Muscle blood flow and muscle metabolism during exercise and heat stress
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Muscle blood flow and muscle metabolism during exercise and heat stress. / Nielsen, Bodil; Savard, G; Richter, Erik A.; Hargreaves, Mark; Saltin, Bengt.
I: Journal of Applied Physiology, Bind 69, Nr. 3, 1990, s. 1040-1046.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › fagfællebedømt
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TY - JOUR
T1 - Muscle blood flow and muscle metabolism during exercise and heat stress
AU - Nielsen, Bodil
AU - Savard, G
AU - Richter, Erik A.
AU - Hargreaves, Mark
AU - Saltin, Bengt
PY - 1990
Y1 - 1990
N2 - The effect of heat stress on blood flow and metabolism in an exercising leg was studied in seven subjects walking uphill (12-17%) at 5 km/h on a treadmill for 90 min or until exhaustion. The first 30 min of exercise were performed in a cool environment (18-21 degrees C); then subjects moved to an adjacent room at 40 degrees C and continued to exercise at the same speed and inclination for a further 60 min or to exhaustion, whichever occurred first. The rate of O2 consumption, 2.6 l/min (1.8-3.3) (average from cool and hot conditions), corresponded to 55-77% of their individual maximums. In the cool environment a steady state was reached at 30 min. When the subjects were shifted to the hot room, the core temperature and heart rate started to rise and reached values greater than 39 degrees C and near-maximal values, respectively, at the termination of the exercise. The leg blood flow (thermodilution method), femoral arteriovenous O2 difference, and consequently leg O2 consumption were unchanged in the hot compared with the cool condition. There was no increase in release of lactate and no reduction in glucose and free net fatty acid uptake in the exercising leg in the heat. Furthermore, the rate of glycogen utilization in the gastrocnemius muscle was not elevated in the hot environment. There was a tendency for cardiac output to increase in the heat (mean 15.2 to 18.4 l/min), which may have contributed to the increase in skin circulation, together with a possible further reduction in flow to other vascular beds, because muscle blood flow was not reduced.(ABSTRACT TRUNCATED AT 250 WORDS)
AB - The effect of heat stress on blood flow and metabolism in an exercising leg was studied in seven subjects walking uphill (12-17%) at 5 km/h on a treadmill for 90 min or until exhaustion. The first 30 min of exercise were performed in a cool environment (18-21 degrees C); then subjects moved to an adjacent room at 40 degrees C and continued to exercise at the same speed and inclination for a further 60 min or to exhaustion, whichever occurred first. The rate of O2 consumption, 2.6 l/min (1.8-3.3) (average from cool and hot conditions), corresponded to 55-77% of their individual maximums. In the cool environment a steady state was reached at 30 min. When the subjects were shifted to the hot room, the core temperature and heart rate started to rise and reached values greater than 39 degrees C and near-maximal values, respectively, at the termination of the exercise. The leg blood flow (thermodilution method), femoral arteriovenous O2 difference, and consequently leg O2 consumption were unchanged in the hot compared with the cool condition. There was no increase in release of lactate and no reduction in glucose and free net fatty acid uptake in the exercising leg in the heat. Furthermore, the rate of glycogen utilization in the gastrocnemius muscle was not elevated in the hot environment. There was a tendency for cardiac output to increase in the heat (mean 15.2 to 18.4 l/min), which may have contributed to the increase in skin circulation, together with a possible further reduction in flow to other vascular beds, because muscle blood flow was not reduced.(ABSTRACT TRUNCATED AT 250 WORDS)
KW - Adult
KW - Energy Metabolism
KW - Exercise
KW - Glycogen
KW - Hot Temperature
KW - Humans
KW - Lactates
KW - Male
KW - Muscles
KW - Oxygen Consumption
KW - Regional Blood Flow
KW - Stress, Physiological
M3 - Journal article
C2 - 2246151
VL - 69
SP - 1040
EP - 1046
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
SN - 8750-7587
IS - 3
ER -
ID: 154755918