Czas trwania jest istotny
Z tego co ja wiem Phinney mówił, że po 4-6 tygodniach adaptacji zawodowi kolarze których badał przy diecie ketogennej mieli taka samą wydolność o charakterze wytrzymałościowym jak na swojej standardowej diecie. Mówił też, że niektórzy zauważyli minimalny dyskomfort przy jeżdzie pod górkę, gdzie intensywność rosła... być może potrzebna jest dłuższa adaptacja: acylotransferaza karnitynowa to jak wiemy z badań `oporny` enzym, myślę, że zmiany w obrębie jej aktywności mogą być kluczowe.
Utrzymanie intensywności treningu siłowego to jedna sprawa, budowa masy mieśniowej to druga. Tutaj ostatnio Anssi Manninen sporo ma do powiedzenia, niestety do niektórych jego publikacji dotyczących diet ketogennych i
LBM nie ma dostępu nawet do abstractów... Z jednego opracowania na takie teksty zwróciłem uwagę: jeden dotyczy wpływu ciał ketonowych na hamowanie proteolizy, promowanie syntezy protein, ale drugi jest chyba jeszcze ciekawszy
Effect of beta-hydroxybutyrate on whole-body leucine kinetics and fractional mixed skeletal muscle protein synthesis in humans.
Nair KS, Welle SL, Halliday D, Campbell RG.
Department of Medicine, University of Rochester School of Medicine and Dentistry, NY 14603.
Because intravenous infusion of beta-hydroxybutyrate (beta-OHB) has been reported to decrease urinary nitrogen excretion, we investigated in vivo metabolism of leucine, an essential amino acid, using L-[1-13C]leucine as a tracer during beta-OHB infusion. Leucine flux during beta-OHB infusion did not differ from leucine flux during normal saline infusion in nine normal subjects, whereas leucine oxidation decreased 18-41% (mean = 30%) from 18.1 +/- 1.1 mumol.kg-1.h-1 (P less than 0.01), and incorporation of leucine into skeletal muscle protein increased 5-17% (mean = 10%) from 0.048 + 0.003%/h (P less than 0.02). Since blood pH during beta-OHB infusion was higher than the pH during saline infusion, we performed separate experiments to study the effect of increased blood pH on leucine kinetics by infusing sodium bicarbonate intravenously. Blood pH during sodium bicarbonate infusion was similar to that observed during the beta-OHB infusion, but bicarbonate infusion had no effect on leucine flux or leucine oxidation. We conclude that beta-OHB decreases leucine oxidation and promotes protein synthesis in human beings.
Effects of dietary carbohydrate restriction with high protein intake on protein metabolism and the somatotropic axis.
Harber MP, Schenk S, Barkan AL, Horowitz JF.
University of Michigan, Division of Kinesiology, 401 Washtenaw Avenue, Ann Arbor, Michigan 48109-2208, USA.
CONTEXT: Alterations in dietary macronutrient intake can influence protein turnover. OBJECTIVE: The purpose of this study was to assess the influence of a low-carbohydrate/high-protein diet (LC/HP) on skeletal muscle protein synthesis and whole-body proteolysis, without the confounding influence of a negative energy balance. DESIGN: Nine-day dietary intervention was applied. SETTING: Subjects remained in the General Clinical Research Center throughout the 9-d study. PARTICIPANTS: Eight young, healthy volunteers participated. INTERVENTION: Subjects ate a typical Western diet (60% carbohydrate, 30% fat, 10% protein) for 2 d, followed immediately by 7 d of an isocaloric LC/HP (5% carbohydrate, 60% fat, 35% protein). MAIN OUTCOME MEASURES: Skeletal muscle fractional synthetic rate and whole-body proteolysis [leucine rate of appearance in plasma (Ra)] were measured after an overnight fast before and after 2 and 7 d of LC/HP. We also measured plasma concentrations of insulin, GH, and IGF-I. RESULTS: Leucine Ra was increased (P = 0.03) after 2 and 7 d of LC/HP, and muscle fractional synthetic rate was approximately 2-fold higher (P < 0.01) after 7 d of LC/HP. Fat free mass was not altered by LC/HP. Average 24-h plasma insulin concentration was 50% lower (P < 0.001) after 2 and 7 d of LC/HP, whereas GH secretion and total plasma IGF-I concentrations were unchanged with LC/HP. However, plasma free IGF-I decreased by approximately 30% after 7 d of LC/HP (P = 0.002), whereas muscle IGF-I mRNA increased about 2-fold (P = 0.05). CONCLUSIONS: Increasing dietary protein content during a 7-d carbohydrate restricted diet stimulated muscle protein synthesis and whole-body proteolysis without a measurable change in fat free mass.
Zmieniony przez - ellis w dniu 2006-11-26 22:06:42