运动与心脏(下)(运动生理第九讲)

二、运动与心泵功能心脏的作用就象一个泵,而维持这个泵不停地运转有赖于心肌,故目前认为,心脏的机械功能(即心泵功能)应包括作为肌群集合体的心肌功能及作为排血功能的泵功能。50年代末和60年代初,Abbott和Sonnenblick建立的心肌力学,把心脏视为肌肉器官,研究心脏机械活动全过程中张力、长度和缩短(延长)     

心肌收缩性能对体育锻炼的适应

心肌收缩性能指心肌细胞的功能状态,是决定心脏泵血功能的内在因素。运动状态下心室搏出量能够持久而大幅度地增高,主要靠心缩性能增强而实现。因此,探讨体育锻炼对心缩性能的影响,以及心肌收缩性能对长期体育锻炼所发生的适应性变化,在运动生理学中有重要意义。     

116例高原低血压综合征血流动力学观察报告

高原低血压综合征血流动力学各项参数与正常血压人群相比都有非常显著差异(P<0.01),其中以心输出量、循环血容量减少、外周阻力增强、微循环留滞时间延长、载体血粘度加大、心泵功能减弱等指标为主,加强高原低血压综合征的检出对于预防急性高原反应及急性高原病有助,针对垂体—肾上腺素轴对血流动力学的影响,作者试用糖皮质激素、甲基睾丸素、654—2等治疗高原低血压综合征,收到良好效果。     

心脏泵血功能与无氧阈关系的探讨

作者对男性少年的无氧阈和心输出量的测定中发现,在递增负荷运动中无氧阈的出现与心输出量增加速率减少有关;心脏泵血动能是影响无氧阈的重要因素,训练可增加前者,而后者在前者增加后才得以提高。     

116例高原低血压综合征血流动力学观察报告

高原低血压综合征血流动力学各项参数与正常血压人群相比都有非常显著差异(p<0.01),其中以心输出量、循环血容量减少、外周阻力增强、微循环留滞时间延长、载体血粘度加大、心泵功能减弱等指标为主,加强高原低血压综合征的检出对于预防急性高原反应及急性高原病有助。针对垂体-肾上腺素轴对血流动力学的影响,作者试用糖皮质激素、甲基睾丸素、654—2等治疗高原低血压综合征,收到良好效果。     

运动与心脏(上)

<正> 自从1899年Henschen建立了运动心脏(Sports-heart)或运动员心脏(Aehletic heart)的概念以来,对运动与心脏的研究一直是运动生理与运动医学研究中一个重要领域。本文拟对有关运动与心脏肥大、运动与心脏泵血功能及运动心脏与病理心脏的鉴别诊断等问题加以阐述,供教练员及运动医学、运动生理学工作者参考。     

人工重力联合运动锻炼对4d头低位卧床期间心血管功能的影响

目的利用头低位卧床模拟失重模型,观察人工重力联合运动锻炼对抗短期模拟失重致心血管功能失调的作用效果。方法 12名男性受试者随机平均分为两组:对照组和对抗组。对照组仅进行4 d头低位卧床,对抗组利用SAC-Ⅱ型短臂离心机在卧床期间每天进行1 h梯度(1~2 G)人工重力联合40 W运动锻炼。所有受试者卧床前后进行立位耐力、心脏泵血与收缩功能、最大工作负荷(PWC170)、腘静脉顺应性测试。结果与卧床前相比,对照组卧床后立位耐力、心脏泵血与收缩功能、PWC170显著降低(P0.05),腘静脉横截面积及顺应性显著升高(P0.05)。对抗组上述参数在卧床前后无明显变化。结论 4 d头低位卧床可导致心脏泵血和收缩功能降低,运动耐力下降以及下肢静脉顺应性明显升高。每天1h梯度(1~2 G)人工重力联合40 W运动锻炼能够有效维持头低位卧床期间心脏泵血和收缩功能、运动耐力以及静脉顺应性。     

人工重力联合运动锻炼对4 d头低位卧床期问心血管功能的影响

目的 利用头低位卧床模拟失重模型,观察人工重力联合运动锻炼对抗短期模拟失重致心血管功能失调的作用效果.方法 12名男性受试者随机平均分为两组:对照组和对抗组.对照组仅进行4 d头低位卧床,对抗组利用SAC-Ⅱ型短臂离心机在卧床期间每天进行1 h梯度(1～2 G)人工重力联合40W运动锻炼.所有受试者卧床前后进行立位耐力、心脏泵血与收缩功能、最大工作负荷(PWC170)、胭静脉顺应性测试.结果 与卧床前相比,对照组卧床后立位耐力、心脏泵血与收缩功能、PWC170显著降低(P＜0.05),胭静脉横截面积及顺应性显著升高(P＜0.05).对抗组上述参数在卧床前后无明显变化.结论 4 d头低位卧床可导致心脏泵血和收缩功能降低,运动耐力下降以及下肢静脉顺应性明显升高.每天1 h梯度(1～2 G)人工重力联合40 W运动锻炼能够有效维持头低位卧床期间心脏泵血和收缩功能、运动耐力以及静脉顺应性.     

间歇运动训练对心脏缺血再灌注损伤大鼠心肌抗氧化酶的影响

目的:探讨间歇运动抗心脏缺血再灌注(ischemia/reperfusion,I/R)损伤的保护作用及其机制。方法:32只大鼠随机分成三组:间歇运动训练组、一次间歇运动组和对照组(假手术组和缺血再灌注对照组),缺血再灌注模型制备前,间歇运动训练组进行高强度间歇运动训练,一次间歇运动组仅进行一次高强度的间歇运动,对照组不运动。采用结扎大鼠左冠状动脉方法制备在体大鼠心肌缺血再灌注损伤模型。缺血30分钟、再灌注40分钟后检测大鼠血清心肌肌酸激酶(CK)、乳酸脱氢酶(LDH)活性,心肌抗氧化酶活性和心肌丙二醛(MDA)含量。结果:经间歇运动训练和一次间歇运动预处理的大鼠,血清CK和LDH显著低于对照组,心肌组织SOD和GSH-PX活性显著高于对照组,心肌中MDA含量显著低于对照组。结论:间歇运动训练可能通过提高缺血再灌注心肌的抗氧化能力来实现对其的保护作用。     

体外反搏对少年耐力运动员心缩间期等指标的影响

提高心脏功能的传统方法是通过运动器官的锻炼间接提高心脏的泵血机能,由于训练过程受多种因素的影响,其效果往往难尽人意。为探索提高少年耐力运动员心脏功能的辅助训练手段,我们对本市１２名少年耐力运动员进行了两个疗程的体外反搏对照试验,本文通过心缩间期的变化...     

Hypokinetic circulation in persons with paraplegia

INTRODUCTION: It is well established that hemodynamic dysfunction, resulting in diminished upper-extremity work capacity, occurs in persons with spinal cord injury (SCI) as compared with those who are nondisabled (ND). Although it has been shown that persons with paraplegia display higher values of heart rate (HR) with lower values of stroke volume (SV) during exercise, it is not resolved whether there is adequate compensation to produce similar values of cardiac output (.Q) as in ND. PURPOSE: This study examined central cardiovascular responses (HR, SV, and .Q) of 20 subjects with complete thoracic level SCI (T(4)-T(11)) and 20 sedentary ND subjects during matched levels of arm-crank (AC) exercise. METHODS: All subjects performed an incremental peak AC test to volitional exhaustion with continuous metabolic analysis and HR measurement via open circuit spirometry and 12-lead electrocardiography, respectively. Stroke volume was assessed using transthoracic impedance. RESULTS: Heart rate was higher for SCI (P< 0.05) with significantly lower values for SV and .Q at rest (approximately 25%). Peak responses were significantly higher for ND in all factors except HR. Although subpeak HRs at matched absolute workloads were significantly higher for SCI (12-20 beats.min (-1) ), SV and .Q were significantly lower (P< 0.05). CONCLUSIONS: The results of this study indicate that .Q is significantly lower in SCI than in ND during AC, despite significantly greater values of HR. These findings also suggest that the disparity in exercise values of .Q is related to differences exhibited at rest.     

Cardiovascular adjustments to exercise distributed between the upper and lower body

The present study examined the hemodynamic differences between upper- and lower-body exercise where the total power output (PO) was proportionally distributed between the upper and lower body. Six males completed five combinations of arm-leg exercise at maximal and three submaximal intensities. The ratio of arm PO to total PO for each exercise combination was 0, 25, 50, 75, and 100%. At each submaximal intensity, VO2 and cardiac output (Q) were not different (P greater than 0.05) across exercise combinations. Likewise, heart rate (HR) responses were not different for 0, 25, 50, and 75% at level 1 (mean = 102, 102, 106, 106 beats.min-1, respectively), level 2 (mean = 114, 110, 119, 118 beats.min-1, respectively), and level 3 (mean = 127, 124, 132, 131 beats.min-1, respectively). However, HR for 100% (arm-only exercise) tended to be higher than 0% at level 1 (delta HR = 10 beats.min-1; P less than 0.10), level 2 (delta HR = 12 beats.min-1, P less than 0.06) and level 3 (delta HR = 10 beats.min-1; P less than 0.06). At level 1, stroke volume (SV) remained essentially unchanged from 0-75%, while SV at 100% (108 ml) was slightly though not significantly lower (P less than 0.10) than 0% (125 ml). At exercise levels 2 and 3, SV remained unchanged for 0 and 25%; however, SV at 50, 75, and 100% were generally lower (P less than 0.05) compared with 0%. These results indicate that involving the leg musculature to varying degrees during arm-leg exercise attenuates the hemodynamic differences observed during strict upper body versus strict lower body exercise.     

NOS3 gene polymorphisms and exercise hemodynamics in postmenopausal women

We tested whether the G894T and T-786C NOS3 polymorphisms were associated with exercise cardiovascular (CV) hemodynamics in sedentary, physically active, and endurance-trained postmenopausal women. CV hemodynamic parameters including heart rate (HR), systolic (SBP) and diastolic (DBP) blood pressures and cardiac output (Q), as determined by acetylene rebreathing, stroke volume (SV), arteriovenous oxygen difference (a-vO2 diff), and total peripheral resistance (TPR) were measured during submaximal (40, 60, 80 %) and maximal (approximately 100 % VO2max) exercise. NOS3 G894T genotype was not significantly associated, either independently or interactively with habitual physical activity (PA) level, with SBP, Q, TPR, or a-vO2 diff during submaximal or maximal exercise. However, NOS3 894T non-carriers had a higher submaximal exercise HR than NOS3 894T allele carriers (120 +/- 2 vs. 112 +/- 2 beats/min, p = 0.007). NOS3 894T allele carriers had a higher SV than 894T non-carriers (78 +/- 2 vs. 72 +/- 2 ml/beat, p = 0.03) during submaximal exercise. NOS3 894T non-carriers also had a higher maximal exercise HR averaged across habitual PA groups than T allele carrier women (165 +/- 2 vs. 158 +/- 2 beats/min, p = 0.04). NOS3 894T allele carriers also tended to have a higher SV during maximal exercise than 894T non-carriers (70 +/- 2 vs. 64 +/- 2 ml/beat, p = 0.08). NOS3 T-786C genotype was not significantly associated, either independently or interactively, with any of the CV hemodynamic measures during submaximal or maximal exercise. These results suggest an association of NOS3 G894T genotype with submaximal and maximal exercise CV hemodynamic responses, especially HR, in postmenopausal women.     

Cardiovascular effects of cadence and workload

Increases in cadence may augment SV during submaximal cycling (> 65 % VO2max) via effects of increased muscle pump activity on preload. At lower workloads (45 - 65 % VO2max), SV tends to plateau, suggesting that effects of increases in cadence on pump activity have little influence on SV. We hypothesized that cadence-induced increases in CO at submaximal workloads, where SV tends to plateau, are due to elevations in HR and/or O2 extraction. SV, CO, HR, VO2, and delta a - vO2 were assessed at 80 and 100 rpm during workloads of 50 % (LO) or 65 % (HI) of VO2max in 11 male cyclists. No changes in SV were seen. CO was higher at 100 rpm in 10 of 11 subjects at LO (18.1 +/- 2.7 vs. 17.2 +/- 2.6 L/min). VO2 at both workloads was greater at 100 than 80 rpm as was HR (LO: 129 +/- 11 vs. 121 +/- 10 beats/min; HI: 146 +/- 13 vs. 139 +/- 14 beats/min) (p < 0.05). delta a - vO2 was greater at HI compared to LO at 80 (15.1 +/- 1.6 vs. 13.6 +/- 1.3 ml) and 100 rpm (16.0 +/- 1.7 vs. 15.1 +/- 1.6 ml) (p < 0.05). Results suggest that increases in O2 demand during low submaximal cycling (50 % VO2max) at high cadences are met by HR-induced increases in CO. At higher workloads (65 % VO2max), inability of higher cadences to increase CO and O2 delivery is offset by greater O2 extraction.     

Estimation of total oxygen uptake in women during exercise by total heart beats and aerobic fitness

The present study was performed to find a practical method for estimating total O2 uptake (TVO2) of women during exercise based on total heart beats (THB) and aerobic fitness level, and examine the influence of the type of exercise on the estimation. After 60 observations on 20 female subjects tested by the cycle ergometer, the following formula was derived. TVO2 (ml.kg-1) = SR125 X (61.0 X mean HR + 2543) X THB X 10(-4), where mean HR is mean heart rate (beats.min-1) in exercise, and SR125 is the slope of the regression line between accumulated heart beats and accumulated O2 uptake during exercise at 125 beats.min-1 of mean HR. SR125 was significantly correlated not only to VO2max but also each score (X) in any simple endurance tests, such as the step test for 3 min, yielding a formula, SR125 = -0.00115X + 0.3081. Both formulae indicate that the TVO2 of any exercising person can be estimated from THB and mean HR when SR125 was determined by the simple endurance test. The discrepancy between both TVO2 as estimated by our method and measured directly by the Douglas bag method during walking on a treadmill was not significant with that during the cycling on an ergometer. Accordingly, our method may possibly be used for estimating TVO2 in exercise mainly using the leg muscles such as in cycling and walking.     

Reversed drift in heart rate but increased oxygen uptake at fixed work rate during 24 h ultra‐endurance exercise

In this paper we report a reversed drift in heart rate (HR) but increased oxygen uptake (VO₂) during ultra‐endurance exercise. Nine well‐trained male athletes performed 24‐h exercise in a controlled laboratory setting, with alternating blocks of kayaking, running and cycling. Each block included 110 min of exercise and 10 min of rest, with an average work intensity of approximately 55% of respective VO_2peak. Blood samples were taken and HR and VO₂ measured every 6th hour during steady‐state cycling at fixed work rate. As assumed HR was increased at 6 h by 15 ± 6 beats/min compared with initial level (0 h). Thereafter the drift did not progress continuously, but instead unexpectedly returned toward initial values, although the plasma levels of catecholamines increased continuously during exercise. VO₂ was increased by 0.22 ± 0.15 L/min (10%) at 6 h and 0.37 ± 0.18 L/min (17%) at 12 h compared with 0 h, and thereafter remained stable. This implies an increased oxygen pulse (VO₂/HR) by approximately 10% at the last half of the 24‐h exercise compared with 0 h. Consequently, sole use of HR would give inaccurate estimates of exercise intensity and energy expenditure during endurance exercise lasting more than 6 h, and different patterns of cardiovascular drift need to be taken into account.     

Variation de la fréquence cardiaque au cours du décathlon

Objective. – The goal of this study is to evaluate the cardiac activity during exercise and recovery throughout an intermittent event such as the decathlon.Methods. – Heart rate (HR) was recorded continuously (5 s interval) using cardiofrequencemeter in 6 athletes (age: 25.0 ± 3.7 years; weight: 72 ± 5.4 kg; height: 178 ± 9.1 cm) participating to a regional decathlon championship.Results. – The races are the most demanding on a cardiovascular point of view (HR: 170–200 beats/min (bpm)). They are followed by the jumps (HR: 140–170 bpm) and the throws (HR: 110–140 bpm). Between each event, HR progressively decreases as a sign of recovery period. During the throws and the jumps, HR drops between each attempt but this drop is blunted during the pole vault and the high jump events, revealing a more intense state of stress. The night period is important for the cardiovascular recovery with a stability of HR during sleep.     

Pathophysiology of cardiac transplantation and the challenge of exercise

Heart transplantation is now currently performed in adult (A-HTR) as well as in pediatric cardiac patients (P-HTR). In A-HTR, heart denervation results in a delayed, blunted heart rate (HR) response to exercise onset, mainly sustained by the level of circulating catecholamines. At the offset of exercise HR resumes the pre-exercise level in 5-25 min, depending on the absolute work intensity. Peak HR is approximately 140 beats/min. Maximal aerobic power is 19 O2/kg x min, i.e., approximately 60% than that of healthy age-matched sedentary subjects and exercise tolerance is therefore reduced. A functional impairment at the muscle level may also be present, as suggested by the slow kinetics of the VO2 readjustment (phase II) at the onset of submaximal aerobic exercise. P-HTR generally behave as A-HTR. However, recently, in a few P-HTR a fast HR response to exercise and greater peak HR values (172 +/- 22 beats/min) were demonstrated. Maximal aerobic power of P-HTR was 32 +/- 7 ml O2/kg x min, greater than that of A-HTR, but yet approximately 60% of that of healthy age-matched controls. It may be concluded that occasionally P-HTR may resume an almost normal cardiovascular response to exercise; nevertheless, their exercise tolerance is limited, likely by functional impairment at the muscle level, whose origin is still unknown.     

心律失常运动员心输出量的研究

近年来由于训练强度不断增大,高水平运动员心律失常的发生率显著增加。本文研究资料表明,男心律失常组安静时心搏量明显大于正常组(P<0.05),而运动后心搏量降低(正常组心搏量增加),说明心律失常的运动员心脏储备能力差,心脏泵血功能降低,应予慎重对待。     

Effect of ultramarathon cycling on the heart rate in elite cyclists

OBJECTIVES: To analyse the heart rate (HR) response and estimate the ultraendurance threshold-the optimum maintainable exercise intensity of ultraendurance cycling-in ultraendurance elite cyclists competing in the Race across the Alps. METHODS: HR monitoring was performed in 10 male elite cyclists during the first Race across the Alps in 2001 (distance: 525 km; cumulative altitude difference: 12 600 m) to investigate the exercise intensity of a cycle ultramarathon and the cardiopulmonary strains involved. Four different exercise intensities were defined as percentages of maximal HR (HR(max)) as follows: recovery HR (HR(re)), <70% of HR(max); moderate aerobic HR (HR(ma)), 70-80%; intense aerobic HR (HR(ia)), 80-90%; and high intensity HR (HR(hi)), >90%. RESULTS: All athletes investigated finished the competition. The mean racing time was 27 hours and 25 minutes, and the average speed was 18.6 km/h. The mean HR(max) was 186 beats/min, and the average value of measured HRs (HR(average)) was 126 beats/min resulting in a mean HR(average)/HR(max) ratio of 0.68, which probably corresponds to the ultraendurance threshold. The athletes spent 53% (14 hours 32 minutes) of total race time within HR(re), 25% (6 hours 51 minutes) within HR(ma), 19% (5 hours 13 minutes) within HR(ia), and only 3% (49 minutes) within HR(hi), which shows the exercise intensity to be predominantly moderate (HR(re) + HR(ma) = 78% or 21 hours 23 minutes). The HR response was influenced by the course profile as well as the duration. In all subjects, exercise intensity declined significantly during the race, as indicated by a decrease in HR(average)/HR(max) of 23% from 0.86 at the start to 0.66 at the end. CONCLUSIONS: A substantial decrease (10% every 10 hours) in the HR response is a general cardiovascular feature of ultramarathon cycling, suggesting that the ultraendurance threshold lies at about 70% of HR(max) in elite ultramarathon cyclists.