Cardiovagal modulation and efficacy of aerobic exercise training in obese individuals

Cardiac Autonomic Modulation in Response to Three Types of Exercise in Patients with Type 2 Diabetic Neuropathy

Purpose

Physical exercise is necessary in the handling DM, but it is not distinct which kind of physical exercise can improve cardiac autonomic modulation in T2DM. The purpose of this study was to compare the effects of three different modalities of exercise (aerobic, resistant, and combined) on cardiac autonomic modulation as measured by HRV in patients with type 2 diabetic neuropathy.

Methods

The participants were 45 men (age: 55.24 ± 8.11 years, weight: 89.5 ± 13.4 kg, height: 171.85 ± 6.98 cm, duration of diabetes: 12.51 ± 6.46 years) with type 2 diabetic neuropathy who were clinically free from signs and symptoms of cardiovascular disease. Participants were randomly assigned to one of four groups: aerobic-training (n = 11), dynamic resistant-training (n = 11), Combined-training (n = 11), or a non-exercise control group (n = 12). The exercise groups performed aerobic and resistant exercise for 25-45 min per day, 3-5 times per week for 12 weeks. Anthropometrics, biochemical markers (FBS, HbA1c, Lipid Profile, and Insulin), and heart rate variability in the exercise laboratory and under ambulatory conditions by 3-channel ECG digital Holter recorder were examined.

Results

All time and frequency-domain HRV parameters (except LF power) were significantly improved in the exercise groups, compared with the control group (p < 0.05). SDNN, rMSSD, and HF power were boosted, LF power was not different, and the LF/HF ratio decreased after versus before exercise training, independent of exercise modality. HbA1c in aerobic and resistant-training groups, and insulin and LDL in the resistant-training group were decreased after exercise training (p < 0.05).

Conclusions

Exercise training, independent of modality, in patients with type 2 diabetic neuropathy who were clinically free of the cardiovascular disease cause to significant progress in cardiovascular autonomic function assessed by HRV via enhancing cardio-vagal and reducing cardio-sympathetic tone.

Monitoring and adapting endurance training on the basis of heart rate variability monitored by wearable technologies: A systematic review with meta-analysis

OBJECTIVES

To systematically perform a meta-analysis of the scientific literature to determine whether the outcomes of endurance training based on heart rate variability (HRV) are more favorable than those of predefined training.

DESIGN

Systematic review and meta-analysis.

METHODS

PubMed and Web of Science were searched systematically in March of 2020 using keywords related to endurance, the ANS, and training. To compare the outcomes of HRV-guided and predefined training, Hedges' g effect size and associated 95% confidence intervals were calculated.

RESULTS

A total of 8 studies (198 participants) were identified comprising 9 interventions involving a variety of approaches. Compared to predefined training, most HRV-guided interventions included fewer moderate- and/or high-intensity training sessions. Fixed effects meta-analysis revealed a significant medium-sized positive effect of HRV-guided training on submaximal physiological parameters (g = 0.296, 95% CI 0.031 to 0.562, p = 0.028), but its effects on performance (g = 0.079, 95% CI -0.050 to 0.393, p = 0.597) and V̇O2peak (g = 0.171, 95% CI -0.213 to 0.371, p = 0.130) were small and not statistically significant. Moreover, with regards to performance, HRV-guided training was associated with fewer non-responders and more positive responders.

CONCLUSIONS

In comparison to predefined training, HRV-guided endurance training had a medium-sized effect on submaximal physiological parameters, but only a small and non-significant influence on performance and V̇O_2peak. There were fewer non-responders regarding performance with HRV-based training.

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.

Noninvasive assessment of autonomic modulation of heart rate variability in the Ts65Dn mouse model of Down syndrome: A proof of principle study

Introduction

The Ts65Dn mouse is the most widely used animal model of Down syndrome (DS). Differences in autonomic regulation of heart rate variability (HRV) in individuals with DS have been hypothesized. Pharmacological studies in animal models may help us understand mechanisms underlying observed changes in HRV in people with DS.

Objective

To investigate the use a new, noninvasive technique to assess cardiac autonomic modulation in Ts65Dn mice under the effect of adrenergic and cholinergic agonists.

Method

We recorded electrocardiograms (ECGs) from 12 Ts65Dn and 12 euploid control mice. A 30‐min baseline recording was followed by the injection of an adrenergic (isoproterenol [Iso]) or cholinergic (carbachol [CCh]) agonist. Heart rate and HRV were analyzed using a series of methods customized for mice.

Results and Discussion

The ECG apparatus described here allowed us to detect noninvasively long series of heartbeats in freely‐moving animals. During baseline conditions, the yield of detectable heartbeats was 3%–27% of the estimated total number of events, which increased to 35%–70% during the 15‐min period after either Iso or CCh injections. Ts65Dn mice displayed a robust enhanced Iso‐induced negative chronotropic rebound response compared with euploid control mice. We observed a significantly smaller CCh response in Ts65Dn versus control euploid mice in the 6‐ to 10‐min‐interval postcarbachol injection.

Conclusion

This work showed that the techniques described here are sufficient for this type of study. However, future studies involving the use of more selective pharmacological agents and/or genetic manipulations will be key to advance a mechanistic understanding of cardiac autonomic regulation in DS.

Determination of the Maximal Lactate Steady State by HRV in Overweight and Obese Subjects

The study assessed if the maximal lactate steady state (MLSS) may be determined by HRV in overweight and obese individuals. Fourteen obese (OB) and 14 overweight (OW) participants performed an incremental exercise test and several constant-load tests on a bicycle ergometer to determine the MLSS. HRV was analysed by using time domain and non-linear parameters of the Poincaré plot. Various HRV thresholds (HRVt) were detected and compared with the MLSS. Overall, Bland-Altman plots demonstrated moderate to strong agreements between the power at the MLSS and the power at HRVt, with all HRVt overestimating the MLSS (range: − 14.6 to−19.8 W). All HRVt were detected at higher intensities (69.2–78.8%P _max ) compared to the MLSS (62.6–66.8%P _max ). The primarily vagally modulated parameter HRVt _SD1 revealed higher correlations (r=0.66–0.76) and lower differences (16.8–19.9%) compared to the parameter HRVt _SD2 (r=0.56–r=0.66; 22.4–22.9%). The data suggest a delayed vagal withdrawal during incremental exercise in obese and overweight individuals. For this population, the use of HRV to determine the MLSS seems questionable.

Individual Endurance Training Prescription with Heart Rate Variability

INTRODUCTION

Measures of HR variability (HRV) have shown potential to be of use in training prescription.

PURPOSE

The aim of this study was to investigate the effectiveness of using HRV in endurance training prescription.

METHODS

Forty recreational endurance runners were divided into the HRV-guided experimental training group (EXP) and traditional predefined training group (TRAD). After a 4-wk preparation training period, TRAD trained according to a predefined training program including two to three moderate- (MOD) and high-intensity training (HIT) sessions per week during an 8-wk intensive training period. The timing of MOD and HIT sessions in EXP was based on HRV, measured every morning. The MOD/HIT session was programmed if HRV was within an individually determined smallest worthwhile change. Otherwise, low-intensity training was performed. Maximal oxygen consumption (V˙O2max) and 3000-m running performance (RS3000m) were measured before and after both training periods.

RESULTS

The number of MOD and HIT sessions was significantly lower (P = 0.021, effect size = 0.98) in EXP (13.2 ± 6.0 sessions) compared with TRAD (17.7 ± 2.5 sessions). No other differences in training were found between the groups. RS3000m improved in EXP (2.1% ± 2.0%, P = 0.004) but not in TRAD (1.1% ± 2.7%, P = 0.118) during the intensive training period. A small between-group difference (effect size = 0.42) was found in the change in RS3000m. V˙O2max improved in both groups (EXP: 3.7% ± 4.6%, P = 0.027; TRAD: 5.0% ± 5.2%, P = 0.002).

CONCLUSION

The results of the present study suggest the potential of resting HRV to prescribe endurance training by individualizing the timing of vigorous training sessions.

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.