Glycogen resynthesis in the absence of food ingestion during recovery from moderate or high intensity physical activity: novel insights from rat and human studies

Fournier, Paul A.; Bräu, Lambert; Ferreira, Luis D.; Fairchild, Timothy J.; Raja, Ghazala Kaukab; James, Anthony P.; Palmer, T.N.

doi:10.1016/s1095-6433(02)00254-4

Cited by 44 publications

(37 citation statements)

References 37 publications

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“…Lactate, amino acids, muscle glycolytic intermediates, and glycerol are known or potential substrates for glyconeogenesis (29). However, those substrates and known pathways for glycogen synthesis would not result in high 2 H enrichment of both the H1 and H2 position of the glucosyl unit of muscle glycogen.…”

Section: Discussionmentioning

confidence: 99%

Role of Excess Glycogenolysis in Fasting Hyperglycemia Among Pre-Diabetic and Diabetic Zucker (fa/fa) Rats

et al. 2007

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Sources of plasma glucose and glucose turnover were investigated in 8-week-old (pre-diabetic) and 13-week-old (diabetic) Zucker (fa/fa) rats after a 24-h fast. Intraperitoneal 2 H 2 O was administered and [3,4-13 C 2 ]glucose and [U-13 C 3 ]propionate were infused into conscious active rats. 13 C nuclear magnetic resonance analysis of monoacetone glucose derived from blood glucose indicated that glucose production was increased significantly in 8-and 13-weekold fa/fa rats compared with age-matched Zucker (؉/؉) rats, and hepatic glycogen was dramatically higher among fa/fa animals regardless of age. Glycogenolysis, essentially 0 in ؉/؉ rats after a 24-h fast, was significant in fa/fa rats (11 ؎ 6 and 17 ؎ 7% of glucose production in 8-and 13-week-old rats, respectively), even after a 24-h fast. Tricarboxylic acid (TCA) cycle flux and efflux of carbon skeletons from the cycle (cataplerosis) were both significantly higher in fa/fa rats compared with controls, but net gluconeogenesis from the TCA cycle was not higher because products leaving the cycle were returned to the cycle via a pyruvate cycling pathway. Thus, pyruvate cycling flux increased in proportion to TCA cycle flux, leaving net gluconeogenesis unchanged in fa/fa animals compared with control animals. The distribution of 2 H in skeletal muscle glycogen suggested that at least a fraction of glucose molecules entering glycogen pass through phosphomannose isomerase. Diabetes 56:777-785, 2007

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Section: Discussionmentioning

confidence: 99%

Role of Excess Glycogenolysis in Fasting Hyperglycemia Among Pre-Diabetic and Diabetic Zucker (fa/fa) Rats

et al. 2007

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“…In some mammal species, such as in rats and humans, the extent of this replenishment is only partial (Hermansen and Vaage, 1977;Astrand et al, 1986;Choi et al, 1994;Nikolovski et al, 1996;Peters et al, 1996;Bangsbo et al, 1997;Ferreira et al, 2001;Fournier et al, 2002), thus suggesting that a few consecutive bouts of high-intensity exercise might eventually lead to the progressive depletion of their muscle glycogen stores. In order to test this prediction, groups of rats were subjected to a series of three bouts of highintensity swims to exhaustion, each separated from the subsequent one by a recovery period previously shown to be long enough for muscle glycogen and lactate to return to stable levels (Ferreira et al, 2001).…”

Section: Discussionmentioning

confidence: 99%

“…Since, in the present study, the animals were in a fasted state, the synthesis of muscle glycogen had to depend solely on endogenous substrates. The lactate built up in response to exercise is a likely candidate (Fig.·3), as it is generally acknowledged as one of the major carbon sources for the synthesis of muscle glycogen in many vertebrate species (Gleeson, 1996;Palmer and Fournier, 1997;Fournier et al, 2002). That lactate is also likely to be a major carbon source for the replenishment of muscle glycogen during recovery from each bout of exercise in rats is suggested indirectly by the observation that the fall in plasma and muscle lactate levels is temporally linked with glycogen synthesis.…”

Section: Discussionmentioning

confidence: 99%

“…Identical superscripts on different data points indicate the absence of significant differences, whereas data points without a superscript differ significantly between each other and from any data point bearing a superscript (ANOVA followed by Fisher PLSD a posteriori test; P<0.05). Glycogen sparing post-exercise in rats contribute to the replenishment of muscle glycogen (Gaesser and Brooks, 1980;Fournier et al, 2002), but their relative contributions, as well as that of lactate, remain to be established. The mechanisms by which the proportion of muscle glycogen replenished post-exercise differs between the first and subsequent bouts of exercise remain to be elucidated.…”

Section: Discussionmentioning

confidence: 99%

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Repeated bouts of high-intensity exercise and muscle glycogen sparing in the rat

Raja

Bräu

Palmer

et al. 2003

Journal of Experimental Biology

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SUMMARY Even in the absence of food intake, several animal species recovering from physical activity of high intensity can replenish completely their muscle glycogen stores. In some species of mammals, such as in rats and humans,glycogen repletion is only partial, thus suggesting that a few consecutive bouts of high-intensity exercise might eventually lead to the sustained depletion of their muscle glycogen. In order to test this prediction, groups of rats with a lead weight of 10% body mass attached to their tails were subjected to either one, two or three bouts of high-intensity swimming, each bout being separated from the next by a 1 h re covery period. Although glycogen repletion after the first bout of exercise was only partial, all the glycogen mobilised in subsequent bouts was completely replenished during the corresponding recovery periods and irrespective of muscle fibre compositions. The impact of repeated bouts of high-intensity exercise on plasma levels of fatty acids, acetoacetate and β-hydroxybutyrate suggests that the metabolic state of the rat prior to the second and third bouts of exercise was different from that before the first bout. In conclusion, rats resemble other vertebrate species in that without food intake there are conditions under which they can replenish completely their muscle glycogen stores from endogenous carbon sources when recovering from high-intensity exercise. It remains to be established, however, whether this capacity is typical of mammals in general.

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“…The elevated levels of glucose 6-phosphate at the onset of recovery in this study might contribute to the initial activation of glycogen synthesis, but the early return of this metabolite to basal pre-exercise levels, despite ongoing glycogen synthesis until late into recovery, suggests that glucose 6-phosphate does not play a major role in the control of glycogen synthesis during late recovery (Fig.·3). This constitutes one of several physiological conditions where changes in glucose 6-phosphate levels do not play a major role in the control of the rate of glycogen synthesis in skeletal muscles (James et al, 1998;Lawrence and Roach, 2000;Fournier et al, 2002).…”

Section: ) Glycogen Synthesis Post-exercisementioning

confidence: 99%

Lactate availability is not the major factor limiting muscle glycogen repletion during recovery from an intense sprint in previously active fasted rats

Raja

Mills

Palmer

et al. 2004

Journal of Experimental Biology

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SUMMARY It is not clear whether the amount of accumulated lactate is the main factor limiting muscle glycogen accumulation during recovery from an intense sprint performed by previously active fasted laboratory rats. To address this question, groups of fasted rats swam at moderate intensity for 30 min, each animal with a lead weight equivalent to 0.5% body mass attached to its tail,followed by a 3 min high intensity swim with a 10% lead weight and a recovery period of up to 2 hours afterwards. Moderately intense exercise for 30 min caused a decrease in muscle glycogen levels in the mixed, white and red gastrocnemius and the mixed quadriceps muscles, and a further rapid fall occurred in response to the 3 min sprint effort. During recovery, glycogen increased to comparable or above pre-sprint levels across all muscles, and this occurred to a large extent at the expense of net carbon sources other than lactate, with these carbon sources accounting for at least 36–65%of the glycogen deposited. The sustained dephosphorylation-mediated activation of glycogen synthase, but not the changes in glucose 6-phosphate levels, most probably played an important role in enabling the replenishment of muscle glycogen stores. In conclusion, our findings suggest that the amount of glycogen deposited during recovery from high intensity exercise in fasted animals is not limited by the amount of accumulated lactate.

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Glycogen resynthesis in the absence of food ingestion during recovery from moderate or high intensity physical activity: novel insights from rat and human studies

Cited by 44 publications

References 37 publications

Role of Excess Glycogenolysis in Fasting Hyperglycemia Among Pre-Diabetic and Diabetic Zucker (fa/fa) Rats

Role of Excess Glycogenolysis in Fasting Hyperglycemia Among Pre-Diabetic and Diabetic Zucker (fa/fa) Rats

Repeated bouts of high-intensity exercise and muscle glycogen sparing in the rat

Lactate availability is not the major factor limiting muscle glycogen repletion during recovery from an intense sprint in previously active fasted rats

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