A six-month exercise intervention in subclinical diabetic heart disease: Effects on exercise capacity, autonomic and myocardial function

Abstract

A six-month exercise intervention in subclinical diabetic heart disease: effects on exercise capacity, autonomic and myocardial function, Metabolism (2014Metabolism ( ), doi: 10.1016Metabolism ( /j.metabol.2014 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPTObjective. Autonomic dysfunction may contribute to the etiology and exercise intolerance of subclinical diabetic heart disease. This study sought the efficacy of exercise training for improvement of peak oxygen uptake (VO 2peak ) and cardiac autonomic function in type 2 diabetic patients with non-ischemic subclinical left-ventricular (LV) dysfunction.Materials/Methods. Forty-nine type 2 diabetic patients with early diastolic tissue Doppler velocity >1 standard deviation below the age-based mean entered an exercise intervention (n=24) or usual care (n=25) for 6-months (controlled, pre-/post-design). Co-primary endpoints were treadmill VO 2peak and 5-minute heart-rate variability (by the coefficient of variation of normal RR intervals [CVNN]). Autonomic function was additionally assessed by resting heart-rate (for sympathovagal balance estimation), baroreflex sensitivity, cardiac reflexes, and exercise/recovery heart-rate profiles. Echocardiography was performed for LV function (systolic/diastolic tissue velocities, myocardial deformation) and myocardial fibrosis (calibrated integrated backscatter).Results. VO 2peak increased by 11% during the exercise intervention (p=0.001 vs. −1% in controls), but CVNN did not change (p=0.23). Reduction of resting heart-rate in the intervention group (p<0.05) was associated with an improvement in the secondary endpoint of heart-rate variability total spectral power (p<0.05). However, baroreflex sensitivity, cardiac reflexes, and exercise/recovery heart-rate profiles showed no significant benefit. No effects on LV function were observed despite favorable reduction of calibrated integrated backscatter in the intervention group (p<0.05).Conclusions. The exercise intolerance of subclinical diabetic heart disease was amenable to improvement by exercise training. Despite a reduction in resting heart-rate and potential attenuation of myocardial fibrosis, no other cardiac autonomic or LV functional adaptations were detected. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT

Influence of the Exercise on Autonomic Nervous System in Diabetics: A Literature Review

“…Regarding to the effects of physical training in type 2 DM with ischemic subclinical left ventricle dysfunction it was evaluated after a program of six months and there was increase in global HRV (TP and SDNN) but changes were not found in the parasympathetic modulation (RMSSD and HFms²). Also, there was improvement on sympathetic-vagal balance (RR mean), showing a decrease of resting HR, which implies a relative bradycardia induced by exercise [21] . Kanaley et al [22] performed an aerobic training for obese individuals with and without type 2 DM and found increase on global HRV and increase on parasympathetic modulation (HF) in just obese individuals but the same result was not found in obese individuals with type 2 DM.…”

“…GE: 5 minutes warmup, 30 minutes aerobic exercise and 10 minutes relaxation Regular physical exercise increased HRV in diabetic patients with and without hypertension, being higher b e n e f i t s i n t h o s e w h o hypertension Sacre et al 2014 [21] 47 individuals with DM2 and subclinical ventricular nonischemic dysfunction. GE (n = 22); GC (n = 25) R R m e a n , S D N N , RMSSD, PT, LF, HF, LF/ HF ratio Duration: 6 months.…”

“…The authors suggest that a longer period of physical training could also lead to significant improvements at rest. The different responses observed in autonomic modulation induced by physical training in individuals with DM may be related to the different prescriptions used (e.g., type of exercise, frequency, intensity) [21] . Then, the above studies included different exercise protocols, and although most studies contained aerobic training, they changed regarding to the type of exercise, frequency and intensity, which may have influenced the results.…”

Effects of Resistance Training on Autonomic Nervous Function in Older Individuals

“…Although they did not evaluate the isolated effects of RT, two studies assessed the effects of cardiac rehabilitation on autonomic control in patients with heart failure [45] and the effects of combined aerobic/resistance training in patients with type 2 diabetes [46]. RiccaMallada et al [45] evaluated the effects of cardiac rehabilitation on deceleration and acceleration capacity, new indicators of autonomic control of the cardiovascular system [47], in patients with heart failure with reduced left ventricular ejection fraction.…”

“…Cardiac rehabilitation, including circuit RT, could improve ANF in patients with chronic heart failure. Sacre et al [46] investigated the efficacy of exercise training to improve cardiac autonomic function in type 2 diabetic patients with non-ischemic subclinical left ventricular dysfunction. Patients with valvular disease, ischemic heart disease, cardiovascular disease, psychiatric disorder, symptomatic macro-or micro-vascular complications, and low ejection fraction (<50%) were excluded.…”