Exercise Training-Induced Changes in Heart Rate Recovery in Obese Men With Metabolic Syndrome

A comparison of low and high dose of moderate intensity aerobic exercise on heart rate recovery of the sedentary adults: a pragmatic randomized controlled trial

BACKGROUND

Heart rate recovery (HRR) has been used as a prognostication marker of health. A slower drop in HRR is linked to a higher risk of cardiovascular diseases and all-cause mortality. Since aerobic exercise has been shown to have favorable effects on HRR, we aimed to compare the effects of two different aerobic exercise doses on HRR among a sedentary adult population.

METHODS

A pragmatic randomised controlled trial was conducted on 29 healthy sedentary adults (seven males and 22 females) in a 12-week exercise program. They were randomly assigned to group A (75 min/week, N.=15) or group B (150 min/week, N.=14) of moderate intensity aerobic exercise groups. HRR at 1-minute (HRR1), HRR at 2-minute (HRR2), and peak oxygen uptake (VO<inf>2peak</inf>) were measured pre- and post-intervention.

RESULTS

The improvements of HRR1 and HRR2 were seen in both groups but was only significant (P<0.05) for group A with HRR1, -4.07 bpm (post 24.47±6.42 - pre 20.40±5.51, P=0.018) and HHR2, -3.93 bpm (post 43.40±13.61 - pre 39.47±10.68, P=0.046). Group B showed increment of HRR1, -1.14 bpm (post 21.14±5.35 - pre 20.00±6.30, P=0.286) and HRR2, -2.5 bpm, (post 39.36±8.01 - pre 36.86±9.57, P=0.221). Improvement of the VO<inf>2peak</inf> was only significant in group B with an increment of 1.52±2.61 (P=0.049).

CONCLUSIONS

In conclusion, our study suggests that improvements in heart rate recovery (HRR1 and HRR2) among sedentary healthy adults can be achieved by engaging in moderate intensity exercise at a dose lower than the current recommended guidelines. The lower dose seems to be more attainable and may encourage exercise compliance. Future studies should further explore the effects of different exercise volumes on HRR in a larger sample size and also by controlling for BMI or gender.

The effect of endurance, resistance training, and supplements on mitochondria and bioenergetics of muscle cells

Bioenergetics is the study of energy flow between biological systems and the surroundings and is measured quantitatively. Energy flow can be affected by many variables, including lifestyle and exercise, where exercise comes in different types; endurance and resistance training play significant roles in enhancing bioenergetics and promoting health. In addition, a supplementary diet supports recovery and energy production. This review aims to study the effect of endurance training, resistance training, and supplement intake on the muscle cell's bioenergetics. As a conclusion of the information presented in this mini-review, it was found that resistance, endurance training, and supplements can increase mitochondrial biogenesis, fat oxidation, myofibril synthesis, and increase VO₂ max.

Twelve Weeks of Aerobic Exercise at the Lactate Threshold Improves Autonomic Nervous System Function, Body Composition, and Aerobic Performance in Women with Obesity

Background

The present study examined the effects of a prolonged exercise intervention at the lactate threshold (LT) on body composition, aerobic performance, and the autonomic nervous system (ANS) in women with obesity.

Methods

A total of 36 obese Korean women aged 36 to 55 years (mean±standard deviation, 44.8±5.2 years) were randomly assigned to a control group (CON, n=18) or an experimental group (EXP, n=18); and EXP underwent aerobic exercise training three times a week at a heart rate corresponding to the LT (HR_LT) for 12 weeks. All dependent variables (body composition, aerobic performance, and ANS function parameters) were evaluated before and after training.

Results

Compared with the CON group, the EXP group showed significant improvement in body composition (body weight, -4.57 vs. -2.40 kg; body mass index, -1.79 vs. -0.96 kg/m²; %body fat, -4.63 vs. -1.41; fat-free mass, 3.24 vs. -0.08 kg), aerobic performance (oxygen consumption at LT, 5.74 vs. 0.12 mL/kg/min; maximal oxygen consumption, 5.41 vs. 2.14 mL/kg/min; treadmill speed at HR_LT, 1.40 vs. 0.29 km/hr; bicycle load at HR_LT, 18.62 vs. 4.52 w; and ANS function (mean RR, 50.83 vs. -15.04 ms; standard deviation of NN intervals, 5.08 vs. -0.55 ms; root mean square of successive differences, 6.42 vs. 1.87 ms; total power, 0.34 vs. 0.10 ms²; high frequency, 0.32 vs. -0.04 ms²; low frequency/high frequency, -0.09 vs. 0.01).

Conclusion

Aerobic exercise at the LT for 12 weeks is a practical method of improving body composition, aerobic performance, and ANS function for women with obesity.

Effect of different doses of supervised aerobic exercise on heart rate recovery in inactive adults who are overweight or obese: results from E-MECHANIC

PURPOSE

Heart rate recovery (HRR) after exercise is an independent risk factor for cardiovascular disease and mortality. Regular aerobic exercise can improve HRR, yet little is known regarding the dose necessary to promote increases. The aim was to assess the impact of different doses of vigorous-intensity aerobic exercise on HRR in individuals with overweight/obesity.

METHODS

Data from 137 sedentary adults with overweight/obesity from E-MECHANIC were analyzed. Participants were randomized to either a moderate-dose exercise group (8 kcal/kg body weight/week; KKW), a high-dose exercise group (20 KKW), or a non-exercise control group. HRR was defined as the difference between peak heart rate (HR) during a graded exercise test and the HR after exactly 1 min of active recovery at 1.5 mph and level grade.

RESULTS

Change in HRR did not differ significantly by exercise group; therefore, the data from both exercise groups were combined. The combined exercise group showed an improvement in HRR of 2.7 bpm (95% CI 0.1, 5.4; p = 0.04) compared to the control group. Those participants who lost more weight during the intervention (non-compensators) increased HRR by 6.2 bpm (95% CI 2.8, 9.5; p < 0.01) compared to those who lost less weight (compensators). Multiple linear regression models indicated that improvements in HRR are independently associated with increases in VO_2peak (β = 0.4; 95% CI 0.1, 0.7; p = 0.04) but also influenced by concomitant weight loss (β = 0.6; 95% CI 0.2, 1.1; p = 0.01).

CONCLUSION

Exercise-induced improvements in 1-min HRR are likely due to increases in cardiorespiratory fitness as well as concomitant weight loss.

Effects of weight changes in the autonomic nervous system: A systematic review and meta-analysis

BACKGROUND

Obesity has been linked to autonomic dysfunction, which is thought to be one of the main contributors for hypertension, cardiac remodelling and death. Exercise and diet-based weight loss are the mainstay therapy for obesity, but there is a paucity of data regarding the effect of weight changes in autonomic nervous system (ANS) activity.

OBJECTIVE

To describe the impact of weight changes in autonomic nervous system.

METHODS

A systematic literature search of four biomedical databases was performed evaluating effects of weight changes, thorough diet and/or exercise-based interventions, in the following ANS outcomes: heart rate variability, namely low frequency (LF)/high frequency (HF) ratio (LF/HF ratio), normalized units of LF (LFnu) and HF (HFnu), muscle sympathetic nerve activity (MSNA), noradrenaline spillover rate (NA-SR), standard deviation of normal-to-normal intervals (SDNN), root mean square of successive differences (RMSSD), baroreflex sensitivity and pupillometry. Quality appraisal was performed using the GRADE methodology and, where fitting, studies with comparable outcomes were pooled for meta-analysis.

RESULTS

Twenty-seven studies - 7 controlled clinical trials and 20 observational studies - were included. Weight gain was reported in 4 studies and weight loss in all the other studies. Interventions inducing weight changes included: hypocaloric or hypercaloric diets, exercise (strength, endurance or aerobic training) and hypocaloric diet coupled with exercise programs. Most studies which resulted in weight loss reported decreases in LF/HF ratio, LFnu, MSNA burst frequency and incidence, NA-SR, and an increase of baroreflex sensitivity, HF, HFnu and RMSSD, pointing to a parasympathetic nervous system activation. Meta-analysis regarding weight loss interventions showed a significant pooled effect size (95% CI) with a decreased of MSNA burst frequency -5.09 (-8.42, -1.75), MSNA incidence -6.66 (-12.40, -0.62), however this was not significant for SDNN 14.32 (-4.31, 32.96). Weight gain was associated with an increase in LF/HF, LFnu, MSNA burst frequency and incidence. The weight loss effects were potentiated by the association of hypocaloric diet with exercise. Nevertheless, weight changes effects in these outcomes were based in low or very low quality of evidence.

CONCLUSIONS

Diet and exercise based weight loss appears to increase parasympathetic and decrease sympathetic activity, the opposing effects being observed with weight gain. These findings are not uniformly reported in the literature, possibly due to differences in study design, methodology, characteristics of the participants and techniques used to estimate autonomic nervous activity.

Neuroendocrinological and Epigenetic Mechanisms Subserving Autonomic Imbalance and HPA Dysfunction in the Metabolic Syndrome

Impact of environmental stress upon pathophysiology of the metabolic syndrome (MetS) has been substantiated by epidemiological, psychophysiological, and endocrinological studies. This review discusses recent advances in the understanding of causative roles of nutritional factors, sympathomedullo-adrenal (SMA) and hypothalamic-pituitary adrenocortical (HPA) axes, and adipose tissue chronic low-grade inflammation processes in MetS. Disturbances in the neuroendocrine systems for leptin, melanocortin, and neuropeptide Y (NPY)/agouti-related protein systems have been found resulting directly in MetS-like conditions. The review identifies candidate risk genes from factors shown critical for the functioning of each of these neuroendocrine signaling cascades. In its meta-analytic part, recent studies in epigenetic modification (histone methylation, acetylation, phosphorylation, ubiquitination) and posttranscriptional gene regulation by microRNAs are evaluated. Several studies suggest modification mechanisms of early life stress (ELS) and diet-induced obesity (DIO) programming in the hypothalamic regions with populations of POMC-expressing neurons. Epigenetic modifications were found in cortisol (here HSD11B1 expression), melanocortin, leptin, NPY, and adiponectin genes. With respect to adiposity genes, epigenetic modifications were documented for fat mass gene cluster APOA1/C3/A4/A5, and the lipolysis gene LIPE. With regard to inflammatory, immune and subcellular metabolism, PPARG, NKBF1, TNFA, TCF7C2, and those genes expressing cytochrome P450 family enzymes involved in steroidogenesis and in hepatic lipoproteins were documented for epigenetic modifications.

Heart rate recovery after physical exertion tests in elderly hypertensive patients undergoing resistance training

Abstract Introduction: Heart rate recovery after exercise is a valuable variable, associated with prognosis and it has been used as an indicator of cardiorespiratory fitness, especially in patients with heart disease, as hypertensive patients. Objective: This study aimed to analyze the response of heart rate recovery in elderly hypertensive patients undergoing a resistance training program. Methods: Sample was composed for 10 elderly women with a mean age of 70.7 ± 7.4 years. Exercise test and six-minute walk test were developed and we checked heart rate recovery in the 1st and 2nd minute post tests, before and after resistance training. Results: There was an increase in mean heart rate recovery in the analyzed minutes in both tests, but only in the 1st minute after six minutes walk test we found a significant increase (p = 0.02). Conclusion: The results suggest the efficacy of resistance training to improve cardiorespiratory fitness of elderly hypertensive patients.

Relation between heart rate recovery after exercise testing and body mass index

INTRODUCTION

Impaired heart rate (HR) recovery after exercise testing is considered a predictor of cardiovascular mortality as it reflects vagus nerve dysfunction.

OBJECTIVE

To assess the relationship between body mass index (BMI) and HR recovery after exercise.

METHODS

We analyzed the records of 2443 patients of both sexes, aged between 20 and 59 years, in sinus rhythm, not using negative chronotropic agents and with no myocardial ischemic response to exercise testing carried out at a specialist clinic, between 2005 and 2011. BMI was categorized as normal (18.5-<25 kg/m(2)), overweight (25-≤30 kg/m(2)) or obese (>30 kg/m(2)). The different BMI groups were compared in terms of HR recovery after exercise, which was calculated as the difference between maximum HR during exercise and in the first minute of recovery. Recovery was considered impaired when the difference was ≤12 bpm.

RESULTS

Eighty-seven (3.6%) patients presented impaired recovery, which was three times more prevalent in the obese group and twice as prevalent in the overweight group compared with the normal group (p<0.001 and p=0.010, respectively). Obese patients presented higher basal HR and lower maximum HR, as well as reduced chronotropic reserve (p<0.001). In multivariate analysis, impaired HR recovery was associated with overweight (relative risk [RR]=1.8; p=0.035), obesity (RR=2; p=0.016), number of metabolic equivalents (RR=0.82; p<0.001) and resting HR (RR=1.05; p<0.001). The hazard ratio for hypertension was 2 (p=0.083, NS).

CONCLUSION

Impaired HR recovery was associated with higher BMI, demonstrating that obese individuals present vagus nerve dysfunction.

Low-volume, high-intensity, aerobic interval exercise for sedentary adults: VO₂max, cardiac mass, and heart rate recovery

PURPOSE

The aim of this study was to compare the effects of low-volume, high-intensity aerobic interval training (HAIT) on maximal oxygen consumption (VO₂max), left ventricular (LV) mass, and heart rate recovery (HRR) with high-volume, moderate-intensity continuous aerobic training (CAT) in sedentary adults.

METHODS

Twenty-four healthy but sedentary male adults (aged 29.2 ± 7.2 years) participated in an 8-week, 3-day a week, supervised exercise intervention. They were randomly assigned to either HAIT (18 min, 180 kcal per exercise session) or CAT (45 min, 360 kcal). VO₂max, LV mass (3T-MRI), and HRR at 1 min (HRR-1) and 2 min (HRR-2) after maximal exercise were measured pre- and post-intervention.

RESULTS

Changes in VO₂max during the 8-week intervention were significant (P < 0.01) in both groups (HAIT, 8.7 ± 3.2 ml kg(-1) min(-1), 22.4 ± 8.9%; CAT, 5.5 ± 2.8 ml kg(-1) min(-1), 14.7 ± 9.5%), while the VO₂max improvement in HAIT was greater (P = 0.02) than in CAT. LV mass in HAIT increased (5.1 ± 8.4 g, 5.7 ± 9.1%, P = 0.05), but not in CAT (0.9 ± 7.8 g, 1.1 ± 8.4%, P = 0.71). While changes in HRR-1 were not significant in either group, change in HRR-2 for HAIT (9.5 ± 6.4 bpm, 19.0 ± 16.0%, P < 0.01) was greater (P = 0.03) than for CAT (1.6 ± 10.9 bpm, 3.9 ± 16.2%, P = 0.42).

CONCLUSIONS

This study suggests that HAIT has potential as a time-efficient training mode to improve cardiorespiratory capacity and autonomic nervous system function in sedentary adults.

Effects of low calorie diet-induced weight loss on post-exercise heart rate recovery in obese men

[Purpose]

Heart Rate Recovery (HRR) after maximum exercise is a reactivation function of vagus nerve and an independent risk factor that predicts cardiovascular disease and mortality. Weight loss obtained through dietary programs has been employed as a therapy to reduce risks of cardiovascular disease and obesity.

[Methods]

Eighteen subjects of middle aged obese men (age 44.8 ± 1.6 yrs, BMI 29.7 ± 0.5 kg/m²) were selected for this study. As a weight loss direction, the nutritional direction of low-calorie diet mainly consisted of carbohydrate, protein, and fat has been conducted for 3 months. Blood pressure was measured after overnight fasting, and blood samples were collected from the antecubital vein before and after weight loss program. All the pre- and post-exercise ‘HRR decay constant’s were assessed by using values of HRR (heart recovery rate; 2 minutes) and HR measured after reached to the maximal oxygen uptake (VO₂max) exploited the bicycle ergometer.

[Results]

After the completion of weight loss program, body weight and BMI were significantly decreased, but the Heart Rate (HR) after maximum exercise and in steady state were not changed significantly (p > 0.05). The post-exercise HRR after the weight loss did not show significant changes in perspectives of 30 seconds (-16.6 ± 2.3 to -20.2 ± 2.1 beats/min, p > 0.05) and 60 seconds (-33.5 ± 3.4 to -34.6 ± 2.8 beats/min, p > 0.05) respectively but in perspectives of 90 seconds (-40.9 ± 2.6 to -48.1 ± 3.1 beats/min, p < 0.05) and 120 seconds (-48.6 ± 2.6 to -54.3 ± 3.5 beats/min, p < 0.05), they were decreased significantly. Pre-’HRR decay constant’s of 0.294 ± 0.02 %/second were significantly increased to post-values of 0.342 ± 0.03 %/second (p = 0.026). Changes in ‘HRR decay constant’ were significantly correlated with changes in blood glucose (r = -0.471, p < 0.05) and maximal oxygen consumption (VO₂max, r = 0.505, p < 0.05) respectively.

[Conclusions]

The low-calorie diet directed to obese middle aged men for 3 months significantly improved the HRR after maximum exercise, and this improvement in cardiovascular autonomic nerve system was estimated to be involved with improvements in blood glucose and maximal oxygen consumption.

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.

Impact of a physician-supervised exercise-nutrition program with testosterone substitution in partial androgen-deficient middle-aged obese men

Background

Partial androgen deficiency syndrome in the aging male is associated with signs of aging such as a development of abdominal obesity, sexual dysfunction, increase body fat, weight gain and the development of cardiac disease.

Objective

We assessed the outcome of a commercially available physician supervised nutrition and exercise program with concomitant testosterone replacement therapy in middle age obese men with partial androgen deficiency in order to reduce cardiac risks factors.

Methods

Fifty-six self referred men without diabetes mellitus, hypertension, or cardiovascular disease (ages 52.3 ± 7.8 years) were randomly selected from a large cohort. Baseline weight, body fat composition, fasting glucose, hemoglobin A1c and fasting lipid levels, as well as free and total testosterone levels were assessed. All patients were assessed and followed 6–18 months after initiation of the program. The program consisted of a low glycemic load balanced nutrition diet, a recommended structured daily exercise program of 30–60 minutes, as well as once to twice weekly intramuscular testosterone injections (113.0 ± 27.8 mg).

Results

At follow up, weight was reduced from 233.9 ± 30.0 pounds (lbs) to 221.3 ± 25.1 lbs (P < 0.001), BMI was reduced from 33.2 ± 3.3 kg/m² to 31.3 ± 2.8 kg/m² (P < 0.0001). Total body fat was 27.1% ± 5.2% vs. 34.3% ± 5.7% at baseline (P < 0.0001). Fasting glucose was reduced from 95.3 ± 14.4 mg/dL to 87.5 ± 12.6 mg/dL (P < 0.0001). Total cholesterol was reduced from 195.4 ± 33.0 mg/dL to 172.7 ± 35.0 mg/dL (P < 0.005). No clinically significant adverse events were recorded.

Conclusions

Testosterone replacement therapy in middle aged obese men with partial androgen deficiency appeared safe and might have promoted the effects of a weight reduction diet and daily exercise program as long as an adequate physician supervision and follow up was granted. The combination therapy significantly reduced coronary risk factors such as glucose intolerance and hyperlipidemia.

Blunted heart rate recovery is improved following exercise training in overweight adults with obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) predisposes individuals to cardiovascular morbidity, and cardiopulmonary exercise test (CPET) markers prognostic for cardiovascular disease have been found to be abnormal in adults with OSA. Due to the persistence of OSA and its cardiovascular consequences, whether the cardiovascular adaptations normally conferred by exercise are blunted in adults not utilizing established OSA treatment is unknown. The aims of this study were to document whether OSA participants have abnormal CPET responses and determine whether exercise modifies these CPET markers in individuals with OSA.

METHODS

The CPET responses of 43 sedentary, overweight adults (body mass index [BMI]>25) with untreated OSA (apnea-hypopnea index [AHI]≥ 15) were compared against matched non-OSA controls (n=9). OSA participants were then randomized to a 12-week exercise training (n=27) or stretching control treatment (n=16), followed by a post-intervention CPET. Measures of resting, exercise, and post-exercise recovery heart rate (HRR), blood pressure, and ventilation, as well as peak oxygen consumption (VO(2peak)), were obtained.

RESULTS

OSA participants had blunted HRR compared to non-OSA controls at 1 (P=.03), 3 (P=.02), and 5-min post-exercise (P=.03). For OSA participants, exercise training improved VO2 peak (P=.04) and HRR at 1 (P=.03), 3 (P<.01), and 5-min post-exercise (P<.001) compared to control. AHI change was associated with change in HRR at 5-min post-exercise (r=-.30, P<.05), but no other CPET markers.

CONCLUSIONS

These results suggest that individuals with OSA have autonomic dysfunction, and that exercise training, by increasing HRR and VO2 peak, may attenuate autonomic imbalance and improve functional capacity independent of OSA severity reduction.

Walk-run transition speed training as an efficient exercise adjunct to dietary restriction in the management of obesity: a prospective intervention pilot study

OBJECTIVE

The aim of this study was to test the utility of preferred walk-run transition speed (WRTS) in exercise training adjunct to dietary restriction for obesity management in healthy obese women.

MATERIALS AND METHODS

37 obese women (age: 35 ± 9 years, body mass index (BMI): 34.9 ± 4.6 kg/m(2)) were assigned to an intervention pilot study during 6 months of restricted diet alone (RD) followed by 6 months of RD combined with WRTS (RD and WRTS) as a training exercise. Body mass, waist circumference (WC), fat mass (FM), fat free mass (FFM), active cell mass (ACM), fasting glucose, serum lipids (triacylglycerol (TG), total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), apo-lipoproteins A1 (ApoA1) and B (ApoB)], leptin and insulin concentrations, and HOMA-IR were assessed at baseline (T0), at the end of the RD alone (T1), and at the end of the RD and WRTS programme (T2).

RESULTS

Mean weight loss was 8.6 ± 4.9 kg and 2.2 ± 2.9 kg for (T0-T1) and (T1-T2), respectively. Significant BMI and WC reductions were reported at T1 and T2. FM decreased significantly both with RD and with RD and WRTS training whereas FFM and ACM increased with RD and WRTS training only. TG decreased significantly with the two phases of the programme. A significant increase in HDL-C, and a decrease in LDL-C and TC/HDL-C ratio were noticed with RD and WRTS training. Heart rate monitored in training improved significantly after RD and WRTS training. A significant relationship (r = 0.542, p < 0.02) was demonstrated between reductions in serum leptin and insulin concentrations observed with both RD and WRTS training.

CONCLUSION

The addition of WRTS training to RD promoted a greater reduction in body mass, WC, FM, leptin and insulin concentrations, improved metabolic and cardiovascular risk factors, and enhanced cardiovascular fitness.