Glycogen resynthesis in leg muscles of rats during exercise

1984 ◽  
Vol 247 (5) ◽  
pp. R880-R883 ◽  
Author(s):  
S. H. Constable ◽  
J. C. Young ◽  
M. Higuchi ◽  
J. O. Holloszy
Keyword(s):  
Muscle Glycogen ◽  
Prolonged Exercise ◽  
Liver Glycogen ◽  
Treadmill Running ◽  
Moderate Intensity ◽  
Glycogen Depletion ◽  
Moderate Intensity Exercise ◽  
Glycogen Resynthesis ◽  
Leg Muscles ◽  
Insulin In Plasma

This study was undertaken to determine whether glycogen resynthesis can occur in glycogen-depleted muscles in response to glucose feeding during prolonged exercise. Rats were exercised for 40 min with a treadmill running program designed to deplete muscle glycogen. One group was studied immediately after the glycogen-depletion exercise. A second group was given 1 g glucose by stomach tube and exercised for an additional 90 min at a running speed of 22 m/min on a treadmill set at an 8 degree incline; they were given additional 1-g glucose feedings after 30 and 60 min of running. The initial 40-min run resulted in liver glycogen depletion, large decreases in plasma glucose and insulin concentrations, and a marked lowering of muscle glycogen. The glucose feedings resulted in greater than twofold increases in the concentrations of glucose and insulin in plasma, and of glycogen in leg muscles, during the 90 min of running. No repletion of liver glycogen occurred. These results provide evidence that glycogen resynthesis can occur in glycogen-depleted muscle despite continued moderate intensity exercise if sufficient glucose is made available.

scholarly journals Beetroot juice ingestion during prolonged moderate-intensity exercise attenuates progressive rise in O2 uptake

2018 ◽  
Vol 124 (5) ◽  
pp. 1254-1263 ◽  
Author(s):  
Rachel Tan ◽  
Lee J. Wylie ◽  
Christopher Thompson ◽  
Jamie R. Blackwell ◽  
Stephen J. Bailey ◽  
...  
Keyword(s):  
Muscle Glycogen ◽  
Exercise Bout ◽  
Moderate Intensity ◽  
Beetroot Juice ◽  
Elevated Plasma ◽  
Glycogen Depletion ◽  
Moderate Intensity Exercise ◽  
Double Blind ◽  
Plasma Nitrite ◽  
Over Time

Nitrate-rich beetroot juice (BR) supplementation has been shown to increase biomarkers of nitric oxide availability with implications for the physiological responses to exercise. We hypothesized that BR supplementation before and during prolonged moderate-intensity exercise would maintain an elevated plasma nitrite concentration ([[Formula: see text]]), attenuate the expected progressive increase in V̇o2 over time, and improve performance in a subsequent time trial (TT). In a double-blind, randomized, crossover design, 12 men completed 2 h of moderate-intensity cycle exercise followed by a 100-kJ TT in three conditions: 1) BR before and 1 h into exercise (BR + BR); 2) BR before and placebo (PL) 1 h into exercise (BR + PL); and 3) PL before and 1 h into exercise (PL + PL). During the 2-h moderate-intensity exercise bout, plasma [[Formula: see text]] declined by ~17% in BR + PL but increased by ~8% in BR + BR such that, at 2 h, plasma [[Formula: see text]] was greater in BR + BR than both BR + PL and PL + PL ( P < 0.05). V̇o2 was not different among conditions over the first 90 min of exercise but was lower at 120 min in BR + BR (1.73 ± 0.24 l/min) compared with BR + PL (1.80 ± 0.21 l/min; P = 0.08) and PL + PL (1.83 ± 0.27 l/min; P < 0.01). The decline in muscle glycogen concentration over the 2-h exercise bout was attenuated in BR + BR (~28% decline) compared with BR + PL (~44% decline) and PL + PL (~44% decline; n = 9, P < 0.05). TT performance was not different among conditions ( P > 0.05). BR supplementation before and during prolonged moderate-intensity exercise attenuated the progressive rise in V̇o2 over time and appeared to reduce muscle glycogen depletion but did not enhance subsequent TT performance. NEW & NOTEWORTHY We show for the first time that ingestion of nitrate during exercise preserves elevated plasma [nitrite] and negates the progressive rise in O2 uptake during prolonged moderate-intensity exercise.

Oral acetate supplementation after prolonged moderate intensity exercise enhances early muscle glycogen resynthesis in horses

2009 ◽  
Vol 94 (8) ◽  
pp. 888-898 ◽  
Author(s):  
Amanda P. Waller ◽  
Raymond J. Geor ◽  
Lawrence L. Spriet ◽  
George J. F. Heigenhauser ◽  
Michael I. Lindinger
Keyword(s):  
Muscle Glycogen ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Glycogen Resynthesis

Fluid and electrolyte supplementation after prolonged moderate-intensity exercise enhances muscle glycogen resynthesis in Standardbred horses

2009 ◽  
Vol 106 (1) ◽  
pp. 91-100 ◽  
Author(s):  
Amanda P. Waller ◽  
George J. F. Heigenhauser ◽  
Raymond J. Geor ◽  
Lawrence L. Spriet ◽  
Michael I. Lindinger
Keyword(s):  
Electrolyte Solution ◽  
Muscle Glycogen ◽  
Venous Blood ◽  
Recovery Period ◽  
Plasma Osmolality ◽  
Whole Body ◽  
Control Treatment ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Glycogen Resynthesis

We hypothesized that postexercise rehydration using a hypotonic electrolyte solution will increase the rate of recovery of whole body hydration, and that this is associated with increased muscle glycogen and electrolyte recovery in horses. Gluteus medius biopsies and jugular venous blood were sampled from six exercise-conditioned Standardbreds on two separate occasions, at rest and for 24 h following a competitive exercise test (CET) designed to simulate the speed and endurance test of a 3-day event. After the CETs, horses were given water ad libitum, and either a hypotonic commercial electrolyte solution (electrolyte) via nasogastric tube, followed by a typical hay/grain meal, or a hay/grain meal alone (control). The CET resulted in decreased total body water and muscle glycogen concentration of 8.4 ± 0.3 liters and 22.6%, respectively, in the control treatment, and 8.2 ± 0.4 liters and 21.9% in the electrolyte treatment. Electrolyte resulted in an enhanced rate of muscle glycogen resynthesis and faster restoration of hydration (as evidenced by faster recovery of plasma protein concentration, maintenance of plasma osmolality, and greater muscle intracellular fluid volume) during the recovery period compared with control. There were no differences in muscle Na, K, Cl, or Mg contents between the two treatments. It is concluded that oral administration of a hypotonic electrolyte solution after prolonged moderate-intensity exercise enhanced the rate of muscle glycogen resynthesis during the recovery period compared with control. It is speculated that postexercise dehydration may be one key contributor to the slow muscle glycogen replenishment in horses.

Effects of maternal exercise on liver and skeletal muscle glycogen storage in pregnant rats

1991 ◽  
Vol 71 (3) ◽  
pp. 1015-1019 ◽  
Author(s):  
M. F. Mottola ◽  
P. D. Christopher
Keyword(s):  
Skeletal Muscle ◽  
Muscle Glycogen ◽  
Glycogen Content ◽  
Liver Glycogen ◽  
Glycogen Storage ◽  
Treadmill Running ◽  
Control Group ◽  
Skeletal Muscle Glycogen ◽  
Maternal Exercise ◽  
White Gastrocnemius

To examine the effects of maternal exercise on liver and skeletal muscle glycogen storage, female Sprague-Dawley rats were randomly divided into control, nonpregnant runner, pregnant nonrunning control, pregnant runner, and prepregnant exercised control groups. The exercise consisted of treadmill running at 30 m/min on a 10 degree incline for 60 min, 5 days/wk. Pregnancy alone, on day 20 of gestation, decreased maternal liver glycogen content and increased red and white gastrocnemius muscle glycogen storage above control values (P less than 0.05). In contrast, exercise in nonpregnant animals augmented liver glycogen storage and also increased red and white gastrocnemius glycogen content (P less than 0.05). By combining exercise and pregnancy, the decrease in liver glycogen storage in the pregnant nonexercised condition was prevented in the pregnant runner group and more glycogen was stored in both the red and white portions of the gastrocnemius than all other groups (P less than 0.05). Fetal body weight was greatest (P less than 0.05) in the pregnant runner group and lowest (P less than 0.05) in the prepregnant exercise control group. These results demonstrate that chronic maternal exercise may change maternal glycogen storage patterns in the liver and skeletal muscle with some alteration in fetal outcome.

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.

Progressive increase in human skeletal muscle AMPKα2 activity and ACC phosphorylation during exercise

2002 ◽  
Vol 282 (3) ◽  
pp. E688-E694 ◽  
Author(s):  
T. J. Stephens ◽  
Z.-P. Chen ◽  
B. J. Canny ◽  
B. J. Michell ◽  
B. E. Kemp ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Glycogen ◽  
Human Skeletal Muscle ◽  
Glycogen Content ◽  
Vastus Lateralis ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Western Blots ◽  
Muscle Glycogen Content ◽  
Muscle Creatine

The effect of prolonged moderate-intensity exercise on human skeletal muscle AMP-activated protein kinase (AMPK)α1 and -α2 activity and acetyl-CoA carboxylase (ACCβ) and neuronal nitric oxide synthase (nNOSμ) phosphorylation was investigated. Seven active healthy individuals cycled for 30 min at a workload requiring 62.8 ± 1.3% of peak O2consumption (V˙o 2 peak) with muscle biopsies obtained from the vastus lateralis at rest and at 5 and 30 min of exercise. AMPKα1 activity was not altered by exercise; however, AMPKα2 activity was significantly ( P < 0.05) elevated after 5 min (∼2-fold), and further elevated ( P < 0.05) after 30 min (∼3-fold) of exercise. ACCβ phosphorylation was increased ( P < 0.05) after 5 min (∼18-fold compared with rest) and increased ( P< 0.05) further after 30 min of exercise (∼36-fold compared with rest). Increases in AMPKα2 activity were significantly correlated with both increases in ACCβ phosphorylation and reductions in muscle glycogen content. Fat oxidation tended ( P = 0.058) to increase progressively during exercise. Muscle creatine phosphate was lower ( P < 0.05), and muscle creatine, calculated free AMP, and free AMP-to-ATP ratio were higher ( P < 0.05) at both 5 and 30 min of exercise compared with those at rest. At 30 min of exercise, the values of these metabolites were not significantly different from those at 5 min of exercise. Phosphorylation of nNOSμ was variable, and despite the mean doubling with exercise, statistically significance was not achieved ( P = 0.304). Western blots indicated that AMPKα2 was associated with both nNOSμ and ACCβ consistent with them both being substrates of AMPKα2 in vivo. In conclusion, AMPKα2 activity and ACCβ phosphorylation increase progressively during moderate exercise at ∼60% of V˙o 2 peak in humans, with these responses more closely coupled to muscle glycogen content than muscle AMP/ATP ratio.

Muscle Glycogen Restoration In Trained Female And Male Cyclists Following Moderate Intensity Exercise

2004 ◽  
Vol 36 (Supplement) ◽  
pp. S18
Author(s):  
Michael J. Carper ◽  
Samantha A. Whitman ◽  
Scott R. Richmond ◽  
Luke S. Acree ◽  
Brett D. Olson ◽  
...  
Keyword(s):  
Muscle Glycogen ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise

scholarly journals Muscle glycogen and metabolic regulation

2004 ◽  
Vol 63 (2) ◽  
pp. 217-220 ◽  
Author(s):  
Mark Hargreaves
Keyword(s):  
Muscle Glycogen ◽  
Insulin Action ◽  
Metabolic Regulation ◽  
Strenuous Exercise ◽  
Glycogen Depletion ◽  
Excitation Contraction Coupling ◽  
Glycogen Resynthesis ◽  
Contraction Coupling ◽  
Cellular Processes ◽  
Exercise Induced

Muscle glycogen is an important fuel for contracting skeletal muscle during prolonged strenuous exercise, and glycogen depletion has been implicated in muscle fatigue. It is also apparent that glycogen availability can exert important effects on a range of metabolic and cellular processes. These processes include carbohydrate, fat and protein metabolism during exercise, post-exercise glycogen resynthesis, excitation–contraction coupling, insulin action and gene transcription. For example, low muscle glycogen is associated with reduced muscle glycogenolysis, increased glucose and NEFA uptake and protein degradation, accelerated glycogen resynthesis, impaired excitation–contraction coupling, enhanced insulin action and potentiation of the exercise-induced increases in transcription of metabolic genes. Future studies should identify the mechanisms underlying, and the functional importance of, the association between glycogen availability and these processes.

Lipid peroxidation and scavenger enzymes during exercise: adaptive response to training

1988 ◽  
Vol 64 (4) ◽  
pp. 1333-1336 ◽  
Author(s):  
H. M. Alessio ◽  
A. H. Goldfarb
Keyword(s):  
Lipid Peroxidation ◽  
Endurance Training ◽  
Acute Exercise ◽  
Oxidative Capacity ◽  
Treadmill Running ◽  
Moderate Intensity ◽  
Sprague Dawley ◽  
Moderate Intensity Exercise ◽  
Sod Activity ◽  
Sprague Dawley Rats

This study was designed to determine whether endurance training would influence the production of lipid peroxidation (LI-POX) by-products as indicated by malondialdehyde (MDA) at rest and after an acute exercise run. Additionally, the scavenger enzymes catalase (CAT) and superoxide dismutase (SOD) were examined to determine whether changes in LIPOX are associated with alterations in enzyme activity both at rest and after exercise. Male Sprague-Dawley rats (n = 32) were randomly assigned to either trained or sedentary groups and were killed either at rest or after 20 min of treadmill running. The training program increased oxidative capacity 64% in leg muscle. After exercise, the sedentary group demonstrated increased LIPOX levels in liver and white skeletal muscle, whereas the endurance-trained group did not show increases in LIPOX after exercise. CAT activity was higher in both red and white muscle after exercise in the trained animals. Total SOD activity was unaffected by either acute or chronic exercise. These data suggest that endurance training can result in a reduction in LIPOX levels as indicated by MDA during moderate-intensity exercise. It is possible that activation of the enzyme catalase and the increase in respiratory capacity were contributory factors responsible for regulating LIPOX after training during exercise.

Physical Activity, Exercise, and the Immune System: Three Lines of Research That Have Driven the Field

2015 ◽  
Vol 4 (1) ◽  
pp. 118-125
Author(s):  
Jeffrey A. Woods ◽  
Brandt D. Pence
Keyword(s):  
Immune System ◽  
Immune Function ◽  
Acute Exercise ◽  
Prolonged Exercise ◽  
Moderate Intensity ◽  
Upper Respiratory Tract ◽  
Moderate Intensity Exercise ◽  
Exercise Immunology ◽  
Upper Respiratory ◽  
Exercise Induced

Exercise immunology is a relatively new discipline in the exercise sciences that seeks to understand how exercise affects the immune system and susceptibility to infectious and chronic diseases. This brief review will focus on three major observations that have driven the field to date including: (1) acute exercise-induced leukocytosis, (2) the observation that intense, prolonged exercise results in upper respiratory tract symptoms, and (3) the paradoxical effect of acute and chronic exercise on inflammation. This framework will be used to examine the mechanisms and implications behind these seminal observations. Data generally support the conclusion that moderate intensity exercise enhances immune function, whereas prolonged, intense exercise diminishes immune function.

Sign in / Sign up

Export Citation Format

Share Document