scholarly journals Substrate source utilization during moderate intensity exercise with glucose ingestion in Type 1 diabetic patients

2007 ◽  
Vol 103 (1) ◽  
pp. 119-124 ◽  
Author(s):  
M. Robitaille ◽  
M.-C. Dubé ◽  
S. J. Weisnagel ◽  
D. Prud'homme ◽  
D. Massicotte ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Plasma Glucose ◽  
Muscle Glycogen ◽  
Maximal Oxygen Uptake ◽  
Glucose Oxidation ◽  
Substrate Oxidation ◽  
Moderate Intensity ◽  
Diabetic Patients ◽  
Control Subjects ◽  
Exogenous Glucose

Substrate oxidation and the respective contributions of exogenous glucose, glucose released from the liver, and muscle glycogen oxidation were measured by indirect respiratory calorimetry combined with tracer technique in eight control subjects and eight diabetic patients (5 men and 3 women in both groups) of similar age, height, body mass, and maximal oxygen uptake, over a 60-min exercise period on cycle ergometer at 50.8% (SD 4.0) maximal oxygen uptake [131.0 W (SD 38.2)]. The subjects and patients ingested a breakfast (containing ∼80 g of carbohydrates) 3 h before and 30 g of glucose (labeled with 13C) 15 min before the beginning of exercise. The diabetic patients also received their usual insulin dose [Humalog = 9.1 U (SD 0.9); Humulin N = 13.9 U (SD 4.4)] immediately before the breakfast. Over the last 30 min of exercise, the oxidation of carbohydrate [1.32 g/min (SD 0.48) and 1.42 g/min (SD 0.63)] and fat [0.33 g/min (SD 0.10) and 0.30 g/min (SD 0.10)] and their contribution to the energy yield were not significantly different in the control subjects and diabetic patients. Exogenous glucose oxidation was also not significantly different in the control subjects and diabetic patients [6.3 g/30 min (SD 1.3) and 5.2 g/30 min (SD 1.6), respectively]. In contrast, the oxidation of plasma glucose and oxidation of glucose released from the liver were significantly lower in the diabetic patients than in control subjects [14.5 g/30 min (SD 4.3) and 9.3 g/30 min (SD 2.8) vs. 27.9 g/30 min (SD 13.3) and 21.6 g/30 min (SD 12.8), respectively], whereas that of muscle glycogen was significantly higher [28.1 g/30 min (SD 15.5) vs. 11.6 g/30 min (SD 8.1)]. These data indicate that, compared with control subjects, in diabetic patients fed glucose before exercise, substrate oxidation and exogenous glucose oxidation overall are similar but plasma glucose oxidation is lower; this is associated with a compensatory higher utilization of muscle glycogen.

scholarly journals Oral [13C]glucose oxidation during prolonged exercise after high- and low-carbohydrate diets

1998 ◽  
Vol 85 (2) ◽  
pp. 723-730 ◽  
Author(s):  
F. Péronnet ◽  
N. Rhéaume ◽  
C. Lavoie ◽  
C. Hillaire-Marcel ◽  
D. Massicotte
Keyword(s):  
Oxygen Uptake ◽  
Plasma Glucose ◽  
Muscle Glycogen ◽  
Maximal Oxygen Uptake ◽  
Oxidation Rate ◽  
Glucose Oxidation ◽  
Prolonged Exercise ◽  
Exogenous Glucose ◽  
Low Carbohydrate ◽  
The Difference

The effect of a diet either high or low in carbohydrates (CHO) on exogenous 13C-labeled glucose oxidation (200 g) during exercise (ergocycle: 120 min at 64.0 ± 0.5% maximal oxygen uptake) was studied in six subjects. Between 40 and 80 min, exogenous glucose oxidation was significantly higher after the diet low in CHO (0.63 ± 0.05 vs. 0.52 ± 0.04 g/min), but this difference disappeared between 80 and 120 min (0.71 ± 0.03 vs. 0.69 ± 0.04 g/min). The oxidation rate of plasma glucose, computed from the volume of13CO2produced the13C-to-12C ratio in plasma glucose at 80 min, and of glucose released from the liver, computed from the difference between plasma glucose and exogenous glucose oxidation, was higher after the diet low in CHO (1.68 ± 0.26 vs. 1.41 ± 0.17 and 1.02 ± 0.20 vs. 0.81 ± 0.14 g/min, respectively). In contrast the oxidation rate of glucose plus lactate from muscle glycogen (computed from the difference between total CHO oxidation and plasma glucose oxidation) was lower (0.31 ± 0.35 vs. 1.59 ± 0.20 g/min). After a diet low in CHO, the oxidation of exogenous glucose and of glucose released from the liver is increased and partly compensates for the reduction in muscle glycogen availability and oxidation.

Oxidation of an oral [13C]glucose load at rest and prolonged exercise in trained and sedentary subjects

1999 ◽  
Vol 86 (1) ◽  
pp. 52-60 ◽  
Author(s):  
Y. Burelle ◽  
F. Péronnet ◽  
S. Charpentier ◽  
C. Lavoie ◽  
C. Hillaire-Marcel ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Plasma Glucose ◽  
Muscle Glycogen ◽  
Glucose Oxidation ◽  
Prolonged Exercise ◽  
Glucose Load ◽  
Exogenous Glucose ◽  
Glycogen Stores ◽  
Male Subjects ◽  
Sedentary Subjects

The purpose of this study was to compare the oxidation of [13C]glucose (100 g) ingested at rest or during exercise in six trained (TS) and six sedentary (SS) male subjects. The oxidation of plasma glucose was also computed from the volume of13CO2and13C/12C in plasma glucose to compute the oxidation rate of glucose released from the liver and from glycogen stores in periphery (mainly muscle glycogen stores during exercise). At rest, oxidative disposal of both exogenous (8.3 ± 0.3 vs. 6.6 ± 0.8 g/h) and liver glucose (4.4 ± 0.5 vs. 2.6 ± 0.4 g/h) was higher in TS than in SS. This could contribute to the better glucose tolerance observed at rest in TS. During exercise, for the same absolute workload [140 ± 5 W: TS = 47 ± 2.5; SS = 68 ± 3 %maximal oxygen uptake (V˙o 2 max)], [13C]glucose oxidation was higher in TS than in SS (39.0 ± 2.6 vs. 33.6 ± 1.2 g/h), whereas both liver glucose (16.8 ± 2.4 vs. 24.0 ± 1.8 g/h) and muscle glycogen oxidation (36.0 ± 3.0 vs. 51.0 ± 5.4 g/h) were lower. For the same relative workload (68 ± 3% V˙o 2 max: TS = 3.13 ± 0.96; SS = 2.34 ± 0.60 l O2/min), exogenous glucose (44.4 ± 1.8 vs. 33.6 ± 1.2 g/h) and muscle glycogen oxidation (73.8 ± 7.2 vs. 51.0 ± 5.4 g/h) were higher in TS. However, despite a higher energy expenditure in TS, liver glucose oxidation was similar in both groups (22.2 ± 3.0 vs. 24.0 ± 1.8 g/h). Thus exogenous glucose oxidation was selectively favored in TS during exercise, reducing both liver glucose and muscle glycogen oxidation.

Heat stress increases muscle glycogen use but reduces the oxidation of ingested carbohydrates during exercise

2002 ◽  
Vol 92 (4) ◽  
pp. 1562-1572 ◽  
Author(s):  
Roy L. P. G. Jentjens ◽  
Anton J. M. Wagenmakers ◽  
Asker E. Jeukendrup
Keyword(s):  
Plasma Glucose ◽  
Muscle Glycogen ◽  
Oxidation Rate ◽  
Glucose Oxidation ◽  
Statistical Significance ◽  
Maximal Oxygen Consumption ◽  
Exogenous Glucose ◽  
Cool Environment ◽  
Lower Plasma Glucose ◽  
Glucose Plasma

The aim of the present study was to test the hypothesis that the oxidation rate of ingested carbohydrate (CHO) is impaired during exercise in the heat compared with a cool environment. Nine trained cyclists (maximal oxygen consumption 65 ± 1 ml · kg body wt−1 · min−1) exercised on two different occasions for 90 min at 55% maximum power ouptput at an ambient temperature of either 16.4 ± 0.2°C (cool trial) or 35.4 ± 0.1°C (heat trial). Subjects received 8% glucose solutions that were enriched with [U-13C]glucose for measurements of exogenous glucose, plasma glucose, liver-derived glucose and muscle glycogen oxidation. Exogenous glucose oxidation during the final 30 min of exercise was significantly ( P < 0.05) lower in the heat compared with the cool trial (0.76 ± 0.06 vs. 0.84 ± 0.05 g/min). Muscle glycogen oxidation during the final 30 min of exercise was increased by 25% in the heat (2.07 ± 0.16 vs. 1.66 ± 0.09 g/min; P < 0.05), and liver-derived glucose oxidation was not different. There was a trend toward a higher total CHO oxidation and a lower plasma glucose oxidation in the heat although this did not reach statistical significance ( P = 0.087 and P = 0.082, respectively). These results demonstrate that the oxidation rate of ingested CHO is reduced and muscle glycogen utilization is increased during exercise in the heat compared with a cool environment.

Gender differences in glucose kinetics and substrate oxidation during exercise near the lactate threshold

2002 ◽  
Vol 92 (3) ◽  
pp. 1125-1132 ◽  
Author(s):  
Brent C. Ruby ◽  
Andrew R. Coggan ◽  
Ted W. Zderic
Keyword(s):  
Blood Glucose ◽  
Plasma Glucose ◽  
Muscle Glycogen ◽  
Lactate Threshold ◽  
Substrate Oxidation ◽  
Fat Free Mass ◽  
Moderate Intensity ◽  
Glucose Kinetics ◽  
Men And Women ◽  
Relative Contribution

The purpose of this investigation was to determine plasma glucose kinetics and substrate oxidation in men and women during exercise relative to the lactate threshold (LT). Subjects cycled for 25 min at 70 and 90% of O2 uptake (V˙o 2) at LT (70 and 90% LT, respectively). Plasma glucose appearance (Ra) and disappearance (Rd) were determined with a primed constant infusion of [6,6-2H]glucose. There were no significant differences in glucose Ra between men [22.6 ± 1.9 and 39.9 ± 3.9 μmol · kg fat-free mass (FFM)−1 · min−1 for 70 and 90% LT, respectively] and women (22.3 ± 2.7 and 33.9 ± 5.7 μmol · kg FFM−1 · min−1 for 70 and 90% LT, respectively). Similarly, there were no significant differences in glucose Rd between men (21.2 ± 1.9 and 38.1 ± 3.7 μmol · kg FFM−1 · min−1 for 70 and 90% LT, respectively) and women (21.3 ± 2.8 and 33.3 ± 5.6 μmol · kg FFM−1 · min−1 for 70 and 90% LT, respectively). Although there were no differences between genders in the relative contribution of carbohydrate (CHO) to total energy expenditure, the relative contribution of muscle glycogen to total CHO oxidation (75.8 ± 3.2 and 64.2 ± 8.0% for men and women, respectively, at 70% LT and 75.1 ± 2.6 and 60.1 ± 11.2% for men and women, respectively, at 90% LT) was lower in women. Consequently, the relative contribution of blood glucose to total CHO oxidation was significantly higher in women. These results indicate that although plasma glucose Ra and Rdare similar in men and women, the relative contribution of muscle glycogen and blood glucose is significantly different in women during moderate-intensity exercise relative to LT.

Plasma glucose kinetics during exercise in subjects with high and low lactate thresholds

1992 ◽  
Vol 73 (5) ◽  
pp. 1873-1880 ◽  
Author(s):  
A. R. Coggan ◽  
W. M. Kohrt ◽  
R. J. Spina ◽  
J. P. Kirwan ◽  
D. M. Bier ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Plasma Glucose ◽  
Glucose Oxidation ◽  
Citrate Synthase ◽  
Metabolic Response ◽  
Vastus Lateralis ◽  
Cycle Ergometer ◽  
Vastus Lateralis Muscle ◽  
Respiratory Capacity ◽  
Group A

The purpose of this study was to test the hypothesis that the rate of plasma glucose oxidation during exercise is inversely related to muscle respiratory capacity. To this end, 14 subjects were studied: in 7 of these subjects, the blood lactate threshold (LT) occurred at a relatively high intensity [i.e., at 65 +/- 2% of peak cycle ergometer oxygen uptake (VO2 peak)], whereas in the other 7 subjects, LT occurred at a relatively low intensity (i.e., at 45 +/- 2% of VO2 peak). VO2peak did not differ between the two groups, but citrate synthase activity in the vastus lateralis muscle was 53% higher (P < 0.05) in the high LT group. A primed continuous infusion of [U-13C]glucose was used to quantify rates of glucose appearance (Ra), disappearance (Rd), and oxidation (R(ox)) during 90 min of exercise at 55% VO2peak. Although both absolute and relative rates of oxygen uptake during exercise were similar in the two groups, mean Ra and Rd were 17% lower (P < 0.001) in the high LT group, and mean R(ox) was 25% lower (21.0 +/- 2.6 vs. 27.9 +/- 2.6 mumol.min-1.kg-1; P < 0.001). The percentage of total energy derived from glucose oxidation was inversely related to muscle citrate synthase activity (r = -0.85; P < 0.01). These data support the concept that skeletal muscle respiratory capacity has a major role in determining the metabolic response to submaximal exercise.

Long-lasting exercise involvement protects against decline in V̇O2max and V̇O2 kinetics in moderately active women

2020 ◽  
pp. 1-9
Author(s):  
Damir Zubac ◽  
Vladimir Ivančev ◽  
Zoran Valić ◽  
Boštjan Šimunič
Keyword(s):  
Oxygen Uptake ◽  
Maximal Oxygen Uptake ◽  
Near Infrared ◽  
Cardiovascular Response ◽  
Cardiopulmonary Exercise Testing ◽  
Age Groups ◽  
Moderate Intensity ◽  
Maximal Heart Rate ◽  
Middle Aged ◽  
Pulmonary Oxygen Uptake

We studied the effects of age on different physiological parameters, including those derived from (i) maximal cardiopulmonary exercise testing (CPET), (ii) moderate-intensity step transitions, and (iii) tensiomyography (TMG)-derived variables in moderately active women. Twenty-eight women (age, 19 to 53 years), completed 3 laboratory visits, including baseline data collection, TMG assessment, maximal oxygen uptake test via CPET, and a step-transition test from 20 W to a moderate-intensity cycling power output (PO), corresponding to oxygen uptake at 90% gas exchange threshold. During the step transitions, breath-by-breath pulmonary oxygen uptake, near infrared spectroscopy derived muscle deoxygenation (ΔHHb), and beat-by-beat cardiovascular response were continuously monitored. There were no differences observed between the young and middle-aged women in their maximal oxygen uptake and peak PO, while the maximal heart rate (HR) was 12 bpm lower in middle-aged compared with young (p = 0.016) women. Also, no differences were observed between the age groups in τ pulmonary oxygen uptake, ΔHHb, and τHR during on-transients. The first regression model showed that age did not attenuate the maximal CPET capacity in the studied population (p = 0.638), while in the second model a faster τ pulmonary oxygen uptake, combined with shorter TMG-derived contraction time (Tc) of the vastus lateralis (VL), were associated with a higher maximal oxygen uptake (∼30% of explained variance, p = 0.039). In conclusion, long lasting exercise involvement protects against a maximal oxygen uptake and τpulmonary oxygen uptake deterioration in moderately active women. Novelty: Faster τ pulmonary oxygen uptake and shorter Tc of the VL explain 33% of the variance in superior maximal oxygen uptake attainment. No differences between age groups were found in τ pulmonary oxygen uptake, τΔHHb, and τHR during on-transients.

Epinephrine inhibits exogenous glucose utilization in exercising horses

2000 ◽  
Vol 88 (5) ◽  
pp. 1777-1790 ◽  
Author(s):  
Raymond J. Geor ◽  
Kenneth W. Hinchcliff ◽  
Laura Jill McCutcheon ◽  
Richard A. Sams
Keyword(s):  
Muscle Glycogen ◽  
Glucose Utilization ◽  
Treadmill Exercise ◽  
Moderate Intensity ◽  
Oral Glucose ◽  
Moderate Intensity Exercise ◽  
Epinephrine Infusion ◽  
Glucose Administration ◽  
Exogenous Glucose ◽  
Glycogen Utilization

This study examined the effects of preexercise glucose administration, with and without epinephrine infusion, on carbohydrate metabolism in horses during exercise. Six horses completed 60 min of treadmill exercise at 55 ± 1% maximum O2 uptake 1) 1 h after oral administration of glucose (2 g/kg; G trial); 2) 1 h after oral glucose and with an intravenous infusion of epinephrine (0.2 μmol ⋅ kg− 1 ⋅ min− 1; GE trial) during exercise, and 3) 1 h after water only (F trial). Glucose administration (G and GE) caused hyperinsulinemia and hyperglycemia (∼8 mM). In GE, plasma epinephrine concentrations were three- to fourfold higher than in the other trials. Compared with F, the glucose rate of appearance was ∼50% and ∼33% higher in G and GE, respectively, during exercise. The glucose rate of disappearance was ∼100% higher in G than in F, but epinephrine infusion completely inhibited the increase in glucose uptake associated with glucose administration. Muscle glycogen utilization was higher in GE [349 ± 44 mmol/kg dry muscle (dm)] than in F (218 ± 28 mmol/kg dm) and G (201 ± 35 mmol/kg dm). We conclude that 1) preexercise glucose augments utilization of plasma glucose in horses during moderate-intensity exercise but does not alter muscle glycogen usage and 2) increased circulating epinephrine inhibits the increase in glucose rate of disappearance associated with preexercise glucose administration and increases reliance on muscle glycogen for energy transduction.

Metabolic and performance responses during endurance exercise after high-fat and high-carbohydrate meals

1998 ◽  
Vol 85 (2) ◽  
pp. 418-424 ◽  
Author(s):  
Helena A. Whitley ◽  
S. M. Humphreys ◽  
I. T. Campbell ◽  
M. A. Keegan ◽  
T. D. Jayanetti ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Oxygen Uptake ◽  
Endurance Exercise ◽  
Maximal Oxygen Uptake ◽  
Time Trial ◽  
Substrate Oxidation ◽  
High Fat ◽  
High Carbohydrate ◽  
And Performance ◽  
Fat Meal

We studied the effects of preexercise meal composition on metabolic and performance-related variables during endurance exercise. Eight well-trained cyclists (maximal oxygen uptake 65.0 to 83.5 ml ⋅ kg−1 ⋅ min−1) were studied on three occasions after an overnight fast. They were given isoenergetic meals containing carbohydrate (CHO), protein (P), and fat (F) in the following amounts (g/70 kg body wt): high-carbohydrate meal, 215 CHO, 26 P, 3 F; high-fat meal, 50 CHO, 14 P, 80 F. On the third occasion subjects were studied after an overnight fast. Four hours after consumption of the meal, subjects started exercise for 90 min at 70% of their maximal oxygen uptake, followed by a 10-km time trial. The high-carbohydrate meal compared with the high-fat meal resulted in significant decreases ( P < 0.05) in blood glucose, plasma nonesterified fatty acids, plasma glycerol, plasma chylomicron-triacylglycerol, and plasma 3-hydroxybutyrate concentrations during exercise. This was accompanied by an increase in plasma insulin ( P < 0.01 vs. no meal), plasma epinephrine, and plasma growth hormone concentrations (each P < 0.05 vs. either of the other conditions) during exercise. Despite these large differences in substrate and hormone concentrations in plasma, substrate oxidation during the 90-min exercise period was similar in the three trials, and there were no differences in performance on the time trial. These results suggest that, although the availability of fatty acids and other substrates in plasma can be markedly altered by dietary means, the pattern of substrate oxidation during endurance exercise is remarkably resistant to alteration.

scholarly journals Similar rates of fat oxidation during graded submaximal exercise in women of different body composition

PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0242551
Author(s):  
Hugo A. Kerhervé ◽  
Leonie M. Harvey ◽  
Alexander N. Eagles ◽  
Chris McLellan ◽  
Dale Lovell
Keyword(s):  
Body Composition ◽  
Oxygen Uptake ◽  
Blood Lactate ◽  
Exercise Intensity ◽  
Perceived Exertion ◽  
Exercise Prescription ◽  
Fat Oxidation ◽  
Substrate Oxidation ◽  
Maximum Oxygen Uptake ◽  
Moderate Intensity

Background Moderate intensity exercise ranging 40–60% of maximum oxygen uptake is advised to promote energy expenditure and fat oxidation in overweight and obese people. Although fat oxidation has been shown to be highly variable among individual, there is still a relative uncertainty regarding exercise prescription for women specifically. This article aimed to determine whether indicators of body composition can be used to narrow the exercise intensity range for exercise prescription in women. Methods A total of 35 healthy women (age 30.8±9.5 yr) classified according to their BMI in normal weight (NOR; ≤24.9 kg·m2), overweight (OVW; 25–29.9 kg·m2) and obese groups (OBE; ≥30 kg·m2) completed a submaximal graded test (intensities eliciting ~30%, 40%, 50% and 60% of maximum oxygen uptake). Blood lactate, perceived exertion and absolute and relative substrate oxidation for fat (OXFAT) and carbohydrates (OXCHO) were measured at each stage. Results Perceived exertion and blood lactate increased as a function of exercise but did not differ across groups. There were no significant changes in absolute and relative OXFAT across groups, or as a function of exercise intensity. Peak OXFAT occurred at the 40%, 50% and 40% stages for NOR, OVW and OBE groups, respectively, with no significant differences across groups. Conclusion We measured no differences, but considerable inter-individual variation, in fat oxidation in women of different body composition. This result is in agreement with previous research based on exercise performed at constant rate and in independent participant groups. Our findings do not support the fat oxidation hypothesis, and further emphasise the perspective that exercise prescription should be individualised and likely be based on considerations other than substrate oxidation.

Respective oxidation of13C-labeled lactate and glucose ingested simultaneously during exercise

1997 ◽  
Vol 82 (2) ◽  
pp. 440-446 ◽  
Author(s):  
F. Péronnet ◽  
Y. Burelle ◽  
D. Massicotte ◽  
C. Lavoie ◽  
C. Hillaire-Marcel
Keyword(s):  
Oxygen Uptake ◽  
Plasma Glucose ◽  
Oxidation Rate ◽  
Prolonged Exercise ◽  
The Other ◽  
Energy Yield ◽  
Exogenous Glucose ◽  
Gastrointestinal Discomfort ◽  
Cumulative Amount ◽  
Male Subjects

Péronnet, F., Y. Burelle, D. Massicotte, C. Lavoie, and C. Hillaire-Marcel. Respective oxidation of13C-labeled lactate and glucose ingested simultaneously during exercise. J. Appl. Physiol. 82(2): 440–446, 1997.—The purpose of this experiment was to measure, by using13C labeling, the oxidation rate of exogenous lactate (25 g, as Na+, K+, Ca2+, and Mg2+ salts) and glucose (75 g) ingested simultaneously (in 1,000 ml of water) during prolonged exercise (120 min, 65 ± 3% maximum oxygen uptake in 6 male subjects). The percentage of exogenous glucose and lactate oxidized were similar (48 ± 3 vs. 45 ± 5%, respectively). However, because of the small amount of oral lactate that could be tolerated without gastrointestinal discomfort, the amount of exogenous lactate oxidized was much smaller than that of exogenous glucose (11.1 ± 0.5 vs. 36.3 ± 1.3 g, respectively) and contributed to only 2.6 ± 0.4% of the energy yield (vs. 8.4 ± 1.9% for exogenous glucose). The cumulative amount of exogenous glucose and lactate oxidized was similar to that observed when 100 g of [13C]glucose were ingested (47.3 ± 1.8 vs. 50.9 ± 1.2 g, respectively). When [13C]glucose was ingested, changes in the plasma glucose13C/12C ratio indicated that between 39 and 61% of plasma glucose derived from exogenous glucose. On the other hand, the plasma glucose13C/12C ratio remained unchanged when [13C]lactate was ingested, suggesting no prior conversion into glucose before oxidation.

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