Reduced Oxygen Uptake During Steady State Exercise After 21-Day Mountain Climbing Expedition to 6,194 m

2001 ◽  
Vol 26 (2) ◽  
pp. 143-156 ◽  
Author(s):  
Maureen J. Macdonald ◽  
Howard J. Green ◽  
Heather L. Naylor ◽  
Christian Otto ◽  
Richard L. Hughson
Keyword(s):  
Blood Flow ◽  
Steady State ◽  
Oxygen Uptake ◽  
Respiratory Exchange Ratio ◽  
Submaximal Exercise ◽  
Metabolic Efficiency ◽  
Mountain Climbing ◽  
Leg Blood Flow ◽  
Exercise Onset ◽  
State Formula

We investigated the effect of a 21-day climbing expedition to 6,194 m on the oxygen uptake [Formula: see text] and leg blood flow (LBF) responses to submaximal exercise in five healthy, fit men during two-leg kicking exercise at 0-W and 50-W. Tests were completed 1 week before and 3 days after altitude acclimatization. The adaptation of [Formula: see text] at exercise onset was described by the time to 63% of the new steady state. Steady state [Formula: see text] during 50-W exercise was less post-climb (1290 ± 29 mL/min, mean ± SE) than pre-climb (1413 + 63 mL/min, P < .05). [Formula: see text] adapted more slowly at the onset of 50-W exercise post-climb. There were no differences in the steady state LBF during 50-W exercise, the increase above baseline, or the adaptation post-climb. Respiratory exchange ratio was greater at 50-W post-climb compared to pre-climb. Reduced steady state [Formula: see text] during exercise after exposure to high altitude is consistent with an increase in metabolic efficiency. Key words: work efficiency, leg blood flow, altitude, hypoxia, Doppler ultrasound

Oxygen transport during steady-state submaximal exercise in chronic hypoxia

1991 ◽  
Vol 70 (3) ◽  
pp. 1129-1136 ◽  
Author(s):  
E. E. Wolfel ◽  
B. M. Groves ◽  
G. A. Brooks ◽  
G. E. Butterfield ◽  
R. S. Mazzeo ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Steady State ◽  
Sea Level ◽  
Vascular Resistance ◽  
Barometric Pressure ◽  
Submaximal Exercise ◽  
Leg Blood Flow ◽  
Total Body ◽  
O2 Delivery

Arterial O2 delivery during short-term submaximal exercise falls on arrival at high altitude but thereafter remains constant. As arterial O2 content increases with acclimatization, blood flow falls. We evaluated several factors that could influence O2 delivery during more prolonged submaximal exercise after acclimatization at 4,300 m. Seven men (23 +/- 2 yr) performed 45 min of steady-state submaximal exercise at sea level (barometric pressure 751 Torr), on acute ascent to 4,300 m (barometric pressure 463 Torr), and after 21 days of residence at altitude. The O2 uptake (VO2) was constant during exercise, 51 +/- 1% of maximal VO2 at sea level, and 65 +/- 2% VO2 at 4,300 m. After acclimatization, exercise cardiac output decreased 25 +/- 3% compared with arrival and leg blood flow decreased 18 +/- 3% (P less than 0.05), with no change in the percentage of cardiac output to the leg. Hemoglobin concentration and arterial O2 saturation increased, but total body and leg O2 delivery remained unchanged. After acclimatization, a reduction in plasma volume was offset by an increase in erythrocyte volume, and total blood volume did not change. Mean systemic arterial pressure, systemic vascular resistance, and leg vascular resistance were all greater after acclimatization (P less than 0.05). Mean plasma norepinephrine levels also increased during exercise in a parallel fashion with increased vascular resistance. Thus we conclude that both total body and leg O2 delivery decrease after arrival at 4,300 m and remain unchanged with acclimatization as a result of a parallel fall in both cardiac output and leg blood flow and an increase in arterial O2 content.(ABSTRACT TRUNCATED AT 250 WORDS)

Metabolic and hemodynamic responses of lower limb during exercise in patients with COPD

1998 ◽  
Vol 84 (5) ◽  
pp. 1573-1580 ◽  
Author(s):  
François Maltais ◽  
Jean Jobin ◽  
Martin J. Sullivan ◽  
Sarah Bernard ◽  
François Whittom ◽  
...  
Keyword(s):  
Blood Flow ◽  
Lactic Acidosis ◽  
Blood Lactate ◽  
Lower Limb ◽  
Submaximal Exercise ◽  
Exercise Intolerance ◽  
Early Exercise ◽  
Lactate Release ◽  
Leg Blood Flow ◽  
Copd Patients

Premature lactic acidosis during exercise in patients with chronic obstructive pulmonary disease (COPD) may play a role in exercise intolerance. In this study, we evaluated whether the early exercise-induced lactic acidosis in these individuals can be explained by changes in peripheral O2 delivery (D˙o 2). Measurements of leg blood flow by thermodilution and of arterial and femoral venous blood gases, pH, and lactate were obtained during a standard incremental exercise test to capacity in eight patients with severe COPD and in eight age-matched controls. No significant difference was found between the two groups in leg blood flow at rest or during exercise at the same power outputs. Blood lactate concentrations and lactate release from the lower limb were greater in COPD patients at all submaximal exercise levels (all P < 0.05). LegD˙o 2at a given power output was not significantly different between the two groups, and no significant correlation was found between this parameter and blood lactate concentrations. COPD patients had lower arterial and venous pH at submaximal exercise, and there was a significant positive correlation between venous pH at 40 W and the peak O2 uptake ( r = 0.91, P < 0.0001). The correlation between venous pH and peak O2 uptake suggests that early muscle acidosis may be involved in early exercise termination in COPD patients. The early lactate release from the lower limb during exercise could not be accounted for by changes in peripheralD˙o 2. The present results point to skeletal muscle dysfunction as being responsible for the early onset of lactic acidosis in COPD.

Exercise training enhances leg vasodilatory capacity of 65-yr-old men and women

1990 ◽  
Vol 69 (5) ◽  
pp. 1804-1809 ◽  
Author(s):  
W. H. Martin ◽  
W. M. Kohrt ◽  
M. T. Malley ◽  
E. Korte ◽  
S. Stoltz
Keyword(s):  
Blood Flow ◽  
Body Weight ◽  
Exercise Training ◽  
Oxygen Uptake ◽  
Endurance Exercise ◽  
Maximal Oxygen Uptake ◽  
Statistical Significance ◽  
Tissue Loss ◽  
Leg Blood Flow ◽  
Endurance Exercise Training

To determine whether extremity vasodilatory capacity may be augmented in older persons by endurance exercise training, lower leg blood flow and conductance were characterized plethysmographically at rest and during maximal hyperemia in 9 men and 10 women aged 64 +/- 3 (SD) yr before and after 31 +/- 6 wk of walking and jogging at 70-90% of maximal oxygen uptake for 45 min 3-5 days/wk. Maximal oxygen uptake expressed as milliliters per kilogram per minute improved 25% in men and 21% in women (P less than 0.01). Maximal leg blood flow and conductance increased in all nine men by an average of 39 +/- 33 (P less than 0.001) and 42 +/- 44% (P less than 0.004), respectively. Results were more variable in women and achieved unequivocal statistical significance only for maximal blood flow (+33 +/- 54% for blood flow and +29 +/- 55% for conductance; P less than 0.02 and P = 0.05, respectively). Body weight and skinfold adiposity declined in both sexes (P less than 0.05). Enhancement of vasodilatory capacity was related to weight loss in men and adipose tissue loss in women (r = 0.61 and 0.51, respectively; P less than 0.05). There were no significant changes in exercise capacity, body weight, or maximal blood flow in four male and three female controls aged 66 +/- 4 yr. Thus adaptability of the lower limb circulation to endurance exercise training is retained to at least age 65 yr.

Oxygen Uptake And Leg Blood Flow Kinetics And The Influence Of Exercise Training In Older Women

2007 ◽  
Vol 39 (Supplement) ◽  
pp. S359
Author(s):  
Liza Stathokostas ◽  
John M. Kowalchuk ◽  
Donald H. Paterson
Keyword(s):  
Blood Flow ◽  
Exercise Training ◽  
Oxygen Uptake ◽  
Older Women ◽  
Leg Blood Flow

Leg Blood Flow and Muscle Metabolism in Occlusive Arterial Disease of the Leg before and after Reconstructive Surgery

1975 ◽  
Vol 49 (3) ◽  
pp. 265-275 ◽  
Author(s):  
B. Pernow ◽  
B. Saltin ◽  
J. Wahren ◽  
R. Cronestrand ◽  
S. Ekeström
Keyword(s):  
Blood Flow ◽  
Oxygen Uptake ◽  
Reconstructive Surgery ◽  
Lactate Concentration ◽  
Creatine Phosphate ◽  
Arterial Disease ◽  
Thigh Muscle ◽  
Work Intensity ◽  
Leg Blood Flow ◽  
Occlusive Arterial Disease

1. Leg blood flow, uptake of oxygen and glucose and release of lactate by the leg and changes in intramuscular concentrations of metabolites were studied at rest and during exercise of increasing work loads in thirteen patients with occlusive disease of the iliac or superficial femoral arteries. 2. Leg blood flow (dye-dilution technique) and oxygen uptake during exercise were low and levelled with increasing work load. Considerable increases were noted in muscle lactate concentration and in the net release of lactate from the exercising leg. Muscle content (needle-biopsy technique) of ATP and creatine phosphate decreased during exercise, with an almost complete depletion of creatine phosphate in three patients. The decrease in muscle glycogen during work did not differ significantly from that of control subjects. 3. Repeated exercise after reconstructive surgery showed a considerable improvement in physical working capacity. Leg blood flow and oxygen uptake during exercise were significantly higher than before surgery and increased linearly in relation to work intensity. The decrease in creatine phosphate and lactate concentration of the thigh muscle during exercise was less pronounced and the release of lactate was lower than before vascular reconstruction. 4. It is suggested that the onset of the severe muscle symptoms during exercise in patients with occlusive arterial disease of the leg may be related to a low concentration of ATP and creatine phosphate in the affected muscles.

Reduced Leg Blood Flow during Submaximal Exercise in Type 2 Diabetes

2008 ◽  
Vol 40 (4) ◽  
pp. 612-617 ◽  
Author(s):  
SOPHIE LALANDE ◽  
SILMARA GUSSO ◽  
PAUL L. HOFMAN ◽  
JAMES C. BALDI
Keyword(s):  
Type 2 Diabetes ◽  
Blood Flow ◽  
Submaximal Exercise ◽  
Leg Blood Flow

Leg Blood Flow during Exercise in Man

1971 ◽  
Vol 41 (5) ◽  
pp. 459-473 ◽  
Author(s):  
L. Jorfeldt ◽  
J. Wahren
Keyword(s):  
Blood Flow ◽  
Oxygen Uptake ◽  
Femoral Vein ◽  
Mechanical Efficiency ◽  
Bicycle Ergometer ◽  
Work Intensity ◽  
Pulmonary Oxygen Uptake ◽  
Leg Blood Flow ◽  
Linear Relationships ◽  
Oxygen Difference

1. An indicator-dilution technique was used to determine human leg blood flow at rest and during exercise. The method is based on the infusion of Indocyanine Green into the femoral artery with blood sampling from the femoral vein at the level of the inguinal ligament. Evidence for mixing of dye and blood is presented, based on the finding of equal dye concentrations at two different sampling levels in the femoral vein. The minimum time of infusion required for equilibration at rest is 3 min and during exercise 1 min 20 s. 2. Leg blood flow was measured in eight healthy athletic subjects at rest and during upright exercise on a bicycle ergometer at 400, 800 and 1200 kpm/min. Linear relationships were found between blood flow on the one hand and work intensity and pulmonary oxygen uptake on the other. 3. Leg oxygen uptake was measured as the product of blood flow and femoral arterio-venous oxygen difference. Linear regressions were found for leg oxygen uptake in relation to both work intensity and pulmonary oxygen uptake. Leg mechanical efficiency during exercise averaged 34%. 4. A formula for the approximate calculation of leg blood flow is suggested, based on the pulmonary oxygen uptake and the femoral arterio-venous oxygen difference.

Prior exercise and postprandial substrate extraction across the human leg

2000 ◽  
Vol 279 (5) ◽  
pp. E1020-E1028 ◽  
Author(s):  
D. Malkova ◽  
R. D. Evans ◽  
K. N. Frayn ◽  
S. M. Humphreys ◽  
P. R. M. Jones ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Oxygen Uptake ◽  
Venous Blood ◽  
Postprandial Lipemia ◽  
Fasting State ◽  
Lower Plasma ◽  
Leg Blood Flow ◽  
Prior Exercise ◽  
Plasma Triacylglycerol

Prior exercise decreases postprandial plasma triacylglycerol (TG) concentrations, possibly through changes to skeletal muscle TG extraction. We measured postprandial substrate extraction across the leg in eight normolipidemic men aged 21–46 yr. On the afternoon preceding one trial, subjects ran for 2 h at 64 ± 1% of maximal oxygen uptake (exercise); before the control trial, subjects had refrained from exercise. Samples of femoral arterial and venous blood were obtained, and leg blood flow was measured in the fasting state and for 6 h after a meal (1.2 g fat, 1.2 g carbohydrate/kg body mass). Prior exercise increased time averaged postprandial TG clearance across the leg (total TG: control, 0.079 ± 0.014 ml · 100 ml tissue−1 · min−1; exercise, 0.158 ± 0.023 ml · 100 ml tissue−1 · min−1, P<0.01), particularly in the chylomicron fraction, so that absolute TG uptake was maintained despite lower plasma TG concentrations (control, 1.53 ± 0.13 mmol/l; exercise, 1.01 ± 0.16 mmol/l, P < 0.001). Prior exercise increased postprandial leg blood flow and glucose uptake (both P < 0.05). Mechanisms other than increased leg TG uptake must account for the effect of prior exercise on postprandial lipemia.

The Effects of Localized Hypoventilation on Ventilation/Perfusion Ratios and Gas Exchange in the Dog Lung

1982 ◽  
Vol 63 (6) ◽  
pp. 497-503 ◽  
Author(s):  
A. J. Suggett ◽  
Gwenda R. Barer ◽  
F. H. Mohammed ◽  
G. W. Gill
Keyword(s):  
Blood Flow ◽  
Gas Exchange ◽  
Pulmonary Artery ◽  
Oxygen Uptake ◽  
Pulmonary Artery Pressure ◽  
Dead Space ◽  
Respiratory Exchange Ratio ◽  
Plateau Phase ◽  
Flow Reduction ◽  
Co2 Output

1. Hypoventilation of one lobe of lung was studied in open-chest anaesthetized dogs. Lobar blood flow, pulmonary-artery pressure and gas exchange were measured, the latter from breath-by-breath analysis with a mass spectrometer. 2. Hypoventilation of the lobe by reducing the respiratory pump stroke led, at each step, to a reduction in blood flow to that lobe. The flow () reduction was variable, but always less than the ventilation () reduction, so that the ratio to the lobe was reduced. O2 tension and pH fell and CO2 tension rose in effluent blood. Thus regulation achieved by flow reduction varied between individuals and was of low gain. 3. Anatomical or series dead space (VD series) was reduced in proportion to ventilation. When VD series was less than the apparatus dead space, some gas exchange still took place. 4. Oxygen uptake () and CO2 output () were reduced during hypoventilation. fell more than , so that the respiratory exchange ratio (R) was reduced. 5. Whether the deterioration in gas tensions in effluent blood during hypoventilation of the lobe was due to shunt of blood past unventilated alveoli, or to mismatching, was not resolved. 6. The plateau phase of the CO2-output curves at low tidal volumes was usually regular; thus either hypoventilation was uniform, or some ventilation units were totally closed.

scholarly journals Differential responses of post-exercise recovery leg blood flow and oxygen uptake kinetics in HFPEF versus HFREF

2016 ◽  
Vol 18 (Suppl 1) ◽  
pp. O9 ◽  
Author(s):  
Richard B Thompson ◽  
Joseph J Pagano ◽  
Ian Paterson ◽  
Jason Dyck ◽  
Dalane Kitzman ◽  
...  
Keyword(s):  
Blood Flow ◽  
Oxygen Uptake ◽  
Oxygen Uptake Kinetics ◽  
Uptake Kinetics ◽  
Exercise Recovery ◽  
Post Exercise ◽  
Leg Blood Flow ◽  
Differential Responses ◽  
Post Exercise Recovery
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