Monday, July 28, 2014

Accelerated Satellite (= Muscle Precursor) Cell Proliferation is Yet Another Way for Whey to Promote Muscle Gains

When the satellite cells merge with the existing muscle cells to form new myonuclei this is more than muscle repair, it's also the foundation for future muscle growth - beyond previous limits | more
If you've read the Intermittent Thoughts On Building Muscle (read it) you are beyond the simplistic view of muscle growth as a one-way process in the course of which muscle cells balloon up endlessly. Without the incorporation of "new" myonuclei (cell kernels) from the periphery your muscle would become dysfunctional sooner or later (learn more); and while myostatin will prevent that from happening the recruitment of new muscle cells from the satellite cell pool will provide the basis for future muscle growth.

I don't want to go into more detail, here. If you want to develop a better understanding of this process(es), I suggest you head back to the initially mentioned series about the physiological underpinnings of skeletal muscle hypertrophy.
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Next to the inclusion of new myonuclei and facilitation of future muscle growth, the satellite cell pool will also provide the raw material for the repair or I should say replacement of damaged muscle cells. For strength trainees like you and me, it's thus of paramount importance to ensure that our satellite cells are happy and healthy. And you know what? That's not even difficult!

According to a recent study from the Aarhus University all it takes to  help your muscle precursor cells happily proliferating (grow, divide and mature to "real" muscle cells) is the mix of carbohydrates and whey protein you're probably consuming after each workout, anyway: A shake containing 28 g whey protein hydrolysate high in leucine (4 %) an 28 g of carbohydrate (4 %) - a 56h carbohydrate supplement served as control.
Figure 1: Overview of the experimental procedure (Farup. 2014)
As you can see in Figure 1 this supplement was not ingested once, but rather thrice a day - with the first serving being ingested immediately after the fasted subjects, 24 healthy young recreational active men,  initiated the exercise protocol, which lasted for approximately 30 min.

It's the whey that does the trick, but we don't know if we don't need CHOs as an adjunct

The provision of extra whey protein (but nor carbohydrates; white bars in Figure 2) lead to significant increases in satellite cell activity in both mixed muscle and type II fibers, but not type I fibers (not shown in Figure 2).
Figure 2: Number of satellite cells per muscle fiber (higher number = higher chance of incorporation; Farup. 2014)
Still, in view of the fact that regeneration is an energetically costly process, it's not 100% certain that a certain amount of carbohydrates may be necessary to see the beneficial effects on satellite cell activity and the changes in maximal voluntary contraction force (not shown).
High volume increases satellite cell activity, as well | read more
Bottom line: I know that you don't really need another reason to supplement with whey protein. I am also aware that the result, as new as they may be, will not make whey protein more efficient that it already is.

What I would like to know, though, is whether there are hormonal changes involved, as well. What about IGF-1, for example? As you've read in the initially cited series about building muscle, the latter, or rather its splice variants, appear heavily involved in the structural super-compensation effects that facilitate future gains in skeletal muscle mass. Or whether the effects of whey isolate, concentrate and hydrolysate (used in the study) differ (if it's IGF, hydrolysate should be most potent, because it's most insulinogenic).

Alas, I guess, we will have to wait for future studies to elucidate these "secrets", in the mean time, I will stick to my whey isolate + concentrate mixes. Why? Well, money and taste are worth considering, as well... especially if you guesstimate the advantage of the bad tasting highly expensive hydrolysate to be as negligible, as I do.
Reference:
  • Farup, et al. "Whey protein supplementation accelerates satellite cell proliferation during recovery from eccentric exercise." Amino Acids (2014). Ahead of print.