Resistant Starch (RS4) for Fat Loss & Exercise Performance

Resistant Starch (RS4) for Fat Loss & Exercise Performance

cycling lose fat performance resistant starch RS RS4

RS4 is still relatively difficult to come by. Options I know of are ActiStar® from Cargill and Fibersym® fom MGP. RS2 and RS3 alternatives are raw potato starch and, as previously discussed, banana starch or reheated starches. They'll have (presumably) very similar effects, but come directly from food.

You will probably remember the good old "Waxy Maize Reloaded" article from 4 years ago that caused quite a stir!? Well, I guess four years is a long time - more than enough to revisit the idea of designer resistant starches and their effect on your physique and performance. To do so, I've picked two recent studies from the South Dakota State University (Upadhyaya. 2016) and the Florida State University (Baur. 2016) that have one thing in common: they add to the hitherto still inadequate number of studies on resistant starch type 4 (RS4), one out of five forms of "resistant", i.e. (partly) undigestible, starches with significantly different chemical properties and corresponding functional differences such as their fermentability or their influence on the microbiota in the gut and their applicability as ergogenics in sports drinks and/or functional foods.

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To elucidate the effects on the gut microbiome and the production of health-relevant short-chain fatty acid (SCFA) production, of which the previously cited article about WM-HDP from 2012 explains how they affect GLP-1, glycemia and metabolism (read it), Upadhyaya et al. conducted an experiment with twenty individuals with signs of, but not fullly established metabolic syndrome (MetS).

Table 1: Overview of the study design (Upadhyaya. 2016).

With a total duration of 26 weeks that included two 12-week interventions periods, with one each for RS4 (30%, v/v in flour that is currently not available in supermarkets) and control flour (CF), and a two-week washout in between the interventions, the randomized cross-over study is one of the longest dietary interventions with any form of resistance starch I have read and thus also the one with the highest potential of yielding relevant insights into the long-term effects of RS-4 consumption. As previously pointed out, ...

"[...] all twenty participants who had signs of metabolic syndrome at baseline and submitted adequate stool samples at four data collection time points were included in the current investigation, which allowed for comparison of the gut microbial and SCFA profiles before and after the interventions and also between the endpoints of the RS4 and CF (control) interventions" (Upadhyaya. 2016). 

In view of the fact that adverse gastrointestinal side effects from the interventions were not evaluated in this cohort, we have to simply follow the scientists' reasoning that no bloating, belching or other unwanted sides would occur - an assumption that appears to be at least reasonable in view of the observations the scientists made in a previous study w/ similar design (Nichenametla. 2014).

The visible performance decrements in the low HMS group was sign. correlated with gastrointestinal distress (Baur. 2016).

What about performance? Those were evaluated by Daniel A. Baur in a study which investigated the metabolic and gastrointestinal effects of a hydrothermally-modified starch supplement (HMS) before and during cycling for ~3 h (1 h at 50% Wmax, 8 x 2-min intervals at 80% W max, and 10 maximal sprints) in 10 in male cyclists who underwent three nutritional interventions (crossover design): (1) a commercially available sucrose/glucose supplement (G) 30 min before (60 g carbohydrate) and every 15 min during exercise (60 g/h); (2) HMS consumed at the same time points before and during exercise in isocaloric amounts to G (Iso-HMS); and (3) HMS 30 min before (60 g carbohydrate) and every 60 min during exercise (30 g/h; Low HMS).

Interestingly enough, the supplement had no effects on sprint performance with Iso HMS vs. G, being identical and G and Iso HMS resultin in nothing but a "likely", yet small performance enhancement of 5.0% compared to the "low carb" = Low HMS trial.

What may  be considered a success, though, is the sign. increase in fat oxidation (31.6%+/-20.1%; very likely (Iso); 20.9%+/.16.1%; likely (Low)) and corresponding reduction in carbohydrate oxidation (19.2%+/-7.6%; most likely; 22.1%+/-12.9%; very likely) during exercise relative to the plain glucose trial (G). That the latter was dearly bought by increased during repeated sprints with ingestion of Iso HMS (17 scale units +/-18; likely) and Low HMS (18 +/-14; likely) that also explained the decreased performance with Low HMS vs. G (likely), future studies will have to either find ways to make HMS more gut friendly or test whether the repeated administration of HMS solves the issue by the means of intestinal adaptation - a corresponding study could also yield insights into whether the increased fatty oxidation would also trigger long-term mitochondrial growth that goes beyond what you'd see with regular Gatorade aka a sugar-containing workout beverage.

I know that you will probably me most interested in the effects on the subject's body composition. Therefore I plotted those in Figure 1 and postponed the presentation and discussion of the authors' actual research interest, the microbial composition of their subjects guts on a later paragraph.

Figure 1: Effects of control and RS4 diet on body composition and lipid variables (Updahyaya. 2016).

As you can see, the consumption of the RS4 diet had significant (beneficial) effects on the subjects' waist lines (~2% or 2 cm vs. baseline and control). In conjunctions with the beneficial effects on HDL (p = 0.001) and total cholesterol (p = 0.01), which were 10% higher and lower, respectively, after the RS4 vs. control diets, and a significant increase in adiponectin (p < 0.01), and none-significant improvements in fasting blood glucose (+5% and -4% vs. baseline in control and RS4, respectively) and HbA1c (-1% and -2% vs. baseline in control and RS4, respectively), there appears to be little doubt that the significant improvement in the firmicute to bacteriode ratio, which is frequently perceived as an indicator of a leaner phenotype (although the previously reported results are not always consistent | Fernandes. 2014) in the RS4 weeks, as well as specific results, such as ...

• the previously observed increase of species from Clostridial cluster XIVa, but not cluster IV, that was triggered by RS4 supplementation of the diet; at the species level, RS4 consumption increased the abundance of Bifidobacterium adolescentis (90.5 fold, q= 0.087) and Parabacteroides distasonis (1180.2 fold, q< 0.001) but not Ruminococcus bromii (−3.2 fold, q > 0.05), Faecalibacterium prausnutzii (−1.2 fold, q > 0.05), or Dorea formicigenerans (1.1 fold, q> 0.05)

• 

  Timing Matters if You Want to Turn Regular into Resistant Starch | more

  a not previously observed RS4-induced increase in Christensenella minuta abundance (119.7 fold, q= 0.038, 97% query coverage, 88% identity and E< 0.001 in NCBI-BLAST) as well as in several OTUs in the family Ruminococcaceae and genus Bacteroides; at the species level, Bacteroides ovatus (37.6 fold, q= 0.087), Ruminococcus lactaris (2866.7 fold, q< 0.001), Eubacterium oxidoreducens (3.3× 105 fold, q< 0.001), Bacteroides xylanisolvens (47.8 fold, q= 0.037), and Bacteroides acidifaciens (92.4 fold, q= 0.038) were enriched after RS4 intervention
• changes in the individual proportions of the SCFAs, butyric (69.5%, p= 0.03), propionic (50.2%), valeric (44.1%), isovaleric (20.3%), and hexanoic (19.2%) acids increased post intervention from baseline in the RS4 group (p< 0.05) but not in the CF group (data not shown)
• correlations between significant changes in the gut microbiota composition induced by RS4 and altered SCFA level that were not observed after the control treatment

provide reasonable evidence for the use of RS4 as a food additive (in place of regular starches, obviously). In that, it is also important point out is that the changes in body composition, lipoproteins, glucose control and the bacterial composition of the subjects' microbiome occured in the absence of significant differences in macronutrient intake,... well, aside from the dietary fibre intake, which was obviously significantly higher in the RS4 group (p< 0.001). After all, RS4 is officially being classified as a prebiotic dietary fibre.

Figure 2: Differential gut microbial composition after RS4 intervention at the species level (left) and correlations with important metabolic outcomes from total cholesterol (TC) to adiponectin (right | Upadhyaya. 2016).

Overall, the average calories (~1,774 Kilocalories) consumed at baseline were estimated to come from carbohydrate (~49%), protein (~17%), and fat (~34%) - values you may criticize, but of which the authors rightly point out that they "fall within the Dietary Reference Intakes (DRI) for macronutrients, which are 45–65%, 10–35%, and 20–35% for carbohydrate, protein, and fat", respectively.

Is RS4 different from other prebiotics?It obviously is structurally different, so it is not 100% surprising that a previous parallel design study u-sing other prebiotics, na-mely inulin and oligofruc-tose, suggests that the ensuing improvement in metabolic functions and body composition are more pronounced with RS4 compared to other prebiotics.

Bottom line: In sum the two studies provide reasonable evidence for the addition of RS4 to your diet and/or functional foods. There is one thing you should keep in mind: the potential ergolytic effect that comes with the intestinal side effects in those who cannot handle the RS4-laden Gatorade alternative. Before you buy a few pounds of RS4 at the bulk-supplier of your trust, you should thus better test-drive your individual RS4 tolerance.

Since similar effects were not observed by Nichenametla and Updahyaya in their 2014 and 2016 studies, it is yet safe to assume that this effect may be exposure dependent with the use of  30% v/v RS4 in flour - a strategy that could also be employed in processed foods having no significant effect on the digestive health of the average customer, but a sign. effect on his waist circumference | Comment!

References:

• Baur, Daniel A., et al. "Slow-Absorbing Modified Starch before and during Prolonged Cycling Increases Fat Oxidation and Gastrointestinal Distress without Changing Performance." Nutrients 8.7 (2016): 392.
• Dewulf, Evelyne M., et al. "Insight into the prebiotic concept: lessons from an exploratory, double blind intervention study with inulin-type fructans in obese women." Gut (2012): gutjnl-2012.
• Fernandes, J., et al. "Adiposity, gut microbiota and faecal short chain fatty acids are linked in adult humans." Nutrition & diabetes 4.6 (2014): e121.
• Nichenametla, Sailendra N., et al. "Resistant starch type 4‐enriched diet lowered blood cholesterols and improved body composition in a double blind controlled cross‐over intervention." Molecular nutrition & food research 58.6 (2014): 1365-1369.
• Upadhyaya B, et al. "Impact of dietary resistant starch type 4 on human gut microbiota and immunometabolic functions." Sci Rep. 2016 Jun 30;6:28797. doi: 10.1038/srep28797.

Caffeine & Bicarbonate - Individuality is Key: Using Supps That Work for You Make a >90% Performance Difference

Caffeine & Bicarbonate - Individuality is Key: Using Supps That Work for You Make a >90% Performance Difference

bicarbonate caffeine cycling endurance ergogenic ergogenics NAHCO3 natural ergogenic performance sodium bicarbonate time to exhaustion

Right vs. wrong supps can make a victory or defeat difference of >90%.

I've written about the individual response to caffeine and bicarbonate before. To tackle both of these ergogenic supplements I can actually recommend, however, based on a single study that as just been published in the Applied Physiology, Nutrition, and Metabolism is news. The study was conducted at the Derby University's Department of Life Sciences, Sport, Outdoor & Exercise Science (Higgins. 2016) and evaluated the effects of ingesting sodium bicarbonate (NaHCO3) or caffeine individually or in combination on high-intensity cycling capacity.

In a counterbalanced, crossover design, 13 healthy, noncycling trained males (age: 21 ± 3 years, height: 178 ± 6 cm, body mass: 76 ± 12 kg, peak power output (Wpeak): 230 ± 34 W, peak oxygen uptake: 46 ± 8 mL·kg−1·min−1) performed a graded incremental exercise test, 2 familiarisation trials, and 4 experimental trials.

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Trials consisted of cycling to volitional exhaustion at 100% W peak (TLIM) 60 min after ingesting a solution containing either

• 0.3 g·kg−1 body mass sodium bicarbonate (BIC), 
• 5 mg·kg−1 body mass caffeine plus 0.1 g/kg body mass sodium chloride (CAF), 
• 0.3 g·kg−1 body mass sodium bicarbonate plus 5 mg/kg body mass caffeine (BIC-CAF), or 
• 0.1 g·kg−1 body mass sodium chloride (PLA). 

Experimental solutions were (supposedly) administered double-blind (which is difficult imho, because bicarb and salt taste different, but alas).

Figure 1: Tabular overview of the rate of perceived exertion (RPE_L = legs, RPE_O = overall cardiovascular strain | left) and blood pH over time (right) during the four trials (Higgins. 2016).

The first and most obvious effect of treatments (BIC) and (BIC-CAF) was a significant increase in pH, base excess, and bicarbonate ion concentration ([HCO3−]) compared to the CAF and PLA trials.

Another new study supports lower dose (0.3g/kg) bicarbonate for resistance training: The study was conducted by a Bachelor student from the University of Tempa. The purpose of the study was to investigate whether the ingestion of sodium bicarbonate (SB) pre-exercise improved athletic performance during resistance training (RT) and reduced fatigue in male college students. In the study, ,ale college students performed 1RM and endurance tests before their own individualized RT program 4 times a week during the 4 week study. The SB group produced higher increases in mean weight used in each of the 1RM tests (P < 0.05) compared to the placebo group. The SB group also produced a higher amount of repetitions in the IDP, LP, and LPD endurance tests (P < 0.05). There was a significant difference in each self-report scale (P < 0.05) between the SB group and the placebo group. "These findings suggest that the supplementation of SB prior to RT in college male students could enhance performance," (Indorato. 2016) the author concludes.

The effect on TLIM (time to volitional exhaustion) was unfortunately less obvious - for all three active treatments, by the way. When all subjects were considered, ...

• 

  A high amount of alkali in your diet could have general health and performance benefits | learn more

  there was a significant increase in TLIM for CAF (399; 350–415 s; P = 0.039; r = 0.6) and BIC-CAF (367; 333–402 s; P = 0.028; r = 0.6), but only compared with BIC (313: 284–448 s), yet not compared with PLA (358; 290–433 s; P = 0.249, r = 0.3 and P = 0.099 and r = 0.5, respectively), 
• there were no differences between PLA and BIC (P = 0.196; r = 0.4) or between CAF and BIC-CAF (P = 0.753; r = 0.1), and 
• there was no effect whatsoever on the rate of perceived exertion (RPE | Figure 1, left).

The "average" effect does yet not tell you the full truth about the potential ergogenic effects of caffeine and bicarbonate. Why? Higgins et al. found very large inter- and intra-individual variations, when they compared the individual treatments (see Figure 2, right).

Figure 2: Mean +/- SD (left) and individual (right) response to the treatments (Higgins. 2016).

Accordingly, the scientists rightly highlight that optimal supplementation strategies require individualization. Using supplements that work for you can, after all, make a performance difference of 81%, 92% and 63% (max. vs. min responders) for bicarbonate, caffeine and the combination of both (all values relative to T_LIM in the placebo trial).

Caffeine has many benefits, but also potential downsides you should know about to make an educated decision based on science and your individual response to caffeine | learn more

Fine. So shall I use bicarbonate and caffeine or not? I cannot tell you that. Why? Well, it depends on how you react to these proven ergogenics. The only way to find out is to testdrive both - on their own and together. Plus: A study investigating the maximal cycling time at 100% of your peak wattage doesn't tell you sh*t about the effects on your performance during other physical activities like resistance training (the study in the red box, does, though).

Luckily, the new study by Indorato is not the only one to show bicarbonate (example) has, just like caffeine, by the way (example), ergogenic effects . This doesn't mean that either of them will necessarily work for you, but it is a good reason to trial both | Leave a comment on Facebook!

References:

• Higgins, et al. "Evaluating the effects of caffeine and sodium bicarbonate, ingested individually or in combination, and a taste-matched placebo on high-intensity cycling capacity in healthy males." Appl. Physiol. Nutr. Metab. (2016).
• Indorato, Daniel. "Enhanced Resistance Training Performance via the Neutralization of Lactic Acid with Sodium Bicarbonate." Student Pulse 8.03 (2016).

GYM-Science Update: Bands Aid W/ Deadlifts? 16x1 or 4x4 for HIIT? Kettlebell HIIT Workout Better Than HIIT-Cycling?

GYM-Science Update: Bands Aid W/ Deadlifts? 16x1 or 4x4 for HIIT? Kettlebell HIIT Workout Better Than HIIT-Cycling?

bands cycling deadlift high intensity HIIT interval training intervals kettlebells lose fat on short notice performance rest intervals workout routines workouts

Deadlifts w/ bands as they were done in the Galpin study (original photo from Galpin's 2015 study | see below).

Time for a news-quickie with the latest science to use at the gym - either for your workouts or just to impress the bros with your knowledge. I mean, who else reads and understands all the latest papers in the #1 strength and conditional journal on earth? Well, you do... ok, you read my laymen summaries, but your bros don't have to know that, do they?

Ok, that's enough of the pseudo-comedian warm-up, let's deadlift the first scientific paper... oh,yeah: Actually the paper is about deadlifting, deadlifting with resistance bands as it is shown in the photo on the right, where a subject performs the deadlift on a force plate.

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• Deadlift with bands for power and speed - Galpin et al. (2015) investigated how using bands while deadlifting at different loads, namely 60 and 85% of one's individual 1RM, i.e. the maximal weight you can lift for exactly one perfect rep, would influence the power and velocity at which twelve trained men (age: 24.08 ± 2.35 years, height: 175.94 ± 5.38 cm, mass: 85.58 ± 12.49 kg) with deadlift 1 repetition maxima (1RM) of 188.64 ± 16.13 kg pulled the weight off the floor.
  
  The results of the study show that there were significant peak (yet not relative) power changes irrespective of whether only 15% of the total resistance (group B1) or 35% of the total resistance (group B1) came from the bands (vs. the actual weight).
  

  

  Figure 1: Relative changes in power and bar velocity (compared to training w/out bands = control); * denotes sign. difference to control, ** denotes significant difference to control and light bands (Galpin. 2015)

  The effect became even more pronounced and extended from peak to average power, when the subjects used the heavier (85% 1RM) weights. In this condition using bands lead to greater peak and relative power production and lowered the velocity significantly compared to the control condition in which the subjects lifted at the same total level of resistance, albeit without bands (all values in Figure 1 are relative differences).
  
  For trainees the data in Figure 1 could be highly relevant, because it indicates that heavy bands should be used, when "prescribing the deadlift for speed or power, but not maximal force" (Galpin. 2015). If that's not you, i.e. you're not training for speed and power, but e.g. for size, future long(er)-term studies will have to show whether using bands makes a difference with respect to this study training goal.
• Interval length, can you really pick whichever suits your best? Even though a recent study by Wesley Tucker et al. (2015) shows that the rate of perceived exertion, as well as the mean heart rate of 14 recreationally active and thus not exactly jacked males who participated in their latest study were identical on 4x4 and 16x1 high intensity interval protocols (i.e. 4 intervals à 4 minutes vs. 16 intervals a 1 minute | see Figure 2), seasoned SuppVersity readers will probably remember that previous studies showed highly relevant differences in the long(er) term effects which obviously cannot be measured in an acute phase study like the one at hand.
  

  

  Figure 2: Illustration of the two HIIT protocols, incl. warm-up and cool down on cycle ergometers. White boxes are intervals during which the subjects were supposed to exercise at 90% of their peak heart rate (during the 16x1 protocol this was not achieved by all study participants in the latter intervals, though | Tucker. 2015).

  To be more specific, previous studies on high intensity interval training suggested that athletes who want to increase their VO2 max benefit more from fewer longer intervals, while "Mr. and Mrs. Average" could be better off improving their body composition and metabolic rate with a higher number of short intervals (even as short as 15 seconds in the Tabata protocol). Against that background and in order to explain or contradict the previous findings, it may be worth to consider other study outcomes in Tucker et al. (2015). Study outcomes which did differ. The total energy expenditure, for example, was 19% higher during the 16x1 protocol (p < 0.001) which is in line with the previously referenced recommendation of short intervals for people who are trying to lose weight.
  

  

  Figure 3: VO2, heart rate, and energy expenditure during the two HIIT protocols (watch the units! I converted them to be able to put all data into the same graph | Tucker. 2015).

  The VO2 uptake, as well as the maximal heart rates, which could be of interest for endurance athletes, on the other hand, were higher in the 4x4 protocol - a finding that would likewise support the previously voiced recommendation that (endurance) athletes should torture themselves with long(er) intervals to trigger further adaptations in VO2max and heart rate at a given power output.
  
  Overall, the study at hand will thus not revolutionize your training, but if you haven't read the previous SuppVersity articles, you may still have gotten some new insights into how you may want to adapt your HIIT training in the future.
• Kettlebell or cycle ergometer? Which do you chose for your HIIT sessions? I've written about kettlebell swings as muscle builders before and I've also hinted at the possibility of using the "bells" for your HIIT workouts. Now, a recent study by Williams and Kraemer shows that

  "[kettlebell high intensity interval training aka] KB-HIIT may [even] be more attractive and sustainable than [sprint interval cycling aka] SIC and can be effective in stimulating cardiorespiratory and metabolic responses that could improve health and aerobic performance" (Williams. 2015).

  The purpose of the study was - you probably already guessed it - to determine the effectiveness of a novel exercise protocol we developed for kettlebell high-intensity interval training (KB-HIIT) in comparison to the classic, standard sprint interval cycling (SIC) exercise protocol most people associate with equipment-based HIIT sessions. To this ends, the researchers from the Southeastern Louisiana University had eight "very active" young men (mean age 21.5 years; body fat 18.52 +/-3.04%, fat free mass 67.44 kg of a total weight of 82.95 kg) complete two 12-minute sessions of KB-HIIT and SIC in a counterbalanced fashion.

  

  Figure 4: Overview of the KB-HIIT workout (my illustration).

  "In the KB-HITT session [exercises see Figure 4, mean weight depending on exercise and subject 10-22 kg], 3 circuits of 4 exercises were performed using a Tabata regimen.

  
  

  In the SIC session, three 30-second sprints were performed, with 4 minutes of recovery in between the first 2 sprints and 2.5 minutes of recovery after the last sprint" (Williams. 2015)

  The study's within-subjects' design over multiple time points allowed Williams and Kraemer to compare the oxygen consumption, the respiratory exchange ratio (RER, a marker of the ratio of fat to carbohydrates that is used as fuel during the workout), the tidal volume (TV, the volume of air that is inspired or expired in a single breath during regular breathing), the breathing frequency (f), the subject's minute ventilation (VE), caloric expenditure rate (kcal/min), and their heart rate (HR) on an individual basis between the exercise protocols. In conjunction with the total caloric expenditure which was likewise measured / calculated and compared. The total amount of data the authors collected was thus quite large.
  

  

  Figure 5: Mean total energy expenditure in kcal during the KB and SIC sessions (Williams. 2015)

  Significant inter-group differences were found for VO2, RER, TV and total energy expenditure, with VO2 and total energy expenditure being higher and TV and RER being lower in the KB-HIIT compared with the cycle ergometer HIIT protocol. For f, VE, the energy expenditure per minute and the heart rate, there were no general inter-group differences, but "only" significant group × time interactions. Practically speaking, this means that they changed differently over the course of the whole protocol and are thus maybe relevant for certain athletes, yet not for the general public.
  
  Overall, the William's and Kraemer's study does therefore support the notion that doing kettlebell HIIT workouts is probably at least on par with the classic cycling HIIT sessions. In view of the increased total caloric expenditure and the lower RER, which signifies a significantly higher fat oxidation during the workout, it is even possible that KB-HIIT would be the better choice for dieters than doing HIIT on a cycle ergometer. Since there is no direct link between fat oxidation and/or energy expenditure during workouts and fat loss, however, long(er)-term studies are necessary to find out whether doing KB-HIIT is in fact more than a equivalent and for many of you maybe funnier alternative to doing HIIT on a cycle ergometer. 

Block Periodization - Training revolution or simple trick? This is what we have to ask ourselves in view of the results of a previously discussed study from 2014 | Read the full SV-Classic article here!

Bottom line: That's it for today; so I suggest you take what you learned, pack it in your gymbag and go and impress your bros at the gym ;-) I am just kiddin'... actually I hope that you can really use some of the information in today's installment of the SuppVersity Short News to make your workouts more productive, more enjoyable and/or simply more versatile.

Personally, I will probably give the KB-HIIT workout a try,... and that even though I expect it to be much harder than cycling which is something I am already used to. But hey, isn't that what training is all about? You have to challenge your body - even if that means conquering your weaker self.

I mean, we all know that as soon as you are staying within the cozy comfort zone of doing the same exercises with the same weights workout after workout your progress will stall; and unless you are one of those people who hit the gym to be able to talk to their athletic friends, that's certainly nothing you should aim for | Comment on Facebook!

References:

• Galpin, AJ, Malyszek, KK, Davis, KA, Record, SM, Brown, LE, Coburn, JW, Harmon, RA, Steele, JM, and Manolovitz, AD. Acute effects of elastic bands on kinetic characteristics during the deadlift at moderate and heavy loads. J Strength Cond Res 29(12): 3271–3278, 2015
• Tucker, WJ, Sawyer, BJ, Jarrett, CL, Bhammar, DM, and Gaesser, GA. Physiological responses to high-intensity interval exercise differing in interval duration. J Strength Cond Res 29(12): 3326–3335, 2015
• Williams, BM and Kraemer, RR. Comparison of cardiorespiratory and metabolic responses in kettlebell high-intensity interval training versus sprint interval cycling. J Strength Cond Res 29(12): 3317–3325, 2015

First Study to Demonstrate Ergogenic Effects of Metformin - 14% Increased Time to Exhaustion in Standardized Supra-Maximal Cycling Test With 500mg of Ordinary Metformin

First Study to Demonstrate Ergogenic Effects of Metformin - 14% Increased Time to Exhaustion in Standardized Supra-Maximal Cycling Test With 500mg of Ordinary Metformin

AMPK cycling doping endurance metformin performance time to exhaustion

With the publication of Learsi's latest paper the list of things metformin can do for you has just gotten been expanded with another item: Doping!

You will probably remember my article about the potential, but unproven ergogenic effects of AMPK mimetics (read it). Well, as it is often the case, a new study is released only days after you've published a review of the existing literature. Oftentimes that's not really relevant, but in the case of the latest study from the Federal University of Alagoas this may be different. After all, we are dealing with a human study in  ten healthy, physically active, but non-athletic subjects with a mean (±SD) maximal oxygen uptake (VO2max) o 38.6 ± 4.5 mL/kg per min who performed (i) an incremental test; (ii) six submaximal constant workload tests at 40%-90% V O2max; and (iii) two supramaximal tests (110% V O2max).

All tests were performed twice once with a placebo supplement and once with 500mg of metformin. Both, the placebo and the metformin supplement were ingested 60 minutes before the supramaximal test, in order to investigate the hypothesis that metformin would increase anaerobic capacity and performance during high-intensity, short-duration exercise.

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The authors, Learsi et al. (2015), based this hypothesis on the fact that metformin inhibits aerobic pathway energy production and so the glycolytic energy system could be overloaded during ATP production for muscle contraction.

Figure 1: Overview of the study design. The active / placebo treatment, i.e. 500mg of metformin or an identically looking placebo were administered 60 min before the supramaximal tests. The whole procedure was repeated twice, with at least 72h between the first and the second testing session (Learsi. 2015).

The aim was thus to to determine the effects of metformin on anaerobic capacity and to elucidate whether metformin has any ergogenic effect in intense, short-duration exercise in healthy, physically active men.

Is this really the first study? Yes, it is the first to prove metformin's ergogenic effects in humans. It's yet not the first human study to test the ergogenic effects of metformin. 2008 Johnson et al. made the mistake to assume that taking metformin would affect the VO2max, or ventilatory threshold. Just like Gudat et al. before them, Johnson et al. simply missed the most straight forward practical measure of exercise performance, i.e. total time to exhaustion, while focusing on things like VO2 (Johnson et al. 2008) or lactate (Gudat et al. 1997) which are nice to explain increases in performance, but - if we are honest - still irrelevant, when all that really counts is how fast you run, how long you cycle or how hard you hit.

While many of the variables they assessed didn't change, the already hinted at 14% increase in maximal endurance (see headline) is something that may make the difference between winning an Olympic medal and placing fourth or worse.

Figure 2: Changes in time to exhaustion and EPOC, both stat. significantly w/ metformin (Learsi. 2015).

What is also noteworthy is that the subjects excess post-exercise energy consumption, which was measured for (unfortunately) only 10 min, increased significantly, as well (see Figure 2, right). In contrast to what some bro-scientists may tell you that does not necessarily equal increased fat loss, but it's still interesting, because it may suggest that metformin improved the subjects' performance by increasing the supply of energy via the anaerobic alactic system, i.e. by boosting the efficacy of non-glucose- and thus non-lactic-acid-dependent energy pathways - in short: fat oxidation.

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Bottom line: This is the first human study to confirm that the AMPK-booster and frequently prescribed diabetes drug can trigger statistically and practically relevant increases in endurance performance during a supra-maximal VO2 max test. If we assume that a similar performance increase occurs in trained athletes, the Learsi study makes taking a bunch of grandma's metformin pills before the next race quite attractive. For the WADA, however, it means that they will have to watch and test for yet another commonly prescribed and readily available medication. And last but not least, for the "wonder-drug" metformin, it is yet another area of application: athletic performance enhancement or as we usually call it "doping" | Comment on Facebook!

References:

• Gudat, U., G. Convent, and L. Heinemann. "Metformin and exercise: no additive effect on blood lactate levels in healthy volunteers." Diabetic medicine 14.2 (1997): 138-142.
• Johnson, S. T., et al. "Acute effect of metformin on exercise capacity in active males." Diabetes, Obesity and Metabolism 10.9 (2008): 747-754.
• Learsi, et al. "Metformin improves performance in high-intensity exercise, but not anaerobic capacity." in healthy male subjects." Clin Exp Pharmacol Physiol. 2015 Aug 7. doi: 10.1111/1440-1681.12474. [Epub ahead of print]