scholarly journals Oxidative fuel selection and shivering thermogenesis during a 12- and 24-h cold-survival simulation

2016 ◽  
Vol 120 (6) ◽  
pp. 640-648 ◽  
Author(s):  
François Haman ◽  
Olivier L. Mantha ◽  
Stephen S. Cheung ◽  
Michel B. DuCharme ◽  
Michael Taber ◽  
...  
Keyword(s):  
Cold Exposure ◽  
Muscle Glycogen ◽  
Whole Body ◽  
Muscle Recruitment ◽  
Glycogen Depletion ◽  
Total Carbohydrate ◽  
Fuel Selection ◽  
Isotopic Methods ◽  
Shivering Thermogenesis

Because the majority of cold exposure studies are constrained to short-term durations of several hours, the long-term metabolic demands of cold exposure, such as during survival situations, remain largely unknown. The present study provides the first estimates of thermogenic rate, oxidative fuel selection, and muscle recruitment during a 24-h cold-survival simulation. Using combined indirect calorimetry and electrophysiological and isotopic methods, changes in muscle glycogen, total carbohydrate, lipid, protein oxidation, muscle recruitment, and whole body thermogenic rate were determined in underfed and noncold-acclimatized men during a simulated accidental exposure to 7.5°C for 12 to 24 h. In noncold-acclimatized healthy men, cold exposure induced a decrease of ∼0.8°C in core temperature and a decrease of ∼6.1°C in mean skin temperature (range, 5.4-6.9°C). Results showed that total heat production increased by approximately 1.3- to 1.5-fold in the cold and remained constant throughout cold exposure. Interestingly, this constant rise in Ḣprod and shivering intensity was accompanied by a large modification in fuel selection that occurred between 6 and 12 h; total carbohydrate oxidation decreased by 2.4-fold, and lipid oxidation doubled progressively from baseline to 24 h. Clearly, such changes in fuel selection dramatically reduces the utilization of limited muscle glycogen reserves, thus extending the predicted time to muscle glycogen depletion to as much as 15 days rather than the previous estimates of approximately 30–40 h. Further research is needed to determine whether this would also be the case under different nutritional and/or colder conditions.

Effects of the menstrual cycle on muscle recruitment and oxidative fuel selection during cold exposure

2011 ◽  
Vol 111 (4) ◽  
pp. 1014-1020 ◽  
Author(s):  
Denis P. Blondin ◽  
Anali Maneshi ◽  
Marie-Andrée Imbeault ◽  
François Haman
Keyword(s):  
Menstrual Cycle ◽  
Core Temperature ◽  
Heat Production ◽  
Total Heat ◽  
Whole Body ◽  
Large Contribution ◽  
Electromyographic Activity ◽  
Muscle Recruitment ◽  
Low Intensity ◽  
Fuel Selection

Differences in core temperature and body heat content, generally observed between the luteal and follicular phase of the menstrual cycle, have been reported to modulate the thermogenic activity of cold-exposed women. However, it is unclear how this change in whole body shivering activity will influence fuel selection. The goal of this study was to quantify the effects of the menstrual cycle on muscle recruitment and oxidative fuel selection during low-intensity shivering. Electromyographic activity of eight large muscles was monitored while carbohydrate, lipid, and protein utilization was simultaneously quantified in the follicular and luteal phases of the menstrual cycle in nonacclimatized women shivering at a low intensity. The onset (∼25 min), intensity (∼15% of maximal voluntary contraction), and pattern (∼6 shivering bursts/min) of the shivering response did not differ between menstrual cycle phases, regardless of differences in core temperature and hormone levels. This resulted in lipids remaining the predominant substrate, contributing 75% of total heat production, independent of menstrual phase. We conclude that hormone fluctuations inherent in the menstrual cycle do not affect mechanisms of substrate utilization in the cold. Whether the large contribution of lipids to total heat production in fuel selection confers a survival advantage remains to be established.

scholarly journals Muscle Glycogenolysis and Resynthesis in Response to a Half Ironman Triathlon: A Case Study

2006 ◽  
Vol 1 (4) ◽  
pp. 408-413 ◽  
Author(s):  
Trevor L. Gillum ◽  
Charles L. Dumke ◽  
Brent C. Ruby
Keyword(s):  
Body Weight ◽  
Energy Expenditure ◽  
Muscle Glycogen ◽  
Vastus Lateralis ◽  
High Rate ◽  
Whole Body ◽  
Glycogen Depletion ◽  
Glycogen Resynthesis ◽  
Wet Weight ◽  
Ironman Triathlon

Purpose:To describe the degrees of muscle-glycogen depletion and resynthesis in response to a half Ironman triathlon.Methods:One male subject (38 years of age) completed the Grand Columbian half Ironman triathlon (1.9-km swim, 90-km bike, 21.1-km run, Coulee City, Wash). Three muscle biopsies were obtained from his right vastus lateralis (prerace, immediately postrace, and 4 hours postrace). Prerace and postrace body weight were recorded, in addition to macronutrient consumption before, during, and after the race. Energy expenditure and whole-body substrate oxidation were estimated from linear regression established from laboratory trials (watts and run pace relative to VO2 and VCO2).Results:Body weight decreased 3.8 kg from prerace to postrace. Estimated CHO energy expenditure was 10,003 kJ for the bike segment and 5759 kJ for the run segment of the race. The athlete consumed 308 g of exogenous CHO (liquid and gel; 1.21 g CHO/min) during the race. Muscle glycogen decreased from 227.1 prerace to 38.6 mmol · kg wet weight−1 · h−1 postrace. During the 4 hours postrace, the athlete consumed a mixed diet (471 g CHO, 15 g fat, 64 g protein), which included liquid CHO sources and a meal. The calculated rate of muscle-glycogen resynthesis was 4.1 mmol · kg wet weight−1 · h−1.Conclusion:Completing a half Ironman triathlon depends on a high rate of muscle glycogenolysis, which demonstrates the importance of exogenous carbohydrate intake during the race. In addition, rates of muscle-glycogen resynthesis might be dampened by the eccentric damage resulting from the run portion of the race.

Effects of elevated plasma FFA and insulin on muscle glycogen usage during exercise

1977 ◽  
Vol 43 (4) ◽  
pp. 695-699 ◽  
Author(s):  
D. L. Costill ◽  
E. Coyle ◽  
G. Dalsky ◽  
W. Evans ◽  
W. Fink ◽  
...  
Keyword(s):  
Muscle Glycogen ◽  
Plasma Insulin ◽  
Control Experiment ◽  
Muscular Activity ◽  
Fold Increase ◽  
Elevated Plasma ◽  
Glycogen Depletion ◽  
Total Carbohydrate ◽  
Plasma Ffa ◽  
Glycogen Utilization

Seven men were studied during 30 min of treadmill exercise (approximately 70% VO2 max) to determine the effects of increased availability of plasma free fatty acids (FFA) and elevated plasma insulin on the utilization of muscle glycogen. This elevation of plasma FFA (1.01 mmol/1) with heparin (2,000 units) decreased the rate of muscle glycogen depletion by 40% as compared to the control experiment (FFA = 0.21 mmol/1). The ingestion of 75 g of glucose 45 min before exercise produced a 3.3-fold increase in plasma insulin and a 38% rise in plasma glucose at 0 min of exercise. Subsequent exercise increased muscle glycogen utilization and total carbohydrate (CHO) oxidation 17 and 13%, respectively, when compared to the control trial. This elevation of plasma insulin produced hypoglycemia (less than 3.5 mmol/1) in most subjects throughout the exercise. These data illustrate the regulatory influence of both plasma insulin and FFA on the rate of CHO usage during prolonged severe muscular activity.

Shivering in the cold: from mechanisms of fuel selection to survival

2006 ◽  
Vol 100 (5) ◽  
pp. 1702-1708 ◽  
Author(s):  
François Haman
Keyword(s):  
Future Research ◽  
Selection Mechanism ◽  
Glycogen Depletion ◽  
Human Survival ◽  
Fuel Selection ◽  
New Information ◽  
Fundamental Research ◽  
Specific Muscle ◽  
Fuel Mixtures ◽  
Shivering Thermogenesis

In cold-exposed adult humans, significant or lethal decreases in body temperature are delayed by reducing heat loss via peripheral vasoconstriction and by increasing rates of heat production via shivering thermogenesis. This brief review focuses on the mechanisms of fuel selection responsible for sustaining long-term shivering thermogenesis. It provides evidence to explain large discrepancies in fuel selection measurements among shivering studies, and it proposes links between choices in fuel selection mechanism and human survival in the cold. Over the last decades, a number of studies have quantified the contributions of carbohydrate (CHO) and lipid to total heat generation. However, the exact contributions of these fuels still remain unclear because of large differences in fuel selection measurements even at the same metabolic rate. Recent advances on the mechanisms of fuel selection during shivering provide some plausible explanations for these discrepancies between shivering studies. This new evidence indicates that muscles can sustain shivering over several hours using a variety of fuel mixtures achieved by modifying diet (changing the size of CHO reserves) or by changing muscle fiber recruitment (increasing or decreasing the recruitment of type II fibers). From a practical perspective, how does the choice of fuel selection mechanism affect human survival in the cold? Based on a glycogen-depletion model, estimates of shivering endurance show that, whereas the oxidation of widely different fuel mixtures does not improve survival time, the selective recruitment of fuel-specific muscle fibers provides a substantial advantage for cold survival. By combining fundamental research on fuel metabolism and applied strategies to improve shivering endurance, future research in this area promises to yield important new information on what limits human survival in the cold.

Effect of cold exposure on fuel utilization in humans: plasma glucose, muscle glycogen, and lipids

2002 ◽  
Vol 93 (1) ◽  
pp. 77-84 ◽  
Author(s):  
François Haman ◽  
François Péronnet ◽  
Glen P. Kenny ◽  
Denis Massicotte ◽  
Carole Lavoie ◽  
...  
Keyword(s):  
Heat Production ◽  
Cold Exposure ◽  
Plasma Glucose ◽  
Muscle Glycogen ◽  
Glucose Oxidation ◽  
Future Research ◽  
Oxidation Rates ◽  
Low Intensity ◽  
Glucose Ingestion ◽  
Shivering Thermogenesis

The relative roles of circulatory glucose, muscle glycogen, and lipids in shivering thermogenesis are unclear. Using a combination of indirect calorimetry and stable isotope methodology ([U-13C]glucose ingestion), we have quantified the oxidation rates of these substrates in men acutely exposed to cold for 2 h (liquid conditioned suit perfused with 10°C water). Cold exposure stimulated heat production by 2.6-fold and increased the oxidation of plasma glucose from 39.4 ± 2.4 to 93.9 ± 5.5 mg/min (+138%), of muscle glycogen from 126.6 ± 7.8 to 264.2 ± 36.9 mg glucosyl units/min (+109%), and of lipids from 46.9 ± 3.2 to 176.5 ± 17.3 mg/min (+376%). Despite the observed increase in plasma glucose oxidation, this fuel only supplied 10% of the energy for heat generation. The major source of carbohydrate was muscle glycogen (75% of all glucose oxidized), and lipids produced as much heat as all other fuels combined. During prolonged, low-intensity shivering, we conclude that total heat production is unequally shared among lipids (50%), muscle glycogen (30%), plasma glucose (10%), and proteins (10%). Therefore, future research should focus on lipids and muscle glycogen that provide most of the energy for heat production.

scholarly journals Mechanisms of Whole-Body Glycogen Deposition after Oral Glucose in Normal Subjects. Influence of the Nutritional Status1

1998 ◽  
Vol 83 (8) ◽  
pp. 2810-2816
Author(s):  
F. Féry ◽  
L. Plat ◽  
E. O. Balasse
Keyword(s):  
Glucose Oxidation ◽  
Normal Subjects ◽  
Whole Body ◽  
Minor Role ◽  
Oral Glucose ◽  
Glycogen Depletion ◽  
Total Carbohydrate ◽  
Glucose Ingestion ◽  
Glycogen Deposition ◽  
A Minor

abstract It is known that prior fasting enhances whole-body glycogen retention after glucose ingestion. To identify the involved mechanisms, 33 normal volunteers underwent a total fast, varying between 14 h and 4 days, and ingested thereafter 75 g glucose labeled with[ 14C]-glucose. Measurements of oral glucose oxidation (expired 14CO2, corrected for incomplete recovery) and total carbohydrate (CHO) oxidation (indirect calorimetry) were performed over the following 5 h. These data allowed us to calculate oral glucose storage (uptake − oxidation), glycogen oxidation (CHO oxidation − oral glucose oxidation), and net CHO balance (oral glucose uptake − CHO oxidation). As compared with an overnight fast, prolonged fasting (4 days) inhibited the uptake (64.8 vs. 70.3 g/5 h; P < 0.01) and the oxidation (10.9 vs. 20.0 g/5h; P< 0.001) of oral glucose and stimulated slightly its conversion to glycogen (53.9 vs. 50.3 g/5 h; P < 0.05). The latter effect played only a minor role in the marked increase in net CHO balance (52.3 vs. 25.2 g/5 h; P < 0.001), which was almost entirely related to a decrease in glycogen oxidation (1.6 vs. 25.1 g/5 h; P < 0.001). Considering the whole series of data, including intermediate durations of fast, it was observed that the modifications in postprandial CHO metabolism, induced by fasting, correlated strongly with basal CHO oxidation, suggesting that the degree of initial glycogen depletion is a major determinant of glycogen oxidation and net CHO storage. Thus, prior fasting stimulates postprandial glycogen retention, mainly through an inhibition of the glycogen turnover that exists in overnight-fasted subjects, during the absorptive period.

scholarly journals Ingestion of glucose or sucrose prevents liver but not muscle glycogen depletion during prolonged endurance-type exercise in trained cyclists

2015 ◽  
Vol 309 (12) ◽  
pp. E1032-E1039 ◽  
Author(s):  
Javier T. Gonzalez ◽  
Cas J. Fuchs ◽  
Fiona E. Smith ◽  
Pete E. Thelwall ◽  
Roy Taylor ◽  
...  
Keyword(s):  
Muscle Glycogen ◽  
Liver Glycogen ◽  
Whole Body ◽  
Peak Power Output ◽  
Resonance Spectroscopy ◽  
Glycogen Depletion ◽  
Carbohydrate Utilization ◽  
Glucose Ingestion ◽  
Before And After ◽  
Effect Of Glucose

The purpose of this study was to define the effect of glucose ingestion compared with sucrose ingestion on liver and muscle glycogen depletion during prolonged endurance-type exercise. Fourteen cyclists completed two 3-h bouts of cycling at 50% of peak power output while ingesting either glucose or sucrose at a rate of 1.7 g/min (102 g/h). Four cyclists performed an additional third test for reference in which only water was consumed. We employed 13C magnetic resonance spectroscopy to determine liver and muscle glycogen concentrations before and after exercise. Expired breath was sampled during exercise to estimate whole body substrate use. After glucose and sucrose ingestion, liver glycogen levels did not show a significant decline after exercise (from 325 ± 168 to 345 ± 205 and 321 ± 177 to 348 ± 170 mmol/l, respectively; P > 0.05), with no differences between treatments. Muscle glycogen concentrations declined (from 101 ± 49 to 60 ± 34 and 114 ± 48 to 67 ± 34 mmol/l, respectively; P < 0.05), with no differences between treatments. Whole body carbohydrate utilization was greater with sucrose (2.03 ± 0.43 g/min) vs. glucose (1.66 ± 0.36 g/min; P < 0.05) ingestion. Both liver (from 454 ± 33 to 283 ± 82 mmol/l; P < 0.05) and muscle (from 111 ± 46 to 67 ± 31 mmol/l; P < 0.01) glycogen concentrations declined during exercise when only water was ingested. Both glucose and sucrose ingestion prevent liver glycogen depletion during prolonged endurance-type exercise. Sucrose ingestion does not preserve liver glycogen concentrations more than glucose ingestion. However, sucrose ingestion does increase whole body carbohydrate utilization compared with glucose ingestion. This trial was registered at https://www.clinicaltrials.gov as NCT02110836.

scholarly journals Brain Metabolic Correlates of Persistent Olfactory Dysfunction after SARS-Cov2 Infection

Biomedicines ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 287
Author(s):  
Maria Isabella Donegani ◽  
Alberto Miceli ◽  
Matteo Pardini ◽  
Matteo Bauckneht ◽  
Silvia Chiola ◽  
...  
Keyword(s):  
Fdg Pet ◽  
Structural Connectivity ◽  
Statistical Parametric Mapping ◽  
Brain Regions ◽  
Olfactory Dysfunction ◽  
Whole Body ◽  
Mapping Software ◽  
18F Fdg ◽  
Left Insula

We aimed to evaluate the brain hypometabolic signature of persistent isolated olfactory dysfunction after SARS-CoV-2 infection. Twenty-two patients underwent whole-body [18F]-FDG PET, including a dedicated brain acquisition at our institution between May and December 2020 following their recovery after SARS-Cov2 infection. Fourteen of these patients presented isolated persistent hyposmia (smell diskettes olfaction test was used). A voxel-wise analysis (using Statistical Parametric Mapping software version 8 (SPM8)) was performed to identify brain regions of relative hypometabolism in patients with hyposmia with respect to controls. Structural connectivity of these regions was assessed (BCB toolkit). Relative hypometabolism was demonstrated in bilateral parahippocampal and fusiform gyri and in left insula in patients with respect to controls. Structural connectivity maps highlighted the involvement of bilateral longitudinal fasciculi. This study provides evidence of cortical hypometabolism in patients with isolated persistent hyposmia after SARS-Cov2 infection. [18F]-FDG PET may play a role in the identification of long-term brain functional sequelae of COVID-19.

scholarly journals Bone mineral density and explanatory factors in children and adults with juvenile dermatomyositis at long term follow-up; a cross sectional study

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Henriette Schermacher Marstein ◽  
Kristin Godang ◽  
Berit Flatø ◽  
Ivar Sjaastad ◽  
Jens Bollerslev ◽  
...  
Keyword(s):  
Bone Turnover ◽  
Inflammatory Markers ◽  
Juvenile Dermatomyositis ◽  
Inflammatory Myopathy ◽  
Disease Onset ◽  
Whole Body ◽  
Mineral Density ◽  
Z Scores

Abstract Background Juvenile dermatomyositis (JDM) is the most common idiopathic inflammatory myopathy in children and adolescents. Both the disease and its treatment with glucocorticoids may negatively impact bone formation. In this study we compare BMD in patients (children/adolescence and adults) with long-standing JDM with matched controls; and in patients, explore how general/disease characteristics and bone turnover markers are associated with BMD. Methods JDM patients (n = 59) were examined median 16.8y (range 6.6–27.0y) after disease onset and compared with 59 age/sex-matched controls. Dual-energy X-ray absorptiometry (DXA) was used to measure BMD of the whole body and lumbar spine (spine) in all participants, and of ultra-distal radius, forearm and total hip in participants ≥20y only. Markers of bone turnover were analysed, and associations with outcomes explored. Results Reduced BMD Z-scores (<−1SD) were found in 19 and 29% of patients and 7 and 9% of controls in whole body and spine, respectively (p-values < 0.05). BMD and BMD Z-scores for whole body and spine were lower in all patients and for < 20y compared with their respective controls. In participants ≥20y, only BMD and BMD Z-score of forearm were lower in the patients versus controls. In patients, BMD Z-scores for whole body and/or spine were found to correlate negatively with prednisolone use at follow-up (yes/no) (age < 20y), inflammatory markers (age ≥ 20y) and levels of interferon gamma-induced protein 10 (IP-10) (both age groups). In all patients, prednisolone use at follow-up (yes/no) and age ≥ 20y were independent correlates of lower BMD Z-scores for whole body and spine, respectively. Conclusion In long-term JDM, children have more impairment of BMD than adults in spine and whole-body. Associations with BMD were found for both prednisolone and inflammatory markers, and a novel association was discovered with the biomarker of JDM activity, IP-10.

scholarly journals Effects of Nutrient Intake Timing on Post-Exercise Glycogen Accumulation and its Related Signaling Pathways in Mouse Skeletal Muscle

Nutrients ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2555 ◽  
Author(s):  
Takahashi ◽  
Matsunaga ◽  
Banjo ◽  
Takahashi ◽  
Sato ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Glycogen ◽  
Nutrient Intake ◽  
Matched Control ◽  
Control Group ◽  
Glycogen Depletion ◽  
Post Exercise ◽  
Glycogen Accumulation ◽  
Matched Control Group ◽  
Significant Difference

We investigated the effects of nutrient intake timing on glycogen accumulation and its related signals in skeletal muscle after an exercise that did not induce large glycogen depletion. Male ICR mice ran on a treadmill at 25 m/min for 60 min under a fed condition. Mice were orally administered a solution containing 1.2 mg/g carbohydrate and 0.4 mg/g protein or water either immediately (early nutrient, EN) or 180 min (late nutrient, LN) after the exercise. Tissues were harvested at 30 min after the oral administration. No significant difference in blood glucose or plasma insulin concentrations was found between the EN and LN groups. The plantaris muscle glycogen concentration was significantly (p < 0.05) higher in the EN group—but not in the LN group—compared to the respective time-matched control group. Akt Ser473 phosphorylation was significantly higher in the EN group than in the time-matched control group (p < 0.01), while LN had no effect. Positive main effects of time were found for the phosphorylations in Akt substrate of 160 kDa (AS160) Thr642 (p < 0.05), 5'-AMP-activated protein kinase (AMPK) Thr172 (p < 0.01), and acetyl-CoA carboxylase Ser79 (p < 0.01); however, no effect of nutrient intake was found for these. We showed that delayed nutrient intake could not increase muscle glycogen after endurance exercise which did not induce large glycogen depletion. The results also suggest that post-exercise muscle glycogen accumulation after nutrient intake might be partly influenced by Akt activation. Meanwhile, increased AS160 and AMPK activation by post-exercise fasting might not lead to glycogen accumulation.

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