Maximal accumulated oxygen deficit must be calculated using 10-min time periods.

PURPOSE: The accumulated O2, calculated by an extrapolation procedure from measurements of the O2 uptake at moderate powers, has been suggested as a measure of the anaerobic energy release during high intensity exercise. While some suggest that repeated 10-min bouts are required to establish the relationships in question, other use bouts of shorter durations. The purpose of this study was to examine how different exercise durations influence the calculated accumulated O2 deficit. METHODS: Eight endurance trained male cyclists with the following characteristics (Mean +/- SE): age, 25 +/- 3 yr; weight, 69.9 +/- 1.7 kg: height, 178.2 +/- 1.0 cm; and VO2max 57.5 +/- 2.4 mL x kg(-1) x min(-1) volunteered for participation in this study. The O2 uptake was measured at 2-4, 4-6, 6-8, and 8-10 min of exercise at ten different constant powers. These O2 uptakes were used to establish four relationships between the power and O2 demand for each subject. On a separate day the subjects cycled at a power of 336 +/- 42 W (corresponding to about 110% of the maximal O2 uptake) for 296 +/- 43 s to exhaustion while the O2 uptake was measured continuously. For each subject the accumulated O2 deficit was determined from the different relationships. RESULTS: The accumulated O2 deficit determined from the relationships from the 2 to 4-min exercises in the pretests were significantly less than the value calculated from the relationships obtained after the 8-10 min of exercise at constant power, the values being 39.6 +/- 11.6 mL O2 eq x kg(-1) and 53.4 +/- 14.6 mL O2 eq x kg(-1), respectively. CONCLUSIONS: This study suggests that reducing the exercise duration used in the pretests to establish the relationships between power and O2 demand from 10 min may lead to a too low accumulated O2 deficit.     

Re-assessing accumulated oxygen deficit in middle-distance runners

The purpose of this study was to re-assess the accumulated oxygen deficit (AOD), incorporating recent methodological improvements i.e., 4 min submaximal tests spread above and below the lactate threshold (LT). We Investigated the Influence of the VO2 -speed regression, on the precision of the estimated total energy demand and AOD. utilising different numbers of regression points and including measurement errors. Seven trained middle-distance runners (mean +/- SD age: 25.3 +/- 5.4y, mass: 73.7 +/- 4.3kg. VO2max 64.4 +/- 6.1 mL x kg(-1) x min(-1)) completed a VO2max, LT, 10 x 4 min exercise tests (above and below LT) and high-intensity exhaustive tests. The VO2 -speed regression was developed using 10 submaximal points and a forced y-intercept value. The average precision (measured as the width of 95% confidence Interval) for the estimated total energy demand using this regression was 7.8mL O2 Eq x kg(-1) x min(-1). There was a two-fold decrease in precision of estimated total energy demand with the Inclusion of measurement errors from the metabolic system. The mean AOD value was 43.3 mL O2 Eq x kg(-1) (upper and lower 95% CI 32.1 and 54.5mL o2 Eq x kg(-1) respectively). Converting the 95% CI for estimated total energy demand to AOD or including maximum possible measurement errors amplified the error associated with the estimated total energy demand. No significant difference in AOD variables were found, using 10,4 or 2 regression points with a forced y-intercept. For practical purposes we recommend the use of 4 submaximal values with a y-intercept. Using 95% CIs and calculating error highlighted possible error in estimating AOD. Without accurate data collection, increased variability could decrease the accuracy of the AOD as shown by a 95% CI of the AOD.     

Maximal accumulated oxygen deficit is influenced by chronological age and is related to intensity of VO2PEAK

Sport Sciences for Health - This study aimed to verify the influence of chronological age on maximal accumulated oxygen deficit (MAOD) and the correlations with maximal oxygen uptake (VO2PEAK) and...     

他汀类药物对慢性心力衰竭的疗效

 目的 观察他汀类药物在慢性心力衰竭(chronic heart failure,CHF)患者中的应用疗效。方法 选取100例CHF患者,纽约心功能(NYHA)分级Ⅱ至Ⅳ级,左室射血分数(LVEF )≤50%,按照是否使用他汀类药物分为观察组和对照组,每组各50例。观察并比较治疗前后两组左室舒张末内径(LVEDD)、左室收缩末内径(LVESD)、LVEF、C反应蛋白(CRP)、低密度脂蛋白胆固醇(LDL-C)及N末端脑利钠肽前体(NT-proBNP)水平的变化及1年内住院次数及病死率。结果 观察组使用他汀药物治疗后LVESD低于对照组[(50.12±4.67)mm vs (54.89±4.53)mm],LVEDD低于对照组[(65.31±3.82)mm vs (68.59±4.58)mm],LVEF高于对照组[(49.52±4.52)% vs (44.21±5.42)%],差异均有统计学意义(P<0.05)。与治疗前比较,观察组治疗后CRP、LDL-C及NT-proBNP降低(P＜0.05),而对照组无统计学差异。1年内观察组住院次数及病死率均低于对照组,差异有统计学意义(P＜0.05)。结论 以心血管疾病为基础疾病的CHF患者长期使用他汀类药物可明显获益。     

Effect of training on accumulated oxygen deficit and shuttle run performance

BACKGROUND: The purpose of the present study was to investigate changes in physiological, metabolic and performance parameters resulting from an intense 6 week training programme. METHODS: Sixteen volunteers were divided into a control (CN; 4 men and 2 women) and training group (TR; 6 men and 4 women). Laboratory measures included maximal aerobic power (VO2max), submaximal oxygen uptake (10.5 percent or 6 degrees treadmill inclination) and accumulated oxygen deficit (AOD). Performance was assessed during 20 metre shuttle run tests (PST, progressive shuttle run test; HIST, high intensity shuttle run test). RESULTS: TR improved their HIST performance (m) significantly compared with CN, identified by a significant "group-by-training" interaction (p<0.01). Similarly, AOD values improved more in TR compared with CN (p<0.01). There was a trend for TR to further reduce blood pH values after training compared with CN, although this decrease (approximately 0.05 units) did not attain statistical significance. The change in AOD was strongly correlated with the change in run time to exhaustion (r=0.76, p<0.01) and the change in estimated total work output (r=0.69, p<0.01) during 10.5 percent gradient running and modestly correlated with the change in HIST performance (r=0.49, p<0.05, assuming a directional test). CONCLUSIONS: The results of the present study suggest changes in the anaerobic capacity, determined as AOD, due to training may be reflected in corresponding changes in laboratory and field performance.     

The maximally accumulated oxygen deficit as an indicator of anaerobic capacity

Recently, a procedure has been established for the determination of the maximally accumulated oxygen deficit (MAOD) (Medbo et al., J. Appl. Physiol. 64:50-60, 1988) as an indicator of anaerobic capacity. We hypothesized that, if MAOD were a valid indicator of anaerobic capacity, it should distinguish between aerobically and anaerobically trained athletes and correlate with other existing anaerobic testing measures. Subjects were four distance and five middle distance runners, three sprinters, and four controls. The subjects ran for 2-3 min at 125-140% of VO2max until exhaustion, and the accumulated O2 deficit for that run was calculated by an extrapolation procedure. Subjects also performed the Wingate cycle ergometer test and runs of 300, 400, and 600 m. (Only athletes performed the runs.) Post-exercise blood lactates were obtained following the supramaximal treadmill run. MAOD (in O2 equivalents-ml.kg-1) was higher for the sprinters (78) and middle distance runners (74) than for the long distance runners (56) and control subjects (56) (P less than or equal to 0.05), indicating a greater anaerobic capacity for the former two groups. Consequently, the relative anaerobic contribution was larger for the sprinters (39%) and middle distance runners (37%) than for the long distance runners (30%; P less than or equal to 0.05). Significant correlations were found between MAOD and both Wingate power and treadmill work for all subjects and between Wingate power, Wingate capacity, treadmill work, and 300 m time for the athletes, suggesting that relationships do exist among MAOD and other anaerobic test measures. Potential use of MAOD as an indicator of anaerobic capacity is therefore promising and should be further explored.     

卡维地洛治疗慢性心力衰竭44例

卡维地洛是一种无内在拟交感活性的非选择性的第三代β受体阻滞剂,同时具有α受体的阻滞作用,笔者于2005年1月～2006年1月对卡维地洛治疗慢性心力衰竭进行了临床观察。     

慢性心力衰竭与高尿酸血症关系探讨

目的探讨慢性心力衰竭（chronic heart failure,CHF）患者心功能和血尿酸（uric acid,UA）水平及左室重构程度的关系。方法 236例CHF患者,按NYHA心功能分级分为Ⅱ、Ⅲ、Ⅳ级,分为3组,分别为78、86、72例;按UA水平分为正常血尿酸组（132例）和高尿酸血症组（104例）。所有入选者入院后急诊或常规检查尿酸、肝肾功能、电解质等项目;超声心动图测定心脏左室舒张末期内径（left ventricular end diastolic diameter,LVEDd）、左室后壁厚度（left ventricular posterior wall diameter,LVPWd）,计算左室射血分数（left ventricular ejection fraction,LVEF）。结果心力衰竭患者血尿酸明显升高,发生率为44.1%,随着心功能损害的加重,高尿酸血症的发生率增加（χ2=8.46,P〈0.05）,尿酸水平增高（F=11.68,P〈0.05）;血尿酸增高者左室舒张末内径明显增大,左室射血分数显著降低,（P〈0.05）,相关分析显示LVEDd与血尿酸水平正相关（r=0.386,P〈0.01）,LVEF与血尿酸水平负相关（r=-0.324,P〈0.05）。（F=11.68,P〈0.05）。结论随着心力衰竭程度的加重,尿酸水平逐步升高。     

Anaerobic contribution during maximal anaerobic running test: correlation with maximal accumulated oxygen deficit

The aims of this study were: (i) to measure energy system contributions in maximal anaerobic running test (MART); and (ii) to verify any correlation between MART and maximal accumulated oxygen deficit (MAOD). Eleven members of the armed forces were recruited for this study. Participants performed MART and MAOD, both accomplished on a treadmill. MART consisted of intermittent exercise, 20 s effort with 100 s recovery, after each spell of effort exercise. Energy system contributions by MART were also determined by excess post-exercise oxygen consumption, lactate response, and oxygen uptake measurements. MAOD was determined by five submaximal intensities and one supramaximal intensity exercises corresponding to 120% at maximal oxygen uptake intensity. Energy system contributions were 65.4±1.1% to aerobic; 29.5±1.1% to anaerobic a-lactic; and 5.1±0.5% to anaerobic lactic system throughout the whole test, while only during effort periods the anaerobic contribution corresponded to 73.5±1.0%. Maximal power found in MART corresponded to 111.25±1.33 mL/kg/min but did not significantly correlate with MAOD (4.69±0.30 L and 70.85±4.73 mL/kg). We concluded that the anaerobic a-lactic system is the main energy system in MART efforts and this test did not significantly correlate to MAOD.     

托伐普坦治疗慢性心力衰竭的疗效及安全性

 目的 探讨托伐普坦治疗慢性心力衰竭(chronic heart failure,CHF)患者的疗效及安全性。方法 将60例CHF患者随机分为对照组与观察组,每组30例。对照组给予常规抗心力衰竭治疗,观察组在对照组基础上加用托伐普坦治疗。于治疗前、治疗后7 d检测24 h尿量、血钠、血钾、尿素氮、肌酐、尿酸、B型利钠肽(BNP)、左室射血分数(LVEF)并评价疗效。结果 治疗7 d 后,与治疗前相比,两组患者24 h尿量、血钠明显改善,BNP下降,差异有统计学意义(P<0.05)。与对照组治疗后比较,观察组尿素氮、肌酐明显下降,LVEF明显升高,差异有统计学意义(P<0.05);但尿酸、血钾未见明显变化。观察组总有效率(90.0%)高于对照组(63.3%),差异有统计学意义(P<0.05);两组不良反应发生率比较,差异无统计学意义(P>0.05)。结论 托伐普坦可有效改善CHF患者临床症状,纠正低钠血症,改善心肾功能,且不会引起电解质紊乱,不良反应少。     

Norepinephrine alters exercise oxygen consumption in heart failure patients

PURPOSE: The primary aim of this research was to evaluate the effect of acute norepinephrine (NE) infusion on the exercise oxygen utilization in heart failure patients as compared with healthy adults. METHODS: Eleven healthy adults and 10 patients with NYHA class II-III heart failure (ejection fraction <40%) who were not on beta-blocker therapy underwent steady state exercise under placebo or NE infusion conditions, followed by maximal ramp exercise testing. Oxygen utilization, hemodynamic responses, and serum lactate NE levels were evaluated. RESULTS: The hemodynamic effects of NE were evident in both groups with statistically significant increases in blood pressure and concomitant decreases in heart rates. Lactate levels were higher in heart failure subjects under all conditions and steady state exercise increased levels by 24% (P = 0.04). NE infusion increased lactate levels by a nonsignificant 24% (P = 0.19). NE infusion tended to increase oxygen consumption (VO2) at the end of steady state exercise in CHF subjects (4% change; P = 0.06). Compared with healthy adults, NE infusion significantly impaired (increased) the gross VO2/W relationship in heart failure subjects (P = 0.037). There was also a modest trend for a worsening (decrease) in net efficiency after NE infusion in CHF subjects. There were no significant adverse effects of low-dose NE infusion in either group. CONCLUSIONS: We conclude that 1) acute low-dose NE infusion impairs the oxygen utilization in stable heart failure patients but not in healthy adults. This may help to explain the exercise intolerance that accompanies congestive heart failure. 2) Acute infusion of low-dose NE infusion is safe and well tolerated in both healthy adults and compensated heart failure patients.     

慢性心力衰竭患者心率震荡现象的变化及其意义

目的探讨慢性心力衰竭(CHF)患者心率震荡(HRT)现象的特征,及其与左室射血分数(LVEF),心率变异性(HRV)等的相关性。方法选择心衰患者58名(心衰组)和非心衰患者65名(对照组),从动态心电图和超声心动图获得HRT、HRV、左室舒张末期内径(LVEDD)、LVEF等指标,并对这些指标进行分析。结果心衰组和对照组的HRT、HRV、LVEF、LVEDD、QT间期离散度(QTcd)、平均心率有显著统计学差异,而24 h室性期前收缩的数量没有统计学意义。HRT与LVEF、LVEDD、SDNN等指标呈相关关系。结论心衰组患者HRT减弱,HRT可以反映心脏自主神经功能的状态。     

B型利钠肽与老年慢性心力衰竭的相关性研究

目的：研究B型利钠肽（BNP）在老年慢性心力衰竭（CHF）患者的诊断、评估等方面的临床价值。方法：选取2008年6月-2009年1月住院的160例60岁以上老年慢性心力衰竭患者（CHF组）,将他们按NYHA心功能分级分为4组,采用酶联免疫吸附法（ELISA）测定患者血浆BNP水平,分析BNP水平与患者心功能状态的关系。结果：各组患者血浆BNP水平分别为：Ⅰ级心功（23．2&#177;8．71）pg／ml、Ⅱ级心功（87．38&#177;36．13）pg／ml、Ⅲ级心功（599．65&#177;72．48）pg／ml、Ⅳ级心功（1184．59&#177;92．32）pg／ml,血浆BNP水平随着NHYA心功能分级的增加而显著升高,并且随年龄增大而增加,差异均具有统计学意义。结论：老年CHF患者血浆BNP水平随着心力衰竭严重程度的增加而升高,BNP可作为一种简便、有效、快速的标志物用于老年CHF的诊断及危险分层。     

Peripheral limitations of maximal aerobic capacity in patients with chronic heart failure

Conclusions  Exercise intolerance in patients with CHF is related to chronic changes in structure and function of the heart and vessels, which lead to reduction of cardiac output reserve and hypoperfusion of skeletal muscle during exercise. Chronic neurohormonal activation, endothelial dysfunction, and deconditioning may contribute to the abnormalities of skeletal muscle blood flow, function, and metabolism in patients with CHF. A combination of pharmacologic (neurohormonal blockade) and nonpharmacologic therapy (physical training) may provide the optimal regimen to improve functional capacity in patients with CHF. Therapies that increase skeletal muscle perfusion are associated with concomitant increases in peak aerobic capacity. The Xe-133 clearance method for measurement of skeletal muscle blood flow is the only noninvasive technique that allows measurement of blood flow during maximal treadmill or bicycle exercise. If skeletal muscle blood flow measurements are performed in accordance with the fundamental principles of the technique, with recognition of the method limitations and appropriate controls for sources of experimental error, the Xe-133 technique appears to be a useful tool for measurement of skeletal muscle blood flow in clinical investigations. Measurement of skeletal muscle blood flow with PET and O-15—labeled water is a promising tool for investigation of heterogeneity of blood flow within the skeletal muscle circulation, although the need for arterial blood sampling limits its application for serial measurements in response to therapy.     

Maximal oxygen intake estimated from submaximal heart rate.

This study investigated the predictability of maximal oxygen intake from three different submaximal heart rates assessed during an initial and follow-up ride on a cycle ergometer. Twenty-four healthy male subjects performed workloads of 600, 750, and 900 kpm's for six minutes on each of two visits to the laboratory. Analysis of variance for a randomised complete blocks design, with subjects constituting blocks, was used to analyse heart rate, estimated maximal oxygen intake, and residual estimated maximal oxygen intake variations among the experimental conditions. Relationships between the actual and estimated maximal oxygen intakes were determined using the Pearson Product-Moment formula of correlation. The average estimated maximal oxygen intake was significantly increased from the first testing occasion to the second. Although errors of estimation decreased significantly (450 ml to 366 ml) in favour of the second testing condition, the decrease was neither consistent with workloads nor subjects. The correlation coefficients were consistently low at 600 kpm for both testing occasions (0.68 and 0.73, respectively), consistently high at 750 kpm (0.82 and 0.84, respectively), and quite variable at 900 kpm (0.71 and 0.84, respectively), indicated that the validity of the nomogram was not consistent with all workloads or testing occasions. Despite these inconsistencies, the nomogram is, for practical purposes, a valid predictor of maximal oxygen consumption.     

小剂量螺内酯联合卡维地洛治疗慢性心力衰竭的疗效观察

 目的 探讨小剂量螺内酯联合卡维地洛治疗慢性心力衰竭(CHF)患者的临床疗效.方法 将136例CHF患者随机分为两组,每组68例,两组均使用常规治疗,观察组再加用小剂量螺内酯和卡维地洛治疗,随访10个月,评估心功能分级变化,超声心动图测量左室舒张末期内径(LVDD),左室收缩末期内径(LVSD),左室射血分数(LVEF),每搏输出量(SV),心脏指数(CI).结果 (1)两组治疗后均有效,观察组心功能改善显著,总有效率明显优于对照组(92.5% VS 73.5%,P＜0.05),(2)观察组超声心动图测量的各项指标变化显著.结论 CHF患者长期使用小剂量螺内酯和卡维地洛有益于改善心功能,提高生活质量.     

Maximal accumulated oxygen deficit and blood responses of ammonia, lactate and pH after anaerobic test: a comparison between international and national elite karate athletes

The purpose of this study was to compare maximal accumulated oxygen deficit (MAOD) and the time course of blood markers of the anaerobic metabolism in response to exhaustive supramaximal test in two elite (international vs. national) class karate athletes. Ten male international competitors from the French national team (Int, age 21.2 +/- 3.1 years, 71.9 +/- 11.4 kg) and eight national class (Nat, 23.7 +/- 2.4 years, 70.7 +/- 12.2 kg) athletes with a similar maximal oxygen uptake of 57.6 and 59.4 ml . kg (-1) . min (-1), respectively, were involved in this study. The MAOD was determined after an exhaustive supramaximal exercise (2 - 3 min at 140 % of their VO2max velocity) on a treadmill ergometer. Blood lactate, pH and plasma ammonia were determined at rest, immediately at the end of exercise and during the recovery period at 2, 4, 6, 8, 10 and 15 min. After the supramaximal exercise, a dramatic higher increase in the blood concentration of ammonia until its peak was observed in the Nat compared with the Int. Time course of [NH4+] and [La] reveals significant (p < 0.01) differences between the two groups. Peak values for [H+] (89.2 +/- 6.7 vs. 75.9 +/- 8.8 nmol . l (-1); p < 0.01), [NH4+] (180 +/- 67.9 vs. 118.7 +/- 22.7 micromol . l (-1); p < 0.05) and [La] (20.7 +/- 2.7 vs. 17.9 +/- 1.1 mmol.l (-1); p < 0.05) were higher in Nat compared with Int group, respectively. However, the MAOD was similar in both groups (67.8 +/- 8 ml . kg (-1) and 64.5 +/- 6.4 for Int and Nat groups, respectively). These data suggest that ammonia and lactate accumulation are sensitive to the level of performance in karate. Higher concentrations of these metabolites in blood after supramaximal exhaustive exercise may be related to either higher anaerobic contribution to energy supply in Nat or higher removal ability in the Int group.     

冠心病慢性心力衰竭患者尿中性粒细胞明胶酶相关脂质运载蛋白的水平及其临床意义

 目的 探讨冠心病慢性心力衰竭患者尿中性粒细胞明胶酶相关脂质运载蛋白(neutrophil gelatinase-associated lipocalin,NGAL)水平变化及临床意义。方法 收集2014-09至2015-04在武警后勤学院附属医院心脏中心就诊的冠心病慢性心力衰竭患者90例,依据NYHA(纽约心脏协会)心功能分级分为Ⅰ级组、Ⅱ级组、Ⅲ～Ⅳ级组,每组30例,健康对照组(30例)。检测各组尿NGAL及血清肌酐(serum creatinine,Scr)、血清N末端B型脑钠肽前体(N-terminal pro-B-type natriuretic peptide,NT-proBNP)水平,测量患者左心室舒张末期内径(left ventricular end-diastolic dimension,LVEDD)、 左室射血分数(left ventricular ejection fraction,LVEF),并分析各组不同指标的水平变化及临床意义。结果 健康对照组,NYHAⅠ级、Ⅱ级、Ⅲ～Ⅳ级组尿NGAL水平随着心力衰竭程度加重(NYHA分级、LVEDD增加、LVEF值下降、NT-proBNP升高)而升高,以NYHAⅢ-Ⅳ级组升高最为明显(P＜0.01);与健康对照组比较NYHAⅡ级组尿NGAL水平即有所升高,具有统计学意义(P＜0.05),而Scr水平较健康对照组变化,差异无统计学意义。结论 冠心病慢性心力衰竭患者尿NGAL水平升高出现于Scr之前,提示尿NGAL是诊断冠心病心力衰竭患者早期肾损害敏感而准确的指标之一。     

心脏再同步治疗对慢性心力衰竭患者的近期疗效观察

目的:观察心脏再同步起搏治疗对慢性心力衰竭的临床疗效.方法:31例慢性心力衰竭合并室内传导阻滞患者行心脏再同步起搏治疗,全部患者成功经冠状静脉植入左心室导线,分别于3月和6月随访,观察QRS波宽度,左心室收缩、舒张末内径,左心室射血分数.结果:心脏再同步治疗后患者QRS时限由术前的(160±32) ms减少到术后的(118±21 )ms,P＜0.05.术后的第3月和第6月,患者LVEDD由术前(74.5±14.1 )mm减少到(66.2±9.5)mm、(64.3±11.2) mm,P＜0.01;患者LVESD由术前(65.2±10.2)mm减少到(57.3±9.2)mm、(56.2±10.9)mm,P＜0.01;LVEF由术前的(0.24±0.09)增加到(0.36±0.11)、(0.38±0.14),P＜0.01.结论:心脏再同步化治疗是慢性心力衰竭治疗的有效方法.