CONTRIBUTION OF EXERCISING LEGS TO THE SLOW COMPONENT OF OXYGEN-UPTAKE KINETICS IN HUMANS

被引:372
作者
POOLE, DC
SCHAFFARTZIK, W
KNIGHT, DR
DERION, T
KENNEDY, B
GUY, HJ
PREDILETTO, R
WAGNER, PD
机构
关键词
LEG BLOOD FLOW; OXYGEN EXTRACTION; FATIGUE; POTASSIUM; WORK EFFICIENCY;
D O I
10.1152/jappl.1991.71.4.1245
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
Rates of performing work that engender a sustained lactic acidosis evidence a slow component of pulmonary O2 uptake (VO2) kinetics. This slow component delays or obviates the attainment of a stable VO2 and elevates VO2 above that predicted from considerations of work rate. The mechanistic basis for this slow component is obscure. Competing hypotheses depend on its origin within either the exercising limbs or the rest of the body. To resolve this question, six healthy males performed light nonfatiguing [approximately 50% maximal O2 uptake (VO2max)] and severe fatiguing cycle ergometry, and simultaneous measurements were made of pulmonary VO2 and leg blood flow by thermodilution. Blood was sampled 1) from the femoral vein for O2 and CO2 pressures and O2 content, lactate, pH, epinephrine, norepinephrine, and potassium concentrations, and temperature and 2) from the radial artery for O2 and CO2 pressures, O2 content, lactate concentration, and pH. Two-leg VO2 was thus calculated as the product of 2 x blood flow and arteriovenous O2 difference. Blood pressure was measured in the radial artery and femoral vein. During light exercise, both pulmonary and leg VO2 remained stable from minute 3 to the end of exercise (26 min). In contrast, during severe exercise [295 +/- 10 (SE) W], pulmonary VO2 increased 19.8 +/- 2.4% (P < 0.05) from minute 3 to fatigue (occurring on average at 20.8 min). Over the same period, leg VO2 increased by 24.2 +/- 5.2% (P < 0.05). Increases of leg and pulmonary VO2 were highly correlated (r = 0.911), and augmented leg VO2 could account for 86% of the rise in pulmonary VO2. Leg blood flow increased from 17.1 +/- 1.8 to 19.7 +/- 2.6 l/min (P < 0.05) in association with decreased limb vascular resistance (14.5 +/- 1.5 mmHg.l-1.min at minute 3, 12.9 +/- 2.1 mmHg.l-1.min at fatigue). At each time point analyzed, the contribution of increased blood flow and increased O2 extraction to the rise of leg VO2 was not different. We conclude that the slow component of VO2 kinetics at severe exercise reflects predominantly increased leg VO2, which precludes a dominant role for factors such as ventilatory, cardiac, or auxiliary muscle work and metabolic stimulation at sites outside the exercising limbs.
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页码:1245 / 1253
页数:9
相关论文
共 35 条
[1]   RELATIONSHIP BETWEEN EXCESS RESPIRATORY METABOLISM AND UTILIZATION OF INTRAVENOUSLY INFUSED SODIUM RACEMIC LACTATE AND SODIUM-L (-) LACTATE [J].
ALPERT, NR ;
ROOT, WS .
AMERICAN JOURNAL OF PHYSIOLOGY, 1954, 177 (03) :455-462
[2]   MAXIMAL PERFUSION OF SKELETAL-MUSCLE IN MAN [J].
ANDERSEN, P ;
SALTIN, B .
JOURNAL OF PHYSIOLOGY-LONDON, 1985, 366 (SEP) :233-249
[3]   DYNAMIC KNEE EXTENSION AS MODEL FOR STUDY OF ISOLATED EXERCISING MUSCLE IN HUMANS [J].
ANDERSEN, P ;
ADAMS, RP ;
SJOGAARD, G ;
THORBOE, A ;
SALTIN, B .
JOURNAL OF APPLIED PHYSIOLOGY, 1985, 59 (05) :1647-1653
[4]  
ASTRAND PO, 1961, J APPL PHYSIOL, V16, P977
[5]   ANAEROBIC ENERGY-PRODUCTION AND O-2 DEFICIT-DEBT RELATIONSHIP DURING EXHAUSTIVE EXERCISE IN HUMANS [J].
BANGSBO, J ;
GOLLNICK, PD ;
GRAHAM, TE ;
JUEL, C ;
KIENS, B ;
MIZUNO, M ;
SALTIN, B .
JOURNAL OF PHYSIOLOGY-LONDON, 1990, 422 :539-559
[6]   DEPRESSING EFFECTS OF CALCIUM-ANTAGONISTS ON OXYGEN-CONSUMPTION IN ISOLATED SKELETAL-MUSCLE DURING POTASSIUM DEPOLARIZATION [J].
BARNES, WS .
CANADIAN JOURNAL OF PHYSIOLOGY AND PHARMACOLOGY, 1988, 66 (06) :836-840
[7]   EFFECT OF ENDURANCE TRAINING ON POSSIBLE DETERMINANTS OF VO2 DURING HEAVY EXERCISE [J].
CASABURI, R ;
STORER, TW ;
BENDOV, I ;
WASSERMAN, K .
JOURNAL OF APPLIED PHYSIOLOGY, 1987, 62 (01) :199-207
[8]   THE INHIBITION OF RABBIT SKELETAL-MUSCLE CONTRACTION BY HYDROGEN-IONS AND PHOSPHATE [J].
COOKE, R ;
FRANKS, K ;
LUCIANI, GB ;
PATE, E .
JOURNAL OF PHYSIOLOGY-LONDON, 1988, 395 :77-97
[9]  
COURNAND A, 1954, T ASSOC AM PHYSICIAN, V67, P162
[10]   CHEMICAL ENERGETICS OF SLOW-TWITCH AND FAST-TWITCH MUSCLES OF THE MOUSE [J].
CROW, MT ;
KUSHMERICK, MJ .
JOURNAL OF GENERAL PHYSIOLOGY, 1982, 79 (01) :147-166