Update on Carbohydrate: Solid versus Liquid

1994 ◽  
Vol 4 (2) ◽  
pp. 80-88 ◽  
Author(s):  
Ellen Coleman

Athletes often train or compete in athletic events that significantly reduce muscle and liver glycogen reserves. Carbohydrate ingestion before or during endurance exercise enhances performance by maintaining blood glucose levels and carbohydrate utilization. Also, an adequate intake of carbohydrate following endurance exercise helps to restore muscle and liver glycogen. This paper reviews the physiologic and performance benefits of solid versus liquid carbohydrate feedings before, during, and following endurance exercise. Solid and liquid carbohydrates are equally effective in raising blood glucose and enhancing performance when consumed during endurance exercise. Also, both forms of carbohydrate are similarly beneficial in promoting muscle glycogen synthesis after exercise. It is unclear whether solid and liquid carbohydrate feedings have the same effect on serum glucose and performance when consumed before exercise. Although limited research suggests that a low glycemic solid carbohydrate may represent the best preexercise meal choice, further research is needed to support this hypothesis.

Author(s):  
Kenia Mendes Rodrigues Castro ◽  
Rodrigo Leal de Paiva Carvalho ◽  
Geraldo Marco Rosa Junior ◽  
Beatriz Antoniassi Tavares ◽  
Luis Henrique Simionato ◽  
...  

1974 ◽  
Vol 61 (2) ◽  
pp. 171-177 ◽  
Author(s):  
J. J. GAGLIARDINO ◽  
MARÍA TERESA PESSACQ

SUMMARY The effect of a single dose of insulin i.u./kg, i.p.) injected every 4 h during a 24-h period was studied in normal mice. The glycogen content of the diaphragm muscle and serum glucose levels were determined every 15 min throughout a period of 60 min after the hormone injection. Although insulin always produced an increase in glycogen and a decline in serum glucose, neither the sequential changes observed during the 60 min after injection nor the magnitude of these changes were constant throughout the 24 h of the day. The two circadian variations in the action of insulin (on glycogen and glucose) did not display any well-defined relationship, i.e. the most marked decline in glucose was not followed by a correspondingly marked increase in glycogen. These observations suggest that the results obtained from the administration of a single dose of insulin at an arbitrary time of day might be misleading. The circadian variations found could represent another component of the complex homeostatic mechanisms in which insulin is involved.


1981 ◽  
Vol 50 (1) ◽  
pp. 94-101 ◽  
Author(s):  
S. E. Terblanche ◽  
R. D. Fell ◽  
A. C. Juhlin-Dannfelt ◽  
B. W. Craig ◽  
J. O. Holloszy

Rats were fed either 1 g of glycerol or 1 g of glucose following exercise to exhaustion. Glucose feeding resulted in a rapid increase in blood glucose, with attainment of peak hyperglycemia within 1 h and of peak muscle glycogen in about 2 h. Feeding 1 g of glycerol resulted in marked elevation of glycerol concentration in blood, liver, and muscle; the highest values, measured 1 h after glycerol feeding, ranged from 29 to 42 mumol/g tissue. Blood glucose and muscle glycogen increased slowly in the glycerol-fed rats and peaked much later than after glucose feeding. In perfused rat hindlimb muscles, negligible amounts of [14C]glycerol were incorporated into glycogen. These findings suggest that muscle is not able to utilize glycerol to a significant extent and that glucose derived from glycerol was the major substrate for muscle glycogen synthesis. Animals fed glycerol before a run to exhaustion were able to exercise significantly longer than control rats (153 +/- 11 min vs. 116 +/- 6 min). The glycerol-fed rats depleted their muscle and liver glycogen stores less rapidly than the controls and were protected against development of hypoglycemia during the exercise.


1964 ◽  
Vol 207 (2) ◽  
pp. 411-414 ◽  
Author(s):  
Jiro Oyama ◽  
William T. Platt

Unrestrained mice were centrifuged for varying periods ranging from 0.5 to 10 hr at 2.5, 5, and 10 x gravity. Liver glycogen and blood glucose levels increased significantly depending on the g load and exposure time. Adrenalectomy completely abolished the glycogen deposition response. The glycogen response was a critical function of the age of mice; unweaned mice did not respond. Blood corticosterone increased significantly prior to the deposition of glycogen. Centrifuged fed mice deposited three times the amount of glycogen of fasted mice. There was no significant difference in the amount of glycogen deposited in centrifuged mice previously starved for 1, 2, or 3 days. It is concluded that the increased glycogen deposited following centrifugation is effected by an increased elaboration of adrenal corticosterone.


Author(s):  
Ricardo LÓPEZ-SOLÍS ◽  
Brenda Hildeliza CAMACHO-DÍAZ ◽  
Roberto CAMPOS-MENDIOLA ◽  
María Araceli ORTÍZ-RODRÍGUEZ

The aim of this review is to summarize the effects of carbohydrate consumption on endurance sports. Due to the promotion of physical activity by health authorities, participation in endurance sports is increasing. Regardless of the level, athletes look for ways to optimize their performance through training and nutrition. In consequence, research in the field of sports nutrition has focused on those strategies that can improve performance. Fatigue during prolonged exercise is associated with depletion of muscle glycogen and reduced blood glucose concentrations. Therefore, carbohydrate feeding during exercise has shown that it can improve capacity and performance, because it helps maintain blood glucose levels, as well as, increase carbohydrate oxidation rates and preserve glycogen, finding better results when are consumed multiple-tranportable carbohydrates for absortion (e.g., fructose and glucose), since in this way is possible to increase absorption rates, gastric emptying and fluid absorption, in addition to decrease gastrointestinal distress.


PEDIATRICS ◽  
1963 ◽  
Vol 32 (6) ◽  
pp. 1002-1006
Author(s):  
Donnell D. Etzwiler

Glucagon or a placebo preparation was administered to 65 juvenile diabetics on 74 separate occasions. When the initial blood glucose of these children showed them to be in reasonably good control, glucagon produced a hyperglycemic effect. However, when the blood glucose levels were markedly elevated, the effect of glucagon was less predictable. The depletion of liver glycogen stores and the possible effect of contaminating insulin in glucagon preparations are discussed.


1982 ◽  
Vol 243 (1) ◽  
pp. R179-R184 ◽  
Author(s):  
W. W. Winder ◽  
M. A. Beattie ◽  
R. T. Holman

Endurance exercise training produces major adaptations in hormonal and metabolic responses to exercise. This study was designed to determine whether the differences in hormone response persist in the fasted condition when liver glycogen is depleted. Rats were run on a motor-driven rodent treadmill 5 days/wk for periods up to 2 h/day for 10 wk. Trained and nontrained rats were then fasted 24 h and were run for periods ranging from 0- to 60 min. At the end of 60 min of exercise muscle glycogen was higher in trained rats (2.9 +/- 0.3 vs. 1.1 +/- 0.1 mg/g). Blood glucose was maintained at higher levels in trained rats throughout the course of the exercise (3.2 +/- 0.1 vs. 2.3 +/- 0.1 mM after 60 min). Plasma concentrations of glucagon and epinephrine increased in both groups during the exercise but were significantly lower in trained animals. Differences between trained and nontrained animals in stress hormone responses to exercise persist in the fasted state and appear to be a consequence of the capacity of trained animals to maintain higher blood glucose levels.


2019 ◽  
Vol 2019 ◽  
pp. 1-4 ◽  
Author(s):  
George A. Alexiou ◽  
Athanasios Sotiropoulos ◽  
Georgios D. Lianos ◽  
Andreas Zigouris ◽  
Dimitrios Metaxas ◽  
...  

Traumatic brain injury has been associated with increased blood glucose levels. In the present study, we set out to investigate if blood glucose level in mild head trauma could predict the need for CT. One hundred fifty-nine patients with minor TBI (GCS 13-15) and a mean age of44.8±23.8years were included in the study. The most common mechanism of trauma was falls. Patients with positive CT findings had significantly higher glucose levels than patients with negative CT findings. Using ROC curve analysis, serum glucose levels higher than 120 mg dl-1were the optimal cutoff value for the detection of patients with positive CT findings with a sensitivity of 74.4% and a specificity of 90.7%. Serum glucose level evaluation at presentation in the emergency department may aid CT decision-making in mild TBI.


1982 ◽  
Vol 243 (3) ◽  
pp. R450-R453
Author(s):  
W. Langhans ◽  
N. Geary ◽  
E. Scharrer

The effects of feeding on liver glycogen content and blood glucose in the hepatic and hepatic portal veins were investigated in rats. Liver glycogen content decreased about 25% during meals both in rats refed after 12 h food deprivation (23 +/- 1 to 17 +/- 1 mg glycogen/g liver) and in ad libitum-fed rats taking fully spontaneous meals (44 +/- 2 to 32 +/- 2 mg/g). Liver glycogen began to increase within 30 min after meals in ad libitum-fed rats. Hepatic vein blood glucose levels at meal onset (118 +/- 4 mg/dl in the food-deprived rats, 127 +/- 4 in ad libitum-fed rats) and at meal end (155 +/- 3 and 166 +/- 5 mg/dl, respectively) were similar in the two groups. Portal vein blood glucose increased during meals in the previously food-deprived rats (83 +/- 4 to 116 +/- 6 mg/dl) but not in the ad libitum-fed rats (127 +/- 5 to 132 +/- 3 mg/dl). Mechanisms that may elicit prandial glycogenolysis and the possible role of this effect in the production of meal ending satiety are discussed.


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