scholarly journals Substantial elevation of interleukin‐6 concentration in peritendinous tissue, in contrast to muscle, following prolonged exercise in humans

2002 ◽  
Vol 542 (3) ◽  
pp. 985-990 ◽  
Author(s):  
Henning Langberg ◽  
Jens L. Olesen ◽  
Carsten Gemmer ◽  
Michael Kjær
Keyword(s):  
Interleukin 6 ◽  
Prolonged Exercise ◽  
Exercise In Humans

scholarly journals Cerebral ammonia uptake and accumulation during prolonged exercise in humans

2005 ◽  
Vol 563 (1) ◽  
pp. 285-290 ◽  
Author(s):  
Lars Nybo ◽  
Mads K. Dalsgaard ◽  
Adam Steensberg ◽  
Kirsten Møller ◽  
Niels H. Secher
Keyword(s):  
Prolonged Exercise ◽  
Ammonia Uptake ◽  
Exercise In Humans

Neurohumoral responses during prolonged exercise in humans

2003 ◽  
Vol 95 (3) ◽  
pp. 1125-1131 ◽  
Author(s):  
Lars Nybo ◽  
Bodil Nielsen ◽  
Eva Blomstrand ◽  
Kirsten Møller ◽  
Niels Secher
Keyword(s):  
Perceived Exertion ◽  
Prolonged Exercise ◽  
Strenuous Exercise ◽  
Trained Subjects ◽  
Perception Of Effort ◽  
Arteriovenous Difference ◽  
The Brain ◽  
Oxygen Difference ◽  
Net Release ◽  
Exercise In Humans

This study examined neurohumoral alterations during prolonged exercise with and without hyperthermia. The cerebral oxygen-to-carbohydrate uptake ratio (O2/CHO = arteriovenous oxygen difference divided by arteriovenous glucose difference plus one-half lactate), the cerebral balances of dopamine, and the metabolic precursor of serotonin, tryptophan, were evaluated in eight endurance-trained subjects during exercise randomized to be with or without hyperthermia. The core temperature stabilized at 37.9 ± 0.1°C (mean ± SE) in the control trial, whereas it increased to 39.7 ± 0.2°C in the hyperthermic trial, with a concomitant increase in perceived exertion ( P < 0.05). At rest, the brain had a small release of tryptophan (arteriovenous difference of -1.2 ± 0.3 μmol/l), whereas a net balance was obtained during the two exercise trials. Both the arterial and jugular venous dopamine levels became elevated during the hyperthermic trial, but the net release from the brain was unchanged. During exercise, the O2/CHO was similar across trials, but, during recovery from the hyperthermic trial, the ratio decreased to 3.8 ± 0.3 ( P < 0.05), whereas it returned to the baseline level of ∼6 within 5 min after the control trial. The lowering of O2/CHO was established by an increased arteriovenous glucose difference (1.1 ± 0.1 mmol/l during recovery from hyperthermia vs. 0.7 ± 0.1 mmol/l in control; P < 0.05). The present findings indicate that the brain has an increased need for carbohydrates during recovery from strenuous exercise, whereas enhanced perception of effort as observed during exercise with hyperthermia was not related to alterations in the cerebral balances of dopamine or tryptophan.

Effect of elevated FFA on carbohydrate and lipid oxidation during prolonged exercise in humans

1986 ◽  
Vol 60 (3) ◽  
pp. 893-900 ◽  
Author(s):  
E. Ravussin ◽  
C. Bogardus ◽  
K. Scheidegger ◽  
B. LaGrange ◽  
E. D. Horton ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Energy Expenditure ◽  
Total Energy ◽  
Prolonged Exercise ◽  
Total Energy Expenditure ◽  
Constant Infusion ◽  
Base Line ◽  
O2 Uptake ◽  
Glucose Ingestion ◽  
Exercise In Humans

Increased availability of circulating free fatty acids (FFA) inhibits the rate of glycolysis in heart and resting skeletal muscle (Randle effect). Whether elevated FFA may play a role in decreasing carbohydrate oxidation during prolonged exercise in humans is more controversial. Using respiratory exchange measurements, we measured substrate utilization during 2.5 h of exercise at approximately 44 +/- 1% maximal O2 uptake (VO2 max) in the presence or absence of elevated FFA levels. After 30 min of base-line determinations, 1,000 U heparin was given intravenously and a 3-h constant infusion of Intralipid 10% (150 g/h) and heparin (500 U/h) was started. After an additional 30 min of rest, subjects exercised for 2.5 h (study 1, n = 6). In another five subjects (study 2) 100 g glucose was ingested after 30 min of exercise. The same protocols (studies 1 and 2) were also performed during a 0.9%-saline infusion. During exercise, without glucose ingestion, higher FFA concentrations prevailed during the Intralipid infusion (1,122 +/- 40 vs. 782 +/- 65 mumol/l), but the relative contributions of carbohydrate (49 +/- 4 vs. 50 +/- 4%) or lipid (49 +/- 4 vs. 47 +/- 6%) oxidation to the total energy expenditure were different only during the first 30 min of exercise. Similarly, higher FFA levels (1,032 +/- 62 vs. 568 +/- 46 mumol/l) did not alter the relative contributions of carbohydrate (62 +/- 4 vs. 69 +/- 2%) or lipid (36 +/- 4 vs. 29 +/- 2%) oxidation to the total energy expenditure after glucose feeding.(ABSTRACT TRUNCATED AT 250 WORDS)

Caffeine ingestion and muscle metabolism during prolonged exercise in humans

1992 ◽  
Vol 262 (6) ◽  
pp. E891-E898 ◽  
Author(s):  
L. L. Spriet ◽  
D. A. MacLean ◽  
D. J. Dyck ◽  
E. Hultman ◽  
G. Cederblad ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Prolonged Exercise ◽  
Muscle Metabolism ◽  
Endurance Performance ◽  
Time To Exhaustion ◽  
Acetyl Coa ◽  
Caffeine Ingestion ◽  
Acetyl Group ◽  
Muscle Biopsies ◽  
Exercise In Humans

We examined the effects of a high-caffeine dose on endurance performance and muscle acetyl group metabolism during prolonged exercise. Eight subjects cycled to exhaustion at approximately 80% maximal oxygen uptake (VO2max) 1 h after ingestion of 9 mg/kg body wt dextrose (Pl) or caffeine (Caf). In the Pl trial, muscle biopsies were taken at rest (1 h postingestion) and at 15 min and exhaustion during exercise. The Caf trial followed the same protocol 1 wk later, with an additional biopsy at the time corresponding to Pl exhaustion. The subjects cycled significantly longer during the Caf trial (96.2 +/- 8.8 min) than in the Pl trial (75.8 +/- 4.8 min). Net glycogenolysis during the initial 15 min of cycling was reduced in the Caf vs. Pl trial (4.7 +/- 1.5 vs. 10.6 +/- 1.3 mmol.kg dry muscle-1.min-1; P less than 0.05). Muscle citrate concentration was increased at rest with Caf (0.59 +/- 0.07 vs. 0.37 +/- 0.05 mmol/kg dry muscle; P less than 0.05) but increased to similar values in both trials during cycling. Caf elevated the acetyl-CoA/CoA-SH ratio at rest (0.316 +/- 0.046 vs. 0.201 +/- 0.023; P less than 0.05) but had no effect on the increases in muscle acetyl-CoA and acetylcarnitine during exercise. The results indicate that Caf before exercise decreased muscle glycogenolysis by approximately 55% over the first 15 min of exercise at approximately 80% VO2max. This "spared glycogen" was available late in exercise and coincided with a prolonged time to exhaustion. Increased utilization of intramuscular triacylglycerol and/or extramuscular free fatty acids after caffeine ingestion may inhibit carbohydrate use at rest and early during exercise via elevations in muscle citrate and the acetyl-CoA/CoA-SH ratio. Muscle acetyl-CoA and acetylcarnitine were maintained above resting contents even at exhaustion when muscle glycogen was depleted.

Plasma and muscle amino acid and ammonia responses during prolonged exercise in humans

1991 ◽  
Vol 70 (5) ◽  
pp. 2095-2103 ◽  
Author(s):  
D. A. MacLean ◽  
L. L. Spriet ◽  
E. Hultman ◽  
T. E. Graham
Keyword(s):  
Amino Acid ◽  
Prolonged Exercise ◽  
Vastus Lateralis ◽  
Submaximal Exercise ◽  
Protein Catabolism ◽  
O2 Uptake ◽  
Purine Nucleotide Cycle ◽  
Branched Chain ◽  
Muscle Biopsies ◽  
Exercise In Humans

Plasma and muscle amino acid (AA) and ammonia (NH3) responses were measured during prolonged submaximal exercise in humans. Increased NH3 production during submaximal exercise has been attributed to the activity of the purine nucleotide cycle, without consideration of any possible contribution from AA. Six men cycled at 75% of maximal O2 uptake until exhaustion on two occasions after 2.5 days of ingestion of a high-carbohydrate or mixed diet. Plasma samples (antecubital vein) and muscle biopsies (vastus lateralis) were obtained at rest and during exercise and analyzed for plasma and muscle NH3 and AA as well as muscle metabolites. There were no significant diet effects in these parameters, so the majority of results focus on the effects of exercise. Plasma and muscle NH3 increased significantly from the onset and continued to increase throughout exercise. The total and total essential [AA] of muscle were significantly increased at exhaustion, whereas both the plasma and muscle branched-chain AA contents were unchanged. This suggests that protein catabolism was occurring during exercise and the branched-chain AA were used for energy and NH3 production.

scholarly journals Erythropoietin enhances whole body lipid oxidation during prolonged exercise in humans

2015 ◽  
Vol 71 (1) ◽  
pp. 9-16 ◽  
Author(s):  
Corinne Caillaud ◽  
Philippe Connes ◽  
Helmi Ben Saad ◽  
Jacques Mercier
Keyword(s):  
Lipid Oxidation ◽  
Prolonged Exercise ◽  
Whole Body ◽  
Body Lipid ◽  
Exercise In Humans

769 EFFECTS OF AGE ON THE CIRCULATORY AND THERMAL ADJUSTMENTS TO PROLONGED EXERCISE IN HUMANS

1994 ◽  
Vol 26 (Supplement) ◽  
pp. S137
Author(s):  
Mary Jo Reiling ◽  
Kevin P. Davy ◽  
Douglas R. Seals
Keyword(s):  
Prolonged Exercise ◽  
Exercise In Humans
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