Effects of strength training and supplementation with different milk proteins on regulation of muscle mass in young and elderly
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The ability to maintain a normal muscle masss or to increase muscle mass from a subotimal level, is of great interest from both a sports and health perspective. The health perspective is especially important for our growing elderly population, because the age dependent loss of muscle mass and strength limits participation in daily activites and increases the presence of comorbidities and risk of mortality. In healthy adult individuals changes in muscle mass is mainly regulated by changes in physical activity and diet; especially protein intake and energy balance. The importance of a well balanced diet with a suffcient protein intake is undisputed. Still, whether supplementing the diet with additional protein in the form of supplements offers an extra effect is debated. Furthermore, the role of protein quality of these supplements is unclear. The aim of this thesis was to compare the acute and long-term muscle anabolic effects of supplementation with three differnet milk protein products: 1) native whey, containing high levels of the amino acid leucine, 2) regular whey protein concentrate 80 (WPC-80) and 3) regular milk. Three acute and two long-term training studies were conducted. In total 77 young and 60 elderly men and women took part in the studies. The primary endpoints of the thesis are changes in muscle protein synthesis (acute studies) and changes in lean muscle mass (training studies). Secondary endpoints are changes in quadriceps cross sectional area, m. vastus lateralis thickness, muscle fiber cross sectional area, muscle function measured as maximal tests (1RM) and functional test (only in elderly), and phosphorylation of central kinases involved in the regulation of muscle protein synthesis (p70S6K, 4EBP1 and eEF-2).Paper I: Hamarsland H, Laahne JAL, Paulsen G, Cotter M, Borsheim E, Raastad T. Native whey induces higher and faster leucinemia than other whey protein supplements and milk: a randomized controlled trial. BMC Nutrition 2017 3:1. BioMed Central; 2017;3:10.Paper II: Hamarsland H, Nordengen AL, Aas SN, Kristin Holte, Ina Garthe, Gøran Paulsen, Matthew Cotter, Elisabet Børsheim, Benestad HB, Raastad T. Native whey protein with high levels of leucine results in similar post-exercise muscular anabolic responses as regular whey protein, in young individuals. In review.Paper III: Hamarsland H, Aas SN, Nordengen AL, Kristin Holte, Ina Garthe, Gøran Paulsen, Matthew Cotter, Elisabet Børsheim, Benestad HB, Raastad T. Native whey induces similar post exercise muscle anabolic responses as regular whey, despite greater leucinemia, in elderly individuals. Submitted. Tatt ut av filen i Brage p.g.a. copyright-restriksjoner. / Not in the file in Brage because of copyright issues.Paper IV: Hamarsland H, Handegard V, Kåshagen M, Benestad HB, Raastad T. Native whey with high levels of leucine induces similar adaptation to strength training as milk protein, in young individuals. Manuscript. Tatt ut av filen i Brage p.g.a. copyright-restriksjoner. / Not in the file in Brage because of copyright issues.Paper V: Hamarsland H, Johansen MK, Seeberg F, Brochmann M, Garthe I, Benestad HB, Raastad T. Native whey induces similar adaptation to strength training as milk protein, despite higher levels of leucine, in elderly individuals. Manuscript. Tatt ut av filen i Brage p.g.a. copyright-restriksjoner. / Not in the file in Brage because of copyright issues.
Avhandling (doktorgrad) - Norges idrettshøgskole, 2017