Endurance training improves post-exercise cardiac autonomic modulation in obese women with and without type 2 diabetes

Exercise Effects on Autonomic Nervous System Activity in Type 2 Diabetes Mellitus Patients over Time: A Meta-Regression Study

BACKGROUND

Diabetic autonomic neuropathy is a common complication of type 2 diabetes mellitus (T2DM), especially in patients with long-term, poorly controlled diabetes. This study investigates the effects of exercise on autonomic nervous system activity in T2DM patients over time.

METHODS

A literature review using MEDLINE, Embase, Cochrane Library, Scopus, and PubMed identified studies assessed via heart rate variability. Papers were categorized into three groups: immediate effects (within 60 min), short-term effects (2-3 months), and long-term effects (over 4 months).

RESULTS

Nine articles with 161 T2DM patients were included in the meta-analysis. RMSSD changes after exercise were -4.3 (p = 0.227), 8.14 (p < 0.001), and 4.17 (p = 0.002) for the immediate, short-term, and long-term groups, respectively. LF/HF ratio changes were 0.21 (p = 0.264), -3.04 (p = 0.102), and -0.05 (p = 0.006) for the respective groups. Meta-regression indicated age, male gender, and exercise duration were associated with increased RMSSD, with coefficients of 2.36 (p = 0.001), 13.76 (p = 0.008), and 1.50 (p = 0.007), respectively. Age positively correlated with the LF/HF ratio, with a coefficient of 0.049 (p = 0.048).

CONCLUSIONS

Regular exercise (≥3 times per week) for over 2 months increases parasympathetic activity in T2DM patients, while sympathetic activity decreases significantly after 4 months. Further study is needed to validate these findings.

Post-acute exercise cardiovagal modulation in older male adults with and without type 2 diabetes

PURPOSE

We examined heart rate variability (HRV) and baroreflex sensitivity (BRS) disease- and age-related response at 10-and 60-min after an acute high-intensity interval (HIIE) and moderate continuous exercise (MICE) in older adults with and without type 2 diabetes mellitus (T2DM) and healthy young adults.

METHODS

Twelve older male adults with (57-84 years) and without T2DM (57-76 years) and 12 healthy young male adults (20-40 years) completed an isocaloric acute bout of HIIE, MICE, and a non-exercise condition in a randomized order. Time and Wavelets-derived frequency domain indices of HRV and BRS were obtained in a supine position and offline over 2-min time-bins using Matlab.

RESULTS

HIIE but not MICE reduced natural logarithm root mean square of successive differences (Ln-RMSSD) (d = - 0.85; 95% CI - 1.15 to - 0.55 ms, p < 0.001), Ln-high-frequency power (d = - 1.60; 95% CI - 2.24 to - 0.97 ms2; p < 0.001), and BRS (d = - 6.32; 95% CI - 9.35 to - 3.29 ms/mmHg, p < 0.001) in adults without T2DM (averaged over young and older adults without T2DM), returning to baseline 60 min into recovery. These indices remained unchanged in older adults with T2DM after HIIE and MICE. Older adults with T2DM had lower resting Ln-RMSSD and BRS than aged-matched controls (Ln-RMSSD, d = - 0.71, 95% CI - 1.16 to - 0.262 ms, p = 0.001; BRS d = - 3.83 ms/mmHg), 95% CI - 6.90 to - 0.76, p = 0.01).

CONCLUSIONS

Cardiovagal modulation following acute aerobic exercise is intensity-dependent only in adults without T2DM, and appears age-independent. These findings provide evidence of cardiac autonomic impairments in older adults with T2DM at rest and following aerobic exercise.

Effects of Vibration Training on Weight Loss and Heart Rate Variability in the Obese Female College Students

Objective

The present study examined the effects of a 12-week whole-body vibration training (WBVT) regimen on heart rate variability (HRV) and body composition in the obese female college students.

Methods

Participants were assigned to either the WBVT (n = 17) or obese control group (n = 19). The students in the WBVT group conducted a 12-week (5 times per week and 30 min per time) exercise protocols (30 to 40 Hz of frequency and 4 mm of amplitude), and the obese control group did not perform regular physical training during 12 weeks of study. Then, body composition (body weight, BMI, body fat, body fat percentage; trunk fat mass, muscle mass, MM) and HRV (time domain and frequency domain index) were measured in all subjects before and after WBVT intervention.

Results

(1) After 12-week WBVT intervention, body fat mass, trunk fat mass, and body fat percentage significantly decreased and muscle mass increased in the WBVT group (P < 0.01, respectively); there was no significant change in body weight and BMI (P > 0.05, respectively). (2) After 12-week WBVT intervention, LFn, LF/HF, and HR significantly decreased (P < 0.05, P < 0.01), R-R interval and RMSSD significantly increased (P < 0.01, respectively), and there was no significant difference in HFn (P > 0.05). Nevertheless, there was no significant change before and after the test in body composition and HRV in the obese control group (P > 0.05, respectively). (3) After 12-week WBVT intervention, compared with the obese control group, body fat mass, body fat percentage, trunk fat mass, and LF/HF significantly decreased (P < 0.05, P < 0.01), muscle mass, and RMSSD increased (P < 0.05) in the WBVT group; but there were no significant difference in other indicators (P > 0.05) between the obese control group and WBVT group. (4) The reduction of body fat percentage before and after the WBVT intervention are positively correlated with the reduction in the LFn and LF/HF (r = 0.542, r = 0.504; P < 0.05, respectively) and negatively correlated with the increase in the RMSSD (r = −0.514, P < 0.05), and the reduction of trunk fat mass are positively correlated with the reduction in the LF/HF (r = 0.540, P < 0.05).

Conclusion

The results indicate that WBVT improves HRV and body composition in obese female college students, and the reduction in body fat percentage and trunk fat mass are associated with a shift in cardiac autonomic regulation towards vagal dominance and improve sympathetic-vagus balance after WBVT intervention. In conclusion, WBVT may be a feasible treatment to improve cardiac autonomic function and body composition.

The effect of a home-based coaching program on heart rate variability in subacute stroke patients: a randomized controlled trial

Autonomic imbalance in stroke is characterized by increased sympathetic activity and reduced vagal nerve activity. Physical activity could be a strategy to counteract autonomic control impairments after a stroke. The aim of the study was to evaluate the effect on heart rate variability of a 6-month coaching program in a home setting in subacute stroke patients. Eighty-four stroke patients participated in the study. They were randomly assigned to the experimental group or the control group. The intervention was a coaching program, consisting of physical activity, home visits and a weekly phone call. Patients were evaluated after hospital discharge (T0) and at the end of the 6-month period (T1). Heart rate variability measures were recorded in the supine and orthostatic positions. Time and frequency domain values were treated using Kubios. Distance on 6 minutes walking test (6MWT), Barthel and motricity index and modified functional ambulation categories were evaluated. No effects were found on time and frequency domain values in the supine and orthostatic positions in either group. Walking distance on 6MWT increased significantly between T0 and T1 in experimental group (377 ± 141-448 ± 140 m; P < 0.02) with no effects in control group (373.6 ± 150.6-394.6 ± 176.4 m). No other functional effects were found. A coaching program in a home setting had no effect on heart rate variability, probably due to time of recovery and exercise intensity. Future research is needed to understand the lack of changes in heart rate variability by physical activity in subacute stroke patients.

Combined effects of angiotensin receptor blocker use and physical training in hypertensive men

PURPOSE

Pharmacological (angiotensin II receptor type 1 receptor blocker use) and non-pharmacological treatment (physical aerobic exercise) are important strategies to reduces blood pressure and control arterial hypertension; however, only few clinical studies have evaluated their combined effects on autonomic cardiovascular control. Therefore, we investigated the effect of a combination intervention that involved losartan administration and physical aerobic training on autonomic cardiovascular control.

METHODS

Thirty-two men (aged 40 to 60 years) were assigned into two groups: normotensive group, without any pharmacological treatment (NG, N = 16), or hypertensive group, with losartan administration (HG, N = 16). They underwent a physical aerobic training for 16 weeks, thrice a week. Hemodynamic parameters, heart rate variability (HRV), blood pressure variability, and spontaneous baroreflex sensitivity (BRS) were measured before and after training.

RESULTS

Before training, both the groups showed similar values of hemodynamic parameters. However, the HG showed decreased BRS and HRV, characterized by reduction in sympathetic (p = .02) and vagal (p < .001) modulation. After training, the NG exhibited decreased heart rate (HR) at rest (p < .001), whereas the HG showed decreased HR at rest (p < .001) and blood pressure (BP) (p = .001). The HG showed decreased sympathetic modulation (p = .02) and increased BRS (p < .001) and vagal modulation (p < .001), but HRV (p < .001) and BRS gain (p < .001) remained significantly lower when compared to the NG.

CONCLUSIONS

Physical aerobic training was essential to improve the BRS and HRV cardiac autonomic modulation in the HG. However, it was not sufficient to normalize the analyzed autonomic parameters.

Habitual aerobic exercise in healthy postmenopausal women does not augment basal cardiac autonomic activity yet modulates autonomic-metabolic interactions

OBJECTIVES

The aim of the present study was to examine the effects of habitual exercise training and metabolic health on basal cardiac autonomic function and cardiac autonomic recovery after exercise in healthy postmenopausal women (PMW).

METHODS

Habitually aerobically trained PMW (PMW-tr; 56 ± 1y; n = 11), and untrained PMW (PMW-un; 57 ± 1y; n = 13) and premenopausal women (PreM; ages 26 ± 1y; n = 14) were studied. Cardiac autonomic function, assessed using heart rate variability (HRV), was measured before and one hour after 45-minutes of moderate-intensity exercise (60% VO2peak). Fast Fourier frequency domain measures of high (HF; 0.15 Hz-0.4 Hz), low (LF; 0.04 Hz-0.15 Hz), very low (VLF; 0.01 Hz-0.04 Hz), and Total (VLF+LF+HF) HRV were assessed. Serum estradiol, insulin, and glucose were determined, and HOMA-IR, an index of insulin resistance, was calculated.

RESULTS

In PMW groups, body composition and serum markers did not differ (P>0.05). Pre-exercise, heart rate was lower (P<0.05) in PMW-tr than PMW-un, yet HRV did not differ (P>0.05). In PMW-tr only, HF was inversely associated (P<0.05) with insulin (r = -0.738) and HOMA-IR (r = -0.758). In PreM, HRV was higher than PMW (P<0.05) and was positively correlated with estradiol (P<0.05). Postexercise, HRV was decreased within all groups (P<0.05) yet remained higher in PreM (P<0.05), and similar (P>0.05) between PMW.

CONCLUSION

Basal and postexercise HRV does not differ between habitually aerobically trained and untrained PMW. However, greater insulin sensitivity was associated with higher cardiac parasympathetic tone in trained PMW only. Exercise training may favorably modulate cardiac autonomic-metabolic interactions in PMW.

Diagnostic Tools, Biomarkers, and Treatments in Diabetic polyneuropathy and Cardiovascular Autonomic Neuropathy

The various manifestations of diabetic neuropathy, including distal symmetric sensorimotor polyneuropathy (DSPN) and cardiovascular autonomic neuropathy (CAN), are among the most prevalent chronic complications of diabetes. Major clinical complications of diabetic neuropathies, such as neuropathic pain, chronic foot ulcers, and orthostatic hypotension, are associated with considerable morbidity, increased mortality, and diminished quality of life. Despite the substantial individual and socioeconomic burden, the strategies to diagnose and treat diabetic neuropathies remain insufficient. This review provides an overview of the current clinical aspects and recent advances in exploring local and systemic biomarkers of both DSPN and CAN assessed in human studies (such as biomarkers of inflammation and oxidative stress) for better understanding of the underlying pathophysiology and for improving early detection. Current therapeutic options for DSPN are (I) causal treatment, including lifestyle modification, optimal glycemic control, and multifactorial risk intervention, (II) pharmacotherapy derived from pathogenetic concepts, and (III) analgesic treatment against neuropathic pain. Recent advances in each category are discussed, including non-pharmacological approaches, such as electrical stimulation. Finally, the current therapeutic options for cardiovascular autonomic complications are provided. These insights should contribute to a broader understanding of the various manifestations of diabetic neuropathies from both the research and clinical perspectives.

Forecast of ameliorating effect of dietary flavonol consumption in white tea with or without aerobic training on type 2 diabetes (T2D) in females

BACKGROUND AND AIMS

Diabetes Mellitus (D.M.) is a chronic metabolic disease characterized by hyperglycemia due to insufficient or inefficient insulin secretory response that has become a widespread epidemic primarily due to the increasing prevalence and incidence of type 2 diabetes. Phytochemicals such as flavonoids and regular physical activity have recently attracted attention to developing new anti-diabetic drugs or alternative therapy to control diabetes. The aim of this study was to compare effects of dietary Flavonol consumption in white tea, with or without aerobic training, among patients with type 2 diabetes mellitus as a randomized trial.

METHODS

49 women with T2D were randomly assigned into groups including control, white tea, aerobic training, and aerobic training + white tea. The interventions were carried out for six months. Weight, Body Mass Index (BMI), body Fat, peak oxygen consumption (VO2Max), and Blood Pressure were evaluated at both the first and last days of the research period. Blood samples were withdrawn on the same days via venipuncture to test blood glucose, insulin, low-density lipoprotein (LDL), high-density lipoprotein (HDL), cholesterol, and triglycerides (T.G.).

RESULTS

Characteristics analysis showed significant improvements in treated groups. In addition, glucose, insulin, LDL, Cholesterol, and T.G. were significantly reduced while HDL was remarkably increased in treated groups compared to pre-experiment values or the diabetic control group.

CONCLUSION

Collectively, white tea combined with aerobic training favorably affects glycemic parameters, lipid profile, blood pressure, and VO2Max in six months in women with T2D. Registered under Clinical Trials.gov Identifier no. NCT00123456.

Effect of exercise training on heart rate variability in type 2 diabetes mellitus patients: A systematic review and meta-analysis

Background

Cardiac autonomic neuropathy is a common complication of type 2 diabetes mellitus (T2DM), that can be measured through heart rate variability (HRV)–known to be decreased in T2DM. Physical exercise can improve HRV in healthy population, however results are under debate in T2DM. We conducted a systemic review and meta-analysis to assess the effects of physical exercise on HRV in T2DM patients.

Method

PubMed, Cochrane, Embase, and ScienceDirect databases were searched for all studies reporting HRV parameters in T2DM patients before and after exercise training, until September 20th 2020, without limitation to specific years. We conducted random-effects meta-analysis stratified by type of exercise for each of the HRV parameters: RR–intervals (or Normal to Normal intervals–NN), standard deviation of RR intervals (SDNN), percentage of adjacent NN intervals varying by more than 50 milliseconds (pNN50), root mean square of successive RR-intervals differences (RMSSD), total power, Low Frequency (LF), High Frequency (HF) and LF/HF ratio. Sensitivity analyses were computed on studies with the highest quality.

Results

We included 21 studies (9 were randomized) for a total of 523 T2DM patients: 472 had an exercise training and 151 were controls (no exercise). Intervention was endurance (14 studies), resistance (2 studies), endurance combined with resistance (4 studies), and high intensity interval training (HIIT) (4 studies). After exercise training, all HRV parameters improved i.e. an increase in SDNN (effect size = 0.59, 95%CI 0.26 to 0.93), RMSSD (0.62, 0.28 to 0.95), pNN50 (0.62, 0.23 to 1.00), HF (0.58, -0.16 to 0.99), and a decrease in LF (-0.37, -0.69 to -0.05) and LF/HF (-0.52, -0.79 to -0.24). There were no changes in controls. Stratification by type of exercise showed an improvement in most HRV parameters (SDNN, RMSSD, pNN50, LF, HF, LF/HF) after endurance training, whereas mostly LF/HF was improved after both resistance training and HIIT. Supervised training improved most HRV parameters. Duration and frequency of training did not influence the benefits on HRV.

Conclusion

Exercise training improved HRV parameters in T2DM patients which may reflect an improvement in the activity of the autonomic nervous system. The level of proof is the highest for endurance training. Supervised training seemed beneficial.

Effect of Moderate- Versus High-Intensity Interval Exercise Training on Heart Rate Variability Parameters in Inactive Latin-American Adults: A Randomized Clinical Trial

Ramírez-Vélez, R, Tordecilla-Sanders, A, Téllez-T, LA, Camelo-Prieto, D, Hernández-Quiñonez, PA, Correa-Bautista, JE, Garcia-Hermoso, A, Ramírez-Campillo, R, and Izquierdo, M. Effect of moderate- versus high-intensity interval exercise training on heart rate variability parameters in inactive Latin-American adults: a randomized clinical trial. J Strength Cond Res 34(12): 3403-3415, 2020-We investigated the effect of moderate versus high-intensity interval exercise training on the heart rate variability (HRV) indices in physically inactive adults. Twenty inactive adults were randomly allocated to receive either moderate-intensity training (MCT group) or high-intensity interval training (HIT group). The MCT group performed aerobic training at an intensity of 55-75%, which consisted of walking on a treadmill at 60-80% of the maximum heart rate (HRmax) until the expenditure of 300 kcal. The HIT group ran on a treadmill for 4 minutes at 85-95% peak HRmax and had a recovery of 4 minutes at 65% peak HRmax until the expenditure of 300 kcal. Supine resting HRV indices (time domain: SDNN = SD of normal-to-normal intervals; rMSSD = root mean square successive difference of R-R intervals and frequency domain: HFLn = high-frequency spectral power; LF = low-frequency spectral power and HF/LF ratio) were measured at baseline and 12 weeks thereafter. The SDNN changes were 3.4 (8.9) milliseconds in the MCT group and 29.1 (7.6) milliseconds in the HIT group {difference between groups 32.6 (95% confidence interval, 24.9 to 40.4 [p = 0.01])}. The LF/HFLn ratio changes were 0.19 (0.03) milliseconds in the MCT group and 0.13 (0.01) milliseconds in the HIT group (p between groups = 0.016). No significant group differences were observed for the rMSSD, HF, and LF parameters. In inactive adults, this study showed that a 12-week HIT training program could increase short-term HRV, mostly in vagally mediated indices such as SDNN and HF/LFLn ratio power. Trial registration. ClinicalTrials.gov NCT02738385 https://clinicaltrials.gov/ct2/show/NCT01796275, registered on March 23, 2016.

Walking for hypertension

BACKGROUND

Increased physical activity has been recommended as an important lifestyle modification for the prevention and control of hypertension. Walking is a low-cost form of physical activity and one which most people can do. Studies testing the effect of walking on blood pressure have revealed inconsistent findings.

OBJECTIVES

To determine the effect of walking as a physical activity intervention on blood pressure and heart rate.

SEARCH METHODS

We searched the following databases up to March 2020: the Cochrane Hypertension Specialised Register, CENTRAL (2020, Issue 2), Ovid MEDLINE, Ovid Embase, CINAHL, PsycINFO, SPORTDiscus, PEDro, the WHO International Clinical Trials Registry Platform, and ClinicalTrials.gov. We also searched the following Chinese databases up to May 2020: Index to Taiwan Periodical Literature System; National Digital Library of Theses and Dissertation in Taiwan; China National Knowledge Infrastructure (CNKI) Journals, Theses & Dissertations; and Wanfang Medical Online. We contacted authors of relevant papers regarding further published and unpublished work. The searches had no language restrictions.

SELECTION CRITERIA

Randomised controlled trials of participants, aged 16 years and over, which evaluated the effects of a walking intervention compared to non-intervention control on blood pressure and heart rate were included.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Where data were not available in the published reports, we contacted authors. Pooled results for blood pressure and heart rate were presented as mean differences (MDs) between groups with 95% confidence intervals (CIs). We undertook subgroup analyses for age and sex. We undertook sensitivity analyses to assess the effect of sample size on our findings.

MAIN RESULTS

A total of 73 trials met our inclusion criteria. These 73 trials included 5763 participants and were undertaken in 22 countries. Participants were aged from 16 to 84 years and there were approximately 1.5 times as many females as males. The characteristics of walking interventions in the included studies were as follows: the majority of walking interventions was at home/community (n = 50) but supervised (n = 36 out of 47 reported the information of supervision); the average intervention length was 15 weeks, average walking time per week was 153 minutes and the majority of walking intensity was moderate. Many studies were at risk of selection bias and performance bias. Primary outcome We found moderate-certainty evidence suggesting that walking reduces systolic blood pressure (SBP) (MD -4.11 mmHg, 95% CI -5.22 to -3.01; 73 studies, n = 5060). We found moderate-certainty evidence suggesting that walking reduces SBP in participants aged 40 years and under (MD -4.41 mmHg, 95% CI -6.17 to -2.65; 14 studies, n = 491), and low-certainty evidence that walking reduces SBP in participants aged 41 to 60 years (MD -3.79 mmHg, 95% CI -5.64 to -1.94, P < 0.001; 35 studies, n = 1959), and those aged 60 years of over (MD -4.30 mmHg, 95% CI -6.17 to -2.44, 24 studies, n = 2610). We also found low certainty-evidence suggesting that walking reduces SBP in both females (MD -5.65 mmHg, 95% CI -7.89 to -3.41; 22 studies, n = 1149) and males (MD -4.64 mmHg, 95% CI -8.69 to -0.59; 6 studies, n = 203). Secondary outcomes We found low-certainty evidence suggesting that walking reduces diastolic blood pressure (DBP) (MD -1.79 mmHg, 95% CI -2.51 to -1.07; 69 studies, n = 4711) and heart rate (MD -2.76 beats per minute (bpm), 95% CI -4.57 to -0.95; 26 studies, n = 1747). We found moderate-certainty evidence suggesting that walking reduces DBP for participants aged 40 years and under (MD -3.01 mmHg, 95% CI -4.44 to -1.58; 14 studies, n = 491) and low-certainty evidence suggesting that walking reduces DBP for participants aged 41 to 60 years (MD -1.74 mmHg, 95% CI -2.95 to -0.52; 32 studies, n = 1730) and those aged 60 years and over (MD -1.33 mmHg, 95% CI -2.40 to -0.26; 23 studies, n = 2490). We found moderate-certainty evidence that suggests walking reduces DBP for males (MD -2.54 mmHg, 95% CI -4.84 to -0.24; 6 studies, n = 203) and low-certainty evidence that walking reduces DBP for females (MD -2.69 mmHg, 95% CI -4.16 to -1.23; 20 studies, n = 1000). Only 21 included studies reported adverse events. Of these 21 studies, 16 reported no adverse events, the remaining five studies reported eight adverse events, with knee injury being reported five times.

AUTHORS' CONCLUSIONS

Moderate-certainty evidence suggests that walking probably reduces SBP. Moderate- or low-certainty evidence suggests that walking may reduce SBP for all ages and both sexes. Low-certainty evidence suggests that walking may reduce DBP and heart rate. Moderate- and low-certainty evidence suggests walking may reduce DBP and heart rate for all ages and both sexes.

Two Months of Using Global Recommendations for Physical Activity Had No Impact on Cognitive or Motor Functions in Overweight and Obese Middle-Aged Women

BACKGROUND

The effect of globally recommended levels of physical activity on cognition and motor behavior is not completely understood. Therefore, the main aim of this study was to assess the effect of 300 minutes per week of moderate-intensity aerobic exercise on cognitive and motor performance among overweight and obese working-age women.

METHODS

Overweight and obese participants aged 38-56 years were randomized to either a control or an experimental group performing aerobic exercise at 50% to 60% of the peak oxygen consumption for a 2-month period. Changes in aerobic fitness, cardiac autonomic function, brain-derived neurotropic factor levels, and cognitive and motor performance were assessed.

RESULTS

Although aerobic exercise reduced body weight (P < .05) and improved peak oxygen consumption (P < .05), the brain-derived neurotropic factor levels and cognitive and motor performance remained unchanged. Heart rate and blood pressure decreased (P < .05), whereas heart rate variability indices were not affected. No significant correlations between changes in heart rate variability indices and cognition were observed.

CONCLUSIONS

Two months of moderate-intensity aerobic exercise decreased sympathetic activity and improved cardiovascular fitness but had no impact on cognition or motor control among these middle-aged, overweight, and obese women.

Effects of a diabetes-specific care model for hip fractured older patients with diabetes: A randomized controlled trial

OBJECTIVES

To examine the effects of a diabetes-specific care model for hip fractured elderly with diabetes mellitus (DM).

METHODS

A randomized controlled trial was implemented in a 3000-bed medical center in northern Taiwan. Older adults (age ≥ 60) with DM who had hip-fracture surgery (N = 176) were recruited and randomly assigned to diabetes-specific care (n = 88) and usual care (n = 88). Usual care entailed one or two in-hospital rehabilitation sessions. Diabetes-specific care comprised an interdisciplinary care (including geriatric consultation, discharge planning, and in-home rehabilitation) and diabetes-specific care (including dietary and diabetes education, blood pressure control, dyslipidemia management, a glycemic treatment regimen, and rehabilitation exercises). Outcomes including heart rate variability; rehabilitation outcomes; activities of daily living and instrumental activities of daily living were assessed before discharge and 1, 3, 6, 12, 18, 24 months afterwards.

RESULTS

Patients who received diabetes-specific care had significantly higher hip-flexion range of motion (b = 5.24, p < .01), peak-force quadriceps strength of the affected limb (b = 2.13, p < .05), higher total heart rate variability in terms of the time-domain parameter for the mean squared difference between two adjacent normal R-R intervals (b = 11.35, p < .05), and frequency-domain parameters, such as low frequency (b = 42.17, p < .05), and the high frequency-to-low frequency ratio (b = 0.11, p < .01).

CONCLUSIONS

Our diabetes-specific care model enhanced hip-flexion range of motion, peak quadriceps strength of the affected limb, and overall heart rate variability, indicating dynamic responses to environmental changes during the 24 months following hospital discharge, above and beyond the effects of usual care.

The blood pressure variability and baroreflex sensitivity in healthy participants are not determined by sex or cardiorespiratory fitness

BACKGROUND

Heart rate (HR) and blood pressure (BP) autonomic modulation and baroreflex sensitivity (BRS) are important indexes of cardiovascular homeostasis. However, methodological errors are often observed, such as joint analysis of men and women. Another important aspect is that we still do not know whether cardiorespiratory fitness influences these autonomic parameters in healthy individuals.

OBJECTIVES

This study aimed to investigate whether sex can affect BRS, autonomic modulation of HR and BP variabilities (HRV and BPV, respectively), as well as the influence of cardiorespiratory fitness on these autonomic parameters.

METHODS

Healthy men and women (N=120) were assigned to groups according to the peak oxygen consumption (VO2 peak) obtained in the cardiorespiratory test: low cardiorespiratory fitness (VO2 peak: 22-38 ml/kg/min), moderate cardiorespiratory fitness (VO2 peak: 38-48 ml/kg/min), and high cardiorespiratory fitness (VO2 peak>48 ml/kg/min). HRV and BPV evaluations were performed for all groups in the frequency domain by spectral analysis. Spontaneous BRS was assessed using the sequence method.

RESULTS

Women presented lower BP values compared with men. HR did not differ between sexes, but showed an inverse relationship with cardiorespiratory performance. The HRV analysis showed greater sympathetic modulation for men and greater vagal modulation for women. Men and women presented similar results for systolic BPV and BRS, and cardiorespiratory performance did not influence any of the autonomic parameters evaluated.

CONCLUSION

Cardiorespiratory fitness does not interfere with HRV and BPV autonomic modulation or BRS. However, the cardiac modulatory balance differs between sexes, with a greater influence of the autonomic vagal component in women and the sympathetic component in men.

Physical activity and dietary interventions in diabetic neuropathy: a systematic review

PURPOSE

Diabetic neuropathy is a common and disabling disorder, and there are currently no proven effective disease-modifying treatments. Physical activity and dietary interventions in patients with diabetes and diabetic neuropathy have multiple beneficial effects and are generally low risk, which makes lifestyle interventions an attractive treatment option. We reviewed the literature on the effects of physical activity and dietary interventions on length-dependent peripheral neuropathy and cardiac autonomic neuropathy in diabetes.

METHODS

The electronic database PubMed was systematically searched for original human and mouse model studies examining the effect of either dietary or physical activity interventions in subjects with diabetes, prediabetes, or metabolic syndrome.

RESULTS

Twenty studies are included in this review. Fourteen studies were human studies and six were in mice. Studies were generally small with few controlled trials, and there are no widely agreed upon outcome measures.

CONCLUSIONS

Recent research indicates that dietary interventions are effective in modifying diabetic neuropathy in animal models, and there are promising data that they may also ameliorate diabetic neuropathy in humans. It has been known for some time that lifestyle interventions can prevent the development of diabetic neuropathy in type 2 diabetes mellitus subjects. However, there is emerging evidence that lifestyle interventions are effective in individuals with established diabetic neuropathy. In addition to the observed clinical value of lifestyle interventions, there is emerging evidence of effects on biochemical pathways that improve muscle function and affect other organ systems, including the peripheral nerve. However, data from randomized controlled trials are needed.

Modulation of Autonomic Function by Physical Exercise in Patients with Fibromyalgia Syndrome: A Systematic Review

OBJECTIVE

To evaluate the effects of physical exercise on autonomic dysfunction in patients with fibromyalgia syndrome (FM).

LITERATURE SURVEY AND METHODOLOGY

A systematic review of experimental studies published until December 2017 that analyzed the effect of physical exercise on autonomic dysfunction in patients with FM was performed using the PubMed, Pedro, Scopus, ScienceDirect, and Web of Science databases.

SYNTHESIS

A total of 1105 articles were identified, 12 of which were included in the final analysis. The most analyzed exercise modalities were aerobic and resistance exercises. Overall, the studies demonstrated that aerobic exercise performed twice a week with moderate to high intensity was effective in reducing autonomic dysfunction by increasing heart rate variability. Resistance training was associated with reduced symptoms of anxiety and depression as well as increased muscle strength; however, it did not reduce autonomic dysfunction in these patients in the short or long term.

CONCLUSIONS

Preliminary evidence suggests that aerobic exercise reduces autonomic dysfunction in patients with FM, whereas resistance training reduces psychological symptoms such as anxiety and depression.

LEVEL OF EVIDENCE

I.

Heart rate variability responses to a combined exercise training program: correlation with adiposity and cardiorespiratory fitness changes in obese young men

Although the influence of adiposity indices and cardiorespiratory fitness (CRF) on heart rate variability (HRV) has been demonstrated extensively, the causal link between the changes in adiposity as well as in CRF and the alterations in cardiac autonomic function is unclear. Thus, this study aimed to assess the correlation between the changes in adiposity and CRF and the alterations in HRV after 12-week exercise training. Twenty obese sedentary men aged 20.5±1.2 years were randomly assigned into 2 groups (n=10 each): the control (CG) and the exercise group (EG). The EG trained 60 min of combined aerobic, anaerobic and strengthening exercise, 4 sessions/wk for 12 weeks, whilst the CG remained relatively inactive. Measurements of resting HRV, body composition, and peak oxygen consumption (VO_2peak) were obtained at baseline and after the 12-week training program. Compared with CG, the exercise training significantly reduced adiposity indices and improved vagal-related HRV variables and VO_2peak. Significant correlations were observed between changes in HRV variables and adiposity indices and VO_2peak changes. Stepwise regression analysis revealed that changes in a Poincaré plot index (SD1/SD2 ratio) predicted 32.4% of the variance in the relative VO_2peak changes. These findings suggest that obese sedentary young men achieved significant improvements in vagal activity, adiposity indices and aerobic fitness after the exercise training. The higher reduction in fat mass, especially central obesity, the greater alteration of vagal modulation. Moreover, the alteration in resting HRV is a possible predictor for adaptations to exercise training in obese sedentary young men.

Metabolic syndrome impact on cardiac autonomic modulation and exercise capacity in obese adults

Obesity is often associated with increased risk of cardiometabolic morbidities and mortality. However, evidence shows that some obese individuals are more likely to develop such risk factors early in life, including those with Metabolic Syndrome (MetS). Whether the presence of MetS in obese people impairs cardiac autonomic modulation (CAM) remains to be investigated.

METHODS

Cross-sectional study. Sixty-six subjects were classified as normal-weight (NW, n = 24) or obese (BMI ≥ 30 kg·m-2): metabolically healthy (MHO, n = 19) vs unhealthy (MUHO, n = 23: NCEP/ATPIII-MetS criteria). Body composition (bioimpedance), metabolic (glucose-insulin/lipid) and inflammatory profiles were determined. Linear and nonlinear heart rate variability (HRV) indices were computed at rest and during the submaximal six-minute step test (6MST). Blood pressure (BP) and metabolic and ventilatory variables were assessed (oxygen uptake, VO2; carbon dioxide production, VCO2; minute ventilation, VE) during the 6MST and the maximal cardiopulmonary exercise testing (CPX).

RESULTS

All groups reached the same 6MST intensity (VO2 ~ 80% and HR ~ 87% of CPX peak values). Both obese groups, independently of MetS, presented higher BP and lower maximal VO2 than NW. However, HRV differed between groups according to MetS at rest and during exercise: MUHO had lower meanRRi and SD1 than NW and lower RMSSD and pNN50 than MHO at rest; during exercise, the lowest SDNN, TINN, SD1 and Shannon entropy were observed for MUHO. Significant correlations were found between MetS, insulin resistance and HRV indices; and between insulin resistance and aerobic capacity (VO2peak).

CONCLUSION

Obesity per se impairs aerobic-hemodynamic responses to exercise. However, MetS in obese young adults negatively impacts overall HRV, parasympathetic activity and HRV complexity.

Exercise training and cardiac autonomic function in type 2 diabetes mellitus: A systematic review

Cardiac autonomic neuropathy (CAN) is a common complication of type 2 diabetes mellitus (T2DM). It has been found to independently predict all cause and cardiovascular disease (CVD) mortality. It remains unclear whether exercise training could improve autonomic control in T2DM patients. The purpose of this study was to systematically review the effects of exercise training on cardiac autonomic function in T2DM patients. Electronic databases (MEDLINE, CENTRAL, PEDro, Scopus and Web of science) were systematically searched to retrieve relevant evidence. Clinical trials administering exercise training for at least 4 weeks and examining either heart rate variability (HRV), baroreflex sensitivity (BRS), heart rate recovery (HRR) as outcome measures were eligible. Eighteen articles were found to be relevant and were then assessed for characteristics and quality. Fifteen studies out of 18 found that exercise training leads to positive improvements in autonomic function of T2DM patients. Exercise participation enhances cardiac autonomic function of type 2 diabetics and therefore should be implemented in their management programs.

Cardiorespiratory Fitness and Cardiac Autonomic Function in Diabetes

PURPOSE OF REVIEW

This review summarizes the current knowledge on the relationship of physical activity, exercise, and cardiorespiratory fitness (CRF) with cardiovascular autonomic neuropathy (CAN) based on epidemiological, clinical, and interventional studies.

RECENT FINDINGS

The prevalence of CAN increases with age and duration of diabetes. Further risk factors for CAN comprise poor glycemic control, dyslipidemia, abdominal obesity, hypertension, and the presence of diabetic complications. CAN has been also linked to reduced CRF. We recently showed that CRF parameters (e.g., maximal oxidative capacity or oxidative capacity at the anaerobic threshold) are associated with cardiac autonomic function in patients recently diagnosed with type 1 or type 2 diabetes. Exercise interventions have shown that physical activity can increase cardiovagal activity and reduce sympathetic overactivity. In particular, long-term and regularly, but also supervised, performed endurance and high-intense and high-volume exercise improves cardiac autonomic function in patients with type 2 diabetes. By contrast, the evidence in those with type 1 diabetes and also in individuals with prediabetes or metabolic syndrome is weaker. Overall, the studies reviewed herein addressing the question whether favorably modulating the autonomic nervous system may improve CRF during exercise programs support the therapeutic concept to promote physical activity and to achieve physical fitness. However, high-quality exercise interventions, especially in type 1 diabetes and metabolic syndrome including prediabetes, are further required to better understand the relationship between physical activity, fitness, and cardiac autonomic function.

Physical Exercise Improves Heart Rate Variability in Patients with Type 2 Diabetes: A Systematic Review

PURPOSE OF REVIEW

The aim of the present systematic review is to provide an up-to-date analysis of the research on the effects of exercise programs on heart rate variability (HRV) in individuals with type 2 diabetes mellitus (T2DM). An electronic search of the literature (PubMed, PEDro and Web of Science) was performed. "HRV", "heart rate variability", "exercise", "physical" and "diabetes" were the terms used for article retrieval. Lastly, 15 articles were selected. PRISMA methodology was employed and data were extracted according to the PICOS approach.

RECENT FINDINGS

Although HRV is not routinely measured in the management of T2DM, it is an important measure due to its relation with mortality and diabetic neuropathy. Physical exercise has become a therapy for T2DM, because it improves physical fitness and functional capacity, enhances metabolic control and insulin sensitivity, reduces inflammatory markers and neuropathy symptoms and can increase the regenerative capacity of cutaneous axons, slowing or preventing neuropathy progression. However, it is not clear to what extent physical exercise can improve HRV in this population. Participation in the 15 selected studies was similar in men and women (48.01% men and 51.99% women). All the intervention programs included aerobic training, and it was complemented by strength training in four studies. Duration of physical exercise sessions ranged between 30 and 75 min, the frequency being between 2 and 7 days/week. Statistically significant improvements in groups with diabetes, relative to baseline, were observed in nine studies. More than 3 days per week of aerobic training, complemented by strength training, during at least 3 months seems to improve HRV in T2DM. Weekly frequency might be the most important factor to improve HRV. These aspects could help to design better programs based in scientific evidence, incorporating HRV as an important variable associated with diabetic neuropathy and mortality.

Severity of traumatic brain injury correlates with long-term cardiovascular autonomic dysfunction

After traumatic brain injury (TBI), central autonomic dysfunction might contribute to long-term increased mortality rates. Central autonomic dysfunction might depend on initial trauma severity. This study was performed to evaluate differences in autonomic modulation at rest and upon standing between patients with a history of mild TBI (post-mild-TBI patients), moderate or severe TBI (post-moderate–severe-TBI patients), and healthy controls. In 20 post-mild-TBI patients (6–78 months after TBI), age-matched 20 post-moderate–severe-TBI patients (6–94 months after TBI) and 20 controls, we monitored respiration, RR intervals (RRI) and systolic blood pressure (BPsys) at supine rest and upon standing. We determined mainly sympathetic low (LF) and parasympathetic high (HF) frequency powers of RRI fluctuations, sympathetically mediated LF-BPsys powers, LF/HF-RRI ratios, normalized (nu) LF-RRI and HF-RRI powers, and compared data between groups, at rest and upon standing (ANOVA with post hoc testing). We correlated autonomic parameters with initial Glasgow Coma Scale (GCS) scores (Spearman test; significance: p < 0.05). Supine BPsys and LFnu-RRI powers were higher while HFnu-RRI powers were lower in post-moderate–severe-TBI patients than post-mild-TBI patients and controls. LFnu-RRI powers were higher and HFnu-RRI powers were lower in post-mild-TBI patients than controls. Upon standing, only post-mild-TBI patients and controls increased LF-BPsys powers and BPsys and decreased HF-RRI powers. GCS scores correlated positively with LFnu-RRI powers, LF/HF-RRI ratios, and inversely with HFnu-RRI powers, at standing position. More than 6 months after TBI, there is autonomic dysfunction at rest and upon standing which is more pronounced after moderate–severe than mild TBI and in part correlates with initial trauma severity.

Recovery of heart rate variability after treadmill exercise analyzed by lagged Poincaré plot and spectral characteristics

The aim of this study was to analyze the recovery of heart rate variability (HRV) after treadmill exercise and to investigate the autonomic nervous system response after exercise. Frequency domain indices, i.e., LF(ms²), HF(ms²), LF(n.u.), HF(n.u.) and LF/HF, and lagged Poincaré plot width (SD1 _m ) and length (SD2 _m ) were introduced for comparison between the baseline period (Pre-E) before treadmill running and two periods after treadmill running (Post-E1 and Post-E2). The correlations between lagged Poincaré plot indices and frequency domain indices were applied to reveal the long-range correlation between linear and nonlinear indices during the recovery of HRV. The results suggested entirely attenuated autonomic nervous activity to the heart following the treadmill exercise. After the treadmill running, the sympathetic nerves achieved dominance and the parasympathetic activity was suppressed, which lasted for more than 4 min. The correlation coefficients between lagged Poincaré plot indices and spectral power indices could separate not only Pre-E and two sessions after the treadmill running, but also the two sessions in recovery periods, i.e., Post-E1 and Post-E2. Lagged Poincaré plot as an innovative nonlinear method showed a better performance over linear frequency domain analysis and conventional nonlinear Poincaré plot.

After-exercise heart rate variability is attenuated in postmenopausal women and unaffected by estrogen therapy

OBJECTIVE

Delayed heart rate (HR) recovery in the immediate postexercise period has been linked to adverse cardiovascular prognosis. The after effects of an acute bout of exercise on HR modulation in postmenopausal women (PMW) and the influence of estrogen therapy are unknown.

METHODS

In 13 sedentary PMW (54 ± 2 y, mean ± SEM), we assessed HR variability (HRV)--an index of HR modulation--and the influence of estrogen therapy on HRV. HRV in the frequency domain was quantified during supine rest and again 60 minutes after treadmill exercise for 45 minutes, at 60% VO2peak. PMW were studied before and after 4 weeks of oral estradiol. To obtain reference values for the after effects of exercise on HRV in healthy young women, 14 premenopausal women (PreM) completed the identical exercise protocol.

RESULTS

Compared with PreM, PMW demonstrated lower high frequency (vagal modulation) and total HRV (P < 0.05) at rest. In PreM, all HRV values were similar before and after exercise. In contrast, in PMW after exercise, despite having identical HR to PreM, high frequency and total HRV were all lower (all P ≤ 0.01) compared with pre-exercise HRV values. Estrogen therapy had no effect on pre or postexercise values for HRV.

CONCLUSIONS

When compared with PreM, PMW have identical HR, but lower vagal HR modulation at rest and delayed HRV recovery after exercise. Estrogen does not restore baseline HRV or accelerate HRV recovery postexercise, suggesting aging rather than estrogen deficiency per se may lower HRV in PMW.

Arterial baroreflex control of sympathetic nerve activity and heart rate in patients with type 2 diabetes

Despite greater blood pressure reactivity to acute cardiovascular stressors and a higher prevalence of hypertension in type 2 diabetes (T2D) patients, limited information is available regarding arterial baroreflex (ABR) control in T2D. We hypothesized that ABR control of muscle sympathetic nerve activity (MSNA) and heart rate (HR) are attenuated in T2D patients. Seventeen T2D patients (50 ± 2 yr; 31 ± 1 kg/m²), 9 weight-matched controls (WM-CON, 46 ± 2 yr; 32 ± 2 kg/m²) and 10 lean controls (Lean-CON, 49 ± 3 yr; 23 ± 1 kg/m²), underwent bolus infusions of sodium nitroprusside (100 μg) followed 60 s later by phenylephrine (150 μg) and weighted linear regression performed. No group differences in overall sympathetic baroreflex gain were observed (T2D: -2.5 ± 0.3 vs. WM-CON: -2.6 ± 0.2 vs. Lean-CON: -2.7 ± 0.4 arbitrary units·beat·mmHg^-1, P > 0.05) or in sympathetic baroreflex gain when derived separately during blood pressure (BP) falls (nitroprusside) and BP rises (phenylephrine). In contrast, overall cardiac baroreflex gain was reduced in T2D patients compared with Lean-CON (T2D: 8.2 ± 1.5 vs. Lean-CON: 15.6 ± 2.9 ms·mmHg^-1, P < 0.05) and also tended to be reduced in WM-CON (9.3 ± 1.9 ms·mmHg^-1) compared with Lean-CON (P = 0.059). Likewise, during BP rises, cardiac baroreflex gain was reduced in T2D patients and weight-matched controls compared with lean controls (P < 0.05), whereas no group differences were found during BP falls (P > 0.05). Sympathetic and cardiac ABR gains were comparable between normotensive and hypertensive T2D patients (P > 0.05). These findings suggest preserved ABR control of MSNA in T2D patients compared with both obese and lean age-matched counterparts, with a selective impairment in ABR HR control in T2D that may be related to obesity.

Effects of 12 weeks combined aerobic and resistance exercise on heart rate variability in type 2 diabetes mellitus patients

[Purpose] This study evaluated the effects of 12 weeks combined aerobic and resistance exercise on heart rate variability in patients with Type 2 diabetes mellitus. [Subjects and Methods] The subjects were 16 female patients with Type 2 diabetes mellitus selected among the participants of a chronic disease management exercise class at C Region Public Health Center in South Korea. Subjects were randomly assigned to the exercise group (n=8; age, 55.97 ± 7.37) or the control group (n=8; age, 57.53 ± 4.63) The exercise group performed aerobic and resistance exercises for 60 minutes per day, 3 times per week for 12 weeks. Anthropometric measurements, biochemical markers, physical fitness, and heart rate variability were examined. [Results] After 12 weeks of exercise, weight, body fat percentage, waist circumference, blood glucose, insulin resistance, glycated hemoglobin level, systolic blood pressure, and diastolic blood pressure significantly decreased and cardiorespiratory fitness and muscular strength significantly increased in the exercise group. Although heart rate variability measures showed favorable changes with the exercise program, none were significant. [Conclusion] Although the exercise program did not show notable changes in heart rate variability in patients with Type 2 diabetes within the timeframe of the study, exercise may contribute to the prevention and control of cardiovascular autonomic neuropathy.

Exercise training at the maximal fat oxidation intensity improved health-related physical fitness in overweight middle-aged women

Background/Objective

The purpose of this study was to test the hypothesis that exercise training at the maximal fat oxidation (FATmax) intensity would improve the health-related physical fitness in overweight middle-aged women.

Methods

Thirty women (45-59 years old and BMI 28.2 ± 1.8 kg/m²) were randomly allocated into the Exercise and Control groups. Body composition, FATmax, predicted maximal oxygen uptake, heart function during submaximal exercise, stroke volume, left ventricular ejection fraction, trunk muscle strength, and body flexibility were measured before and after the experimental period.

Results

Following the 10 weeks of supervised exercise training, the Exercise group achieved significant improvements in body composition, cardiovascular function, skeletal muscle strength, and body flexibility; whereas there were no changes in these variables of the Control group. There was also no significant change in daily energy intake for all participants before and after the interventions.

Conclusion

The 10-week FATmax intensity training is an effective treatment to improve health-related physical fitness in overweight middle-aged women.

Autonomic function responses to training: Correlation with body composition changes

AIM

The causal relation between autonomic function and adiposity is an unresolved issue. Thus, we studied whether resting heart rate variability (HRV) changes could be used to predict changes in body composition after 16 weeks of individualized exercise training.

METHODS

A total of 117 sedentary overweight/obese adults volunteered to join an intervention group (IN, n=82) or a control group (CON, n=35). The intervention group trained for 30-40 min three times a week with an intensity of 85-100% of individual ventilatory threshold (Thvent). At baseline and after a 16-week training period, resting HRV variables, body composition and peak oxygen uptake (VO2peak) were assessed.

RESULTS

Compared with CON, exercise training significantly improved HRV and body composition and increased VO2peak (P<0.05). Significant correlations were observed between changes of HRV variables and body composition indices and VO2peak (P<0.05). Greater individual changes in HRV in response to exercise training were observed for those with greater total and central fat loss.

CONCLUSION

Individual aerobic-based exercise training was for improving autonomic function and resting HRV responses to aerobic training is a potential indicator for adaptations to exercise training.

Effects of aerobic exercise intensity on 24-h ambulatory blood pressure in individuals with type 2 diabetes and prehypertension

[Purpose] To verify the effects of different intensities of aerobic exercise on 24-hour ambulatory blood pressure (BP) responses in individuals with type 2 diabetes mellitus (T2D) and prehypertension. [Subjects and Methods] Ten individuals with T2D and prehypertension (55.8 ± 7.7 years old; blood glucose 133.0 ± 36.7 mg·dL⁻¹ and awake BP 130.6 ± 1.6/ 80.5 ± 1.8 mmHg) completed three randomly assigned experiments: non-exercise control (CON) and exercise at moderate (MOD) and maximal (MAX) intensities. Heart rate (HR), BP, blood lactate concentrations ([Lac]), oxygen uptake (VO₂), and rate of perceived exertion (RPE) were measured at rest, during the experimental sessions, and during the 60 min recovery period. After this period, ambulatory blood pressure was monitored for 24 h. [Results] The results indicate that [Lac] (MAX: 6.7±2.0 vs. MOD: 3.8±1.2 mM), RPE (MAX: 19±1.3 vs. MOD: 11±2.3) and VO₂peak (MAX: 20.2±4.1 vs. MOD: 14.0±3.0 mL·kg⁻¹·min⁻¹) were highest following the MAX session. Compared with CON, only MAX elicited post-exercise BP reduction that lasted for 8 h after exercise and during sleep. [Conclusion] A single session of aerobic exercise resulted in 24 h BP reductions in individuals with T2D, especially while sleeping, and this reduction seems to be dependent on the intensity of the exercise performed.

Deep breathing acutely improves arterial dysfunction in obese children: evidence of functional impairment?

BACKGROUND AND AIMS

Similarly to diabetes type 2, patients with obesity show insulin resistance and autonomic and vascular abnormalities associated with increased morbidity and mortality. We tested whether arterial dysfunction in obese children may have a functional nature, reversible with appropriate interventions (e.g., by reduction of sympathetic activity), or else results from anatomic arterial modifications (likely irreversible). For this purpose, we tested whether deep breathing (an intervention known to transiently reduce sympathetic activity) could acutely improve arterial function, hence showing a functional abnormality.

METHODS AND RESULTS

A total of 130 obese children and 67 age-matched healthy normal-weight control children were recruited. Arterial function was measured by augmentation index (AIx), by direct analysis of blood pressure contour, and by pulse wave velocity (PWV), during spontaneous and controlled breathing. The markers of metabolic syndrome were evaluated at baseline. AIx showed increased values in obese male participants as compared with the control group. Slow breathing acutely reduced Aix in obese children, to a greater extent than in normal-weight control children. Similarly, the blood pressure contour showed higher values in obese children that were significantly attenuated by slow breathing. Baseline PWV was not altered in obese participants. The markers of metabolic syndrome correlated with AIx and PWV.

CONCLUSIONS

Obese subjects showed impaired arterial function. The acute improvement in vascular abnormalities with reduction in sympathetic activity indicates that this alteration was largely functional, likely related to initial autonomic dysfunction and to metabolic abnormalities. As a consequence, this study provides a rationale for strategies aiming at preventing arterial function deterioration in the early ages.

Peripheral heart action (PHA) training as a valid substitute to high intensity interval training to improve resting cardiovascular changes and autonomic adaptation

PURPOSE

The present study evaluated the effects of peripheral heart action training compared with high intensity interval training on changes in autonomic regulation and physical fitness.

METHODS

Eighteen young adults (9 women, 9 men) (age 24 ± 3 years, BMI of 22.67 kg/m(2), V'O2max 32.89 ml/kg/min) were randomly assigned to either a high intensity interval training group (n = 8) or a peripheral heart action training (PHA) group (n = 10). Before and after training, maximal whole-body muscular strength, time series of beat-to-beat intervals for heart rate variability, and baroreflex sensitivity were recorded. Arterial baroreflex sensitivity and heart rate variability were estimated on both time and frequency domains. Physical fitness level was evaluated with maximum oxygen consumption test.

RESULTS

The effects of PHA whole-body resistance training increased muscular strength and maximum oxygen consumption, with an effect on vagal-cardiac control and cardiovagal baroreflex sensitivity.

CONCLUSIONS

After 30 training sessions performed in 3 months, PHA resistance exercise promoted cardiovascular adaptations, with a decrease in the power spectral component of vascular sympathetic activity and an increase in the vagal modulation. Low-frequency oscillation estimated from systolic blood pressure variability seems to be a suitable index of the sympathetic modulation of vasomotor activity. This investigation also want to emphasize the beneficial effects of this particular resistance exercise training, considering also that the increase in muscular strength is inversely associated with all-cause mortality and the prevalence of metabolic syndrome, independent of cardiorespiratory fitness levels.

Resting heart rate variability and heart rate recovery after submaximal exercise

PURPOSE

Aerobic training accelerates Heart Rate Recovery after exercise in healthy subjects and in patients with coronary disease. As shown by pharmacological autonomic blockade, HRR early after exercise is dependent primarily on parasympathetic reactivation. Thus, accelerated HRR early after exercise in endurance-trained athletes may be attributed to augmented parasympathetic reactivation. In the present study, we tested the hypothesis that the HRR early after submaximal exercise is related to the pre-exercise parasympathetic modulation.

METHODS

Thirty endurance-trained athletes (20 males, 50 ± 7 years) and thirty control subjects (20 males, 52 ± 6 years) performed a submaximal exercise on a cyclo-ergometer. Pre-exercise resting short-term heart rate variability (HRV) parameters in time and frequency-domains were correlated with HRR during the first 30 s, 1 and 2 min after cessation of exercise.

RESULTS

We found that HRR was statistically significantly faster in athletes than in controls at all examination time points (p < 0.05). HF, SDNN and RMSSD were statistically significantly higher in athletes than in controls (p < 0.05), but other resting HRV parameters were not statistically different between groups. After 30 s, 1 and 2 min of recovery, HRR correlation with total power, HF, HFnu and RMSSD was positive, while the correlation with LF/HF was negative for small and positive for larger values. The opposite was true for SDNN.

CONCLUSIONS

These findings support the hypothesis that HRR early after submaximal exercise is related to resting parasympathetic modulation in the middle-aged subjects. In addition, they suggested an optimal range of HRV for maximal HRR after exercise.

Exercising with peripheral or autonomic neuropathy: what health care providers and diabetic patients need to know

Both peripheral and autonomic neuropathies are characterized by a progressive loss of nerve fiber function. Most peripheral neuropathy affects the extremities, particularly the lower legs and the feet, but also the hands, whereas damage to the autonomic nervous system may lead to imbalances between the sympathetic and parasympathetic nerve fibers that innervate the heart and blood vessels, as well as abnormalities in heart rate control and vascular dynamics. To prescribe or engage in exercise that is both safe and effective, health care providers and patients with diabetes mellitus need to increase their understanding of the pathophysiological nature of neuropathies and the physical activity hurdles that may arise from the presence of a neuropathy. With proper care and preventative measures, patients with diabetes mellitus that experience either type of neuropathy can benefit from regular participation in mild to moderate aerobic, resistance, and balance activities, assuming they take any potential alterations into account to ensure that exercise is safe and effective.

Exercise is the real polypill

The concept of a "polypill" is receiving growing attention to prevent cardiovascular disease. Yet similar if not overall higher benefits are achievable with regular exercise, a drug-free intervention for which our genome has been haped over evolution. Compared with drugs, exercise is available at low cost and relatively free of adverse effects. We summarize epidemiological evidence on the preventive/therapeutic benefits of exercise and on the main biological mediators involved.

Cardiac autonomic modulation is determined by gender and is independent of aerobic physical capacity in healthy subjects

BACKGROUND

Aerobic physical capacity plays an important role in reducing morbidity and mortality rates in subjects with cardiovascular diseases. This action is often related to an improvement in the autonomic modulation of heart rate variability (HRV). However, controversies remain regarding the effects of physical training on cardiac autonomic control in healthy subjects. Therefore, our objective was to investigate whether aerobic capacity interferes with the autonomic modulation of HRV and whether gender differences exist.

METHODS

Healthy men and women (N=96) were divided into groups according to aerobic capacity: low (VO2: 22-38 ml/kg(-1) min(-1)), moderate (VO2: 38-48 ml/kg(-1) min(-1)) and high (VO2 >48 ml/kg(-1) min(-1).) We evaluated the hemodynamic parameters and body composition. The autonomic modulation of HRV was investigated using spectral analysis. This procedure decomposes the heart rate oscillatory signal into frequency bands: low frequency (LF=0.04-0.15Hz) is mainly related to sympathetic modulation, and high frequency (HF=0.15-0.5Hz) corresponds to vagal modulation.

RESULTS

Aerobic capacity, regardless of gender, determined lower values of body fat percentage, blood pressure and heart rate. In turn, the spectral analysis of HRV showed that this parameter did not differ when aerobic capacity was considered. However, when the genders were compared, women had lower LF values and higher HF values than the respective groups of men.

CONCLUSION

The results suggest that aerobic physical capacity does not interfere with HRV modulation; however, the cardiac modulatory balance differs between genders and is characterized by a greater influence of the autonomic vagal component in women and by the sympathetic component in men.

Relationship between post-exercise heart rate variability and skinfold thickness

This investigation aimed to determine if groupings based upon sum of skinfold thickness (SF) would reflect the differences in heart rate variability (HRV) measured for up to 30-minutes following maximal exercise, and to determine the extent in variation in post-exercise HRV that could be accounted for between the following independent variables: SF, body mass index (BMI) and maximal oxygen consumption (VO2max). SF and BMI measurements were performed on fifty-four men who completed maximal exercise testing to determine VO2max. HRV was evaluated for five-minutes before (Pre), at 0-5 minutes post- (Post1) and 25-30 minutes post-exercise (Post2), and analyzed by frequency domain [high frequency (HF) power, and HF to low frequency power ratio (LF:HF)). Two groups were formed based on being above or below the sample mean value of SF. HF and LF:HF were significantly higher and lower, respectively, at Pre and Post 2 in Group 1 compared to Group 2 (p < 0.05), which remained after controlling for VO2max and BMI. Furthermore, there was a significant trend toward baseline in post-exercise HRV in Group 1 (p < 0.05) but not in Group 2 (p > 0.05). In addition, SF was the only variable to significantly relate to the post-exercise HRV parameters (p < 0.05). The findings of this investigation suggest greater SF is related to a delayed return of HRV toward baseline from maximal exercise. The association between SF and HRV is independent of VO2max and BMI.

Exercise improves cardiac autonomic function in obesity and diabetes

Physical activity is a key element in the prevention and management of obesity and diabetes. Regular physical activity efficiently supports diet-induced weight loss, improves glycemic control, and can prevent or delay type 2 diabetes diagnosis. Furthermore, physical activity positively affects lipid profile, blood pressure, reduces the rate of cardiovascular events and associated mortality, and restores the quality of life in type 2 diabetes. However, recent studies have documented that a high percentage of the cardiovascular benefits of exercise cannot be attributed solely to enhanced cardiovascular risk factor modulation. Obesity in concert with diabetes is characterized by sympathetic overactivity and the progressive loss of cardiac parasympathetic influx. These are manifested via different pathogenetic mechanisms, including hyperinsulinemia, visceral obesity, subclinical inflammation and increased thrombosis. Cardiac autonomic neuropathy is an underestimated risk factor for the increased cardiovascular morbidity and mortality associated with obesity and diabetes. The same is true for the role of physical exercise in the restoration of the heart cardioprotective autonomic modulation in these individuals. This review addresses the interplay of cardiac autonomic function in obesity and diabetes, and focuses on the importance of exercise in improving cardiac autonomic dysfunction.

Diabetes and technology for increased activity study: the effects of exercise and technology on heart rate variability and metabolic syndrome risk factors

This study tested the hypothesis that an 8-week exercise intervention supported by mobile health (mHealth) technology would improve metabolic syndrome (MetS) risk factors and heart rate variability (HRV) in a population with MetS risk factors. Participants (n = 12; three male; aged 56.9 ± 7.0 years) reported to the laboratory for assessment of MetS risk factors and fitness (VO2max) at baseline (V 0) and after 8-weeks (V 2) of intervention. Participants received an individualized exercise prescription and a mHealth technology kit for remote monitoring of blood pressure (BP), blood glucose, physical activity, and body weight via smartphone. Participants underwent 24-h ambulatory monitoring of R-R intervals following V 0 and V 2. Low and high frequency powers of HRV were assessed from the recording and the ratio of low-to-high frequency powers and low and high frequency powers in normalized units were calculated. One-way repeated measures analysis of variance showed that waist circumference (V 0: 113.1 ± 11.0 cm, V 2: 108.1 ± 14.7 cm; p = 0.004) and diastolic BP (V 0: 81 ± 6 mmHg, V 2: 76 ± 11 mmHg; p = 0.04) were reduced and VO2max increased (V 0: 31.3 ml/kg/min, V 2: 34.8 ml/kg/min; p = 0.02) with no changes in other MetS risk factors. Low and high frequency powers in normalized units were reduced (V 0: 75.5 ± 12.0, V 2: 72.0 ± 12.1; p = 0.03) and increased (V 0: 24.5 ± 12.0, V 2: 28.0 ± 12.1; p = 0.03), respectively, with no other changes in HRV. Over the intervention period, changes in systolic BP were correlated negatively with the changes in R-R interval (r = -0.600; p = 0.04) and positively with the changes in heart rate (r = 0.611; p = 0.03), with no other associations between MetS risk factors and HRV parameters. Thus, this 8-week mHealth supported exercise intervention improved MetS risk factors and HRV parameters, but only changes in systolic BP were associated with improved autonomic function.

Impact of aerobic exercise training on heart rate variability and functional capacity in obese women after gastric bypass surgery

BACKGROUND

Obesity is a major public health concern on a global scale. Bariatric surgery is among the treatment options, resulting in significant and sustainable weight loss as well as amelioration of comorbidities. The purpose of this study was to evaluate whether a 12-week aerobic exercise program positively impacts heart rate variability (HRV) and functional capacity after gastric bypass surgery (GBS) in a female cohort.

METHODS

Of the 52 patients initially recruited, 21 were randomized to a training group (TG) or control group and successfully completed the study. Patients were tested on two occasions: 1 week before GBS and 4 months after GBS. Anthropometric variables, body composition, record of heart rate and R-R intervals, and 6-min walk test (6MWT) were assessed at both time points. The TG underwent an aerobic exercise training program on a treadmill (1-h session, totaling 36 sessions over 12 weeks).

RESULTS

The main findings from this study were: (1) only the TG demonstrated a significant increase (p < 0.05) in all indexes of heart rate variability (HRV) after 12 weeks of aerobic exercise training and (2) only the TG demonstrated a significant increase (p < 0.05) in 6MWT distance and decrease in diastolic blood pressure after aerobic exercise training.

CONCLUSIONS

We conclude that 12 weeks of aerobic exercise training improves cardiac autonomic modulation and functional capacity 4 months after GBS.

[Resource management: ICF-oriented exercise programs for patients with diabetes mellitus type 2. Chronic illnesses and biopsychosocial status]

Common health problems are increasing due to the combination of decreased physical activity demands in everyday life and demographic changes; thus, the importance of exercise therapy is increasing. The incidence and prevalence of today's predominant chronic diseases are directly related to physical activity. However, daily clinical routine does not stay abreast with these changes. The education of physicians, and thus their scope of action, is dominated by biomedical therapy concepts, predominantly drug therapy concepts. Differential and consolidated findings of modern exercise and sport science are astonishingly rare in the counselling and treatment portfolio of medical care. The present disease management program for persons with diabetes mellitus type 2 is a good example. Referring to this background, the authors address the new approach of "ICF-oriented exercise programs and biopsychosocial status." They present resource-related interventional strategies and health care concepts for chronic health disorders like the metabolic syndrome or diabetes mellitus type 2. The relevance and use of active health promotion and care - due to lifestyle- and age-related health problems of the population - will increase in importance and be more commonly recommended.

Dynamic aerobic exercise induces baroreflex improvement in diabetic rats

The objective of the present study was to investigate the effects of an acute aerobic exercise on arterial pressure (AP), heart rate (HR), and baroreflex sensitivity (BRS) in STZ-induced diabetic rats. Male Wistar rats were divided into control (n = 8) and diabetic (n = 8) groups. AP, HR, and BRS, which were measured by tachycardic and bradycardic (BR) responses to AP changes, were evaluated at rest (R) and postexercise session (PE) on a treadmill. At rest, STZ diabetes induced AP and HR reductions, associated with BR impairment. Attenuation in resting diabetes-induced AP (R: 103 ± 2 versus PE: 111 ± 3 mmHg) and HR (R: 290 ± 7 versus PE: 328 ± 10 bpm) reductions and BR dysfunction (R: −0.70 ± 0.06 versus PE: −1.21 ± 0.09 bpm/mmHg) was observed in the postexercise period. In conclusion, the hemodynamic and arterial baro-mediated control of circulation improvement in the postexercise period reinforces the role of exercise in the management of cardiovascular risk in diabetes.

Cardiac autonomic impairment and chronotropic incompetence in fibromyalgia

Introduction

We aimed to gather knowledge on the cardiac autonomic modulation in patients with fibromyalgia (FM) in response to exercise and to investigate whether this population suffers from chronotropic incompetence (CI).

Methods

Fourteen women with FM (age: 46 ± 3 years; body mass index (BMI): 26.6 ± 1.4 kg/m²) and 14 gender-, BMI- (25.4 ± 1.3 kg/m²), and age-matched (age: 41 ± 4 years) healthy individuals (CTRL) took part in this cross-sectional study. A treadmill cardiorespiratory test was performed and heart-rate (HR) response during exercise was evaluated by the chronotropic reserve. HR recovery (deltaHRR) was defined as the difference between HR at peak exercise and at both first (deltaHRR1) and second (deltaHRR2) minutes after the exercise test.

Results

FM patients presented lower maximal oxygen consumption (VO₂ max) when compared with healthy subjects (22 ± 1 versus CTRL: 32 ± 2 mL/kg/minute, respectively; P < 0.001). Additionally, FM patients presented lower chronotropic reserve (72.5 ± 5 versus CTRL: 106.1 ± 6, P < 0.001), deltaHRR1 (24.5 ± 3 versus CTRL: 32.6 ± 2, P = 0.059) and deltaHRR2 (34.3 ± 4 versus CTRL: 50.8 ± 3, P = 0.002) than their healthy peers. The prevalence of CI was 57.1% among patients with FM.

Conclusions

Patients with FM who undertook a graded exercise test may present CI and delayed HR recovery, both being indicative of cardiac autonomic impairment and higher risk of cardiovascular events and mortality.