Parasympathetic effects on heart rate recovery after exercise.

BACKGROUND: Exercise and its recovery period are associated with increased risk of death relative to sedentary periods. They are also accompanied by dynamic changes in autonomic tone. Little information is available regarding parasympathetic effects during high-intensity exercise and recovery. METHODS: Ten normal subjects (five women; age 33 +/- 2 years) underwent exercise testing on a bicycle ergometer. On day 1, subjects exercised to maximum tolerated workload using a graded protocol with 5 minutes at maximal workload (peak heart rate achieved 174.7 +/- 5.4 bpm). On day 2, subjects performed the identical exercise protocol as on day 1; 1 minute into the maximum exercise stage, atropine (0.04 mg/kg) was administered. Heart rate was recorded every minute during exercise, and an electrocardiogram was recorded every minute in recovery for 10 minutes. The parasympathetic effect on heart rate was defined by the difference in heart rate with and without atropine. RESULTS: The parasympathetic effect during maximal exercise was 3.4 to 6 bpm (p < .05). During recovery, a large parasympathetic effect on heart rate was noted by 1 minute (22.8 bpm; p < .0002), increased until 4 minutes, and then remained stable until 10 minutes. Despite faster heart rates with parasympathetic blockade, the P-R interval was shorter (p < .002), consistent with a significant parasympathetic effect on the atrioventricular node in recovery. Evaluation of the Q-T-R-R relationship on the 2 days demonstrated significant changes in both the slope (p < .0001) and the intercept (p < .0001), consistent with a modification of ventricular repolarization by parasympathetic tone in recovery. CONCLUSION: These data indicate that in normal subjects, parasympathetic effects persist during high-intensity exercise and are prominent in the early phases of recovery. These parasympathetic effects may play an important role in prevention of sudden cardiac death during these periods of increased risk.     

The psychophysical and heart rate relationship between treadmill and deep-water running

The relationship between ratings of perceived exertion and heart rate attained during submaximal running tests on a treadmill and during deep-water running was investigated in 12 male subjects. Heart rate and rating of perceived exertion scores analysed by analysis of covariance tested the equality of adjusted means and parallelism of the slope of this relationship. No significant difference existed between the slopes of the regression equations established for treadmill running and deep-water running. A paired t-test performed across the adjusted group mean heart rates revealed a significant difference between the two conditions. While the slope of the heart rate to rating of perceived exertion regression equations remained similar, the mean heart rate was 17 beats per minute lower in the deep-water running condition than during the treadmill run.     

个体化有氧运动对冠心病患者心率恢复及运动能力的影响

目的:探讨个体化有氧运动对心率恢复异常冠心病患者心率恢复情况及运动能力的影响,并分析两者间的相关性。方法:招募经冠状动脉造影确诊的冠心病患者行心肺运动试验(CPET),将75例心率恢复异常(试验终止1min时的心率恢复值(HRR1)≤12次/min)的患者纳入研究,并随机分为康复组(38例)和对照组(37例)。对照组进行常规药物治疗;康复组在对照组基础上加以强度为60%—85%目标心率的个体化有氧运动训练,每次40min,每周3次,共12周。所有患者研究结束后再次进行CPET评估心率恢复及运动能力情况。结果:训练前,两组患者HRR1、峰值功率(PP)、峰值摄氧量(VO2peak)、无氧阈(AT)均无显著差异(P>0.05);训练后,康复组的PP、VO2peak、AT与训练前相比,差异具有显著性(P<0.01,P<0.01,P<0.05),且优于对照组(P<0.05);在HRR1方面,康复组与训练前比较,差异具有显著性(P<0.05);但与对照组相比,差异并不显著(P>0.05),训练后,康复组有16例患者HRR1>12次/min,且PP、VO2peak与HRR1≤12次/min的患者相比,差异具有显著性(P<0.05);康复组HRR1的提高值(△HRR1)与运动能力提高水平(△VO2peak、△PP)呈显著相关性(r=0.347,P<0.05;r=0.419,P<0.01)。结论:虽然有氧运动在改善心率恢复方面并不像提高运动能力那样显著,但是有氧运动可以改善心率恢复并与运动能力的提高密切相关。     

Effect of Acu-TENS on post exercise airway resistance in healthy individuals

Transcutaneous electrical nerve stimulation on acupoints (Acu-TENS) is associated with increased exercise duration in healthy individuals and improves forced expiratory volume in 1 second (FEV₁) in those with respiratory illness. Whether a decrease in airway resistance (AR) is responsible for these respiratory system effects has not been investigated. This pilot study investigated the effect of a single session of Acu-TENS on AR in healthy people. Twenty individuals were invited to the laboratory twice, 1 week apart, to receive in random order either Acu-TENS or placebo-TENS (no electrical output from the TENS unit) over bilateral Lièquē (LU 7) and Dìnchu?n (EX-B1), for 45 minutes before and during a submaximal treadmill exercise test following the Bruce protocol. AR, FEV₁, forced vital capacity, rate of perceived exertion and heart rate variability were recorded before, immediately after and 15 minutes after exercise. Immediately after exercise the percentage decrease in AR from baseline was greater in the Acu-TENS group (?20.10 ± 4.00%) compared to the placebo-TENS group (?7.99 ± 3.43%) (p = 0.029). We conclude that the decrease in AR seen with Acu-TENS in healthy individuals could account for the immediate improvement in FEV₁. Acu-TENS may have a role in decreasing AR in patients with airflow limitation.     

Use of atropine to maintain higher heart rate after exercise during treadmill stress echocardiography.

The sensitivity of treadmill stress echocardiography (SE), which is extensively used as a noninvasive test to detect myocardial ischemia, is contingent on the rapid acquisition of 2-dimensional echocardiographic (2D) images immediately after exercise, before a substantial decrease in heart rate (HR). This test is technically challenging and needs proficient sonographers to obtain the images rapidly. This study was designed to determine whether administration of atropine at peak exercise would maintain a higher HR longer after exercise, thereby facilitating acquisition of images. Two comparable groups of patients were randomized to receive either 0.5 mg atropine intravenously (i.v.) (n = 20), or no medication (n = 19) at peak exercise. HR was significantly higher in the atropine group compared with the control group (P <.05) at 60, 90, and 120 seconds after exercise. There were no serious complications in either group. Atropine can be safely used to maintain a higher HR after exercise during SE, thus reducing the technical challenge of obtaining postexercise 2D images while HR remains elevated.     

大鼠膝关节软骨与不同强度跑台运动的影响

背景:适量的运动是维持正常关节组织形态结构及生理功能的必要条件,过度运动或制动均可导致关节软骨退变。目的:观察不同强度跑台运动对大鼠膝关节软骨的影响。方法:将18只雄性成年Wistar大鼠随机分安静组、低强度运动组、高强度运动组。6周后ELISA法测定血清基质金属蛋白酶3水平,并行蕃红-O染色、基质金属蛋白酶3与Ⅱ型胶原免疫组织化学染色及Mankin评分,反转录聚合酶链反应检测软骨基质金属蛋白酶3的mRNA表达。结果与结论:高强度运动组Mankin评分、血清及软骨中基质金属蛋白酶3表达均显著高于安静组与低强度运动组(P<0.05),基质糖氨多糖及Ⅱ型胶原含量均显著低于安静组与低强度运动组(P<0.05);低强度运动组与安静组差异无显著性意义。说明高强度运动可造成大鼠膝关节软骨退行性变,且软骨运动性损伤可能与基质金属蛋白酶3表达增强有关。     

电针联合有氧运动对冠心病患者心率及运动能力的影响

目的:观察电针联合有氧运动对冠心病患者心率恢复及运动能力的影响,并通过对心率变异性和氧化应激的检测探讨其作用机制。方法:招募确诊的冠心病患者行心肺运动试验(CPET),将120例心率恢复异常(试验终止1min时的心率恢复值(HRR1)≤12次/分)的患者纳入研究,并随机分为有氧运动组(A组)、电针组(B组)、电针联合有氧运动组(C组)、对照组(D组)。有氧运动组以强度为60%—75%最大运动能力的有氧运动训练,每次30—60min;电针组选取内关、郄门穴进行电针针刺治疗,每次留针30min;C组运动治疗方案同A组,运动治疗结束后1h进行电针治疗,电针治疗方案同B组;D组照常生活,常规治疗。各组治疗均为每周5次,共12周。所有患者在12周治疗前后,进行CPET评估心率恢复及运动能力情况,心率变异性指标(低频指标LF、高频指标HF、低高频指标比值LF/HF、正常心搏间期标准差SDNN)评估自主神经功能,静脉血中超氧化物歧化酶SOD、一氧化氮NO、脂质过氧化物LOOH含量检测评估氧化应激水平。结果:治疗前,4组患者的HRR1、峰值功率(PP)、峰值摄氧量(VO2peak)、无氧阈(AT)、心率变异性指标(LF、HF、LF/HF、SDNN)、氧化应激水平(SOD、NO、LOOH含量)均无显著差异(P0.05)。12周治疗后,心率恢复情况,C组HRR1优于A组、B组、D组(P0.05),B组HRR1优于A组、D组(P0.05),A组的HRR1优于D组(P0.05)。运动能力方面,A组、C组的PP、VO2peak、AT均优于B组、D组(P0.05),且C组的PP、VO2peak、AT优于A组但无显著性意义(P0.05),B组PP、VO2peak、AT与D组比较无显著差异(P0.05)。C组的心率变异性指标改善优于A组、B组、D组。C组的氧化应激水平改善优于A组、B组、D组。结论:与单纯有氧运动治疗或单纯电针治疗相比,二者结合的联合治疗方法可以更显著地改善患者的心率恢复情况和运动能力,同时患者的自主神经功能和氧化应激水平也得到了明显改善。     

Effect of treadmill testing and exercise training on self-efficacy in patients with heart failure.

BACKGROUND: Self-efficacy is a person's confidence in being able to successfully perform a specific activity or behavior. Self-efficacy has been shown to influence exercise capacity in patients post myocardial infarction, but has not been fully explored in patients with heart failure (HF). This study examined the impact of performance of a single treadmill exercise test and participation in a 3-month program of walking and resistance exercise on self-efficacy in HF patients. METHODS: 24 patients were randomized to either a home-based walking and resistance exercise program or usual care for 3 months. Prior to enrollment into the exercise program all participants performed a single treadmill exercise test with respiratory gas analysis. Self-efficacy questionnaires were completed at 3 time points, 1) prior to performance of an exercise treadmill test; 2) immediately after completing an exercise test; and 3) at the end of a 3-month exercise program. RESULTS: Self-efficacy for walking (p=0.07), climbing (p=0.17), lifting (p=0.73) and general activity (p=0.15) did not improve after performance of a single treadmill exercise test and usual care. However, self-efficacy for walking increased after 3 months of a walking and resistance exercise program. (p=0.04). CONCLUSIONS: The findings from this study suggest that in patients with stable mild to moderate heart failure, self-efficacy is improved with participation in a home-based walking and endurance exercise program. Self-efficacy is not enhanced by performance of a single treadmill exercise test and usual care.     

Effect of propranolol on delayed glucose recovery after insulin-induced hypoglycemia in normal and diabetic subjects

In order to evaluate the influence of beta-adrenergic blockade on recovery from insulin-induced hypoglycemia, we compared the effect of saline or propranolol infusion during concomitant hypoglycemia in normal and type I diabetic persons. The diabetic subjects were initially rendered euglycemic with a basal insulin infusion. Glucose turnover was measured using [3-3H]glucose tracer. Propranolol caused a small but significant delay in glucose recovery in normal subjects, with plasma glucose only 80% of the values seen during saline infusion 1 h after hypoglycemia (P less than 0.005). This delay was caused by a 70% reduction in the rebound glucose output, which was responsible for posthypoglycemic recovery. In the diabetic subjects, glucose recovery was significantly delayed as compared with that in normal persons, even in the absence of propranolol, and associated with reduced secretion of epinephrine and glucagon. Moreover, the addition of propranolol caused a further 50% reduction in glucose recovery such that plasma glucose remained below 50 mg/dl for 3 h. In contrast to normals, propranolol did not inhibit the already blunted rebound in glucose output. However, propranolol prevented the decline in glucose utilization that occurred when saline alone was infused. During saline infusion, glucose uptake was at basal rates by 60 min whereas, during propranolol administration, glucose uptake remained above baseline until 180 min (P less than 0.01). Thus, propranolol may interfere with glucose recovery after insulin-induced hypoglycemia in diabetic patients by blocking epinephrine's inhibition of glucose utilization whereas, in normals, propranolol's effect is largely accounted for by blockade of epinephrine-induced hepatic glucose production.     

阶段性功能锻炼对老年冠心病PCI术后心功能恢复的影响

目的分析阶段性功能锻炼对老年冠心病经皮冠状动脉介入治疗(PCI)术后心功能恢复的影响。方法选取2018年4月至2019年4月我院接收的152例老年冠心病患者作为研究对象,根据随机数字法将其分为对照组和研究组,各76例。对照组行常规护理,研究组在对照组基础上行阶段性功能锻炼干预。比较两组患者心功能指标、不良心脏事件发生情况及生活质量评分。结果护理后,两组患者LVEDD均减小,LVEF及6 min步行距离均升高,且研究组优于对照组,差异具有统计学意义(P<0.05)。随访6个月,研究组的不良心脏事件总发生率明显低于对照组,差异具有统计学意义(P<0.05)。研究组护理后的SF-36各维度评分及总分均明显高于对照组,差异具有统计学意义(P<0.05)。结论阶段性功能锻炼可有效改善老年冠心病患者PCI术后心功能,预防不良心血管事件发生,提高生活质量,值得临床推广应用。     

Influence of energy drinks and alcohol on post‐exercise heart rate recovery and heart rate variability

Background: Media have anecdotally reported that drinking energy drinks in combination with alcohol and exercise could cause sudden cardiac death. This study investigated changes in the electrocardiogram (ECG) and heart rate variability after intake of an energy drink, taken in combination with alcohol and exercise. Methods: Ten healthy volunteers (five men and five women aged 19–30) performed maximal bicycle ergometer exercise for 30 min after: (i) intake of 0·75 l of an energy drink mixed with alcohol; (ii) intake of energy drink; and, (iii) no intake of any drink. ECG was continuously recorded for analysis of heart rate variability and heart rate recovery. Results: No subject developed any clinically significant arrhythmias. Post‐exercise recovery in heart rate and heart rate variability was slower after the subjects consumed energy drink and alcohol before exercise, than after exercise alone. Conclusion: The healthy subjects developed blunted cardiac autonomic modulation after exercising when they had consumed energy drinks mixed with alcohol. Although they did not develop any significant arrhythmia, individuals predisposed to arrhythmia by congenital or other rhythm disorders could have an increased risk for malignant cardiac arrhythmia in similar situations.     

有氧运动对老年高血压患者心率变异性的影响

心率变异性是反映体内交感神经、迷走神经活动的方法，在临床上已得到广泛的应用。原发性高血压患者心率变异性减低，从而发生心血管事件几率及猝死的危险性增大。因此，增加原发性高血压患者心率变异性，具有重要意义。有报道有氧运动可使正常老年人心率变异性增高，亦有报道抗高血压药物对高血压患者心率变异性有影响，本研究主要探讨有氧运动联合抗高血压药物对原发性高血压患者心率变异性的影响及其临床意义，为老年高血压的治疗和愈后提供有价值的临床指标。     

Sudden intense exercise increases QT heart rate slope and T wave complexity in long QT syndrome and normal subjects

Sudden intense physical activity is a trigger for ventricular arrhythmias in long QT syndrome (LQTS), and beta-blockers (B) reduce the risk of ventricular arrhythmias in LQTS. We compared the effect of graded (gradual intensity) versus burst (sudden intensity) exercise on QT-rate adaptation and T wave complexity in LQTS + B (n = 21), LQTS - B (n = 5), and normal controls (n = 20). Graded exercise consisted of symptom-limited bicycle ergometry (30 W, increment 20 W/min). Burst exercise involved a fixed 200 W load for 1.0 minute. ECGs were digitally recorded every 10 seconds during exercise and a 10 minute recovery period. QT-rate adaptation was quantified using the slope of the QT cycle length relationship fit to a quadratic function. Principle component analysis (PCA) was used to quantify T wave complexity. The QT-rate slope was two-fold greater with burst exercise than graded exercise for LQTS + B (-82E +/- 40E vs -36E +/- 40E, P = 0.0016), LQTS - B (-85E +/- 60E vs -30E +/- 50E, P = 0.011) and controls (-100E +/- 60E vs -48E +/- 100E, P = 0.0011) (E = x10(-5)). For each exercise protocol, there was no difference in QT-rate slope between the three groups. In contrast, the QT-rate slope during the 10 minute recovery period was similar between the burst and graded protocol for LQTS + B (25E +/- 40E vs 30E +/- 50E), LQTS - B (81E +/- 80E vs 85E +/- 70E) and controls (90E +/- 80E vs 82E +/- 80E). The coefficient of variability of PCA (T wave complexity variability) during burst exercise was greater than that during graded exercise for LQTS + B (41 +/- 15 vs 30 +/- 10, P = 0.017), LQTS - B (47 +/- 25 vs 26 +/- 4, P = 0.016), and control (46 +/- 14 vs 33 +/- 19, P = 0.012). For each exercise protocol, no difference in T wave complexity variability was seen between the three groups. In conclusion, QT heart rate slope and T wave complexity variability are greater during sudden intense exercise than graded exercise in LQTS patients (on and off beta-blockers) and normal subjects, with similar findings among the three groups of patients.     

Decreased exercise heart rate and blood pressure response in diabetic subjects with cardiac autonomic neuropathy

Abnormal hemodynamic responses to exercise have been observed in diabetic subjects, but the pathogenesis and significance remain uncertain. We used maximal treadmill exercise to study 32 subjects with long-term insulin-dependent diabetes without clinical evidence of cardiac disease. Two of the 32 had occult ischemic heart disease revealed by stress electrocardiography and myocardial-perfusion scintigraphy and were excluded from subsequent analysis. In the remaining 30 subjects, we compared the responses to exercise of the 17 subjects with cardiac autonomic neuropathy diagnosed by noninvasive maneuvers (group 1) with the 13 without (group 2). At rest, the pressure-rate product (PRP) was higher in group 1 (114.0 +/- 5.7 vs. 95.9 +/- 5.3, P less than .05). With maximal exercise the increase in heart rate (44.6 +/- 4.8 vs. 79.0 +/- 5.4 beats/min, P less than .001), systolic blood pressure (36.8 +/- 5.9 vs. 55.0 +/- 5.8 mmHg, P = .02), and the PRP (102.0 +/- 7.3 vs. 182.0 +/- 8.2, P less than .001) were all lower in group 1 than in group 2, despite similar total treadmill times (631 +/- 47 vs. 587 +/- 40 s, P greater than .1). At each stage of exercise, the increase in heart rate and systolic blood pressure was lower in group 1 patients. The severity of cardiac autonomic neuropathy correlated inversely with the maximal increase in heart rate (r = -.68, P less than .001) and the PRP (r = -.58, P less than .005). Age, duration of diabetes, and the presence and severity of microvascular disease did not correlate with any of the hemodynamic parameters.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of cardiac rehabilitation on recovery of heart rate over one minute after exercise in patients with coronary artery bypass graft surgery

OBJECTIVE: To evaluate the effects of cardiac rehabilitation on the recovery of heart rate over 1 min after peak exercise of patients who received coronary artery bypass graft (CABG) surgery. DESIGN: Thirty subjects who received CABG surgery were randomly assigned to enter or not enter a cardiac rehabilitation exercise programme (cardiac rehabilitation n = 15; control group n = 15). SETTING: Outpatient cardiac rehabilitation centre in a national medical hospital. INTERVENTIONS: Patients assigned to the cardiac rehabilitation group received 36 sessions of the exercise programme, three times a week, with the intensity designed to achieve an individual 60-85% peak heart rate in cardiopulmonary exercise test. Patients assigned to the control group did not get further advice about a specific exercise programme. MAIN OUTCOME MEASURES: Resting heart rate and recovery of heart rate over 1 min after a peak exercise test at discharge and three months later were collected. The heart rates were analysed with computer-recorded electrocardiogram. RESULTS: At follow-up, the 15 patients in the cardiac rehabilitation group had a significantly lower resting heart rate (77.46+/-9.49 versus 92.31+/-10.18 bpm; p<0.001) and a significantly higher recovery of heart rate over 1 min (16.38+/-6.32 versus 11.38+4.81 bpm; p = 0.03) compared with the control group. There were also significant reductions in resting heart rates (cardiac rehabilitation p < 0.001; control p = 0.05) and improvements in recovery on heart rate over 1 min (cardiac rehabilitation p < 0.001; control p = 0.001) compared with baseline measurements in both the cardiac rehabilitation and control groups. CONCLUSION: Cardiac rehabilitation had a positive effect on the improvement of recovery on heart rate over 1 min in patients with coronary artery disease who received CABG surgery.     

Muscle glycogen concentration during recovery after prolonged severe exercise in fasting subjects

The influence of 12 h of fasting after prolonged severe exercise on the muscle glycogen concentration was studied in 5 normal subjects. The subjects exercised in the post absorptive state at 70% of max. V_o2 till exhaustion, then rested for 12 h. No food was allowed during recovery. Blood samples and muscle biopsies were obtained before exercise, immediately after the cessation of exercise, and after 2, 4, 6, 9 and 12 h of recovery. Muscle glycogen content decreased from 70.4 ± 3.0 to 21.6 ±3.9 mmol glucosyl units/kg w.w. in response to exercise. After 4 h of recovery muscle glycogen had increased to 28.8 + 3.6 mmol glucosyl units/kg (P<0.025). During the next 8 h of recovery no further increase in glycogen concentration was observed. Mean plasma glucose concentration decreased from 5.25±0.16 to 4.37±0.18 mmol/1 during exercise (P<0.001). No change in the plasma glucose level was observed during recovery. Immunoreactive insulin (IRI) concentration decreased from 15.9±1.0 to 10.2±0.5 μU/ml (P<0.001) during exercise, and remained at this level during recovery. It is concluded that some muscle glycogen repletion may occur after prolonged, severe exercise even under fasting conditions. It is suggested that this may proceed through an increased hepatic gluconeogenesis.     

Effects of exercise training on heart rate variability after coronary angioplasty

BACKGROUND AND PURPOSE: Cardiac autonomic dysfunction is associated with risk of restenosis and cardiovascular mortality in patients after percutaneous transluminal coronary angioplasty (PTCA). Analysis of heart rate variability (HRV) is an important, widely used method for assessing cardiac autonomic regulation. The purpose of this study was to investigate the effect of exercise training on HRV in subjects after PTCA. SUBJECTS AND METHODS: A total of 84 subjects who had undergone PTCA were recruited for this study. The subjects (age [mean+/-SD]=57.0+/-9.3 years) were randomly assigned to either an exercise group to undergo an 8-week outpatient exercise program or a control group to undergo usual care. Heart rate variability was measured for 5 minutes in the supine resting position at baseline and at the end of 8 weeks. RESULTS: The parasympathetically modulated HRV of the subjects in the exercise group increased significantly compared with the HRV of subjects in the control group. The effects of training on HRV were independent of angioplasty type (balloon or stent) and were unrelated to whether the subjects had received previous PTCA. DISCUSSION AND CONCLUSION: Exercise training can increase parasympathetic modulation of cardiac function in people after they have undergone successful PTCA. Our results suggest that analysis of HRV can be extended to assess the effect of exercise training on cardiac autonomic dysfunction in people after coronary angioplasty.     

Effect of treadmill exercise training on spatial and temporal gait parameters in subjects with chronic stroke: a preliminary report

The effects of task-repetitive locomotor training on stroke patients' spatial and temporal gait parameters during unassisted walking are not well understood. This study determined the effects of treadmill aerobic exercise (T-EX) on spatial and temporal gait parameters that underlie changes in overground walking function. Thirty-nine subjects with hemiparetic stroke underwent T-EX three times weekly for 6 months. We measured the subjects pre- and posttraining on 30-foot timed walks and 6-minute distance walks with usual assistive devices and on an 8 m instrumented walkway without assistive devices. T-EX improved 30-foot walks by 17% and 6-minute walks by 23%. Unassisted walking velocity increased 22%, stride length increased 13%, and cadence increased 7%. Paretic and nonparetic step lengths increased significantly, and respective step times decreased significantly. Interlimb symmetry did not change. This study presents preliminary evidence that changes in spatial and temporal gait parameters contribute to the increased velocity of subjects with stroke after T-EX.