemodynamic parameters than did a Tr-E program.

Metabolic Mechanisms in Heart Failure

Although neurohumoral antagonism has successfully reduced heart failure morbidity and mortality, the residual disability and death rate remains unacceptably high. Though abnormalities of myocardial metabolism are associated with heart failure, recent data suggest that heart failure may itself promote metabolic changes such as insulin resistance, in part through neurohumoral activation. A detrimental self-perpetuating cycle (heart failure --> altered metabolism --> heart failure) that promotes the progression of heart failure may thus be postulated. Accordingly, we review the cellular mechanisms and pathophysiology of altered metabolism and insulin resistance in heart failure. It is hypothesized that the ensuing detrimental myocardial energetic perturbations result from neurohumoral activation, increased adverse free fatty acid metabolism, decreased protective glucose metabolism, and in some cases insulin resistance. The result is depletion of myocardial ATP, phosphocreatine, and creatine kinase with decreased efficiency of mechanical work. On the basis of the mechanisms outlined, appropriate therapies to mitigate aberrant metabolism include intense neurohumoral antagonism, limitation of diuretics, correction of hypokalemia, exercise, and diet. We also discuss more novel mechanistic-based therapies to ameliorate metabolism and insulin resistance in heart failure. For example, metabolic modulators may optimize myocardial substrate utilization to improve cardiac function and exercise performance beyond standard care. The ultimate success of metabolic-based therapy will be manifest by its capacity further to lessen the residual mortality in heart failure.