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-   -   Blood Flow Restriction during Low-Intensity Resistance Exercise Increases S6K1 Phosphorylation and Muscle Protein Synthesis. (http://www.abcbodybuilding.com/forums/showthread.php?t=86302)

Fahsy 07-17-2007 03:18 PM

Blood Flow Restriction during Low-Intensity Resistance Exercise Increases S6K1 Phosphorylation and Muscle Protein Synthesis.
 
http://jap.physiology.org/cgi/reprint/00195.2007v1

J Appl Physiol. 2007 Jun 14

Blood Flow Restriction during Low-Intensity Resistance Exercise Increases S6K1 Phosphorylation and Muscle Protein Synthesis.

Fujita S, Abe T, Drummond MJ, Cadenas JG, Dreyer HC, Sato Y, Volpi E, Rasmussen BB.

Internal Medicine, University of Texas Medical Branch, Galveston, Texas, United States; Human and Engineered Environment, Graduate School of Frontier Sciences, University of Tokyo, Tokyo, Texas, Japan.

Low-intensity resistance exercise training combined with blood flow restriction (REFR) increases muscle size and strength as much as conventional resistance exercise with high-loads. However, the cellular mechanism(s) underlying the hypertrophy and strength gains induced by REFR are unknown. We have recently shown that the mTOR signaling pathway is involved in the increase in muscle protein synthesis after an acute bout of high-intensity resistance exercise in humans. Therefore, we hypothesized that an acute bout of REFR would enhance mTOR signaling and stimulate muscle protein synthesis (MPS). We measured MPS and phosphorylation status of mTOR-associated signaling proteins in 6 young male subjects. Subjects were studied once during blood flow restriction (REFR, bilateral leg extension exercise at 20% of 1-RM while a pressure cuff was placed on the proximal end of both thighs and inflated at 200mmHg) and a second time using the same exercise protocol but without the pressure cuff (CTRL). MPS in the vastus lateralis muscle was measured by using stable isotope techniques and the phosphorylation status of signaling proteins were determined by immunoblotting. Blood lactate, cortisol, and growth hormone were higher following REFR as compared to CTRL (P<0.05). S6K1 phosphorylation, a downstream target of mTOR, increased concurrently with a decreased eEF2 phosphorylation and a 46% increase in MPS following REFR (P<0.05). MPS and S6K1 phosphorylation were unchanged in the CTRL group post-exercise. We conclude that the activation of the mTOR signaling pathway appears to be an important cellular mechanism which may help explain the enhanced muscle protein synthesis during REFR. Key words: mTOR , ischemia, hypertrophy, protein metabolism, post-exercise recovery.


This is another interesting paper showing the mechanism behind why occlusion can stimulate hypertrophy. A stronger paper compared to the other paper I posted from EJAP.

Venom 07-21-2007 04:22 AM

Re: Blood Flow Restriction during Low-Intensity Resistance Exercise Increases S6K1 Phosphorylation and Muscle Protein Synthesis.
 
Whats really interesting to me, is that a lot of studies on protein synthesis attribute the increase in protein synthesis to enhanced blood flow (and particularly extracellular amino acid delivery). And off course, bodybuilders have always been huge on training to the "pump."

So would this support static contraction techniques as well?

Fahsy 07-21-2007 02:07 PM

Re: Blood Flow Restriction during Low-Intensity Resistance Exercise Increases S6K1 Phosphorylation and Muscle Protein Synthesis.
 
That's a great point. It is possible that the reactive hyperemia that occurs after occulsion allows for greater neutrient delivery. It would be intersting to perform a study involving a glucose challenge test and occulusion to see if the occulusion improves glucose uptake.

Not sure about the static contraction technique- would you say blood flow is restricted during a staic contraction?

Venom 07-21-2007 04:45 PM

Re: Blood Flow Restriction during Low-Intensity Resistance Exercise Increases S6K1 Phosphorylation and Muscle Protein Synthesis.
 
Yup, I would definitely say it is.

Fahsy 07-22-2007 02:48 PM

Re: Blood Flow Restriction during Low-Intensity Resistance Exercise Increases S6K1 Phosphorylation and Muscle Protein Synthesis.
 
Ok. I don't do statics very often but when I did them I never really felt like they caused occulusion.

Streetman 07-24-2007 10:01 PM

Re: Blood Flow Restriction during Low-Intensity Resistance Exercise Increases S6K1 Phosphorylation and Muscle Protein Synthesis.
 
Sooo...how can we put this into real world practice? The way I read this article, as silly as this sounds, if I tie off my biceps like a introvenious drug user, and then do curls, I'm going to induce hytropophy to a greater extent. Is this correct?

I'm going look like a moron in the weight room. Oh well.

Fahsy 07-25-2007 12:25 AM

Re: Blood Flow Restriction during Low-Intensity Resistance Exercise Increases S6K1 Phosphorylation and Muscle Protein Synthesis.
 
Yeah, that's basically how it would be applied. And who cares what people think, you're at the gym to get big.

airborneninja 07-30-2007 10:40 PM

Re: Blood Flow Restriction during Low-Intensity Resistance Exercise Increases S6K1 Phosphorylation and Muscle Protein Synthesis.
 
And to fight the myth that the squat rack is for pushups.

MartinofSweden 08-12-2007 03:37 PM

Re: Blood Flow Restriction during Low-Intensity Resistance Exercise Increases S6K1 Phosphorylation and Muscle Protein Synthesis.
 
I tried this traing method a while back, and even though the rubber bands I used around my upper arms didnīt remotely cause a complete occlusion, the pain I experienced both during the sets and in between really made working out a challenge. Iīm not sure you can get a similar experience if you train isometrically, even though muscle contraction causes an occlusion, but by working dynamically without losing tension at the end and/or beginning of the motion youīll probably get close. The most challenging part about training with external occlusion would still be the time between sets. The pump you get is almost unbearable, because blood is forced into the body part thatīs being trained, but it canīt escape back, even after you finished a set. I hope I donīt scare anyone off from trying this, just want you to be prepared for pain. I personally havenīt abandoned this method yet though, even though Iīll need to convince myself pretty hard that itīs going to be benefitial before I pursue it again. Iīm still trying to figure out what to use instead of the thin rubber bands I used. I used like 12-15 small ones on each arm but it felt like the partial pressure to my skin was a bit to high - almost like it was going to break my skin. So I dont think I wanna do that again. If any of you guys has any ideas just let me know.

Venom 08-12-2007 04:06 PM

Re: Blood Flow Restriction during Low-Intensity Resistance Exercise Increases S6K1 Phosphorylation and Muscle Protein Synthesis.
 
[ QUOTE ]
Whats really interesting to me, is that a lot of studies on protein synthesis attribute the increase in protein synthesis to enhanced blood flow (and particularly extracellular amino acid delivery). And off course, bodybuilders have always been huge on training to the "pump."

[/ QUOTE ]

After doing this a few times, like martin stated, I noticed the pump is larger. It appears that blood just gets trapped their and can't escape. So its more like a continual pump, actually supporting the bodybuilding notion of inducing big pumps for growth.

Martin

Layne Norton said he wrapped two size "small" weight belts around his legs for thighs. I used an LP support wrap. I also used a rope from my robe. I can't imagine using rubber bands. That would kill the skin!


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