To Spit or to Swallow - That is the Question! Carbohydrate Mouthrinse May Be Better Than Water, Yet Still Not an Option for Performance Oriented Athletes

Image 1: "You need carbs to fuel your workouts!" You know the whole litany... what may be news to you is that scientists are speculating that "intra workout carbs" do not necessarily have to be ingested to do their ergogenic magic.

Those of you, who already "friended" me on Facebook and are following what is going on on the SuppVersity Facebook page (just want to remind you that Facebook has now an option that allows you to be informed, whenever something new is posted), will probably remember the discussion revolving around "carbohydrate mouthrinsing" and whether or not it may be even more beneficial to spit and not to drink your Gatorade... now, all the health benefits of low-carbohydrate (when I am talking "low" I am not talking of Atkins type <80g) diets aside, it does seem pretty counter-intuitive that just swishing one of those carbohydrate-laden electrolyte drinks in between your teeth for a few seconds, to then spit it out again could actually have any merit. Yet, science, or I should say a handful of studies, do suggest otherwise.

As part of their recently published study into the effects of carbohydrate mouthrinsing on exercise capacity in the pre- and postprandial state (Fares. 2011), Elie-J. M. Fares and Bengt Kayser have compiled a list of the 8 hitherto published peer-reviewed papers on that subject. And if you just went by the column "increased perfomance", "yes or no", it appears like it was an established fact that carbohydrate mouthrinsing was highly ergogenic. After all, six out of the eight studies are marked with the tag "increased performance".

Figure 1: Performance increases and standard deviations of the respective measures from studies on the advantage of carbohydrate vs. artificially sweetened or plain water mouthrinse (data calculated based on summary in table 2 of (Fares. 2011)

If we do yet have a look at the quantity of those performance increases and the individual standard deviations (I compiled the respective data for you in figure 1), things begin to look less conclusive. I mean, there is obviously a standard deviation for both arms of each study and there also is a mean improvement (or decrease in performance), but if the "performance increment" is smaller than the standard deviation, for all but one study, this does make me feel uncomfortable with the statement that I would see "scientific evidence", let alone "conclusive scientific evidence" in support of carbohydrate mouth-rinses.

Mouthrinse vs. placebo = minimal (if any advantage), but what about vs. ingestion?

Regardless of what you think about the real world significance of an average performance increase of 1% (calculated based on the data from figure 1), for the small fraction of athletes for whom these minimal performance increases would actually count, i.e. high intensity endurance athletes, like time-trial Tour de France cyclists, the "control", or I should say the "benchmark" should not be plain or sweetened water, but rather one of these crab-, ah... pardon me, carb-loaden sugary electrolyte drinks these athletes are habitually consuming. I was thusly happy to see that Catherine Moss, a student of Sports and Exercise Sciences at the Massey University in Auckland, New Zealand has recently conducted an experiment for her thesis that has much more practical relevance for the high achieving athletes (Moss. 2011).

Table 1: Composition of the placebo and CHO supplement in the Moss study (adopted from Moss. 2011)

In a randomized, counter-balanced, double-blind study, Moss had eight recreationally trained cyclists perform a time trial (with a predetermined amount of work) in the course of which the cyclists ingested or rinsed (swirling 0.33ml/kg body weight of the solution for 8s) with either a placebo solution or a carbohydrate drink, whenever another 12.5% of the total work was done. In that it is worth mentioning that the composition of the CHO solutions differed for the one that was meant to be ingested and the one that was intended to be swished. With the former containing 7.5% and the latter 15% carbs, Moss mimicked solutions that had been used "successfully" previous studies. I do yet no idea, why the placebo did not contain electrolytes, as this could obviously have made a difference at least in the ingestion trials... I guess this is what distinguishes a thesis like this from a study that is worth being published in a peer-reviewed journal ;-)

Figure 2: Mean power output (in Watts) at different time points during time trial (data adapted from Moss. 2011).

As the performance data in figure 2 goes to show, only the ingestion of the carbohydrate led to significant improvements in mean power output, specifically at the later stages of the time trial. This "breakdown" may be explained by the "glycogen reduction exercise protocol" all participants had conducted the day before the time trial. So that after a "low carbohydrate" dinner, the participants were supposed to be glycogen depleted when they performed the time-trial on the subsequent morning.

Figure 3: Total time (in s) during time trial (data adapted from Moss. 2011).

In a way this is an unfair advantage, for the carb ingestion, which accordingly elicited way better time trial times. It does yet not lessen the significance of data on carbohydrate vs. water mouth rinse, which shows pretty conclusively that in a glycogen depleted state both forms of mouthrinsing (plain water or a 15% carbohydrate solution) are equally ineffective, when it comes to actual performance increases.

Figure 4: Pleasure / displeasure feeling during time trial (data adapted from Moss. 2011).

If you do however look at the pleasure/displeasure feeling scale data in figure 4, I would speculate that in a non-glycogen depleted state the carbohydrate-rinsers would have performed significantly better... I mean, without gas in the tank a car won't work even if it "wanted". In view of the fact that the carbohydrate ingestion group did yet pedal at a higher intensity, this would warrant further investigation.

Figure 5: Respiratory exchange ratio (higher values = higher carbohydrate oxidation) during time trial (data adapted from Moss. 2011).

That being said, there was what I consider an interesting effect of carbohydrate rinsing on the respiratory exchange ratio (remember higher values = higher carb oxidation), which would suggest that the theory Fares and Kayser propose (Fares. 2011), according to which the activation of sweetness taste receptors cells (T1R2 and T1R3) in the mouth would explain the previously cited performance "increases" in other studies, may have its merits. What else than the sensation of incoming carbs could explain that the cyclists burned more carbs in the carb mouthrinse compared to the placebo mouthrinse trial (cf. figure 5) - and that in the absence of significant differences in blood glucose or insulin levels?

Spit it or suck it? What's right for you?

While we do not know whether it would make sense to mouthrinse in a glycogen repleted state (yeah, I know +1% ;-), for any athlete interested in maximal performance, simply ingesting his carb + electrolyte drink would certainly be the best option. The (intermittendly) fasting dieter, who wants to maximize his fatty acid oxidation in the course of say his "morning cardio", on the other hand, would be best off with a non-carby electrolyte drink that helps him avoid dehydration and does not compromise (even if the effect is minimal) fatty acid oxidation... what? You want to know who would  benefit from spitting his carbs out? Well, at least based on the current data, mostly the cleaning contractors of your local gym - after all, they would have to work overtime (and be paid overtime) to clean up the mess ;-)

Fructose Impairs Fatty Acid Oxidation: Replacing 26g of Starch and Lactose in low GI Meal by Fructose Decreases Postprandial and Exercise Fatty Acid Oxidation by -21%

Image 1: With just bacon and eggs for breakfast you would not run the "risk" of reducing fatty acid oxidation.

A carby meal, i.e. a meal with a high amount of carbohydrates, right before workout triggers a shift in substrate utilization, i.e. the type of energy resource, your body will use to fuel the subsequent workout, from fats to carbohydrates, right!? But does it make difference whether you eat a Snickers bar or drink a can of Coca Cola, if both contained the same amount of carbs? Or, in other words, does the source and/or the glycemic index of your pre-workout meal have an impact on the respiratory quotient (RQ), which is the quotient of the amount of exhaled CO2 and inhaled oxygen, with higher RQs (towards 1.0) indicating that you are predominantly running on carbs, and low RQs (towards 0.7) indicating that you derive a greater part (not all!) of your energy from fatty acids.

Orange juice with breakfast? Better not...

The question, whether GI and carbohydrate type of a meal would have a significant impact on the postprandial glucose, lactate and free fatty acids levels, as well as the insulin response and the subsequent carbohydrate and fatty acid oxidation in the course of a low intensity 1h walk, has been bothering Feng-Hua Sun and his (or her?) colleagues from the Department of Sports Science and Physical Education at the Chinese University of Hong Kong, too. In a counter-balanced crossover design (>=7 days between trials; identical, recorded diet in the 3 days before each trial), all 10 healthy male subjects reported fasted (10-12h) at the laboratory, where they consumed one out of three meals with identical macronutrient composition, yet varying carbohydrate sources and glycemic indexes (cf. figure 1).

Figure 1: Macronutrient (in g) and ingredient composition of
the three test meals (according to Sun. 2011)

As you can see, the meals have identical caloric values and macronutrient compositions. Unfortunately, the differences between the ingredients go beyond their plain sugar vs. starch vs. fructose content. After all, spaghettis are not rice and milk is not ham ... this is a design flaw, of which I think that it impairs the significance of the results, but hey! At least the Chines have grasped the idea that calorie is not a calorie...

After all participants had finished eating their "delicious" breakfast, they remained seated for another 120min, in the course of which they had to drink 2ml of water per kg of body weight every 30 minutes "to ensure adequate hydration and balance the water content of the meals".

After these sedentary 2 hours, the subjects performed a standardized 5 min warm-up at 40%  of their individual VO2 and then completed 60 min of brisk walking at 50% of their VO2max.

Figure 2: Differential postprandial (2 hours) glucose (left) and insulin (right) response to the three test meals
(data adapted from Sun. 2011)

As you can see in figure 2, there were significant difference in the postprandial (120 min before exercise) glucose and insulin response to the different meals. Yet, while the difference between the low and high GI meals was something you should have expected, judged by the GI, the fructose enriched LGF meal should not have produced greater glucose (+63% area under the curve, cf. figure 2, left, small graph) and insulin (+62% area under the curve, cf. figure 2 right, small graph) responses than the low GI, no fructose meal, which, in fact, had a slightly lower glycemic index.

Figure 3: Postprandial (2 hours) lactate concentration in the 10 subjects after ingestion of the three test meals
(data adapted from Sun. 2011)

What is yet even more striking is the profound increase in lactate concentration during the prostprandial (not the exercise phase) in the subjects who consumed the fructose-containing meal (cf. figure 3). With +211% (lactate AUC) the postprandial lactate concentration in the LGF group is more than 3x higher than in the LG group! A clearcut sign for an increase in hepatic glycolysis and probably part of the reason that we are seeing increased carbohydrate and decreased fatty acid oxidation rates in the course of the subsequent walking exercise (cf. figure 4).

Figure 4: Postprandial, during exercise and total substrate utilization (in g) subsequent to the ingestion of the three different test meals (data adapted from Sun. 2011)

Postprandially, the increase in carbohydrate oxidation is even more pronounced in the LGF group than in the HG (sugar) group. That being said, the total reductions in fatty acid oxidation are -21% for the low GI fructose (LGI) and -23% for the high GI sugar (HG) group and thusly, within their respective statistical margins, identical!

With respect to the underlying reasons of this disadvantageous shifts in substrate utilization, Sun et al. speculate, that the mechanism

[...] behind this may be the reduced hyperglycemia and hyperinsulinaemia during the postprandial period following LGI meal consumption. [...] In addition, it is well known that insulin can suppress the lipolysis. This suppression appears to be long lasting, even when insulin concentration has returned to basal levels.

The last part, here, is of particular interest, because, obviously, after a few minutes of walking and with the increased need for carbohydrates the insulin levels of all subjects (regardless of the composition of their prior meals) dropped to levels ~2-3mU/L. Now the insulin response in the LGF group was still smaller than the one of the high GI (HG) group, so that the scientists assume that the ability of the fructose to bypass first rate-limiting enzymes of glycolosis in the liver, which renders it readily available for oxidation, must explain why the ratio of carbohydrate to fat oxidation was still similarly skewed in both, the low GI, plus fructose, and the high GI groups.

Image 2: I wonder if nutritionists will ever understand that there is difference between fructose powder (left) and an apple (right)

Although these results stand in line with the detrimental effects of fructose sweetened foods, I would still like to see two methodologically flawless studies with a) meal 1 not using different foods (I mentioned that in the 4th paragraph of this post already) and b) fructose from whole fruit and not in the form of the powdered poison Sun et al. just dissolved in water and added to their meals... and you know, in case these studies will be done - sometime in the distant future, when mainstream nutritionists will finally understand that not only is a calorie not a calorie, but that powdered fructose is also not an apple, you will read about that on the SuppVersity, first!

Intra-Workout Supplementation: Increased Carbohydrate Oxidation with L-Arginine, Lower Fat Oxidation with Glucose & Lowest Rate of Perceived Exertion with Plain Water

Image 1: This bird certainly knows about the importance of adequate hydration ;-)

Have you been at the gym today? If so, what kind of beverage have you been sipping in the rest-periods between your sets, your sprints or during your regenerative (not fat burning ;-) "classic" cardio exercise? Was it Funky XYZ the latest and greatest intra-workout product on the market? If so, you better check out its ingredients, who knows maybe the "latest and greatest" turns out to be quite counterproductive towards the goals you have been setting after reading one of the last two installments of the Intermittent Thoughts? Let's assume you are the "Peter Griffin"-type of chubby - in that case, I hope that your Funky XYZ did not contain glucose, maltodextrin, waxy maize, or any other of the sugars of which the supp companies are going to tell you that they "superior" to the white poison your granny uses in her delicious muffins. Why? Well, according to a soon to be published study by scientists from the Massey University in Wellington, New Zealand, as little as 12g of glucose will reduce the amount of endogenous fatty acid (i.e. the stuff your body is using to hide your abs ;-) oxidation by -22%! Sounds terrible, doesn't it? Well, let's look at some details to decide whether those -22% will really make a difference and what effects the presence of l-arginine and l-glutamine in your intra-workout supplement could have had.

150 min @ 177 Watt + Glucose + (Glutamine or L-Arginine) = ???

Figure 1: Composition of the intra-workout supplement; sodium citrate base + 12g glucose (glucose) and additional 1g l-glutamine (Glu + L-Glutamine) or 0.1g l-arginine (Glu + L-arginine)

It stands out of question that adequate hydration is of utmost importance, when it comes to maximizing athletic performance (incidentally, the same is true, when it comes to "burning fat"). What athletes should drink before (pre-hydration), during (hydration) and after your workouts (re-hydration) is thusly one of the classic topics of exercise science and the recent study by D.S. Rowlands et al. is thusly probably #1001 on the never-ending list of investigations into the optimal mineral and nutrient composition of intra-workout drinks. For us, it is of interest, because it is one of the few which investigated the differential effect of the amino acids l-arginine and l-glutamine on substrate utilization, plasma glucose, lactate and sodium levels and rates of perceived exhaustion in eight male cyclists and triathletes during 150min (!) of cycling at 50% of the individually predetermined peak power (this is noteworthy, because 50% of their peak power equalled 177 W, which is not exactly "light" exercise), in the course of which the athletes consume 150ml of a fluid containing a 0.95g sodium base and either 12g of glucose alone or a combination of glucose and either 1g of l-glutamine or 0.1g of l-arginine (cf. figure 1).

Figure 2: Oxygen consumption (L/min) and substrate utilization (g/min) in 8 trained cyclists / triathletes during 150 min of cycling at 177W with 150ml of four different intra-workout drinks (data adapted from Rowlands. 2011)

As a seasoned student of the SuppVersity, it should not surprise you that the exogenous (i.e. from the outside) supply of glucose produced a -22% shift in substrate oxidation from fatty acids to the now more readily available carbohydrates (cf. figure 2). What you have probably not expected, though, is that the addition of the minuscule amount of l-arginine (which is btw. about what you will get with many of the proprietary blends in the still incredibly popular "NO-boosters") would promote this shift by increasing the total amount of oxidized carbohydrates by another ~10% over the 12g glucose solution alone.

Figure 3: Comparison of total / relative substrate utilization for the 12g glucose + 0.1g arginine, the 12g glucose and the water + sodium citrate groups (data adapted from Rowlands. 2011)

Now you are stunned, hah? So after all it is yet not your fault that you cannot see your abs. It's your NO-suppement! Well, not exactly. I mean take a look at the way I arranged the data in figure 3. You will probably acknowledge that the 12g glucose + 0.1g l-arginine group "burned" more energy - if you want it in calories (remember this is stupid ;-) 0.68kcal/min or 102kcal during the whole session and then come back to the -22% reduced fatty acid oxidation and lament: "But Dr. Andro, they burned 22% less fat than the water-only group! Now I know why I don't get lean." If that is your train of thought, I would invite you to continue the idiotic kcal number crunching and calculate on how much fat the poor l-arginine group would have missed to burn... well, it's the "exorbitant" amount of 170mg/min or - for the whole session 25.5g! While this may be more than one tablespoon of coconut oil, I guess you will probably admit that this probably is not the reason your abs are still covered by a thick layer of flabby adipose tissue, won't you?

Arginine reduces oxygen cost at the expense of glucose

Now, the real interesting findings of the studies are thusly not the changes in substrate utilization but rather the profound impact the addition of the two amino acids had on the lactate levels during the 150min of cycling (cf. figure 4) and the rates of perceived exertion (RPE).

Figure 4: Plasma lactate levels (mmol/L) in 8 trained cyclists / triathletes during 150 min of cycling at 177W with 150ml of four different intra-workout drinks (data adapted from Rowlands. 2011)

The latter (RPE), and this is actually quite surprising, were minimal in the water + sodium citrate group and maximal in the 12g glucose + 1g l-glutamine group (0.8 pts greater on a 0-7 scale). The RPE values of the arginine group, on the other hand, were only marginally elevated and that despite the significant increase in glucose clearance, which, by the way, has also been observed by McConell et al. (McConell. 2006) and Linden et al. (Linden. 2010). 

In view of recent studies such as Greer et al. (Greer. 2011), who observed a small, but statistically significant decreases in endurance during a strength training circuit in response to Arginine-Alpha-Keto-Glutarate (AAKG) supplementation, it is yet very unlikely that the observed effects of an arginine-enriched glucose containing intra-workout supplement observed in this study "have the potential to benefit endurance exercise performance" (which is what the scientists, much to my surprise, conclude). Another thing is yet more than likely, I would even say it is 100% certain: Neither the results of this nor of any future study will change the sales ranks on Bodybuilding.com & Co., where the purported NO-Boosters (and factual stimulants) still are the front-runners of the "TOP 10 selling products" ;-)

Carbohydrate Supplementation During Workouts - Who Benefits? How Much and Which Type(s) of CHO are Best?

Compared to liquid beverages, gels have the advantage of causing lower GI stress, when significant quantities of CHOs are consumed during exercise. Bars, can be held in the cheek pouch and chewed during critical phases of a race.

The headline gives it away. Today's SuppVersity article is a brief review of the (mostly sponsored) literature on Gatora.... ah, I mean carbohydrate supplementation during exercise. The headline also implies that the usefulness and efficacy of carbohydrate supplements depends on exercise duration and the type of exercise.

As a seasoned student of the SuppVersity you will know that certain paradox involved with regard to the duration / type of exercise. Short exercise durations, for example, shouldn't require large CHO boluses, long duration exercise, on the other hand, is fueled mostly by fat - so why should you supplement with carbohydrates, anyway?

Want to improve your exercise performance? Try sodium bicarbonate, as well!

The Hazards of Acidosis

Build Bigger Legs W/ Bicarbonate

HIIT it Hard W/ NaCHO3

BA + Bicarb are Synergists

Bicarb Buffers Creatine

Creatine + Baking Soda = 2x Win!

I promise to answer this and other questions in the following paragraphs, but before I do so, I would like to point out that there is as of now no evidence that the much-praised "fat adaptation" increases the exercise performance to an "Olympia" level. Carbohydrate supplements, on the other hand, are still part of the regular supplementation regimen for the 99% of the top athletes.

That being said, the human physiology dictates that the use of carbohydrate supplements during aerobic workouts that last less than 60 minutes is useless, because muscle glycogen is generally not limiting to performance when exercise durations are less than ~60 minutes.

It should not work for short duration exercise, but it still does

Interestingly, 16 out of 23 studies, Trent Stellingwerff and Gregory R. Cox from the Canadian Sport Institute-Pacific and the Australian Institute of Sport reviewed for their recent paper in Applied Physiology have found that carbohydrate supplementation and/or oral (mouth) exposure to carbohydrate can improve performance of tasks less than 1 hour in duration:

You won't fully deplete your muscular glyocogen levels
during short duration resistance training (Haff. 2003)

"In 2004 a seminal paper was published showing that a carbohydrate mouth-wash (swirling 25ml of a 6% CHO beverage (only ~1.5g of CHO in 25ml [6.4% maltodextrin solution (CHO)]) around in the mouth for ~10 sec, every 7.5min) significantly improved time trial (TT) performance [in seven male and two female endurance cyclists] by ~3% (Carter et al. 2004a)." (Stellingwerff & Cox. 2014)

This effect of CHO mouth-washing to improve performance in events from 30-60min has now been replicated in several other performance studies (10 of 13 studies) using both cycling and running interventions and with both sweet (sucrose) and non-sweet (maltodextrin) caloric CHO sources,as compared to 5 non-caloric artificial sweetener placebo trials showing no performance enhancing effects.

Figure 1: Hard to believe, but true - In 2010 Pottier et al. observed that CHO mouth-rinsing, but not CHO ingestion increases the 1h high intensity time-trial performance in trained subjects.

 "All these findings have been mechanistically supported with a functional magnetic resonance brain imaging study showing that CHO mouth-washing from both sweet tasting glucose and non-sweet maltodextrin can stimulate the brain areas of the insula/frontal operculum, orbitofrontal cortex and striatum, which are involved with brain centers responsible for reward and motor control (Chambers et al. 2009). Interestingly, if the mouth (oral receptors) and GI tract is by-passed by CHO infusion straight into the blood stream then 1h cycling TT performance was unaltered as compared to no CHO supplementation (Carter et al. 2004b)." (Stellingwerff & Cox. 2014)

Studies evaluating the effects on perceived exertion (Fares et al. 2011) found similar benefits all of which support the idea that the effect does not occur in the musculature, but rather in the head.

So what do you do to benefit during short-duration (<60) minute workouts? To benefit during short duration exercise exercise (<1h) ~1.5g of high GI carbohydrates (30g/h total = max) consumed or used as a mouth-wash in servings of 25ml for 5 to 10 sec every 8 to 10 min of exercise will do the trick. Since it can be difficult to actually drink / mouth-wash with CHO during critical phases of the race, Stellingwerff and Cox suggest "placing a sports confectionary in the cheek cavity" as a more practical option for some athletes.

It should be obvious that the physiological, or rater intra-muscular benefits of carbohydrate supplements increases with the exercise duration.

CHO supplementation during exercise that lasts 60 minutes or longer

In view of the fact that it is 100% logical and well established by studies by Coyle et al. (Coyle 1992a; Coyle 1992b) that the intake of carbohydrate (glucose alone, and glucose + fructose blends) can significantly improve prolonged endurance capacity and performance (>60min of exercise (Jeukendrup 2010)).

Figure 2: Overview of the performance increases in the 50 studies Stellingwerff & Cox reviewed (2014)

Against that background I will not bother you with another overview of the results, but focus on the efficacy of different carbohydrate supplementation strategies and types of carbohydrate supplements for exercise durations beyond the "magical" hour.

Glucose + fructose - the combination advantage

As a SuppVersity reader you've previously heard about the benefits of combining glucose and fructose in your intra-workout beverage. It is thus only logical that most commercially available formulas are mixtures  glucose + fructose (GLU:FRU) or maltodextrin + fructose - so-called "multi-transportable CHOs". The advantage of using both glucose and fructose is that the carbohydrates will be absorbed via SGLT1 and GLUT5 intestinal transporters.

Comparison of single vs. mutliple CHO sources (CHO, carbohydrate; FRU, fruc- tose; GLU, glucose; Perf, performance; P, placebo; TT, time-trial; TTE, time to exhaustion; Signif, Significant; SUC, sucrose; Stellingwerff & Cox. 2014)

Fructose + glucose mixtures excel, but it takes carbohydrate intake rates of more than 60g/h for the advantages to reach statistical significance. Why? Well, less than 60g/h don't overload the regular glucose transporters in the gut, and the advantage of having both SHLT1 and GLUT5 intestinal transport becomes irrelevant. Several studies have now shown that high intake rates (>70g/h) of GLU:FRU blendsduring moderate intensity, prolonged (>2h) exercise, results in ~8% improvement in endurance performance over both a  1h  TT  (Currell  and  Jeukendrup  2008)  and  over  100km  of  cycling  (Triplett,  Doyle  et  al.  2010) compared to glucose alone, and 19.5% versus water (see Table 1). Another research group has shown  further increases in performance with GLU:FRU blends over multiple sprints  after an endurance pre-load (O'Brien and Rowlands 2011; O'Brien, Stannard et al. 2013).

Specifically during long(er) duration exercise, when the carbohydrate consumption can exceed 60g/h there is a significant performance increase with multi- vs. single source carbohydrate supplements (Stellingwerff & Cox. 2014)

An advantage that has been scientifically established among others by Jeukendrup et al. (2010) who found that this pattern of CHO ingestion results in ~20 to 50% higher CHO oxidation rates compared to the ingestion of a drink that contains nothing but glucose or maltodextrin.


Now an increase in carbohydrate oxidation alone does not sound like something you would aim for as an endurance athlete. In practice, increases in carbohydrate oxidation have yet been shown to increase the performance during prolonged exercise bouts compared to isocaloric glucose-only beverages. (Currell et al. 2008; Triplett et al. 2010; O'Brien et al. 2011; O'Brien et al. 2013).

So how much does it take during long(er) 1-2h+ exercise: You've already learned that glucose + fructose mixtures should be preferred to carbohydrate supplements with only one type of CHO. While 30-60g/h, which is the amount of carbohydrates that is currently suggested by the American College of Sport Medicine (ACSM 2000; Sawka, Burke et al. 2007) appears to be be enough for exercise durations ranging from 60-120 minutes, recent evidence suggests that hard exercise bouts which last longer than 2h require up tp 90g/h or carbohydrate solutions with a CHO content of >8%.

Needless to say that there is still research to be done with respect to individual influencing variables of carbohydrate requirements. The currently available evidence, for example, is largely based on results from runners and cyclists. Two other factors / issues that come to mind are...

• the dose-response relationship, which appears to be capped at 75g/h - at least according to a large-scale multi-center study by Smith et al. (Smith. 2013) who found that their subjects, endurance trained cyclists or triathletes experienced significant performance increases, with increasing amounts of carbohydrates (0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110 and 120g of CHO/h) during a 2h constant load ride.
  
  

  

  Figure 3: Mean log time to complete time trial (natural) as function of CHO treatment condition with fitted quadratic curve (with 95% CI of mean curves). Differences 100 represent percent change in performance. The quadratic function relating CHO ingestion rate to time complete time trial for 43% (95% CI = 11%–75%,P= 0.059) of the variation in mean performance score (Smith. 2013)

  The CHO given was a 1:1:1 glucose:maltodextrin:fructose blend. Results indicated incremental performance improvements of 1.0%, 2.0%, 3.0%, 4.0%, and 4.7% at 9, 19, 31, 48, and 78g CHO/h, respectively, with diminishing performance enhancement seen at CHO levels >78g/h.
  
  The optimal amount for performance (+4.7%) was 78g/h, with a range of 68 to 88g/h. However, even at 10g/h, a 1.0% increase in performance was observed, showing even a small amount of carbohydrate has the potential to positively impact performance. 
• the optimal mix of glucose, dextrose, fructose, maltodextrin or other "special" carbohydrates  - needless to say that waxy maize, hydroxypropyl distarches (learn more) or the expensive fast absorbing highly insulinogenic patented carbohydrate source Vitargo come to mind, when we are talking about finding the optimal mix of different carbohydrate sources - a mix, by the way, of which you can safely assume that it will differ according to the physiological demands of the workout and the exercise duration.
  
  One thing we shouldn't forget, though, is that next to optimal performance, optimal GI tolerance, i.e. the absence of bloating, diarrhea & co would be an important criteria the "optimal" carbohydrate blend would have to meet.

• 

  Figure 4: CHO suppl. ameliorates  testosterone reductions in 800m runners (de Sousa. 2010)

  the impact of carbohydrate supplementation on hormonal changes during and in response exercise - several human studies suggest that CHO supplementation attenuates the suppression of the hypothalamic-pituitary-gonadal axis and the rise in stress hormones during periods of intense training; a recent rodent study shows that the provision of carbohydrate supple- ments can prevent / reverse exercise-associated menstrual dysfunction (de Sousa. 2010; Zhao. 2014)

I guess, I could come up with additional research gabs, but in the end, a list of "gaps" is not exactly useful for you. Much in contrast to a conclusion, which I am about to formulate in the bottom line, now.

Bottom line: As of now it looks as if the recommendations I made in the light(er) blue boxes for short (<1h), long (1-2h) and ultra-long (>2g) workouts are the best we have.

For the majority of resistance trainees, intra-workout carbohydrate supplementation is at best facilitative. The repletion of the depleted glycogen stores after your workouts, however, is necessary | learn more about glycogen repletion

What I find particularly interesting is that for shorter duration exercise situations (<1h) and high(er) exercise intensity, similar benefits can be achieved with swallowing vs.  outh-washing with only 30g/h of liquid CHO sources. Performance increases in the 2.6% ± 3.3% range may not sound earth-shattering, but if you were running for an hour, your competitor who made sure to bring a carb bottle would be 83s faster than you are - that's 83s which could make the difference between first and last place.

For longer duration exercise, the studies, Stellingwerff and Cox reviewed in the previously cited article yielded an intermediate improvement of 4.9%±4.9% with significantly higher values in studies investigation long(er) + higher intensity exercise. The notion that carbohydrate supplements were useless and the various position statements of sporting bodies all over the world just a concession to the sponsoring money of the industry is thus unwarranted | Comment on Facebook!

References:

• Carter,  J.,  Jeukendrup,  A.E.,  Mundel,  T.,  and  Jones,  D.A.  (2003).  Carbohydrate  supplementation  improves moderate and high-intensity exercise in the heat. Pflügers Archiv : European journal of physiology446: 211-9.
• Carter, J.M., Jeukendrup, A.E., and Jones, D.A. (2004a). The effect of carbohydrate mouth rinse on 1-h cycle time trial performance. Medicine and science in sports and exercise36: 2107-11.
• Carter, J.M., Jeukendrup, A.E.,  Mann, C.H., and  Jones, D.A. (2004b). The effect of glucose infusion on glucose kinetics during a 1-h time trial. Medicine and science in sports and exercise36: 1543-50. 
• Chambers,  E.S.,  Bridge,  M.W.,  and  Jones,  D.A.  (2009). Carbohydrate  sensing  in  the  human  mouth:  effects  on exercise performance and brain activity. The Journal of physiology587: 1779-94. 
• de Sousa, Maysa Vieira, et al. (2010). Effects of carbohydrate supplementation on competitive runners undergoing overload training followed by a session of intermittent exercise." European journal of applied physiology 109.3: 507-516.
• Fares, E.J. and Kayser, B. (2011). Carbohydrate mouthrinse effects on exercise capacity in pre- and postprandial States. J Nutr Metab2011: 385962.   
• Pottier, Andries, et al. (2010). Mouth rinse but not ingestion of a carbohydrate solution improves 1‐h cycle time trial performance" Scandinavian journal of medicine & science in sports 20.1: 105-111.
• Sawka,  M.N.,  Burke,  L.M.,  Eichner,  E.R.,  Maughan,  R.J.,  Montain,  S.J.,  and  Stachenfeld,  N.S. (2007).  American College of Sports Medicine position stand. Exerciseand fluid replacement. Medicine and science in sports and exercise39: 377-90.
• Smith, JohnEric W., et al. (2013). Curvilinear dose-response relationship of carbohydrate (0-120 g/h) and performance." Med Sci Sports Exerc 45.2: 336-341. 
• Stellingwerff, T., & Cox, G. R. (2014). Systematic Review: Carbohydrate Supplementation on Exercise Performance or Capacity of Varying Durations. Applied Physiology, Nutrition, and Metabolism (2014). Ahead of Print. 
• Zhao, Can, et al. (2014). Effects of carbohydrate supplements on exercise-induced menstrual dysfunction and ovarian subcellular structural changes in rats." Journal of Sport and Health Science 3.3: 189-195.

Fragmented Sleep Reduces 24h Fat Oxidation by > 50% - Not Getting a Good Night's Sleep Sets You Up For Obesity.

Image 1: It looks awkward, but sleep masks
and ear-plugs are effective, cheap and
save ways to improve sleep quality
(image from lackofsleepsymptoms)

I think you will be familiar with the idea that an insufficient amount of sleep has been found to correlate (! not induce !) with visceral obesity and other negative health markers (e.g. Strian. 2005). Now a study from a the Department of Human Biology, Nutrition and Toxicology Research Institute Maastricht (NUTRIM) at the University of Maastricht in the Netherlands found that not getting a good nights sleep or, in this particular case, waking up every hour, reduces the amount of fat you burn in a period of 24 hours by -52% (Hursel. 2011, cf. figure 1).

Other than in the initially mentioned epidemiological guesswork ... ah pardon, correlation studies, Hursel et al. had their 15 healthy male volunteers report to the laboratory twice (>2 weeks between the sessions of the randomized, single-blind cross-over study). During each visit, the subjects stayed for 48 h in a respiration chamber, where energy expenditure, physical activity (radar), and substrate oxidation were meticulously measured. On both occasions, the subjects had fixed bedtimes (lights out: 11:00pm; lights on: 7:40am) resulting in 8 h sleeping time per night. On one of the occasions, however, the scientists used induced sleep-fragmentation by the means of "approximately hourly wake-up calls" the subjects had to respond to by turning off their alarm after 2 min.

Figure 1: Relative differences in carbohydrate and fat oxidation, as well as respiratory quotient (higher quotient = more carbohydrate dependent) in 15 healthy men as a consequence of interrupted sleep (data calculated based on Hursel. 2011)

Diet-wise, the subjects who had been asked to abstain from strenuous exercise and to sleep for 8 h during the nights before their visit at the lab, were fed a standardized (protein:carbohydrate:fat ratio 12:55:33) diet consisting of "normal, everyday food products" two days before and in the course of their stay in a respiration chamber. The use of the latter, by the way, facilitated pretty exact measurements of the subjects energy expenditure and substrate oxidation (cf. figure 2).

Figure 2: Relative changes in total, resting (REE) and sleeping energy-expenditure (SEE), as well as absolute changes in activity induced energy expenditure (AEE) and overall caloric balance (data calculated based on Hursel. 2011)

As the data in figure 2 shows there was no statistically significant difference with respect to the overall calorie balances of the subjects (+0.41MJ/day to +0.41 MJ/day in the normal vs. the interrupted sleep group, respectively). While this appears counterintuitive as the recorded physical activity of the sleep-disturbed subjects had eventually increased, Hursel et al. point out that because of their study design, ...

we showed an initial increase in physical activity and AEE as an effect of sleep fragmentation, mainly because the subjects had to turn off their alarm clock 7 times during the night. However, the resulting increased exhaustion and sleepiness during the subsequent day might eventually counter-balance physical activity and AEE.

They go on to point out that the increased activity goes hand in hand with the increase in carbohydrate oxidation, the depletion of glycogen stores and the (this is my assumption) stress-related -52% decrease in fatty acid oxidation (cf. figure 1).

The real-world results of this unhealthy combination of non-regenerative sleep, daytime exhaustion and sleepiness and the accompanying abstract metabolic shifts are cognitive problems, a lack of motivation (esp. to work out or do any physical work), carb-cravings, snack-attacks & co... In your efforts to (re-)feed a body that is unable to access his well-stocked fat reserves, you end up overcompensate the initially increased energy expenditure, constantly provoking insulin spikes which totally blunt fat oxidation, trigger temporary hyperglycemia (if you are not already diabetic) and induce further snack-attacks. Thus, you are triggering a down-ward spiral that is especially hard to escape from, if your body does not get the chance to reset his insulin and stress levels in the course of a good nights sleep - keep that in mind before you place your cell-phone next to your pillow in order to "keep in touch" with your (facebook-)friends 24/7, as a very recent study published in the journal SLEEP showed that "mobile phone use for calling and for sending text messages after lights out was associated with sleep disturbances independent of covariates and independent of each other" (Munezawa. 2011).

Citrulline as Substrate Switch. Galactose as Workout Fuel, Glycogen Repletion Not Urgent, 2x a Day 6x a Week = Too Much For Your Antioxidant System, Astaxanthin For IgA

Actually it's not the burn during the workout that matters, but I don't have to tell you that, do I? (pic i-am-beast.com)

What do you do with a whole host of interesting exercise-related nutrition news that are piling up in your archive, but are too good to be "burned" as short links with one sentence of text on the SuppVersity Facebook Wall?

Right! You compile all those news into a potpourri, attach the label "SuppVersity News Potpourri" to it and blow them out in a blogpost of their own. A post that covers the whole peri-workout window as well as the short-/long-term effects on exercise on your anti-oxidant and immune system.

Sounds good? Well, then go ahead...

• Immediate post-workout glycogen repletion in endurance athletes probably useless (Carlsohn. 2013) While the hormonal response and the long-term effects of running around with depleted glycogen levels are a totally different animal, the latest research from the University Outpatient Clinic Potsdam in Potsdam, Germany, clearly suggests that the immediate post-run glycogen-repletion with 1.5g/kg body weight of fast acting carbs per hour is useless...
  
  

  

  Do you remember my "Glycogen-free muscle growth" post(s) from 2011?

  ...at least with respect to the 5,000m running performance of the twelve recreational runners (4m/8w; 1.73 ± 0.11 m, 69.1 ± 13.4 kg). who were involved in Carlsohn et al.'s study.
  

  "Running time during 5,000-m time trials did not differ between bTT (1,305 ± 140 s), following CARB (1,276 ± 125 s) or PLA (1,285 ± 124 s, p= .85). There were no differences in RPE (bTT 18.3 ± 0.3, CARB 18.7 ± 0.3, PLA 18.8 ± 0.9; p= .48), bLa/min, PLA 187 ± 3 beats/min; p= .96).

  In view of these results it should actually not necessary to formulate a "bottom line", but alas...
  

  ---

  Bottom line: "[T]he rationale of recommending immediate carbohydrate intake following exhausting exercise to 5,000-m runners might be questioned" (Carlsohn. 2013). Please keep in mind though that not repleting your glycogen stores at all is not an option - the myth that's been partially busted by the study at hand is that you must do that as fast as possible to maintain maximal performance - not that you must do it at all. 

• "High" galactose foods ?

  Honey	3.10g
  Fermented yoghurt	1.30g
  Beets, canned, regular pack, solids and liquids	0.80g
  Celery, raw	0.66g
  Cherries, sweet, raw	0.59g
  Bockwurst, pork, veal, raw	0.48g
  Corn, sweet, yellow, canned, whole kernel, drained solids	0.36g
  Beans, navy, mature seeds, raw	0.34g
  Snacks, pretzels, hard, plain, salted	0.22g
  Spices, curry powder	0.21g
  Spices, mustard seed, yellow	0.20g
  Spices, paprika	0.19g
  Babyfood, fruit, plums with tapioca, without ascorbic acid, strained	0.19g
  Spices, ginger, ground	0.19g
  Spices, basil, dried	0.19g
  Kiwi fruit, (chinese gooseberries), fresh, raw	0.17g
  Cereals, oats, instant, fortified, plain, prepared with water (boiling water added or microwaved)	0.16g
  Cheese, mozzarella, whole milk	0.15g
  Spices, cloves, ground	0.15g
  Cheese, parmesan, grated	0.15g
  Spices, oregano, dried	0.15g
  Fast foods, cheeseburger; single, regular patty, with condiments	0.15g
  Plums, raw	0.14g
  Peas, green (includes baby and lesuer types), canned, drained soilds, unprepared	0.14g
  Cereals, oats, instant, fortified, plain, dry	0.13g
  Fish, fish portions and sticks, frozen, preheated	0.13g
  Figs, dried, uncooked	0.13g
  Babyfood, plums, bananas and rice, strained	0.12g
  Egg, whole, raw, fresh	0.11g
  Avocados, raw, all commercial varieties	0.10g
  Crackers, saltines	0.07g
  Snacks, tortilla chips	0.07g
  Egg, white, raw, fresh	0.07g
  Snacks, tortilla chips, nacho cheese	0.07g
  Peaches, raw	0.06g
  Melons, cantaloupe, raw	0.06g

  Galactose as alternative workout fuel (Duckworth. 2013) - A recent study from the Leeds Metropolitan University in the UK demonstrates that
  

  "ingesting a solution containing galactose before and during exercise can positively affect postexercise satiety and energy balance throughout the day, compared to a more readily available and widely consumed form of carbohydrate" (Duckworth. 2013)

  The scientists conclude that based on the observations they made, when they provided nine recreationally active eumenorrheic females (mean age 22y; weight 63.3kg) with either 45g galactose (GI~20) or glucose (GI~89) drinks prior to (300 ml) and at every 15 min during a low intensity steady state jog at 65% of their VO2Peak
  
  Note: I guess, it goes without saying that 45g of galactose this is more galactose than you can stomach from ingesting any "high galactose" foods; see table on the right, data in g/100g).
  The scientists measured the substrate oxidation, postexercise satiety and subsequent energy intake on three occasions (GLU, GAL, placebo) and found that
  • the plasma glucose levels were significantly greater throughout the exercise and in the rest period, when the subjects ingested the glucose drink,
  • there were no differences in carbohydrate oxidation, and
  • perceived hunger was significantly lower throughout the galactose compared to both the glucose and placebo trials
  What may yet be most significant for the average trainee trying to shed some weight is the difference in net energy balance, i.e. the difference between energetic costs of the workout, on the one hand, and the energy intake from the glucose / galactose supplement and the food intake during the post-exercise ad-libitum test lunch and the remainder of the day, which was negative only in the placebo and the galactose trial.

  ---

  Bottom line: If you want to shed some body fat and cannot go without an intra-workout beverage pick galactose over glucose, but do a "test run" before you try that in public - the monosaccharide is notorious for its socially not acceptable effects on the evaporations from your gastrointestinal tract ;-)

"Does the Usefulness of Vitamin E Supplementation Depend on Your Activity Level?" It is possible that only those benefit who are already overtaxing their system and will thus need additional protection (learn more)

• Exercise is stressing, but the long-term results are what's associated with improved antioxidant capacity (Lundström. 2013) The data Lundström et al. have collected in their recent 3-week trial involving fourteen 26-year-old volunteers who performed two "strenuous" (intensity targeted to 75% of VO2max) endurance training sessions per day (6 days a week) does in a way underline the validity of the hormesis hypothesis. Despite the fact that the increase in oxidative stress in response to the the allegedly hefty (for non professional athletes) two-sessions a-day, 6-days a week was not significant, the latter was facilitated / buffered by highly significant declines in the total plasma antioxidant capacity (AO).
  
  However, aside from the fact that the AO levels did not fully return to baseline after the subsequent 4-week recovery period, the most intriguing results of the study at hand is the highly significant negative (meaning "if A is high, B is low") correlation between fat-free mass and oxygen uptake, on the one hand, and oxidation stress, on the other.

  ---

  Bottom line: With both of the former, i.e. fat-free mass and oxygen uptake while you exercise, being hallmark features of physical fitness you cannot increase without working out, the balancing act, every trainee has to master is to find the exact i +1 load of stress that allows for adequate recovery and super-compensation in the time to the next workout / mesocycle.

• Low Immunoglobuli, high cortisol and health While there appears to be a general relation between suppressed sIgA and high cortisol levels, on the one hand, and ill-health effects on the other. The latter is not sports-specific (Volkmann. 2006), and elite athletes are, despite suppressed IgA levels capable of normal responses to novel oral vaccinations, "indicating that mucosal immune mechanisms are intact" (Gleeson. 2000).
  Astaxanthin supplementation can ameliorate minor sIgA dump in athletes (Baralic. 2013) Study shows, supplementation with 4mg/day of astaxanthin can ameliorate the decrease in sIgA (marker of immune health) in young soccer players following 2h of exercise.
  
  There are yet two things you have to consider, when you read studies like these:  (a) Scientific evidence of the significance of immunoglobolin measures is not fully conclusive, and (b) the changes placebo group were not even significant.

  ---

  Note: In view of the fact that "[t]he clinical significance of [immunoglobolin changes] in acquired immunity with acute exercise and training remains unknown" (Walsh. 2011), the scientists' conclusion that "astaxanthin supplementation might serve as a countermeasure to sIgA changes associated with continuous intense training", must be taken with some caution wrt to its real-world benefits. 

• Citrulline shifts substrate utilization towards carbs (Faure. 2013) With this last item in today's Exercise Science Potpourri, we are actually coming back to the an issue that has been in the SuppVersity news pretty regularly as of late: the amount fat / glucose you burn during a workout. I guess, I have made my personal perspective that fatty acid oxidation rates during exercise are hilariously overrated pretty clear. This does yet not stop me from pointing you towards the results of a soon-to-be-published study from the Université Paris Descartes the results of which would suggest that supplemental citrulline could work as a "fuel switch".
  
  

  

  Do you remember the December 2011 SuppVersity news on citrullines anti-catabolic effects (go back!)

   The significant downregulation of oxidative enzymes from the Krebs cycle and mitochondrial respiratory chain, the French scientists observed in a group of male Sprague-Dawley rats, when theyy re-fed them after a 12-week period of dietary restriction with a citrulline supplemented diet (+5g/kg chow and thus equivalent to what human studies have been using) compared to the standard chow with an iso-caloric mix on non-essential amino acids added) would at least suggest that "citrulline supplementatio [...] seems to induce a switch in muscle energy metabolism, from aerobia towards anaerobia" (Faure. 2011).
  
  Now, I did already point out that this is not necessarily a bad thing, but they cannot - as you may speculate now - explain the beneficial effects the original NO-supplement ingredient l-arginine on blood glucose management (learn more), because Faure et al. were able to show that "citrulline action is not direct and is not related to arginine" (Faure. 2013).

  

  Figure 1: Activity of enzymes involved in the oxidation of fatty acids; data expressed relative to baseline levels  on ad-libitum diet (Faure. 2013)

  Against that background another effect that was brought about by the high citrulline diet could yet be even more of a major metabolic disadvantage: The increase in metabolically highly glucoes guzzling unflexible type-IIb fibers (see figure 1; learn more), which has been associated with low / non-existent adiponectin levels by Krause et al. (2008).

  ---

  We have to be careful though, with respect to the interpretation and potential implications of these results. Why? Well, there are actually countless reasons: (a) Human beings are no rodents and normal rodents are no athletes, (b) the potential impact of a higher baseline protein intake or the absence of the calorie restriction before the supplementation period (c) different short (study at hand = 1 week) vs. long-term effects, (d) the possible (beneficial ?) involvement of mTOR, which has been shown to be activated by citrulline in previous trials (cf. SuppVersity Dec 28, 2011 and/or Le Plénier. 2011) (e) the fact that some athletes may benefit from the same shift towards glucose and the relative increase in type IIb fibers (not bodybuilders, though!) (f) ... I could go on with this list, but I guess you will see that there is no reason to panic.
  
  Take the Faure study as further evidence for our lack of understanding of the the complex effects and interplay of nutritional and supplemental amino acids on our health and don't forget to come back to the SuppVersity if you want to keep up with the "state of the art" ;-)

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That's it for today! I hope you enjoyed the "ride" and stay tuned for future exercise, nutrition and health science potpourris - write-ups of which I believe they are a necessary and interesting intermediate between the mini-items on Facebook (don't forget to head over there and check out today's 9+ news items) and the elaborate "regular" SuppVersity articles.

References:

• Baralic I, Đorđević B, Đuričić I, Šobajić S, Stanković I, Dikić N (2013). Salivary IgA response to astaxanthin supplementation in young soccer players. Proceedings of the Nutrition Society, 72, E7.
• Carlsohn A, Heydenreich J, Engel T, Kratzenstein S, Mayer F. Does immediate carbohydrate intake following glycogen-depleting exercise affect next day’s 5000 m time trial performance? International Journal of Sport Nutrition and Exercise Metabolism.  2013; 23(S1 -S15).
• Duckworth LC, Backhouse SH, Stevenson EJ, O’Hara JP. Effect of galactose ingestion before and during exercise on substrate oxidation and subsequent energy intake in females. International Journal of Sport Nutrition and Exercise Metabolism.  2013; 23(S1 -S15).
• Le Plénier, S., Walrand, S., Noirt, R., Cynober, L., Moinard, C., Effects of leucine and  citrulline versus non-essential amino acids on muscle protein synthesis in fasted rat: a common activation pathway? Amino Acids. 2011.
• Krause MP, Liu Y, Vu V, Chan L, Xu A, Riddell MC, Sweeney G, Hawke TJ.Adiponectin is expressed by skeletal muscle fibers and influences muscle phenotype and function. Am J Physiol Cell Physiol. 2008 Jul;295(1):C203-12. 
• Stuart CA, McCurry MP, Marino A, South MA, Howell ME, Layne AS, Ramsey MW, Stone MH. Slow-Twitch Fiber Proportion in Skeletal Muscle Correlates with Insulin. Responsiveness. J Clin Endocrinol Metab. 2013 Mar 20. 
• Volkmann ER, Weekes NY. Basal SIgA and cortisol levels predict stress-related health outcomes. Stress and Health. 2006; 22: 11–23. 
• Walsh NP, Gleeson M, Shephard RJ, Gleeson M, Woods JA, Bishop NC, Fleshner M, Green C, Pedersen BK, Hoffman-Goetz L, Rogers CJ, Northoff H, Abbasi A, Simon P. Position statement. Part one: Immune function and exercise. Exerc Immunol Rev. 2011;17:6-63. Review.

Does Creatine Blunt Fat Loss? A Recent Study Supports Long-Standing Suspicions, But What Are the Implications?

Better  lean than strong? Why not both?

Anyone remember the allegedly not very popular post on the "anti-creatine" β-Guanidinopropionic Acid (GPA) and it's ability to increase AMPK, decreases blood glucose & insulin, induce weight loss without dieting, increase skeletal muscle oxidative capacity and delay the development of mammary cancer (read up on the news)? I thought so...

Even I had was just about to forget about it, when I stumbled upon a recently published Brazilian study which found that the "real" - not the anti-creatine - does in fact what you would expect from the "evil twin" of GPA: It blunts the exercise induced fat loss in highly trained amateur athletes (Manjarrez-Montes de Oca. 2013).

"What!? Creatine makes me fat?"

Now, before you start freaking out, let me say this: There are also studies which suggest that creatine supplementation does the exact opposite, i.e. that it can (combined with an intense exercise protocol) decrease body fat level (van Loon. 2003; Volek. 2004). If you dig deeper, you will yet find that most studies actually don't report any changes in the ratio of fat to total body mass most of you know as "body fat percentage" (Kreider. 1998; Volek. 1999; Becque. 2000).

Whatever the results of the individual experiments may be, in the end only studies like the one done by Jeff Volek et al. at the University of Connecticut or the study at hand, i.e. studies in the course of which the scientists actually measure/d the total amount of lean and fat mass can provide an adequate idea of what exactly supplemental creatine can do for our physiques. If the data includes only body fat percentages, maybe even measured with bio-impedance (→ yesterday's Facebook news on "losing" 1.4% of body fat in a single session), this does not suffice to say, whether the absolute amount of body fat changed. Or in other words, whether any observed increase / decrease in body fat (%) was simply a result of the fact that the ratio of lean to total body mass increased faster than the rate of fat to total body mass, wile the subjects abs still disappeared under a nasty layer of blubber.

Figure 1: Changes in body mass, bone free lean mass, fat mass and body fat percentage (left), as well as individual "fat gain" response to creatine supplementation in the 14 subjects (Manjarrez-Montes de Oca. 2013).

The study at hand is in fact a perfect example for the way body fat  levels alone can fool you. A brief glance at the data in figure 1 confirms that. While the body fat percentage says that the 12 non-smoking, non-vegetarian, red and black belt male recreational taekwandoo players must effectively have lost weight in the creatine phase of this, the total fat mass reveals that adding 50mg/kg creatine to their sports drink (30 g of sucrose, artificial flavor, 500ml) lead to an increase, the addition of the same amount of maltodextrin to a decrease in DEXA measured total body fat.

If it were not for the results of of 2002 paper by Huso, I guess, I would just tell you to simply forget about the hoopla and discard the notion that creatine would have any effect on body fat levels, at all (Huso. 2002). Huso et al. had investigated the influence of creatine supplementation (20 g/day for 4 days, then 2 g/day for 17 days) on substrate utilization during rest using a double-blind crossover design. To this ends the researchers recruited 10 active men who participated in a 12 wk resistance training protocol (3x /week full body resistance training; 3 sets, 10 reps) involving a placebo and a creatine trial that were separated by a 4-wk washout.

Figure 2: Changes in body composition (body mass, body fat and fat free mass) and 1RM strength on the bench press and leg press in the 12-week double-blind randomized cross over trial by Huso et al. (Huso. 2002)

Very similar to Manjarrez-Montes de Oca et al. in the study at hand,  Huso et al. observed a significant decrease in fat mass (-2.4kg) in the placebo trial, while there were no significant changes in either of the two parameters, when the subjects were "on creatine".

So how come that creatine does even have the ability to inhibit fat loss?

Just like the identical change in lean mass (in fact, only the strength increase speaks in favor of the creatine loading + maintenance regimen) the inhibition of the fat loss in the trial of the Huso study was actually only a "side finding". Originally, Huso et al. had set out to elucidate, whether the "anecdotal evidence of weight gain, including a lack of fat loss, in persons taking creatine" (Huso. 2002) could be brought about by creatine induced increases / decreases of the respiratory exchange ratio (RER = the ratio of carbohydrates to fats that are oxidized during a workout). And while the scientists state in their abstract that the "[c]hanges in substrate oxidation" they observed "may influence the inhibition of fat mass loss associated with creatine after weight training" (Huso. 2002), it is at least in my humble opinion not very likely that the small statistically only borderline significant shift from fat to carbohydrate oxidation (+/- 9%, respectively) alone can actually explain the >2kg difference in total fat mass loss. Still, this is exactly what Manjarrez-Montes de Oca et al. feel would be the most likely explanation for the observations they made 11 years later, as well:

I wonder if Usain Bolt consumes creatine supplements. Or is he on GPA, click here to learn what would be more likely.

"It has been suggested that the increase in carbohydrate utilization induced by Cr may be due to an activation of the enzyme phosphofructokinase, which produce an increase in glucose utilization, with elevation of malonyl-CoA and inhibition of carnitine palmitoyltransferase 1 (CPT1) system, which transports fatty acids into the mitochondria for oxidation (Huso. 2002).

If fatty acids are not transported into the mitochondria of skeletal muscle cells to be oxidized, they could be expected to be maintained in blood as triglycerides; and then stored in the adipose tissue.

We observed a higher concentration of triglycerides after Cr supplementation, and also found that subjects after Cr treatment gained fat mass whereas after placebo treatment fat was lost. Therefore, both findings could imply that fatty acid mitochondrial uptake has been inhibited by Cr ingestion, altering the normal fat loss produced by TKD training."

What you should keep in mind though, is that the dietary intake was not controlled for (what if increased glucose oxidation simply made the subjects hungrier?). In calorically restricted scenario the results could thus have been very different, so that it is overall not very likely that creatine would ruin your dieting efforts. Moreover, there is some, allegedly not very conclusive evidence that the addition of a reasonable amount of creatine to your diet could actually help you spare muscle tissue. The fact that the placebo-specific increase in protein oxidation from 11.6% to 15.3% was just as absent in the creatine group as the fat loss, is however hardly a convincing, let alone bullet-proof argument in favor of creatine as a dieting aid. After all the protein oxidation in the creatine group remained stable on the same high levels of roughly 15%.

---

Bottom line: I don't feel that the evidence "against" taking reasonable amounts of creatine (2-3g per day) is conclusive enough to panic and give up on the possible beneficial effects on lean mass (Nissen. 2003; Poortmans. 2010). Still, if you really have good reason to believe that creatine may blunt your fat loss (it's not impossible, take a look at the "high responders" in figure 1, right), I don't see why you could not give it a try and simply stop taking your creatine for a months or so. If after an initial flattening effect you don't see any other changes in your physique you are at least sure that you don't belong to the unlucky few, for whom creatine monohydrate (not one of the sugar-laden combi products!) could maybe and due to whatever interaction of genes, diet and whatever other confounding factors, forestall fat loss.

References:

• Becque MD, Lochmann JD, Melrose DR. Effects of oral creatine supplementation on muscular strength and body composition. Med Sci Sports Exerc. 2000 Mar;32(3):654-8.
• Huso ME, Hampl JS, Johnston CS, Swan PD. Creatine supplementation influences substrate utilization at rest. J Appl Physiol. 2002 Dec;93(6):2018-22.
• Kreider RB, Ferreira M, Wilson M, Grindstaff P, Plisk S, Reinardy J, Cantler E, Almada AL. Effects of creatine supplementation on body composition, strength, and sprint performance. Med Sci Sports Exerc. 1998 Jan;30(1):73-82.
• Manjarrez-Montes de Oca R, Farfán-González F, Camarillo-Romero S, Tlatempa-Sotelo P, Francisco-Argüelles, Kormanowski A, González-Gallego J, Alvear-Ordenes I. Effects of creatine supplementation in taekwondo practitioners. Nutr Hosp. 2013;28(2):391-399.
• Meglasson MD, Wilson JM, Yu JH, Robinson DD, Wyse BM, de Souza CJ. Antihyperglycemic action of guanidinoalkanoic acids: 3-guanidinopropionic acid ameliorates hyperglycemia in diabetic KKAy and C57BL6Job/ob mice and increases glucose disappearance in rhesus monkeys. J Pharmacol Exp Ther. 1993 Sep;266(3):1454-62.
• Nissen SL, Sharp RL. Effect of dietary supplements on lean mass and strength gains with resistance exercise: a meta-analysis. J Appl Physiol. 2003 Feb;94(2):651-9. Epub 2002 Oct 25.
• Poortmans JR, Rawson ES, Burke LM, Stear SJ, Castell LM. A-Z of nutritional supplements: dietary supplements, sports nutrition foods and ergogenic aids for health and performance Part 11. Br J Sports Med. 2010 Aug;44(10):765-6.
• van Loon LJ, Oosterlaar AM, Hartgens F, Hesselink MK, Snow RJ, Wagenmakers AJ. Effects of creatine loading and prolonged creatine supplementation on body composition, fuel selection, sprint and endurance performance in humans. Clin Sci (Lond). 2003 Feb;104(2):153-62.
• Volek JS, Duncan ND, Mazzetti SA, Staron RS, Putukian M, Gómez AL, Pearson DR, Fink WJ, Kraemer WJ. Performance and muscle fiber adaptations to creatine supplementation and heavy resistance training. Med Sci Sports Exerc. 1999 Aug;31(8):1147-56.
• Volek JS, Ratamess NA, Rubin MR, Gómez AL, French DN, McGuigan MM, Scheett TP, Sharman MJ, Häkkinen K, Kraemer WJ. The effects of creatine supplementation on muscular performance and body composition responses to short-term resistance training overreaching. Eur J Appl Physiol. 2004 May;91(5-6):628-37.