Alanyl-Glutamine or Alanine + Glutamine? Dipeptide or Free Form Aminos? What Offers Maximal Muscle Protection?

"Wouldn't have happened if she'd used alanyl-glutamine instead of regular that cheap alanine + glutamine combo!" - True or False? Recent study says: False!

If you combine your liver's favorite gluconeogenic amino acids, i.e. alanine and glutamine, into a single peptide the result is called alanyl-glutamine and marketed as the ueber-potent alternative to regular l-glutamine supplements. It goes without saying that a comparison like this is about as stupid as comparing french fries with mayo to regular french fries and saying that the former are worse because they contain more fat, or whatever. Even if we didn't care about the physiological significance of the effects of alanyl-glutamine, we would obviously have to compare the purported cryogenic effects of this "innovative" dipeptide to those of a simple combination of free form amino acids to deserve the bragging rights for having created an advanced form of glutamine.

Alanine + glutamine vs. alanyl-glutamine - fight!

By now you are probably asking yourselves why I am bothering you with things like this. Right? Well, the reason is that Éder Ricardo Petry and his colleagues from the University of Sao Paulo must recently have been pondering the same question. To answer it, they conducted an experiment that would allow them to verify if the oral supplementation with l-glutamine and l-alanine as dipeptide has more pronounced muscle protective effects than a simple mixture of l-glutamine and l-alanine (GLN+ALA, both in their free forms) in a group of Wistar rats that are subjected to intense aerobic training (treadmill).

I know what you are thinking now: "Not another rodent study...", but think about it: How many people are willing to pay $50 and more on supplements without any in vivo evidence of their efficacy let alone long-term safety? Against that background Petry's rodent is a major advancement - isn't it?

True or False: You can (ab-)use glutamine to replenish your glycogen stores!? True! It sounds strange, but according to a study from the late 20th century glutamine is a pretty effective glycogen replenisher, even in the absence of your bodies favorite nitrous glucose precursor alanine | learn more

Don't get me wrong, there are a few alanyl-glutamine studies in humans, but there is not a single one that would compare the dipeptide to a reasonable placebo in an exercise scenario. I mean, who tells me that the basketball players in the 2012 study by Hoffman et al. wouldn't have experience the same beneficial effects on basketball skill performance and visual reaction time if their rehydration solution had contained alanine and glutamine or even glutamine alone? Yes, I know... the increased absorption: Well, let's just look at a fair comparison, i.e. the study at hand, and see what happens when the dreams of supplement formulators and reality meet ;-)

Ok, back to the facts - the exercise & supplementation protocol

The male Wistar rats, the researchers used in their experiment were exercised 5x per week - at increasing intensities: Starting with 30 and 45 min of treadmill running (incline 3°) at 20 and 22.5 m/min in the first three weeks, the speed and duration of their treadmill runs increased to 60 min at a speed of 25 m/min in week four and remained like that for the rest of the 8-week study period.

The supplements were administered via oral gavage in the course of the last 3 weeks, only. The daily doses for the animals in the dipeptide (DIP) and free form amino acid groups (GLN+ALA) were...

• 1.5g/kg alanyl-glutamine in the DIP group,
• 0.67g/kg l-alanine + 1.0g/kg l-glutamine in the GLN+ALA group, and
• plain water in the control group

The amount of of alanyl-glutamine the scientists used was calculated in such a way that the total amount of l-glutamine was the same as that of l-glutamine administered in its free form.

Changes? YES! Dipeptide benefits? Not really...

The gavage was provided 1 h after the end of each session of exercise, after which the animals had with free access to water and chow. To make sure that the results of the examinations on the last day of exercise would not reflect the acute effects of a single dose of the supplements, the animals were killed 10 h after the last exercise session.

Figure 1: Plasma glutamine, glutamate, ammonium, malondialdehyde, myoglobin, and creatine kinase activity in Wistar rats supplemented with alanyl-glutamine (DIP) or regular glutamine + alanine; data expressed rel. to control (Petry. 2013)

The virtually identical increases in l-glutamine and l-glutamate, you see in Figure 1 should thus represent the baseline and not the 'immediately post supplementation level' of these amino acids. For the exercise-induced accumulation of ammonium, malondialdehyde (MDA; indicates lower lipid oxidation), myoglobin and creatine kinase (both indicate lower muscle damage) the timing is not that important, anyway. What is important, however, is the fact that there were no physiologically relevant advantages for the "super glutamine".

DHEA & estrogen are alternative muscle protectors. Despite the fact that estrogen has repeatedly been shown to have muscle protective-effects, I would not suggest you steel your granny's HRT medication. DHEA on the other hand, may be something to consider - specifically if you are about to overreach, like the male subjects in a 2012 study by Liao et al. (learn more)

If we take a closer look at the p-values and the statistical significance of these changes, it turns out that, the minor increase in glutamate aside, all of the difference to the placebo group were statistically significant. The DIP vs. GLN+ALA differences, on the other hand, were marginal and reached statistical significance only in the case of the marker of myoglobin. Where the dipeptide has a physiologically probably irrelevant edge of 9% over the GLN + ALA combination.

Figure 2: Glutathione (GSH) and glutathione disulfide (GSSG = used glutathione) levels in soleus and gastrocnemius skeletal muscles of the rodents; data expressed relaitve to control (Petry. 2013)

For the muscular GSH levels, it does not look much different. In this case, there is however not even a statistical difference between alanyl-glutamine and the simple l-alanine + l-glutamine mix - neither for the universal anti-oxidant glutathione (GSH), nor for its "used form" glutathione disulfide (GSSG).

Does that mean that alanyl-glutamine is another supplemental rip-off? I would say that it's too early to use such harsh words. There was after all one statistically, and maybe even physiologically relevant difference between the two groups I didn't mention, yet: The dipeptide group presented with a different heat-shock protein response: They had higher HSP-70 and lower HSF-1 levels in the soleus and lower HSP-70 and lower HSF-1 levels in the gastrocnemius.

"Will training your biceps, heal your heart & protect your brain!?" - a study on the effects of exercise induced HSP increases suggests so | more

In view of the fact that the subsequent "deficit in HSP70 expression" is supposed to "impair recovery from these injuries" Petry et al. are probably right to point out that

"one cannot discard the possibility that part of the beneficial effects of high-intensity exercise training may be due to the enhancement of HSP70 expression which is exacerbated by glutamine supplementation."

In view of the fact that the total amount of proteins from the HSP70 and HSF1 family was increased in both groups, and the differences appear random, it is impossible to tell, whether the slight differences in HSP expression actually matter and whether this is an advantage for alanyl-glutamine or rather for the cheap free form amino acids.

Before future studies provide additional data based on which we can decide whether these differences are relevant and why they differ between slow- (soleus) and fast-twitch (gastrocnemius) skeletal muscle fibers, I'd say that the study at hand would suggest that alanine and glutamine have muscle protective effects irrespective of whether they are bound or not, when you ingest them.

References:

• Cruzat VF, Rogero MM, Tirapegui J. Effects of supplementation with free glutamine and the dipeptide alanyl-glutamine on parameters of muscle damage and inflammation in rats submitted to prolonged exercise. Cell Biochem Funct. 2010 Jan;28(1):24-30. 
• Cruzat VF, Tirapegui J. Effects of oral supplementation with glutamine and alanyl-glutamine on glutamine, glutamate, and glutathione status in trained rats and subjected to long-duration exercise. Nutrition. 2009 Apr;25(4):428-35.
• Hoffman JR, Williams DR, Emerson NS, Hoffman MW, Wells AJ, McVeigh DM, McCormack WP, Mangine GT, Gonzalez AM, Fragala MS. L-alanyl-L-glutamine ingestion maintains performance during a competitive basketball game. J Int Soc Sports Nutr. 2012 Mar 7;9(1):4.
• Petry ER, Cruzat VF, Heck TG, et al. Alanyl-glutamine and glutamine plus alanine supplements improve skeletal redox status in trained rats: Involvement of heat shock protein pathways. Life Sciences. 20 November 2013 [ahead of print]
• Rogero MM, Tirapegui J, Pedrosa RG, Castro IA, Pires IS. Effect of alanyl-glutamine supplementation on plasma and tissue glutamine concentrations in rats submitted to exhaustive exercise. Nutrition. 2006 May;22(5):564-71.

Shedding Some Light on the Leaky Gut <> Exercise Connection. Plus: 20+ Things You Should or Shouldn't Do to Protect and Restore the Integrity of Your Intestinal Wall

Have you ever felt nauseated after a workout? Or does your protein supplement gives you diarrhea only if you take it right after a workout? Both can be related to the toll  exercise can take on the integrity of your intestinal tract.

To be honest, I was quite surprised that I did not get a hell lot of hatemail in response to the the 'MSG heals the gut study' I posted last Sunday... Be that as it may, I feel sort of awkward to have opened Pandora's box without proving you with some betters tools than mono-sodium glutamate (MSG) to seal the box, or rather your leaky gut, again. Therefore I decided to post this mini-feature on a particular issue all of us will be dealing with: An exercise induced increase in gut permeability. As you are going to see, there are a lot of similarities to the 'classic' leaky gut, which is often implicated in the etiology of chronic inflammatory bowel diseases. In order to understand these similarities, but also the few, yet important differences, we will have to lay some theoretical groundwork.

"What exactly is a leaky gut?"

The easiest way to answer this question would be to say: "That's what everybody and his mama is talking about these days". This definition as concise (and precise) as it may be, is yet about as productive as the talk that's at its heart. So, instead of relying on hearsay, let's rather briefly recap how intestinal wall actually works.

Since the intestines are meant to let nutrients and fluid pass, a certain degree of leakiness is absolutely natural. Problems arise only, when the self-regulatory system is broken and/or the permeability exceeds a normal / healthy threshold (img. by Mariana Ruiz).

The mucosal layer of the intestinal tract is made up of epithelial cells, so-called enterocytes which are connected to one another by specialized proteins. These proteins form the tight junctions (TJ) - a term, you will probably have encountered numerous times before. The main constituents of this kit in between the enterocytes are proteins such as occludin, zona-occludens and claudins. Together, the array of enterocytes and the tight junction form the the intestinal barrier, which allows the absorption of nutrients and water, while preventing the translocation of harmful substances from the gut into the bloodstream.

The integrity of this barrier is influenced by the phosphorylation state of the proteins within the tight junctions.The exact interactions are compilcated and can be looked up elsewhere (Banan. 2005). What's important for you to realize is that during prolonged exercise which is necessarily accompanied by an increase in core temperature, cardiovascular and thermoregulatory responses compromise intestinal blood flow.

With the core temperature usually being lower than the temperature in your intestines, the temperature of your gut can easily approach 41°C during a workout.That's more than your epithelial cells can handle and can lead to structural damage of the 'patches' in the tight junctions + epithelial cell layer (Lambert. 1985).

HIIT veterans or weight lifters are not off the hook

Now, the last paragraph may have sounded as if only long endurance workouts like 10k-runs or marathons could entail damage to the intestinal cells. That's however not the case, since the redirection of the blood away from the splanchnic arteries and to the working muscle that's even more pronounced in high(er) intensity exercise, will initiate an ischaemia reperfusion cycle which can entail oxidative damage not during, but interestingly after the the workout, when the blood rushes back into the intestines (Wijck. 2011).

Take home message: There are two distinct pathways that contribute to the leaky gut during and after a workout (a) heat and (b) ischaemic/reperfusion stress. Both influcne the phosphorylation state of the proteins in the tight junctions and will thus increase the permeability of the gut lining.

It stands to reason that the combination of high intensity and long durations, as you will find it in an ultra-marathon runner, for example, is particularly detrimental to the integrity of the intestinal wall, so that it is not exactly surprising that (ultra-)endurance athletes have the highest prevalence (60-90%) of gastrointestinal distress that which manifests in the form of diarrhoea, nausea, stomach problems, bloating and intestinal cramps (Worobetz.1985; Peters.1999; Jeukendrup.2000)

There is more than one thing you can to to protect, heal and restore your gut integrity

The fact that a "leaky gut" is like an open door not just for exogenous toxins or live bacteria, but also for their 'endotoxic poop' is probably no news for you. In fact, it is also the reason why you want to either prevent the pathological increases in gut permeability, in the first place, and/or (re-)seal the gut as soon as possible after your workouts. In this regards, there are three fundamental and easily implementable strategies that should always be employed before you even think about using specific supplements:

• 

  Figure 1: HSP 70 offers protection against endotoxins (LPS) in vivo (top) and in vitro (bottom; Dokladny. 2010)

  Despite the possible ischaemic / reperfusion stress short high intensity exercise bouts like sprinting are generally less taxing on the integrity of the tight junctions than longer duration medium intensity aerobic workouts. Avoiding these particularly gut-stressing workouts and/or taking special precautions before and after marathons and other endurance events would thus be strategy #1 to keep the epithelial cell layer intact and pathogens and toxins from entering the circulation.
• The natural intracellular expression of heat shock proteins (HSPs) can protect the tight gut junctions during and/or help their restoration after a workout. Just like all our endogenous protection systems the production of HSPs can be trained. Giving your body the time it needs to accommodate by making small, but consistent steps towards longer and/or more intense workouts would therefore be strategy #2.
• That leaves us with strategy #3, of which I hope all of you will be using anyway - even if you have not been aware of its gut protective effect, yet: The provision of adequate fluid supply before, during and after a workout (Lambert. 2008).

As the workout durations become longer and longer and/or the respective intensities higher and higher, solely relying on your bodies self-healing capacity and adequate hydration may seize to work, though. Despite the fact that our bodies accommodate to the ever increasing demand for intracellular protection against heat stress by upregulating the HSP expression (athletes have higher HSP expression to a standardized endurance training protocol than normal individiuals; cf. Fehrenbach. 2000), there is - just as with about every adaptive response - a certain threshold, when hormesis, i.e. the beneficial adaptation to a manageable amount of stress, is no longer an option.

From "A" as in arginine to "Z" as in zinc - a list of things to keep the gut lining intact

While there has been quite a lot of research as of late into which dietary supplements and even regular foodstuff would be able to modulate the heat shock proteins in order to prefer the desired downstream benefits on gut integrity, the number of compounds of which it is reasonable to assume that they can actually make a difference is still very small:

• Colostrum supplementation to cell cultures has been shown to increase the expression of HSP-70 in human epithelial cells; studies with human subjects are rare and ambiguous:  While Marchbank et al., have been able to show that bovine colostrum truncates the increase in gut permeability caused by heavy exercise in athletes (Marchbank. 2011), Buckley et al. actually observed detrimental effects of 8 weeks of bovine colostrum supplementation on the exercise induced gut permeability in runners (Buckley. 2009).The explanation for these discrepencies is not clear, but may be related to the longer duration / different intensity of the exercise protocols, or differences in the immunoglobolin, peptide or amino acid composition of the supplements.
• Zinc in general and specifically polaprezinc, a zinc based anti-ulcer drug, which has primarily been used in Japan as a means to seal leaky Japanese guts, show some promises, as in the treatment and prevention of increased intestinal permeabilty (Zhang. 2009). It is thought that zinc is critical for tight junction assembly and has been shown to be critical in the protection of the gut lining from the chronic toxic assault of alcohol (Zhong. 2010). That being said, you should keep in mind that alcohol will deplete your bodies zinc stores, so that it cannot be said, if someone with an adequate zinc intake would benefit to the same degree as a zinc deficient alcoholic. Moreover, as "natural" as they may be, even essential minerals like zinc don't come without potential side effects (cf. "After 120 Days Rodents on Diets Containing 2xRDA of Zinc Develop Metabolic Syndrome", read more).
• Glutamine has been used as treatment for patients suffering from irritable bowel syndrome and Crohn’s disease and has been shown to actively increase the expression of HSP70 in critically ill patients (Jonas. 1999; Ziegler. 2005).  
• Berberine could be an ideal addition to glutamine (thx to Maxim Okhrimenko for pointing that out in the comments); berberine does not only modulate the TNF-alpha response in the intestines and increases AKT, but has also been shown to maintain / rescue intestinal glutamine transport and glutaminase activity (Gu. 2009; Amasheh. 2010; Li. 2010; Niu. 2011)
• Probiotics are still an 'under-researched' newcomer and though there is some preliminary evidence pointing to the efficacy of probiotic therapy as a means of improving gut function and enhancing the integrity of the intestinal tight junctions, the ideal supplement regimen, as well as its long-term effects will still have to be elucidated in human studies. Studies by Ewaschuk et al. have yet already shown that the impact factors released from Bifidobacteria infantis can offer a certain degree of protection against experimentally induced colitis in rodents (Ewaschuk. 2008). As far as exercise specific studies are concerned, a recently published paper by Lamprecht et al. is probably the first peer reviewed human study to report allegedly "borderline significant" beneficial effects on gut permeability (measured only indirectly by quantifiying the zonolin conent of the feces) and TNFalpha expression in response to a multi-species probiotics (1010 CFU/day, Ecologic®Performance orOMNi-BiOTiC®POWER) in 23 trained men (Lamprecht. 2012; the study was partially funded with a grant from Winclov, the manufacturer of the respective supplements).
• Butyrate, yet not all short chain fatty acids, have recently been found to decrease gut permeability (Ferreira. 2012). Both data from human studies, as well as exercise specific data is yet still absent.
• Hydroxypropyl methylcellulose (HPMC), which is a non-fermentable fiber, has been shown to protect rodent guts from a high fat diet induced increase in gut permeability (Kim. 2012), as in the case of butyrate its efficacy (and when you think about athletes, tolerability) will yet still have to be confirmed in human trials.
• L-Arginine (and AAKG) as a source of nitric oxide, which is necessary to protect the gut barrier from invaders could have a protective effect, as well (Quirino. 2012); and though this effect is not exercise specific, we know that arginine requirements increase in states of chronic stress, it would therefore be logical that supplementation with l-arginine, or even better AAKG, which comes with a precursor to glutamine will have beneficial effects on the tightness of the guts of intensely training athletes, as well (suggested read: BCAAs, glutamine and ammonia detox) .
• Oats, maybe due to their beta glucan content and their ability to increase the production of short-chain fatty acids in the large intestine, oats offer protection against alcohol induced increases in tight junction permeability (Tang. 2009); exercise specific studies have yet to be conducted, though.Personally I would yet not be surprised if this would turn out to be very effective (note: as long as they are not cross-contaminated, oats are 100% gluten-free)
• Goats milk (powder) has been shown to be equally effective as colostrum in reducing heat and thus most likely exercise induced gut permeability (Prosser. 2004)
• Lactoferrin, a multifunctional protein of the transferrin family that is present in milk may have protective effects against LPS-mediated intestinal mucosal damage and impairments of the barrier function in intestinal epithelial cells (Hirotani. 2008)
• Vitamin A in adequate amounts is necessary to maintain gut integrity; it is likely that this is all the more true if gut integrity and immune function are additionally challenged by strenuous exercise (Quadro. 2000)

I guess, I could find even more supplements (and foods) that may help you protect or restore your gut lining, but let's be honest: As important and beneficial eating and supplementing the right things may be, all your efforts would be foiled if you eat foods and supplements that will have the opposite effect on your gut lining. So here is the complementary and likewise non-exhaustive list of stuff you'd better avoid (at least in high doses) if you want to keep your tight junctions intact and your gut from becoming leaky:

Figure 2: Gliadin peptides induce the release of zonulin which in turn interacts with the tight junctions and increases the diffusion of small molecules (∼350 Da) across the cell membrane. Whether the tight junctions open up wide enough to allow for free diffusion of whole gliadin peptides, whose molecular weight is at least 2000 Da, remains to be determined, though (Heyman. 2011)

• Alcohol will wreak havoc on the permeability of your intestines; probably in consequence of its depleting effect on ileal zinc concentration (Zhong. 2010).
• Gliadin (in wheat/gluten) does actively promote the release of zonolin and the widening of the tight junctions (see figure 2); whether you will notice that or not, depends on the occurrence and extent of an immune response as it is characteristic for Celiac patients. I guess, it's actually not necessary to say that all sorts of other allergens, respectively the ensuing inflammatory response to being exposed to them will have detrimental effects on the integrity of your gut, as well, right?
• ALA, EPA and DHA the dietary omega-3 fatty which may help sooth tight junction permeability in states of chronic inflammation will actually increase it, when the baseline inflammation is already low or they are consumed in excess (Usami. 2001; Roig-Pérez. 2010)
• Copper and iron increase tight junction permeability of caco-2 cells via distinct mechanisms (Ferruzza. 2002)
• Capsaicin, piperine and other hot spices do not only cause a burning sensation in your mouth, it literally burns your intestinal cell lining, as well (Johri. 1992; Tsakura.2007)
• Quercitin by blocking the increase in HSP-70 will increase the suceptibility of your gut to exercise induced increases in permeablity (Kuennen. 2011)
• NSAIDs like aspirin and ibuprofen increase the permeability of the gut ad amplify the potentially detrimental effects of exercise (Lambert. 2007)

Obviously, only few of the last mentioned offenders are exercise specific, but if you start working out with already compromised gut integrity, you can hardly complain if a couple of grams of glutamine, or whatever else you may have picked from the previous list, don't effectively protect your intestinal wall from damage. What's even more important though is that you understand the Janus-faced nature of anti-oxidants and anti-inflammatory compounds. As beneficial as they may be in situations of chronic or acute pathologic inflammation, NSAIDs, quercitin and even your beloved omega-3 can eventually extinguish the 'controlled fire' your body needs to keep all immune and metabolic functions simmering along nicely (suggest reads: "Are you stressed enough for a longer life?" and "Inflammation is a True Fat Burner").

References:

• Amasheh M, Fromm A, Krug SM, Amasheh S, Andres S, Zeitz M, Fromm M, Schulzke JD. TNFalpha-induced and berberine-antagonized tight junction barrier impairment via tyrosine kinase, Akt and NFkappaB signaling. J Cell Sci. 2010 Dec 1;123(Pt 23):4145-55.
• Banan A,Zhang LJ, Shaikh M,et al. theta Isoform of protein kinase C alters barrier function in intestinal epithelium through modulation of distinct claudin isotypes: a novel mechanism for regulation of permeability. J Pharmacol Exp Ther. 2005; 313:962–82.
• Buckley JD, Butler RN, Southcott E, Brinkworth GD. Bovine colostrum supplementation during running training increases intestinal permeability. Nutrients. 2009 Feb;1(2):224-34.
• Dokladny K, Lobb R, Wharton W, Ma TY, Moseley PL. LPS-induced cytokine levels are repressed by elevated expression of HSP70 in rats: possible role of NF-kappaB. Cell Stress Chaperones. 2010 Mar;15(2):153-63. Epub 2009 Jun 24. 
• Ewaschuk JB, Diaz H, Meddings L, Diederichs B, Dmytrash A, Backer J, Looijer-van Langen M, Madsen KL. Secreted bioactive factors from Bifidobacterium infantis enhance epithelial cell barrier function. Am J Physiol Gastrointest Liver Physiol. 2008 Nov;295(5):G1025-34. 
• Ferruzza S, Scacchi M, Scarino ML, Sambuy Y. Iron and copper alter tight junction permeability in human intestinal Caco-2 cells by distinct mechanisms. Toxicol In Vitro. 2002 Aug;16(4):399-404. 
• Gu L, Li N, Li Q, Zhang Q, Wang C, Zhu W, Li J. The effect of berberine in vitro on tight junctions in human Caco-2 intestinal epithelial cells. Fitoterapia. 2009 Jun;80(4):241-8.
• Heyman M, Abed J, Lebreton C, Cerf-Bensussan N. Intestinal permeability in coeliac disease: insight into mechanisms and relevance to pathogenesis. Gut. 2012 Sep;61(9):1355-64.
• Hirotani Y, Ikeda K, Kato R, Myotoku M, Umeda T, Ijiri Y, Tanaka K. Protective effects of lactoferrin against intestinal mucosal damage induced by lipopolysaccharide in human intestinal Caco-2 cells. Yakugaku Zasshi. 2008 Sep;128(9):1363-8.
• Jeukendrup AE,Vet-Joop K, Sturk A,et al. Relationship between gastrointestinal complaints and endotoxaemia, cytokine release and the acute-phase reaction during and after a long-distance triathlon in highly trained men.Clin Sci (Lond). 2000;98:47–55. 
• Jonas CR, Ziegler TR. Potential role of glutamine administration in inflammatory bowel disease. Nestle Nutr Workshop Ser Clin Perform Programme. 1999;2:217-30.
• Johri RK, Thusu N, Khajuria A, Zutshi U. Piperine-mediated changes in the permeability of rat intestinal epithelial cells. The status of gamma-glutamyl transpeptidase activity, uptake of amino acids and lipid peroxidation. Biochem Pharmacol. 1992 Apr 1;43(7):1401-7.
• Kim H, Bartley GE, Young SA, Davis PA, Yokoyama W. HPMC supplementation reduces abdominal fat content, intestinal permeability, inflammation, and insulin resistance in diet-induced obese mice. Mol Nutr Food Res. 2012 Sep;56(9):1464-76. 
• Kuennen M, Gillum T, Dokladny K, Bedrick E, Schneider S, Moseley P. Thermotolerance and heat acclimation may share a common mechanism in humans. Am J Physiol Regul Integr Comp Physiol. 2011 Aug;301(2):R524-33.
• Lambert GP, Gisolfi CV, Berg DJ, Moseley PL, Oberley LW, Kregel KC. Selected contribution: Hyperthermia-induced intestinal permeability and the role of oxidative and nitrosative stress. J Appl Physiol. 2002 Apr;92(4):1750-61; discussion 1749. PubMed PMID: 11896046.
• Lambert GP, Boylan M, Laventure JP, Bull A, Lanspa S. Effect of aspirin and ibuprofen on GI permeability during exercise. Int J Sports Med. 2007 Sep;28(9):722-6.
• Lambert GP, Lang J, Bull A, Pfeifer PC, Eckerson J, Moore G, Lanspa S, O'Brien J. Fluid restriction during running increases GI permeability. Int J Sports Med. 2008 Mar;29(3):194-8.
• Lamprecht M, Bogner S, Schippinger G, Steinbauer K, Fankhauser F, Hallstroem S, Schuetz B, Greilberger JF. Probiotic supplementation affects markers of intestinal barrier, oxidation, and inflammation in trained men; a randomized, double-blinded, placebo-controlled trial. J Int Soc Sports Nutr. 2012 Sep 20;9(1):45. 
• Li N, Gu L, Qu L, Gong J, Li Q, Zhu W, Li J. Berberine attenuates pro-inflammatory cytokine-induced tight junction disruption in an in vitro model of intestinal epithelial cells. Eur J Pharm Sci. 2010 Apr 16;40(1):1-8.
• Marchbank T, Davison G, Oakes JR, Ghatei MA, Patterson M, Moyer MP, Playford RJ. The nutriceutical bovine colostrum truncates the increase in gut permeability caused by heavy exercise in athletes. Am J Physiol Gastrointest Liver Physiol. 2011 Mar;300(3):G477-84.
• Musch MW, Sugi K, Straus D, Chang EB. Heat-shock protein 72 protects against oxidant-induced injury of barrier function of human colonic epithelial Caco2/bbe cells. Gastroenterology. 1999 Jul;117(1):115-22. 
• Niu L, Qiao W, Hu Z, Li N, Huang Q, Gong J, Li Q, Zhu W, Li J. Berberine attenuates lipopolysaccharide-induced impairments of intestinal glutamine transport and glutaminase activity in rat. Fitoterapia. 2011 Apr;82(3):323-30.
• Peters HP, Bos M, Seebregts L,et al. Gastrointestinal symptoms in long-distance runners, cyclists, and triathletes: prevalence, medication, and etiology. Am J Gastroenterol. 1999; 94:1570–81. 
• Prosser C, Stelwagen K, Cummins R, Guerin P, Gill N, Milne C. Reduction in heat-induced gastrointestinal hyperpermeability in rats by bovine colostrum and goat milk powders. J Appl Physiol. 2004 Feb;96(2):650-4.
• Quadro L, Gamble MV, Vogel S, Lima AA, Piantedosi R, Moore SR, Colantuoni V, Gottesman ME, Guerrant RL, Blaner WS. Retinol and retinol-binding protein: gut integrity and circulating immunoglobulins. J Infect Dis. 2000 Sep;182 Suppl 1:S97-S102.
• Roig-Pérez S, Cortadellas N, Moretó M, Ferrer R. Intracellular mechanisms involved in docosahexaenoic acid-induced increases in tight junction permeability in Caco-2 cell monolayers. J Nutr. 2010 Sep;140(9):1557-63.
• Ruiz M. Wikipedia contributors, 'Tight junction', Wikipedia, The Free Encyclopedia, 10 November 2012, 07:58 UTC, <http://en.wikipedia.org/w/index.php?title=Tight_junction&oldid=522300074> accessed 25 November 2012
• Tang Y, Forsyth CB, Banan A, Fields JZ, Keshavarzian A. Oats supplementation prevents alcohol-induced gut leakiness in rats by preventing alcohol-induced oxidative tissue damage. J Pharmacol Exp Ther. 2009 Jun;329(3):952-8.
• Tsukura Y, Mori M, Hirotani Y, Ikeda K, Amano F, Kato R, Ijiri Y, Tanaka K. Effects of capsaicin on cellular damage and monolayer permeability in human intestinal Caco-2 cells. Biol Pharm Bull. 2007 Oct;30(10):1982-6.
• Usami M, Muraki K, Iwamoto M, Ohata A, Matsushita E, Miki A. Effect of eicosapentaenoic acid (EPA) on tight junction permeability in intestinal monolayer cells. Clin Nutr. 2001 Aug;20(4):351-9.
• van Wijck K, Lenaerts K, van Loon LJ,et al. Exercise-induced splanchnic hypoperfusion results in gut dysfunction in healthy men.PloS One. 2011; 6.
• Worobetz LJ,Gerrard DF. Gastrointestinal symptoms during exercise in Enduro athletes: prevalence and speculations on the aetiology.N Z Med J 1985; 98:644–6.
• Zhang B, Guo Y. Supplemental zinc reduced intestinal permeability by enhancing occludin and zonula occludens protein-1 (ZO-1) expression in weaning piglets. Br J Nutr. 2009 Sep;102(5):687-93.
• Zhong W, McClain CJ, Cave M, Kang YJ, Zhou Z. The role of zinc deficiency in alcohol-induced intestinal barrier dysfunction. Am J Physiol Gastrointest Liver Physiol. 2010 May;298(5):G625-33. 
• Ziegler TR, Ogden LG, Singleton KD, Luo M, Fernandez-Estivariz C, Griffith DP, Galloway JR, Wischmeyer PE. Parenteral glutamine increases serum heat shock protein 70 in critically ill patients. Intensive Care Med. 2005 Aug;31(8):1079-86

On Short Notice: Red Onions For Glutathion & Jiagulan For Muscle Glycogen, Low Iron & Obesity, Sodium Caprate, Useless Probiotics & Leaky Gut, Perivascular Fat & Heat Shock Proteins for Your Heart & Magnesium vs. Migraine

Image 1: You may already have read it on the SuppVersity Facebook Wall; "Sacrificing sleep in order to study won't improve your college grades..." it could however easily whack your circadian rhythm and give you headaches. If those turn into a migraine, you may be happy to have read about beneficial effects of magnesium on the incidence of these crippling and painful attacks (see last item in this installment of "On Short Notice" ).

In order to avoid having another weekend of "On Short Notice" posts, I decided to post the first collection today, already. The topics are, as usually, only loosely related and I hope that each and everyone of you will find something he or she considers interesting. We'll start out by having a brief look at the amazing antioxidant effects of red onions, and then delve deeper into the connection between obesity and low ferritin levels and a brief reminder that sometimes good things can become bad, if they are not handled properly, next on the list are the tight gut junction opening effects of sodium caprate which may be a good thing if your goal is to increase the bioavailability of berberine, but a very bad thing, if other molecules take the opportunity and pass through the open doors, as we are then going to see Dr. Shirota's probiotics are probably not going to help you avoid this problem and they are certainly not helping patients with metabolic syndrome: The latter is probably also true for PPAR-gamma antagonists, which may help prevent visceral fat accumulation, but could at the same time precipitate to heart disease by decreasing the surprisingly heart-healthy perivascular fat.

Although more of an ergogenic, Gynostemma penthaphylum (aka Jiagulan) is probably a more promising strategy to get in better shape. If it allows you to train harder, it will also allow you to make better use of potential systemic health effects of exercised induced heat shock protein expression... and just in case all that was so much information that you are having a headache once you have arrived at the end of this blogpost, a 500mg dose of magnesium could help you reduce the incidence of migraine attacks by more than 60% whether additional 500mg of carnitine make this treatment even more effective does yet remain to be elucidated!

• Do your liver and body antioxidant system a favor and add a couple of red onions to your diet! That's the straight forward take home message from a recently conducted study by a group of Korean scientists (Lee. 2012). The researchers had investigated  the effect of red onion on the total activity of antioxidant enzymes in 18-week-old Sprague-Dawley rats. To this ends the rodent had been kept on a diet enriched with red onion peel, flesh or both (all pulverized and mixed into the standard chow for a total content of 5g per 100g) for for weeks.

  

  Figure 1: The red onions outperformed easily outperformed their uncolored white brethren and cousin, white onions and garlic, in the in vitro dish and had profound antioxidant boosting effects in the in vivo study (Lee. 2012).

  The results, (a) a significant increase in plasma SOD activity in the red onion peel and red onion (peel + flesh) groups, (b) a significantly higher GPX (enzyme that recycles glutathione) activity in the in the red onion flesh group and (c) a general tendency towards higher catalase and ORAC activity in the livers and profoundly reduced liver malondialdehyde (=marker of lipid peroxidation) levels in the red onion groups provide an in vivo (allegedly only "in rodent vivo" ;-) confirmation of the in vitro data in figure 1 which is - as usual - to be treated with caution before respective experiments in complex, real organisms confirm that they are more than artifacts of the respective essay.
• Low iron (ferritin) associated with obesity in adolescents, but simple eating more iron probably won't solve either the iron deficiency, nor the (central) obesity. That's at least what the results of a recent investigation in normal and fat Greek kids would suggest, after all the fat kids did already consume more iron in their diets than their lean age-mates (Moschonis. 2012).
  What makes this study worth mentioning is the (as usual hasty) conclusion that iron must be a bad guy, when just its mismanagement (probably as a result of adiposity induced liver problems, or, as a handful of older and recent studies would suggest vitamin A deficiency; e.g. Arruda. 2009; Citelli. 2012; Yohsikawa. 2012) is a problem - so don't get fooled, donating blood every other week won't lean healthy people out, it will just drain them out.

• 

  Figure 2: Sodium caprate won't "open" the tight gut junctions for berberine, only, but also for all sorts of other, mostly unwanted junk - self-induced temporary leaky gut so to say!

  Sodium caprate opens tight junctions of the gut and let's berberine in. The consequence is an amplification of the hypoglycemic effects of berberine (Lv. 2012), but at the same time it is likely to amplify the effects of whatever you else put into your mouth or the critters that live in your stomach are pooping out - I guess it should be obvious that I am referring to the LPS assault from your gut microbiome, here and that the potential increase in lipopolysaccharide could well outweigh (in a negative sense) the benefits you would see from an increased bioavailability (~1.5-2.3 fold; cf. Lv. 2010) of berberine.
  
  Against that background I am really not sure how sensible the use of sodium caprate or other "tight junction openers" of natural or pharamacological origin really is. But hey, that's just me - maybe you are less cautious...  if there are not yet any products like that on the market, it probably won't be long until the first "enhanced" berberine appear in the line-ups of the large "health supplement" vendors on the Internet.

• 

  Image 2: Patented lactobacillus strains are all the rave, and probably big business... that does yet not mean that they work - regardless of whether they carry the name of famous Drs or not ;-)

  Probiotic supplements don't cure everything - although many ads may give just this impression. In a recently published study, Swiss researchers were not able to show any beneficial effects of the patented L. casei Shirota strain on the increased gut permeability of 28 patients with metabolic syndrome (Leber. 2012). In the course of the three months study period, it rather exasperated the already elevated C-reactive protein levels, due to liposaccharide leakage through the leaky gut into the system and I bet the only reason that the conclusion states that the dosage may have been too low instead of "this is initial evidence that the use of L. casei Shirota is not useful if  not counter-indicated in to treat gut permeability in patients with MetS", was the financial support by Yakult Europe the patent holder of L. casei Shirota ;-)
• PPAR-gamma ablation leads to loss of perivascular adipose tissue (PVAT). What may at first sound great could in fact be deadly. The recently published results of Chang et al. show quite clearly that non-tissue-specific blockade of the "fat builder" PPAR-gamma (cf. "Tangeritin, Natural Metformin from the Rind of Mandarin Oranges Hits the OFF-Switch on Diet Induced Obesity") is a dangerous undertaking. While keeping the differentiation and growth of body fat at bay, especially in the abdominal region, would be a good thing, the high rate of atherosclerosis among the mice from the laboratories of the University of Michigan confirms that "not all body fat is created evil" (Chang. 2012).

  

  Figure 3: Fitzgibbons et al. were already able to show that the UCP-1 expression, which is a marker of metabolic activity, in PVAT is equally high as in the meanwhile infamous brown adipose tissue. In short - PVAT just like BAT will not just store superfluous lipids, it will also burn them and prevent them from accumulating in the vasculature (Fitzgibbons. 2011)

  As it turned out, PVAT, rather than being proinflammatory and hazardous, actually has a protective function on the vasculature it is sourrounding. In fact, the results Chang et al. are presenting in the latest issue of Circulation suggest the assumption that PVAT is anti-inflammatory and functionally similar to the metabolically active brown adipose tissue that has gotten quite some attention by experts ad laymen as of lat. When it's suddenly missing, the lipids inside the vascular can no longer be cleared into the perivascular adipose tissue where they would be oxidized and disposed of. In addition, the ensuing pro-atherogenic coupled with the absence of PVAT-derived prostacyclin, a prostanoid that's metabolized from endogenous arachidonic acid through the cyclooxygenase (COX) pathway and acts as a potent vasodilator (cf. Ruan. 2010) could thus easily set you up to die before your time - regardless of how lean you may have become...
  And though it is very unlikely that this is going to happen from the use of one of the freely available herbs with anti-PPAR-gamma effects (e.g. tashinones from Salvia miltiorrhiza, or the previously cited tangeritin), it certainly is a good reminder of how fatal our constant black-and-white thinking can be, when it is injudiciously applied to such complex matters as our own body.

• 

  Image 4 (dracoherbs.com): Gynostemma penthaphylum is also known as Jiaogulan, is often mentioned in the same breath with ginseng in TCM

  Gynostemma penthaphylum boosts endurance by ROS scavenging and multiplying skeletal muscle glycogen stores. Not yet another potent anti-oxidant was what I first thought,when I hit upon the soon-to-be published study from Shaanxi Normal University in Xi'an, China, but after taking a closer look it turned out that the way this century old adaptogen that goes by the name jiaogulanin TCM and is an herbaceous vine of the family Cucurbitaceae (cucumber or gourd family) indigenous to the southern reaches of China, northern Vietnam, southern Korea, and Japan, could actually make quite an exciting supplement (Chi. 2012). After all its high ROS(radical oxygen specimen) scavenging abilities are only part of what allowed the rodents in the study by Chi, Tang, Zhang & Zhang that had been treaded with isolated polysaccharides from this plant to go significantly longer during a standardized exercise performance test.
  The more intruiging part of the performance boost, however came from the direct pro-gluconeogenic and glyocogen storage promoting effects of the alpha variety of the three Gynostemma penhaphylum polyssacharides the scientists had extracted. If similar effects would be seen in humans, GP would certainly make a valuable addition to the regimen of anyone who does not just perform 1-rep maxes day in and day out - and let's face it: In view of the fact that the glycogen can't be synthesized from nothing, it could also help to burn body fat, by it's repartitioning effects.

• 

  Figure 4: It would certainly be an unwarranted overgeneralization to ascribe all beneficial effects of exercise to the systemic expression of heat shock proteins. But still, there is increasing evidence that their controlled expression does at least contribute to the numerous beneficial effects exercise has on our brains, hearts and other organs; interestingly these effects are likewise mediated by the breakdown and the protection and "recycling" of organ tissue.

  Will training your biceps, heal your heart and protect your brain!? You probably know that the scientists at the McMaster University have put the myth of the pro-anabolic effects of systemically circulating hormones that are released response to isolated muscle training (eg. "train your legs to increase your testosterone and see your arms grow") at rest, years ago. Now, a study that's soon going to be published in theh Journal of Experimental Biology suggests that testosterone, growth hormone and co. may not be the only molecules we should be looking for, when we talk about possible non-localized effects of exercise (Jammes. 2012). Another class of proteins that has gotten quite some attention esp. in the context of the profound effects of occlusion training, the so-called heat-shock proteins, which are released in response not just to heat, but to exhaustive contractions / trauma / hypoxia / etc., could in fact play a likewise, probably more important role not so much in skeletal muscle growth, maybe, but in the overall systemic response to exhaustive skeletal muscle contractions. 
  After all, Jammes et al. observed a delayed, but significant elevation of non phosphorylated HSP25 and HSP70 in skeletal and respiratory muscles, kidney, and brain. Now, of HSP70, for example, it has long been known that it exerts cardio-protective effects (Martin. 1997). In addition to its anti-apoptotic effects, it does yet also contribute to the proteolysis (=protein breaking) that's a necessary part of the continuous clean-up processes that remove the "junk" and "clutter" (defect protein structures) from your body in order to keep everything functional (Lüders. 2000). Similarly, HSP25 (aka HSPB1) exerts both cytoprotective effects due to its ability to modulate reactive oxygen species and raise glutathione levels, as well as proteolytic effects and is working hand in hand with HSP70 by inhibiting protein aggregation and stabilizing partially denatured proteins, so that they can be refolded by the former. That the latter could be of particular importants in view of the neuroprotective effects of exercise is also supported by a couple of trials in which HSPB1, to be precise, its exogenous administration or endogenous overexpression, have been evaluated as treatment or preventive strategies in ALS (Lou Gehrig's Disease), Huntington's, Parkinson's, Stroke and acute nerve injury (for an overview see table 3 in Brownell. 2012).

• 

  Figure 5: The benefit of l-carnitine is questionable, despite the fact that the serum l-carnitine in the Mg group dropped to a similar extent as in the control group; over time the carnitine depletion could however become important (Tarighat Esfanjani. 2012)

  Headaches? Magnesium and l-carnitin help! At a dosage of 500mg/day magnesium oxide, alone did already have significant beneficial effects on the occurrence of migraine in  106 females and 27 males volunteers who were diagnosed with headache according to the International Headache Society criteria, were between the age of 18 and 55 years old and "had severe and continual headache lasting from 4 to 72 h, unilateral and pulsating headaches with moderate or severe intensity, migraine with or without aura, at least two attacks per month, headaches which were aggravated by routine physical activity and associated with nausea and/or photophobia, and phonophobia" (Tarighat Esfanjani. 2012).
  So, if that sounds like you (I don't hope it does) magnesium should be the least you should take, the additional 500 mg/day L-carnitine is questionable - just as whether ALCAR may have provided greater benefits. Apropos, you do realize that this is neither transdermal nor any fancy chelated magnesium or at least magnesium citrate that did the trick? Yeah, right: The same "worthless" (put name of random nutrition guru, here) mg-oxide you find in the cheapest fizzy tablet from the supermarket did the trick!

If you are now thirsty for more, I suggest you check out the SuppVersity Facebook Wall (which is by the way updated several times a day), like the career-boosting information that sacrificing sleep in order to study is a bad idea, that Caucasians, compared to Asians, lose weight relatively easily, but have a hard time getting rid of their bellies, or, if all that ain't for you, how the wise producers of "functional foods" are planning to add a little wood aka methylcellulose into your yogurts and smoothies to curb the cravings you probably would not have, if they had not removed all the fat from it, before ;-)

 References:

• Brownell SE, Becker RA, Steinman L. The protective and therapeutic function of small heat shock proteins in neurological diseases. Front Immunol. 2012;3:74. Epub 2012 May 1.
• Chang L, Villacorta L, Li R, Hamblin M, Xu W, Dou C, Zhang J, Wu J, Zeng R, Chen YE. Loss of Perivascular Adipose Tissue upon PPARγ Deletion in Smooth Muscle Cells Impairs Intravascular Thermoregulation and Enhances Atherosclerosis. Circulation. 2012 Aug 1. 
• Chi A, Tang L, Zhang J, Zhang K. Chemical Composition of three Ingredients of Polysaccharides from Gynostemma pentaphyllum and Comparison of their Antioxidant Activity in Skeletal Muscle of Exhaustive Exercise Mice. Int J Sport Nutr Exerc Metab. 2012 Aug 14.
• Citelli M, Bittencourt LL, da Silva SV, Pierucci AP, Pedrosa C. Vitamin A Modulates the Expression of Genes Involved in Iron Bioavailability. Biol Trace Elem Res. 2012 Apr 14. 
• Fitzgibbons TP, Kogan S, Aouadi M, Hendricks GM, Straubhaar J, Czech MP. Similarity of mouse perivascular and brown adipose tissues and their resistance to diet-induced inflammation. Am J Physiol Heart Circ Physiol. 2011 Oct;301(4):H1425-37.
• Jammes Y, Steinberg JG, By Y, Brerro-Saby C, Condo J, Olivier M, Guieu R, Delliaux S. Fatiguing stimulation of one skeletal muscle triggers heat shock proteins activation in several rat organs: the role of muscle innervation. J Exp Biol. 2012 Aug 16.  
• Leber B, Tripolt NJ, Blattl D, Eder M, Wascher TC, Pieber TR, Stauber R, Sourij H, Oettl K, Stadlbauer V. The influence of probiotic supplementation on gut permeability in patients with metabolic syndrome: an open label, randomized pilot study. Eur J Clin Nutr. 2012 Aug 8.
• Lee B, Jung JH, Kim HS. Assessment of red onion on antioxidant activity in rat. Food and Chemical Toxicology. August 10, 2012.
• Lüders J, Demand J, Höhfeld J. The ubiquitin-related BAG-1 provides a link between the molecular chaperones Hsc70/Hsp70 and the proteasome. J Biol Chem. 2000 Feb 18;275(7):4613-7. 
• Lv, X.Y., Li, J., Zhang, M., Wang, C.M., Fan, Z., Wang, C.Y., Chen, L., 2010. Enhancement of sodium caprate on intestine absorption and antidiabetic action of berberine. AAPS.PharmSciTech. 11, 372–382. 
• Martin JL, Mestril R, Hilal-Dandan R, Brunton LL, Dillmann WH. Small heat shock proteins and protection against ischemic injury in cardiac myocytes. Circulation. 1997 Dec 16;96(12):4343-8. 
• Moschonis G, Chrousos GP, Lionis C, Mougios V, Manios Y. Association of total body and visceral fat mass with iron deficiency in preadolescents: the Healthy Growth Study. Br J Nutr. 2011 Nov 16:1-10.
• Ruan CH, Dixon RA, Willerson JT, Ruan KH. Prostacyclin therapy for pulmonary arterial hypertension. Tex Heart Inst J. 2010;37(4):391-9. 
• Tarighat Esfanjani A, Mahdavi R, Ebrahimi Mameghani M, Talebi M, Nikniaz Z, Safaiyan A. The Effects of Magnesium, L-: Carnitine, and Concurrent Magnesium-L-: Carnitine Supplementation in Migraine Prophylaxis. Biol Trace Elem Res. 2012 Aug 17. 
• Yoshikava O, Ebata Y, Tsuchiya H, et al. A retinoic acid receptor agonist tamibarotene suppresses iron accumulation in the liver. Obesity. 2012 Aug.
• Zhanga M, Lvc X, Lia J, Menga Z, Wangd Q, Changa W, Lia W, Chena L. Sodium caprate augments the hypoglycemic effect of berberine via AMPK in inhibiting hepatic gluconeogenesis. Molecular and Cellular Endocrinology. 16 August 2012

Speed Up Your Regeneration and Propel Your Gains by Taking a HOT Bath Bath 2-Days Before Arduous Workouts

Image 1: Are women tougher than men, because bathe more often? If you define toughness by your muscles resistance to eccentric exercise damage, the answer could be "YES!"

If you listened to Brooks, Carl and me on Super Human Radio, yesterday (download the podcast), you may remember me stating that 48h appears to be a good rule of thumb, as far as the rest periods between workouts for individual body parts are concerned (this assumes that you are young, healthy, reasonably conditioned and lift heavy). A recently published paper by Chad D. Touchberry  does now suggest that there may be another 48h window before your workout (Touchberry. 2012). One you would use a priori to improve your recovery a posteriori - preconditioning in a hot bath for 20 min at 41°C, 48h before a hard workout or competition!

Eccentric treadmill running = maximum muscle damage

At least in a rodent model, those 20 min of heat exposure in 41°C warm water lead to statistically highly significant decreases in exercise induced muscle damage, improved and accelerated the recovery process and, contrary to what could be assumed based on previous research on the expression of heat proteins (Frier. 2007), did not hamper, but promote muscle gains in response to an exercise protocol consisting that consisted of running at 18m/min down a -16% grade for 5 min. This protocol has been used as a model for injurious exercise repeatedly in the past and constitutes one of the standard tests in rodent, but also in human studies (e.g. Pumpa. 2011).

Figure 1: Creatine kinase (CK) activity and immune cell infiltration after eccentric exercise with (EE+HS) and without (EE) preconditioning via hot bath 48h before (data calculated based on Touchberry. 2012)

As the data in figure 1 goes to show, the hot bath (EE+HS) had significant ameliorative effects on both the muscle damage (indicated by CK and the black sections in the H&E-stained soleus muscle cross-sections in figure 1, right), of which the researchers state that, despite the fact that "the mechanism by which heat shock protects skeletal muscle from damage is currently unknown", the protection of skeletal muscle against damage in mice overexpresssing HSP70 (McArdle. 2004a) as well as the differential HSP72 elevation in the HS group 2h and 48 h following exercise collectively

[...] suggest that HSP72 or another heat sensitive protein (i.e.,alphaB-crystallin) may play a role in mediating cytoprotection of skeletal muscle cells.

Moreover, Touchberry et al. explain the existing discrepancies between their own results and previous results by Mc.Ardle et al. (Mc. Ardle. 2004b), who did not find reduced muscle damage after pre-treatment with hsp-inducing concentric exercise 10h prior to the (in my humble opinion questionable) in-vitro application of eccentric strain to skeletal muscle tissue, with the "greater time for HSP accumulation prior to the exercise stressor" in their (48h) vs. the Mc.Ardle study (10h), which is obviously yet another indicator that rest is one of the most under-appreciated determiners of workout efficiency (cf. my words on SHR ;-)

Regeneration is one thing, but are muscle gains another?

Now, I am well aware that one of the main reasons regeneration isn't sexy, is that it does not trigger the phosphorylation of Akt, m-TOR and all the rest of the sciency terms with which laymen are bombarded by the supplement industry these days.

Figure 2: Total protein, new myosin heavy chain (MHCNEO) content and p-Akt expression in soleus muscle 2h and 48h after the eccentric exercise bout (data calculated based on Touchberry. 2012)

The study at hand does even show that heat pre-treatment will actually reduce, not promote the phosphorylation of AKT 48h after the exercise bout (cf. figure 2). If you do yet take into account that the total protein concentration and MHCneo (novel myosin-heavy-chain motor proteins) content in the soleus muscle of the rodents was increased profoundly, I guess you will have to agree that it is unlikely that less damage, a faster regeneration, and as a consequence less need for protein to be recruited via p-AKT only to repair the damage is going to propel, not diminish your gains!

Practical implications & open questions

Once again, the obvious message of this study is: Not he who trains the most, but he who regenerates and rebuilds the best, gains the most! And adequate rest aside, preconditioning in a hot (not a "cold thermogenic" bath ;-) can help dampen the exercise induced damage and accelerate your recovery.

Note: In February 2012, Bayley et al. published a paper that shows that the application of passive heat in form of a 42°C hot water bath for 40min immediately prior to a bout of HIT leg extensor exercises reduced the time to fatigue in seven healthy men by a whopping -36%  (Bayley. 2012). Impatience, or rather the unwillingness to grant your body the time it needs to recover is thus detrimental even if the stressor is "just" a hot bath!

Whether the same would be true if you train today and do the hot water immersion immediately, 2h, 10h or 12h post and thus 48h, 46h, 38h or 36h before your next workout is yet about as questionable, as whether or not similar effects could be elicited by switching back and forth between light and heavy days every 48h.  Both may appear likely, but aside form the fact that the optimal timing or workout intensity will still have to be elucidated, are still in the state of an interesting research hypothesis, not more, but also not less.

Update - Suggested reading: Since there have been questions pertaining to the usefulness of hydrotherapy post-workout, i.e. as a means of "classic" re- and not "precovery", I thought I rather refer you directly to my buddy Sean's E-book on the issue. Here is a snippet from the book

Image 2: Don't miss Sean's free e-book on classic hydrotherapy

Quick Hit Summary Water therapy is a common modality to enhance muscle recovery post workout. Sitting in chest high thermoneutral water for 20-30 minutes may accelerate waste removal while increasing blood flow to working muscles. Cold, hot and contrast water temps are also commonly used to assist recovery. The goal of cold water therapy is to reduce inflammation whereas hot water purportedly increases muscle blood flow. Contrast water therapy involves alternating between hot and cold water baths to induce a vaso-pumping effect. Current evidence does not support the theory behind these latter 2 therapies simply because the heat (from the water) is incapable of penetrating more than a couple centimeters into the skin. Thus, there is no stimulus to increase muscle blood flow

You can get this e-book alongside two other books for free if you register for Sean's newsletter, which is, take my word on it (!), not a weekly advertisement piece!
 
References:

1. Bailey SJ, Wilkerson DP, Fulford J, Jones AM. Influence of passive lower-body heating on muscle metabolic perturbation and high-intensity exercise tolerance in humans. Eur J Appl Physiol. 2012 Feb 10.
2. Briese E. Normal body temperature of rats: the setpoint controversy. Neurosci Biobehav Rev. 1998 May;22(3):427-36. Review. 
3. Frier BC, Locke M. Heat stress inhibits skeletal muscle hypertrophy. Cell Stress Chaperones. 2007 Summer;12(2):132-41. 
4. McArdle A, Dillmann WH, Mestril R, Faulkner JA, Jackson MJ. Overexpression of HSP70 in mouse skeletal muscle protects against muscle damage and age-related muscle dysfunction. FASEB J. 2004a Feb;18(2):355-7.
5. McArdle F, Spiers S, Aldemir H, Vasilaki A, Beaver A, Iwanejko L, McArdle A, Jackson MJ. Preconditioning of skeletal muscle against contraction-induced damage: the role of adaptations to oxidants in mice. J Physiol. 2004b Nov 15;561(Pt 1):233-44. Epub 2004 Aug 26.
6. Pumpa KL, Fallon KE, Bensoussan A, Papalia S. The effects of Lyprinol(®) on delayed onset muscle soreness and muscle damage in well trained athletes: a double-blind randomised controlled trial. Complement Ther Med. 2011 Dec;19(6):311-8.
7. Touchberry CD, Gupte AA, Bomhoff GL, Graham ZA, Geiger PC, Gallagher PM. Acute heat stress prior to downhill running may enhance skeletal muscle remodeling. Cell Stress Chaperones. 2012 May 17. [Epub ahead of print]