Reversal of fatigue during prolonged exercise by carbohydrate infusion or ingestion

1987 ◽  
Vol 63 (6) ◽  
pp. 2388-2395 ◽  
Author(s):  
A. R. Coggan ◽  
E. F. Coyle
Keyword(s):  
Plasma Glucose ◽  
Prolonged Exercise ◽  
Respiratory Exchange Ratio ◽  
Vastus Lateralis ◽  
Exercise Bout ◽  
Glucose Infusion ◽  
Vastus Lateralis Muscle ◽  
Total Carbohydrate ◽  
Carbohydrate Ingestion ◽  
Placebo Trial

Seven cyclists exercised at 70% of maximal O2 uptake (VO2max) until fatigue (170 +/- 9 min) on three occasions, 1 wk apart. During these trials, plasma glucose declined from 5.0 +/- 0.1 to 3.1 +/- 0.1 mM (P less than 0.001) and respiratory exchange ratio (R) fell from 0.87 +/- 0.01 to 0.81 +/- 0.01 (P less than 0.001). After resting 20 min the subjects attempted to continue exercise either 1) after ingesting a placebo, 2) after ingesting glucose polymers (3 g/kg), or 3) when glucose was infused intravenously (“euglycemic clamp“). Placebo ingestion did not restore euglycemia or R. Plasma glucose increased (P less than 0.001) initially to approximately 5 mM and R rose (P less than 0.001) to approximately 0.83 with glucose infusion or carbohydrate ingestion. Plasma glucose and R then fell gradually to 3.9 +/- 0.3 mM and 0.81 +/- 0.01, respectively, after carbohydrate ingestion but were maintained at 5.1 +/- 0.1 mM and 0.83 +/- 0.01, respectively, by glucose infusion. Time to fatigue during this second exercise bout was significantly longer during the carbohydrate ingestion (26 +/- 4 min; P less than 0.05) or glucose infusion (43 +/- 5 min; P less than 0.01) trials compared with the placebo trial (10 +/- 1 min). Plasma insulin (approximately 10 microU/ml) and vastus lateralis muscle glycogen (approximately 40 mmol glucosyl U/kg) did not change during glucose infusion, with three-fourths of total carbohydrate oxidation during the second exercise bout accounted for by the euglycemic glucose infusion rate (1.13 +/- 0.08 g/min).(ABSTRACT TRUNCATED AT 250 WORDS)

Muscle glycogen oxidation during prolonged exercise measured with oral [13C]glucose: comparison with changes in muscle glycogen content

2007 ◽  
Vol 102 (5) ◽  
pp. 1773-1779 ◽  
Author(s):  
C. R. Harvey ◽  
R. Frew ◽  
D. Massicotte ◽  
F. Péronnet ◽  
N. J. Rehrer
Keyword(s):  
Plasma Glucose ◽  
Muscle Glycogen ◽  
Glucose Oxidation ◽  
Prolonged Exercise ◽  
Vastus Lateralis ◽  
Energy Yield ◽  
Vastus Lateralis Muscle ◽  
Tracer Technique ◽  
Total Carbohydrate ◽  
Tracer Techniques

Plasma glucose and muscle glycogen oxidation during prolonged exercise [75-min at 48 and 76% maximal O2 uptake (V̇o2 max)] were measured in eight well-trained male subjects [V̇o2 max = 4.50 l/min (SD 0.63)] using a simplified tracer technique in which a small amount of glucose highly enriched in 13C was ingested: plasma glucose oxidation was computed from 13C/12C in plasma glucose (which was stable beginning at minute 30 and minute 15 during exercise at 48 and 76% V̇o2 max, respectively) and 13CO2 production, and muscle glycogen oxidation was estimated by subtracting plasma glucose oxidation from total carbohydrate oxidation. Consistent data from the literature suggest that this small dose of exogenous glucose does not modify muscle glycogen oxidation and has little effect, if any, on plasma glucose oxidation. The percent contributions of plasma glucose and muscle glycogen oxidation to the energy yield at 48% V̇o2 max [15.1% (SD 3.8) and 45.9% (SD 5.8)] and at 76% V̇o2 max [15.4% (SD 3.6) and 59.8% (SD 9.2)] were well in line with data previously reported for similar work loads and exercise durations using conventional tracer techniques. The significant reduction in glycogen concentration measured from pre- and postexercise vastus lateralis muscle biopsies paralleled muscle glycogen oxidation calculated using the tracer technique and was larger at 76% than at 48% V̇o2 max. However, the correlation coefficients between these two estimates of muscle glycogen utilization were not different from zero at each of the two work loads. The simplified tracer technique used in the present experiment appears to be a valid alternative approach to the traditional tracer techniques for computing plasma glucose and muscle glycogen oxidation during prolonged exercise.

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.

Muscle metabolism during prolonged exercise in humans: influence of carbohydrate availability

1999 ◽  
Vol 87 (3) ◽  
pp. 1083-1086 ◽  
Author(s):  
G. McConell ◽  
R. J. Snow ◽  
J. Proietto ◽  
M. Hargreaves
Keyword(s):  
Oxygen Uptake ◽  
Vastus Lateralis ◽  
Time To Exhaustion ◽  
Endurance Capacity ◽  
Vastus Lateralis Muscle ◽  
Double Blind ◽  
Muscle Lactate ◽  
Carbohydrate Ingestion ◽  
Inosine Monophosphate ◽  
Muscle Energy

Eight endurance-trained men cycled to volitional exhaustion at 69 ± 1% peak oxygen uptake on two occasions to examine the effect of carbohydrate supplementation during exercise on muscle energy metabolism. Subjects ingested an 8% carbohydrate solution (CHO trial) or a sweet placebo (Con trial) in a double-blind, randomized order, with vastus lateralis muscle biopsies ( n = 7) obtained before and immediately after exercise. No differences in oxygen uptake, heart rate, or respiratory exchange ratio during exercise were observed between the trials. Exercise time to exhaustion was increased by ∼30% when carbohydrate was ingested [199 ± 21 vs. 152 ± 9 (SE) min, P < 0.05]. Plasma glucose and insulin levels during exercise were higher and plasma free fatty acids lower in the CHO trial. No differences between trials were observed in the decreases in muscle glycogen and phosphocreatine or the increases in muscle lactate due to exercise. Muscle ATP levels were not altered by exercise in either trial. There was a small but significant increase in muscle inosine monophosphate levels at the point of exhaustion in both trials, and despite the subjects in CHO trial cycling 47 min longer, their muscle inosine monophosphate level was significantly lower than in the Con trial (CHO: 0.16 ± 0.08, Con: 0.23 ± 0.09 mmol/kg dry muscle). These data suggest that carbohydrate ingestion may increase endurance capacity, at least in part, by improving muscle energy balance.

Fatigue and exhaustion in chronic hypobaric hypoxia: influence of exercising muscle mass

1994 ◽  
Vol 76 (2) ◽  
pp. 634-640 ◽  
Author(s):  
B. Kayser ◽  
M. Narici ◽  
T. Binzoni ◽  
B. Grassi ◽  
P. Cerretelli
Keyword(s):  
Hypobaric Hypoxia ◽  
Vastus Lateralis ◽  
Lactate Concentration ◽  
Exercise Bout ◽  
Vastus Lateralis Muscle ◽  
O2 Uptake ◽  
Before And After ◽  
Leg Exercise ◽  
Muscle Groups ◽  
Forearm Exercise

Exhaustive dynamic exercise with large muscle groups in chronic hypobaric hypoxia may be limited by central (nervous) rather than peripheral (metabolic) fatigue. Six males [32 +/- 4 (SD) yr] at sea level (SL) and after 1-mo acclimatization at 5,050 m (HA) performed exhaustive dynamic forearm exercise at a constant absolute load, requiring regional maximum aerobic power at SL, and exhaustive cycle exercise at prevailing maximal O2 uptake (HA approximately equal to 80% SL). Exhaustion time (t(ex)), blood O2 saturation (SaO2), and heart rate (HR) were measured during each exercise bout. Before and after both arm and leg exercise, lactate concentration ([La]), PO2, PCO2, and pH were measured in arterialized blood samples. Integrated electromyogram activity (IEMG) and mean (MPF) and centroid (CPF) power frequencies of the EMG power spectrum during exercise were calculated for forearm flexors and vastus lateralis muscle. t(ex) for forearm exercise at the same absolute load was the same at SL and HA. Similar increases of IEMG (+214% at SL vs. +172% at HA) and decreases of CPF (-13% at SL vs. -16% at HA) and MPF (-22% at SL vs. -21% at HA) were observed. By contrast, at HA, for similar t(ex), leg exercise had to be performed at the same relative (i.e., prevailing maximal O2 uptake) but lower absolute load (approximately equal to 80% of SL).(ABSTRACT TRUNCATED AT 250 WORDS)

Carbohydrate ingestion influences skeletal muscle cytokine mRNA and plasma cytokine levels after a 3-h run

2003 ◽  
Vol 94 (5) ◽  
pp. 1917-1925 ◽  
Author(s):  
D. C. Nieman ◽  
J. M. Davis ◽  
D. A. Henson ◽  
J. Walberg-Rankin ◽  
M. Shute ◽  
...  
Keyword(s):  
Gene Expression ◽  
Muscle Glycogen ◽  
Glycogen Content ◽  
Vastus Lateralis ◽  
Maximal Oxygen Consumption ◽  
Vastus Lateralis Muscle ◽  
Cytokine Mrna ◽  
Carbohydrate Ingestion ◽  
Muscle Glycogen Content ◽  
Tnf Α

Sixteen experienced marathoners ran on treadmills for 3 h at ∼70% maximal oxygen consumption (V˙o 2 max) on two occasions while receiving 1 l/h carbohydrate (CHO) or placebo (Pla) beverages. Blood and vastus lateralis muscle biopsy samples were collected before and after exercise. Plasma was analyzed for IL-6, IL-10, IL-1 receptor agonist (IL-1ra), IL-8, cortisol, glucose, and insulin. Muscle was analyzed for glycogen content and relative gene expression of 13 cytokines by using real-time quantitative RT-PCR. Plasma glucose and insulin were higher, and cortisol, IL-6, IL-10, and IL-1ra, but not IL-8, were significantly lower postexercise in CHO vs. Pla. Change in muscle glycogen content did not differ between CHO and Pla ( P = 0.246). Muscle cytokine mRNA content was detected preexercise for seven cytokines in this order (highest to lowest): IL-15, TNF-α, IL-8, IL-1β, IL-12p35, IL-6, and IFN-γ. After subjects ran for 3 h, gene expression above prerun levels was measured for five of these cytokines: IL-1β, IL-6, and IL-8 (large increases), and IL-10 and TNF-α (small increases). The increase in mRNA (fold difference from preexercise) was attenuated in CHO (15.9-fold) compared with Pla (35.2-fold) for IL-6 ( P = 0.071) and IL-8 (CHO, 7.8-fold; Pla, 23.3-fold; P = 0.063). CHO compared with Pla beverage ingestion attenuates the increase in plasma IL-6, IL-10, and IL-1ra and gene expression for IL-6 and IL-8 in athletes running 3 h at 70%V˙o 2 max despite no differences in muscle glycogen content.

scholarly journals Muscle metabolic, SR Ca2+-cycling responses to prolonged cycling, with and without glucose supplementation

2007 ◽  
Vol 103 (6) ◽  
pp. 1986-1998 ◽  
Author(s):  
T. A. Duhamel ◽  
H. J. Green ◽  
R. D. Stewart ◽  
K. P. Foley ◽  
I. C. Smith ◽  
...  
Keyword(s):  
Prolonged Exercise ◽  
Vastus Lateralis ◽  
Phase 1 ◽  
Vastus Lateralis Muscle ◽  
Release Rates ◽  
Oxidation Rates ◽  
Lateralis Muscle ◽  
Blood Glucose Homeostasis ◽  
Exercise Induced ◽  
Glucose Supplementation

This study investigated the effects of prolonged exercise, with and without glucose supplementation, on metabolism and sarcoplasmic reticulum (SR) Ca2+-handling properties in working vastus lateralis muscle. Fifteen untrained volunteers [peak O2consumption (V̇o2peak) = 3.45 ± 0.17 l/min; mean ± SE] cycled at ∼60% V̇o2peakon two occasions, during which they were provided with either an artificially sweetened placebo beverage (NG) or a 6% glucose (G) beverage (∼1.00 g carbohydrate/kg body mass). Beverage supplementation started at 30 min of exercise and continued every 15 min thereafter. SR Ca2+handling, metabolic, and substrate responses were assessed in tissue extracted from the vastus lateralis at rest, after 30 min and 90 min of exercise, and at fatigue in both conditions. Plasma glucose during G was 15–23% higher ( P < 0.05) than those observed during NG following 60 min of exercise until fatigue. Cycle time to fatigue was increased ( P < 0.05) by ∼19% during G (137 ± 7 min) compared with NG (115 ± 6 min). Prolonged exercise reduced ( P < 0.05) maximal Ca2+-ATPase activity (−18.4%), SR Ca2+uptake (−27%), and both Phase 1 (−22.2%) and Phase 2 (−34.2%) Ca2+-release rates during NG. The exercise-induced reductions in SR Ca2+-cycling properties were not altered during G. The metabolic responses to exercise were all unaltered by glucose supplementation, since no differences in respiratory exchange ratios, carbohydrate and lipid oxidation rates, and muscle metabolite and glycogen contents were observed between NG and G. These results indicate that the maintenance of blood glucose homeostasis by glucose supplementation is without effect in modifying the muscle metabolic, endogenous glycogen, or SR Ca2+-handling responses.

Influence of Exercise Mode and Carbohydrate on the Immune Response to Prolonged Exercise

1999 ◽  
Vol 9 (2) ◽  
pp. 213-228 ◽  
Author(s):  
Dru A. Henson ◽  
David C. Nieman ◽  
Andy D. Blodgett ◽  
Diane E. Butterworth ◽  
Alan Utter ◽  
...  
Keyword(s):  
Plasma Glucose ◽  
Lymphocyte Proliferation ◽  
Prolonged Exercise ◽  
Killer Cell ◽  
Lower Plasma ◽  
Hormonal Responses ◽  
Carbohydrate Ingestion ◽  
Exercise Mode ◽  
Mode Effects ◽  
Mode Effect

The influence of exercise mode and 6% carbohydrate (C) versus placebo (P) beverage ingestion on lymphocyte proliferation, natural killer cell cytotoxicily (NKCA), Interleukin (IL)-1ß production, and hormonal responses to 2.5 hr of intense running and cycling (~75% ) was measured in 10 triathletes serving as their own controls. The C versus P condition (but not exercise mode) resulted in higher plasma glucose concentrations, lower plasma cortisol concentrations, reduced poslexercise lymphocytosis and NKCA, and a lessened T-cell reduction during recovery. No condition or mode effects were observed for concanavalin A and phytohemagglutinin-induced lymphocyte proliferation. Significant mode (but not condition) effects were observed for lipopolysaccharide-induced IL-1ß production over time. However, when expressed per monocyte, the mode effect was abolished and a sustained suppression in IL-1 ß/monocyte was observed in all sessions throughout recovery. These data indicate that carbohydrate ingestion significantly affects plasma glucose and cortisol concentrations, blood lymphocyte counts, and NKCA, whereas exercise mode has no effect on these parameters.

Training-induced alterations in muscle glycogen utilization in fibre-specific types during prolonged exercise

1990 ◽  
Vol 68 (10) ◽  
pp. 1372-1376 ◽  
Author(s):  
H. J. Green ◽  
D. Smith ◽  
P. Murphy ◽  
I. Fraser
Keyword(s):  
Prolonged Exercise ◽  
Vastus Lateralis ◽  
Fibre Types ◽  
Vastus Lateralis Muscle ◽  
Type I ◽  
Glycogen Depletion ◽  
Recruitment Pattern ◽  
Intensive Training ◽  
Glycogen Concentration ◽  
The Face

Using the glycogen depletion technique, we have examined utilization of specific fibre types during prolonged submaximal exercise to investigate the recruitment pattern employed by the central nervous system to sustain force generation in the face of a progressive glycogen depletion. Six male subjects ([Formula: see text] max, 52.8 ± 2.5 mL∙kg−1∙min−1,[Formula: see text]) cycled at 59% of pretraining [Formula: see text] max (the same absolute power output) for 99.5 ± 6 min on two occasions, before training and after 10–12 days of intensive training, involving 2 h of cycling per day. Prior to the training, glycogen concentration during exercise in the type I and type IIA fibres of the vastus lateralis muscle as measured by microphotometric techniques was progressively reduced during exercise. The pattern of depletion in both of these fibre types was parallel and showed an early marked depletion amounting to 51 (p < 0.05) and 35% (p < 0.05) in the type I and type IIA fibres, respectively, during the first 15 min of exercise. At the end of exercise, glycogen levels in type I and type IIA fibres were reduced to 9 and 44% of initial levels, respectively. In contrast, glycogen concentration in type IIB fibres was not significantly (p < 0.05) altered throughout the exercise. Following training, a pronounced glycogen sparing occurred that was conspicuous in only the type I and type IIA fibres, which was most pronounced during the first 15 min of the exercise. Similar to pretraining, glycogen concentrations in type IIB fibres were unaffected by either exercise or training. These results support the hypothesis that the muscle fibre recruitment patterns are established early in exercise and that even in the face of extensive glycogen loss observed late in exercise in the lower threshold type I and type IIA fibres, the higher threshold type IIB fibres are not recruited.Key words: recruitment, fibre types (I, IIA, and IIB), prolonged exercise, glycogen depletion.

scholarly journals The rate of substrate cycling between fructose 6-phosphate and fructose 1,6-bisphosphate in skeletal muscle from cold-exposed, hyperthyroid or acutely exercised rats

1985 ◽  
Vol 231 (1) ◽  
pp. 217-220 ◽  
Author(s):  
R A J Challis ◽  
J R S Arch ◽  
E A Newsholme
Keyword(s):  
Cold Exposure ◽  
Acute Exercise ◽  
Vastus Lateralis ◽  
Exercise Bout ◽  
Vastus Lateralis Muscle ◽  
Hyperthyroid State ◽  
Fructose 1,6 Bisphosphatase ◽  
Fructose 1,6 Bisphosphate

The effects of cold-exposure, the hyperthyroid state and a single exercise bout in vivo on the maximal enzyme activities of 6-phosphofructokinase and fructose-1,6-bisphosphatase in vastus lateralis muscle and the rates of fructose 6-phosphate/fructose 1,6-bisphosphate cycling measured in epitrochlearis muscle in vitro were investigated. In all cases significant changes in substrate cycling rates were observed, whether in the absence of added hormones in vitro (acute exercise), or when stimulated by insulin plus adrenaline (cold-exposure), or with respect to the catecholamine-sensitivity of the cycling rate (the hyperthyroid state).

Glucose supplements increase human muscle in vitro Na+-K+-ATPase activity during prolonged exercise

2007 ◽  
Vol 293 (1) ◽  
pp. R354-R362 ◽  
Author(s):  
H. J. Green ◽  
T. A. Duhamel ◽  
K. P. Foley ◽  
J. Ouyang ◽  
I. C. Smith ◽  
...  
Keyword(s):  
Atpase Activity ◽  
Prolonged Exercise ◽  
Serum Insulin ◽  
Vastus Lateralis ◽  
Oral Glucose ◽  
Vastus Lateralis Muscle ◽  
Ouabain Binding ◽  
Similar Time ◽  
Phosphatase Assay

Regulation of maximal Na+-K+-ATPase activity in vastus lateralis muscle was investigated in response to prolonged exercise with (G) and without (NG) oral glucose supplements. Fifteen untrained volunteers (14 males and 1 female) with a peak aerobic power (V̇o2peak) of 44.8 ± 1.9 ml·kg−1·min−1; mean ± SE cycled at ∼57% V̇o2peak to fatigue during both NG (artificial sweeteners) and G (6.13 ± 0.09% glucose) in randomized order. Consumption of beverage began at 30 min and continued every 15 min until fatigue. Time to fatigue was increased ( P < 0.05) in G compared with NG (137 ± 7 vs. 115 ± 6 min). Maximal Na+-K+-ATPase activity (Vmax) as measured by the 3- O-methylfluorescein phosphatase assay (nmol·mg−1·h−1) was not different between conditions prior to exercise (85.2 ± 3.3 or 86.0 ± 3.9), at 30 min (91.4 ± 4.7 vs. 91.9 ± 4.1) and at fatigue (92.8 ± 4.3 vs. 100 ± 5.0) but was higher ( P < 0.05) in G at 90 min (86.7 ± 4.2 vs. 109 ± 4.1). Na+-K+-ATPase content (βmax) measured by the vanadate facilitated [3H]ouabain-binding technique (pmol/g wet wt) although elevated ( P < 0.05) by exercise (0<30, 90, and fatigue) was not different between NG and G. At 60 and 90 min of exercise, blood glucose was higher ( P < 0.05) in G compared with NG. The G condition also resulted in higher ( P < 0.05) serum insulin at similar time points to glucose and lower ( P < 0.05) plasma epinephrine and norepinephrine at 90 min of exercise and at fatigue. These results suggest that G results in an increase in Vmax by mechanisms that are unclear.

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