Vitargo™, Red Bull™ + Co. Research - Are They Worth It? Beef Can Keep Up W/ Whey For Gains! "Creatine Loading" = Too Much of a Good Thing - ISSN Research Review '15 #1

When you're running on a treadmill it obviously takes more than one serving of Red Bull or other commercial energy drinks to kickstart your workout performance | learn more below.

Initially, I wanted to cherry pick only the most interesting study results that were presented in form of poster presentations at the Twelfth International Society of Sports Nutrition (ISSN) Conference and Expo in 2015. After looking at the research that is - as of now - only available in form of (albeit often detailed) abstracts, I decided that there are way too many interesting studies to cover only three of them in depth or all of them only cursory. Accordingly, I decided to start a SuppVersity Mini Special with this being the first out of 3-4 issues in which I will briefly discuss the most significant results of those of the roughly two dozen studies, I (a) believe are of greatest interest to you and (b) feel comfortable talking about without having all the details in form of the still to be published full texts.

Read more about ISSN and other studies at the SuppVersity

Vitargo, Red Bull, Creatine & More | ISSN'15 #1

Pump Supps & Synephrine & X | ISSN'15 #2

High Protein, Body Comp & X | ISSN'15 #3

Keto Diet Re- search Update | ISSN'15 #4

The Misquantified Self & More | ISSN'15 #5

BCAA, Cholos-trum, Probiotics & Co | ISSN'15 #6

• The latest research on Vitargo(TM) -- The mere fact that the latest study on Vitargo(TM) was presented in "three servings", on the latest ISSN meeting, i.e. (1) on the glucose and insulin response (Almada. 2015), (2) on the incretin response (Anzalone. 2015) and (3) on the power output during a subsequent bout of resistance exercise (Van Eck. 2015), could raise some concerns about the objectivity of the results, but is as Patrick Jacobs kindly reminded me common scientific practice.. So, let's put the skepticism aside and take a look at the study design and results.
  
  

  

  Post-Workout Glycogen Repletion | Read my overview article.

  Sixteen resistance trained men participated in a double-blind, placebo-controlled, randomized crossover study, which consisted of three testing sessions, each separated by one week. In sessions 1-3, subjects completed a glycogen depleting cycling bout of 60 minutes at 70% VO2 max, followed by six, one-minute sprints at 120% VO2 max.
  
  Immediately post-exercise subjects ingested a placebo (PLA), or a low molecular (LMW) or high molecular weight (HMW) CHO (=Vitargo(TM)) solution (10%) providing 1.2g/kg body weight CHO; assigned randomly. Blood samples were taken prior to ingestion and every ten minutes for 2h.
  
  For the "first" and "second" serving of the study this was enough. These mini-presentations dealt with the insulin, glucose and incretin response to the two supplements, only. For the "third serving", however, the scientists included performance data from a subsequent bout of exercise, during which the participants did 5 sets of 10 repetitions of back squats (75% 1RM) "as explosively as possible" (if subjects paused for more than 2 seconds or were unable to complete a rep, resistance was lowered by 13.6 kg | Van Eck. 2015).
  

  

  Figure 1: Overview of the most relevant results (LMW = low molecular weight CHO vs. HMW = Vitargo (TM) high molecular weight CHO) from Almada (2015), Anzalone (2015) and Van Eck (2015).

  As you can see in my overview of the most relevant results, the scientists did not find practically meaningful differences in study I-II. In study III, which compared the effects of low to high molecular weight carbohydrates (LMW vs. HMW) on squat performance 2h after the glycogen-depleting workout, this was slightly different:

  "HMW conferred a likely beneficial effect in Sets 4 and 5 (92.5% and 88.7% likelihood, respectively), compared to PLA; while ingestion of LMW conferred only a possibly beneficial effect (68.7%) and likely beneficial effect (83.9%) in Sets 4 and 5, respectively" (Van Eck. 2015).

  And still, if you read the conclusion, "the ingestion of a HMW CHO solution providing 1.2 g/kg CHO may allow athletes to sustain power output in a subsequent resistance training session when time between training sessions is limited" (Van Eck. 2015), carefully, you will notice the words "likely" and "possibly" which signify the putative nature of the effect. What may be even more relevant than that, is yet that few of you will do glycogen-depleting exercises at 4:00 pm and hit the gym again for an intense leg workout at 6:00 pm. Accordingly, the practical relevance of the "sustained power output" Van Eck et al. observed is probably restricted to a small group of professional athletes. For people who fall into this category or strength athletes training twice a day, though, using Vitargo (TM) may in fact offer significant benefits.
• Beef and whey support lean mass gains similarly effectively -- If you are asking yourself if beef isolate protein is a good or at least decent replacement for whey, the post-workout protein supplementation "gold standard" some people can't use due to its (albeit low) lactose content, a recent study from the University of Tampa (Sharp. 2015) has the answer you are looking for.
  

  

  Figure 2: Relative improvements in muscle size (hypertrophy) and body fat (fat loss) in response to beef isolate or whey protein supplementation; expressed relative to maltodextrin placebo (Sharp. 2015).

  As the data in Figure 2 tells you, it will make a good replacement! If we go by the average increase in lean mass and loss of fat mass, the beef isolate that was consumed in amounts of 2x20g per day either immediately after each of the 5 weekly workouts (3 resistance training, 2 cardio; 8 weeks total, daily undulating periodization) or at a similar time in the day, you may even argue that the beef protein had the overhand over its "milky" competitor. If we take the individual variations into account, though, the 1% lean mass and almost 3% fat loss advantage (DXA values) of the beef protein turns out to be statistically non-singifican.
  
  The same goes for differences in strength gains, of which the researchers found that they were identical not just in the two supplement, but also in the supplement and control groups. The lack of additional power during the bench press test may, as the researchers point out, be ascribed to both increases in neural and morphological adaptations" (Sharp. 2015) which would "negate" (ibid.), or as I would phrase it, 'override' potential additive effects of any of the protein supplements (whey and beef, alike).
• Energy drinks a waste of money on the treadmill? At first sight, the results of the latest study by Sanders et al. (2015) do in fact suggest that energy drinks were a total waste of money for those of you who are consuming them before a regular cardio workout on the treadmill. After all, none of the tested drinks lead to statistically significant improvements in either perceived treadmill exercise performance or running economy assessed via oxygen consumption at 70% treadmill exercise.

In contrast to treadmill running, the performance during a cycling time-trial can be improved by the consumption of an energy drink - a potential explanation for the difference may be that the subjects in the Ivy study consumed 2x  more Red Bull than the subjects in Sanders' study.

Energy drinks don't work? Well, the overall research shows a more diverse picture. While a previous study by Astorino et al. (2012) and a similar study by Candow et al. (2009) that tested the effects of Red Bull on repeated sprint performance and its effects on time to exhaustion, respectively, yielded similarly disappointing results, Ivy et al. (2009) and Forbes et al. (2007) found benefits. More specifically, the researchers observed significant increases in upper body muscle endurance (yet no effect on anaerobic peak or average power during repeated Wingate cycling tests in young healthy adults | Forbes. 2007) and improved cycling time-trial performance (without concomitant increase in perceived exertion | Ivy. 2009) - albeit with 2x more Red Bull than in the study at hand (500ml vs. 250ml).

• Now, some of you may argue that all you care about when you buy an energy drink is that it makes it easier for you to hit your target time on the treadmill. Well, I can understand that, but in view of the fact that neither of the caffeine laden 8.4 oz. Red Bull®, 16 oz. Monster Energy ®, 2 oz. 5-hour ENERGY® drinks affected the subjects subjective rates of perceived exertion, it does appear questionable that these drinks can actually help you.
  
  It does thus stand to reason that Sanders et al. conclude that the "results [of their latest study] do not support manufacturers' claims regarding their product's ability to boost performance" (Sanders. 2015). The scientists are yet also right that it would be necessary to find out whether time trial or time to exhaustion sprint and endurance performance benefit, as respective studies may be better suited to reliably "assess if these energy drinks can, in fact, improve exercise performance" (ibid.) - and in view of the fact that previous studies with corresponding outcomes yielded conflicting results (see blue box above), I can fully subscribe to that: We need more (non-sponsored) quality studies ;-)
• More evidence that creatine loading is not the way to go -- In Gann et al.'s latest study, fourteen (Cr = 7, Pl = 7) non-resistance-trained (i.e. < thrice weekly, 1 year prior) men between the ages of 18-30 were randomly assigned by age and body weight to orally ingest a powdered dextrose placebo or creatine monohydrate (Gann. 2015).
  
  After baseline strength and body composition testing procedures, participants ingested creatine or placebo at a dose of 0.3g/kg lean body mass/day (≈ 20-25g/day) for a 5 day loading phase immediately followed by a 42-day maintenance phase at a dose of 0.075g/kg lean body mass/day (≈ 5-7g/day). The participants followed a periodized 4 day per week resistance-training program split into two upper body and two lower body workouts per week, for a total of 7 weeks. Blood and muscle samples were obtained at Day 0, 6, 27, and 48. Statistical analyses were performed utilizing separate two-way ANOVA for each criterion variable employing a probability level of ≤ 0.05.
  

  

  Figure 3: Don't be fooled by shiny ads! While there is evidence that some forms of creatine will be faster absorbed than creatine monohydrate, only the addition of dextrose (and ALA or baking soda) have actually been shown to increase the muscular retention of creatine in experiments (Jäger. 2011) 

  As you'd expect, the addition of creatine lead to significant increments in total body mass (p = 0.03) and lean body mass (p = 0.01). What creatine did not do, though, was to affect the amount of body fat the subjects were carrying around. The latter decreased to a similar extent in both groups in response to resistance training, alone (p = 0.001) - without any effect of creatine supplementation. Much to my personal surprise, the same was the case for the subjects' muscle strength, which was - likewise - increased to the same extent in both groups.
  
  So what? Well, in contrast to the uncommon lack of effect on muscle strength, the lack of effect on body fat is sad, but had to be expected. Both findings are yet not why this study made the SuppVersity Cut. That is or rather was Gann's observation that the loading phase lead to significant increases in of urinary creatine (p = 0.036), and urinary creatinine (p = 0.01) in the creatine group compared to placebo. This "excess amounts of serum and urinary creatine and urinary creatinine content" (Gann. 2015) provides further evidence that the (still common) practice of creatine loading is useless and 100% safe certainly only in the short term. In the long term, however, I'd highly suggest that you avoid super-dosing on creatine - I mean, why would you want to use 20g per day, when 3-5 g per day is enough (Wilder. 2001) and more than will "lose" once the creatine levels of your muscles are saturated (the exact washout time is unknown, but studies indicate it may be >40 days of consuming no creatine at all | Deldicque. 2008)?

Intra-workout BCAA supplements are marketed specifically to resistance trainees. If they do have anti-catabolic effects, though, those are - just like potential fatigue reducing effects - significantly more likely to occur in endurance trainees | learn more

What else? In the bottom line of this mini-series I will briefly reference those studies that did not make the SuppVersity Cut for various reasons. Studies like those on the benefits of BCAAs, for example (Kephart. 2015 or Mumford. 2015). For this kind of study I would need the full-text, not just the abstract to tell you how relevant conclusions like the "BCAA supplement did not appear to enhance recovery benefits compared to a CHO control", "a few areas of performance were bolstered to a point of practical importance"(Kephart. 2015) or "BCAA supplementation [...] may benefit immune function during a prolonged cycling season" (Mumford. 2015), actually are. As soon as the corresponding full papers you have published I will obviously make good for any performance-relevant information I may be missing by ignoring the abstracts, today | Comment on Facebook!

References:

• Almada, Anthony L., et al. "Effect of post-exercise ingestion of different molecular weight carbohydrate solutions. Part 1: The glucose and insulin response." Journal of the International Society of Sports Nutrition 12.Suppl 1 (2015): P30.
• Astorino, Todd A., et al. "Effects of red bull energy drink on repeated sprint performance in women athletes." Amino acids 42.5 (2012): 1803-1808.
• Anzalone, Anthony J., et al. "Effect of post-exercise ingestion of different molecular weight carbohydrate solutions. Part II: The incretin response." Journal of the International Society of Sports Nutrition 12.Suppl 1 (2015): P31.
• Candow, Darren G., et al. "Effect of sugar-free Red Bull energy drink on high-intensity run time-to-exhaustion in young adults." The Journal of Strength & Conditioning Research 23.4 (2009): 1271-1275.
• Deldicque, Louise, et al. "Kinetics of creatine ingested as a food ingredient." European journal of applied physiology 102.2 (2008): 133-143.
• Forbes, Scott C., et al. "Effect of Red Bull energy drink on repeated Wingate cycle performance and bench-press muscle endurance." International journal of sport nutrition and exercise metabolism 17.5 (2007): 433.
• Gann, Joshua J., et al. "Effects of a traditionally-dosed creatine supplementation protocol and resistance training on the skeletal muscle uptake and whole-body metabolism and retention of creatine in males." Journal of the International Society of Sports Nutrition 12.Suppl 1 (2015): P2.
• Ivy, John L., et al. "Improved cycling time-trial performance after ingestion of a caffeine energy drink." International journal of sport nutrition 19.1 (2009): 61.
• Jäger, Ralf, et al. "Analysis of the efficacy, safety, and regulatory status of novel forms of creatine." Amino Acids 40.5 (2011): 1369-1383.
• Kephart, Wesley C., et al. "Ten weeks of branched chain amino acid supplementation improves select performance and immunological variables in trained cyclists." Journal of the International Society of Sports Nutrition 12.Suppl 1 (2015): P20.
• Mumford, Petey, et al. "Effects of sub-chronic branched chain amino acid supplementation on markers of muscle damage and performance variables following 1 week of rigorous weight training." Journal of the International Society of Sports Nutrition 12.Suppl 1 (2015): P29.
• Sanders, Gabriel J., et al. "The effect of three different energy drinks on oxygen consumption and perceived exertion during treadmill exercise." Journal of the International Society of Sports Nutrition 12.Suppl 1 (2015): P1.
• Sharp, Matthew, et al. "The effects of beef protein isolate and whey protein isolate supplementation on lean mass and strength in resistance trained individuals-a double blind, placebo controlled study." Journal of the International Society of Sports Nutrition 12.Suppl 1 (2015): P11.
• Van Eck, Leighsa E., et al. "Effect of post-exercise ingestion of different molecular weight carbohydrate solutions. Part III: Power output during a subsequent resistance training bout." Journal of the International Society of Sports Nutrition 12.Suppl 1 (2015): P32.
• Wilder, Nathan, et al. "The effects of low-dose creatine supplementation versus creatine loading in collegiate football players." Journal of athletic training 36.2 (2001): 124.

Older Human Study Shows: 2.72g Carnitine per Day Ward Off Fat Gains - Specifically on the Trunk | User Question: Are We Missing Out If We Are Not Using Carnitine?

SuppVersity reader Derek D. wants to know if 2013 study shows we are missing out if we don't use carnitine.

When I answered your questions on Facebook, the other day, Derek D.'s question about the results of a 2013 study by Stephens et al. stood out, because Keller's study suggest that carnitine may be significantly more useful while bulking than it is during a cut (which is still what it is marketed for).

If you are a long-term SuppVersity reader, you will be aware that this is not the first SuppVersity article discussing a study that points to the use of carnitine outside of dieting scenarios. In 2013, for example, I wrote about a study by Keller et al. (2013). A study that found significant increases in pro-anabolic hormones and proteins, and a 7% improvement in lean-to-total-mass ratio in rodents in response to a relatively low amount of carnitine in the diet.

You can learn more about carnitine at the SuppVersity!

Carnitine for Acute Endurance Perf. Boosts

Carnitine too Low in Many Vegetarians

Carnitine? Which Type Should You Use?

Carnitine as a Body Recomp Agent?

Choline, Carnitine, Caffeine = Fat Loss Booster

Will Carnitine Increase Your Cancer Risk?

Now, what's interesting about the study Derek asked about is that it was done in human. In only 12 healthy (the scientists planned for 16 which is not much better, but there were 4 drop-outs), non-vegetarian, male recreational athletes ("non-vegetarian" is important because vegetarians and vegans may benefit much more from carnitine supplements | learn more), to be specific. It's also noteworthy that Stephens et al. used dual-energy X-ray absorptiometry (DEXA) to assess the body composition of the subjects and incorporated a complex array of gene essays to assess what could drive the changes the UK researchers observed in response to the ingestion of a beverage containing 1.36 g of L-carnitine and 80 g of carbohydrate twice a day.

Figure 1: The changes look to good to be true and may in fact be purely random (Stephens. 2013).

In that, the high GI (Vitargo(R)) carbohydrate source was added mostly to stimulate insulin-mediated muscle carnitine transport (adding CHO + choline would have been even more effective | learn more) and not to fatten the who consumed their two orange-flavoured beverages in the morning and 4h later (without foods!) for 12 weeks up.

It may thus have been a bit surprising for the researchers, when they realized that the subjects in the control group gained a significant amount of (trunk) fat over the 12-week study period - a pro-obesogenic effect that was prevented by the additional 2.72 g/day of carnitine which also increased the total energy expenditure (significantly) and the fatty acid oxidation (non-signifcantly) over Control.

The more choline the better the carnitine retention; and the better the retention the less high carnitine red mead you'll have to eat... just kiddin'. Irrespective of whether you do or don't eat red meat. Choline supplements are a much better way to increase carnitine retention than tons of carbs | learn more.

So, carnitine keeps you lean on a bulk? In view of the fact that there was neither a dietary nor an exercise control in place, the results of a small scale study like this has no value whatsoever. I don't care about the observed increases in muscle total carnitine, long-chain acyl-CoA and whole-body energy expenditure. I don't care about the seventy-three of 187 genes relating to fuel metabolism that were upregulated in Carnitine vs. Control after 12 weeks. And I don't care about the fact that some of these genes were involved in 'insulin signalling’, ‘peroxisome proliferator-activated receptor signalling’ (PPARs are involved in fatty acid metabolism), either.

What I do care about is that a study without rigid dietary and exercise control with only 6 subjects in each of the two groups can produce outstanding results that are nothing but random and that's why the study at hand doesn't provide the evidence that would be necessary to answer the question in the headline, i.e. "Are we missing out if we don't use carnitine?", affirmatively | Comment on Facebook!

References:

• Keller J, Couturie A, Haferkamp M, Most E, Eder K. Supplementation of carnitine leads to an activation of the IGF-1/PI3K/Akt signalling pathway and down regulates the E3 ligase MuRF1 in skeletal muscle of rats. Nutrition & Metabolism. 2013; 10:28. 
• Stephens, Francis B., et al. "Skeletal muscle carnitine loading increases energy expenditure, modulates fuel metabolism gene networks and prevents body fat accumulation in humans." The Journal of physiology 591.18 (2013): 4655-4666.

Carnitine Loading Revisited: 3g Carnitine per Day Ward Off Vitargo Induced Fat Gain by Increasing Fatty Acid Oxidation and Total Energy Expenditure in 12 Week Human Study

Figure 1: With highly bioavailable carnitine in meat it is 100% paleo (unlike coke, obviously ;-)

I am not sure, whether its ten, twenty or maybe two-hundred ;-) years ago that the first carnitine supplement was introduced to the sport supplement market (from a paleo perspective it has always been there - in the form of meat!); and honestly I am too lazy to google it up. What I do know, however is that carnitine has been around ever since I first started working out. Incidentally, the same can be said about the debate whether or not supplementing with one or another form of this endogenously synthesized amino acid (your body can make carnitine from the amino acids lysine and methionine) would actually or just theoretically be beneficial for the average trainee.

Years have passed and I still hesitate, whenever someone asks me whether or not I'd recommend trying this or that form of l-carnitine to increase his or her performance. After years of being inclined to answer: "Very unlikely." The publication of a handful of promising studies over the past months makes me question, whether "May be worth a try" would not be a more appropriate response to this sixty-four-thousand dollar question.

Sixty-four-thousand dollars for l-carnitine?

The most recent of these studies is going to be published in the Journal of Physiology in a couple of weeks. It was conducted by researchers from the MRC/Arthritis Research UK Centre for Musculoskeletal Ageing Research, School of Biomedical Sciences at the University of Nottingham in the UK, and investigated the effects the provision of 2x1.36g of carnitine per day had on the energy
metabolism, body fat mass, and muscle expression of fuel metabolism genes.responses of 12 men who exercised at 50% VO2max for 30 min once before and once after 12 weeks twice daily feeding of

• 80 g carbohydrate from Vitargo (Control, n=6) or 
• 1.36 g L-carnitine + 80 g carbohydrate (Carnitine, n=6). Maximal

Contrary to what you may expect, the activity of the "fatty acid carnitine shuttle" or rather the corresponding mitochondrial enzyme, namely carnitine palmitolytransferase 1 (CPT1) remained similar in both groups over the course of the 12-week study period.

Suggested read: "Meaty "News": Choline, Carnitine & "Bacteria Poop" Make (Red) Meat Unhealthy. Learn Why the Latest Revelations Are Neither New, Nor Meat-Specific And Still Made the News" (read more)

Still, the additional carnitine did prevent the statistically significant weight and fat gain (1.9kg and 1.8kg, respectively) the scientists observed in the the control group. It also ...

• increased the muscle total carnitine concentration by +20%
• ramped up the activity of long-chain acyl-CoA, an enzyme that is crucially involved in the mitochondrial oxidation of long-chain fatty acids by +200% and
• upped the whole body energy expenditure by a comparatively small, but statistically significant +5%

Moroever, the researchers found 73 out of 187 genes relating to fuel metabolism to be upregulated in the subjects who had been randomized to the active arm of the study.

What mechanisms are at work and what do they do?

Now it is unquestionably not straight forward how these results relate to the one and only practically relevant outcome of the study - the lack of weight gain. Therefore it does appear prudent to take a look at what the researchers say about the relationship between the total carnitine levels, the expression of long-chain acyl-coa and the overall increase in energy expenditure on the decreased weight gain.

Their reasoning that the"20% increase in muscle carnitine content prevented the 1.8 kg increase in body fat mass associated with daily ingestion of a high carbohydrate beverage." Does yet not have large explanatory power imho. If the participants had been following a regular workout routine and the whole body energy expenditure hat been increased in all of these sessions to the same degree it was in the post-intervention test (+5%), this would probably make sense.

Table 1: Amount of carnitine in selected foods (learn more)

If we take a look at the other parameters the scientists measured, it is likely, yet by no means dead certain that this increase took place. After all, the changes in energy expenditure  were accompanied by...

"[...] an increase in fat oxidation, and a marked adaptive increase in the expression of gene networks involved in insulin signalling, peroxisome proliferator activated receptor (PPAR) signalling, and fatty acid metabolism over and above the decline observed in Control." (Stephens. 2013)

If we do assume that exercise does not thwart (maybe even promote) these effects, it could thus in fact make sense to answer the sixty-four-thousand dollar question by stating that it may at least be worth a try for those with unlimited funds.

And that despite the fact that the "mechanism underlying the increase in energy expenditure is not entirely clear" (Stephens, 2013) and the researchers can only speculate that it may be the result of carnitine driven increases in the rate of fac oxidation.

"Muscle free carnitine content was not measured after 20 min of exercise in the present study, but in our previous study (Wall. 2011) a 20% increase in skeletal muscle total carnitine content following 24 weeks of daily L-carnitine and carbohydrate feeding resulted in a striking 80% greater availability of muscle free carnitine following 30 min of low intensity exercise compared to Control, which was associated with a 30% reduction in PDC [pyruvate dehydrogenase complex] activation and 55% reduction in muscle glycogen utilisation." (Stephens. 2013)

For these changes to become practically relevant they would yet, as Stephens et al, suggest have to be present at reast, And while the 4-fold increase in resting muscle long-chain acyl-CoA content, of which the authors have shown previously (Stephens. 2006) to be consistent with an increase in muscle carnitine content and a switch in fuel metabolism at rest, would suggest that this is the case, I am not yet inclined to back off of my "probably not worth the extra bucks".

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Carnitine may also ramp up anabolic and shut down catabolic signals in trainees and I'd say this is probably a better argument to supplement than the "anti-cok(e)obesity effect" (learn more)

Bottom line: Despite the accumulating evidence of real world benefits of carnitine supplementation it would be cheaper and way easier to simply not guzzle an additional 4x servings of coke a day if you want to avoid weight gain.

And if you are really looking for arguments in favor of carnitine supplementation I'd suggest you'd rather base your decision to invest into a bag of bulk l-carnitine on the IGF-1, p-AKT and mTOR boosting and and atrogin, murf and fox-o inhibiting anabolic and anti-catabolic effects study by Keller et al. reported in their March 2013 study you've read about here at the SuppVersity on March 18, 2013 (read more).

References:

• Keller J, Couturie A, Haferkamp M, Most E, Eder K. Supplementation of carnitine leads to an activation of the IGF-1/PI3K/Akt signalling pathway and down regulates the E3 ligase MuRF1 in skeletal muscle of rats. Nutrition & Metabolism. 2013; 10:28 
• Stephens FB, Wall BT, Marimuthu K, Shannon CE, Constantin-Teodosiu D, Macdonald IA, Greenhaff PL. Skeletal muscle carnitine loading increases energy expenditure, modulates fuel metabolism gene networks, and prevents body fat accumulation in humans. J Physiol. 2013 Jul 1. [Epub ahead of print]
• Wall BT, Stephens FB, Constantin-Teodosiu D, Marimuthu K, Macdonald IA, Greenhaff PL.
  Chronic oral ingestion of L-carnitine and carbohydrate increases muscle carnitine content and alters muscle fuel metabolism during exercise in humans. J Physiol 2011. 589:963-973.