Bodybuilder Nutrition Roundtable
By Josh Beaty
The following interview was conducted by Josh Beaty with Layne Norton, Jamie Hale, Alan Aragon and Will Brink. Sit back and enjoy a very informative discussion.
J Beaty: The big focus in hypertrophy research lately has the mtor pathway. What impact does this research have on bodybuilders?
L Norton: The mTOR pathway is a major cellular anabolic pathway that is responsible for much of the anabolic response to nutrient stimulus. In adult subjects, amino acids (specifically leucine) are responsible for triggering mTOR activation. mTOR essentially acts as a 'leucine gage.' If leucine levels increase, mTOR becomes active & activates other components of the protein synthetic pathway because it high leucine levels indicate a fed state and ample amino acids are present for protein synthesis to occur. If leucine levels drop, mTOR becomes less active as it senses that there are not enough amino acids & energy to continue protein synthesis. mTOR is also sensitive to total energy intake and if total energy drops too low, then mTOR becomes less activated. This research indicates what many bodybuilders have known for sometime: if you're goal is to build muscle mass, make sure you provide a diet with ample calories and ample amino acids.
W Brink: I'm not going to have a great response to this question as it's really not my area of focus or expertise. As far as I know, there is no practical application of the mTOR pathway to athletes at this time. That is to say, I don't know of any particular change an athlete can make to their approach that will profoundly alter this pathway to give any advantages. It may also simply be that the approach we know is optimal for strength and or LBM - loading, volume, tempos, etc - are already the best we can do as far influencing mTOR is concerned. Like so many areas of research that may have applications to wasting diseases and such, such as myostatin, it's more of an intellectual exercise versus having any real practical application to athletes at this time, non pharmacologically speaking at least. There is no doubt that the intensive research going on that examines the signaling events that are activated by aerobics or resistance training will explain how muscle adaptations take place, and pharmaceutical interventions are a focus of many researchers, but I am unaware of any direct application an athlete can incorporate in their training or diet that will be an improvement on what we already know. The other guests on this roundtable may be more up to date on the literature and have a better answer! I'm a bit jaded at this point in that I don't get particularly excited or interested in the latest holy grail of signaling molecules until some real practical application shows itself.
J Hale: The mammalian target of rapamycin (mTOR) is a serine/threonine kinase that plays a key role in anabolism. MTOR stimulates cell growth by phosphorylating p70 ribosomal S6 kinase (S6K) and eukaryote initiation factor 4E-binding protein 1 (4EBP1). mTor is stimulated by resistance training, insulin and Leucine (bcaa). When mentioning mtor pathway it is probably necessary to mention there are also other kinases that inhibit anabolism when activated. In particularly I am referring to the Ampk/ Akt mtor switch. Basically when Ampk is elevated protein synthesis is inhibited. Ampk (5 Amp-activated protein kinase) is a heterotimeric serine/ threonine kinase. Ampk is often referred to as a cellular fuel gauge. Ampk is activated by endurance exercise, elevated levels of cellular AMP, hypoxia, glucose deprivation and ischemia. When Ampk is elevated cellular fuel regenaration is top priority, while pathways the consume energy are inhibited (ex: protein synthesis). This applies to athletes as we know various conditions stimulate these pathways. By optimizing stimulation of anabolic pathways and minimizing catabolic pathways (intensity and duration of) we obviously optimize performance and physique benefits. Does t his really tell us any more than we already knew (proper resistance, protein intake and sufficient cals maximize growth)? For myself and other practical scientists I feel like this info is very helpful with enhancing our knowledge of what's going on at a cellular level. It also helps with program design and recognizing at a molecular level factors that affect anabolic and catabolic pathways. As far as the typical bodybuilder or trainee is concerned knowledge of mtor pathway may or may not be beneficial. Depends on bodybuilder and how serious he is about furthering his knowledge concerning physique and performance.
A little off the subject alcohol intoxication has also been shown inhibit mtor pathway. Studies involving mtor pathway also are important in treating muscle wasting disease.
A Aragon: First off, I'd like to thank Jamie for inviting me to this roundtable. It's definitely an honor to be among a carefully chosen few. If I come off too long-winded in this, it's because I made Jamie wait for months for me to participate, so I figured I might as well show some gratitude and babble for aeons
Ah, the good ol' phosphatidylinositol 3-kinase-mammalian target rapamycin signaling pathway. There, that should take care of any lack of technical jargon I contribute to this roundtable right off the bat. mTOR research is not likely to have a significant impact on the furthering of what bodybuilders can physically achieve, but it certainly is giving us some understanding of how these achievements occur. Let's face it, the majority of the biggest, most ripped guys on the planet haven't even heard of mTOR.