Ny studie om proteinsyntesen

Etter ca 48 timer (2 døgn) er den nesten tilbake til utgangspunktet og utover 3 døgn er det primært strukturelle reparasjoner som er aktive. Denne studien viser effekten av den såkalte Repeated Bout Effect (RBE), som sier at regelmessig trening har en beskyttende effekt på muskelen, og responsen etter ei treningsøkt blir stadig mindre og mer kortvarig. Studien gikk over 8 uker, og forsøkspersonene trente det ene beinet med beinspark (leg extension) mens det andre beinet fungerte som kontroll og ble ikke trent. Treningsprogrammet var som følger:

Beinspark 3x pr uke

Uke 1-2: 3 sett 10-12 reps

Uke 3-4: 4 sett 8-10 reps

Uke 5-6: 5 sett 8-10 reps

Uke 7-8: 6 sett 6-8 reps

Proteinsyntesen økte i begge beina (det skjer systemisk), men økte mest i beinet som ble trent. Muskelmassen økte kun i det trente beinet. Etter 8 uker så man at proteinsyntesen var tilbake til null etter bare 28 timer i det trente beinet (altså litt over ett døgn), men i det utrente beinet var proteinsyntesen fremdeles økt med 70 +/- 49% (altså opptil 120%).

Dette gjør det bare enda mer tydelig at man ikke må ofre treningsfrekvensen - å trene hver muskel en gang per uke blir for sjelden og man kan ikke kompensere ved å kjøre 20-30 sett heller, det gir liten eller ingen additiv effekt når man har nådd et visst minimum.

Jeg har i åresvis anbefalt viderekomne og avanserte løftere at man minst trener hver muskelgruppe hver 5. dag, og helst to, opptil tre ganger i uka - da vil man også kunne trene både med et passe volum og følge en regelmessig belastningsprogresjon. Denne treningsfrekvensen finner man igjen i effektive treningsprogrammer som HST, DC og 5x5.
 

Am J Physiol Regul Integr Comp Physiol. 2007 Nov 21

Resistance training alters the response of fed-state mixed muscle protein synthesis in young men.

Tang JE, Perco JG, Moore DR, Wilkinson SB, Phillips SM.

Kinesiology, McMaster University, Hamilton, Canada.

Ten healthy young men (21.0 +/- 1.5 yr, 1.79 +/- 0.1 m, 82.7 +/- 14.7 kg, mean +/- SD) participated in eight weeks of intense unilateral resistance training (knee extension exercise) such that one leg was trained (T) and the other acted as an untrained (UT) control. After the eight weeks of training, infusions of L-[ring-d5] phenylalanine, L-[ring-(13)C6] phenylalanine, and d3 alpha-KIC were used to measure mixed muscle protein synthesis in the T and UT legs by the direct incorporation method (FSR). Protein synthesis was determined at rest, 4 and 28 h after an acute bout of resistance exercise performed at the same intensity relative to the gain in strength before and after training. Training increased mean muscle fibre cross-sectional area only in the T leg (type I: 16 +/- 10 %; type II: 20 +/- 19 %, P < 0.05). Muscle protein FSR in both legs at 4 h (T: 162 +/- 76 %; UT: 108 +/- 62 %, P < 0.01 versus rest) with the increase in the T leg being significantly higher than in the UT leg at this time (P < 0.01). At 28 h post-exercise, FSR in the T leg had returned to resting levels; however, the rate of protein synthesis in the UT leg remained elevated above resting (70 +/- 49%, P < 0.01). We conclude that resistance training attenuates the protein synthetic response to acute resistance exercise, despite higher initial increases in FSR, by shortening the duration for which protein synthesis is elevated. 

Fra studien:

The leg to be trained was selected randomly, counter-balanced for dominance based on strength, such that equal numbers of subjects trained their dominant and non-dominant legs. Training was performed 3 d·wk-1 (Monday to Friday) initially (weeks 1-4) and then only 2 d·wk-1 at the latter stages of the training (weeks 5-8); at least one day of rest was provided between each training session. For weeks 1-2, training began with three sets of knee extension exercise performed at a workload equivalent to each subject's 10-12 RM. For weeks 3-4, participants performed four sets at their 8-10 RM. The number of sets was increased to five for weeks 5-6. Finally, for weeks 7-8 participants performed six sets at a workload equivalent to their 6-8 RM.

Børge A. Fagerli

Coach MyoRevolution Team

borge@myorevolution.com