Odgovor Če feb 22, 2018 06:21

Arachidonic Acid: Weightlifting Study

Arachidonic Acid: Weightlifting Study

It has been a hot couple of months for the study of arachidonic acid, principle representative of the omega-6 family. On the heels of a recent study showing its supplementation to increase the expression of myogenin and MyoD, another paper has been published looking at its role in the underlying mechanisms of hypertrophy (1). This is the 4th study of ARA supplementation by weightlifters, and also the 4th to produce favorable findings either with regard to ergogenic effect, body composition, or markers of muscle growth. A quick review of this study and its main findings is found below. Again, full disclosure, my company introduced the first ARA supplement (X-FACTOR™) back in 2003, and funded the first two human trials. However, we were not involved in this latest (or previous) study.
Study Design:

This investigation involved 19 young active male participants. The men were divided into two groups, each with an average age of 24.6 and 26.4 years. As part of the inclusion criteria, the subjects exercised regularly, with a least one-year of prior resistance training. One group was given 1,500 mg of arachidonic acid per day for 4 weeks, and the other, an identical-looking placebo. Both at baseline and the conclusion of the study, the men were subject to a series of blood tests and muscle biopsies, which measured acute protein synthesis and anabolic signaling for up to 4 hours post exercise, as well as ribosome biosynthesis and satellite cell counts at 48 hours. They found two key effects of ARA supplementation.
Ribosome Biogenesis

The ribosomes are the main effectors of protein synthesis within our cells. These tiny machines are responsible for assembling amino acids into complex proteins. Similarly, their abundance is a direct determinant of our cells’ translational capacity, or total ability to synthesize proteins. Resistance training has been shown to stimulate ribosome biogenesis. This increase in ribosome content appears to be a basic structural adaptation necessary for ongoing muscle hypertrophy (2). With this in mind, we regard ribosome biogenesis as an important regulator of skeletal muscle mass. The researchers in this study found arachidonic acid supplementation to significantly stimulate this process.

“In contrast to placebo, expression of 45S pre-rRNA was increased at 48 h post exercise in the ARA group, by all three independent primer sets (5’ETS, ITS+5.8S, ITS+28S)… Moreover, ARA supplementation increased muscle UBF protein levels suggesting that ARA supplementation may enhance ribosome biogenesis via increased expression of components of the pre-initiation complex (PIC), leading to increased capacity for Polymerase I activity.”

Satellite Cells

Another important structural adaptation in response to resistance training is myonuclear accretion (3). This is the process in which the content of nuclei is increased within our skeletal muscle cells. Myonuclear accretion helps support/improve the operating efficiency of these cells, which could otherwise be impaired with expansion, to the detriment of protein synthesis and further growth. These nuclei are provided by satellite cells. Likewise, the abundance of satellite cells can be another key determinant of hypertrophy. Arachidonic acid supplementation also appears to have a beneficial effect here. The paper explains, as follows.

“Satellite cells play an important role in repair of damaged muscle, tissue remodeling and may be regulate extreme muscle hypertrophy. In the present study, the number of cells in muscle staining positive for the satellite cell marker NCAM was increased hours after exercise in both groups. However, there was a tendency for a greater percentage increase in NCAM+ cells in the ARA group (84%) compared with placebo (16%). NCAM mRNA expression also tended to increase to a greater extent in the ARA group than placebo at 2 hours after exercise. Additionally, mRNA expression of the satellite cell marker PAX7 was greater in the ARA group compared with placebo at 48 hours after exercise. “


Summary:

We often view protein synthesis as the defining metric when it comes to muscle growth. In many regards, it is. However, ongoing muscle hypertrophy also involves adaptations to skeletal muscle cell structures that influence the capacity for, and efficiency of, protein synthesis. These adaptations will determine how much and how fast we can ultimately grow. As we’ve found in this latest study, arachidonic acid appears to have a strong impact in two very important areas: satellite cell proliferation and ribosome biogenesis. More research is warranted to further examine the role of ARA in muscle growth, of course. However, after 4 published placebo-controlled trials, we are starting to see a clearer picture. This nutrient, once completely ignored by sports scientists, appears to be quite necessary for the process, and may be an effective tool for improved performance.
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