Muscle Glycogen Content Research Articles

Consequences of the modulation of gestational resistance training intensity for placental cell composition and nutrient transporter expression.

Resistance training during pregnancy provides benefits for the mother and fetus, but little is known about the effects of resistance training on placental structure and function or the repercussions of modifying resistance training intensity on the mother-fetus-placenta triad. Female Wistar rats were submitted to resistance training involving a ladder climb (80% of maximum load carried (MLC), 5-day/week for 3-weeks) before pregnancy. After confirmation of mating, the rats were randomly divided into three groups, according to resistance training intensity during pregnancy: constant-intensity training (CIT, trained at 80% of MLC through gestation), decreasing-intensity training (DIT, 80% of MLC during first and second weeks of gestation and 50% of MLC in the third week), and undulating-intensity training (UIT, 50% of MLC in the first and third weeks, and 80% of MLC in the second week). A control group did not undergo any training. Samples were collected on gestational day 20. Resistance training had no impact on maternal body weight, muscle glycogen content, adipocyte morphology, number of fetuses, number of absorptions, placental area, or fetal growth parameters. The CIT group presented lower maternal serum glucose. The UIT group presented increased presence of fetal capillaries in the labyrinth zone and increased Glut1, Glut3, and Snat1 expression in the placenta. Snat2 expression was upregulated in all resistance training groups and higher levels of Mtor expression were found in the DIT group. Il1b expression increased in the CIT group, and higher levels of Il10 expression were found in the DIT and UIT groups. Resistance training was safe for pregnant rats. Its influence on glucose and amino acid transport was not dependent on changes in Mtor expression and did not impact fetal growth.

Effect of Food Deprivation on Plasma Cortisol, Carbohydrate Metabolism, and Histomorphology in Clarias batrachus.

The nutritional status of fish is essential for its health, experimental studies, and aquaculture practices. The current study investigated the impact of food deprivation on biochemical parameters, histology of skin, gill, and kidney tissues, and ultrastructure of gills in Clarias batrachus. Fish were subjected to food deprivation for 2, 7, and 15 days resulting in (a) significant increase in plasma cortisol levels, (b) no significant changes in plasma osmolality and plasma glucose content, and (c) significant decrease in liver and muscle glycogen contents. A substantial damage was detected in skin, gill, and kidney tissues with histological alterations in a time-dependent manner. Skin tissue displayed melanomacrophage aggregation, excoriated epidermis and dermis. In gill tissue, epithelial lifting, edema, desquamation, deformed secondary lamellae, and lamellar hyperplasia were observed. Kidney tissue exhibited degenerated tubules, melanomacrophage aggregations, and shrunken renal tubule. Scanning electron microscopy revealed that food deprivation-induced marked presence of mucus, chloride cells, and pavement cells with well-defined microridges and microbridges following 2 days, opening of chloride cells was more prominent after 7 days, while more mucus secretion was observed after 15 days. After food deprivation, alterations in biochemical and histological parameters, and ultrastructural changes in target tissues reflect physiological and morphological disturbances in fish. The novelty of this study is that these parameters can be considered as biomarkers of feeding stress in fish and fish health and can provide important insights for better aquaculture practices.

Impact of stocking densities and road transport distances on meat quality and malondialdehyde levels in semitendinosus and infraspinatus muscles of Brahman crossbred heifers in a tropical climate

Transporting cattle in tropical climates substantially impacts oxidative stability and meat quality due to increased stress levels. The objective of this research is to assess the impacts of road transport with two different distances and three stocking densities on meat quality indices and malondialdehyde (MDA) levels in the infraspinatus (IF) and semitendinosus muscles of Brahman crossbred heifers in a tropical climate. Sixty Brahman crossbred heifers were exposed to two different road travel distances: 450 and 850 km. Each travel distance was divided into three different stocking densities: low density of 200 kg/m2, medium density of 400 kg/m2 and high density of 600 kg/m2. The number of animals in each stocking density was kept equal. Following transit, IF and semitendinosus muscle samples were collected and assessed for meat quality characteristics, including colour attributes, pH, muscle glycogen contents, Warner-Bratzler shear force (WBSF), cooking loss and lipid oxidation. The findings showed notable impacts of livestock densities and road transport distances on meat quality parameters and MDA levels in Brahman crossbred heifers’ muscles. Similarly, increased livestock densities resulted in higher levels of MDA and alterations in meat quality measures than lower densities following both distances of road transportation. These findings highlight the significance of optimising livestock density and reducing road transport lengths to maintain the oxidative stability of meat quality in heifers.

Effects of Japanese Diet on Post-Exercise Glycogen Recovery in Mice Skeletal Muscle and Liver

The diet consumed by most Japanese people, which contains high amounts of carbohydrate and low levels of fat compared with the Western-style diet (WD), has been considered an effective diet for promoting glycogen recovery after exercise. However, there is no direct evidence to support this general belief, because no studies have examined the effect of whole, actually cooked Japanese-style diet (JD) on post-exercise glycogen replenishment. In this study, we comparatively examined the effects of a cooked typical JD and WD on glycogen accumulation in mouse skeletal muscle and liver after acute exercise. One-week menus (total 21 meals) of the JD and WD were reproduced based on national nutrition surveys in Japan and the U.S. All the meals were cooked, mixed and then fed to mice after acute 60-min running exercise. After the 4-h recovery period, mice given the JD had significantly higher muscle and liver glycogen concentrations than those fed the isoenergetic WD. Furthermore, even after the 24-h recovery period, the JD-fed mice also had significantly higher muscle glycogen concentration than the isoenergetic WD-fed group. Compared with the mice fed a WD, the JD-fed mice showed significantly higher plasma insulin level during the 4-h but not the 24-h recovery period. These results suggest that both short- and long-term feeding of the JD promote post-exercise muscle glycogen recovery compared to the WD, possibly through an insulin-dependent mechanism and non-insulin-dependent mechanism, respectively.

The role of AMPK activation in metabolic regulation, energy homeostasis and aging: A comprehensive overview

5’ Adenosine monophosphate-activated protein kinase (AMPK) is a metabolic sensor responsible for maintaining homeostasis, regulating metabolic control, monitoring energy status, and balancing energy production with consumption. The most important protein kinases that activate AMPK are liver kinase B1 and calcium-calmodulin-dependent protein kinase. AMPK significantly impacts physical performance by accelerating recovery periods and restoring energy stores through several key mechanisms. It regulates muscle glycogen content, ensuring readily available energy during physical exertion. In addition, a high number of mitochondria enable the utilization of fatty acids as an energy source, thereby improving endurance efforts. Furthermore, rich vascularization in the muscles enhances the delivery of nutrients and oxygen, optimizing performance and speeding up recovery. AMPK is also important for maintaining muscle homeostasis. It decreases insulin resistance, stimulates mitochondrial biogenesis, and exerts an antioxidant effect. As a regulator of energy homeostasis, AMPK plays a key role in linking cellular energy levels with the aging process. It acts as a modulator of cellular senescence and has the potential to extend life expectancy, particularly in the context of caloric restriction. By activating AMPK, caloric restriction (activated with a 30 – 70% reduction in nutrient intake) helps to maintain energy balance in cells, which may slow down aging and support healthier cellular function over time. In conclusion, the involvement of AMPK in metabolic regulation and maintenance makes it an important therapeutic target for the treatment and prevention of several diseases, both age-related and otherwise.

Investigation of Pajanelia longifolia Leaf Extract for Antidiabetic Activity

Diabetes mellitus (DM) is a medical condition characterized by heightened levels of blood sugar, stemming from either inadequate production of insulin or an impaired response to insulin at the cellular level, whether due to a relative or absolute deficiency of the hormone. Traditional herbal remedies have a significant role in the treatment of DM. Pajanelia longifolia, known by the general population as Pajanelia or Tender wild jack has been a component of traditional herbal medicine in India and other Asian countries for the treatment of various ailments. The current research assessed the antidiabetic activity of Pajanelia longifolia leaf extract in streptozotocin (35 mg/kg, oral route) induced diabetic rats. The study utilized an in vivo streptozotocin induced diabetic model and an in vitro rat hemidiaphragm model for assessment of antidiabetic activity. Acute toxicity studies conducted on liposomes of Pajanelia longifolia leaf extract (2000 mg/kg body weight) proved the drug to be non-toxic. The effects of various doses (100, 200 and 400 mg/kg p.o.) of extract were assessed. Glimepiride (2 mg/kg) and insulin (0.25 IU/ml) were used as the standard drugs for in vivo and in vitro studies, respectively. The decrease in blood glucose levels and the elevation of muscle and liver glycogen content in diabetic rats induced by streptozotocin and the increased glucose uptake and glycogen content observed in in vitro rat hemidiaphragm technique proved that Pajanelia longifolia leaf extract has significant antidiabetic activity.

Rice-Fish Farming Improved Antioxidant Defences, Glucose Metabolism, and Muscle Nutrient of Carassius auratus in Sichuan Province.

Rice-fish farming is an ancient and enduring aquaculture model in China. This study aimed to assess the variations in digestive enzymes, antioxidant properties, glucose metabolism, and nutritional content between Carassius auratus reared in paddy fields and ponds. Notably, the levels of amylase and trypsin in C. auratus from rice paddies were considerably higher compared to those from ponds. Additionally, the hepatic catalase (CAT) activity in fish from paddy (2.45 ± 0.16 U/mg) exceeded that of their pond counterparts (2.27 ± 0.25 U/mg). Regarding glucose metabolism, the activities of key enzymes such as Na+/K+-ATPase (NKA) (paddy: 82.45 ± 6.11 U/g; pond: 78.53 ± 7.18 U/g), hexokinase (HK) (paddy: 9.55 ± 0.58 U/g; pond: 8.83 ± 0.72 U/g), glucokinase (GK) (paddy: 4.09 ± 0.21 IU/g; pond: 3.44 ± 0.33 IU/g), glucose-6-phosphatase (G6Pase) (paddy: 85.71 ± 4.49 IU/g; pond: 79.12 ± 9.34 IU/g), and glucose-6-phosphate dehydrogenase (G6PDH) (paddy: 47.23 ± 3.22 U/g; pond: 42.31 ± 4.93 U/g) were significantly elevated in rice paddy-cultured fish compared to those in ponds. Conversely, phosphor-pyruvate kinase (PK) (paddy: 418.15 ± 31.89 U/g; pond: 570.16 ± 56.06 U/g) activity was markedly reduced in the paddy group. Hepatic glycogen content (paddy: 15.70 ± 0.98 ng/g; pond: 14.91 ± 1.24 ng/g) was also substantially higher in fish from paddy, although no significant differences in muscle glycogen content (paddy: 7.14 ± 0.59 ng/g; pond: 6.70 ± 0.52 ng/g) were observed between the two environments. In terms of nutritional composition, fish raised in paddy exhibited higher crude protein (paddy: 18.46 ± 0.47 g/100 g muscle; pond: 15.57 ± 0.25 g/100 g muscle) and crude ash (paddy: 1.19 ± 0.02 g/100 g muscle; pond: 0.97 ± 0.02 g/100 g muscle) than those in ponds, whereas the crude fat (paddy: 0.87 ± 0.04 g/100 g muscle; pond: 1.66 ± 0.04 g/100 g muscle) was notably lower in paddy fish. Furthermore, fish from rice paddies had a greater total content of monounsaturated fatty acids (MUFA) (paddy: 4.25 ± 0.24 g/100 g muscle; pond: 6.73 ± 0.27 g/100 g muscle), non-essential amino acids (NEAA) (paddy: 9.04 ± 0.3 g/100 g muscle; pond: 7.19 ± 0.21 g/100 g muscle), and delicious amino acids (DAA) (paddy: 7.11 ± 0.2 g/100 g muscle; pond: 5.45 ± 0.19 g/100 g muscle) compared to those from pond cultures. These findings suggest that rice-fish co-culture systems can yield healthier and more environmentally sustainable aquatic products by improving feed digestion and optimizing nutrient metabolism.

ИССЛЕДОВАНИЕ ВЛИЯНИЯ 20-ГИДРОКСИЭКДИЗОНА НА УГЛЕВОДНЫЙ ОБМЕН У ПОРОСЯТ

The effect of 20-hydroxyecdysone on carbohydrate metabolism indices was studied in crossbred piglets (♂ Danish Yorkshire ×♀ Danish Landrace) during the postnatal period of ontogenesis. At the age of 60 days, 2 groups of animals were formed: 1 (control, n=3) and 2 (experiment, n=4), which received compound feed con- taining (g/kg) crude protein 158.7; lysine 7.7; threonine 4.8; methionine 4.6 and metabolizable energy (MJ/kg) 12.7. 20-hydroxyecdysone was introduced into the diet of piglets in the experimental group at the rate of 30 mg/kg of feed. The parameters of carbohydrate metabolism (glucose, pyruvate, lactate concentrations, alpha-amylase and lactate dehydrogenase activity in the blood, glycogen content in the longissimus dorsi muscle and liver) were studied. Statistical processing of the obtained results was performed using the STATISTICA v.12.5 software package. The Mann-Whitney U-test was used to identify differences between animal samples. Differences be- tween groups were considered statistically significant at p≤0.05. The use of 20-hydroxyecdysone in animals dur- ing the postnatal period of ontogenesis for 2 months leads to a decrease in the lactate level in the blood serum (by 17.1%; p<0.05). In animals of the experimental group, compared to the control, an increase in the pyruvate con- tent (by 15.8%; p<0.05), the activity of lactate dehydrogenase and alpha-amylase enzymes in the blood serum was found against the background of a low glucose level in whole blood (by 22.8%; p<0.05). At the same time, in an- imals receiving 20-hydroxyecdysone, compared to the control, an increase in the glycogen level in the liver and longissimus dorsi muscle was found (by 23.0% and 20.7%, respectively; p<0.05). It was concluded that 20-hydroxyecdysone activates the intracellular signaling pathway of phosphatidylinositol-3-kinase and protein kinase B, which leads to an increase in the intensity and direction of carbohydrate metabolism, accompanied by complete oxidation of glucose to pyruvate with a large formation of adenosine triphosphoric acid (ATP) and ef- fective utilization of glucose for glycogen synthesis in the liver and longissimus dorsi muscle.

Arginine–NO pathway modulated energy metabolism in the hepatopancreas and muscle of female Litopenaeus vannamei

Currently, the regulational effect of arginine on the energy metabolism is unknown in broodstock shrimp nutrition. Accordingly, an eight-week feeding trial was conducted to confirm it in female Litopenaeus vannamei. Six diets were formulated to contain graded levels of arginine (2.90 %, 3.58 %, 4.08 %, 4.53 %, 5.04 % and 5.55 %). A total of 540 shrimp (with an initial weight of approximately 14 g) were allocated at random to six treatments, each of which consisted of three tanks with 30 shrimp each. The results showed that with the rise in the level of dietary arginine supplementation, growth performance showed an increasing trend, reaching the highest value in the 5.55 % arginine group. The gene expression of cellular energy sensor AMP-activated protein kinase was up-regulated in muscle and hepatopancreas. Dietary arginine supplementation decreased hemolymph glucose content and hepatopancreas crude lipid content, increased muscle crude lipid content, glycogen content in muscle and hepatopancreas. Dietary arginine increased muscle crude protein content, decreased hepatopancreas crude protein content and activated the target of rapamycin 1 pathway. Above results were further confirmed by gene expression. In addition, shrimp were injected with dsGFP and dsNOS for 48 h and successfully constructed the RNA interference model. The findings showed that the levels of nos, cgmp, ampk (a, b, c), genes involved in glucose metabolism, lipid metabolism and amino acid metabolism were inhibited. In the conclusion, arginine supplementation could promote growth performance through modulating energy metabolism. Arginine–NO pathway modulated energy metabolism in hepatopancreas and muscle to promote tissue glycogen synthesis, muscle protein and lipid deposition in female L. vannamei.

Genetic reduction of skeletal muscle glycogen synthase 1 abundance reveals that the refeeding-induced reversal of elevated insulin-stimulated glucose uptake after exercise is not attributable to achieving a high muscle glycogen concentration.

One exercise session can increase subsequent insulin-stimulated glucose uptake (ISGU) by skeletal muscle. Postexercise refeeding induces reversal of postexercise (PEX)-enhanced ISGU concomitant with attaining high muscle glycogen in rats. To test the relationship between high glycogen and reversal of PEX-ISGU, we injected one epitrochlearis muscle from each rat with adeno-associated virus (AAV) small hairpin RNA (shRNA) that targets glycogen synthase 1 (GS1) and injected contralateral muscles with AAV-shRNA-Scrambled (Scr). Muscles from PEX and sedentary rats were collected at 3-hour PEX (3hPEX) or 6-hour PEX (6hPEX). Rats were either not refed or refed rat-chow during the recovery period. Isolated muscles were incubated with [3H]-3-O-methylglucose, with or without insulin. The results revealed: (1) GS1 abundance was substantially lower for AAV-shRNA-GS1-treated versus AAV-shRNA-Scr-treated muscles; (2) reduced GS1 abundance in refed-rats induced much lower glycogen in AAV-shRNA-GS1-treated versus AAV-shRNA-Scr-treated muscles at 3hPEX or 6hPEX; (3) PEX-ISGU was elevated in not refed-rats at either 3hPEX or 6hPEX versus sedentary controls, regardless of GS1 abundance; (4) PEX-ISGU was not reversed by 3 h of refeeding, regardless of GS1 abundance; (5) despite substantially lower glycogen in AAV-shRNA-GS1-treated versus AAV-shRNA-Scr-treated muscles, elevated PEX-ISGU was eliminated at 6hPEX in both of the paired muscles of refed-rats; and (6) 3hPEX versus sedentary non-refed rats had greater AMP-activated protein kinase-γ3 activity in both paired muscles, but this exercise effect was eliminated in both paired muscles by 3 h of refeeding. In conclusion, the results provided compelling evidence that the reversal of exercise-enhanced ISGU by refeeding was not attributable to the accumulation of high muscle glycogen concentration.

Exercise-induced interactions between skeletal muscle and bone via myokines and osteokine in mice: Role of FNDC5/irisin, IGF-1, and osteocalcin

Skeletal muscle and bone interact to maintain their structure and function. Physical exercise is the most effective and easily applicable strategy to maintain their functions; however, exercise-induced interactions by soluble factors remained elusive. Our study aimed to identify exercise-induced interactions between muscle and bone by examining (1) the effects of myokine on bone and (2) the effects of osteocalcin (OCN) on skeletal muscle. To understand the effects of exercise-induced myokines on bone, we examined the effects of FNDC5 for aerobic exercise and IGF-1 for resistance exercise using a muscle-specific myokine overexpression model. To examine OCN effects on muscle, mice were intraperitoneally administered OCN-neutralizing antibody during long-term exercise. Our result showed that aerobic exercise tended to increase serum HA-tag protein attached to FNDC5 in muscle-specific overexpression groups. In addition, osteoblastic activation was increased only after aerobic exercise with HA/FNDC5 overexpression. Resistance exercise did not alter circulating HA-tag (muscle-derived IGF-1) and bone metabolism after IGF-1/HA overexpression. In the OCN study, aerobic exercise enhanced endurance capacity by restoring muscle glycogen content; however, OCN neutralization returned these to baseline. After resistance exercise, OCN suppression inhibited muscle hypertrophy and strength gains by preventing protein synthesis. Our results suggest that aerobic exercise following FNDC5 muscle overexpression promotes osteoblast activity, which may be partially caused by muscle-derived FNDC5 secretion. In addition, OCN was necessary for muscle adaptation in both aerobic and resistance exercises.

The relation between dietary polysaccharide intake and urinary excretion of tetraglucoside.

The urinary metabolite tetraglucoside (Glc4) is a potential biomarker for hepatic glycogen storage diseases (GSDs). Glc4 is believed to reflect body glycogen content and/or turnover. However, dietary polysaccharide intake may influence Glc4 excretion, potentially limiting the utility of Glc4 as a monitoring biomarker in hepatic GSDs. We aimed to investigate the association of dietary polysaccharide intake with Glc4 excretion. Urinary Glc4 excretion (mmol/mmol creatinine and mmol/24 h) was analyzed using a validated LC-MS/MS method. Data was analyzed from 65 kidney transplant recipients and 58 healthy kidney donors in the TransplantLines cohort study. Spearman's correlation and multivariable linear regression analyses were performed. In the multivariable analysis, dry lean body mass (DLBM), dietary polysaccharide intake, transplantation status, age, sex, and glycated hemoglobin (HbA1c) served as independent variables. Daily variation was examined in 21 healthy individuals of urinary Glc4 excretion in 2-h collections over a 24-h period. Mixed generalized additive models were built to study the association of prior polysaccharide intake with Glc4 excretion. No (univariate) associations were found between polysaccharide intake and Glc4 excretion. However, a significant interaction between DLBM and polysaccharide on 24 h Glc4 excretion was observed in the multivariate analysis. Glc4 excretion throughout the day exhibited no relationship to prior polysaccharide intake. Our findings suggest an indirect effect of polysaccharide intake on Glc4 excretion, potentially due to changes in muscle glycogen content and/or turnover. We have found no evidence that dietary polysaccharides under normal intakes increase urinary Glc4 directly.

Implication of digestive functions and microbiota in the establishment of muscle glycogen differences between divergent lines for ultimate pH

Both the quality of chicken meat and the quality of chicks are influenced by the level of breast muscle glycogen reserves. In order to study the role of digestive metabolism in establishing this muscular phenotype, we compared two divergent chicken lines for the ultimate pH (pHu) of the breast meat, a proxy for glycogen reserves. Males aged 4 weeks had twice the breast muscle glycogen content in the pHu- line (low pHu) than in the pHu + line (high pHu). The increase in glycogen reserves (pHu-) was associated with a higher relative weight of the proventriculus and gizzard, as well as better apparent ileal digestibility of nitrogen and calcium. The diversity of the cecal microbiota was comparable, but three bacterial genera (Lachnospira, Lachnospiraceae UCG-010, Caproiciproducens) varied between the lines. The differences observed could lead to down-regulation of carbon fixation in prokaryotes and of the citrate cycle in the pHu + line. RNA-seq analysis of the jejunum, the major site of nutrient absorption, revealed 149 genes differentially expressed (DE) between the lines, including several genes linked to immunity, hormonal response and circadian rhythms that are less expressed in pHu + animals. Others involved in cell migration and proliferation, and more generally tissue morphogenesis, also differed between the lines. Among the DE genes, several co-localized with Quantitative Trait Loci (QTL) controlling pHu and selection signatures identified in the divergent lines, such as the gene coding for ghrelin, a hormone regulating appetite.

Delaying post-exercise carbohydrate intake impairs next-day exercise capacity but not muscle glycogen or molecular responses.

To investigate how delayed post-exercise carbohydrate intake affects muscle glycogen, metabolic- and mitochondrial-related molecular responses, and subsequent high-intensity interval exercise (HIIE) capacity. In a double-blind cross-over design, nine recreationally active men performed HIIE (10 × 2-min cycling, ~94% W˙peak) in the fed state, on two occasions. During 0-3 h post-HIIE, participants drank either carbohydrates ("Immediate Carbohydrate" [IC], providing 2.4 g/kg) or water ("Delayed Carbohydrate" [DC]); total carbohydrate intake over 24 h post-HIIE was matched (~7 g/kg/d). Skeletal muscle (sampled pre-HIIE, post-HIIE, +3 h, +8 h, +24 h) was analyzed for whole-muscle glycogen and mRNA content, plus signaling proteins in cytoplasmic- and nuclear-enriched fractions. After 24 h, participants repeated the HIIE protocol until failure, to test subsequent HIIE capacity; blood lactate, heart rate, and ratings of perceived effort (RPE) were measured throughout. Muscle glycogen concentrations, and relative changes, were similar between conditions throughout (p > 0.05). Muscle glycogen was reduced from baseline (mean ± SD mmol/kg dm; IC: 409 ± 166; DC: 352 ± 76) at post-HIIE (IC: 253 ± 96; DC: 214 ± 82), +3 h (IC: 276 ± 62; DC: 269 ± 116) and + 8 h (IC: 321 ± 56; DC: 269 ± 116), returning to near-baseline by +24 h. Several genes (PGC-1ɑ, p53) and proteins (p-ACCSer79, p-P38 MAPKThr180/Tyr182) elicited typical exercise-induced changes irrespective of condition. Delaying carbohydrate intake reduced next-day HIIE capacity (5 ± 3 intervals) and increased RPE (~2 ratings), despite similar physiological responses between conditions. Molecular responses to HIIE (performed in the fed state) were not enhanced by delayed post-exercise carbohydrate intake. Our findings support immediate post-exercise refueling if the goal is to maximize next-day HIIE capacity and recovery time is ≤24 h.

Responses to Exercise with Low Carbohydrate Availability on Muscle Glycogen and Cell Signaling: A Systematic Review and Meta-analysis.

The growing interest in how exercise and carbohydrate (CHO) restriction may modify molecular responses that promote endurance adaptations has led to many interesting controversies. We conducted a systematic review and a meta-analysis regarding the effect of low-carbohydrate availability (LOW) pre-, during, or post-exercise, on the mRNA content of commonly measured genes involved in mitochondrial biogenesis (PGC-1α, TFAM mRNA) and metabolism (PDK4, UCP3 and GLUT4 mRNA), and on muscle glycogen levels, compared with a high-CHO (CON) condition. MEDLINE, Scopus, and Web of Science databases were searched following the PRISMA 2020 guidelines (with an end date of November 2023). In total, 19 randomized-controlled studies were considered for inclusion. We evaluated the methodological quality of all studies using the Cochrane Risk of Bias tool for randomized clinical studies. A meta-analysis was performed using a random effects model to calculate the standardized mean difference (SMD), estimated by Hedges' g, and 95% confidence intervals (CIs). The LOW condition was associated with an increased mRNA content of several genes during the early recovery period post-exercise, such as PDK4 (SMD 1.61; 95% CI 0.80-2.42), GLUT4 (SMD 1.38; 95% CI 0.46-2.30), and UCP3 (SMD 2.05; 95% CI 0.40-3.69). However, overall, there was no significant effect on the mRNA content of PGC-1α or TFAM. Finally, CHO restriction and exercise significantly reduced muscle glycogen levels (SMD 3.69; 95% CI 2.82-5.09). A meta-analysis of subgroups from studies with a difference in muscle glycogen concentration of > 200mmolkgdw-1 between the LOW and CON conditions showed an increase in exercise-induced PGC-1α mRNA (SMD 2.08; 95% CI 0.64-3.52; p = 0.005; I2 = 75%) and a greater effect in PDK4 and GLUT4 mRNA. The meta-analysis results show that CHO restriction was associated with an increase in the exercise-induced mRNA content of PDK4, UCP3, and GLUT4, but not the exercise-induced mRNA content of PGC-1ɑ and TFAM. However, when there were substantial differences in glycogen depletion between CON and LOW CHO conditions (> 200mmolkgdw-1), there was a greater effect of CHO restriction on the exercise-induced mRNA content of metabolic genes, and an increase in exercise-induced PGC-1α mRNA.

Exogenous Lactate Treatment Immediately after Exercise Promotes Glycogen Recovery in Type-II Muscle in Mice.

Recent studies suggest that lactate intake has a positive effect on glycogen recovery after exercise. However, it is important to verify the effect of lactate supplementation alone and the timing of glycogen recovery. Therefore, in this study, we aimed to examine the effect of lactate supplementation immediately after exercise on glycogen recovery in mice liver and skeletal muscle at 1, 3, and 5 h after exercise. Mice were randomly divided into the sedentary, exercise-only, lactate, and saline-treated groups. mRNA expression and activation of glycogen synthesis and lactate transport-related factors in the liver and skeletal muscle were assessed using real-time polymerase chain reaction. Skeletal muscle glycogen concentration showed an increasing trend in the lactate group compared with that in the control group at 3 and 5 h after post-supplementation. Additionally, exogenous lactate supplementation significantly increased the expression of core glycogen synthesis enzymes, lactate transporters, and pyruvate dehydrogenase E1 alpha 1 in the skeletal muscles. Conversely, glycogen synthesis, lactate transport, and glycogen oxidation to acetyl-CoA were not significantly affected in the liver by exogenous lactate supplementation. Overall, these results suggest that post-exercise lactate supplement enables glycogen synthesis and recovery in skeletal muscles.

Effects of dietary replacement of fishmeal by defatted Tenebrio molitor meal, Clostridium autoethanogenum protein meal and Chlorella vulgaris meal on the freshness of turbot (Scophthalmus maximus) during chilled storage

The present work evaluated the effects of dietary fishmeal replacement with three non-food protein sources, including defatted Tenebrio molitor meal (TM), Clostridium autoethanogenum protein meal (CAP) and Chlorella vulgaris meal (CV), on the freshness traits of turbot Scophthalmus maximus. TM, CAP, or CV were used to respectively replace 0 %, 15 %, 30 %. 45 %, 60 % and 75 % of dietary fishmeal protein. Turbot (180.5 ± 2.5 g) were fed with eighteen experimental diets for 70 days, and were stored at 4 ℃ for 3 days. TM and CAP linearly increased QIM scores, but no obvious trend between QIM scores and CV dietary level. The TM15 diet decreased the QIM score, indicating better overall freshness compared to the other TM-groups. Chromameter indicated that consumers could not distinguish the color differences among groups (ΔE < 3). The muscle hardness of all groups was significantly reduced after storage (P<0.05), except the fish fed TM15 diet. Moreover, the TM15 group showed lower pH, TVB-N, and TBA levels after storage, whereas higher TM replacement levels (>30 %) resulted in increased pH, TVB-N, and TBA levels compared with the fish fed TM0 diet. But cathepsin B and L activities showed no significant differences across all TM-groups. Among the CAP-groups, no significant differences were noted in pH and TBA levels; however, CAP linearly increased TVB-N levels after storage. CV did not significantly influence the post-storage pH, TVB-N, and TBA levels. The muscle glycogen content showed no significant variance among the groups. In conclusion, a 15 % dietary replacement of fishmeal with TM optimized the freshness of turbot by decelerating muscle softening, lipid oxidation, and the production of volatile nitrogen compounds, whereas higher levels of TM accelerated these processes. CAP replacement level exceeding 15 % enhanced the production of volatile nitrogen compounds. Dietary inclusion of CV did not impact the freshness of turbot during storage.

Systematical Investigation on Anti-Fatigue Function and Underlying Mechanism of High Fischer Ratio Oligopeptides from Antarctic Krill on Exercise-Induced Fatigue in Mice.

High Fischer ratio oligopeptides (HFOs) have a variety of biological activities, but their mechanisms of action for anti-fatigue are less systematically studied at present. This study aimed to systematically evaluate the anti-fatigue efficacy of HFOs from Antarctic krill (HFOs-AK) and explore its mechanism of action through establishing the fatigue model of endurance swimming in mice. Therefore, according to the comparison with the endurance swimming model group, HFOs-AK were able to dose-dependently prolong the endurance swimming time, reduce the levels of the metabolites (lactic acid, blood urea nitrogen, and blood ammonia), increase the content of blood glucose, muscle glycogen, and liver glycogen, reduce lactate dehydrogenase and creatine kinase extravasation, and protect muscle tissue from damage in the endurance swimming mice. HFOs-AK were shown to enhance Na+-K+-ATPase and Ca2+-Mg2+-ATPase activities and increase ATP content in muscle tissue. Meanwhile, HFOs-AK also showed significantly antioxidant ability by increasing the activities of superoxide dismutase and glutathione peroxidase in the liver and decreasing the level of malondialdehyde. Further studies showed that HFOs-AK could regulate the body's energy metabolism and thus exert its anti-fatigue effects by activating the AMPK signaling pathway and up-regulating the expression of p-AMPK and PGC-α proteins. Therefore, HFOs-AK can be used as an auxiliary functional dietary molecules to exert its good anti-fatigue activity and be applied to anti-fatigue functional foods.

The Effects of Water Flow Speed on Swimming Capacity and Energy Metabolism in Adult Amur Grayling (Thymallus grubii)

The present study aimed to explore whether water flow velocity could affect the swimming ability and overall energy metabolism of wild Amur grayling (Thymallus grubii). Swimming performance was assessed by measuring critical swimming speed (Ucrit), burst speed (Uburst), and oxygen consumption rate (MO2) based on the stepped velocity test method. Our results showed that the absolute values of Ucrit and Uburst tended to increase with body length. In contrast, the relative values of Ucrit and Uburst tended to decrease and increase, respectively. MO2 in Amur grayling was elevated with increasing velocity, suggesting relatively high swimming efficiency. We also measured the biochemical indices related to energy metabolism. Lactate dehydrogenase, hexokinase, and pyruvate kinase activities significantly increased (p &lt; 0.05). Hepatic glycogen, glucose, and muscle glycogen contents decreased with the increasing trend of velocity (p &lt; 0.05), the lactic acid contents of the blood and muscles increased significantly with the increase in velocities (p &lt; 0.05), and changes in creatine phosphate content showed no significant difference (p &gt; 0.05). The results not only denote the relationship between body size and swimming speed but also show the effects of water flow velocity on energy metabolism in Amur grayling. The results provide basic data for the construction of fish passage.

Trehalose Improved 20-min Cycling Time-Trial Performance After 100-min Cycling in Amateur Cyclists.

Carbohydrate (CHO) supplementation during endurance exercise can improve performance. However, it is unclear whether low glycemic index (GI) CHO leads to differential ergogenic and metabolic effects compared with a standard high GI CHO. This study investigated the ergogenic and metabolic effects of CHO supplementation with distinct GIs, namely, (a)trehalose (30g/hr), (b)isomaltulose (30g/hr), (c)maltodextrin (60g/hr), and (d)placebo (water). In this double-blind, crossover, counterbalanced, placebo-controlled study, 13 male cyclists cycled a total of 100min at varied exercise intensity (i.e.,10-min stages at 1.5, 2.0, and 2.5W/kg; repeated three times plus two 5-min stages at 1.0W/kg before and after the protocol), followed by a 20-min time trial on four separated occasions. Blood glucose and lactate (every 20min), heart rate, and ratings of perceived exertion were collected throughout, and muscle biopsies were taken before and immediately after exercise. The results showed that trehalose improved time-trial performance compared with placebo (total work done 302 ± 39 vs. 287 ± 48kJ; p = .01), with no other differences between sessions (all p ≥ .07). Throughout the 100-min protocol, blood glucose was higher with maltodextrin compared with the other supplements at all time points (all p < .05). Heart rate, ratings of perceived exertion, muscle glycogen content, blood glucose, and lactate were not different between conditions when considering the 20-min time trial (all p > .05). Trehalose supplementation throughout endurance exercise improved cycling performance and appears to be an appropriate CHO source for exercise tasks up to 2hr. No ergogenic superiority between the different types of CHO was established.