Recovery of pulmonary diffusing capacity after maximal exercise

Abstract

Pulmonary diffusing capacity (Dl_co), together with spirometric variables, arterial oxygen tension (paO₂) and cardiac output were determined before and at intervals after maximal arm cranking, treadmill running and erogmeter rowing. Independent of the type of exercise, Dl_co increased immediately post‐exercise from a median 13.6 (range 7.3–16.3) to 15.1 (9.3–19.6) mmol min^‐1 kPa^‐1 (P <0.01). However, it decreased to 11.6 (6.9–15.5) mmol min^‐1 kPa^‐1 (P <0.01) after 24 h with cardiac output and paO₂ at resting values, and Dl_co normalized after 20 h. Thoracic electrical impedance at 2.5 and 100 kHz increased slightly post‐exercise, indicating a decrease in thoracic fluid balance, and there were no echocardiographic signs of left ventricular failure at the time of the decrease in Dl_co. Also, active muscle (limb) circumference and volume, and an increase in haematocrit from 43.8 (38.0–47.0) to 47.1 (42.7–49.8) (P <0.01), had normalized at the time of the decrease in Dl_co. Vital capacity, forced vital capacity, forced expiratory volume in 1 s, peak and peak mid‐expiratory flows did not change. However, total lung capacity increased from 6.8 (5.0–7.6) to 7.0 (5.1–7.8) litres (P <0.05) immediately after exercise and remained elevated at 6.9 (5.1–8.7) litres (P <0.05) when a decrease in Dl_co was noted. The results demonstrate that independent of the type of maximal exercise, an approximate 15% reduction in Dl_co takes place 2–3 h post‐exercise, which normalizes during the following day of recovery.     

Cardiac Structure and Function in Women Basketball Athletes: Seasonal Variation and Comparisons with Nonathletic Controls

Abstract

To characterize hypertrophy and quantify seasonal changes in cardiac structure and function of women collegiate basketball (BB) athletes (n = 15), echocardiography (echo) measurements were made in the fall (FALL₁), winter (WIN), and spring (SPR), then again during the subsequent fall (FALL₂; n = 10). Comparisons were made to age-matched nonathletes (NA) measured during FALL₁ (n = 22) and SPR (n = 5). Left ventricular (LV) internal dimension–diastole (LVIDd), LV end-diastolic volume (LVEDV), stroke volume (SV), LV mass (LVM), septal thickness (IVS), LV posterior wall thickness (LVPW), right ventricular (RV) internal dimension-diastole (RVIDd), and aortic root diameter (AOD) were significantly larger (12–70%) in the athletes; RVIDd-, LVEDV-, SV-, and LVM-index were also significantly greater (8–46%). From FALL₁ to SPR measurement periods, LVWd, RVWd, LVEDV, SV, IVS, and LVM-index increased significantly (7–18%) in the athletes. Over the same period of time, LVIDd, LAD, AOD, LVEDV, and SV measured in the five NA subjects increased significantly. In the athletes, LVIDs, RVIDd, IVS, LVPW, and LVM decreased significantly (5–30%) from the SPR to FALL₂ measurement period. These data characterize the general nature of the cardiac hypertrophy noted in women BB athletes compared to NA controls and show that distinct changes in heart structure corresponding to different periods of the competitive season can occur in these athletes.     

Do the effects of high intensity 40 km cycling upon left ventricular function and cardiac biomarker during recovery vary with time of day?

Abstract

Twelve healthy participants performed two identical high-intensity 40 km cycling trials (morning and evening) under controlled laboratory conditions. Echocardiograms and venous blood samples were collected before and after each exercise bout. Cardiac electro-mechanical-delay (cEMD) was measured as QRS-complex onset to peak systolic (S’) and early diastolic (E’) tissue velocities. Myocardial strain and strain rates were assessed in longitudinal, circumferential and radial planes at the left ventricular apex and base. Cardiac troponin I (cTnI) and N-terminal Pro-Brain Natriuretic Peptide (NT-proBNP) were assessed as biomarkers of cardiomyocyte damage and wall stress. cEMD was lengthened after both morning (S’: 160 ± 30 vs. 193 ± 27; E’: 478 ± 60 vs. 620 ± 87, P < 0.05) and evening (S’: 155 ± 29 vs. 195 ± 31; E’: 488 ± 42 vs. 614 ± 61, P < 0.05) trials. A reduction in peak S’ (morning: 6.96 ± 1.12 vs. 6.66 ± 0.89; evening: 7.09 ± 0.94 vs. 7.02 ± 0.76) was correlated with cEMD (r = ?0.335, P < 0.05). Peak longitudinal strain was reduced, atrial strain rates were sporadically increased in both trials post-cycling. cTnI was elevated in only two participants (0.04 µg · L^?1, 0.03 µg · L^?1), whilst NT-proBNP was below the clinical cut-off point in all participants. Prolonged-cycling resulted in a lengthening of cEMD, small changes in aspects of left ventricular deformation and sporadic increases in cardiac biomarkers. None of these effects were moderated by time-of-day.     

Cardiac Dimensions in Elite Young Track Athletes

The purpose of the study was to compare young sprint and distance runners for changes in their cardiac dimensions with increased age (10–17 years) or body surface area (1–2 m²). Echocardiographic dimensions were obtained on 73 male track athletes competing in the 1983 National Age Group Track and Field Association championships. Each group of athletes was also compared with a hypothetical normal population (matched for weight and age) generated from prediction equations derived by Henry, Gardin, & Ware (1980). The cardiac dimensions examined were: Left ventricular internal diameter, left ventricular posterior wall thickness, and interventricular septum thickness. The male distance runners (n = 38) had a significantly greater increase in left ventricular posterior wall thickness and interventricular septum thickness with increasing age or increasing body surface area compared to the sprinters (n = 35) or compared to the predicted normal population. The left ventricular internal diameter was not significantly different between the groups. These results indicate that the hearts of male distance runners are undergoing a training hypertrophy whereas the hearts of sprinters are no different than hearts in a normal population. The changes in cardiac dimensions of these young athletes run counter to the generalizations stated for adult athletes: That endurance training enlarges the left ventricular internal diameter, but does not increase the left ventricular posterior wall or interventricular septum thickness.     

Ultrasound and cadaveric prosections as methods for teaching cardiac anatomy: a comparative study

This study compared the efficacy of two cardiac anatomy teaching modalities, ultrasound imaging and cadaveric prosections, for learning cardiac gross anatomy. One hundred and eight first-year medical students participated. Two weeks prior to the teaching intervention, students completed a pretest to assess their prior knowledge and to ensure that groups were equally randomized. Students, divided into pre-existing teaching groups, were assigned to one of two conditions; "cadaver" or "ultrasound." Those in the cadaver group received teaching on the heart using prosections, whereas the ultrasound group received teaching using live ultrasound images of the heart. Immediately after teaching, students sat a post-test. Both teaching modalities increased students' test scores by similar amounts but no significant difference was found between the two conditions, suggesting that both prosections and ultrasound are equally effective methods for teaching gross anatomy of the heart. Our data support the inclusion of either cadaveric teaching or living anatomy using ultrasound within the undergraduate anatomy curriculum, and further work is needed to compare the additive effect of the two modalities.     

钙离子电流对螺旋波的稳定性的影响

基于LuoRudy91模型研究了心脏组织中的钙离子电流对螺旋波的稳定性的影响。研究表明,通过有效减弱钙离子电流的大小,可以有效减小心肌细胞的动作电住持续时间ADP恢复曲线的斜率,从而有效地增加了心脏组织中的螺旋波的稳定性。     

铃兰提取液对蟾蜍心肌活动的影响

本文通过化学方法提取的铃兰毒甙(convallataxin)液,铃兰皂甙(convauasaponin)液作用于蟾蜍离体心脏活动,发现铃兰叶、茎、根、全草浸液,水提取液皆有强心作用.     

磁提针刺激内关穴对心功能影响的实验研究

通过观察无创性的磁提针对运动时心肌泵血功能和血液供应的变化及心脏功能的恢复作用 ,探讨其对提高心功能的可行性及其作用机理。通过对 1 5名一级以上耐力运动员和 1 5名无系统训练普通大学生超声心动图的测试 ,结果表明 :利用磁提针刺激内关穴可以激发心脏心力储备的潜力 ,提高运动中心脏的舒张机能和泵血机能 ,有助于疲劳的恢复 ,提高运动能力 ,尤其对无系统训练者效果更为明显     

耐力训练对动态心功能的影响与ACE基因多态性的关联研究

测定87名北方汉族新兵,经18周的5km跑耐力训练前后动态左心室结构与功能指标,并应用PCR-AFLP方法检测其ACE基因I/D多态,观察两者之间是否存在关联。结果显示:耐力训练后,左心室结构和功能发生了适应性改变,表现在100W负荷下,左室内径、每搏量、左室后壁、室间隔厚度的增加,反映了心脏机能的增强;相同负荷下功能指标,如射血分数、心输出量呈机能节省化下降,反映了心力储备良好;但是ACE基因型组间比较左心室结构和功能改变的差异无显著性(P>0.05)。在中国北方汉族青年中,未发现ACE基因I/D多态性与左室动态心功能指标的训练敏感性之间的关联。     

胰岛素样生长因子—l在运动性心肌肥大中的作用

IGF-1(胰岛素样生长因子-1)是目前被广泛研究和应用的一种促生长因子。它调节多种类型细胞的增殖和分化,对心肌细胞和血管平滑肌细胞的作用也受到证实。在运动性心肌肥大过程中,IGF-1作为机械刺激和基因表达的连接物发挥重要作用。