When Rodents Squat, Scientists Gain Insights into How Muscles Grow. IGF-1 Response to Exercise Does Matter - Locally, not Systemically, of Course!

You want to build big wheels? Look no further get yourself the "Squat T-Bar" with integrated 15mA electrical 'motivator' (Aguiar. 2012)

"A rodent study investigating strength workouts?" Yeah, I know it does not sound like that would be in any ways news-worthy, but if you take a look at the image on the right, you will immediately realize: This study is different! Instead of using a treadmill or simply stitching down (or rather up) one of the hindlimbs of the rodents to induce a chronic overload on the other one (don't laugh, many rodent studies have done just that), the study at hand (Aguiar. 2012), which is going to be published in the next issue of the International Journal of Sports Medicine, used a not innovative, but unfortunately largely forgotten (or overlooked?) torturing device that has been developed by Japanese researchers roughly 20 years a ago (Tamaki. 2012).

The rodent torture... ah pardon squat rack ;-)

After being fitted with a canvas jacket in a way that would enable the researchers to limit the twisting and flexion of their torsos (no, that was not a weight lifting belt ;-), the 32 male Wistar rats (80 days old, 250–300 g) were suspended in a standard position on their hind limbs and "encouraged" to exercise by "electrical stimulation [...] that was applied to the rat’s tail through a surface electrode"  (Aguiar. 2012).

Using their neat little toy, the eight researchers from the University Estadual Paulista, in Botucatu, Brazil, were able to submit the rats to a relatively realistic progressive resistance training regimen for either 8 or 12 weeks. Three times per week each rodent had to do 4 sets  of squats for 10-12 repetitions at 65-75% of its individual 1-RM (maximal weight the rodent could handle). During the study period, Aguiar et al. adjusted the weights twice a week to ensure the same training intensity throughout the experiment (something I would highly recommend to anyone of you, as well; try to pack on 1.25lbs - 2.5lbs at least every other week).

Figure 1: Body weight, muscle weight (plantaris, only) and food intake relative to body weight of the control (C8, C12) and trained (T8, T12) rats before and after the 8-week (C8, T8) and 12-week (C12, T12) intervention (data adapted from Aguiar. 2012)

As you can see in figure 1, this minimalist approach to leg training lead to an increase in both body weight and muscle weight that may initially look as if it was strongly linear. You do yet have to be careful about statements like that, because (a) the rodents did gain weight irrespective of whether they were training or not (80 day old rats are still growing!), so comparing the four bars next to each other and saying "yep, linear!" is not feasible, because this would mean linear as in not training for eight weeks < training for 8 weeks < not training for 12 weeks < training for 12 weeks, which is obviously nonsensical. That being said, there is simply (b) insufficient data to say anything about the linearity -- after all, we do have only three data points per group.

"All groups started the experiment with similar body weight. There was a significant increase (p < 0.05) in the body weight of the 4 groups in the resistance training program (C8: 35.5 %; T8: 27.7 %; C12: 46.9 %; and T12: 40.1 %) and final body weights were not significantly (p > 0.05) different between groups. Furthermore, no significant (p > 0.05) differences in the weekly food intakes were observed between the groups."(Aguiar. 2012)

What does yet stick out, is that the obviously age-dependent weight gain in the control groups C8 and C12 did not increase the weight of the plantaris muscle to a weight anywhere near to the muscle weight, the rats in the trained groups achieved.

Muscle gains and strength gains went hand in hand

In the rats who were subject to the three-times-per-week exercise regimen, on the other hand, those increases in muscle size went hand in hand with highly significant improvements in 1-RM squat power; While all groups had begun the training protocol with similar absolute 1-RMs of ~450g (that's about 130% body weight, pre) ...

"[...] training for 8 and 12 weeks promoted a significant (p < 0.05) increase in the RM/BW ratio in the T8 (pre- vs. post-training: 35.7 % increase, p < 0.05) and T12 (pre- vs. post-training: 57.1 % increase, p < 0.05) groups, while no statistical (p > 0.05) difference was observed in their respective control groups." (Aguiar. 2012)

Consequently, the ratio of 1-RM to body weight was 36.1 % and 57.7 % higher in the groups who had been training fot the last 8 or 12 weeks than in the lazy controls and the time-effect yielded another +22% increase in strength in those rodents who trained for 12 and not just 8 weeks.

Figure 2: Strength gains (left) and increases in cross sectional area, as well as intramuscular IGF1, myogenin and myoD expression (data adapted from Aguiar. 2012)

Now you may have heard all that before, what really makes this study stand out, however, is the observation of statistically highly significant correlations of intra-muscular IGF1, myogenin and myoD  mRNA expression, which speaks in favor of my previous hypothesis (read up on that in the Intermittent Thoughts on Building Muscle) that muscle growth is triggered, driven and maintained almost exclusively at a local level.

What are myogenin and myoD? Both are myogenic regulation factors with myogenin actually being part of the myoD family of transcription factors that will make stem cells develop into myocytes (myo D is highest in recently activated satellite cells).

So, when you are looking for "hormonal" (or other pro-anabolic) ghosts (Phillips. 2012), it is imperative to look for them right where the spook, or, in this case, the muscle building magic happens. If you do just that (see figure 2) and correlate the intra-muscular mRNA expression of IGF-1, myogenin and myoD, you will find the "ghostly" explanation for strength and size gains, as well as the confounding structural changes in the architecture of the muscle, with corresponding correlations between the increases in muscle cross-sectional area (CSA) of r = 0.85 (p = 0.0001), r = 0.87 (p = 0.0001) and r = 0.88 (p = 0.0001) for myoD, myogenin and IGF-1, respectively.

Fiber type changes take their time and occur only within the type II spectrum

A neat side-finding, which is actually no news, though, pertains to the fiber-type conversions that took place in response to the exercise regimen. Firstly, the scientists confirmed the notion that these changes occur exclusively within a certain fiber type. In other words, while Aguiar et al. observed conversions from the metabollically more flexible type IIX/D to the highly glycolytic (power) IIA type, no conversions of the highly oxidative type I to type II fibers were observed. And though the results would generally suggest that fiber IIX/D-to-IIA type conversion, as they 

"[...] also appear to occur during endurance training in humans, so that it would [be] reasonable to think that any exercise stimulus (e. g., endurance or strength) that is sufficient in duration and/or intensity can potentially induce conversions within the fast fiber population from type IIX/D to type IIA" (Aguiar. 2012),

the time-frame in the course of which these changes took place -- namely 12 weeks -- would confirm that the common fear of strength and endurance athletes could provoke negative structral adaptations from doing a "cardio" or "strength" workout from time actually is actually unwarranted. Neither will the former turn a powerlifter into a weakling, nor will the latter make a marathon runner "bulky". Both powerlifter and marathoner are on the contrary going to benefit from the conditioning effect and increase in strength, respectively -- not to mention the important effects on overall health both and not as mainstream stupidity will tell you only the powerlifter can derive from, figuratively speaking, "killing some game in the other's territory"

Bottom line: More food for intermittent thoughts on building muscle ;-)

Figure 3: Correlations between acute GH (A), free testosterone (B), IGF-1 (C)  and cortisol (D) responses (area under the curve—AUC) and gains in type II fibre CSA (Burd. 2012).

Eventually, this study is an excellent example of a way to design a rodent study in a way that will render its results actually meaningful. And what's more, in this particularly case these results are not just meaningful, but can also help us to make some sense of a couple of things we have not fully understood / appreciated, as of yet.

What I am particularly thinking about here, is the contrast between the in-vitro effects of IGF-1 and the (more or less absent) real-world effects of the IGF-1 response to exercise (=systemic increase), as it was observed by West and Phillips in a 2012 study. In their well-powered longitudinal study, neither the acute increase in systemic testosterone, nor the exercise induced increases in systemic IGF-1 showed significant correlations with the gains in type II CSA in a cohort (n = 56) of young men in response to 12 weeks of resistance training (West. 2012; see figure 3).

Another interesting finding of the West study was that, contrary to the circulating testosterone and IGF-1 levels, GH and cortisol did show direct correlations with increased muscle cross sectional areas in type II fibers.

And while the former correlation may be explained by the influence of growth hormone (GH) on the local expression of IGF-1 (Hameed . 2004), there is another open question left: How does cortisol actually figure in here? I mean, the chronic elevation / exogenous adminstration of cortisol, has been show to do the exact opposite, i.e. it decreases the local IGF-1 mRNA expression (Inder. 2010).

Figure 4: Graphical summary of what you should have learned Intermittent Thoughts on Building Muscle ... you didn't 'cause you are new to the SuppVersity or simply forgot about it? No problem read the preliminary summary and browse the individual chapters here!

What was missing in the Inder study, however, was the exercise component: Working out does not just exert protective effects against the negative side effects of the provision of exogenous "cortisol" (in this case Dexamethason), as they were observed in the afore referenced study by Inder et al., exercise will also lead to profound increases in local IGF-1 mRNA expression (e.g. +60% in Bamann. 2001), despite the fact that it will also increase the release of the falsely vilified anti-inflammatory glucocorticoid, cortisol... acute vs. chronic, local vs. system, peak values and amplitudes vs. plateaus and AUC values - you got to keep all these contrastive, yet complementary pairs in mind, when you are thinking about the endocrine and intracrine (within the cell) mediators of skeletal muscle hypertrophy.... what? Sounds familiar? Well, you must have been following the Intermittent Thoughts on Building Muscle, then ;-)

References:

• Aguiar AF, Vechetti-Júnior IJ, Alves de Souza RW, Castan EP, Milanezi-Aguiar RC, Padovani CR, Carvalho RF, Silva MD. Myogenin, MyoD and IGF-I Regulate Muscle Mass but not Fiber-type Conversion during Resistance Training in Rats. Int J Sports Med. 2012 Oct 11.
• Bamman MM, Shipp JR, Jiang J, Gower BA, Hunter GR, Goodman A, McLafferty CL Jr, Urban RJ. Mechanical load increases muscle IGF-I and androgen receptor mRNA concentrations in humans. Am J Physiol Endocrinol Metab. 2001.
• Ding H, Gao XL, Hirschberg R, Vadgama JV, Kopple JD. Impaired actions of insulin-like growth factor 1 on protein Synthesis and degradation in skeletal muscle of rats with chronic renal failure. Evidence for a postreceptor defect. J Clin Invest. 1996 Feb 15;97(4):1064-75. 
• Inder WJ, Jang C, Obeyesekere VR, Alford FP. Dexamethasone administration inhibits skeletal muscle expression of the androgen receptor and IGF-1--implications for steroid-induced myopathy. Clin Endocrinol (Oxf). 2010 Jul;73(1):126-32.
• Phillips SM. Strength and hypertrophy with resistance training: chasing a hormonal ghost. Eur J Appl Physiol. 2012 May;112(5):1981-3-
• Sculthorpe N, Solomon AM, Sinanan AC, Bouloux PM, Grace F, Lewis MP. Androgens affect myogenesis in vitro and increase local IGF-1 expression. Med Sci Sports Exerc. 2012 Apr;44(4):610-5.
• Tamaki T, Uchiyama S, Nakano S. A weight-lifting exercise model for inducing hypertrophy in the hindlimb muscles of rats. Med Sci Sports Exerc. 1992 Aug;24(8):881-6.
• West DW, Phillips SM. Associations of exercise-induced hormone profiles and gains in strength and hypertrophy in a large cohort after weight training. Eur J Appl Physiol. 2012 Jul;112(7):2693-702. 

High Fat vs. High Carb and How the Tiny Word "Synthetic" May Turn Out to Be an Epic Game Changer That Puts a HUGE Question Mark Behind "If It Fits Your Macros"

Even if both "Fit Your Macros" you should know better than to select the "fruit" loops (where is the "fruit" in those loops anyway?).

A war is raging! Well, at least in the Internet the "battle" between the low-carb revolutionists and the low-fat veterans does sometimes in fact resemble an epic battle between god and evil... at least that's what the combatants believe.

As of late it seems as if the rebels, i.e. the low-carbers were getting the upper hand and that despite the constant supplies the low fat veterans are getting from their friends in the medical establishment - friends who pay for studies the veterans to agrue how stupid and off base the rebels' assumption that "low carbing" would help us to solve the obesity epidemic actually actually were.

Don't worry this post is not a war epic ;-)

I know, up to this point, all this may not have sounded much like a SuppVersity article, but this will change now that we are about to take a look at a soon-to-be-published paper by Bérengère Benoit et al. from the Lyon University (Benoit. 2013).

What do these Jerusalem artichokes, agave, bananas, burdock, camas, chicory, coneflower, costus, dandelion, elecampane, garlic,jicama, Leopard's-bane, mugwort, onion, wild yams, yacon and a whole host of other foods have in common? Right! They contain inulin. Whether you will be able to get a whopping amount of 10% inulin in your diet w/out the use of supplements or "enriched" foods, is yet as questionable as how beneficial this actually is for friends of physical culture (read more)

The French researchers started out with the hypothesis that the metabolic effects of a diet does not simply depend on its macro-nutrient composition. Instead, they made the SuppVersity standard assumption that the food quality is about as important as food quantity and assumed that negative effect of one of the standardized synthetic high fat rodent diets (sy-HFD) consumption would be

"[...]impacted by the choice of the control diet using 2 control diets that are typically used in HFD-induced obesity protocols. The specific research objectives were to test the impact of diets on typical parameters studied in HFD-induced obesity protocols: body weight gain, fat accumulation in tissues, alteration of insulin sensitivity, markers of inflammation, and markers of plasma endotoxemia." (Benoit. 2013)

And this means? Well, think about it as if you wanted to analyze the quality of the shiny new iPhone. Obviously, it will be all the shinier the trashier your baseline comparison is - right?

The French scientists assumed something very similar may apply for the high fat diets. Depending on whether you compare them to a "healthy" or a trashy diet, the outcome of your study and the message "Low carb is..." will be different. The same obviously goes the other way around. If you have a "high carb" diet that's all fructose and nothing else, your outcome will be different and you will draw different conclusions and may make diametrically opposed recommendation.

Ok, I got to be honest with you...

... this is not - at least not yet - the study that compares what you probably understand when I say "low carb" to what you probably think of, when I say "low fat". So this is not something like 25/5/70 (protein, carbs, fats) vs. 25/70/5 (protein carbs, fats). Rather than that, Benoit et al. used those "high fat" diets you see in 99% of the corresponding rodent studies. Diets that are high in both carbohydrates (45%) and fats (40%) - values expressed in weight units - and would thus imho qualify as "low protein" diets.

Figure 1: Differential effects of synthetic low fat (sy-LFD) and high fat diet (sy-HFD) on lean mass, fat mass, insulin, triglycerides, cholesterol and the amount of free fatty acids in the blood of the rodents; all data expressed relative to the corresponding values of the rodents in the regular chow group (Benoit. 2013)

What the researchers did though was to give their analysis a twist by including not one, but two control diets. One containing a synthetic and one containing natural low fat chow - both of them with identical macro-nutrient composition (18, 70, 12% - protein, carbs, fats), but with the former, the synthetic low carb chow being based on the same artificial (in this case this just means that the combination of nutrients was artificial and would not occur like that in nature) ingredients as the synthetic high fat diet.

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This is hilarious, right? Identical macro make, up totally different results? Yep, that's right and it should be reason enough for us to look into the differences. So let's see what we've got

• 

  According to Wood et al. (1988) black pepper contains between 3-8% piperine. This means that 4 teaspoons of it should help you combat abdominal fat (-16% on cornstarch diet in rodent study) - at least according to these previously reported results.

  Barley, wheat, corn, those are the main carbohydrate sources in the regular low fat chow. In the synthetic diet, however it's corn starch, succrose and a tiny bit of lactose.
• Soybean (not oil, but whole!) and fatty fish solubles, those are the main fat sources in the natural diet. The synthetic diet on the other hand contains soy bean oil, lard and milk fat.
• Wheat bran that's the major source of fiber in the natural diet. It's synthetic counter-part on the other hand features pure wood aka cellulose. 
• Inert proteins, i.e. those which are already present in the plant material in the regular chow diet are the only protein sources in the regular diet. The synthetic diet on the other hand features casein of which numerous previous studies have shown that it appears to promote the mass (lean and fat) accrual in rodents.

It is thus quite obvious: Hitting your macros is not all that counts. It's not all that counts for rodents and you can bet that it ain't all that counts for human beings.

So what's the real take home message then?

• From a science perspective: At least the rodent-part of the (hi-)story about the good and bad effects of low fat and/or low carb diets does have to be rewritten, now that we know that we have been fooling ourselves with figures that are worthless unless you know exactly what (which foods) they represent. Ever since the late 1990s we know for example that a "natural" high fat diets with a high amount of whole eggs will delay (not accelerate) the natural decline in insulin sensitivity and that in rats (Berdanier. 1998)!
  
  So, have the synthetic rodent diets fooled us? Probably yes. And what about the synthetic Standard American Diet? Well, it may not have fooled, but certainly killed us - at least several millions of us.
   
• From a real world perspective: Actually I already said, it, but I guess I will simply repeat that quality counts and macros are nice numbers with little meaning without at least a broad guideline (like: "Eat whole foods only!") on where you get them from.

Personally, I am curious whether anyone will actually take the results of this study at heart and finally throw the synthetic rodent chow away... you don't think so? Well, me neither.

References: 

• Benout B, et al. High-fat diet action on adiposity, inflammation, and insulin sensitivity depends on the control low-fat diet. Nutrition Research. 2013 [epub ahead of print]
• Berdanier CD, Kras KM, Wickwire K, Hall DG. Whole-egg diet delays the age-related impaired glucose tolerance of BHE/Cdb rats. Proc Soc Exp Biol Med. 1998 Oct;219(1):28-36.
• Wood AB, Barrow ML, James DJ.  Piperine determination in pepper (Piper nigrum L.) and its oleoresins - a reversed-phase high-performance liquid chromatographic method. Flavour Fragr. J., 3: 55–64.