These results demonstrate that consuming a commercially available ED before exercise can improve endurance performance and that this improvement might be in part the result of increased effort without a concomitant increase in perceived exertion.

Our laboratory recently reported that chronic resistance training (RT) improved insulin-stimulated glucose transport in normal rodent skeletal muscle, owing, in part, to increased GLUT-4 protein concentration (Yaspelkis BB III, Singh MK, Trevino B, Krisan AD, and Collins DE. Acta Physiol Scand 175: 315-323, 2002). However, it remained to be determined whether these improvements resulted from alterations in the insulin signaling cascade as well. In addition, the possibility existed that RT might improve skeletal muscle insulin resistance. Thirty-two male Sprague-Dawley rats were assigned to four groups: control diet (Con)-sedentary (Sed); Con-RT; high-fat diet (HF)-Sed; and HF-RT. Animals consumed their respective diets for 9 wk; then RT animals performed 12 wk of training (3 sets, 10 repetitions at 75% one-repetition maximum, 3x/wk). Animals remained on their dietary treatments over the 12-wk period. After the training period, animals were subjected to hindlimb perfusions. Insulin-stimulated insulin receptor substrate-1-associated phosphatidylinositol-3 kinase activity was enhanced in the red gastrocnemius and quadriceps of Con-RT and HF-RT animals. Atypical PKC-zeta/lambda and Akt activities were reduced in HF-Sed and normalized in HF-RT animals. Resistance training increased GLUT-4 protein concentration in red gastrocnemius and quadriceps of Con-RT and HF-RT animals. No differences were observed in total protein concentrations of insulin receptor substrate-1, Akt, atypical PKC-zeta/lambda, or phosphorylation of Akt. Collectively, these findings suggest that resistance training increases insulin-stimulated carbohydrate metabolism in normal skeletal muscle and reverses high-fat diet-induced skeletal muscle insulin resistance by altering components of both the insulin signaling cascade and glucose transporter effector system.

Ivy. The effect of a carbohydrate and protein supplement on resistance exercise performance, hormonal response, and muscle damage. J. Strength Cond. Res. 21(2): 321-329. 2007.-The purpose of this study was to determine whether resistance exercise performance and postexercise muscle damage were altered when consuming a carbohydrate and protein beverage (CHO-PRO; 6.2% and 1.5% concentrations). Thirty-four male subjects (age: 21.5 Ϯ 1.7 years; height: 177.3 Ϯ 1.1 cm; weight: 77.2 Ϯ 2.2 kg) completed 3 sets of 8 repetitions at their 8 repetition maximum to volitional fatigue. The exercise order consisted of the high pull, leg curl, standing overhead press, leg extension, lat pull-down, leg press, and bench press. In a double-blind, posttest-only control group design, subjects consumed 355 ml of either CHO-PRO or placebo (electrolyte and artificial sweetener beverage) 30 minutes prior to exercise, 177 ml immediately prior to exercise, 177 ml halfway through the exercise bout, and 355 ml immediately following the exercise bout. There were no significant differences between groups relative to exercise performance. Cortisol was significantly elevated in the placebo group compared to the CHO-PRO group at 24 hours postexercise. Insulin was significantly elevated immediately pre-exercise, after the fourth lift, immediately postexercise, 1 hour, and 6 hours postexercise in CHO-PRO compared to the placebo group. Myoglobin levels in the placebo group approached significance halfway through the exercise bout and at 1 hour postexercise (p ϭ 0.06 and 0.07, respectively) and were significantly elevated at 6 hours postexercise compared to the CHO-PRO group. Creatine kinase levels were significantly elevated in the placebo group at 24 hours postexercise compared to the CHO-PRO group. The CHO-PRO supplement did not improve performance during a resistance exercise bout, but appeared to reduce muscle damage, as evidenced by the responses of both myoglobin and creatine kinase. These results suggest the use of a CHO-PRO supplement during resistance training to reduce muscle damage and soreness.

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Abstract:The purpose of this study was to investigate the effect of green tea extract (GTE) supplementation combined with endurance training on endurance capacity and performance in sedentary men. Forty untrained men (age: 20 ± 1 years) participated in this study. Subjects were assigned to 1 of 4 treatments: (i) placebo-control (CTRL), (ii) GTE, (iii) endurance training (Ex), and (iv) endurance training with GTE (ExGTE). During the 4-week intervention, exercise training was prescribed as 75% oxygen uptake reserve for three 20-min sessions per week, and either GTE (250 mg/day) or placebo was provided. Endurance capacity, malondialdehyde (MDA), total antioxidant status (TAS), and creatine kinase (CK) were examined. Ex and ExGTE but not GTE improved exhaustive-run time (Ex: +8.2%, p = 0.031; ExGTE: +14.3%, p < 0.001); in addition, Ex and ExGTE significantly increased maximal oxygen uptake by ϳ14% (p = 0.041) and ϳ17% (p = 0.017) above the values of the CTRL group, respectively. Both Ex and ExGTE significantly decreased the increase of CK by ϳ11%-32% below that of CTRL following an exhaustive run (Ex: p = 0.007; ExGTE: p = 0.001). Moreover, TAS levels increased by ϳ11% in ExGTE after training (p = 0.040), and GTE, Ex, and ExGTE markedly attenuated exercise-induced MDA production (p = 0.01, p = 0.005, p = 0.011, respectively). In conclusion, this investigation demonstrated that daily ingestion of GTE during endurance training does not impair improvements in endurance capacity. Moreover, endurance training combined with GTE not only increases antioxidant capacity without attenuating endurance training adaptations, but also further attenuates acute exercise-induced CK release.Key words: V O 2max , malondialdehyde (MDA), creatine kinase (CK), oxidative stress, catechins.Résumé : Cette étude se propose d'examiner l'effet de la supplémentation en extrait de thé vert (« GTE ») combinée à l'entraînement en endurance sur la capacité d'endurance et la performance chez des hommes sédentaires. Quarante hommes non entraînés (âge de 20 ± 1 ans) participent à cette étude. Les sujets sont assignés à l'un des quatre traitements : (i) placebocontrôle (« CTRL »), (ii) GTE, (iii) entraînement en endurance (Ex) et (iv) entraînement en endurance plus GTE (ExGTE). Durant les quatre semaines de l'intervention, l'entraînement physique consiste en trois séances de 20 min à une intensité sollicitant 75 % du consommation d'oxygène de réserve dans la condition de GTE (250 mg/jour) ou de placebo. On évalue la capacité d'endurance, le taux de malonaldéhyde (« MDA »), le statut antioxydant total (« TAS ») et la créatine kinase (« CK »). Ex et ExGTE, mais pas GTE suscitent une amélioration du temps de course jusqu'à épuisement (Ex: +8,2 %, p = 0,031; ExGTE: +14,3 %, p < 0,001); de plus, Ex et ExGTE suscitent une augmentation significative du consommation maximale d'oxygène de ϳ14 % (p = 0,041) et de ϳ17 % (p = 0,017) respectivement par rapport au groupe CTRL. EX et ExGTE suscitent une baisse significative de l'augmentation de CK de ϳ11-32 % par rap...

The green fluorescent protein (GFP) was used as a marker to study the intracellular transport of vacuolar and secretory proteins in yeast. Therefore, the following gene constructs were expressed in Saccharomyces cerevisiae under control of the GAL1 promoter: GFP N-terminally fused to the yeast secretory invertase (INV-GFP), the plant vacuolar chitinase (CHN-GFP) and its secretory derivative (CHNDeltaVTP-GFP), which did not contain the vacuolar targeting peptide (VTP), both chitinase forms (CHN and CHNDeltaVTP), GFP without any targeting information and two secretory GFP variants with and without the VTP of chitinase (N-GFP-V and N-GFP). Whereas chitinase without VTP is accumulated in the culture medium the other gene products are retained inside the cell up to 48 h of induction. Independently of a known VTP they are transported to the vacuole, so far as they contain a signal peptide for entering the endoplasmic reticulum. This was demonstrated by confocal laser scanning microscopy, immunocytochemical analysis and subcellular fractionation experiments as well. The transport of the GFP fusion proteins is temporary delayed by a transient accumulation in electron-dense structures very likely derived from the ER, because they also contain the ER chaperone Kar2p/Bip. Our results demonstrate that GFP directs secretory proteins without VTP to the yeast vacuole, possibly by the recognition of an unknown vacuolar signal and demonstrates, therefore, a first limitation for the application of GFP as a marker for the secretory pathway in yeast.

The aims of this investigation were to evaluate the effect of an amino acid supplement on the glucose response to an oral glucose challenge ( experiment 1) and to evaluate whether differences in blood glucose response were associated with increased skeletal muscle glucose uptake ( experimental 2). Experiment 1 rats were gavaged with either glucose (CHO), glucose plus an amino acid mixture (CHO-AA-1), glucose plus an amino acid mixture with increased leucine concentration (CHO-AA-2), or water (PLA). CHO-AA-1 and CHO-AA-2 had reduced blood glucose responses compared with CHO, with no difference in insulin among these treatments. Experiment 2 rats were gavaged with either CHO or CHO-AA-1. Fifteen minutes after gavage, a bolus containing 2-[3H]deoxyglucose and [U-14C]mannitol was infused via a tail vein. Blood glucose was significantly lower in CHO-AA-1 than in CHO, whereas insulin responses were similar. Muscle glucose uptake was higher in CHO-AA-1 compared with CHO in both fast-twitch red (8.36 ± 1.3 vs. 5.27 ± 0.7 μmol·g−1·h−1) and white muscle (1.85 ± 0.3 vs. 1.11 ± 0.2 μmol·g−1·h−1). There was no difference in Akt/PKB phosphorylation between treatment groups; however, the amino acid treatment resulted in increased AS160 phosphorylation in both muscle fiber types. Glycogen synthase phosphorylation was reduced in fast-twitch red muscle of CHO-AA-1 compared with CHO, whereas mTOR phosphorylation was increased. These differences were not noted in fast-twitch white muscle. These findings suggest that amino acid supplementation can improve glucose tolerance by increasing skeletal muscle glucose uptake and intracellular disposal through enhanced intracellular signaling.