Resistance exercise training in patients with heart failure

The utility, safety and physiological adaptations of resistance exercise training in patients with chronic heart failure (CHF) are reviewed and recommendations based on current research are presented. Patients with CHF have a poor clinical status and impaired exercise capacity due to both cardiac limitations and peripheral maladaptations of the skeletal musculature. Because muscle atrophy has been demonstrated to be a hallmark of CHF, the main principle of exercise programmes in such patients is to train the peripheral muscles effectively without producing great cardiovascular stress. For this reason, new modes of training as well as new training methods have been applied. Dynamic resistance training, based on the principles of interval training, has recently been established as a safe and effective mode of exercise in patients with CHF. Patients perform dynamic strength exercises slowly, on specific machines at an intensity usually in the range of 50-60% of one repetition maximum; work phases are of short duration (< or =60 seconds) and should be followed by an adequate recovery period (work/recovery ratio >1 : 2). Patients with a low cardiac reserve can use small free weights (0.5, 1 or 3 kg), elastic bands with 8-10 repetitions, or they can perform resistance exercises in a segmental fashion. Based on recent scientific evidence, the application of specific resistance exercise programmes is safe and induces significant histochemical, metabolic and functional adaptations in skeletal muscles, contributing to the treatment of muscle weakness and specific myopathy occurring in the majority of CHF patients. Increased exercise tolerance and peak oxygen consumption (V-dotO(2peak)), changes in muscle composition, increases in muscle mass, alterations in skeletal muscle metabolism, improvement in muscular strength and endurance have also been reported in the literature after resistance exercise alone or in combination with aerobic exercise. According to new scientific evidence, appropriate dynamic resistance exercise should be recommended as a safe and effective alternative training mode (supplementary to conventional aerobic exercise) in order to counteract peripheral maladaptation and improve muscle strength, which is necessary for recreational and daily living activities, and thus quality of life, of patients with stable, CHF.     

冠心病介入治疗后应用康复训练对患者 运动耐量提升影响

目的探讨冠心病(CHD)介入治疗后应用康复训练对患者运动耐量提升的影响。方法选取石家庄市第一医院自2016年2月至2018年12月收治的180例CHD患者为研究对象。接受介入治疗后,将患者分为A组与B组,每组各90例。A组患者不采用康复训练,B组患者采用康复训练。观察并比较两组患者静息、运动状态下的心率、血压的变化情况及经平板运动试验的主要参数。结果 A、B两组患者静息时的心率、收缩压、舒张压与心率血压乘积比较,差异无统计学意义(P>0.05);A组患者运动所测量的心率、收缩压、舒张压与心率血压乘积均高于B组,差异有统计学意义(P<0.05)。两组患者总运动时间、ST段压低1 mm时间、最大ST段压低幅度、运动至心绞痛出现时间、最大运动耐量比较,差异均有统计学意义(P<0.05)。结论 CHD介入治疗后应用康复训练能够提高患者的运动耐量,促进CHD患者的身心恢复。     

Emotional responsiveness after low- and moderate-intensity exercise and seated rest

PURPOSE: Few experiments have been conducted regarding the effects of exercise on emotional responsiveness. The aim of this experiment was to determine whether anxiety-reducing conditions of low- and moderate-intensity cycling exercise lead to changes in emotional responsiveness to pictures designed to elicit pleasant, neutral, and unpleasant emotions. METHODS: 24 healthy college women completed counterbalanced conditions of 25 min of low- and moderate-intensity cycling exercise and seated rest. Indices of emotional responsiveness, including the acoustic startle eyeblink and corrugator supercilii responses, as well as baseline corrugator supercilii electromyographic (EMG) activity, were measured immediately before and 20 min after each condition while participants viewed pleasant, neutral, and unpleasant pictures from the International Affective Picture System. RESULTS: State anxiety was significantly reduced 20 min after each condition. Startle response magnitude was modulated by the affective content of the pictures and was reduced after each condition in response to each type of picture. Baseline corrugator EMG activity did not change after seated rest but decreased in an exercise intensity-dependent fashion after cycling. Corrugator EMG responses during the pictures were not different between conditions or from pre- to post-conditions. CONCLUSION: The findings suggest that cycling exercise results in decreased baseline activity of facial muscles involved in the expression of emotion but does not lead to changes in appetitive or defensive responses to emotional stimuli. Furthermore, anxiolytic conditions of low- and moderate-intensity cycling exercise and seated rest are related to decreased startle magnitude in healthy college women.     

Plasma glutamine responses to high-intensity exercise before and after endurance training

Glutamine responses to strenuous interval exercise were examined before and after 6 weeks of endurance training. Glutamine measures were obtained before and after the interval exercise sessions and training in untrained males assigned to training (T; n = 10) or control (C; n = 10) groups. Before training, C and T group glutamine progressively decreased (p < 0.05) by 18% and 16%, respectively, by 150-min postinterval exercise. Over the training period C group glutamine did not change, while T group values increased (p < 0.05) by 14%. After training, glutamine again decreased (p < 0.05) by similar percentages (C = 16% and T = 15%) by 150-min postinterval exercise, but the T group recorded higher (p < 0.05) resting and postexercise glutamine concentrations than the C group. Training induced increases in glutamine may prevent the decline in glutamine levels following strenuous exercise falling below a threshold where immune function might be acutely compromised.     

The response of circulating omentin-1 concentration to 16-week exercise training in male children with obesity

Objectives: The purpose of the present study was to investigate the effects of the 16-week exercise training program on serum omentin-1 in relation to change in insulin resistance in obese male children.

Methods: Thirty-two obese male children, aged 9–12 years, were randomly assigned into Exercise Group (ExG; n = 16) and Control Group (CG; n = 16). ExG participated in a 16-week exercise training program which combined various forms of aerobic activities and resistance training. Body composition, body mass index (BMI), waist circumference (WC), fasting glucose and insulin, homeostasis model assessment estimate of insulin resistance (HOMA2-IR), blood lipids and serum omentin-1 were assessed before and after 16 weeks of training.

Results: Exercise training significantly decreased body mass (7.5%), BMI (7.6%), WC (4.3%), body fat % (15%), fasting insulin (18.5%), total cholesterol (TC) (5.4%), low-density lipoprotein cholesterol (LDL-C) (17%) and triglyceride (TG) (7.4%) compared to CG. Between-groups comparison showed a considerable exercise-induced upregulation in omentin-1 (ES = 89; P < 0.05) levels. Furthermore, in ExG serum omentin-1 levels were significantly increased from 24.5 ± 8.4 to 35.9 ± 9.3 ng/ml (45%; P < 0.001) after the training program, which was accompanied with significantly decreased fasting insulin (P < 0.001). The changes in omentin-1 concentrations correlated with the changes in BMI (r = ?0.67, P < 0.001), WC (r = ?0.62, P = 0.002), body fat % (r = ?0.50, P = 0.004), insulin (r = ?0.65, P = 0.001), HOMA2-IR (r = ?0.60, P = 0.004), TC (r = ?0.53, P = 0.004) and LDL-C (r = ?0.51, P = 0.004) in ExG. BMI (β = ?0.50, P = 0.009) and fasting insulin (β = ?0.54, P = 0.006) changes were found to be independent predictors of omentin-1 increment in multiple regression analysis.

Conclusion: Exercise training resulted in a significant increase in serum omentin-1 concentrations in children with obesity. The ?ndings suggest that exercise-induced changes in omentin-1 may be associated with the bene?cial effects of exercise on reduced insulin and weight lost.     

Influence of short-term endurance exercise training on heart rate variability

PURPOSE: To examine the influence of 2 wk (eight sessions) of endurance training on cardiac autonomic modulation, as measured by heart rate variability (HRV). METHODS: Twenty-four males (mean age: 23.1 yr) were randomized to an exercise (EX; N = 12) or control group (CT; N = 12). EX trained for eight sessions (4x wk-1, 40 min, 80-85% HRreserve) on a cycle ergometer. ECG tracings were collected during 5 min of paced breathing (12 breaths x min-1 (PB)), 5 min of spontaneous breathing (SB1), 5 min of 70 degrees head-up tilt (TILT), and a second 5-min period of spontaneous breathing (SB2). Data were collected before (test 1), during (tests 2-4), and 48 h after (test 5) the 2-wk period. HRV was reported as the standard deviation of RR intervals, and as natural logarithm of the normalized units (NU) of high- and low-frequency power (lnHF and lnLF). RESULTS: EX exhibited a significant increase in peak oxygen consumption (8%). During PB and TILT conditions, ANOVA revealed a group x time interaction such that EX exhibited lower lnLFNU and lnLF/lnHF during test 5 compared with test 1. CONCLUSION: These data suggest that eight endurance exercise-training sessions performed over 2 wk enhance the relative vagal modulation of the heart during PB and TILT, but not during SB.     

Lipoprotein subfraction changes after continuous or intermittent exercise training

PURPOSE: This study compared total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) and their respective subfractions after completing 4 wk of either intermittent (INT-EX) or continuous (CON-EX) aerobic exercise training (TRAIN). METHODS: Untrained males (N = 7) and females (N = 11) completed 4 wk of TRAIN of supervised treadmill jogging occurring 5 d.wk(-1) for 30 min per session at 60% VO2max (75% HRmax). CON-EX was a single 30-min bout. INT-EX consisted of three 10-min bouts separated by 20 min of seated rest. Pre- and post-TRAIN fasting plasma samples were collected after subjects had followed 48 h of activity restriction and a 24-h repeated diet including a 12-h dietary fast. Postprandial lipemia was measured for 8 h following a standardized high-fat meal. RESULTS: Fasting triglycerides and very LDL-C were not affected by TRAIN, and TRAIN did not change postprandial area under the curve or peak in either group. With groups combined, TRAIN significantly decreased TC, total LDL-C, and the TC:HDL ratio, and increased HDL-C subfraction 2 and LDL mean particle size. Total intermediate-density lipoprotein cholesterol remained unchanged at post-TRAIN, and was not different between groups. CONCLUSIONS: To prevent dyslipidemia, our findings suggest that persons who are normolipidemic can improve the lipoprotein profile equally with CON-EX and INT-EX by lowered TC through the sum of changes in LDL-C subfractions, increased mean LDL particle size, and increased HDL-C subfraction 2 concentration.     

Stability of dyspnea ratings after exercise training in patients with COPD

PURPOSE: The purpose of this study was to examine whether patients with chronic obstructive pulmonary disease (COPD) would report similar ratings of dyspnea at the same relative exercise intensity after participation in pulmonary rehabilitation. METHODS: Forty-two patients with COPD performed incremental cardiopulmonary exercise testing before and after completion of a 6-wk exercise-training program. Subjects rated dyspnea on the 0-10 category-ratio (CR-10) scale each minute of the exercise test. RESULTS: Both responders (21 patients who exhibited an increase in [OV0312]O(2peak) after pulmonary rehabilitation) and nonresponders (21 patients who had no increase in [OV0312]O(2peak)) reported slightly lower ratings of dyspnea ( approximately 0.5 on the CR-10 scale) at the same relative (50% and 75% of [OV0312]O(2peak)) exercise intensities. These changes in dyspnea ratings after pulmonary rehabilitation were not significantly different between responders and nonresponders. CONCLUSION: The study suggests that patients with COPD can use the same ratings of dyspnea to monitor training at the same relative exercise intensity whether they achieve a physiological training response or not.     

Normalization of diastolic dysfunction in type 2 diabetics after exercise training

PURPOSE: The purpose of this study was to evaluate the impact of aerobic exercise training on left ventricular diastolic dysfunction (LVDD) and exercise capacity in subjects with type 2 diabetes. METHODS: Twenty-three sedentary subjects with well-controlled type 2 diabetes, free of coronary disease and having different degrees of LVDD, participated in the study. Subjects were treated with oral hypoglycemic agents and/or diet. Eleven subjects (EX) (age: 58 +/- 5 yr; mean +/- SD) underwent a 3-month aerobic exercise training program using a cycle ergometer, whereas a control group (CONT) of 12 subjects (57 +/- 6 yr) maintained their activities of daily living. Exercise capacity and LVDD, using echocardiography, were evaluated before and after the 3-month exercise program. RESULTS: At baseline, anthropometric data were similar between the groups, except for body mass index (BMI), which was higher in CONT (31 +/- 3 vs 28+/- 3 kg x m(-2); P < 0.05). There were no significant differences in glycemic control (HbA1c: 6.4 +/- 1.2 vs 5.8 +/- 1.3%; P = 0.2) or maximal oxygen uptake (26.7 +/- 5.9 vs 28.6 +/- 3.9 mL x kg(-1) x min(-1); P = 0.4) between groups. Normalization of LVDD was observed in 5 of 11 EX subjects, (P < 0.0001) of whom four had grade 1 LVDD before exercise training. No change in diastolic function was observed in the CONT group. After exercise training, maximal oxygen uptake increased in the EX group (28.6 +/- 3.9 vs 32.7 +/- 5.7 mL x kg(-1) x min(-1); P < 0.05), whereas there was no change in the CONT group (26.7 +/- 5.9 vs 27.3 +/- 6.2 mL x kg(-1) x min(-1); P = 0.58). In both groups, there was no significant change in BMI. CONCLUSIONS: Along with an improvement in exercise capacity, aerobic exercise training has the potential to reverse LVDD in patients with well-controlled, uncomplicated type 2 diabetes.     

Ventilatory response to exercise in simulated obesity by chest loading

INTRODUCTION & PURPOSE: Obesity-related increases of weight on the chest wall are known to decrease lung volume and chest wall compliance, but the effect of this mass loading, independent of other obesity-related complications on the ventilatory response to exercise is unknown. The purpose of this study was to investigate the effect of chest mass loading on the ventilatory response to exercise. METHODS: External chest loading (CL) was used to simulate the effect of moderate obesity (BMI = 32 kg x m). Eight healthy nonobese subjects performed two incremental exercise tests on a cycle ergometer with work rate increasing 25 W every 3 min once without (control; CON) and once with CL. Expiratory reserve volume (ERV), forced vital capacity (FVC), and forced expiratory volume in 1 s (FEV1) were measured before each test. During exercise, inspiratory capacity (IC), to estimate changes in end-expiratory lung volume, and inspiratory (TI) and expiratory (TE) duration, tidal volume (Vt), breathing frequency (Fb), minute ventilation (VE), mean inspiratory (Vt/TI) and expiratory (Vt/TE) flow rates, and oxygen consumption (VO2) were measured. RESULTS: Baseline ERV, FVC and FEV1 were lower with CL (P < 0.05). Compared with CON, the peak work rate achieved during exercise with CL was lower and VO2, VE, Fb, Vt/TI, and Vt/TE were higher, and Vt was lower at work rates > or = 100 W (P < 0.05). IC increased progressively in CON during exercise but remained unchanged with CL. CONCLUSION: Obesity-related chest loading decreases lung volumes and increases the mechanical ventilatory constraints during exercise and is likely a critical factor in reducing exercise capacity in obesity.     

Benefits of intrahospital exercise training after pediatric bone marrow transplantation

The purpose of this study was to determine if an eight-week intrahospital supervised, conditioning program improves functional capacity and quality of life (QOL) in children (4 boys, 4 girls) (mean [SD] age: 10.9 [2.8] years [range: 8-16]) who have undergone bone marrow transplantation (BMT) for leukemia treatment within the last 12 months. A group of 8 age and gender-matched healthy children served as controls. The experimental group performed 3 weekly sessions of resistance and aerobic training inside an intra-hospital gymnasium. A significant combined effect of group and time (p < 0.05) was observed for muscle functional capacity (Timed Up and Down Stairs [TUDS] test) and peak oxygen uptake (V.O(2peak)), i.e., with BMT children showing greater improvements than controls (V.O(2peak) at pre- and post-training of 25.9 (8.2) and 31.1 (7.6) mL/kg/min in diseased children). Muscle strength (6 RM test for bench and leg press and seated row) also improved after training (p < 0.05) in the BMT group. Concerning QOL, a significant combined effect of group and time (p < 0.05) was also observed for children's self-report of comfort and resilience and for parents' report of their children's satisfaction and achievement. In summary, children who have received BMT experience physical and overall health benefits after a relatively short-term (8 weeks) supervised exercise training program.     

Time course of improved flow-mediated dilation after short-term exercise training

PURPOSE: The purpose was to determine the influence of a unilateral localized short-term handgrip training protocol on brachial artery flow-mediated dilation (BAFMD) and to examine the time course of such changes. METHODS: Fourteen healthy males (age: 26 +/- 5.7 yr) underwent high-resolution ultrasonographic brachial artery assessments before (V1), during (V2-V7), and at the end of 4 wk (V8) of 60% maximal voluntary contraction handgrip training (20 min.d-1, 5 d.wk-1) of the nondominant arm. RESULTS: Before training resting diameters were similar between the trained (nondominant) and untrained (dominant) arms. A 2 (trained and untrained arms) x 2 (V1 and V8) repeated measure ANOVA revealed a significant main (P = 0.02 and P = 0.03) and interaction effect (P = 0.05 and P = 0.01) for the percent and absolute change in BAFMD. BAFMD improved 62% and 70%, respectively from V1 to V8, for the percent and absolute change. Subsequent linear orthogonal polynomial contrasts indicate both the percent and absolute change in BAFMD were statistically different at V2 (end of week 1 and 4 training days) from V1. These unilateral changes were not accompanied by changes in resting artery diameter, hemodynamic measures, hematological markers, and indices of heart rate variability suggesting the change may be locally mediated. CONCLUSIONS: This study shows a localized short-term exercise-training program resulted in significant improvements in BAFMD in the trained arm compared with the untrained arm and suggests this occurred after only 4 d of training.     

Reduced heart rate response to exercise in ischemic heart disease: the fallacy of the target heart rate in exercise testing

When exercise testing 159 patients with prior myocardial infarction, we identified 39 who were limited by fatigue. This group was all in sinus rhythm; none were taking drugs likely to impair the chronotropic response of the heart; none experienced chest pain or developed ischemic ECG changes. In 18 of this group, maximal heart rate achieved with exercise was 2SD or more below the age predicted value, and their heart rate response to exercise was reduced compared to that of the other 21 whose maximal exercise heart rates were within 2SD of age predicted values. A subgroup of 8 subjects with reduced exercise heart rates was studied before and after vagal blockade. In the 4 subjects whose infarction was inferior, the reduction in heart rate response was more profound and persisted after vagal blockade, suggesting either reduced pacemaker responsivness, due to ischemia or infarction, or autonomic imbalance as possible mechanisms. All 8 showed alinear increases in ventilation at higher power outputs and mean blood lactate postexercise was 7.5 mM/I without vagal blockade. Our findings suggest that a reduced heart rate response to exercise, already shown to imply added coronary risk, may be subdivided aetiologically and possibly prognostically. The use of a "Target Heart Rate" in such patients offers no safety margin, and maximal exercise capacity will be grossly over-estimated if extrapolated from the submaximal heart rate response. A cardiovascular limitation to exercise may be detected by an alinear increase in ventilation.     

Cardiorespiratory exercise training in children

Definitive statements concerning the cardiorespiratory effects of exercise training in children cannot be made. Few carefully controlled and well-defined exercise training studies including important cardiorespiratory variables have been conducted. Generally, it appears that the response to training in pubescent and postpubescent children is not different from what is observed in adults.     

Haemorheology in exercise and training

Disruption of the normal rheological properties of blood is considered an independent risk factor for cardiovascular disease and plays a significant role in the aetiology of atherothrombogenesis. The acute increase in whole blood viscosity may unfavourably affect the microcirculatory blood flow and oxygen delivery to the tissues. It is universally accepted that exercise and physical activity performed on a regular basis has health benefits. However, the effects of exercise on the rheological properties of blood have not received much research attention. Recent, limited evidence indicates that the viscosities of whole blood and plasma increase in response to a variety of exercise protocols. The increase in whole blood viscosity is mainly attributed to an increase in haematocrit and plasma viscosity, whereas the deformability and aggregability of red blood cells remain unaltered. The increases in plasma viscosity and haematocrit have been ascribed to exercise-induced haemoconcentration as a result of fluid transfer from the blood to the interstitial spaces. The haemorheological changes associated with strenuous exercise appear to be linked with enhanced oxidative stress and depletion of antioxidant capacity, and that may affect oxygen delivery and availability to the tissues.Although significant advances have been made in many areas of exercise haematology, the long-term effects of endurance training on blood rheology have been very briefly examined and the exact effect of training has not as yet been determined. Available cross-sectional and longitudinal studies indicate that the blood of endurance athletes is more dilute and this has been attributed to an expansion of blood volume, particularly plasma volume as a result of training. The low haematocrit values in trained athletes represent a hydration condition rather than iron stores deficiency. It has been suggested that this hypervolaemia and blood dilutional effect of endurance training may be advantageous for heat dissipation and greater cardiac stroke volume and lower heart rates during exercise. Enhanced blood fluidity also facilitates oxygen delivery to the exercising muscles because of a reduced resistance to blood flow within the microcirculation. Furthermore, the increase in plasma volume may contribute to the body water pool and help offset dehydration. The influence of strength and power training on blood rheology is not known. The physiological mechanisms responsible for and the functional consequences of the haemorheological changes associated with exercise to a large extent remain speculative. The paradox of haematocrit and blood rheology in exercise and training warrants additional studies. Likewise, further investigations are necessary to determine the possible link between overtraining and blood rheological profiles.