田径运动员最大摄氧量和无氧功测试中血乳酸的应用

目的：研究田径运动员最大摄氧量和wingate测试后血乳酸的变化，分析血乳酸对测试结果的意义。方法：测试田径短跑运动员36例和中长跑运动员29例的最大摄氧量和wingate无氧功，以及测试后的血乳酸值。结果：最大摄氧量测试后血乳酸数值为9—11mmol／L左右，摄氧量与乳酸值没有直接相关关系，但不同项目之间有一定的差异；wingate测试后血乳酸数值一般大于12mmol／L，测试的主要评价指标与乳酸值都有较高的相关关系。结论：血乳酸值对于最大摄氧量测试意义不大，但对于Wingate测试可以作为一项辅助评价指标。     

7圈滑行成绩并血乳酸值对运动训练及运动员功能状态的监控作用

目的通过少儿短道速滑运动员7圈滑行成绩与血乳酸值来评定竞技水平,对提高运动员运动训练水平有着重要实践价值。方法由教练员指挥控制的7圈滑行,强度要求本人最大摄氧量100%～120%,滑行结束后3～5min取末稍血测定乳酸值,同时记录成绩。结果7圈滑行后血乳酸可达到,男6.3～9.6mmol/L,女:5.8～11mmol/L;成绩分别为男73.40～80.31s,女:74.93～80.79s。结论7圈滑行是评定短道速滑运动员竞技水平可靠手段,配合血乳酸的测试,对更客观评定运动员竞技水平及功能状态起到科学互补作用。     

7圈滑行成绩并血乳酸值对运动训练及运动员功能状态的监控作用

目的通过少儿短道速滑运动员7圈滑行成绩与血乳酸值来评定竞技水平，对提高运动员运动训练水平有着重要实践价值。方法由教练员指挥控制的7圈滑行，强度要求本人最大摄氧量100％～120％，滑行结束后3～5min取末稍血测定乳酸值，同时记录成绩。结果7圈滑行后血乳酸可达到，男6．3～9．6mmol／L，女：5．8～11mmol／L；成绩分别为男73．40～80．31s，女：74．93～80．79s。结论7圈滑行是评定短道速滑运动员竞技水平可靠手段，配合血乳酸的测试，对更客观评定运动员竞技水平及功能状态起到科学互补作用。     

正常新生儿及胎儿宫内窘迫新生儿乳酸测定的意义

目的 探讨正常新生儿乳酸的范围及脐动脉血乳酸水平与脐血血气的相关关系.方法 对108例正常新生儿及55例诊断胎儿宫内窘迫的新生儿,在建立自主呼吸以前,分别采集脐动脉血、脐静脉血及末梢血,测定相应的乳酸值,并对临床诊断胎儿官内窘迫的新生儿同时监测脐动脉血的血气分析.结果 无临床胎儿官内窘迫组新生儿脐动脉血平均乳酸值为(2.6±1.4) mmol/L,脐静脉血平均乳酸值为(2.3±1.2)mmol/L,末梢血的平均乳酸值为(2.8±1.3)mmol/L.脐动脉血与脐静脉血、末梢血的乳酸水平呈明显的直线相关;胎儿宫内窘迫组新生儿脐动脉血平均乳酸值为(4.3±2.4)mmol/L,脐静脉血平均乳酸值为(3.9±2.1)mmol/L,末梢血的平均乳酸值为(4.1±2.0) mmol/L;正常新生儿与宫内窘迫新生儿两组间的乳酸值比较差异有统计学意义(P＜0.01).结论 新生儿脐动脉、脐静脉、末梢血的乳酸值具有明显的相关关系,乳酸检测可作为代谢性酸中毒的监测指标.     

优秀女子赛艇运动员比赛前后血乳酸、血尿素及血清肌酸激酶跟踪测试

目的:跟踪测试优秀女子赛艇运动员比赛前后血乳酸、血尿素及血清肌酸激酶的变化,探讨女子赛艇运动员机体能量物质代谢和赛后疲劳恢复的特点。方法:选取2005-07/09湖北省水上运动中心优秀女子运动员14名,其中国家健将级运动员7名,国家一级运动员7名;平均年龄(22±4)岁,训练年限(4.1±1.4)年,身高(174.2±3.1)cm,体质量(68.6±4.7)kg。14名运动员分别于2000m划艇比赛当日晨空腹、赛前15min、赛后5min,1h及24h抽取指尖血60μL,进行血乳酸、血尿素、血清肌酸激酶检测。结果:14名运动员全部进入结果分析。①比赛前后运动员血乳酸水平的变化:运动员空腹血乳酸水平为(1.22±0.45)mmol/L,赛前15min为(2.89±0.49)mmol/L。赛后5min血乳酸浓度高达(11.51±1.72)mmol/L,与空腹水平比较差异有显著性意义(t=3.077,P<0.01)。赛后24h血乳酸浓度显著下降至(1.76±0.24)mmol/L,与空腹水平基本接近(t=0.027,P>0.05)。②比赛前后运动员血尿素水平的变化:与空腹血尿素水平比较,运动员赛后5min血尿素浓度明显升高[(5.45±0.47),(6.13±1.00)mmol/L;t=2.416,P<0.05]。赛后24h血尿素浓度下降至(5.94±0.85)mmol/L,仍高于空腹水平(t=2.682,P<0.05)。③比赛前后运动员血清肌酸激酶活性的变化:与赛前比较,运动员赛后5min血清肌酸激酶活性明显升高[(3.38±1.58),(6.13±3.25)nkat/L;t=4.968,P<0.01]。赛后1h血清肌酸激酶活性开始下降,至赛后24h与赛前基本相似(t=1.537,P>0.05)。结论:①赛后5min血乳酸、血尿素、血清肌酸激酶活性显著高于赛前,赛后1h血乳酸消除迅速,但仍未恢复到正常水平。提示赛艇是一种以糖酵解系统为主、无氧 有氧代谢混合型供能的运动项目。②赛艇比赛使酸性产物生成增多,血乳酸、血尿素、血清肌酸激酶可作为运动强度和机能恢复的指标。③赛艇比赛后至少24h内,机体处于蛋白质降解增强状态,建议恢复期增加饮食糖和蛋白质摄入量,以促进合成代谢,加快功能恢复过程。     

世居高原运动员冬训期间一次性血液生化指标值测试

目的:分析世代在高原居住(世居高原)不同运动项目运动员训练后不同生化指标恢复值的适宜界限。方法:对2004-11/2005-03昆明冬训期间347名云南省省队运动员的身体功能状况进行跟踪测试,男202名,女145名,所有受试对象均知情同意。运动员经过1d的休息后,以次日晨的测试值定为恢复值。于周日休息后,周一清晨分别采取运动员指血及静脉血,离心提取血清。其中血红蛋白用上海722分光光度计和瑞士倍肯AC900 红细胞计数仪测定;红细胞计数、红细胞压积用瑞士倍肯AC900 红细胞计数仪测定;血清肌酸激酶和血尿素氮用德国半自动生化分析仪测定;血清睾酮用放射免疫分析法测定。结果:347名运动员全部进入结果分析,无脱落。世居高原运动员训练后不同生化指标恢复值:①全血血红蛋白男运动员不应低于155g/L,女运动员不应低于140g/L。②红细胞男运动员不应低于5.00×1012L-1,女运动员不应低于4.70×1012L-1;红细胞压积男运动员不应低于47.0%,女运动员不应低于44.0%。③血清肌酸激酶男运动员不应高于5001nkat/L,女运动员不应高于3334nkat/L。④尿素氮男运动员不应高于6.50mmol/L,女运动员不应高于6.00mmol/L。⑤血清睾酮男运动员不应低于21.7nmol/L,女运动员不应低于1.1nmol/L。结论:①世居高原运动员冬训期间各指标的具体恢复值界限可作为对各个运动员监测的参考依据。②男运动员各项指标的恢复值界限均高于女运动员,对于同一队的监测应该区别对待。     

补充低聚糖对人体大强度运动能力的影响

目的:探讨补充低聚糖对人体大强度运动能力的影响。方法:选择16名身体健康的体育学院男生作为实验对象,单纯随机分为实验组和对照组,每组8名,测定最大吸氧量,以80%最大摄氧量的运动强度蹬车至力竭,观察补充80g/L的低聚糖对运动员血糖、血乳酸、心率、运动时间及做功量的影响。结果:安静时两组血糖和血乳酸值无明显差异(P>0.05);运动中实验组血糖(mmol/L)高于对照组,随运动时间的延长组间差异显著(5.29±1.07～6.46±0.78和4.71±0.84～5.36±0.80,P均<0.05),运动后30min实验组血糖浓度显著高于对照组(6.32±2.17和5.24±1.95,P<0.05);血乳酸(mmol/L)的变化则实验组在运动中(6.69±1.57～7.39±1.19)及运动后(6.18±1.28～5.19±1.14)显著低于对照组(P<0.05);且实验组运动时间(47±12)min、做功量(174.9±3.6)kJ均显著超过对照组(P<0.05)。结论:大强度运动时补充低聚糖有利于持久维持受试者的血糖水平,降低血乳酸浓度,增加做功量和延长运动时间。     

篮球运动训练后恢复方法对血乳酸浓度恢复的影响

目的:分析激烈的篮球比赛后间歇期间的不同休息方式对消除血乳酸的影响。方法:于2004-02/06选择广东蓝球队男子运动员5名为研究对象,年龄(20±2)岁,身高(187.7±2.8)cm,体质量(80.5±4.4)kg,最大摄氧量(50.2±5.0)mL/(kg·min)。受试者在比赛间歇中的休息方式分安静和活动两种。第一场比赛的两次休息期间均吸正常空气、自然恢复。第二场比赛的两次休息期间吸体积分数为0.7的氧气和体积分数为0.3的氮气混合气,吸氧时间为3min。第一场和第二场比赛的间隔时间为2d。进行功率自行车递增负荷运动实验。采用2900型气体代谢分析仪测定最大摄氧量,采用ISY-1500型全血乳酸分析仪测定血乳酸浓度。采用心率测定仪测定运动中最大心率和恢复期间的心率。结果:纳入受试者5名,均进入结果分析。①在间歇期间吸正常空气的心率变化与吸高浓度氧的变化差异无显著性[安静方式休息分别为(119±3),(118±1)次/min;活动方式休息分别为(134±2),(131±4)次/min,P>0.05]。②在间歇期间吸正常空气时,活动方式休息的血乳酸浓度比安静方式休息明显减少[分别为(3.99±0.97),(4.35±0.45)mmol/L,P<0.05]。无论是安静或活动方式休息,在间歇期间吸高浓度氧后比吸氧前明显减少,差异显著[安静方式休息分别为(3.22±0.66),(4.59±0.96)mmol/L,活动方式休息分别为(2.92±0.81),(4.95±1.53)mmol/L,P<0.05]。结论:活动方式休息与吸高浓度氧相结合可使血乳酸浓度显著减少。     

摔跤运动员不同季节赛前训练与血生化指标的变化特征

目的:探讨男子摔跤运动员不同季节训练对其生化指标的影响。方法:以摔跤队9名运动员为研究对象,分别在安静、大运动量、大运动强度后及恢复时取血或尿样,用血乳酸分析仪、分光光度计、尿液分析仪、放射免疫法测试血乳酸、血尿素氮、血红蛋白、尿蛋白、血睾酮和血清铁蛋白。结果:血乳酸(mmol/L):冬训时大强度安静值(1.24±0.52)大于夏训时(0.47±0.30);冬训时最高值(5.50±2.31)小于夏训时(8.30±1.45)。血睾酮(μg/L):冬训时(5.90±1.48)小于夏训时(7.41±2.04)。铁蛋白(μg/L):冬训时(1.33±0.61)高于夏训时(0.39±0.32)。血红蛋白(g/L):冬训时(155±8);夏训时(148±6)。结论:摔跤运动员各项指标水平与季节有关,应在有氧能力基础上应加强无氧糖酵解训练,提高无氧代谢能力。     

血浆乳酸测定在蓝球运动员训练中的应用

目的 通过测定血浆中乳酸浓度对蓝球运动员的训练进行指导评价,提高训练成绩.方法 用全自动生化分析仪分别测定蓝球运动员的训练前、中、后及健康人群中乳酸浓度.结果 健康人群中血浆中的乳酸含量为1.02±0.57 mmol/L,蓝球运动员训练前、中、后血浆中的乳酸含量为1.12±0.48,6.26±0.61及2.39±0.49 mmol/L.结论 血浆乳酸是反映运动能力的一种生化指标,该项目对蓝球运动员训练具有指导和评价作用,也是现代运动训练科学化的指标之一.血浆乳酸测定可以为教练员安排训练强度提供客观依据.     

优秀女子短跑运动员有氧-无氧能力特征及训练效应

目的:通过女子短跑运动员1年训练中有氧-无氧能力的跟踪观察,为训练监控中的综合分析评定提供参考。方法:21名优秀女子短跑(100～400m)运动员和10名中跑(800～1500m)运动员参加预期性研究;分别在Max-1气体代谢分析仪上完成最大有氧能力试验;在Monark834E功率车上完成改进的Wingate无氧试验。根据年训练周期,共进行3次该组合试验并分析其间的关系。结果:在基本能力评定中,短跑组VO2max显著低于中跑组(平均为2.41和2.74L/min,P<0.05);最大无氧功(PeakPower,P-peak)和平均无氧功(AveragePower,P-ave)显著高于中跑组(分别为744.2和584.2W,P<0.01;517.7和427.8W,P<0.01)。在跟踪测试中,短跑组显示前半周期最大输出功率(MaximalOutputPower,Wmax)、最大通气量(MaximalVoluntaryVentilation,VEmax)和P-ave显著提高,后半周期VO2max,VEmax和最小无氧功(LowPower,P-low)明显下降,而起始无氧功(StartofLoading,P-sta)和P-peak显著提高。中跑组仅在后半周期VO2max显著提高;VO2max,Wmax和VEmax分别与P-low,P-ave呈正相关(r=0.47～0.70,P<0.05)。结论:速度耐力是短跑的关键素质,不仅与无氧代谢能力有直接关系,也离不开有氧供能基础.短跑成绩的提高,需重视最大速度和专项耐力的协调发展。对有氧-无氧能力的组合监测,有     

Growth hormone secretion in acid-base alterations at rest and during exercise.

1. Seven healthy males were studied during cycle ergometer exercise at 33%, 66% and 90% of VO2 max. on three occasions when NH4C1, NaHCO3 or CaCO3 (as a control substance) were administered in gelatin capsules double blind and in randomized order. Plasma growth hormone (HGH), lactic acid and hydrogen ion concentration ([H+]) were measured at frequent intervals. 2. Ammonium chloride produced highest blood [H+] and NaHCO3 the lowest. These differences were maintained during exercise and in recovery. Plasma lactic acid concentrations were similar at rest. At 66%, 90% VO2 max. and recovery lactic acid was highest with NaHCO3 and lowest with NH4C1. 3. Exercise stimulated HGH secretion in all studies and the elevation was proportional to the intensity of the exercise. NH4C1 caused a variable elevation of HGH at rest and 33% VO2 max. At 66% VO2 max., plasma HGH was significantly elevated to similar concentrations in all studies and, at 90% VO2 max., HGH was highest with NaHCO3. 4. An infusion of sodium L(+)-lactate producing plasma lactate concentrations of 3-5 mmol/l did not influence HGH secretion. 5. Exercise is a physiological stimulus to HGH secretion and the mechanism is independent of blood [H+] and lactate concentrations.     

Study of blood flow parameters measured in femoral artery after exercise: correlation with maximum oxygen uptake

To study the recovery periods of blood flow parameters in muscles after anaerobic exercise, instantaneous and mean blood flow velocity curves were recorded in the femoral artery in 22 sportsmen at rest and during the first 4 min of recovery after exercise (Ruffier-Dickson test). A flat ultrasonic probe connected to a Doppler system (Flow-Tester) was fixed on the skin at the level of the common femoral artery. From Doppler recordings, we calculated periods of recovery (return to baseline) of femoral blood flow velocity (FBFV RP), heart rate (HR RP) and femoral stroke distance (FSD RP). Also, Ruffier-Dickson index (RDI), VO(2)max in mL/kg(-1)/min(-1) and number of training hours were determined. We observed a high correlation between FBFV RP and VO(2)max (p = 0. 0002), and significant correlation between FSD RP and VO(2)max (p = 0.0238) and RDI (p = 0.0451). In conclusion, there is a excellent correlation between blood flow velocity recovery period in femoral artery after moderate exercise and VO(2)max in high-level sportsmen. The method of testing is simple and based on conventional Doppler technique. It can be used for the follow-up of training levels in sportsmen.     

心肺功能运动试验和静态肺功能对评判COPD患者病情轻重程度的比较

【目的】比较心肺功能运动试验（CPET）和静态肺功能（PFT）对评判慢性阻塞性肺疾病（COPD）患者病情轻重的相关性。【方法】98名处于稳定期的COPD患者分别进行PFT和CPET检查;以PFT中FEV,％（占预计值％）和CPET中最大公斤摄氧量（VO2max／kg）两种不同方法判断COPD患者病情轻重并作相关性分析,同时以VO2max／kg判断COPD病情重于以FEV1％判断的患者与余下的患者作比较。【结果】两者方法判断COPD患者病情轻重无相关关系;以VO2max／kg判断病情较重的患者其年龄、FEV1％、V02max／kg、无氧阈占最大摄氧量比值（AT／VO2max）、最大呼吸储备（BRmax）与其他患者比较差异均有显著性。【结论】①CPET和PFT判断COPD患者病情并无相关性,但CPET反映病情更全面。②CPET有助于发现COPD患者潜在的心功能问题。     

Effects of graduated compression stockings on blood lactate following an exhaustive bout of exercise

To determine the effects of wearing graduated compression stockings (GCS) on the exercise response, twelve high fit males served as subjects in a series of two experiments. The first experiment consisted of six subjects performing two tests of maximal oxygen consumption (VO2 max) on a treadmill with and without GCS. The second experiment consisted of six subjects performing three separate three minute tests on a bicycle ergometer at 110% of their VO2 max. The experimental conditions for the three tests were: GCS worn during the test and recovery (GCS), GCS worn only during the test (GCS-O/O) and no stockings worn during either the test or recovery (NO-GCS). Oxygen consumption (VO2) was measured at rest, throughout the duration of all tests and during recovery in both experiments. Blood samples were obtained at rest and at 5, 15, 30, 45 and 60 minutes post exercise in the first experiment and at rest and at 5, 15 and 30 minutes post exercise in the second experiment for the determination of lactate and hematocrit. The use of GCS in the first experiment resulted in no significant difference in VO2 max, recovery VO2 or plasma volume shifts. Lactate values were lower throughout the duration of the recovery period with the 15 minute values being significantly different with the use of GCS. Significant differences in post exercise blood lactate values were found in the second experiment. The GCS trial resulted in significantly less lactate when compared to the GCS-O/O and the NO-GCS trials. There was no significant difference in post exercise lactate values between the NO-GCS and the GCS-O/O trials. Plasma volume changes were not significantly different among trials. Results of both experiments showed recovery lactate values to be lower with the use of GCS. These lower values are not ascribable to plasma volume shifts but rather appear to be due to an inverse gradient created by the GCS resulting in the lactate being retained in the muscular bed.     

Blood metabolite data in response to maximal exercise in healthy subjects

Maximal exercise test with gas exchange measurement evaluates exercise capacities with maximal oxygen uptake (VO(2) max) measurement. Measurements of lactate (L), lactate/pyruvate ratio (L/P) and ammonium (A) during rest, exercise and recovery enhance interpretative power of maximal exercise by incorporating muscular metabolism exploration. Maximal exercise test with gas exchange measurement is standardized in cardiopulmonary evaluations but, no reference data of blood muscular metabolites are available to evaluate the muscular metabolism. We determined normal values of L, L/P and A during a standardized maximal exercise and recovery in 48 healthy sedentary volunteers and compared with results obtained in four patients with exercise intolerance and a mitochondrial disease. In healthy subjects, L, L/P and A rose during exercise. In 98% of them L, L/P or A decreased between the fifth and the fifteenth minutes of recovery. In mitochondrial patients, VO(2) max was normal or low, and L, L/P and A had the same evolution as normal subjects or showed no decrease during recovery. We gave normal L, L/P and A values, which establish references for a maximal exercise test with muscular metabolism exploration. This test is helpful for clinicians in functional evaluation, management and treatment of metabolic myopathy and would be a useful tool in diagnosis of metabolic myopathy.     

Mechanism of enhanced insulin sensitivity in athletes. Increased blood flow, muscle glucose transport protein (GLUT-4) concentration, and glycogen synthase activity.

We examined the mechanisms of enhanced insulin sensitivity in 9 male healthy athletes (age, 25 +/- 1 yr; maximal aerobic power [VO2max], 57.6 +/- 1.0 ml/kg per min) as compared with 10 sedentary control subjects (age, 28 +/- 2 yr; VO2max, 44.1 +/- 2.3 ml/kg per min). In the athletes, whole body glucose disposal (240-min insulin clamp) was 32% (P < 0.01) and nonoxidative glucose disposal (indirect calorimetry) was 62% higher (P < 0.01) than in the controls. Muscle glycogen content increased by 39% in the athletes (P < 0.05) but did not change in the controls during insulin clamp. VO2max correlated with whole body (r = 0.60, P < 0.01) and nonoxidative glucose disposal (r = 0.64, P < 0.001). In the athletes forearm blood flow was 64% greater (P < 0.05) than in the controls, whereas their muscle capillary density was normal. Basal blood flow was related to VO2max (r = 0.63, P < 0.05) and glucose disposal during insulin infusion (r = 0.65, P < 0.05). The forearm glucose uptake in the athletes was increased by 3.3-fold (P < 0.01) in the basal state and by 73% (P < 0.05) during insulin infusion. Muscle glucose transport protein (GLUT-4) concentration was 93% greater in the athletes than controls (P < 0.01) and it was related to VO2max (r = 0.61, P < 0.01) and to whole body glucose disposal (r = 0.60, P < 0.01). Muscle glycogen synthase activity was 33% greater in the athletes than in the controls (P < 0.05), and the basal glycogen synthase fractional activity was closely related to blood flow (r = 0.88, P < 0.001). In conclusion: (a) athletes are characterized by enhanced muscle blood flow and glucose uptake. (b) The cellular mechanisms of glucose uptake are increased GLUT-4 protein content, glycogen synthase activity, and glucose storage as glycogen. (c) A close correlation between glycogen synthase fractional activity and blood flow suggests that they are causally related in promoting glucose disposal.     

递增负荷运动下血乳酸丙酮酸的动态变化规律及乳酸阈机制探讨

背景:作者曾提出:“运动中有氧产能过程与当时耗能过程不匹配是代谢发生转变的原因;而丙酮酸转化成乳酸的直接作用是防止丙酮酸在胞浆内堆积,防止其堆积对糖酵解产能过程的抑制,以保证酵解过程的快速供能;这一步生化反应的机制是对畅通糖代谢酵解途径供能速率的调节”的假说。目的:观察补充吸氧对代谢转变有无影响,分别从人体和动物水平上探讨乳酸阈强度(代谢转变时)下代谢转变的机制,验证人体和动物结果的一致性。设计:随机对照观察。单位:河北师范大学体育学院,廊坊师范学院体育系。对象:受试者为24名体育专业本科男生,体质量为(58±4)kg,身高为(175±6)cm,年龄(21±2)岁,二级运动员12人,无等级学生12人;雄性SD大鼠30只。方法:整体实验于2006-04/06河北师范大学体育学院运动生理机能实验室完成。24名学生分为二级运动员组和无等级训练组,各12名,进行递增负荷功率自行车运动;选取30只SD大鼠随机分为负重游泳训练组15只,无负重游泳适应组15只,负重游泳训练组进行递增负荷游泳运动。首先确定人体组与大鼠组各自的代谢转变强度,后在正常吸空气与补充吸氧条件下重复其前一阶段运动。分别在重复运动前及递增负荷运动到乳酸阈强度下,测定人体及大鼠的静脉血氧分压、丙酮酸、乳酸含量。人体组每2min递增负荷50W,大鼠组每2min递增负荷是体质量的1%,直至不能坚持为止。选择递增负荷运动方法,让体内代谢逐步由有氧向无氧代谢过度,确定过度点即乳酸阈强度。通过静脉血氧分压、丙酮酸、乳酸含量的前后对比和补充与否对各指标有无影响,以及人体和动物的结果是否一致,以证明假说的信度和效度。主要观察指标:人体组和大鼠组乳酸阈强度下及补充吸氧前后的静脉血氧分压、丙酮酸、乳酸含量。结果:受试者24名和30只大鼠全部进入结果分析。①人体受试者(两组)和30只大鼠(两组)在递增负荷运动中每级负荷2min末取血所得到的乳酸曲线,明显反映出了血乳酸拐点所对应的代谢转变强度及训练水平的差异,有训练者的血乳酸拐点明显置后。②在乳酸阈强度下,不论是否吸氧,人体组和大鼠组的血乳酸含量与氧分压之间均不相关[(3.61±0.56),(5.43±0.55)mmol/L;(4.46±0.86),(7.80±0.27)kPa,r=0.31,0.31,P>0.05],整个测试过程人体组血氧饱和度均不低于98%;而两组受试血乳酸与血丙酮酸含量之间差异均有非常显著性意义[丙酮酸:(1.04±0.16),(0.91±0.37)mmol/L,P<0.001]。③人体组和大鼠组在重复运动前及乳酸阈强度下,丙酮酸平均值分别是(0.97±0.17),(1.04±0.16)mmol/L;(0.93±0.25),(0.91±0.37)mmol/L。两组受试重复运动前与乳酸阈强度时的血丙酮酸含量差异均无显著性意义(P>0.05)。结论:运动中由有氧向无氧代谢转变时体内不缺氧,补充吸氧对代谢的转变没有影响;丙酮酸不易通过肌细胞膜而乳酸可以通过。实验结果支持丙酮酸转化成乳酸的直接作用是防止丙酮酸在胞浆内堆积的观点。     

Evidence for a significant myocardial contribution to total metabolic burden during hypothermic cardiopulmonary bypass: a study of continuously measured oxygen consumption and arterial lactate levels in pigs

OBJECTIVE: We assessed the causes of imbalance of oxygen transport by continuously measuring oxygen consumption (VO2) during hypothermic cardiopulmonary bypass (CPB) in pigs. METHODS: Six pigs (17.2+/-1.6 kg) underwent hypothermic (32 degrees C) CPB for 180 min with 120 min of aortic crossclamping (ACC). An AMIS 2000 mass spectrometer was adapted for the on-line measurement of VO2. Arterial lactate was measured at the beginning of CPB, the end of hypothermia, before and 10 min after ACC release, 20 min later, and at the end of CPB. RESULTS: Arterial lactate increased from 1.8+/-0.7 to 5.1+/-1.8 mmol/L during CPB. Hypothermia reduced VO2 by 0.63+/-0.29 mlmin/kg per degrees C, but lactate increased to 4.2+/-1.5 mmol/L (p <0.05). The most rapid rise of VO2 and lactate occurred during the first 10 min after ACC removal, accounting for 26% and 68%, respectively, of the total rise during rewarming. CONCLUSIONS: Inadequate tissue oxygenation persists throughout hypothermic CPB. The rise in systemic VO2 and lactate immediately after ACC release may reflect inadequate oxygen transport within the myocardium during ischemia and manifest on reperfusion. This simple technique may be used to provide important information regarding the dynamic balance of systemic and myocardial oxygen transport during ischemia-reperfusion.     

Detection of lactate threshold by including haemodynamic and oxygen extraction data

To date, few attempts have been made to correlate cardiovascular variables to lactate threshold (L(T)). This study was designed to determine the relationship between the accumulation of blood lactate and several haemodynamic variables during exercise. Eight male volunteer cyclists performed an incremental test on an electromagnetically braked cycle-ergometer consisting of a 50 W linear increase in workload every 3 min up to exhaustion. Blood lactate was measured with a portable analyser during each exercise step. Oxygen consumption (VO(2)) and pulmonary ventilation were measured by means of a mass spectrometer while heart rate, stroke volume and cardiac output (CO) were assessed by impedance cardiography. The arterio-venous oxygen difference (A-V O(2) Diff) was obtained by dividing VO(2) by CO. By applying the D(max) mathematical method, L(T) and thresholds of ventilatory and haemodynamic parameters were calculated. The Bland and Altman statistics used to assess agreement between two methods of measurement were applied in order to evaluate the agreement between L(T) and thresholds derived from ventilatory and haemodynamic data. The main result was that most of the haemodynamic variables did not provide thresholds which could be used interchangeably with L(T). Only the threshold of A-V O(2) Diff showed mean values that were no different compared to L(T) together with limits of agreement that were not very wide between thresholds (below +/-25%). Hence of the haemodynamic parameters, A-V O(2) Diff appears to be the one most closely coupled with lactate accumulation and consequently it is also the most suitable for non-invasive calculation of the L(T).