Liver glycogen metabolism during and after prolonged endurance-type exercise:hepatic glycogen and endurance exercise

Carbohydrate and fat are the main substrates utilized during prolonged endurance-type exercise. The relative contribution of each is determined primarily by the intensity and duration of exercise, along with individual training and nutritional status. During moderate- to high-intensity exercise, carbohydrate represents the main substrate source. Because endogenous carbohydrate stores ( primarily in liver and muscle ) are relatively small, endurance-type exercise performance/capacity is often limited by endogenous carbohydrate availability. Much exercise metabolism research to date has focused on muscle glycogen utilization, with little attention paid to the contribution of liver glycogen. 13C magnetic resonance spectroscopy permits direct, noninvasive measurements of liver glycogen content and has increased understanding of the relevance of liver glycogen during exercise. In contrast to muscle, endurance-trained athletes do not exhibit elevated basal liver glycogen concentrations. However, there is evidence that liver glycogenolysis may be lower in endurance-trained athletes compared with untrained controls during moderate- to high-intensity exercise. Therefore, liver glycogen sparing in an endurance-trained state may account partly for training-induced performance/capacity adaptations during prolonged ( > 90 min ) exercise. Ingestion of carbohydrate at a relatively high rate ( > 1.5 g/min ) can prevent liver glycogen depletion during moderate-intensity exercise independent of the type of carbohydrate ( e.g., glucose vs. sucrose ) ingested. To minimize gastrointestinal discomfort, it is recommended to ingest specific combinations or types of carbohydrates ( glucose plus fructose and/or sucrose ). By coingesting glucose with either galactose or fructose, postexercise liver glycogen repletion rates can be doubled. There are currently no guidelines for carbohydrate ingestion to maximize liver glycogen repletion

Glucose Plus Fructose Ingestion for Post‐Exercise Recovery—Greater than the Sum of Its Parts?

Abstract: Carbohydrate availability in the form of muscle and liver glycogen is an important determinant of performance during prolonged bouts of moderate- to high-intensity exercise. Therefore, when effective endurance performance is an objective on multiple occasions within a 24-h period, the restoration of endogenous glycogen stores is the principal factor determining recovery. This review considers the role of glucose–fructose co-ingestion on liver and muscle glycogen repletion following prolonged exercise. Glucose and fructose are primarily absorbed by different intestinal transport proteins; by combining the ingestion of glucose with fructose, both transport pathways are utilised, which increases the total capacity for carbohydrate absorption. Moreover, the addition of glucose to fructose ingestion facilitates intestinal fructose absorption via a currently unidentified mechanism. The co-ingestion of glucose and fructose therefore provides faster rates of carbohydrate absorption than the sum of glucose and fructose absorption rates alone. Similar metabolic effects can be achieved via the ingestion of sucrose (a disaccharide of glucose and fructose) because intestinal absorption is unlikely to be limited by sucrose hydrolysis. Carbohydrate ingestion at a rate of ≥ 1.2 g carbohydrate per kg body mass per hour appears to maximise post-exercise muscle glycogen repletion rates. Providing these carbohydrates in the form of glucose–fructose (sucrose) mixtures does not further enhance muscle glycogen repletion rates over glucose (polymer) ingestion alone. In contrast, liver glycogen repletion rates are approximately doubled with ingestion of glucose–fructose (sucrose) mixtures over isocaloric ingestion of glucose(polymers) alone. Furthermore, glucose plus fructose (sucrose) ingestion alleviates gastro intestinal distress when the ingestion rate approaches or exceeds the capacity for intestinal glucose absorption(~1.2 g/min). Accordingly, when rapid recovery of endogenous glycogen stores is a priority, ingesting glucose–fructose mixtures (or sucrose) at a rate of ≥ 1.2 g·kg body mass−1·h−1can enhance glycogen repletion rates whilst also minimising gastrointestinal distress

Hot-water immersion does not increase postprandial muscle protein synthesis rates during recovery from resistance-type exercise in healthy, young males

The purpose of this study was to assess the impact of postexercise hot-water immersion on postprandial myofibrillar protein synthesis rates during recovery from a single bout of resistance-type exercise in healthy, young men. Twelve healthy, adult men (age: 23 ± 1 y) performed a single bout of resistance-type exercise followed by 20 min of water immersion of both legs. One leg was immersed in hot water [46°C: hot-water immersion (HWI)], while the other leg was immersed in thermoneutral water (30°C: CON). After water immersion, a beverage was ingested containing 20 g intrinsically L-[1-13C]-phenylalanine and L-[1-13C]-leucine labeled milk protein with 45 g of carbohydrates. In addition, primed continuous L-[ring-2H5]-phenylalanine and L-[1-13C]-leucine infusions were applied, with frequent collection of blood and muscle samples to assess myofibrillar protein synthesis rates in vivo over a 5-h recovery period. Muscle temperature immediately after water immersion was higher in the HWI compared with the CON leg (37.5 ± 0.1 vs. 35.2 ± 0.2°C; P < 0.001). Incorporation of dietary protein-derived L-[1-13C]-phenylalanine into myofibrillar protein did not differ between the HWI and CON leg during the 5-h recovery period (0.025 ± 0.003 vs. 0.024 ± 0.002 MPE; P = 0.953). Postexercise myofibrillar protein synthesis rates did not differ between the HWI and CON leg based upon L-[1-13C]-leucine (0.050 ± 0.005 vs. 0.049 ± 0.002%/h; P = 0.815) and L-[ring-2H5]-phenylalanine (0.048 ± 0.002 vs. 0.047 ± 0.003%/h; P = 0.877), respectively. Hot-water immersion during recovery from resistance-type exercise does not increase the postprandial rise in myofibrillar protein synthesis rates. In addition, postexercise hot-water immersion does not increase the capacity of the muscle to incorporate dietary protein-derived amino acids in muscle tissue protein during subsequent recovery

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

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 C-13 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

Sucrose ingestion after exhaustive exercise accelerates liver, but not muscle glycogen repletion when compared to glucose ingestion in trained athletes

The purpose of this study was to assess the effects of sucrose vs. glucose ingestion on postexercise liver and muscle glycogen repletion. Fifteen well-trained male cyclists completed two test days. Each test day started with glycogen-depleting exercise, followed by 5 h of recovery, during which subjects ingested 1.5 g·kg−1·h−1 sucrose or glucose. Blood was sampled frequently and 13C magnetic resonance spectroscopy and imaging were employed 0, 120, and 300 min postexercise to determine liver and muscle glycogen concentrations and liver volume. Results were as follows: Postexercise muscle glycogen concentrations increased significantly from 85 ± 27 (SD) vs. 86 ± 35 mmol/l to 140 ± 23 vs. 136 ± 26 mmol/l following sucrose and glucose ingestion, respectively (no differences between treatments: P = 0.673). Postexercise liver glycogen concentrations increased significantly from 183 ± 47 vs. 167 ± 65 mmol/l to 280 ± 72 vs. 234 ± 81 mmol/l following sucrose and glucose ingestion, respectively (time × treatment, P = 0.051). Liver volume increased significantly over the 300-min period after sucrose ingestion only (time × treatment, P = 0.001). As a result, total liver glycogen content increased during postexercise recovery to a greater extent in the sucrose treatment (from 53.6 ± 16.2 to 86.8 ± 29.0 g) compared with the glucose treatment (49.3 ± 25.5 to 65.7 ± 27.1 g; time × treatment, P < 0.001), equating to a 3.4 g/h (95% confidence interval: 1.6-5.1 g/h) greater repletion rate with sucrose vs. glucose ingestion. In conclusion, sucrose ingestion (1.5 g·kg−1·h−1) further accelerates postexercise liver, but not muscle glycogen repletion compared with glucose ingestion in trained athletes

Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

Protein type, protein dose, and age modulate dietary protein digestion and phenylalanine absorption kinetics and plasma phenylalanine availability in humans

This is the final version. Available from the publisher via the DOI in this record.BACKGROUND: Dietary protein ingestion stimulates muscle protein synthesis by providing amino acids to the muscle. The magnitude and duration of the postprandial increase in muscle protein synthesis rates are largely determined by dietary protein digestion and amino acid absorption kinetics. OBJECTIVE: We assessed the impact of protein type, protein dose, and age on dietary protein digestion and amino acid absorption kinetics in vivo in humans. METHODS: We included data from 18 randomized controlled trials with a total of 602 participants [age: 53 ± 23 y; BMI (kg/m2): 24.8 ± 3.3] who consumed various quantities of intrinsically l-[1-13C]-phenylalanine-labeled whey (n = 137), casein (n = 393), or milk (n = 72) protein and received intravenous infusions of l-[ring-2H5]-phenylalanine, which allowed us to assess protein digestion and phenylalanine absorption kinetics and the postprandial release of dietary protein-derived phenylalanine into the circulation. The effect of aging on these processes was assessed in a subset of 82 young (aged 22 ± 3 y) and 83 older (aged 71 ± 5 y) individuals. RESULTS: A total of 50% ± 14% of dietary protein-derived phenylalanine appeared in the circulation over a 5-h postprandial period. Casein ingestion resulted in a smaller (45% ± 11%), whey protein ingestion in an intermediate (57% ± 10%), and milk protein ingestion in a greater (65% ± 13%) fraction of dietary protein-derived phenylalanine appearing in the circulation (P < 0.001). The postprandial availability of dietary protein-derived phenylalanine in the circulation increased with the ingestion of greater protein doses (P < 0.05). Protein digestion and phenylalanine absorption kinetics were attenuated in older when compared with young individuals, with 45% ± 10% vs. 51% ± 14% of dietary protein-derived phenylalanine appearing in the circulation, respectively (P = 0.001). CONCLUSIONS: Protein type, protein dose, and age modulate dietary protein digestion and amino acid absorption kinetics and subsequent postprandial plasma amino acid availability in vivo in humans. These trials were registered at clinicaltrials.gov as NCT00557388, NCT00936039, NCT00991523, NCT01317511, NCT01473576, NCT01576848, NCT01578590, NCT01615276, NCT01680146, NCT01820975, NCT01986842, and NCT02596542, and at http://www.trialregister.nl as NTR3638, NTR3885, NTR4060, NTR4429, and NTR4492

Measurement of the W±Z boson pair-production cross section in pp collisions at √s=13TeV with the ATLAS detector

published_or_final_versio

Measurement of W+W− production in association with one jet in proton–proton collisions at sqrt(s) = 8TeV with the ATLAS detector

The production of W boson pairs in association with one jet in pp collisions at View the MathML sources=8 TeV is studied using data corresponding to an integrated luminosity of 20.3 fb−1 collected by the ATLAS detector during 2012 at the CERN Large Hadron Collider. The cross section is measured in a fiducial phase-space region defined by the presence of exactly one electron and one muon, missing transverse momentum and exactly one jet with a transverse momentum above 25 GeV and a pseudorapidity of |η|<4.5|η|<4.5. The leptons are required to have opposite electric charge and to pass transverse momentum and pseudorapidity requirements. The fiducial cross section is found to be View the MathML sourceσWWfid,1-jet=136±6(stat)±14(syst)±3(lumi) fb. In combination with a previous measurement restricted to leptonic final states with no associated jets, the fiducial cross section of WW production with zero or one jet is measured to be View the MathML sourceσWWfid,≤1-jet=511±9(stat)±26(syst)±10(lumi) fb. The ratio of fiducial cross sections in final states with one and zero jets is determined to be 0.36±0.050.36±0.05. Finally, a total cross section extrapolated from the fiducial measurement of WW production with zero or one associated jet is reported. The measurements are compared to theoretical predictions and found in good agreement

Measurement of the cross section for inclusive isolated-photon production in pp collisions at √s=13TeV using the ATLAS detector

Inclusive isolated-photon production in pp collisions at a centre-of-mass energy of 13TeVis studied with the ATLAS detector at the LHC using a data set with an integrated luminosity of 3.2fb−1. The cross section is measured as a function of the photon transverse energy above 125GeVin different regions of photon pseudorapidity. Next-to-leading-order perturbative QCD and Monte Carlo event-generator predictions are compared to the cross-section measurements and provide an adequate description of the data