Evaluation of muscle tissue and liver glycogen of cattle submitted to transport over long distances and subjected to emergency slaughter / Avaliação do tecido muscular e glicogênio hepático de bovinos transportados por longas distâncias e submetidos ao abate de emergência

The study evaluated the effect of transportation over long distances on cattle muscle tissue of submitted to emergency slaughter in slaughterhouses in northern Tocantins, Brazil. The evaluations consisted in pH, muscle and liver glycogen, muscle histopathology and creatine kinase (CK), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activity. Animals were placed into two groups: Experimental Group (EG), consisting of 19 bovines intended for immediate emergency slaughter, and Control Group (CG), composed of 24 bovines slaughtered in accordance with the normal flow. CK and ALT levels were high in EG. AST did not differ between groups. EG showed higher muscle pH and mean of degenerate fibers, mainly on the intercostal. However, muscle and liver glycogen did not differ between groups. In conclusion, cattle transported over long distances and subjected to immediate emergency slaughter showed markedly stress condition, with changes in biochemical parameters in the muscle tissue, determined by cellular degeneration.(AU)

O presente trabalho objetivou avaliar o efeito do transporte em longas distâncias sobre o tecido muscular de bovinos encaminhados ao abate de emergência. Foram avaliados pH, glicogênio muscular e hepático, análise histopatológica muscular, creatina quinase (CK), alanina aminotransferase (ALT) e aspartato aminotransferase (AST). Os animais foram alocados em dois grupos: grupo experimental (GE), constituído por 19 bovinos destinados ao abate de emergência, e grupo controle (GC), composto por 24 bovinos abatidos de acordo com o fluxo normal do frigorífico. A CK e a ALT estavam aumentadas no GE. O AST não diferiu entre os grupos. O GE apresentou maior percentual de fibras degeneradas, e o músculo intercostal teve maior quantidade de degenerações. O pH muscular foi superior no GE. O glicogênio muscular e o hepático não diferiram entre os grupos. Concluiu-se que bovinos encaminhados ao abate de emergência sofrem estresse severo pelo transporte por longas distâncias, com alterações bioquímicas no tecido muscular determinada pela degeneração celular.(AU)

Traditional models of fatigue and physical performance / Modelos tradicionais de fadiga e desempenho físico

ABSTRACT The origin of fatigue has been the focus of studies involved in sports performance, due to the necessity to clarify the mechanistic bases for the reduced capacity to perform considerable effort intensities. According to the traditional conception of fatigue, mechanisms may encompass peripheral and central sites of fatigue. Peripheral fatigue is understood as events related to an inefficient tissue oxygen delivery, metabolic accumulation, muscular acidosis and muscle substrate depletion. In contrast, the central fatigue is mostly related to events in the central nervous system (CNS) that may involve neurotransmitters changes, altered metabolic profile and elevated temperature. Therefore, the current review aimed to discuss the peripheral and central mechanisms of fatigue, thus driving interpretations of the phenomenon.

RESUMO A etiologia da fadiga tem sido objeto de estudo em pesquisas relacionadas ao desempenho esportivo em função da necessidade de esclarecer os mecanismos que reduzem a capacidade de manutenção do desempenho em intensidades elevadas de esforço. A concepção tradicional de fadiga assume que os mecanismos possam ser desencadeados em sítios de ação central ou periférica. A fadiga periférica é compreendida como uma oferta inadequada de oxigênio tecidual, acúmulo de metabólitos e depleção de substrato energético acelerando a acidose muscular. A fadiga central, por sua vez, oriunda do sistema nervoso central (SNC), apresenta alterações nos neurotransmissores, podendo alterar o perfil metabólico e temperatura do SNC. Desta forma, a presente revisão tem como intuito abordar os mecanismos de fadiga central e periférica, norteando futuras interpretações sobre o fenômeno.

Effects of Aerobic Exercise on Skeletal Muscle Glycogen and Exercise Endurance in Rats with Chronic Heart Failure / 中国康复理论与实践

@#Objective To observe the effects of 8-week aerobic exercise on skeletal muscle glycogen content and exercise endurance and investigate the possible mechanism in rats with chronic heart failure. Methods 30 Sprague-Dawley rats were submitted to heart failure sedentary (H) group, heart failure traning (HT) group and sham operation (S) group. The heart failure model was established with coronary artery ligation. HT group performed an 8-week treadmill running. The skeletal muscle glycogen content was determined with anthracenone, exercise endurance with exhaust duration of graded exhausted exercise test, glucose uptake rate, activity of glycogen synthase (GS) and glycogen phosphorylase (GP) with radicisotope, protein expression of total GS, phospho-GS (p-GS), total GP and phospho-GP (p-GP) with Western Blotting. Correlation analysis was conducted between glycogen content and exhaust duration. Results The skeletal muscle glycogen, exhaust duration, glucose uptake rate, GS activity and p-GP protein reduced (P<0.05), while serum insulin, GP activity and p-GS protein raised (P<0.05) in the H group compared with those in the S group. The skeletal muscle glycogen, exhaust duration, glucose uptake rate, GS activity and p-GP protein increased (P<0.05), while serum insulin, GP activity and p-GS protein decreased (P<0.05) in the HT group compared with those in the H group. There was positive correlation between glycogen content and exhaust duration (P<0.05). Conclusion Prolonged aerobic exercise enhanced skeletal muscle glycogen content and exercise endurance in rats with chronic heart failure, which may be related to the improvement of insulin sensitivity, muscle glucose uptake, increase of glycogen synthesis and decrease of glycogen breakdown.

Effects of prior muscle glycogen depletion level on metabolic response during endurance exercise / 体力科学

Recent studies indicate that exercise with a low muscle glycogen state enhances exercise-induced metabolic adaptation. However, it is unclear whether metabolic adaptation is involved with muscle glycogen depletion level. In this study, we investigated the effects of prior muscle glycogen depletion level on metabolic response during acute continuous exercise. Seven men completed two experimental trials consisting of two exercise sessions per day. During the first session, participants performed either intermittent exercise (IE) at VO₂max (the IE-CE trial) or continuous exercise (CE) at lactate threshold (the CE-CE trial). During the second session, participants performed 60 minutes of CE at lactate threshold. During this second session, fatty acid oxidation (FAO) was calculated. To determine muscle glycogen content and PGC-1α and PDK-4 mRNA abundance, muscle biopsies were taken at rest after the first session and 2 hours after the second session. After the first session, muscle glycogen content was significantly lower in the IE-CE trial (38.1±5.0 mmol/kg w.w.) than in the CE-CE trial (56.7±10.2 mmol/kg w.w.), <i>P</i><0.05. FAO was higher in the IE-CE trial than the CE-CE trial at baseline and 15 minutes after the second session (both <i>P</i><0.05). PGC-1α mRNA abundance increased after exercise (IE-CE, 5.9±2.5; CE-CE, 2.6±1.3-fold; <i>P</i><0.1). PDK-4 mRNA abundance increased significantly after exercise (IE-CE, 22.2±8.8; CE-CE, 31.5±10.6-fold; <i>P</i><0.05). PGC-1α and PDK-4 mRNA were not significantly different between the trials. In conclusion, continuous exercise with a slightly muscle glycogen-depleted state induced similar level of PGC-1α and PDK-4 mRNA expression, but attenuated FAO, compared to exercise with a moderate muscle glycogen-depleted state.

Effect of Dendrobium officinale Kimura et Migo on substance metabolism and exercise capacity in rats after exercise training / 中国药学杂志

OBJECTIVE: To study the effects of Dendrobium officinale Kimura et Migo on the rats substance metabolism and anti-exercise fatigue capacity in the exercise training. METHODS: High-intensity endurance training rat was as a model. Divided the 6-week-old male (42 d age) Wistar rats 55 into 5 groups of 10 (removed the rats, which are not meeting the requirement): still group (group C), exercise group (group T), exercise ig low-dose Dendrobium officinale Kimura et Migo group of (group TML), exercise ig middle-dose of Dendrobium officinale Kimura et Migo group (group TMM), exercise ig high-dose of Dendrobium officinale Kimura et Migo group (group TMH). Gavage using professional device ig once a day, group TML, Group TMM, group TMH ig dose was 1.5, 3, 4. 5 g · kg-1 · d-1, the ig volume 5 mL · kg-1, Group C and group T were added to ig the same amount of saline. For 24 h after the last training, measured weight, exhaustive swimming time, Hemoglobin and other biochemical markers. RESULTS: The TM each weight no significant differences, and greater than the group T(P < 0.05) less than group C(P < 0.05). TM swimming time is longer than the group C and group T(P < 0.01), and the dose increased and extended. Prolonged exhaustive exercise lead to liver glycogen, muscle glycogen reserves decreased(group T(P < 0.01), groups TM(P < 0.05) lower than in group C. TM each group of liver glycogen [P < 0.05), inositol the original (P < 0.01] higher than the group T, no significant differences between each group of the TM, with the dose increase and higher). In addition, blood urea nitrogen rise[group T(P < 0.01) and groups TM(P < 0.05) blood urea nitrogen higher than in group C. Groups TM is lower than the group T(P < 0.05), TM each non-significant difference]. Hemoglobin decreased [group T(P < 0.01), groups TM(P < 0.05) lower than in group C. Groups TM is higher than the group T(P < 0.05), no significant difference between the TM each]. CONCLUSION: Dendrobium officinale Kimura et Migo supplement can promote protein synthesis, inhibition of amino acid and protein degradation, thereby increasing the hemoglobin content and glycogen reserves, enhanced resistance to fatigue, it has a multi-target, multi-channel features.

Effects of Herba Cistanches on testosterone content, substance metabolism and exercise capacity in rats after exercise training / 中国药学杂志

OBJECTIVE: To study the effects of Herba Cistanches on the content of testosterone, substance metabolism and the ability of resisting exercise-induced fatigue of rats. METHODS: High-intensity endurance trained rats were used as the model. Sixty-five 7-week-old male Wistar rats were divided into 4 groups, with 15 in each group: still ig administration of water group (C group), still igadministration of Cistanche group (M group), exercise ig administration of water group (T group), and exercise ig administration of Cistanche group (TM group). Gavage was done using professional device once a day. M and TM group were dosed at 6.01 g · kg-1 with volume of 5 mL · kg-1, while C and T group were given saline of the same volume. After 42 d exhaustive swimming training, body weight, swimming time, serum testosterone, and other biochemical markers were measured. RESULTS: The body weights and swimming time of the rats in TM group were greater than those in T group (P<0.05, P<0.01). Exhaustive swimming led to decreased serum testosterone. The serum testosterone levels of T group decreased by 40.53% (P<0.01) compared with C group. Compared with T group, the serum testosterone levels of TM group increased by 44.35% (P<0.01). The serum corticosterone levels in each group showed no significant differences, and the serum testosterone/corticosterone ratios changed in line with changes of testosterone. Liver glycogen and muscle glycogen reserves failed. Compared with C group, T group's glycogen decreased by 25.85% (P<0.01), and muscle glycogen decreased by 44. 94% (P<0.01). Compared with T group, TM group had 19.41% higher liver glycogen (P<0.05) and 58.05% higher muscle glycogen (P<0.01); FSH had no significant change; compared with C group, the blood urea of T group increased by 59.30% (P<0.01), and the hemoglobin decreased by 28.72% (P<0.01); compared with T group, TM group had 20.70%) lower blood urea (P<0.05) and 24.22% higher hemoglobin (P<0.05). CONCLUSION: Cistanche deserticola Y.C. Ma can reduce the impact of high-intensity exercise on serum testosterone, and maintain it at normal physiological level. It can promote protein synthesis, inhibit amino acid and protein degradation, and increase hemoglobin and glycogen reserves in rats receiving exercise training.

Characteristics and mechanisms of low-frequency muscle fatigue: alterations in skeletal muscle / 体力科学

Repeated contractions of skeletal muscle cause fatigue, as manifested by a reduced ability to produce force and slowed contraction. During studies of muscle fatigue, a phenomenon known as low-frequency fatigue (LFF) was observed in human skeletal muscles. It is characterized by a greater loss of force in response to low- versus high-frequency muscle stimulation and a long period of time for full recovery. This force deficit is most likely to be owing to disturbances in sarcoplasmic reticulum (SR) Ca²⁺ release and/or reductions in myofibrillar Ca²⁺ sensitivity. Studies on metabolites have implied that inorganic phosphate and Mg²⁺ might have some role in reduced SR Ca²⁺ release that occurs immediately after fatiguing contraction. In addition, recent experiments have shown that impaired myofibril function may relate to increased nitric oxide and hydroxyl radical production, whereas deterioration of SR function may be attributable to increased superoxide production, elevation of cytoplasmic Ca²⁺ concentration and/or decreased muscle glycogen. Finally, we will discuss possible proteins which are affected and contribute to the development of LFF.

Effect of carbohydrate availability on time to exhaustion in exercise performed at two different intensities

This study examined the effects of pre-exercise carbohydrate availability on the time to exhaustion for moderate and heavy exercise. Seven men participated in a randomized order in two diet and exercise regimens each lasting 3 days with a 1-week interval for washout. The tests were performed at 50 percent of the difference between the first (LT1) and second (LT2) lactate breakpoint for moderate exercise (below LT2) and at 25 percent of the difference between the maximal load and LT2 for heavy exercise (above LT2) until exhaustion. Forty-eight hours before each experimental session, subjects performed a 90-min cycling exercise followed by 5-min rest periods and a subsequent 1-min cycling bout at 125 percent VO2max/1-min rest periods until exhaustion to deplete muscle glycogen. A diet providing 10 percent (CHOlow) or 65 percent (CHOmod) energy as carbohydrates was consumed for 2 days until the day of the experimental test. In the exercise below LT2, time to exhaustion did not differ between the CHOmod and the CHOlow diets (57.22 ± 24.24 vs 57.16 ± 25.24 min). In the exercise above LT2, time to exhaustion decreased significantly from 23.16 ± 8.76 min on the CHOmod diet to 18.30 ± 5.86 min on the CHOlow diet (P < 0.05). The rate of carbohydrate oxidation, respiratory exchange ratio and blood lactate concentration were reduced for CHOlow only during exercise above LT2. These results suggest that muscle glycogen depletion followed by a period of a low carbohydrate diet impairs high-intensity exercise performance.

Metabolismo do glicogênio muscular durante o exercício físico: mecanismos de regulação / Muscle glycogen metabolism during exercise: mechanism of regulation

Uma série de estudos tem sido realizada para compreensão do metabolismo de glicogênio muscular durante o exercício. Estudos clássicos apontaram uma associação entre as reservas iniciais de glicogênio muscular e o tempo de sustentação do esforço. O glicogênio muscular diminui de forma semi-logarítmica em função do tempo, mas a concentração desse substrato não chega a zero, o que sugere a participação de outros mecanismos de fadiga na interrupção do exercício prolongado. Nesse tipo de atividade, a depleção de glicogênio, primeiro, ocorre nas fibras de contração lenta, seguida pela depleção nas de contração rápida. A diminuição na taxa de utilização de glicogênio muscular está sincronicamente ligada ao aumento no metabolismo de gordura, mas o mecanismo fisiológico é pouco compreendido. Estudos recentes sugerem que uma diminuição da insulina durante o exercício limitaria o transporte de glicose pela membrana plasmática, causando um aumento no consumo de ácidos graxos. Alguns estudos têm demonstrado, também, que a própria estrutura do glicogênio muscular pode controlar a entrada de ácidos graxos livres na célula, via proteína quinase. Fisicamente, a molécula de glicogênio se apresenta de duas formas, uma com estrutura molecular menor (aproximadamente, 4,10(5) Da, Proglicogênio) e outra maior (aproximadamente, 10(7) Da, Macroglicogênio). Aparentemente, a forma Proglicogênio é metabolicamente mais ativa no exercício e a Macroglicogênio mais suscetível a aumentar com dietas de supercompensação. Maior concentração de hipoxantinas e amônia no exercício com depleção de glicogênio muscular também foi relatada, mas estudos com melhor controle da intensidade do esforço podem ajudar a elucidar essa questão.

A large number of studies have been conducted to understand muscle glycogen metabolism during exercise. Classical studies demonstrated a relationship between the pre-exercise muscle glycogen content and duration of exercise. Muscle glycogen declines in a semilogarithmic manner in function of time, but glycogen concentration does not reach zero, which suggests that other fatigue mechanisms participate in the interruption of prolonged exercise. In this type of activity, glycogen depletion occurs first in slow twitch fibers followed by fast twitch fibers. The decrease in the rate of muscle glycogen utilization is synchronized with an increased rate of fat uptake, but the physiological mechanism is not well understood. Recent studies suggest that the decline of insulin during exercise could be a limiting factor of glucose transport through the plasma membrane, which increases the uptake of fatty acids. Others studies have also demonstrated that the structure of muscle glycogen itself can regulate the cellular uptake of free fatty acids via protein kinase. Physically, the glycogen molecule has two forms, one with a smaller molecular structure (approximately 4.10(5) Da, proglycogen) and another one with a larger molecular structure (approximately 10(7) Da, macroglycogen). Apparently, the proglycogen form is more metabolically active during exercise and the macroglycogen form is more susceptible to increase with supercompensation diets. Higher concentrations of hypoxanthines and ammonia during exercise with muscle glycogen depletion have been reported, but studies that control exercise intensity better are necessary to help shed light on this issue.

Effect of Overtraining on Skeletal Muscle Glycogen,AMPK Activity and Sarcolemma GLUT4 Protein Content in Rats / 中国运动医学杂志

Objective The purpose of the present study was to observe the muscle glucose metabolism by determining the changes in sarcolemma GLUT4 protein content and muscle AMPK activity in overtraining rats.Methods Twenty-seven SD rats were randomly divided into group A(sedentary),group B(underwent endurance exercise 60 minutes/day)and group C(underwent endurance exercise 120 minutes/day).Both exercise groups trained 6 days/wk for 9 weeks.Muscle glycogen,sarcolemma GLUT4 contents and muscle AMPK activity were determined after the 9-week training.Results Sarcolemma GLUT4 content and muscle AMPK activity increased,muscle glycogen contents tended to rise in group B as compared with that in group A.Sarcolemma GLUT4 content and muscle AMPK activity decreased,but muscle glycogen contents were equivalent in group C as compared with that in group B.Conclusion Muscle AMPK activity deceased,and the translocation of GLUT4 protein was inhibited in the overtraining rats.The results could not support a glycogen depletion hypothesis.

Effect of Hyperglycemia and Hyperlipidemia on Cardiac Muscle Glycogen Usage during Exercise in Rats / 영남의대학술지

Rats were studied during 45 minutes treadmill exercise to determine the effects of hyperglycemia and hyperlipidemia on the utilization of cardiac muscle glycogen, and the utilization of diaphragm muscle glycogen was also studied for comparing to cardiac muscle. The hyperglycemia was produced by ingestion of 25% glucose solution(1ml/100gm, BW) and the hyperlipidemia by 10% intralipose ingestion(1ml/100gm, BW) with intraperitoneal injection of heparin(500 IU) 15 minutes before treadmill exercise. The mean blood glucose concentrations(mg/dL) in control and hyperglycemic rats were 110 and 145, respectively, and the mean plasma free fatty acid concentrations(micronEq/L) in control, control exercise(control-E) and hyperlipidemia exercise(HL-E) rats were 247, 260 and 444, respectively. In the hyperglycemic trial, the cardiac muscle glycogen concentration was not significantly decreased by the exercise but the concentration in control rats was decreased to 73.9%(p<0.05). The glycogen concentration of diaphragm was significantly decreased in both groups by the exercise, but the hyperglycemia decreased the glycogen utilization by approximately 10% compared to the control. The cardiac muscle glycogen concentration was not decreased by the exercise in control and hyperlipidemic rats but the utilization of glycogen in hyperlipidemic rats is lower than that of the control. These data illustrate the sparing effect of hyperglycemia on cardiac muscle glycogen usage during exercise, but the effect of hyperlipidemia was not conclusive. In the skeletal muscle, the usage of glycogen by exercise was spared by both hyperglycemia and hyperlipidemia.

Pre-exercise rather than post-exerclse intake of a large meal enhances liver glycogen sparing during endurance exercise in rats / 体力科学

We investigated the effects of feeding a large meal to female rats (n = 66) just before or just after voluntary wheel running on energy metabolism during a final endurance exercise test. The rats were divided into three groups ; one fed a large meal just before exercise (BE), one fed a large meal just after exercise (AE), and one fed <I>ad libitum</I> (AD) . The rats were allowed to run voluntarily from 20 : 00 to 07 : 00 h. The BE group were given a large meal (more than 12 g) between 19 : 00 and 20: 00 h and a small meal (3 g) between 07 : 00 and 08 : 00 h. The AE group were given a large meal (more than 12 g) between 07 : 00 and 08 : 00 h and a small meal (3 g) between 19 : 00 and 20 : 00 h. After 4 weeks, 6 rats in each group were sacrificed at 22 : 00 h, and 12 rats in each group were sacrificed after 30 min starting from 22 : 00 h at 15 m/min (n=6) or 35 m/min (n=6) on a rodent treadmill (0° grade) . Four rats in each group were sacrificed after 30 min starting from 22 : 00 h at rest on the treadmill as a control. The plasma free fatty acid (FFA) and glycerol concentrations increased significantly during low-speed exercise in the AD group, and during higher-speed exercise in all groups. The liver glycogen concentration was significantly greater in the AE group than in the other groups at rest, and decreased significantly during exercise at both speeds in the AD group, but not in the BE and AE groups. The gastrocnemius muscle glycogen concentration was decreased significantly during exercise at both speeds in the AD group, and at high speed in the BE and AE groups.<BR>These results indicate that intake of a large meal just after exercise can store a high level of liver glycogen at the beginning of exercise than <I>ad libitum</I> feeding or large meal intake just before exercise, and expend plasma FFA in muscle during exercise compared with <I>ad libitum</I> feeding. This suggests that large meal intake just after exercise contributes to improvement of metabolic capacity in endurance exercise with enhanced liver glycogen sparing.

Effect of ingestion of two different carbohydrates immediately after exhaustive exercise on muscle glycogen restoration in rats / 体力科学

A study was performed to investigate the effect of ingestion of two different carbohydrates immediately after exhaustive exercise on muscle glycogen restoration in rats. The carbohydrate solu-tions used were 20% maltodextrin (osmolality: 270 mOsm/kg⋅H<SUB>2</SUB>O) and 20% glucose (osmolality: 1370mOsm/kg·H<SUB>2</SUB>O) . At both 30 and 60 min after oral ingestion, the osmolality in the gastric residue was significantly higher in the group given the glucose solution than in the group given the maltodextrin solution. The concentration of serum glucose at both 30 and 60 min after oral ingestion was significantly higher in the group given maltodextrin than in the group given glucose. Compared to the group given glucose, the group given maltodextrin had significantly higher muscle glycogen contents in M. plantaris and M. gastrocnemius at both 30 and 60 min after oral ingestion. Furthermore, the muscle glycogen contents in the group given maltodextrin returned to the levels in resting control rats 60 min after oral ingestion. Thus it is concluded that ingestion of maltodextrin solution immediately after exhaustive exercise might be effective for rapid restoration of muscle glycogen.

METABOLIC ADAPTATIONS TO ENDURANCE TRAINING MONITORED BY BLOOD LACTATE CONCENTRATION IN MALE RATS / 体力科学

We studied the effects of 8 weeks of endurance training on the metabolism in rats. Different treadmill speeds, which corresponded to 2 mM and 4 mM blood lactate concentrations, were used to vary the intensity of the endurance training. After 8 weeks of training, blood lactate concentrations had decreased whereas β-hydroxyacyl-CoA dehydrogenase activity had increased. Citrate synthase activity in the m.extensor digitorum longus (EDL), and m.tibialis anterior (TA) of rats trained at the 4 mM level was higher than in rats trained at the 2 mM level and in control rats. In addition, muscle glycogen content in the hindlimb was higher and muscle TG content in the m.soleus (SOL) was lower in trained rats. These results suggest that training at 4 mM level significantly increases muscle mitochondrial oxidative capacity, and fatty acids are utilized as an energy source regardless of exercise intensity at least in the 2 to 4 mM intensity range. We concludes that an intensity of 4 mM is a useful level with which to elucidate the various adaptations to endurance training.

Effect of hyperglycemia on glycogen repletion after skeletal muscle contraction / 体力科学

Previous studies of the effect of exercise on glucose metabolism in diabetes mellitus have focused on the stimulation of glucose disposal capacity by insulin and muscle contraction. We have investigated the effects of hyperglycemia on the increase in muscle glycogen after exercise and the role of physiological saline (saline) injection under hyperglycemic conditions. Male Wistar rats weighing 100-150g (n=52) were made diabetic (DM) by injection of 90 mg/kg streptozotocin (STZ) . Glycogen content was reduced by in situ electrical stimulation of the sciatic nerve. Immediately after stimulation, the rats were injected with glucose or saline. After a 20 min recovery period, the glycogen content of the white and red gastrocnemius (WG, RG), soleus (SOL), plantaris (PL), extensor digitorum longus (EDL) and tibialis anterior (TA) was significantly increased by glucose injection in the control rats. In DM rats, the glycogen content of the TA and EDL was increased, whereas there was no change in the WG, RG, SOL and PL. These results suggest that, in hyperglycemic rats, muscle glycogen resynthesis in only fast-twitch fibers is increased by muscle contraction. However, after injection of saline, the plasma osmolality decreases significantly and glycogen resynthesis by all muscles except the SOL in diabetic rats is improved, although there is no significant increase in control rats. It is concluded that glycogenolysis and resynthesis after muscle contraction are reduced by hyperglycemia. The data suggest a possible role of saline injection in the development of glycogen resynthesis in hyperglycemia.

The effects of carbohydrate loading on the muscle glycogen content and the bicycling performance in healthy Japanese men / 体力科学

This study was undertaken to examine whether carbohydrate loading gives a good effect to improve the endurance performance in Japanese subjects who had habitually eaten carbohydrate-rich diets. The glycogen content of the vastus lateralis muscle was determined in 6 healthy male subjects with the aid of the needle biopsy technique by setting different diets after glycogen store was depleted by exhaustive exercise.<BR>Glycogen content of the vastus lateralis muscle after mix, low and high carbohydrate diets was 22.7±2.0, 11.6±1.6 and 36.6±4.5 g/wet muscle⋅kg (mean±SD), respectively, while exhaustive time was 75′39″±10′02″, 67′58″±14′11″and 92′10″±22′10″ (mean±SD), respectively. Thus, a good correlation was noted between muscle glycogen content and work time.<BR>It was therefore concluded that the glycogen content of the working muscle was a determinant factor for the capacity to perform long-term heavy exercise and that carbohy-drate loading attained with low carbohydrate diet and exhaustive exercise followed by high carbohydrate diet had a good effect to perform heavy exercise even in Japanese who lived on carbohydrate-rich diet.

EXPERIMENTAL RESEARCH ON THE ANTIFATIGUE EFFECT OF FLAMMULINA VELUTIPES / 营养学报

The present paper reports a systematic research of the antifatigue effect of Flammulina velutipes. The antifatigue effect was judged by the examination of serum lactate dchydrogenase activity, level of blood lactic acid, serum urea nitrogen, muscle and liver glycogen,The experiments indicated that feeding Flammulina velutipes to mice for several days the lactate dehydrogenase activity, muscle and liver glycogeu levels were significantly higher than that of the control. After exercise, the levels of blood lactate and serum urea nitrogen were significantly lower than those of control. After exercise, the recovery rate of lactic acid was much faster than that of control.From the above results, we concluded the Flammulina velutipes may have significant effect on the capability of adaptation to heavy exercise and prevention or elimination of fatigue after exercise.