Impact of diabetes on muscle mass, muscle strength, and exercise tolerance in patients after coronary artery bypass grafting

Factors Affecting Recovery of 6-Minute Walk Distance After Coronary Artery Bypass Grafting

Background: This single-center retrospective analysis investigated the number of days required for postoperative 6-minute walk distance (6MWD) to recover to preoperative values after coronary artery bypass grafting (CABG) and the factors influencing this recovery. Methods and Results: The 6MWD was measured in 101 patients (median age 69 years; 18 women) before and every day after CABG. Univariate and multivariate analyses were performed to identify factors affecting 6MWD recovery to preoperative values after CABG. The median number of days required for recovery of 6MWD after CABG was 9 (interquartile range 7-11 days). Patients were divided into 2 groups based on the median number of days required for recovery of 6MWD; there were 60 patients in the early recovery group (<9 days) and 41 in the "non-early" recovery group (38 who recovered after the median 9 days, and 3 who did not recover during hospitalization). Using univariate logistic regression analysis, diabetes (P=0.01), stroke (P=0.26), left ventricular ejection fraction (P=0.27), and grip strength (P=0.13) were selected for multivariate analysis. Multivariate logistic regression analysis revealed that diabetes (odds ratio 2.955; 95% confidence interval 1.208-7.229; P=0.02) was the only independent predictor of 6MWD recovery. Conclusions: Diabetes was the single factor influencing the recovery of postoperative 6MWD in patients undergoing CABG.

Neuromuscular electrical stimulation after cardiovascular surgery mitigates muscle weakness in older individuals with diabetes

BACKGROUND

Cardiovascular surgery leads to postsurgical muscle weakness, probably because of muscle proteolysis and peripheral nerve dysfunction, which are augmented by aging and diabetes mellitus.

OBJECTIVE

We examined the effect of neuromuscular electrical stimulation (NMES) on postsurgical muscle weakness in older individuals with diabetes mellitus.

METHODS

We conducted a multicentre, randomized, controlled trial, and screened consecutive patients with diabetes who underwent cardiovascular surgery for eligibility (age ≥ 65 years). Those included were randomly assigned to the NMES or the sham group. The primary outcome was the percent change in isometric knee extension strength (%ΔIKES) from preoperative to postoperative day 7. Secondary outcomes were the percent change in usual (%ΔUWS), maximum walking speed (%ΔMWS), and grip strength (%ΔGS). A statistician who was blinded to group allocation used intention-to-treat analysis (student t test).

RESULTS

Of 1151 participants screened for eligibility, 180 (NMES, n = 90; sham, n = 90) were included in the primary analysis. %ΔIKES was significantly lower in the NMES than sham group (NMES: mean -2%, 95% confidence interval [CI] -6 to 1; sham: -13%, 95% CI -17 to -9, p < 0.001). Among the secondary outcomes, %ΔMWS was significantly lower and %ΔUWS and %ΔGS were lower, although not significantly, in the NMES than sham group.

CONCLUSIONS

A short course of NMES (< 1 week) mitigated postsurgical muscle weakness and functional decline in older persons with diabetes mellitus. NMES could be recommended as a part of postsurgical rehabilitation in older people with diabetes mellitus, especially those with a low functional reserve.

Potential Mechanisms for How Long-Term Physical Activity May Reduce Insulin Resistance

Insulin became available for the treatment of patients with diabetes 100 years ago, and soon thereafter it became evident that the biological response to its actions differed markedly between individuals. This prompted extensive research into insulin action and resistance (IR), resulting in the universally agreed fact that IR is a core finding in patients with type 2 diabetes mellitus (T2DM). T2DM is the most prevalent form of diabetes, reaching epidemic proportions worldwide. Physical activity (PA) has the potential of improving IR and is, therefore, a cornerstone in the prevention and treatment of T2DM. Whereas most research has focused on the acute effects of PA, less is known about the effects of long-term PA on IR. Here, we describe a model of potential mechanisms behind reduced IR after long-term PA to guide further mechanistic investigations and to tailor PA interventions in the therapy of T2DM. The development of such interventions requires knowledge of normal glucose metabolism, and we briefly summarize an integrated physiological perspective on IR. We then describe the effects of long-term PA on signaling molecules involved in cellular responses to insulin, tissue-specific functions, and whole-body IR.

American Medical Society for Sports Medicine Position Statement on the Care of the Athlete and Athletic Person With Diabetes

ABSTRACT

The American Medical Society for Sports Medicine (AMSSM) developed this position statement to assist physicians and other health professionals in managing athletes and active people with diabetes. The AMSSM selected the author panel through an application process to identify members with clinical and academic expertise in the care of active patients with diabetes. This article reviews the current knowledge and gaps regarding the benefits and risks of various types of exercise and management issues for athletes and physically active people with diabetes, including nutrition and rehabilitation issues. Resistance exercises seem to be beneficial for patients with type 1 diabetes, and the new medications for patients with type 2 diabetes generally do not need adjustment with exercise. In preparing this statement, the authors conducted an evidence review and received open comment from the AMSSM Board of Directors before finalizing the recommendations.

The Association Between Arterial Stiffness and Muscle Indices Among Healthy Subjects and Subjects With Cardiovascular Risk Factors: An Evidence-Based Review

Skeletal muscle is one of the major tissues in the body and is important for performing daily physical activity. Previous studies suggest that vascular dysfunction contributes to reduced skeletal muscle mass. However, the association between vascular dysfunction and muscle mass, muscle strength and muscle flexibility are less established. Therefore, the focus of this review was to investigate the association between arterial stiffness (AS) which is a marker of vascular function, and muscle indices among healthy and those with cardiovascular risk factors. Three databases were used to search for relevant studies. These keywords were used: "arterial stiffness" OR "vascular stiffness" OR "aortic stiffness" OR "pulse wave velocity" OR "carotid femoral pulse wave velocity" OR "pulse wave analysis" AND "muscle" OR "skeletal" OR "flexibility" OR "range of motion" OR "articular" OR "arthrometry" OR "strength" OR "hand strength" OR "pinch strength" OR "mass" OR "lean" OR "body composition." The criteria were; (1) original, full-text articles, (2) articles written in English language, (3) human studies involving healthy adults and/or adults with cardiovascular disease (CVD) or CVD risk factors (4) articles that reported the relationship between AS (measured as carotid-femoral pulse wave velocity or brachial-ankle pulse wave velocity) and muscle indices (measured as muscle mass, muscle flexibility and muscle strength) after adjusting for relevant confounders. The search identified 2295 articles published between 1971 and June 2021. Only 17 articles fulfilled the criteria. Two studies showed an inverse association between AS and muscle strength in healthy subjects, whereas in subjects with CVD risk factors, five out of seven studies found an inverse correlation between the two parameters. Eleven studies showed an inverse association between AS and muscle mass in subjects with CVD and CVD risk factors. The association between AS and muscle flexibility was not studied in any of the articles reviewed. In conclusion, there is an inverse correlation between muscle indices and AS in healthy adults and those with CVD or CVD risk factors. However, most of the studies were cross-sectional studies, hence the need for future prospective studies to address this issue.

Association Between Constipation and Frailty Components in Patients Undergoing Late Phase II Cardiac Rehabilitation

Background

The Japanese Ministry of Health, Labour and Welfare reported that the overall constipation complaint rates among men and women are 2.5% and 4.6%, respectively. To evaluate the impact of constipation on patients with cardiovascular diseases, we investigated the association between constipation and frailty components in patients undergoing cardiac rehabilitation (CR).

Methods

We enrolled 102 consecutive patients undergoing late phase II CR (mean age: 62.7 ± 13.4 years; 68 (67%) were men). We investigated clinical characteristics, observed defecation status and evaluated frailty components assessed by the Kihon checklist. According to the Clinical Guidelines for Chronic Constipation, the subjects were divided into constipation and non-constipation groups.

Results

Constipation was noted in 33 patients (32%). Interestingly, the constipation complaint rate was only 15%. Age was significantly higher in the constipation group than in the non-constipation group; however, no differences in sex, underlying diseases and prevalence rates of coronary risk factors were observed between the two groups. Body mass index, hemoglobin level, albumin level and estimated glomerular filtration rate were significantly lower in the constipation group than in the non-constipation group. The prevalence of frailty was significantly higher in the constipation group than in the non-constipation group. Physical ability, seclusion and depression scores were significantly higher in the constipation group than the non-constipation group.

Conclusions

Constipation was associated with physical function and depression score as components of frailty in patients undergoing CR.

The association between healthy lifestyle score with cardiorespiratory fitness and muscle strength

OBJECTIVE

The association of individual behaviours such as diet, tobacco use, body mass index (BMI) and physical activity have been investigated separately in relevance to cardiorespiratory fitness (CRF) and muscle strength. The purpose of this study is to investigate the combined association of the four mentioned lifestyle factors with cardiorespiratory fitness and muscle strength.

METHODS

This cross-sectional study was conducted on 271 Iranian adults, aged 18-70 years. We developed a healthy lifestyle score (HLS) that ranged from 0 to 103 (higher score reflecting better adherence to healthier lifestyle) and included four lifestyle behavioural components (diet, physical activity, smoking and BMI). The relationship between HLS, CRF and muscle strength was determined using linear and non-linear regression analysis.

RESULTS

HLS score was not significantly associated with VO_2max (mL/kg/min) P = .43; VO_2max (L min) P = .14; VO_2max (LBM) (P = .79) and mean muscle strength (MMS) (kg) (P = .11), muscle strength of right hand (MSR) (kg) (P = .10) and muscle strength of left hand (MSL) (kg) (P = .16) in the unadjusted model. After adjustment for potential confounders, we found a significant association between HLS and Vo_2max (L/min), MMS (kg), MSR (kg) and MSL (kg) (P < .001 for all). Also HLS and MMS (r = .06, P = .31), MSR (r = .07, P = .25), MMS (r = .05, P = .39), VO_2max (mL/kg/min) (r = .01, P = .77), VO_2max (L min) (r = .05, P = .35) and VO_2max (LBM) (r = .002, P = .91) have no statistically significant linear relationship.

CONCLUSION

Adherence to healthy lifestyle may be associated with increased CRF and muscle strength after adjusting for potential confounding variables.

Effects of lifestyle interventions on rural patients with type 2 diabetes mellitus

BACKGROUND

The prevalence of type 2 diabetes mellitus (T2DM) is rising rapidly in rural areas, and lifestyle interventions can effectively reduce the blood glucose levels of patients with T2DM. However, current dietary and exercise guidelines are still at experimental stages and are difficult for subjects to understand and implement. The Human Metabolism Analyzer provides real life interventions for the prevention and treatment of T2DM, and our pilot research has demonstrated its effectiveness and good compliance.

AIM

To investigate the effect of and compliance with lifestyle interventions in rural patients with T2DM.

METHODS

A total of ten rural villages were randomly selected in Chaoshui Township, Penglai City, Shandong Province, China, to conduct health screening among residents aged 50 years or older. Each rural village represented a group, and 12 patients with T2DM were randomly selected from each group (total: 120) to participate in this study and receive real life lifestyle interventions and medication guidance. Lifestyle interventions included changing the meal order (A), postprandial activities (B), resistance exercise (C), and reverse abdominal breathing (D). Diabetes education was conducted at least once a month with a weekly phone follow-up to monitor exercise and diet. Waist circumference, blood pressure, body mass index (BMI), motor function, body composition, fasting blood glucose, and glycated hemoglobin (HbA1c) were analyzed before and 3 mo after the intervention. Moreover, patient compliance and adjustments of hypoglycemic drugs were evaluated.

RESULTS

A total of 109 subjects completed the study. The compliance rates for lifestyle interventions A, B, C, and D were 57.79%, 60.55%, 64.22%, and 75.23%, respectively. Among the subjects who received hypoglycemic drugs, the dose was reduced 2 to 3 times based on blood glucose in 54 (67.50%) subjects and was tapered and discontinued in 5 (6.25%) subjects within 3 mo, with no significant fluctuations in blood glucose after dose reduction and withdrawal. After lifestyle interventions, waist circumference, BMI, fasting blood glucose, and HbA1c significantly decreased (P < 0.001); motor function and body composition also significantly improved (P < 0.001).

CONCLUSION

For patients with T2DM, compliance to real-life lifestyle interventions is good, and the interventions significantly improve metabolic indicators such as waist circumference, BMI, blood pressure, HbA1c, body composition, and motor function. Some patients are able to taper or discontinue hypoglycemic drugs.

Association between the tissue accumulation of advanced glycation end products and exercise capacity in cardiac rehabilitation patients

Background

Advanced glycation end products (AGEs) are associated with aging, diabetes mellitus (DM), and other chronic diseases. Recently, the accumulation of AGEs can be evaluated by skin autofluorescence (SAF). However, the relationship between SAF levels and exercise capacity in patients with cardiovascular disease (CVD) remains unclear. This study aimed to investigate the association between the tissue accumulation of AGEs and clinical characteristics, including exercise capacity, in patients with CVD.

Methods

We enrolled 319 consecutive CVD patients aged ≥40 years who underwent early phase II cardiac rehabilitation (CR) at our university hospital between November 2015 and September 2017. Patient background, clinical data, and the accumulation of AGEs assessed by SAF were recorded at the beginning of CR. Characteristics were compared between two patient groups divided according to the median SAF level (High SAF and Low SAF).

Results

The High SAF group was significantly older and exhibited a higher prevalence of DM than the Low SAF group. The sex ratio did not differ between the two groups. AGE levels showed significant negative correlations with peak oxygen uptake and ventilator efficiency (both P <  0.0001). Exercise capacity was significantly lower in the high SAF group than in the low SAF group, regardless of the presence or absence of DM (P <  0.05). A multivariate logistic regression analysis showed that SAF level was an independent factor associated with reduced exercise capacity (odds ratio 2.10; 95% confidence interval 1.13–4.05; P = 0.02).

Conclusion

High levels of tissue accumulated AGEs, as assessed by SAF, were significantly and independently associated with reduced exercise capacity. These data suggest that measuring the tissue accumulation of AGEs may be useful in patients who have undergone CR, irrespective of whether they have DM.

Both higher fitness level and higher current physical activity level may be required for intramyocellular lipid accumulation in non-athlete men

Accumulation of intramyocellular lipid (IMCL) is observed in individuals with insulin resistance as well as insulin-sensitive endurance athletes with high peak oxygen consumption (VO₂peak), which is called the athlete’s paradox. It remains unclear whether non-athletes with higher fitness levels have IMCL accumulation and higher insulin sensitivity in general. In this study, we investigated the association between IMCL accumulation and muscle insulin sensitivity (M-IS) in subjects with high or low VO₂peak. We studied 61 nonobese (BMI, 23 to 25 kg/m²), non-athlete Japanese men. We divided the subjects into four groups based on the median value of VO₂peak and IMCL in the soleus muscle. We evaluated M-IS using a two-step hyperinsulinemic-euglycemic clamp. Among subjects with higher VO₂peak (n = 32), half of those (n = 16) had lower IMCL levels. Both High-VO₂peak groups had higher M-IS than the Low-VO₂peak groups. On the other hand, M-IS was comparable between the High-VO₂peak/High-IMCL and High-VO₂peak/Low-IMCL groups, whereas the High-VO₂peak/High-IMCL group had IMCL levels that were twice as high as those in the High-VO₂peak/Low-IMCL group. On the other hand, the High-VO₂peak/High-IMCL group had significantly higher physical activity levels (approximately 1.8-fold) than the other three groups. In conclusion, in nonobese, non-athlete Japanese men, subjects with higher VO₂peak and higher IMCL had higher physical activity levels. IMCL accumulation is not associated with insulin resistance in individuals with higher or lower fitness levels.

Higher C-Peptide Level During Glucose Clamp Is Associated With Muscle Insulin Resistance in Nonobese Japanese Men

Context

Circulating C-peptide is generally suppressed by exogenous insulin infusion. However, steady-state serum C-peptide (SS_SC) levels during hyperinsulinemic-euglycemic clamp in obese subjects are higher than in healthy subjects, which may contribute to hyperinsulinemia to compensate for insulin resistance. Even in healthy subjects, interindividual variations in SS_SC levels are present; however, the characteristics of subjects with high SS_SC levels in those populations have not been fully elucidated.

Objective

To investigate the clinical parameters associated with interindividual variations in SS_SC levels in apparently healthy, nonobese Japanese men.

Design and Participants

We studied 49 nonobese (BMI < 25 kg/m²), healthy Japanese men. We evaluated SS_SC and insulin sensitivity using hyperinsulinemic-euglycemic clamp with tracer. Intrahepatic lipid (IHL) was measured using proton magnetic resonance spectroscopy.

Results

We divided subjects into high and low SS_SC groups based on the median SS_SC value and compared their clinical parameters. Compared with the low SS_SC group, the high SS_SC group had IHL accumulation, impaired muscle insulin sensitivity, reduced insulin clearance, and hyperinsulinemia during a 75-g oral glucose tolerance test (OGTT). All of these factors were significantly correlated with SS_SC.

Conclusions

In healthy, nonobese men, higher SS_SC was associated with impaired muscle insulin sensitivity, IHL accumulation, and hyperinsulinemia during OGTT. These findings suggest that higher endogenous insulin secretion during hyperinsulinemia, along with reduced insulin clearance, may be an early change to maintain metabolic status in the face of moderate muscle insulin resistance, even in healthy, nonobese men.

Relationship between the Kihon Checklist and the clinical parameters in patients who participated in cardiac rehabilitation

AIM

The Kihon Checklist is a useful screening tool for assessing frailty in older individuals. However, the clinical significance of the Kihon Checklist in cardiac rehabilitation patients remains unclear. The present study aimed to evaluate the relationship between the Kihon Checklist and the clinical parameters in patients who participated in cardiac rehabilitation.

METHODS

We enrolled 845 consecutive patients (584 men, mean age 71 years) who participated in cardiac rehabilitation at Juntendo University Hospital, Tokyo, Japan, between November 2015 and October 2017. The patients were divided into non-frailty (n = 287), pre-frailty (n = 270) and frailty (n = 288) groups according to their Kihon Checklist scores. Cardiopulmonary exercise testing was carried out in 302 patients.

RESULTS

The frailty group was older and had a higher prevalence of history of heart failure than the non-frailty group, although left ventricular ejection fraction did not differ significantly between groups. Nutritional index, trunk and limb muscle mass, lean body weight, and grip strength were significantly lower in the frailty and pre-frailty groups than those in the non-frailty group. In the cardiopulmonary exercise test, a stepwise significant decrease in peak oxygen uptake was observed across the three groups (non-frailty 17.2 ± 3.6, pre-frailty 16.0 ± 3.4, frailty 14.4 ± 3.5 mL/kg/min, P < 0.01). Multivariate regression analyses showed that the Kihon Checklist score was significantly and independently associated with peak oxygen uptake (r = -0.34, P < 0.0001).

CONCLUSIONS

The Kihon Checklist, which was associated with frailty and exercise tolerance, could be used as a clinical assessment method for patients who participated in cardiac rehabilitation. Geriatr Gerontol Int 2019; 19: 287-292.

May the force be with you: why resistance training is essential for subjects with type 2 diabetes mellitus without complications

Physical activity, together with diet and pharmacological therapy, represents one of the three cornerstones in type 2 diabetes mellitus treatment and care. The therapeutic appeal of regular physical activity stems from: (i) its non-pharmacological nature; (ii) its beneficial effects on the metabolic risk factors associated with diabetes complications; (iii) its low costs. Evidence accumulated in the last years suggests that aerobic training-endurance training-constitutes a safe modality of intervention, achievable, and effective in diabetes treatment, whenever it is not limited by comorbidities. Aerobic training exerts insulin-mimetic effects and has been shown to lower mortality risk too. Anaerobic, intense physical activity, such as that of strength or power sports disciplines, is not univocally recognized as safe and simple to realize, however, it is important in stimulating energy and glucose metabolism. According to recent evidence, high-intensity training may be prescribed even in the face of cardiovascular diseases, peripheral vascular disease, or osteoarthritis. Some studies have shown resistance training to be more efficient than aerobic exercise in improving glycemic control. This review explores the most up-to-date indications emerging from literature in support of the beneficial effects of strength stimulation and resistance training in patients with type 2 diabetes without complications.

Detection of glucose metabolism disorders in coronary patients enrolled in cardiac rehabilitation: Is glycated haemoglobin useful? Data from the prospective REHABDIAB study

Introduction

Diabetes and pre-diabetes are highly prevalent in patients with a history of acute coronary syndrome. This is why screening for glucose metabolism disorders is recommended in patients following an acute coronary syndrome. The aim of our study was to determine whether glycated haemoglobin alone compared with the oral glucose tolerance test could allow effective screening for glucose metabolism disorders in acute coronary syndrome patients undergoing cardiac rehabilitation.

Patients and methods

Among 347 patients with a recent history of acute coronary syndrome enrolled in our cardiac rehabilitation centre, 267 patients without previously known diabetes were recruited for this prospective study with performance of both oral glucose tolerance test and glycated haemoglobin measurement. The patients were divided into three groups: newly diagnosed diabetes mellitus, pre-diabetes and normoglycaemia according to the oral glucose tolerance test and glycated haemoglobin results. The results obtained with glycated haemoglobin were compared with those obtained with the oral glucose tolerance test, considered as the reference.

Results

For the diagnosis of diabetes, glycated haemoglobin had a sensitivity of 72% and a specificity of 100%. Positive and negative predictive values were high at 100% and 96%, respectively. However, for the diagnosis of pre-diabetes the sensitivity of glycated haemoglobin was low at 64% as were the specificity (53%) and the positive predictive values (37%). Glycated haemoglobin overdiagnosed pre-diabetes (52% vs 30%, p < 0.0001). For the diagnosis of normoglycaemia, the sensitivity of glycated haemoglobin was also low (48%).

Conclusion

According to our study, glycated haemoglobin has low sensitivity and specificity for the detection of pre-diabetes in patients with coronary disease enrolled in cardiac rehabilitation, and glycated haemoglobin over-diagnoses pre-diabetes in comparison with the oral glucose tolerance test.

Correlates of insulin clearance in apparently healthy non-obese Japanese men

Hyperinsulinemia observed in obese subject is caused at least in part by low metabolic clearance rate of insulin (MCRI). However, the determinants of MCRI in non-obese subjects are not fully understood. To investigate the correlates of MCRI in healthy non-obese men (BMI <25 kg/m2), we studied 49 non-obese Japanese men free of cardiometabolic risk factors. Using a 2-step hyperinsulinemic euglycemic clamp, we evaluated MCRI and insulin sensitivity. We also calculated the rate of glucose disappearance (Rd) during the clamp and muscle insulin sensitivity was defined as Rd/steady state serum insulin (SSSI) at the second step. Based on the median value of MCRI, the subjects were divided into the low- and high-MCRI groups. Subjects of the low-MCRI group had significant impairment of muscle insulin sensitivity, although Rd levels were comparable between the two groups, probably due to elevated SSSI in the low-MCRI group. Subjects of the low-MCRI group had higher total body fat content and lower VO2peak and showed no deterioration of cardiometabolic risk factors. Our results suggest that low MCRI may be early change to maintain glucose uptake and metabolic status in the face of slight impairment of muscle insulin sensitivity caused by increased adiposity and lower fitness level.

Exercise as Medicine: Key Concepts in Discussing Physical Activity with Patients who have Type 2 Diabetes

People with type 2 diabetes stand to benefit substantially from being physically active. Practice guidelines consistently recommend that people with diabetes obtain at least 150 minutes of moderate to vigorous aerobic exercise per week. Although the message of 150 minutes per week is important, there are several other key messages regarding physical activity that may not be communicated as often or as clearly. This article gives an overview of the importance of resistance training, the dose-response relationship between physical activity and health outcomes, and the emerging evidence concerning the role of sedentary behavior in people with type 2 diabetes. This article provides valuable content for healthcare providers that will help to inform their discussions about physical activity with patients who have type 2 diabetes.

Moving beyond cardio: the value of resistance training, balance training, and other forms of exercise in the management of diabetes

IN BRIEF Traditionally, aerobic training has been a central focus of exercise promotion for diabetes management. However, people with diabetes have much to gain from other forms of exercise. This article reviews the evidence and recommendations on resistance, balance, and flexibility training, as well as other, less traditional, forms of exercise such as yoga and Tai Chi.

Evaluation of myocardial triglyceride accumulation assessed on 1H-magnetic resonance spectroscopy in apparently healthy Japanese subjects

OBJECTIVE

Proton magnetic resonance spectroscopy ((1)H-MRS) enables the clinician to noninvasively assess the amount of ectopic fat in the liver, skeletal muscle and myocardium. Recent studies have reported that the myocardial triglyceride (TG) content is associated with aging, metabolic disorders and cardiac dysfunction. However, the clinical usefulness of myocardial TG measurements in Japanese subjects has not been fully investigated.

METHODS

The myocardial TG content was evaluated using (1)H-MRS in 37 apparently healthy Japanese subjects, and the left ventricular function was measured on cardiac magnetic resonance imaging (MRI). Blood pressure, body composition and biochemical markers were measured in a fasting state, and cardiopulmonary exercise testing (CPX) was performed to evaluate exercise capacity.

RESULTS

The mean myocardial TG content was 0.85±0.40%. The myocardial TG content was significantly associated with the percent body fat (r=0.39), serum triglyceride level (r=0.40), estimated glomerular filtration rate (r=-0.37), anaerobic threshold (r=-0.36), maximal load of CPX (r=0.39), left ventricular end-diastolic volume (r=-0.41) and left ventricular end-systolic volume (LVESV) (r=-0.51) (all: p<0.05). In a multivariate analysis, the LVESV was found to be an independent factor of the myocardial TG content.

CONCLUSION

(1)H-MRS may be useful for assessing the associations between the myocardial TG content and various clinical parameters, including those reflecting obesity, metabolic disorders, cardiac morphology and exercise capacity, noninvasively, even in Japanese subjects.

Relationship between muscle mass and muscle strength, and the impact of comorbidities: a population-based, cross-sectional study of older adults in the United States

Background

Loss of muscle mass and muscle strength are natural consequences of the aging process, accompanied by an increased prevalence of chronic health conditions. Research suggests that in the elderly, the presence of comorbidities may impact the muscle mass/strength relationship. The objectives of this study were to characterize the muscle mass/strength relationship in older adults in the USA and to examine the impact of a variety of comorbidities on this relationship.

Methods

Data were obtained from the National Health and Nutrition Examination Survey 1999–2002 databases. Subjects aged 50 years and older were included in the present study. Muscle mass was assessed by height-adjusted appendicular skeleton muscle mass (aASM) in kg/m², as measured by dual-energy x-ray absorptiometry. Muscle strength was assessed via isokinetic quadriceps strength (IQS) in newton as measured by a dynamometer. The relationship between aASM and IQS was assessed adjusting for age and gender. The effects of a variety of comorbidities on IQS and/or on the relationship between IQS and aASM were assessed using multiple regression models.

Results

This study included 2,647 individuals, with a mean age of 62.6 years and 52.9% of whom were female. The mean (SE) aASM (kg/m²) was 7.3 (0.04), and the mean (SE) IQS (newton) was 365.0 (3.00). After adjusting for age and gender, the correlation coefficient between aASM and IQS was 0.365 (P < 0.001). Diabetes, coronary heart disease/congestive heart failure (CHD/CHF), and vision problems were significant predictors of lower muscle strength (P < 0.05) in the multiple regression models that adjusted for age, gender, and aASM, and obesity significantly modified the relationship between aASM and IQS (P < 0.05).

Conclusions

Among individuals aged 50 and older in the US, muscle mass and muscle strength are positively correlated, independent of the associations of age and gender with muscle mass and strength. A variety of comorbid medical conditions serve as independent predictors of lower muscle strength (e.g., diabetes, CHD/CHF, vision problems) and/or modify the relationship between muscle mass and muscle strength (e.g., obesity).

Sex differentiation with regard to coronary artery disease

Coronary artery disease was considered a male disease for many years. However, nowadays, coronary artery disease constitutes the leading cause of death in women, although there are a lot of gender-related differences regarding the presentation of acute myocardial infarction, its diagnosis, its treatment, short- and long-term mortality rates, and post-acute myocardial infarction complications. Generally, women have smaller and stiffer hearts and cardiac vessels, suffering a greater extent of atherosclerosis and endothelial and smooth muscle dysfunction. They are usually older than men and they have more comorbidities such as hypertension, renal impairment, and diabetes mellitus. Moreover, female coronary artery disease, the diagnosis of which is more complicated due to more false negative results of some diagnostic methods in women, is more often presented with atypical symptoms and women's symptoms of typical or atypical angina are more severe. Furthermore, women delay significantly more in seeking care and they are more frequently undertreated. Finally, women are associated with generally poorer in-hospital and long-term prognosis having almost two-fold higher early mortality and they are more prone to complications such as bleeding complications, shock, and heart failure, as well as to post-myocardial infarction depression and poorer physical function and mental health. In this review, we discuss these sex-related differences according to current literature.

Association between myocardial triglyceride content and cardiac function in healthy subjects and endurance athletes

Ectopic fat accumulation plays important roles in various metabolic disorders and cardiovascular diseases. Recent studies reported that myocardial triglyceride (TG) content measured by proton magnetic resonance spectroscopy (¹H-MRS) is associated with aging, diabetes mellitus, and cardiac dysfunction. However, myocardial TG content in athletes has not yet been investigated. We performed ¹H-MRS and cardiac magnetic resonance imaging in 10 male endurance athletes and 15 healthy male controls. Serum markers and other clinical parameters including arterial stiffness were measured. Cardiopulmonary exercise testing was also performed. There were no significant differences in clinical characteristics including age, anthropometric parameters, blood test results, or arterial stiffness between the two groups. Peak oxygen uptakes, end–diastolic volume (EDV), end–systolic volume (ESV), left ventricular (LV) mass, peak ejection rates and peak filling rates were significantly higher in the athlete group than in the control group (all P<0.02). Myocardial TG content was significantly lower in the athlete group than in the control group (0.60±0.20 vs. 0.89±0.41%, P<0.05). Myocardial TG content was negatively correlated with EDV (r = −0.47), ESV (r = −0.64), LV mass (r = −0.44), and epicardial fat volume (r = 0.47) (all P<0.05). In conclusion, lower levels of myocardial TG content were observed in endurance athletes and were associated with morphological changes related to physiological LV alteration in athletes, suggesting that metabolic imaging for measurement of myocardial TG content by ¹H-MRS may be a useful technique for noninvasively assessing the “athlete’s heart”.

Effect of cardiac rehabilitation on muscle mass, muscle strength, and exercise tolerance in diabetic patients after coronary artery bypass grafting

BACKGROUND

The effects of cardiac rehabilitation (CR) on muscle mass, muscle strength, and exercise tolerance in patients with diabetes mellitus (DM) who received CR after coronary artery bypass grafting (CABG) have not been fully elucidated.

METHODS

We enrolled 78 consecutive patients who completed a supervised CR for 6 months after CABG (DM group, n=37; non-DM group, n=41). We measured mid-upper arm muscle area (MAMA), handgrip power (HGP), muscle strength of the knee extensor (Ext) and flexor (Flex), and exercise tolerance at the beginning and end of CR.

RESULTS

No significant differences in confounding factors, including age, gender, ejection fraction, or number of CR sessions, were observed between the two groups. At the beginning of CR, the levels of Ext muscle strength and peak VO2 were significantly lower in the DM group than in the non-DM group. At the end of CR, significant improvement in the levels of muscle strength, HGP, and exercise tolerance was observed in both groups. However, the levels of Ext muscle strength, HGP, peak VO2, thigh circumference, and MAMA were significantly lower in the DM group than in the non-DM group. In addition, no significant improvement in thigh circumference and MAMA was observed in the DM group. At the end of CR, the levels of thigh circumference and MAMA correlated with Ext and Flex muscle strength as well as with HGP. Percent changes in the levels of Ext muscle strength were significantly correlated with those of MAMA and hemoglobin A1c.

CONCLUSIONS

These data suggest that improvement in muscle strength may be influenced by changes in muscle mass and high glucose levels in DM patients undergoing CR after CABG. A CR program, including muscle mass intervention and blood glucose control, may improve deterioration in exercise tolerance in DM patients after CABG.

Risk factors for a 6-year decline in physical disability and functional limitations among elderly people with type 2 diabetes in the Japanese Elderly Diabetes Intervention Trial

AIM

Type 2 diabetes increases the risk of disability. The purpose of this study was to clarify the explanatory factors for disability in Japanese diabetic elderly.

METHODS

The 6-year decline in physical disability and functional limitations was investigated among 317 elderly people with type 2 diabetes recruited in a large-scale prospective study of the Japanese Elderly Diabetes Intervention Trial. Information about diabetes, blood examinations and complications was obtained, and basic activities of daily living (ADL) and instrumental ADL (IADL) were assessed by total score of the Barthel index and the Tokyo Metropolitan Institute of Gerontology Index of Competence, respectively.

RESULTS

After 6 years of follow up, 13.6% of patients had developed a new ADL disability and 38.3% had developed a new functional impairment. In the 65-74 years age group, basic ADL decreased only in males, whereas females became functionally impaired. In the 75-84 years age group, basic and IADL decreased in both males and females. Older age and metabolic syndrome were prognostic for impairment of basic ADL, whereas baseline IADL problems, lower cognitive function, physical inactivity and insulin therapy were significant predictors of a future decline in the IADL.

CONCLUSION

This study identified several factors predicting the future decline of basic ADL and IADL in diabetic elderly patients, and provided a conceptual framework that might help to clarify the pathways leading to disability. Because the specific causes of each functional problem are modifiable, comprehensive treatment and care are needed to allow Japanese diabetic elderly patients to have more favorable living conditions.