King Grub
2017-03-13, 08:43
Styrketräning både ökar muskeluppbyggnaden och minskar muskelnedbrytningen i vila, inte bara åstadkommer en akut stimulans av proteinsyntesen timmarna efter ett pass. Efter 12 veckors träning är fastande muskelproteinsyntes i vila 24 % högre och fastande muskelproteinnedbrytning 21 % lägre än hos icke tränande.
Samtidigt såg man att övrig proteinnedbrytning ökade hos tränande, dvs antagligen prioriterades muskelmassa framför organmassa som resultat av träningen. Mer av aminosyrorna som frisätts från proteinnedbrytning byggs in som nytt muskelprotein hos tränande.
Man vet sedan tidigare att proteinsyntes skapad av styrketräning bara får en koppling till hypertrofi på sikt, när man även tagit hänsyn till nedbrytningen:
http://onlinelibrary.wiley.com/wol1/doi/10.1113/JP272472/abstract
Högre träningsfrekvens skulle alltså inte behöva vara bäst för hypertrofi, eftersom den akuta proteinsyntesen inte har den kopplingen till hypertrofi. Hypertrofi kanske främst i stället är kopplad till cellulära anpassningar som modifierar proteinomsättningen till att både bygga mer muskler och bryta ned mindre muskler hela tiden, i vila och i fastande tillstånd, och dessa förändringar kanske i stället påverkas mer av träningsvolym vid enstaka tillfällen.
PURPOSE:
Acute bouts of resistance exercise and subsequent training alters protein turnover in skeletal muscle. The mechanisms responsible for the changes in basal post-absorptive protein turnover and its impact on muscle hypertrophy following resistance exercise training are unknown. Our goal was to determine whether post-absorptive muscle protein turnover following 12 weeks of resistance exercise training (RET) plays a role in muscle hypertrophy. In addition, we were interested in determining potential molecular mechanisms responsible for altering post-training muscle protein turnover.
METHODS:
Healthy young men (n = 31) participated in supervised whole body progressive RET at 60-80% 1 repetition maximum (1-RM), 3 days/week for 3 months. Pre- and post-training vastus lateralis muscle biopsies and blood samples taken during an infusion of 13C6 and 15N phenylalanine and were used to assess skeletal muscle protein turnover in the post-absorptive state. Lean body mass (LBM), muscle strength (determined by dynamometry), vastus lateralis muscle thickness (MT), myofiber type-specific cross-sectional area (CSA), and mRNA were assessed pre- and post-RET.
RESULTS:
RET increased strength (12-40%), LBM (~5%), MT (~15%) and myofiber CSA (~20%) (p < 0.05). Muscle protein synthesis (MPS) increased 24% while muscle protein breakdown (MPB) decreased 21%, respectively. These changes in protein turnover resulted in an improved net muscle protein balance in the basal state following RET. Further, the change in basal MPS is positively associated (r = 0.555, p = 0.003) with the change in muscle thickness.
CONCLUSION:
Post-absorptive muscle protein turnover is associated with muscle hypertrophy during resistance exercise training.
Eur J Appl Physiol. 2017 Mar 9. Post-absorptive muscle protein turnover affects resistance training hypertrophy.
https://link.springer.com/article/10.1007%2Fs00421-017-3566-4
Samtidigt såg man att övrig proteinnedbrytning ökade hos tränande, dvs antagligen prioriterades muskelmassa framför organmassa som resultat av träningen. Mer av aminosyrorna som frisätts från proteinnedbrytning byggs in som nytt muskelprotein hos tränande.
Man vet sedan tidigare att proteinsyntes skapad av styrketräning bara får en koppling till hypertrofi på sikt, när man även tagit hänsyn till nedbrytningen:
http://onlinelibrary.wiley.com/wol1/doi/10.1113/JP272472/abstract
Högre träningsfrekvens skulle alltså inte behöva vara bäst för hypertrofi, eftersom den akuta proteinsyntesen inte har den kopplingen till hypertrofi. Hypertrofi kanske främst i stället är kopplad till cellulära anpassningar som modifierar proteinomsättningen till att både bygga mer muskler och bryta ned mindre muskler hela tiden, i vila och i fastande tillstånd, och dessa förändringar kanske i stället påverkas mer av träningsvolym vid enstaka tillfällen.
PURPOSE:
Acute bouts of resistance exercise and subsequent training alters protein turnover in skeletal muscle. The mechanisms responsible for the changes in basal post-absorptive protein turnover and its impact on muscle hypertrophy following resistance exercise training are unknown. Our goal was to determine whether post-absorptive muscle protein turnover following 12 weeks of resistance exercise training (RET) plays a role in muscle hypertrophy. In addition, we were interested in determining potential molecular mechanisms responsible for altering post-training muscle protein turnover.
METHODS:
Healthy young men (n = 31) participated in supervised whole body progressive RET at 60-80% 1 repetition maximum (1-RM), 3 days/week for 3 months. Pre- and post-training vastus lateralis muscle biopsies and blood samples taken during an infusion of 13C6 and 15N phenylalanine and were used to assess skeletal muscle protein turnover in the post-absorptive state. Lean body mass (LBM), muscle strength (determined by dynamometry), vastus lateralis muscle thickness (MT), myofiber type-specific cross-sectional area (CSA), and mRNA were assessed pre- and post-RET.
RESULTS:
RET increased strength (12-40%), LBM (~5%), MT (~15%) and myofiber CSA (~20%) (p < 0.05). Muscle protein synthesis (MPS) increased 24% while muscle protein breakdown (MPB) decreased 21%, respectively. These changes in protein turnover resulted in an improved net muscle protein balance in the basal state following RET. Further, the change in basal MPS is positively associated (r = 0.555, p = 0.003) with the change in muscle thickness.
CONCLUSION:
Post-absorptive muscle protein turnover is associated with muscle hypertrophy during resistance exercise training.
Eur J Appl Physiol. 2017 Mar 9. Post-absorptive muscle protein turnover affects resistance training hypertrophy.
https://link.springer.com/article/10.1007%2Fs00421-017-3566-4