|Who says, resistance training and high protein diets make you bulky? The study at hand suggest they don't because after a couple of weeks your body will pull the myostatin break | img (c) fighterdiet.com|
While previous studies mostly suggested that the role of myostatin in the normal (muscle) growth response to exercise may have been overestimated, a recent study from the University of Padova, the Italian Medicine and Fitness Federation, Euganea Medica, and the University of Palermo. Brings the "muscle-growth break" (high myostatin = slow muscle gains) back onto our radar. And that not just because researchers from said institutions observed a significant increase in myostatin in response to chronic resistance training, but rather because this response appears to have been triggered by high(er) protein intakes.
If you have been reading SuppVersity articles for quite a while now, you may remember my previous post about how "Chronic Resistance Training Reduces the Anabolic Signaling in Response to Exercise - 12 Days of Detraining Restore It" (read more). The corresponding study by Ogasawara et al. (2013) was yet conducted on rodents. Therefore, the applicability of the results remains at least questionable.
In a more recent study with human subjects, Antonio Paoli and colleagues from Italy did yet observe a similar, but not identical effect. The researchers aim was to "investigate the influence of 2 months of resistance training (RT) and diets with different protein contents on plasma myostatin (MSTN), interleukin 1 beta (IL-1β), interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-α), and insulin-like growth factor 1 (IGF-1).
Does an increase in protein intake increase myostatin, as well?
To this ends, they recruited 18 healthy, young, physically active volunteers who were then randomly divided in two groups; A high protein (HP) and normal protein (NP) groups. The diets contained 1.8 and 0.85 g of protein/kg body weight per day for the HP and NP diet, respectively.
In addition to the dietary intervention, all subjects were subjected to the same 8 weeks of standardized progressive resistance training. MSTN, IGF-1, IL-1β, IL-6, and TNF-α were analyzed before and after the first and the last training sessions. In addition, Paoli et al. measured the lean body mass, muscle mass, upper-limb muscle area, and strength.
|Figure 1: Much to the surprise of the researchers, the muscle gains were identical, but the msucle gain reducing myostatin increase was significant only in the high protein group (Paoli. 2014)|
|Protein blunts the exercise induced decrease in myostatin, but it increases the alleged myostatin blocker FLRG (Hulmi. 2008) - Result? A null or maybe even beneficial effect?|
Is this just a matter of domain sizes?
|Figure 2: Domain sizes of EDL and soleus muscle fibers in wild-type control, myostatin negative and IGF1 over-expressing mice (data based on Qaisar. 2011)|
Without myostatin, the domain sizes would keep increasing and the muscle would become as huge, but dysfunctional as it does in myostatin negative mice (see Figure 2, red | not the similar increase in domain size in IGF-1(+) mice which underlines the role both myostatin and IGF-1 play when it comes to controlling domain sizes and facilitating "Getting Big Beyond Temporary Physiological Limits" | learn more)
The way it is, the observations Paoli et al. made in their most recent study remain, as the authors themselves call it "paradoxical" and could in fact "explain the substantial overlapping of MM [muscle mass] increases in the two groups", no one of you would have expected, right? Well, it's a pitty we don't have data on the level of follistatin related gene expression as it was measured in the Hulmi study (see red box) - if that did not increase, or only to a small extend, it's actually no wonder, both groups gained the same amount of muscle mass.
- Hill, Jennifer J., et al. "The myostatin propeptide and the follistatin-related gene are inhibitory binding proteins of myostatin in normal serum." Journal of Biological Chemistry 277.43 (2002): 40735-40741.
- Hulmi, Juha J., et al. "The effects of whey protein on myostatin and cell cycle-related gene expression responses to a single heavy resistance exercise bout in trained older men." European journal of applied physiology 102.2 (2008): 205-213.
- Paoli, et al. "Protein Supplementation Increases Postexercise Plasma Myostatin Concentration After 8 Weeks of Resistance Training in Young Physically Active Subjects." J Med Food. Aug 18 (2014). Epub ahead of print.
- Qaisar, Rizwan, et al. "Is functional hypertrophy and specific force coupled with the addition of myonuclei at the single muscle fiber level?." The FASEB Journal 26.3 (2012): 1077-1085.
- Roth, Stephen M., et al. "Ultrastructural muscle damage in young vs. older men after high-volume, heavy-resistance strength training." Journal of Applied Physiology 86.6 (1999): 1833-1840.
- Roth, Stephen M., et al. "Myostatin gene expression is reduced in humans with heavy-resistance strength training: a brief communication." Experimental Biology and Medicine 228.6 (2003): 706-709.
- Willoughby, Darryn S. "Effects of heavy resistance training on myostatin mRNA and protein expression." Medicine and science in sports and exercise 36.4 (2004): 574-582.