Ingesting Isomaltulose Versus Fructose-Maltodextrin During Prolonged Moderate-Heavy Exercise Increases Fat Oxidation but Impairs Gastrointestinal Comfort and Cycling Performance

2015 ◽  
Vol 25 (5) ◽  
pp. 427-438 ◽  
Author(s):  
Tanja Oosthuyse ◽  
Matthew Carstens ◽  
Aletta M.E. Millen
Keyword(s):  
Blood Glucose ◽  
Exercise Performance ◽  
Glucose Concentration ◽  
Metabolic Response ◽  
Blood Glucose Concentration ◽  
Gastrointestinal Symptoms ◽  
Time Trial ◽  
Fat Oxidation ◽  
Metabolic Effects ◽  
Nonesterified Fatty Acid

Certain commercial carbohydrate replacement products include slowly absorbed carbohydrates such as isomaltulose. Few studies have investigated the metabolic effects of ingesting isomaltulose during exercise and none have evaluated exercise performance and gastrointestinal comfort. Nine male cyclists participated postprandially during three trials of 2-h steady-state (S-S) exercise (60% Wmax) followed by a 16 km time trial (TT) while ingesting 63 g∙h-1 of either, 0.8:1 fructose: maltodextrin (F:M) or isomaltulose (ISO) or placebo-flavored water (PL). Data were analyzed by magnitude-based inferences. During S-S exercise, ISO and PL similarly increased plasma nonesterified fatty acid (NEFA) concentration (mean change ISO versus F:M: 0.18, 90%CI ± 0.21 mmol∙L-1, 88% likelihood) and fat oxidation (10, 90%CI ± 9 g, 89% likelihood) while decreasing carbohydrate oxidation (-36, 90%CI ± 30.2 g, 91% likelihood) compared with F:M, despite equal elevations in blood glucose concentration with ISO and F:M. Rating of stomach cramps and bloating increased progressively with ISO (rating: 0-90 min S-S, weak; 120 min S-S, moderate; TT, strong) compared with F:M and PL (0-120 min S-S and TT, very weak). TT performance was substantially slower with ISO (mean change: 1.5, 90%CI ± 1.4 min, 94% likely harmful) compared with F:M. The metabolic response of ISO ingestion during moderate exercise to increase NEFA availability and fat oxidation despite elevating blood glucose concentration is anomalous for a carbohydrate supplement. However, ingesting isomaltulose at a continuous high frequency to meet the recommended carbohydrate replacement dose, results in severe gastrointestinal symptoms during prolonged or high intensity exercise and negatively affects exercise performance compared with fructose-maltodextrin supplementation.

Metabolic effects of dobutamine in normal man

1992 ◽  
Vol 82 (1) ◽  
pp. 77-83 ◽  
Author(s):  
Ceri J. Green ◽  
R. S. Frazer ◽  
S. Underhill ◽  
Paula Maycock ◽  
Judith A. Fairhurst ◽  
...  
Keyword(s):  
Heart Rate ◽  
Blood Glucose ◽  
Glucose Concentration ◽  
Respiratory Exchange Ratio ◽  
Blood Glucose Concentration ◽  
Plasma Potassium ◽  
Metabolic Effects ◽  
Dobutamine Infusion ◽  
Plasma Insulin Concentration ◽  
Placebo Infusion

1. Dobutamine in 5% (w/v) d-glucose was infused at sequential doses of 2, 5 and 10 μg min−1 kg−1, 45 min at each dose, into eight healthy male subjects, and the effects were compared with those produced by infusion of the corresponding volumes of 5% (w/v) d-glucose alone. 2. The energy expenditure increased and was 33% higher than control (P<0.001) at 10 μg of dobutamine min−1 kg−1. The respiratory exchange ratio decreased from 0.85 (sem 0.02) before infusion to 0.80 (sem 0.01) at 10 μg of dobutamine min−1 kg−1, but did not alter during the placebo infusion (P> 0.001). 3. Plasma noradrenaline concentrations were lower during the dobutamine infusion compared with during the infusion of d-glucose alone (P < 0.025). Plasma dopamine concentrations remained below 0.1 nmol/l throughout both infusions. 4. Compared with during the placebo infusion, the blood glucose concentration decreased (P < 0.001), the plasma glycerol and free fatty acid concentrations increased by 150 and 225%, respectively (both P < 0.001), and the plasma potassium concentration decreased from 3.8 (sem 0.07) to 3.6 (sem 0.04) mmol/l (P<0.01) during dobutamine infusion. The plasma insulin concentration increased at 2 and 5 μg of dobutamine min−1 kg−1 (P<0.001) with no further rise at 10 μg of dobutamine min−1 kg−1. 5. Compared with during the placebo infusion, the systolic and diastolic blood pressures and the heart rate increased during dobutamine infusion (P<0.01). At 10 μg of dobutamine min−1 kg−1, the systolic blood pressure was around 160 mmHg (P < 0.001) and the heart rate was around 92 (sem 8) beats/min compared with 59 (sem 4) beats/min during the placebo infusion (P < 0.001). 6. Dobutamine has metabolic effects. It is markedly thermogenic and lipolytic. It depresses the respiratory exchange ratio and endogenous noradrenaline secretion, stimulates insulin secretion and depresses the blood glucose concentration.

scholarly journals Beneficial metabolic adaptations due to endurance exercise training in the fasted state

2011 ◽  
Vol 110 (1) ◽  
pp. 236-245 ◽  
Author(s):  
Karen Van Proeyen ◽  
Karolina Szlufcik ◽  
Henri Nielens ◽  
Monique Ramaekers ◽  
Peter Hespel
Keyword(s):  
Blood Glucose ◽  
Glucose Concentration ◽  
Citrate Synthase ◽  
Blood Glucose Concentration ◽  
Fat Oxidation ◽  
Oxidative Capacity ◽  
Type I ◽  
Substrate Selection ◽  
Fasted State ◽  
Exercise Induced

Training with limited carbohydrate availability can stimulate adaptations in muscle cells to facilitate energy production via fat oxidation. Here we investigated the effect of consistent training in the fasted state, vs. training in the fed state, on muscle metabolism and substrate selection during fasted exercise. Twenty young male volunteers participated in a 6-wk endurance training program (1–1.5 h cycling at ∼70% V̇o2max, 4 days/wk) while receiving isocaloric carbohydrate-rich diets. Half of the subjects trained in the fasted state (F; n = 10), while the others ingested ample carbohydrates before (∼160 g) and during (1 g·kg body wt−1·h−1) the training sessions (CHO; n = 10). The training similarly increased V̇o2max (+9%) and performance in a 60-min simulated time trial (+8%) in both groups ( P < 0.01). Metabolic measurements were made during a 2-h constant-load exercise bout in the fasted state at ∼65% pretraining V̇o2max. In F, exercise-induced intramyocellular lipid (IMCL) breakdown was enhanced in type I fibers ( P < 0.05) and tended to be increased in type IIa fibers ( P = 0.07). Training did not affect IMCL breakdown in CHO. In addition, F (+21%) increased the exercise intensity corresponding to the maximal rate of fat oxidation more than did CHO (+6%) ( P < 0.05). Furthermore, maximal citrate synthase (+47%) and β-hydroxyacyl coenzyme A dehydrogenase (+34%) activity was significantly upregulated in F ( P < 0.05) but not in CHO. Also, only F prevented the development exercise-induced drop in blood glucose concentration ( P < 0.05). In conclusion, F is more effective than CHO to increase muscular oxidative capacity and at the same time enhances exercise-induced net IMCL degradation. In addition, F but not CHO prevented drop of blood glucose concentration during fasting exercise.

Metabolic Effects of Low-Dose Dopamine Infusion in Normal Volunteers

1990 ◽  
Vol 79 (6) ◽  
pp. 605-611 ◽  
Author(s):  
Cathy J. Regan ◽  
R. Duckworth ◽  
Judith A. Fairhurst ◽  
Paula F. Maycock ◽  
K. N. Frayn ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Fatty Acid ◽  
Blood Glucose ◽  
Free Fatty Acid ◽  
Energy Expenditure ◽  
Glucose Concentration ◽  
Respiratory Exchange Ratio ◽  
Blood Glucose Concentration ◽  
Metabolic Effects ◽  
Dopamine Infusion

1. Dopamine in 5% (w/v) d-glucose was infused into five healthy male volunteers at doses of 2, 5 and 10 μg min−1 kg−1 over three sequential periods of 45 min each. 2. Oxygen consumption, respiratory exchange ratio, blood glucose concentration and plasma levels of free fatty acids, glycerol, lactate, dopamine, adrenaline and noradrenaline were measured. The results were compared with values obtained during infusion over the same time period of the corresponding volumes of 5% (w/v) d-glucose alone. 3. Energy expenditure calculated from the oxygen consumption and the respiratory exchange ratio was higher than control values during infusion of dopamine (P < 0.001, analysis of variance) specifically at a rate of 10 μg min−1 kg−1 (P < 0.05) when it was 14% higher, but not at a rate 2 of or 5 μg min−1 kg−1. The plasma noradrenaline concentration was 74 and 230% and the blood glucose concentration was 21 and 36% higher than control values at 5 and 10 μg of dopamine min−1 kg−1, respectively (P < 0.01). At 10 μg of dopamine min−1 kg−1 the plasma free fatty acid concentration was 70% and the plasma glycerol concentration was 80% higher than during the control infusion (P < 0.01). The respiratory exchange ratio and the plasma lactate concentration were the same in the two groups and did not alter during the dopamine infusion. The plasma adrenaline concentration rose significantly (P < 0.01), but only transiently, during dopamine infusion at a rate of 2 μg min−1 kg−1. 4. Dopamine at low doses has metabolic effects. It increases the blood glucose concentration and the circulating noradrenaline level at an infusion rate of 5 μg min−1 kg−1. It increases energy expenditure and circulating free fatty acid and glycerol levels at an infusion rate of 10 μg min−1 kg−1, presumably due to stimulation of lipolysis.

Addition of sodium alginate and pectin to a carbohydrate-electrolyte solution does not influence substrate oxidation, gastrointestinal comfort, or cycling performance

2020 ◽  
Vol 45 (6) ◽  
pp. 675-678
Author(s):  
Stephen A. Mears ◽  
James Worley ◽  
George S. Mason ◽  
Carl J. Hulston ◽  
Lewis J. James
Keyword(s):  
Blood Glucose ◽  
Sodium Alginate ◽  
Electrolyte Solution ◽  
Blood Glucose Concentration ◽  
Gastrointestinal Symptoms ◽  
Time Trial ◽  
Carbon Dioxide Production ◽  
Cycling Performance ◽  
Substrate Oxidation ◽  
Maximal Power

Eight well-trained cyclists ingested 68 g·h−1 of a carbohydrate-electrolyte solution with sodium alginate and pectin (CHO-ALG) or a taste and carbohydrate type-matched carbohydrate-electrolyte solution (CHO) during 120 min of cycling at 55% maximal power followed by an ∼20 min time trial. Oxygen uptake, carbon dioxide production, blood glucose concentration, substrate oxidation, gastrointestinal symptoms, and time trial performance (CHO-ALG: 1219 ± 84 s, CHO: 1267 ± 102 s; P = 0.185) were not different between trials. Novelty Inclusion of sodium alginate and pectin in a carbohydrate drink does not influence blood glucose, substrate oxidation, gastrointestinal comfort, or performance in cyclists.

scholarly journals FGF19 in the Hindbrain Lowers Blood Glucose and Alters Excitability of Vagal Motor Neurons in Hyperglycemic Mice

Endocrinology ◽  
2021 ◽  
Vol 162 (4) ◽  
Author(s):  
Jordan B Wean ◽  
Bret N Smith
Keyword(s):  
Blood Glucose ◽  
Growth Factor ◽  
Fibroblast Growth Factor ◽  
Motor Neurons ◽  
Glucose Concentration ◽  
Blood Glucose Concentration ◽  
Metabolic Effects ◽  
Fibroblast Growth ◽  
Fibroblast Growth Factor Receptors ◽  
Dorsal Hindbrain

Abstract Fibroblast growth factor 19 (FGF19) is a protein hormone that produces antidiabetic effects when administered intracerebroventricularly in the forebrain. However, no studies have examined how FGF19 affects hindbrain neurons that participate directly in autonomic control of systemic glucose regulation. Within the dorsal hindbrain, parasympathetic motor neurons of the dorsal motor nucleus of the vagus (DMV) express fibroblast growth factor receptors and their activity regulates visceral homeostatic processes, including energy balance. This study tested the hypothesis that FGF19 acts in the hindbrain to alter DMV neuron excitability and lower blood glucose concentration. Fourth ventricle administration of FGF19 produced no effect on blood glucose concentration in control mice, but induced a significant, peripheral muscarinic receptor-dependent decrease in systemic hyperglycemia for up to 12 h in streptozotocin-treated mice, a model of type 1 diabetes. Patch-clamp recordings from DMV neurons in vitro revealed that FGF19 application altered synaptic and intrinsic membrane properties of DMV neurons, with the balance of FGF19 effects being significantly modified by a recent history of systemic hyperglycemia. These findings identify central parasympathetic circuitry as a novel target for FGF19 and suggest that FGF19 acting in the dorsal hindbrain can alter vagal output to produce its beneficial metabolic effects.

Review: Starch Matrices and the Glycemic Response

2011 ◽  
Vol 17 (3) ◽  
pp. 187-204 ◽  
Author(s):  
J. Parada ◽  
J.M. Aguilera
Keyword(s):  
Blood Glucose ◽  
Glucose Concentration ◽  
Blood Glucose Concentration ◽  
Present Knowledge ◽  
Metabolic Effects ◽  
Postprandial Blood Glucose ◽  
Glycemic Response ◽  
Food Matrix

Starch is the most important source of energy for humans, and it is present in many products derived from cereals, legumes and tubers. Interestingly, some of these food products can have different metabolic effects (e.g. change of postprandial blood glucose concentration) although the total amount of starch is the same. This review focuses on a microstructural perspective of the glycemic response, in search of an alternative and complementary explanation of this phenomenon. Several starch and food microstructures are responsible for the change in starch bioaccessibility. Aspects such as the characterization of the microstructure of starchy products and, its relation to the metabolic problem, the crucial role of the food matrix and other components in the ingested meal, and the gaps in our present knowledge are discussed.

Comparison between Carbohydrate Feedings before and during Exercise on Running Performance during a 30-km Treadmill Time Trial

1994 ◽  
Vol 4 (4) ◽  
pp. 374-386 ◽  
Author(s):  
Costas Chryssanthopoulos ◽  
Clyde Williams ◽  
Wendy Wilson ◽  
Lucy Asher ◽  
Lynda Hearne
Keyword(s):  
Blood Glucose ◽  
Electrolyte Solution ◽  
Glucose Concentration ◽  
Blood Glucose Concentration ◽  
Time Trial ◽  
Treadmill Running ◽  
Endurance Running ◽  
Running Performance ◽  
Performance Times ◽  
Carbohydrate Meal

The purpose of this study was to compare the effects of a carbohydrate-electrolyte solution, ingested during exercise, with the effects of a preexercise carbohydrate meal on endurance running performance. Ten endurance-trained males completed two 30-km treadmill runs. In one trial subjects consumed a placebo solution 4 hr before exercise and a carbohydrate-electrolyte solution immediately before exercise and every 5 km (C). In the other trial, subjects consumed a 4-hr preexercise high-carbohydrate meal and water immediately before exercise and every 5 km (M). Performance times were identical for M and C, and there was no difference in the self-selected speeds. Oxygen uptake, heart rates, perceived rate of exertion, and respiratory exchange ratios were also similar. However, blood glucose concentration was higher in C during the first 20 km of the 30-km run. In M, blood glucose concentration was maintained above 4.5 mmol ·throughout exercise. Thus, the two conditions produced the same 30-km treadmill running performance time.

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