Maybe of interest?
In short, the workers used low intensity resistance exercise (in resistance-trained subjects) and studied how using a prolonged time under tension affected the synthesis of myofibrillar (contractile proteins), mitochondrial (energy producing), and sarcoplasmic (transport and cell signalling proteins, glycolysis, etc.) proteins.
These data suggest that using a prolonged time under tension shifts the signals to turn on mitochondrial and sarcoplasmic proteins, as opposed to myofibrillar proteins (what we need to build to produce serious mass and strength). They also highlight the importance of exercise volume, not simply recruiting muscle fibres, in stimulating myofibrillar protein synthesis (i.e. muscle building).
An interesting result in this study is that a carryover effect, of the previous resistance exercise session, existed on potentiated the feeding-mediated response 24 h later. These data highlight the value of postexercise protein consumption, not only immediate after resistance exercise, but also 24 hours later (R.E. drink your morning protein shake).
Published in the Journal of Physiology
Muscle time under tension during resistance exercise stimulates differential muscle protein sub-fractional synthetic responses in men
We aimed to determine if the time that muscle is under loaded tension during low intensity resistance exercise affects the synthesis of specific muscle protein fractions or phosphorylation of anabolic signalling proteins. Eight men (24Â±1 y, BMI= 26.5Â±1.0 kgâ??m-2) performed 3 sets of unilateral knee extension exercise at 30% of 1-repetition maximum strength involving concentric and eccentric actions that were 6 sec in duration to failure (SLOW) or a work-matched bout that consisted of concentric and eccentric actions that were 1 sec in duration (CTL).
Participants ingested 20 g of whey protein immediately after exercise and again at 24 h recovery. Needle biopsies (vastus lateralis) were obtained while fasted at rest and after 6, 24, and 30 h post-exercise in the fed-state following a primed, constant infusion of L-[ring-13C6]phenylalanine. Myofibrillar protein synthetic rate was higher in SLOW condition versus CTL after 24-30 h recovery (P<0.001) and correlated to p70S6K phosphorylation (r=0.42, p=0.02).
Exercise-induced rates of mitochondrial and sarcoplasmic protein synthesis were elevated by 114% and 77%, respectively, above rest at 0-6 h post-exercise only in the SLOW condition (both P<0.05). Mitochondrial protein synthesis rates were elevated above rest during 24-30 h recovery in the SLOW (175%) and CTL (126%) conditions (both P<0.05). Lastly, muscle PGC-1Î± expression was increased at 6 h post-exercise compared to rest with no difference between conditions (main effect for time, P<0.001).
These data show that greater muscle time under tension increased the acute amplitude of mitochondrial and sarcoplasmic protein synthesis and also resulted in a robust, but delayed stimulation of myofibrillar protein synthesis 24-30 h after resistance exercise.