Treningsforum

Enda en liten spiker i kisten til raske karbohydrater etter styrketrening.


Muscle Protein Breakdown has a Minor Role in the Protein Anabolic Response to Essential Amino Acid and Carbohydrate Intake Following Resistance Exercise.

Am J Physiol Regul Integr Comp Physiol. 2010 Jun 2.

Glynn EL, Fry CS, Drummond MJ, Dreyer HC, Dhanani S, Volpi E, Rasmussen BB.


Muscle protein breakdown (MPB) is increased following resistance exercise (RE), but ingestion of carbohydrate (CHO) during post-exercise recovery can decrease MPB with no affect on muscle protein synthesis (MPS). We sought to determine if a combination of essential amino acids (EAA) with low CHO (LCHO), or high CHO (HCHO) could effectively reduce MPB following RE and improve muscle protein net balance (NB). We hypothesized higher levels of CHO and resulting increases in circulating insulin would inhibit MPB and associated signaling, resulting in augmented NB. Thirteen male subjects were assigned to one of two groups receiving equivalent amounts of EAA (~20g) but differing CHO (LCHO=30, HCHO=90g). Groups ingested nutrients 1 hour after an acute bout of leg RE. Leg phenylalanine kinetics (e.g., MPB, MPS, NB), signaling proteins and mRNA expression were assessed on successive muscle biopsies using stable isotopic techniques, immunoblotting, and real-time qPCR respectively. MPB tended to decrease (P<0.1) and MPS increased (P<0.05) similarly in both groups following nutrient ingestion. No group differences were observed, but MuRF1 (muscle RING finger 1) protein content and MURF1 mRNA expression increased following RE and remained elevated following nutrient ingestion, while autophagy marker, light chain 3B (LC3B-II), decreased after nutrient ingestion (P<0.05). FOXO3a phosphorylation, total muscle atrophy F-box (MAFbx) protein, MAFbx and caspase-3 (CASP3) mRNA expression were unchanged. We conclude the enhanced muscle protein anabolic response detected when EAA+CHO are ingested post-RE is primarily due to an increase in MPS with minor changes in MPB, irrespective of CHO dose or circulating insulin level.

http://www.ncbi.nlm.nih.gov/pubmed/20519362 (http://www.ncbi.nlm.nih.gov/pubmed/20519362)

Interessant.
Jeg er godt i gang med Lyle McDonals "the protein book". Hvor han i et avsnitt nevner at insulin har effekt på muskelproteinyntesen, men i en veldig liten grad. Dog hevder han at insulin kan spille en større rolle i å redusere proteinnedbrytning. Han refererer til studien:

 "Diabetes Metab Rev.  1989 Mar;5(2):165-89.
Influence of nutrient intake on protein turnover.
McNurlan MA, Garlick PJ."

Men dessverre har jeg ikke tilgang til denne på Pubmed.

Kjenner du til lignende studier hvor en av testgruppene bare tar protein og ikke karbs? (Det må da finnes). Kanskje matproteiner i seg selv hever insulinnivåene nok til å øke proteinsyntesen og minke proteinnedbrytningen...?

http://www.treningsforum.no/forum/index.php?topic=59088.0 (http://www.treningsforum.no/forum/index.php?topic=59088.0)


At insulinnivåene ikke trenger å være særlig mye høyere enn straks over fastenivå for maksimal proteinsyntese er et veletablert faktum:

http://www.treningsforum.no/forum/index.php?topic=96936.msg1451525#msg1451525 (http://www.treningsforum.no/forum/index.php?topic=96936.msg1451525#msg1451525)

(dog stimulerer insulin proteinsyntesen ved injisering av mengder som er langt større (1000ggr) enn hva kroppene våre klarer å produsere naturlig).

Det er kun proteinnedbrytningen insulin har en litt mer mengderelatert virkning på, men dette ikke noe man trenger å tenke over. Den ordner seg selv og er heller ikke en stor faktor i sammenligning med proteinsyntesen.


Mer her:
http://www.treningsforum.no/forum/index.php?topic=96936.msg1452159#msg1452159 (http://www.treningsforum.no/forum/index.php?topic=96936.msg1452159#msg1452159)