Carbohydrate Oxidation Research Articles

Adult‐Onset Exercise Improves Mitochondria Efficiency of the Heart in Female Offspring Born from Dams Fed a High‐Fat and a High‐Sucrose Diet

A wealth of studies have shown that an adverse intrauterine and perinatal environment is a strong predictor for cardiometabolic diseases in offspring. Conversely, maternal exercise before and during pregnancy has been shown to diminish the risk of offspring developing metabolic disorders later in life. A few promising human and animal studies demonstrated that adult‐onset exercise in offspring can overcome the detrimental effects on offspring health associated with maternal obesity. However, it is unknown whether exercise initiated by adult offspring can mitigate the negative cardiometabolic health induced by maternal obesity. Female CD‐1 mice were fed either a high‐fat, high‐sucrose diet (HFHS) or a refined low‐fat, low‐sucrose diet (LFLS) for eight weeks before pregnancy and gestation, and during lactation. All dams were sedentary throughout the study. At 21 days, female offspring were weaned onto their maternal diet. At 15 weeks, offspring were randomly divided into exercise and sedentary groups which yielded 4 groups: LLS, LLE, HHS, and HHE (first letter denotes maternal diet, second letter offspring diet, and third letter indicates sedentary (S) and exercised group in offspring(E)). For exercise groups, mice had unrestricted exercise wheel access for 10 weeks. Glucose tolerance test (GTT) was performed at 25 weeks and tissues were collected to evaluate cardiac mitochondrial respiratory function at 26 weeks. Maternal diet did not affect body weight (BW) at weaning. Diet did not affect the daily average distance or hours run. BW was significantly higher in the HHS compared to other groups, but exercise did not alter final body weight. This was also true for fat mass. Exercise induced cardiac hypertrophy in mice fed LL, but not in HH mice. Surprisingly, mice in HHE had impaired glucose tolerance compared to other groups. However, no difference was found between LLE and LLS for GTT. In freshly isolated cardiac mitochondria, HHS significantly lowered the coupling efficiency of carbohydrate (pyruvate) and fatty acid (palmitoylcarnitine) oxidation compared to LLS. Exercise training prevented these effects in the HH mice, but had no exercise effect on OXPHOS coupling with either substrate in LL mice. These results demonstrate that adult‐onset exercise can prevent the deleterious effects of maternal obesity on cardiac mitochondrial function in offspring, but may alter glucose handling by mechanisms that merit further investigation.

Progesterone Treatment Attenuates Body Weight Gain, Adiposity and Glycaemic Metabolism Damage in Obese Female Mice

Since the incidence of gestational diabetes is higher in obese women and those treated with progestogens during pregnancy, the aim of this study was to investigate the effect of progesterone (PG) on body composition, glucose metabolism and metabolic parameters in obese female mice. Post‐weaned female C57Bl/J6 were distributed into four groups: normocaloric control (NO‐CO, n=11), high fat and fructose control (HFF‐CO, n=10), normocaloric PG (NO‐PG, n=8) and high fat and fructose PG (HFF‐PG, n=9). The NO‐CO and NO‐PG mice fed a AING93 standard diet and the HFF‐CO and HFF‐PG fed a AIN93G diet added of lard (31%) and fructose (24%) during 10 weeks. In the 7th week, NO‐PG and HFF‐PG received an osmotic pump implant for constant infusion (0,25 mg/kg/d) of PG. All procedures were approved by the Ethics Committee of the School of Arts, Sciences and Humanities of University of Sao Paulo (003/2018). The daily food intake in grams was similar in all groups, but in terms of calories, the intake of the HFF‐CO and HFF‐PG (13.24+0.9 and 13.06+0.72 kcal/animal) groups was higher than NO‐CO and NO‐PG (9.22+0.2 and 9.53+0.53 kcal/animal) groups. The body weight gain was greater the HFF‐CO and HFF‐PG (11.52+0.94 and 9.61+0.85 g) groups compared to NO‐CO and NO‐PG (5.85+0.51 and 5.69+0.5 g) groups. Considering the final body weight of these animals (NO‐CO, 22.14+0.34 g; NO‐PG, 21.89+0.33 g; HFF‐CO, 28.76+0.59 g; HFF‐PG, 26.27+0.67 g) we observed not only the predicted increase in the weight of groups that received the HFF‐CO diet but also a lower increase in HFF‐PG group compared to HFF‐CO group. White adipose tissue fat pads (subcutaneous, SC‐WAT and retroperitoneal, RP‐WAT) increased significantly in the HFF‐CO group compared to NO‐CO and PG groups. In HFF‐PG, both WAT fat pads were greater compared to NO‐PG group, but only the WAT‐RP was greater compared to NO‐CO group. No differences were observed in interscapular brown adipose tissue and pancreas weight. On the other hand, the weight of liver was lower in HFF and HFF‐PG compared to NO‐CO and PG groups. No difference was found in the fasting glycaemia in the animals. From the results of the GTT and area under the curve (AUC) we observed that the HFF (23907+1304 mg/dL/120min) presented significantly higher AUC than NO‐CO and NO‐PG (17327+1042 and 18096+989 mg/dL/120min) groups. In addition, kITT of HFF‐CO (2.86+0.26 %/min) was significantly smaller compared to NO‐CO (4.23+0.56 %/min), NO‐PG (4.07+0.64 %/min) and HFF‐PG (3.89+0.4 %/min). Metabolic parameters measured in the indirect calorimetry during resting such as resting oxygen consumption, energy expenditure, respiratory exchange ratio, and the rates of carbohydrate and lipids oxidation did not differ among groups. In conclusion, the treatment with PG in a concentration that mimics those found in pregnancy attenuated body weight gain, adiposity and glycaemic metabolism damage observed in obese female mice.

Change in Metabolomic Profile Associated with an Average Increase in Plain Water Intake of >+1 L/day, Sustained over 4 Weeks, in Healthy Young Men with Initial Total Water Intake below 2 L/day

Cells adapt to chronic extracellular hypotonicity by altering metabolism, such that cell‐level chronic disease risk factors are reduced. Corresponding effects of sustained whole‐body hydration are hypothesized but remain to be confirmed and translated into population‐level chronic disease prevention.This analysis aimed to 1) describe change in urine and serum metabolomic profiles associated with change in hydration, induced by four weeks of sustained higher intake of drinking water, 2) check if features recognized as key osmolytes in specific tissues changed in urine and/or serum, and 3) identify which metabolic pathways might potentially be impacted by sustained hypotonic hydration.Adapt Study [Stookey JD et al., Physiol Rep 2013;1(5)] data from for 4 healthy, normal weight men (20‐25 years) who transitioned from not meeting to meeting 3 osmolality criteria (urine:<800mmol/kg, serum:<295mmol/kg and saliva:<100mmol/kg) over 4 weeks of >+1L/d intake of drinking water were used for this analysis. Untargeted metabolomic assays were performed by the UC Davis West Coast Metabolomic Center on first‐morning urine collected after overnight food and water restriction and urine (t+60min) and serum (t+90min) collected after a 750 ml bolus of drinking water. Metaboanalyst 5.0 was used to compare Week 1 vs Week 6 metabolomic profiles, using heatmap, OPLS‐DA, fold‐change, and pathway analyses.In heatmap and OPLS‐DA plots, metabolomic profiles appeared more similar in Week 6.Over 350 metabolic features decreased by 2‐fold or more relative to creatinine for at least 3 out of 4 participants in first‐morning and post‐bolus urine. Over 200 features increased by 2‐fold or more relative to creatinine in serum. A wide variety of known compounds changed by 2‐fold or more in at least one specimen type, including alcohols, monosaccharides, disaccharides, sugar acids, polyols, azoline, lactone, nucleosides, phenols, purines, pyridines, pyrimidines, fatty acids, cholesterol, glycerolipids, amino acids, carboxylic acids, phosphate, and urea. Based on hypergeometric test p‐value <0.05 or pathway impact factor >0.2, sustained +1L/d of drinking water was associated with concurrent changes in carbohydrate, protein, lipid, and micronutrient metabolism, a ‘reverse’ Warburg‐like pattern favoring carbohydrate oxidation via the TCA cycle in Week 6.The results warrant further work to leverage cell hydration effects for chronic disease prevention.

Study of Serum Magnesium Level in Type 2 Diabetes Mellitus in Relation to Its Microvascular Complication

Magnesium is an essential element and has a fundamental role in carbohydrate metabolism in general and in the insulin action in particular. Magnesium is a cofactor in both glucose transport mechanism of the cell membranes and for various intracellular enzymes involved in carbohydrate oxidation the concentrations of magnesium in serum of healthy people are remarkably constant, whereas 25-39% of diabetics have low concentrations of serum magnesium. Magnesium depletion has a negative impact on glucose homeostasis and insulin sensitivity in patients with type 2 diabetes, as well as on the evolution of complications such as ischemic heart disease, arterial atherosclerosis, hypercholesterolemia, hyper triglyceridemia, hypertension, retinopathy, neuropathy and nephropathy. Moreover, low serum magnesium is a strong, independent predictor of development of type 2 diabetes. The study is one and half year observational comparative hospital based study conducted in patients attending the Medicine OPD. Randomly chosen 100 Type 2 diabetic patients, and 100 non diabetic age/sex matched controls were included. In this study significant correlation is found between Hypomagnesemia and Diabetic Retinopathy. Diabetes Mellitus Type 2 with Hypomagnesemia is associated with more microvascular complications. Serum Magnesium level also found to be correlated with Lipid profile in Diabetics and significant correlation was also found between Hypomagnesemia and Hypertension. Keywords: Serum Magnesium Level, Type 2 Diabetes Mellitus, Microvascular Complication.

Insulin Sensitivity and Metabolic Flexibility Parallel Plasma TCA Levels in Early Chronotype With Metabolic Syndrome.

People characterized as late chronotype have elevated type 2 diabetes and cardiovascular disease risk compared to early chronotype. It is unclear how chronotype is associated with insulin sensitivity, metabolic flexibility, or plasma TCA cycle intermediates concentration, amino acids (AA), and/or beta-oxidation. This study examined these metabolic associations with chronotype. The Morningness-Eveningness Questionnaire (MEQ) was used to classify adults with metabolic syndrome (ATP III criteria) as either early (n = 15 [13F], MEQ = 64.7 ± 1.4) or late (n = 19 [16F], MEQ = 45.5 ± 1.3) chronotype. Fasting bloods determined hepatic (HOMA-IR) and adipose insulin resistance (Adipose-IR) while a 120-minute euglycemic clamp (40 mU/m2/min, 5 mmoL/L) was performed to test peripheral insulin sensitivity (glucose infusion rate). Carbohydrate (CHOOX) and fat oxidation (FOX), as well as nonoxidative glucose disposal (NOGD), were also estimated (indirect calorimetry). Plasma tricarboxylic acid cycle (TCA) intermediates, AA, and acyl-carnitines were measured along with VO2max and body composition (DXA). There were no statistical differences in age, BMI, fat-free mass, VO2max, or ATP III criteria between groups. Early chronotype, however, had higher peripheral insulin sensitivity (P = 0.009) and lower HOMA-IR (P = 0.02) and Adipose-IR (P = 0.05) compared with late chronotype. Further, early chronotype had higher NOGD (P = 0.008) and greater insulin-stimulated CHOOX (P = 0.02). While fasting lactate (P = 0.01), TCA intermediates (isocitrate, α-ketoglutarate, succinate, fumarate, malate; all P ≤ 0.04) and some AA (proline, isoleucine; P = 0.003-0.05) were lower in early chronotype, other AA (threonine, histidine, arginine; all P ≤ 0.05) and most acyl-carnitines were higher (P ≤ 0.05) compared with late chronotype. Greater insulin sensitivity and metabolic flexibility relates to plasma TCA concentration in early chronotype.

Beyond the Calorie Paradigm: Taking into Account in Practice the Balance of Fat and Carbohydrate Oxidation during Exercise?

Recent literature shows that exercise is not simply a way to generate a calorie deficit as an add-on to restrictive diets but exerts powerful additional biological effects via its impact on mitochondrial function, the release of chemical messengers induced by muscular activity, and its ability to reverse epigenetic alterations. This review aims to summarize the current literature dealing with the hypothesis that some of these effects of exercise unexplained by an energy deficit are related to the balance of substrates used as fuel by the exercising muscle. This balance of substrates can be measured with reliable techniques, which provide information about metabolic disturbances associated with sedentarity and obesity, as well as adaptations of fuel metabolism in trained individuals. The exercise intensity that elicits maximal oxidation of lipids, termed LIPOXmax, FATOXmax, or FATmax, provides a marker of the mitochondrial ability to oxidize fatty acids and predicts how much fat will be oxidized over 45–60 min of low- to moderate-intensity training performed at the corresponding intensity. LIPOXmax is a reproducible parameter that can be modified by many physiological and lifestyle influences (exercise, diet, gender, age, hormones such as catecholamines, and the growth hormone-Insulin-like growth factor I axis). Individuals told to select an exercise intensity to maintain for 45 min or more spontaneously select a level close to this intensity. There is increasing evidence that training targeted at this level is efficient for reducing fat mass, sparing muscle mass, increasing the ability to oxidize lipids during exercise, lowering blood pressure and low-grade inflammation, improving insulin secretion and insulin sensitivity, reducing blood glucose and HbA1c in type 2 diabetes, and decreasing the circulating cholesterol level. Training protocols based on this concept are easy to implement and accept in very sedentary patients and have shown an unexpected efficacy over the long term. They also represent a useful add-on to bariatric surgery in order to maintain and improve its weight-lowering effect. Additional studies are required to confirm and more precisely analyze the determinants of LIPOXmax and the long-term effects of training at this level on body composition, metabolism, and health.

Different Isocaloric Meals and Adiposity Modify Energy Expenditure and Clinical and Metabolomic Biomarkers During Resting and Exercise States in a Randomized Crossover Acute Trial of Normal-Weight and Overweight/Obese Men

BackgroundFew studies have assessed the integrative effects of diet, BMI, and exercise on postprandial changes in energy and circulating metabolic profiles. ObjectivesWe aimed to assess the collective effects of 3 isocaloric meals high in carbohydrate (74.2% energy), fat (64.6% energy), or protein (39.5% energy) on energy expenditure and clinical and metabolomic biomarkers under resting and exercise conditions in normal-weight and overweight/obese men. MethodsThis crossover controlled acute trial included 20 normal-weight (BMI, 18.5 to <24 kg/m2) and 20 overweight/obese (BMI ≥24 kg/m2) men aged 18–45 years. Each of 3 test meals was provided for 2 continuous days: a resting day without exercise, followed by an exercise day with a bicycling exercise of 50% maximal oxygen consumption (postprandial 90–120 minutes). Energy expenditure (exploratory outcome of primary interest) was measured using indirect calorimetry. Fasting and postprandial 2-hour serum clinical and metabolomic biomarkers (secondary interest) were measured. Mixed models were used to examine the effects of meal, time, and/or BMI category. ResultsOn the resting day, no significant between-meal differences were detected for energy expenditure. However, high-carbohydrate and high-fat meals induced the highest postprandial 2-hour increase in glucose (0.34 ± 0.15 mmol/L) and triglyceride (0.95 ± 0.09 mmol/L), respectively, while the high-protein meal reduced glucose (−0.48 ± 0.08 mmol/L) and total cholesterol (−0.01 ± 0.03 mmol/L; all Pmeal values < 0.001). On the exercise day, a high-carbohydrate meal significantly promoted the carbohydrate oxidation rate but suppressed the fat oxidation rate (Pmeal < 0.05), while its postprandial glucose response was attenuated by bicycling (−0.31 ± 0.03 mmol/L; Pexercise < 0.001). We identified 69 metabolites as key features in discriminating between the 3 meals, and overweight/obese men had more varieties of metabolites than normal-weight men. ConclusionsThree isocaloric meals induced unique postprandial changes in clinical and metabolomic biomarkers, while exercise prevented the hyperglycemia induced by a high-carbohydrate meal. Overweight/obese men were more responsive to the meal challenges than normal-weight men. This trial was registered at clinicaltrials.gov as NCT03231618.

Effects of gradient and age on energy expenditure and fat metabolism during aerobic exercise at equal intensity in women.

[Purpose]This study aimed to investigate the effects of gradient and age on energy expenditure and fat metabolism during aerobic exercise at equal intensity in women.[Methods] Thirty women in their twenties (n=15) and fifties (n=15) were enrolled. All subjects performed aerobic exercise on a treadmill for 10 min at 0% and 6% gradient repeatedly to elicit 50%, 60%, and 70% VO2max.[Results]Energy expenditure and fat oxidation were higher during aerobic exercise at 6% of the gradient than at 0%, and there was no significant difference in carbohydrate oxidation in any age group.[Conclusion]Aerobic exercise at a 6% gradient was more favorable for fat oxidation than a 0% gradient in all age groups. In particular, in the case of women in their fifties, walking on a gradient of 6%, which is favorable for increasing fat oxidation, was more effective than walking on flat ground for preventing and reducing obesity. However, to examine the difference in fat oxidation among exercise intensities more accurately, exercise performed for longer than 30 min is required. Follow-up studies are required to investigate the effect of various gradients on physiological and metabolic characteristics when carrying out aerobic exercises for more than 30 min.

Comparison of energy expenditure and substrate oxidation between walking and running in men and women.

[Purpose]The present study compared energy metabolism between walking and running at equivalent speeds during two incremental exercise tests.[Methods]Thirty four university students (18 males, 16 females) were recruited. Each participant completed two trials, consisting of walking (Walk) and running (Run) trials on different days, with 2-3 days apart. Exercise on a treadmill was started from initial stage of 3 min (3.0 k/m in Walk trial, 5.0 km/h in Run trial), and the speed for walking and running was progressively every minute by 0.5 km/h. The changes in metabolic variables, heart rate (HR), and rating of perceived exertion (RPE) during exercise were compared between the trials.[Results]Energy expenditure (EE) increased with speed in each trial. However, the Walk trial had a significantly higher EE than the Run trial at speeds exceeding 92 ± 2 % of the maximal walking speed (MWS, p < 0.01). Similarly, carbohydrate (CHO) oxidation was significantly higher in the Walk trial than in the Run trial at above 92 ± 2 %MWS in males (p < 0.001) and above 93 ± 1 %MWS in females (p < 0.05).[Conclusion]These findings suggest that EE and CHO oxidation during walking increase non-linearly with speed, and walking at a fast speed causes greater metabolic responses than running at the equivalent speed in young participants.

The Effect of Co-Ingestion of Carbohydrate with Milk after Exercise in Healthy Women: Study Considering the Menstrual Cycle.

This study aimed to assess the effects of co-ingestion of carbohydrate with milk (MILK) and isocaloric carbohydrate beverage (CHO) on post-exercise recovery and subsequent exercise capacity, considering the menstrual cycle. This study included 12 women with regular menstrual cycles who completed four test days, which started with glycogen-depleting exercise using a cycle ergometer in the early follicular phase (EF) and late follicular phase (LF), followed by 240 min of recovery from the ingestion of 200 mL of CHO or MILK every 30 min immediately after the exercise (POST0) until 210 min post-exercise. After 240 min, participants performed an exercise capacity test. Blood samples and breathing gas samples were collected before the exercise (PRE), POST0, and 120 (POST120) and 240 min after the end of exercise (POST240) to determine the concentrations of estradiol, progesterone, blood glucose, blood lactate, free fatty acid (FFA), and insulin and the respiratory exchange ratio, fat oxidation, and carbohydrate oxidation. The exercise time at exercise capacity test was not significantly different in terms of menstrual cycle phases and recovery beverages ingested. However, there was a significant positive correlation between the exercise capacity test and area under the curve (AUC) of FFA concentrations from POST0 to POST240 in each group (EF + CHO, p < 0.05; LF + CHO, p < 0.05; EF + MILK, p < 0.01; and LF + MILK, p < 0.05). The AUC of FFA from POST120 to POST240 showed no difference between EF (CHO and MILK) and LF (CHO and MILK). However, the AUC of FFA concentrations from POST120 to POST240 was significantly greater in MILK (EF and LF) than that in CHO (EF and LF) (p < 0.05). In active women, circulating substrates and hormone concentrations during short recovery post-exercise are not affected by the menstrual cycle. However, MILK may affect circulating substrates during recovery and the exercise capacity after recovery.

Abstract P208: The Impact Of Circadian Misalignment On Energy Metabolism And Substrate Oxidation In Adults With Adequate Sleep

Background: Circadian misalignment (CM), the mismatch between timing of behaviors and internal body clock, increases cardiometabolic risk, but the mechanisms are not fully understood. Population studies in night shift workers and intervention studies attempting to replicate CM have often been confounded by differences in energy intake, sleep duration and timing, and eating window duration. We aimed to investigate the effects of CM, induced by delaying mealtimes relative to wake time, independent of sleep timing and duration as well as duration of eating window, on energy expenditure (EE) and substrate oxidation. We hypothesized that CM would reduce EE and increase respiratory quotient (RQ) relative to meals closer to wake time (circadian alignment [CA]). Methods: We used a 2-phase, randomized, crossover study. Men and women (age 20-49 y) were studied under controlled feeding conditions (CA and CM). Each phase included a 10-h eating window at 0900-1900 h (CA) or 1300-2300 h (CM) with fixed mealtimes. Bedtimes were set at 2400-0800 h. Minute-by-minute EE, RQ, and substrate oxidation were obtained over 23 h in a metabolic chamber on d 3-4 and 14-15. Post-meal EE, RQ, and substrate oxidation were calculated as the average of 2-h, 1-h, and 30 min data collections following breakfast, dinner, and snack, respectively. Data were analyzed using a linear mixed effects model including condition, day, and day-by-condition interaction as main predictor variables, and phase as an adjusting covariate. As an exploratory aim, sex-by-condition interaction was also included in the model. Results: Three men and 4 women completed both study phases (age 37.6±8.8 y, BMI 30.8±3.2 kg/m 2 ). EE did not differ between CM and CA. Post-meal RQ for breakfast (p=0.06), dinner (p&lt;0.001), and snack (p&lt;0.001) were higher in CM vs CA. Glucose oxidation after dinner (p&lt;0.001) and snack (p&lt;0.01) were higher in CM vs CA. There were sex-by-condition interactions on EE and glucose oxidation after breakfast (both p=0.06) and dinner (p&lt;0.05), and on EE after snack (p&lt;0.01). In general, CA resulted in greater rise in EE and lesser reduction in glucose oxidation following meals in men compared to women. Conclusion: Delaying mealtimes by 4 h, independent of sleep duration, timing, or diet composition, shifts nutrient metabolism towards greater carbohydrate and lower fat oxidation. Sex may influence the effect of CM on energy metabolism and should be considered in investigations of cardiometabolic risk associated with shift work and late-night eating.

Differential fuel utilization in liver transplant recipients and its relationship with non-alcoholic fatty liver disease.

Metabolic flexibility is the ability to match biofuel availability to utilization. Reduced metabolic flexibility, or lower fatty acid (FA) oxidation in the fasted state, is associated with obesity. The present study evaluated metabolic flexibility after liver transplantation (LT).MethodsPatients receiving LT for non‐alcoholic steatohepatitis (NASH) (n = 35) and non‐NASH (n = 10) were enrolled. NASH was chosen as these patients are at the highest risk of metabolic complications. Metabolic flexibility was measured using whole‐body calorimetry and expressed as respiratory quotient (RQ), which ranges from 0.7 (pure FA oxidation) to 1.0 is (carbohydrate oxidation).ResultsThe two cohorts were similar except for a higher prevalence of obesity and diabetes in the NASH cohort. Post‐prandially, RQ increased in both cohorts (i.e. greater carbohydrate utilization) but peak RQ and time at peak RQ was higher in the NASH cohort. Fasting RQ in NASH was significantly higher (0.845 vs. 0.772, p < .001), indicative of impaired FA utilization. In subgroup analysis of the NASH cohort, body mass index but not liver fat content (MRI‐PDFF) was an independent predictor of fasting RQ. In NASH, fasting RQ inversely correlated with fat‐free muscle volume and directly with visceral adipose tissue.ConclusionReduced metabolic flexibility in patients transplanted for NASH cirrhosis may precede the development of non‐alcoholic fatty liver disease after LT.

What Is the Evidence That Dietary Macronutrient Composition Influences Exercise Performance? A Narrative Review.

The introduction of the needle muscle biopsy technique in the 1960s allowed muscle tissue to be sampled from exercising humans for the first time. The finding that muscle glycogen content reached low levels at exhaustion suggested that the metabolic cause of fatigue during prolonged exercise had been discovered. A special pre-exercise diet that maximized pre-exercise muscle glycogen storage also increased time to fatigue during prolonged exercise. The logical conclusion was that the athlete’s pre-exercise muscle glycogen content is the single most important acutely modifiable determinant of endurance capacity. Muscle biochemists proposed that skeletal muscle has an obligatory dependence on high rates of muscle glycogen/carbohydrate oxidation, especially during high intensity or prolonged exercise. Without this obligatory carbohydrate oxidation from muscle glycogen, optimum muscle metabolism cannot be sustained; fatigue develops and exercise performance is impaired. As plausible as this explanation may appear, it has never been proven. Here, I propose an alternate explanation. All the original studies overlooked one crucial finding, specifically that not only were muscle glycogen concentrations low at exhaustion in all trials, but hypoglycemia was also always present. Here, I provide the historical and modern evidence showing that the blood glucose concentration—reflecting the liver glycogen rather than the muscle glycogen content—is the homeostatically-regulated (protected) variable that drives the metabolic response to prolonged exercise. If this is so, nutritional interventions that enhance exercise performance, especially during prolonged exercise, will be those that assist the body in its efforts to maintain the blood glucose concentration within the normal range.

Differential Effects of One Meal per Day in the Evening on Metabolic Health and Physical Performance in Lean Individuals.

Background: Generally, food intake occurs in a three-meal per 24 h fashion with in-between meal snacking. As such, most humans spend more than ∼ 12–16 h per day in the postprandial state. It may be reasoned from an evolutionary point of view, that the human body is physiologically habituated to less frequent meals. Metabolic flexibility (i.e., reciprocal changes in carbohydrate and fatty acid oxidation) is a characteristic of metabolic health and is reduced by semi-continuous feeding. The effects of time-restricted feeding (TRF) on metabolic parameters and physical performance in humans are equivocal.Methods: To investigate the effect of TRF on metabolism and physical performance in free-living healthy lean individuals, we compared the effects of eucaloric feeding provided by a single meal (22/2) vs. three meals per day in a randomized crossover study. We included 13 participants of which 11 (5 males/6 females) completed the study: age 31.0 ± 1.7 years, BMI 24.0 ± 0.6 kg/m2 and fat mass (%) 24.0 ± 0.6 (mean ± SEM). Participants consumed all the calories needed for a stable weight in either three meals (breakfast, lunch and dinner) or one meal per day between 17:00 and 19:00 for 11 days per study period.Results: Eucaloric meal reduction to a single meal per day lowered total body mass (3 meals/day –0.5 ± 0.3 vs. 1 meal/day –1.4 ± 0.3 kg, p = 0.03), fat mass (3 meals/day –0.1 ± 0.2 vs. 1 meal/day –0.7 ± 0.2, p = 0.049) and increased exercise fatty acid oxidation (p < 0.001) without impairment of aerobic capacity or strength (p > 0.05). Furthermore, we found lower plasma glucose concentrations during the second half of the day during the one meal per day intervention (p < 0.05).Conclusion: A single meal per day in the evening lowers body weight and adapts metabolic flexibility during exercise via increased fat oxidation whereas physical performance was not affected.

NiCo nitride/carbon nanoflakes as low-cost bifunctional electrocatalysts for carbohydrate-assisted electrolytic H2 generation

The sluggish anodic oxygen evolution reaction (OER) still remains the major bottleneck for the electrochemical water splitting to produce hydrogen. Replacing OER with the more thermodynamically favorable carbohydrate oxidation reaction (COR) offers a viable strategy for energy-saving hydrogen production. Herein, we design and fabricate the carbon-coated loose nickel-cobalt nitride nanoflakes (NiCoNx@C) on deliberately coarsened nickel foam (Ni/NF) support through a successive electrodeposition and annealing process, the thus obtained NiCoNx@C/Ni/NF electrocatalyst with hierarchical porous architecture exhibits excellent bifunctional electrocatalytic performance toward both the acidic hydrogen evolution reaction (HER) and the representative alkaline COR. The NiCoNx@C/Ni/NF achieves an ultralow working potential of 1.26 V at 50 mA cm−2 in 1 M KOH with 0.5 M fructose for COR and a small overpotential of 78 mV at 10 mA cm−2 in 0.5 M H2SO4 for HER. We further design an asymmetric-electrolyte electrolyzer, using the bifunctional NiCoNx@C/Ni/NF as both the cathode and anode, which can deliver a current density of 10 mA cm−2 for electrolytic hydrogen production with a rather low applied voltage of 0.67 V and faradaic efficiency approaching 100%, showing great potential to use waste carbohydrates to producing hydrogen energy efficiently.

Feeding Tolerance, Glucose Availability, and Whole-Body Total Carbohydrate and Fat Oxidation in Male Endurance and Ultra-Endurance Runners in Response to Prolonged Exercise, Consuming a Habitual Mixed Macronutrient Diet and Carbohydrate Feeding During Exercise.

Using metadata from previously published research, this investigation sought to explore: (1) whole-body total carbohydrate and fat oxidation rates of endurance (e.g., half and full marathon) and ultra-endurance runners during an incremental exercise test to volitional exhaustion and steady-state exercise while consuming a mixed macronutrient diet and consuming carbohydrate during steady-state running and (2) feeding tolerance and glucose availability while consuming different carbohydrate regimes during steady-state running. Competitively trained male endurance and ultra-endurance runners (n = 28) consuming a balanced macronutrient diet (57 ± 6% carbohydrate, 21 ± 16% protein, and 22 ± 9% fat) performed an incremental exercise test to exhaustion and one of three 3 h steady-state running protocols involving a carbohydrate feeding regime (76–90 g/h). Indirect calorimetry was used to determine maximum fat oxidation (MFO) in the incremental exercise and carbohydrate and fat oxidation rates during steady-state running. Gastrointestinal symptoms (GIS), breath hydrogen (H2), and blood glucose responses were measured throughout the steady-state running protocols. Despite high variability between participants, high rates of MFO [mean (range): 0.66 (0.22–1.89) g/min], Fatmax [63 (40–94) % V̇O2max], and Fatmin [94 (77–100) % V̇O2max] were observed in the majority of participants in response to the incremental exercise test to volitional exhaustion. Whole-body total fat oxidation rate was 0.8 ± 0.3 g/min at the end of steady-state exercise, with 43% of participants presenting rates of ≥1.0 g/min, despite the state of hyperglycemia above resting homeostatic range [mean (95%CI): 6.9 (6.7–7.2) mmol/L]. In response to the carbohydrate feeding interventions of 90 g/h 2:1 glucose–fructose formulation, 38% of participants showed breath H2 responses indicative of carbohydrate malabsorption. Greater gastrointestinal symptom severity and feeding intolerance was observed with higher carbohydrate intakes (90 vs. 76 g/h) during steady-state exercise and was greatest when high exercise intensity was performed (i.e., performance test). Endurance and ultra-endurance runners can attain relatively high rates of whole-body fat oxidation during exercise in a post-prandial state and with carbohydrate provisions during exercise, despite consuming a mixed macronutrient diet. Higher carbohydrate intake during exercise may lead to greater gastrointestinal symptom severity and feeding intolerance.

Metabolic rate and substrate oxidation of young males with obesity at the different sleep stages

ObjectiveInsufficient and poor-quality sleep among young adults is closely related to obesity and may impact metabolic processes. The mobilization and use of endogenous substrates during sleep, especially fat oxidation, is essential for energy metabolism. This study investigated whether there are differences in sleep structure, metabolic rate, substrate oxidation, and the respiratory quotient (RQ) between young males with normal weight and obesity according to sleep stages and overnight sleep. MethodsFifteen young males with normal weight and fifteen with obesity posited electrodes of polysomnography (PSG) and slept in the metabolic chamber for estimation of sleep structure, sleep metabolic rate (SMR), carbohydrate oxidation (CHOO), fat oxidation (FATO), and RQ. Fat-free mass (FFM) was measured by bioelectrical impedance analysis. ResultsThe sleep period time (p = 0.038) and total sleep time (p = 0.032) were significantly shorter in the obesity group than in the normal-weight group. The obesity group also had a longer sleep latency (p = 0.034) and more sleep-turning events (p = 0.018). CHOO/FFM and the RQ were higher in the obesity group while FATO/FFM was significantly higher in the normal-weight group. FATO/FFM was also higher in the normal-weight group in each sleep stage whereas the RQ was higher in the obesity group (p < 0.05). ConclusionsYoung males with obesity showed lower fat oxidation and more dominant carbohydrate-derived fuel oxidation than normal-weight during sleep and experienced shorter sleep periods and total sleep time.

The Therapeutic Effects of Magnesium in Insulin Secretion and Insulin Resistance.

Insulin resistance (IR) is a chronic pathological condition that is related to reduce the rates of glucose uptake, especially in the liver, muscle, and adipose tissue as target tissues. Metabolic syndrome and type 2 diabetes mellitus can occur following progression of the disease. The majority of prior research has applied that some cations such as magnesium (Mg2+) have important physiological role in insulin metabolism. Mg2+ is the fourth most abundant mineral in the human body that gets involved as a cofactor of various enzymes in several metabolic events, such as carbohydrate oxidation, and it has a fundamental role in glucose transporting mechanism of the cell membrane. This cation has numerous duties in the human body such as regulation of insulin secretion in pancreatic beta-cells and phosphorylation of the insulin receptors in target cells and also gets involved in other downstream signal kinases as intracellular cation. On this basis, intracellular Mg2+ balancing is vital for adequate carbohydrate metabolism. This paper summarizes the present knowledge about the therapeutic effects of Mg2+ in reducing IR in liver, muscle, and pancreases with different mechanisms. For this, the search was performed in Google Scholar, PubMed, Scopus, and Web of Science by insulin resistance, skeletal muscle, liver, pancreases, magnesium, Mg2+, and inflammation keywords.

Assessment of the metabolic status of patients with comorbid pathology after COVID-19

&lt;b&gt;Introduction.&lt;/b&gt; Comorbid patients represent one of the most vulnerable groups with an extremely high risk of severe complications and adverse outcomes of COVID-19. Multiple organ damage in COVID-19 is associated with pathology of the cardiovascular system, diabetes mellitus, chronic obstructive pulmonary disease, chronic inflammatory bowel disease, and liver disease. The management of these patients requires an integrated approach, and therefore the need for optimal nutritional support is essential. &lt;b&gt;Materials and methods.&lt;/b&gt; 36 patients with comorbid pathology with a history of COVID-19 (10-70% of lung involvement) 1.5-12 months prior to the study were examined. The metabolic and clinical status of patients was assessed using general clinical, laboratory and functional (bioelectrical impedance) research methods. &lt;b&gt;Results.&lt;/b&gt; The analysis showed an increased rate of fat oxidation, a decrease in the rate of carbohydrate oxidation, and the absence of significant changes in the rate of protein oxidation. &lt;b&gt;Conclusion.&lt;/b&gt; The data obtained are of practical importance for the development of recommendations and correction of the nutritional status of this group of patients.

Carbohydrate structure-activity relations of Au-catalysed base-free oxidations: gold displaying a platinum lustre.

This paper describes the base-free gold-catalysed oxidation of four different carbohydrates in a packed bed plug flow reactor. The influence of the carbohydrate structure on the catalytic activity and selectivity was investigated by comparing two neutral sugars (glucose (Glc) and galactose (Gal), both with primary alcohols at C6), with their sugar-acid analogues (glucuronic acid (GlcA) and galacturonic acid (GalA), both with carboxylic acids at C6). The orientation of OH-groups at the C4-position (equatorial in Glc/GlcA and axial in Glc/GlcA), and the C6-functionality (primary alcohols in Gal/Glc and carboxylic acids in GalA/GlcA) has a profound influence on the catalytic activity. When the OH-groups are in an axial position their reactivity was higher compared to the OH-groups in the equatorial position for both the sugars and the sugar acids. In addition the reactivity of carbohydrates over Au-catalysts under base-free conditions is different compared to alkaline conditions, and is more in line with a Pt-catalysed dehydrogenation mechanism.