Consequenes of simulated microgravity on lipid metabolism in humans and effects of proteins supplementation tested as a counter measure

Au cours d’une simulation de la microgravité de 21 jours, le développement de plusieurs altérations métaboliques ont été étudiées : une inflammation de bas-niveau et une altération de la sensibilité à l’insuline et du métabolisme lipidique. Connues pour leurs impacts positifs sur le métabolisme, une supplémentation en protéines du petit lait, combinée à des sels alcalins, a également été testée.Contrairement aux études précédentes, aucune inflammation, ni altération du métabolisme lipidique n’a été clairement décrite dans notre étude. En revanche une diminution de l’oxydation des glucides en faveur des lipides est observée, suggérant le début d’une insensibilité à l’insuline. Nos données suggèrent qu’il serait possible de prévenir les dérégulations métaboliques associées à l’inactivité physique sévère par un remplacement isocalorique des lipides par les protéines, avec un apport protéique de base de 1,2g/kg/jour et un contrôle strict de la balance énergétique par l’apport calorique.During 21 days of simulated microgravity, the development of several metabolic alterations has been studied: a low-grade inflammation and an alteration of insulin sensitivity and lipid metabolism. Known for their positive effect on metabolism, whey proteins supplementation combined with alkaline salts have also been tested. At the opposite of previous studies, no inflammation, nor lipid metabolism alterations have clearly been described. Nevertheless, a decrease in carbohydrates oxidation in favor of lipids is observed, suggesting the development of insulin insensitivity. Our data suggest that it may be possible to prevent the metabolic disorders associated with severe physical inactivity by anisocaloric replacement of lipids by proteins in the diet, along with a protein intake of 1.2g/kg/day and tight control of energy balance by adjusting energy intake

Consequenes of simulated microgravity on lipid metabolism in humans and effects of proteins supplementation tested as a counter measure

Au cours d’une simulation de la microgravité de 21 jours, le développement de plusieurs altérations métaboliques ont été étudiées : une inflammation de bas-niveau et une altération de la sensibilité à l’insuline et du métabolisme lipidique. Connues pour leurs impacts positifs sur le métabolisme, une supplémentation en protéines du petit lait, combinée à des sels alcalins, a également été testée.Contrairement aux études précédentes, aucune inflammation, ni altération du métabolisme lipidique n’a été clairement décrite dans notre étude. En revanche une diminution de l’oxydation des glucides en faveur des lipides est observée, suggérant le début d’une insensibilité à l’insuline. Nos données suggèrent qu’il serait possible de prévenir les dérégulations métaboliques associées à l’inactivité physique sévère par un remplacement isocalorique des lipides par les protéines, avec un apport protéique de base de 1,2g/kg/jour et un contrôle strict de la balance énergétique par l’apport calorique.During 21 days of simulated microgravity, the development of several metabolic alterations has been studied: a low-grade inflammation and an alteration of insulin sensitivity and lipid metabolism. Known for their positive effect on metabolism, whey proteins supplementation combined with alkaline salts have also been tested. At the opposite of previous studies, no inflammation, nor lipid metabolism alterations have clearly been described. Nevertheless, a decrease in carbohydrates oxidation in favor of lipids is observed, suggesting the development of insulin insensitivity. Our data suggest that it may be possible to prevent the metabolic disorders associated with severe physical inactivity by anisocaloric replacement of lipids by proteins in the diet, along with a protein intake of 1.2g/kg/day and tight control of energy balance by adjusting energy intake

Conséquences d’une simulation d’impesanteur de 21 jours chez l’homme sur le métabolisme des lipides et effets d’une supplémentation en protéines testée comme contremesure

During 21 days of simulated microgravity, the development of several metabolic alterations has been studied: a low-grade inflammation and an alteration of insulin sensitivity and lipid metabolism. Known for their positive effect on metabolism, whey proteins supplementation combined with alkaline salts have also been tested. At the opposite of previous studies, no inflammation, nor lipid metabolism alterations have clearly been described. Nevertheless, a decrease in carbohydrates oxidation in favor of lipids is observed, suggesting the development of insulin insensitivity. Our data suggest that it may be possible to prevent the metabolic disorders associated with severe physical inactivity by anisocaloric replacement of lipids by proteins in the diet, along with a protein intake of 1.2g/kg/day and tight control of energy balance by adjusting energy intake.Au cours d’une simulation de la microgravité de 21 jours, le développement de plusieurs altérations métaboliques ont été étudiées : une inflammation de bas-niveau et une altération de la sensibilité à l’insuline et du métabolisme lipidique. Connues pour leurs impacts positifs sur le métabolisme, une supplémentation en protéines du petit lait, combinée à des sels alcalins, a également été testée.Contrairement aux études précédentes, aucune inflammation, ni altération du métabolisme lipidique n’a été clairement décrite dans notre étude. En revanche une diminution de l’oxydation des glucides en faveur des lipides est observée, suggérant le début d’une insensibilité à l’insuline. Nos données suggèrent qu’il serait possible de prévenir les dérégulations métaboliques associées à l’inactivité physique sévère par un remplacement isocalorique des lipides par les protéines, avec un apport protéique de base de 1,2g/kg/jour et un contrôle strict de la balance énergétique par l’apport calorique

Physical inactivity as the culprit of metabolic inflexibility: Evidences from bed-rest studies.

International audienceAlthough it is no longer debatable that sedentary behaviors are an actual cause of many metabolic diseases, the physiology of physical inactivity has been poorly investigated for this purpose. Along with microgravity, the physiological adaptations to space flights require metabolic adaptations to physical inactivity and that is exceedingly well simulated during the ground-based microgravity bed-rest analogs. Bed-rest thus represents a unique model to investigate the mechanisms by which physical inactivity leads to the development of current societal chronic diseases. For decades, however, clinicians and physiologists working in space research have worked separately without taking full awareness of potential strong mutual questioning. This review summarizes the data collected over the last 60 years on metabolic adaptations to bed-rest in healthy subjects. Our aim is to provide evidence which support the hypothesis that physical inactivity per se is one of the primary causes in the development of metabolic inflexibility. This evidence will focus on four main tenants of metabolic inflexiblity: 1) insulin resistance, 2) impaired lipid trafficking and hyperlipidemia, 3) a shift in substrate use towards glucose, 4) a shift in muscle fiber type and ectopic fat storage. Altogether, this hypothesis places sedentary behaviors upstream on the list of factors involved in metabolic inflexibility which is considered to be a primary impairment in several metabolic disorders such as obesity, insulin-resistance and type 2 diabetes mellitus

Effects of different levels of physical inactivity on plasma visfatin in healthy normal-weight men.

International audienceWe tested whether physical inactivity (PI) is an independent predictor of plasma visfatin, a newly discovered adipokine likely involved in the relationship between obesity-associated low-grade inflammation and insulin resistance. PI was induced in healthy men (Body Mass Index = 23.4 ± 0.6 kg*m(-2)) by 10 days of confinement (n = 8), 1 month of detraining (n = 10), and 3 months of bed rest with (n = 7) and without exercise (n = 8). Visfatin was negatively associated with activity energy expenditure (p = 0.03). No relationship was observed with insulin sensitivity. This suggested that PI itself increases visfatin concentrations

Effect of enforced physical inactivity induced by 60-d of bed rest on hepatic markers of NAFLD in healthy normal-weight women

International audienc

Bed rest and resistive vibration exercise unveil novel links between skeletal muscle mitochondrial function and insulin resistance

International audienceAims/hypothesis Physical inactivity has broad implications forhuman disease including insulin resistance, sarcopenia and obesity.The present study tested the hypothesis that (1) impairedmitochondrial respiration is linked with blunted insulin sensitivityand loss of muscle mass in healthy young men, and (2)resistive vibration exercise (RVE) would mitigate the negativemetabolic effects of bed rest.Methods Participants (n = 9) were maintained in energy balanceduring 21 days of bed rest with RVE and without (CON)in a crossover study. Mitochondrial respiration was determinedby high-resolution respirometry in permeabilised fibre bundlesfrom biopsies of the vastus lateralis. A hyperinsulinaemic–euglycaemic clamp was used to determine insulin sensitivity,and body composition was assessed by dual-energy x-ray absorptiometry(DEXA).Results Body mass (−3.2 ± 0.5 kg vs −2.8 ± 0.4 kg for CON andRVE, respectively, p < 0.05), fat-free mass (−2.9 ± 0.5 kg vs−2.7 ± 0.5 kg, p < 0.05) and peak oxygen consumption(V⋅O2peak) (10–15%, p < 0.05) were all reduced following bedrest. Bed rest decreased insulin sensitivity in the CON group(0.04 ± 0.002 mg kgFFM−1 [pmol l−1] min− 1 vs0.03 ± 0.002 mg kgFFM−1 [pmol l−1] min−1 for baseline vspost-CON), while RVE mitigated this response(0.04 ± 0.003 mg kgFFM−1 [pmol l−1] min−1). Mitochondrialrespiration (oxidative phosphorylation and electron transport systemcapacity) decreased in the CON group but not in the RVEgroup when expressed relative to tissue weight but not whennormalised for citrate synthase activity. LEAK respiration, indicatinga decrease in mitochondrial uncoupling, was the onlycomponent to remain significantly lower in the CON group afternormalisation for citrate synthase. This was accompanied by asignificant decrease in adenine nucleotide translocase proteincontent.Conclusions/interpretation Reductions in muscle mitochondrialrespiration occur concomitantly with insulin resistanceand loss of muscle mass during bed rest and may play a role inthe adaptations to physical inactivity. Significantly, we showthat RVE is an effective strategy to partially prevent some ofthe deleterious metabolic effects of bed rest

A combination of whey protein and potassium bicarbonate supplements during head-down-tilt bed rest: Presentation of a multidisciplinary randomized controlled trial (MEP study)

Inactivity, as it appears during space flight and in bed rest, induces reduction of lean body and bone mass, glucose intolerance, and weakening of the cardiovascular system. Increased protein intake, whey protein in particular, has been proposed to counteract some of these effects, but has also been associated with negative effects on bone, likely caused by a correspondingly high ratio of acid to alkali precursors in the diet. The main hypothesis of the presented cross-over study (MEP study) was that supplementing high protein intake (1.2 g/kg body weight/d plus 0.6 g/kg body weight/d whey protein) with alkaline salts (90 mmol potassium bicarbonate/d) will maintain lean body mass during bed rest without increasing bone resorption. A 21-day head-down-tilt bed rest study was performed to examine several physiological systems in a multidisciplinary approach. Ten healthy men (age: 31±6 years; body weight: 76.5±5.6 kg) were randomly assigned to the dietary countermeasure or isocaloric control first, one test subject randomized to the dietary countermeasure first dropped out after the first campaign

Effectiveness of Resistive Vibration Exercise and Whey Protein Supplementation Plus Alkaline Salt on the Skeletal Muscle Proteome Following 21 Days of Bed Rest in Healthy Males

International audienceMuscle atrophy is a deleterious consequence of physical inactivity and is associated with increased morbidity and mortality. The aim of this study was to decipher the mechanisms involved in disuse muscle atrophy in eight healthy men using a 21 day bed rest with a cross-over design (control, with resistive vibration exercise (RVE), or RVE combined with whey protein supplementation and an alkaline salt (NEX)). The main physiological findings show a significant reduction in whole-body fat-free mass (CON −4.1%, RVE −4.3%, NEX −2.7%, p < 0.05), maximal oxygen consumption (CON −20.5%, RVE −6.46%, NEX −7.9%, p < 0.05), and maximal voluntary contraction (CON −15%, RVE −12%, and NEX −9.5%, p < 0.05) and a reduction in mitochondrial enzyme activity (CON −30.7%, RVE −31.3%, NEX −17%, p < 0.05). The benefits of nutrition and exercise countermeasure were evident with an increase in leg lean mass (CON −1.7%, RVE +8.9%, NEX +15%, p < 0.05). Changes to the vastus lateralis muscle proteome were characterized using mass spectrometry-based label-free quantitative proteomics, the findings of which suggest alterations to cell metabolism, mitochondrial metabolism, protein synthesis, and degradation pathways during bed rest. The observed changes were partially mitigated during RVE, but there were no significant pathway changes during the NEX trial. The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium with the dataset identifier PXD006882. In conclusion, resistive vibration exercise, when combined with whey/alkalizing salt supplementation, could be an effective strategy to prevent skeletal muscle protein changes, muscle atrophy, and insulin sensitivity during medium duration bed rest