Sparing effect of chronic high-altitude exposure on muscle glycogen utilization

1982 ◽  
Vol 52 (4) ◽  
pp. 857-862 ◽  
Author(s):  
A. J. Young ◽  
W. J. Evans ◽  
A. Cymerman ◽  
K. B. Pandolf ◽  
J. J. Knapik ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
High Altitude ◽  
Muscle Glycogen ◽  
Vastus Lateralis ◽  
Venous Blood ◽  
Vastus Lateralis Muscle ◽  
Before And After ◽  
Glycogen Utilization ◽  
Sparing Effect

Substrate utilization during heavy [approximately 85% maximum O2 consumption (VO2max)] bicycle exercise was examined in eight low-altitude residents at sea level (SL) and after acute (2 h) and chronic (18 days) high-altitude (HA) exposure at 4,300 m. Mean VO2max was approximately 27% lower at acute HA than at SL and did not change significantly with continued HA exposure. Biopsies from the vastus lateralis muscle and venous blood samples were obtained before and after 30 min of exercise, whereas determinations of the respiratory exchange ratio (R) were made at 10-min intervals during each of the submaximal bouts. Resting levels of serum-free fatty acids at acute and chronic HA were, respectively, two and three times higher than SL but were unchanged with exercise. Exercise did not alter resting serum glycerol levels at SL or during acute HA, but during chronic HA resting glycerol levels were increased 11-fold. Although mean blood lactate concentrations following exercise at SL and acute HA were not significantly different, postexercise lactate concentrations were 87% lower after chronic HA. During exercise at SL and acute HA, muscle glycogen utilization and R were not different. At chronic HA, muscle glycogen utilization and R were 41 and 15% lower, respectively. These data suggest that after chronic HA exposure, increased mobilization and use of free fatty acids during exercise resulted in sparing of muscle glycogen.

scholarly journals A sparing effect of increased plasma fatty acids on muscle and liver glycogen content in the exercising rat

1976 ◽  
Vol 156 (3) ◽  
pp. 647-655 ◽  
Author(s):  
M J Rennie ◽  
W W Winder ◽  
J O Holloszy
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
Vastus Lateralis ◽  
Liver Glycogen ◽  
Vastus Lateralis Muscle ◽  
Glycogen Depletion ◽  
Plasma Insulin Concentration ◽  
Plasma Free Fatty Acids ◽  
Sparing Effect ◽  
Exercise Induced

Increasing plasma free fatty acids decreased the degree of glycogen depletion, and increased the citrate concentration, in slow-red (soleus) and fast-red (deep portion of vastus lateralis) muscle during exercise (approx. 50% depletion of glycogen, as against 75% in control animals). There was no effect in fast-white muscle (superficial portion of vastus lateralis). Glycogen concentration in the liver decreased by 83% in controls, but only by 23% in animals with increased free fatty acids during exercise. The decreased glycogen depletion may be partly explained by the findings that (a) plasma-insulin concentration was two- to three-fold higher in animals with increased plasma free fatty acids and (b) the exercise-induced increase in plasma glucagon was lessened by increased free fatty acids. Blood glucose was higher in the animals with increased free fatty acids after the exercise. The rats with increased plasma free fatty acids utilized approx. 50% as much carbohydrate as did the controls during the exercise.

Muscle glycogen availability and temperature regulation in humans

1989 ◽  
Vol 66 (1) ◽  
pp. 72-78 ◽  
Author(s):  
L. Martineau ◽  
I. Jacobs
Keyword(s):  
Skeletal Muscle ◽  
Muscle Glycogen ◽  
Temperature Regulation ◽  
Vastus Lateralis ◽  
Water Immersion ◽  
Vastus Lateralis Muscle ◽  
Glycogen Concentration ◽  
Exercise Regimen ◽  
Before And After ◽  
Muscle Groups

The effects of intramuscular glycogen availability on human temperature regulation were studied in eight seminude subjects immersed in 18 degrees C water for 90 min or until rectal temperature (Tre) decreased to 35.5 degrees C. Each subject was immersed three times over a 3-wk period. Each immersion followed 2.5 days of a specific dietary and/or exercise regimen designed to elicit low (L), normal (N), or high (H) glycogen levels in large skeletal muscle groups. Muscle glycogen concentration was determined in biopsies taken from the vastus lateralis muscle before and after each immersion. Intramuscular glycogen concentration before the immersion was significantly different among the L, N, and H trials (P less than 0.01), averaging 247 +/- 15, 406 +/- 23, and 548 +/- 42 (SE) mmol glucose units.kg dry muscle-1, respectively. The calculated metabolic heat production during the first 30 min of immersion was significantly lower during L compared with N or H (P less than 0.05). The rate at which Tre decreased was more rapid during the L immersion than either N or H (P less than 0.05), and the time during the immersion at which Tre first began to decrease also appeared sooner during L than N or H. The results suggest that low skeletal muscle glycogen levels are associated with more rapid body cooling during water immersion in humans. Higher than normal muscle glycogen levels, however, do not increase cold tolerance.

Effect of carbohydrate ingestion on exercise metabolism

1988 ◽  
Vol 65 (4) ◽  
pp. 1553-1555 ◽  
Author(s):  
M. Hargreaves ◽  
C. A. Briggs
Keyword(s):  
Muscle Glycogen ◽  
Venous Blood ◽  
Cycle Ergometer ◽  
Strenuous Exercise ◽  
Carbohydrate Ingestion ◽  
Ergometer Exercise ◽  
Glucose Polymer ◽  
Before And After ◽  
Plasma Insulin Levels ◽  
Glycogen Utilization

Five male cyclists were studied during 2 h of cycle ergometer exercise (70% VO2 max) on two occasions to examine the effect of carbohydrate ingestion on muscle glycogen utilization. In the experimental trial (CHO) subjects ingested 250 ml of a glucose polymer solution containing 30 g of carbohydrate at 0, 30, 60, and 90 min of exercise; in the control trial (CON) they received an equal volume of a sweet placebo. No differences between trials were seen in O2 uptake or heart rate during exercise. Venous blood glucose was similar before exercise in both trials, but, on average, was higher during exercise in CHO [5.2 +/- 0.2 (SE) mmol/l] compared with CON (4.8 +/- 0.1, P less than 0.05). Plasma insulin levels were similar in both trials. Muscle glycogen levels were also similar in CHO and CON both before and after exercise; accordingly, there was no difference between trials in the amount of glycogen used during the 2 h of exercise (CHO = 62.8 +/- 10.1 mmol/kg wet wt, CON = 56.9 +/- 10.1). The results of this study indicate that carbohydrate ingestion does not influence the utilization of muscle glycogen during prolonged strenuous exercise.

Muscle glycogen utilization during shivering thermogenesis in humans

1988 ◽  
Vol 65 (5) ◽  
pp. 2046-2050 ◽  
Author(s):  
L. Martineau ◽  
I. Jacobs
Keyword(s):  
Skeletal Muscle ◽  
Muscle Glycogen ◽  
Cold Water ◽  
Vastus Lateralis ◽  
Water Immersion ◽  
Venous Blood ◽  
Cold Water Immersion ◽  
Vastus Lateralis Muscle ◽  
Glucose Levels ◽  
Shivering Thermogenesis

The purpose of the present study was to clarify the importance of skeletal muscle glycogen as a fuel for shivering thermogenesis in humans during cold-water immersion. Fourteen seminude subjects were immersed to the shoulders in 18 degrees C water for 90 min or until rectal temperature (Tre) decreased to 35.5 degrees C. Biopsies from the vastus lateralis muscle and venous blood samples were obtained before and immediately after the immersion. Metabolic rate increased during the immersion to 3.5 +/- 0.3 (SE) times resting values, whereas Tre decreased by 0.9 degrees C to approximately 35.8 degrees C at the end of the immersion. Intramuscular glycogen concentration in the vastus lateralis decreased from 410 +/- 15 to 332 +/- 18 mmol glucose/kg dry muscle, with each subject showing a decrease (P less than 0.001). Plasma volume decreased (P less than 0.001) markedly during the immersion (-24 +/- 1%). After correcting for this decrease, blood lactate and plasma glycerol levels increased by 60 (P less than 0.05) and 38% (P less than 0.01), respectively, whereas plasma glucose levels were reduced by 20% after the immersion (P less than 0.001). The mean expiratory exchange ratio showed a biphasic pattern, increasing initially during the first 30 min of the immersion from 0.80 +/- 0.06 to 0.85 +/- 0.05 (P less than 0.01) and decreasing thereafter toward basal values. The results demonstrate clearly that intramuscular glycogen reserves are used as a metabolic substrate to fuel intensive thermogenic shivering activity of human skeletal muscle.

scholarly journals Muscle Glycogen Utilization During an Australian Rules Football Game

2019 ◽  
Vol 14 (1) ◽  
pp. 122-124 ◽  
Author(s):  
Harry E. Routledge ◽  
Jill J. Leckey ◽  
Matt J. Lee ◽  
Andrew Garnham ◽  
Stuart Graham ◽  
...  
Keyword(s):  
Muscle Glycogen ◽  
High Speed ◽  
Fiber Type ◽  
Vastus Lateralis ◽  
Dry Weight ◽  
Match Play ◽  
Australian Football League ◽  
Before And After ◽  
Australian Football ◽  
Glycogen Utilization

Purpose: To better understand the carbohydrate (CHO) requirement of Australian Football (AF) match play by quantifying muscle glycogen utilization during an in-season AF match. Methods: After a 24-h CHO-loading protocol of 8 and 2 g/kg in the prematch meal, 2 elite male forward players had biopsies sampled from m. vastus lateralis before and after participation in a South Australian Football League game. Player A (87.2 kg) consumed water only during match play, whereas player B (87.6 kg) consumed 88 g CHO via CHO gels. External load was quantified using global positioning system technology. Results: Player A completed more minutes on the ground (115 vs 98 min) and covered greater total distance (12.2 vs 11.2 km) than player B, although with similar high-speed running (837 vs 1070 m) and sprinting (135 vs 138 m). Muscle glycogen decreased by 66% in player A (pre: 656 mmol/kg dry weight [dw], post: 223 mmol/kg dw) and 24% in player B (pre: 544 mmol/kg dw, post: 416 mmol/kg dw). Conclusion: Prematch CHO loading elevated muscle glycogen concentrations (ie, >500 mmol/kg dw), the magnitude of which appears sufficient to meet the metabolic demands of elite AF match play. The glycogen cost of AF match play may be greater than in soccer and rugby, and CHO feeding may also spare muscle glycogen use. Further studies using larger sample sizes are now required to quantify the interindividual variability of glycogen cost of match play (including muscle and fiber-type-specific responses), as well examining potential metabolic and ergogenic effects of CHO feeding.

scholarly journals Regular Dark Chocolate Consumption’s Reduction of Oxidative Stress and Increase of Free-Fatty-Acid Mobilization in Response to Prolonged Cycling

2011 ◽  
Vol 21 (2) ◽  
pp. 113-123 ◽  
Author(s):  
Judith Allgrove ◽  
Emily Farrell ◽  
Michael Gleeson ◽  
Gary Williamson ◽  
Karen Cooper
Keyword(s):  
Oxidative Stress ◽  
Fatty Acids ◽  
Free Fatty Acids ◽  
Treatment Time ◽  
Venous Blood ◽  
Dark Chocolate ◽  
Plasma Metabolites ◽  
Time To Exhaustion ◽  
Before And After ◽  
Markers Of Oxidative Stress

This study investigated the effects of regular consumption of dark chocolate (DC), rich in cocoa polyphenols, on plasma metabolites, hormones, and markers of oxidative stress after prolonged exhaustive exercise. Twenty active men cycled at 60% maximal oxygen uptake (VO2max) for 1.5 hr, with the intensity increased to 90% VO2max for a 30-s period every 10 min, followed by a ride to exhaustion at 90% VO2max. In the 2 wk before exercise participants consumed 40 g of DC or an isocarbohydrate-fat control cocoa liquor–free chocolate (CON) twice daily and once 2 hr before exercise in a randomized, counterbalanced, crossover design. Venous blood samples were taken immediately before exercise, postexercise (fixed duration), postexhaustion, and after 1 hr of recovery. F2-isoprostanes were significantly lower (post hoc tests: p < .001) at exhaustion and after 1 hr of recovery with DC. Oxidized low-density lipoproteins were significantly lower with DC (p < .001) both before and after exercise and at exhaustion. DC was also associated with ~21% greater rises in free fatty acids during exercise (main effect: p < .05). Changes in circulating glucose, insulin, glucagon, cortisol, and interleukin (IL)-6, IL-10, and IL-1ra were unaffected by treatment. Time to exhaustion at 90% VO2max was not significantly different between trials (398 ± 204 and 374 ± 194 s for DC and CON, respectively). These results suggest that regular DC intake is associated with reduced oxidative-stress markers and increased mobilization of free fatty acids after exercise but has no observed effect on exercise performance.

Muscle structure and performance capacity of Himalayan Sherpas

1991 ◽  
Vol 70 (5) ◽  
pp. 1938-1942 ◽  
Author(s):  
B. Kayser ◽  
H. Hoppeler ◽  
H. Claassen ◽  
P. Cerretelli
Keyword(s):  
High Altitude ◽  
Vastus Lateralis ◽  
Volume Ratio ◽  
Volume Density ◽  
Vastus Lateralis Muscle ◽  
O2 Consumption ◽  
Cross Sectional ◽  
Before And After ◽  
Mitochondrial Volume ◽  
And Performance

The ultrastructure of the vastus lateralis muscle of Sherpas from Nepal [5 males; age 28 +/- 2.8 (SD) yr, indirect maximal O2 consumption 48.5 +/- 5.4 ml.kg(-1).min(-1)] was assessed and compared with those of sedentary lowlanders and of Caucasian climbers before and after high-altitude exposure. The mean cross-sectional area of the fibers was 3,186 +/- 521 microns2, i.e., similar to those of Caucasian elite high-altitude climbers (3,108 +/- 303 microns2) and a group of climbers after a 6- to 8-wk sojourn at 5,000-8,600 m (3,360 +/- 580 microns2) but significantly (P less than 0.05) smaller than that of unacclimatized climbers (4,170 +/- 710 microns2) and slightly, although not significantly, lower than that of sedentary lowlanders (3,640 +/- 260 microns2). The number of capillaries per square millimeter of muscle cross section was 467 +/- 22, not significantly smaller than those of climbers on return from a Himalayan expedition (538 +/- 89) and elite high-altitude climbers (542 +/- 127) but significantly (P less than 0.05) greater than that of sedentary lowlanders (387 +/- 25). The volume density of mitochondria was 3.96 +/- 0.54%, significantly (P less than 0.05) less than the values found for any other investigated group, including sedentary subjects at sea level (4.74 +/- 0.30%). It is concluded that Sherpas, like acclimatized Caucasian climbers, are characterized by 1) facilitated convective and diffusive muscle O2 flow conditions and 2) a higher maximal O2 consumption-to-mitochondrial volume ratio than lowlanders despite a reduced mitochondrial volume density.

Muscle glycogen utilization during prolonged strenuous exercise when fed carbohydrate

1986 ◽  
Vol 61 (1) ◽  
pp. 165-172 ◽  
Author(s):  
E. F. Coyle ◽  
A. R. Coggan ◽  
M. K. Hemmert ◽  
J. L. Ivy
Keyword(s):  
Plasma Glucose ◽  
Muscle Glycogen ◽  
Average Rate ◽  
Water Solution ◽  
Vastus Lateralis ◽  
Carbohydrate Oxidation ◽  
Strenuous Exercise ◽  
Vastus Lateralis Muscle ◽  
Glycogen Depletion ◽  
Glycogen Utilization

The purpose of this study was to determine whether the postponement of fatigue in subjects fed carbohydrate during prolonged strenuous exercise is associated with a slowing of muscle glycogen depletion. Seven endurance-trained cyclists exercised at 71 +/- 1% of maximal O2 consumption (VO2max), to fatigue, while ingesting a flavored water solution (i.e., placebo) during one trial and while ingesting a glucose polymer solution (i.e., 2.0 g/kg at 20 min and 0.4 g/kg every 20 min thereafter) during another trial. Fatigue during the placebo trial occurred after 3.02 +/- 0.19 h of exercise and was preceded by a decline (P less than 0.01) in plasma glucose to 2.5 +/- 0.5 mM and by a decline in the respiratory exchange ratio (i.e., R; from 0.85 to 0.80; P less than 0.05). Glycogen within the vastus lateralis muscle declined at an average rate of 51.5 +/- 5.4 mmol glucosyl units (GU) X kg-1 X h-1 during the first 2 h of exercise and at a slower rate (P less than 0.01) of 23.0 +/- 14.3 mmol GU X kg-1 X h-1 during the third and final hour. When fed carbohydrate, which maintained plasma glucose concentration (4.2–5.2 mM), the subjects exercised for an additional hour before fatiguing (4.02 +/- 0.33 h; P less than 0.01) and maintained their initial R (i.e., 0.86) and rate of carbohydrate oxidation throughout exercise. The pattern of muscle glycogen utilization, however, was not different during the first 3 h of exercise with the placebo or the carbohydrate feedings. The additional hour of exercise performed when fed carbohydrate was accomplished with little reliance on muscle glycogen (i.e., 5 mmol GU X kg-1 X h-1; NS) and without compromising carbohydrate oxidation. We conclude that when they are fed carbohydrate, highly trained endurance athletes are capable of oxidizing carbohydrate at relatively high rates from sources other than muscle glycogen during the latter stages of prolonged strenuous exercise and that this postpones fatigue.

The Role of Medium-Chain Triglycerides in Exercise

1996 ◽  
Vol 6 (2) ◽  
pp. 121-133 ◽  
Author(s):  
Jacqueline R. Berning
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
Muscle Glycogen ◽  
Prolonged Exercise ◽  
Medium Chain Triglycerides ◽  
Medium Chain ◽  
Alternative Carbon Source ◽  
Sparing Effect ◽  
Fuel Source

Studies investigating fat as a fuel for exercise have found that increasing free fatty acids during exercise tends to spare muscle glycogen due to increased utilization of free fatty acids for energy, which in turn can enhance the capacity for endurance exercise. Medium-chain triglycerides do not delay gastric emptying or absorption. They are broken down by lipase in the stomach and duodenum to glycerol and medium-chain fatty acids (MCFA). Since MCFAs are metabolized as quickly as glucose, it has been speculated that they might provide an alternative carbon source for the muscle during prolonged exercise. While the majority of studies investigating the role of medium-chain triglycerides and exercise have found no sparing effect of muscle glycogen after consumption of medium-chain triglycerides, two recent studies have presented conflicting results. This review will investigate the speculated role of medium-chain triglycerides as an alternative fuel source for exercising muscles and will discuss the possibility that medium-chain triglycerides preserve muscle glycogen during exercise,

Assessment of cancer prevention effect of exercise

2021 ◽  
pp. 1-6
Author(s):  
Reza Vafaee ◽  
Mostafa Rezaei Tavirani ◽  
Sina Rezaei Tavirani ◽  
Mohammadreza Razzaghi
Keyword(s):  
Gene Expression ◽  
Cancer Prevention ◽  
Human Health ◽  
Expression Profiles ◽  
Vastus Lateralis ◽  
Gene Expression Profiles ◽  
Gene Expression Omnibus ◽  
Vastus Lateralis Muscle ◽  
Before And After ◽  
Exercise Training Intervention

There are many documents about benefits of exercise on human health. However, evidences indicate to positive effect of exercise on disease prevention, understanding of many aspects of this mechanism need more investigations. Determination of critical genes which effect human health. GSE156249 including 12 gene expression profiles of healthy individual biopsy from vastus lateralis muscle before and after 12-week combined exercise training intervention were extracted from gene expression omnibus (GEO) database. The significant DEGs were included in interactome unit by Cytoscape software and STRING database. The network was analyzed to find the central nodes subnetwork clusters. The nodes of prominent cluster were assessed via gene ontology by using ClueGO. Number of 8 significant DEGs and 100 first neighbors analyzed via network analysis. The network includes 2 clusters and COL3A1, BGN, and LOX were determined as central DEGs. The critical DEGs were involved in cancer prevention process.

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