Making HIIT a Hit Part I/II: The Quest for the Optimal Interval to Rest Ratio for Your Type & Goals - Warming up: Selected Studies + Individual Take Home Messages to Set the Scene

This series will not readdress the "HIIT and/or LISS debate", but simply try to do what the title says: Help you to determine the "ideal" form of HIIT for your type & goals.

After posting yet another article about the benefits of high intensity interval training (HIIT) training on Wednesday, I thought it may be a good idea to take a look at the pertinent literature to get a better grasp of what exactly high intensity interval training actually is... "What it is? What do you mean?" While almost everyone appears to recommend you do at least some amount of high intensity interval training, these days, the definition of both the "high intensity" and the "intervals" which are more than just eponymous of this type of training are usually pretty wooly. The two questions this article is supposed to answer are therefore: How long should the intervals and rest periods be and at which intensity should they be performed.

Attention, this article turned into a two part series: I must warn you, this "quest" turned out to be hell lot of work and way more than I had expected. So I will have to split it up into a two-part series. With today's first part discussing exemplary "success stories" and the subsequent follow up on next Sunday providing a more comprehensive overview and general conclusions one may draw based on the picture that emerges.

Part I: Success stories - learning from the "best"

I decided that it may be a good idea to initially compile some examples of which you could say that they are examples of a successfully implementation of high intensity interval training. In that, I will put an emphasis on "old" studies that have not yet been discussed on the SuppVersity. This means, if you want more examples before next week's 2nd installment with a more general overview, you can simply click through the archive of articles that are marked with the keyword HIIT - either as HTML or RSS (I recommend the latter if you do not intend to read all of them anyway; opens in all good browsers without a reader).

Untrained participants and non-athletes

• 5min on, 2min off HIIT to increase fitness (VO2max) alternated with 40 min steady state cardio for 4 + 5 weeks (Hickson. 1981) -- Hard to believe but it's more than 30(!) years ago that Hickson, Hagberg and Ehsani were able to show that a combination of high intensity interval training with 6x5min cycling at 90-100% of the VO2max and 2-min at 30%-50% active rest between intervals on day one and 40 min of steady state "cardio" on a treadmill on day 2 (6 workouts per week) yielded profound increases in VO2max:
  

  

  Figure 1: Adaptation to combined HIIT + steady state protocol in "occasionally active" but not "regularly" trained men (n=8) and women (n=1) in the Hickson study (Hickson. 1982).

  For our purpose, the most significant finding of this study may however be that the t_1/2, i.e. the amount of time it takes for 50% of the adaptations to take place is only 10 days (on this intense protocol).
  
  Take home message: If VO2Max and overall conditioning is your goal you should up the intensity every three weeks, to make sure you continue to make progress. If you go by VO2max, this would be an increase in the speed you run or bike - not (!) the duration of the intervals and / or their number.

• 2 series of 5s sprint cycling (8-13x) with 55s of active rest increase force production and rids subjects of "useless" type IIb fibers (Linossier. 1993) -- The 10 students (8 men, 2 women; age 22y; VO2max = 51.2ml/kg/min, everything below 55 is still considered ) in the Linossier study performed 4 HIIT only workouts consisting of 5s all-out sprints on a cycle ergometer interspersed by 55s of active rest cycling at a heart rate of 130-140bpm per week. The number of sprints in each of the two sessions on a single training day (15 min of rest between) were increased from 8 to 13 sprints over the 7-week study period. The main results were improvements in both peak performances +25%  and in the 30-s total work +16%.
  
  

  

  Figure 2: Unexpected shift in muscle fiber type distribution (Linossier. 1993)

  What's also relevant, though not directly performance related is the 19% increase in phosphofructokinase and a 20% increase in lactate dehydrogenase, both are glycolytic enzymes and are indicative of improvements in the glycolytic pathway, which goes to show you that you don't have to be afraid of the fiber type changes hampering either your ability to handle glucose or your strength - I mean +29% in maximal force production in the sprint tests are everything else but "weak".
  
  Take home message: Shorter sprints appear to be a valid means to hammer and improve the glycolytic pathway and get rid of the useless type IIb fibers, of which not endurance athletes, but bodybuilders have the lowest amount and sedentary controls the most (cf. figure 1 in the overview of the Intermittent Thoughts on Building Muscle). To actually build muscle the 1% increase in muscle weight the scientists observed, is yet not sufficient enough.

• 7 sessions of 10x4 min cycling at 90% with 2 min rest ramp up skeletal muscle fat metabolism in young women (Talanian. 2006) -- The 8 healthy recreationally active women (22 yr old, 65.0 kg body wt) who had previously engaged in 2-3 just-for-fun sessions of various activities from weight lifting, soccer and cycling to swimming, or walking, participated in no more than 7 HIIT sessions within 2 weeks (1 day on, 1 day off) which consisted of 10x 4min sprints at 90% of their individual VO2max with two minutes of rest in between.
  
  

  

  Figure 3. Changes in substrate utilization during standardized 60 min LISS test at 60% of the VO2Max (Talanian. 2006)

  Contrary to the previously discussed studies, the scientists were in this case less interested in the performance than in the metabolic benefits, which were - as the data in figure 1 show - surprisingly significant given the short duration of the study. The increases in fat oxidation and decreases in the respiratory ratio (the ratio of glucose to fatty acid oxidation) during a standardized 60min light intensity (60% VO2max) test that was performed at the beginning and end of the study, were a consequence of increases in citrate synthase and beta-hydroxyacyl-CoA dehydrogenase (beta -HAD) activity.
  
  Take home message: In view of the important contribution of beta-HAD to the beta oxidation of (esp. medium-chain) fatty acids, the fact that an upregulation of this enzyme has been observed in response to the long duration intervals, but neither light intensitsy exercise (even w/ 2h per day, 5-6 times per week; cf. Phillipps. 1996), nor during a similar 2-week sprint training protocol (30s all-out on cycle ergometer, 4 min rest; cf. Burgomaster. 2005) points towards "long" duration intervals when mitochondrial adaptations that favor fatty oxidation and thus subsequent increases in fat loss with light activity are concerned. 

Highly trained participants and pro-athletes
 

• 3 sessions of 10 intervals at 96% VO2Max with 60-180s rest increase running economy and relative fatty oxidation during subsequent steady state exercise test (Zavorsky. 1998) -- Twelve highly trained endurance athletes volunteered for this study, four of them qualified for the 1996 Canadian Olympic Trials, and one subject was a Canadian record holder in triathlon. On three different occasions the subject ran 10 x 400-m sprints with active recovery periods of 60, 120, 180s (randomly assigned). 10 min before and afterwards standardized running economy tests were performed.
  
  

  

  Figure 4: Respiratory exchange ratio in RE test before and after the sprinting protocol (Zavorsky. 1998)

  During these running economy tests, which consisted of 2 x 5 min running on a treadmill at 12km/h or 16km/h (5 min total rest in between), the subjects exhibited, much contrary to the research hypothesis, by the way, an increase in the running economy (RE, a measure of how efficiently a person uses oxygen while running at a given pace) and - probably of greater interest for most of you an increase in fatty acid oxidation, as evidenced by the reduced respiratory exchange ratio (RER, figure 4). The latter was particularly pronounced in the "low intensity" RE test at 12km/h.
  
  As far as the differential effects of the rest intervals is concerned, significant effects were observed for the rates of perceived exertion (60s: 17.7; 120s: 16.1; 180s: 14.4), but not for the performance related measurements velocity, and the time it took the athletes to run the 400m sprints (actually the latter should be self-evident with identical velocities).
  
  Take home message: Doing ten short sprints (if you are not an athlete, shorter ones will suffice) before you go jogging (or do any other type of steady state cardio) won't hamper your running economy. And since the study at hand suggests that the relative increase in fatty acid oxidation is specifically pronounced in the lower intensities (this is supposedly even more the case if you jog at 10km/h), the combination of sprints + steady state cardio appears to be an ideal "cardio" only day, when you are trying to lose body fat.

• 8x all-out (100% VO2max) 2.5min intervals with 4 min of active rest increase VO2Max, peak aerobic power and 5k time trial performance regardless rest between sessions (Gross. 2007) -- With the unique twist with respect to the training frequency this study is somewhat unique. While other studies report similar benefits in highly trained collegiate cyclists (13 men, 4 women; VO2Max at baseline 62ml/kg/min) or other endurance athletes, this is one of the few that investigates whether it makes a difference if the athletes implement the 3-days per week HIIT regimen as a block or interspersed by one day of rest into their regimen.
  
  

  

  Percent change in TT5k velocitym TT5k power output VO2peak, and peak aerobic power output in cyclists trainin on consecutive vs. non-consecutive days (Gross. 2007)

  Interestingly enough, neither the performance outcome on the pre- and post tests, i.e. increases in VO2Max (+5.7%), peak aerobic power (+7.2%), 5k time trial performance (+6.9%), nor the actual performance during each of the workouts the subjects performed in the course of the 3-week study period suffered from doing the HIIT sessions back to back. These results refute previous speculations that doing HIIT as a block would trigger greater metabolic adaptations, specifically in athletes (e.g. Padilla. 2000). Even more, though the changes were not statistically significant, the data in figure 5 shows that - with one for endurance athletes important exception, namely the VO2Max - training on non-consecutive days produced marginally better results.
  
  Take home message: While it appears as if it would not make a difference whether you perform your HIIT workouts blocked or within your training week. The non-significant differences in figure 5 could suggest that endurance athletes intending to improve their already high VO2Max even further would be better off with the blocked training. Everybody else has the choice and I would pick the interspersed variety, whenever my schedule allows me to do this - my personal experience told me that this works better for me... apropos, take another look at figure 5 you see the narrow bars indicating the standard deviations? This goes to tell you that it is very likely that not just the personal preferences, but also the actual outcome will vary from trainee to trainee, which supports the notion that you will have to experiment to find what works best for you.

That's it for the "success stories"! Don't forget to come back next Sunday for part II and in case you have not done so already, just browse the previous SuppVersity posts on this matter, either as HTML version, post by post, or from the RSS overview (works in every modern browser, yet not in Google spyware ;-). I know you are smart enough to draw your own conclusions. And what's more, this may yield some cognitive input for the comment area of this article, where you can post questions. I will try to tackle those I can answer in the next installment.

References:

• Burgomaster KA, Hughes SC, Heigenhauser GJF, Bradwell SN, Gibala MJ. Six sessions of sprint interval training increase muscle oxidative potential and cycle endurance capacity in humans. J Appl Physiol. 2005; 98: 1985–1990.  
• Gross M, Swensen T, King D. Nonconsecutive- versus consecutive-day high-intensity interval training in cyclists. Med Sci Sports Exerc. 2007 Sep;39(9):1666-71.
• Hickson RC, Hagberg JM, Ehsani AA, et al. Time course of the adaptive responses of aerobic power and heart rate to training. Med Sci Sports Exerc 1981; 13: 17-20.
• Linossier MT, Denis C, Dormois D, Geyssant A, Lacour JR. Ergometric and metabolic adaptation to a 5-s sprint training programme. Eur J Appl Physiol Occup Physiol. 1993;67(5):408-14. 
• Padilla S, Mujika I, Orbañanos J, Angulo F. Exercise intensity during competition time trials in professional road cycling. Med Sci Sports Exerc. 2000 Apr;32(4):850-6.
• Phillips SM, Green HJ, Tarnopolsky MA, Heigenhauser GJ, Grant SM. Progressive effect of endurance training on metabolic adaptations in working skeletal muscle. Am J Physiol Endocrinol Metab. 1996: 270: E265– E272, 1996
• Talanian JL, Galloway SD, Heigenhauser GJ, Bonen A, Spriet LL. Two weeks of high-intensity aerobic interval training increases the capacity for fat oxidation during exercise in women. J Appl Physiol. 2007 Apr;102(4):1439-47. 
• Zavorsky GS, Montgomery DL, Pearsall DJ. Effect of intense interval workouts on running economy using three recovery durations. Eur J Appl Physiol. 1998; 77: 224-30.

Adelfo Cerame: My Fave 5 Intensity Techniques - Explode, Control the Negatives, Unleash the Neanderthal and Grow!

Most of you will be familiar with the structure of these posts, but for the newbies: While I (=Adel aka Dr. Andro) write the introductory paragraph, the actual post is nothing, but a "copy, paste and edit" job I do on the textfiles my friend Adelfo Cerame sends me each week.

Just a brief reminder to all of you, that ever since last week I am using Thursday, my free day, here at the Suppersity, or as Adelfo would say: The day "yours truly" is in command, here for a casual science chat with my friend Carl Lanore over at Super Human Radio. Now, that would probably not be worth mentioning, if it would be airing live on the Super Human Radio Network at 1PM EST ;-) So, in case you are interested in some details about the latest upheaval about organic vs. conventional foods. Want to learn why creatine is one of the supplements where performance enhancement is could as well be considered "yet another nice side effect", why you'd better tell your kids to lift some weight instead of ordering them to "clean their plate" and how what is and isn't on that plate may determine whether or not you and your kids develop cancer, I suggest you click here and listen live (link to the podcast will follow)... only after you have digested Adelfo Cerame's take on "intensity techniques", of course!

My Fave 5 Intensity Techniques

Intensity techniques are sort of a double-edged sword. Too often people get caught all up in the idea of "go heavy and go home" or "train until you drop" and lose sight of the what Adel, aka Dr. Andro, has once aptly called "out-training your regenerative capacities" (read more about overtraining and regeneration). More often than not trainees forget that the strength and size gains in short episodes of overreaching are bought on tick and the "interests" are high - so high, in fact that they often end up losing more than they have gained in the first place. Keep that in mind when you're incorporating one or another of the following "intensity techniques" (in the broader sense) in your workouts.

1. 

   I have been incorporating this technique within the past 3 weeks of 5/3/1 - see "5, 3, 1 for Wheelchair Bodybuilders"

   Explosive movements: I know what you think now - "I know those!" I must warn you though, what I call explosive movements might well be a bit different from what you are just contemplating. The average trainee associates "explosive" movement with exercises such as sprints, box jumps, clean & jerks, and squats ... I guess, I don't have to tell you that I can't to any of those. For me this meant that I had to find alternative exercises and the once I piced are
   
   • bench presses or heavy rows and
   • weighted dips or weighted chins
   I incorporate those move in my low volume phase (remember what I wrote before about "out-training your regenerative capacities!) - low volume, heavy load (3-5 rep range) + explosive lifts, that's  my success formula.
   With the heavy loads and the low(ish) volume, I can still focus on appropriate form on every set and every (!) rep. Even if you were similar Unbreakable as Bruce Willis in the same-titled movie, it would be nonsensical to sacrifice form and muscle tension for "speed" and turn a weight lifting workout into a weight throwing workout in no time. Try that, i.e. heavy weight +  fast contractions (not just weights flying from A to B) in the 10-12 rep range and you will realize that by the 6th rep or so, your form will go out the window.

2. 

   Negatives work best, when you lift heavy.

   Focusing on negative movements: In my opinion negative movements is where most of the magic happens, when it comes to putting your muscle under that productive strain that's necessary to signal your body that there is need for more: More muscle mass and more structural elements and subsequent resistance against strain.
   Remember: A rep has just begun, when you've managed to pull or push the weight up, down or in whichever direction you have been moving the weight against gravity - at this point, the most important part, the negative is just about to come!
   And this is even more true, when you apply intensity technique (1), i.e. you explode on the concentric part of the exercise and then g-o .... s-l-o-w ... on the negative ;-) 
3. Increase the pace of your workouts: Less rest and more action - that's the simple formula, here. It is however not always easy to increase the pace of your workout, but one way that I've found works for me is to copy some of the Dog Crap principles, i.e. taking twelve deep breaths as a "timer" for your rest times and then get on with your workouts.
   Increasing the pace is yet not only a physiological thing - it is in as much taxing, but also enormously stimulating to your psyche. It gives you that sense of urgency that will not just allow you to go faster, but also to push forward more vigorously. It keeps the heart pumping, the blood flowing, and the mind racing and that's exactly why you better not do it workout after workout, week after week if you don't want to end up overtaxing your sympathetic nervous system. 
   This technique works best during hypertrophy / high volume phases (or days if you are training on a hybrid training system, like my shoulder routine during the RTWC, for example)

4. 

   Supersets are best done on high volume/ hypertrophy- training days or if you’re cut short for time and want to decrease the time you spend in the gym without having to sacrifice the volume.

   Supersets: Doing exercises back to back, aka supersets, is one of the classic intensity techniques that has come to be one of my favorites, as of late. In my opinion supersets help stimulate those hard to target muscles. In my case it would be my chest area. As I mentioned in previous installments of this series, it’s hard for me to stimulate or feel a pump in my chest area - that's specifically ture, whe I am doing compound movements like a flat bench press, but if I do a set of ...
   
   • close (neutral) grip DB presses
   • before a set of BB presses
   I can really feel my chest being stimulated. In conjunction with the boost in workout density (i.e. the number of sets you perform within a given timeframe) you're actually killing two birds with one stone (or 2 workouts in 1 exercise ;-). 
5. Just move weight! This is what you do on those days, when you feel like a Neanderthal. Those days, when you just want to push, grunt and bang weight; ignoring the world around you and do nothing but lift! Usually, I stick to my plan, even on those days, but there are those rare occasions, when I just say:

   

   There are those days where you just have to follow your instinct and tear down the gym like in the good old days ;-)

   F#ck it! And to hell with the mind and muscle connection, negatives, focused reps or any other of your other techniques to how weights should be lifted. I just want to move weight!  – Fast, hard, heavy (a weight that you can bang all through your workout), but controlled.
   On those occasions I don't even count my reps; I just keep pushing and pulling, rest for a couple of seconds and head on to the next set. Same for the sets… sometimes I’ll do 3 to 4 but whenever, if I feel that the Neanderthal in me likes do to a few extra sets, I’ll do it… and then? On to the next exercise!
   This is a fun way for me to not think so much and just go with the flow as I go through my workout routine – and yes I still have an agenda of what body part I’m training and what exercises I will be doing but other than that, the only thing on my mind is moving weight! Simple as that!

Hey, where you heading? Oh, I see you are in Neanderthal mode right now? Ok, no problem. See you next Thursday, then ;-)

To Fail or Not to Fail - 5x10 or 10x5? The Energetic Demand of Your Workouts Doesn't Depend on Workloads, Alone

Image 1: PCr, ATP, whatever as long as there was energy left, Arnold kept pumping iron (pun intended ;-)

"To fail or not to fail", this question is probably about as ancient as the hilarious idea to engage in physical activity that is not in one way or another directly related to one of our two most fundamental needs, survival and procreation. Researchers from the Physical Education Department at the Sport Sciences University of the Basque Country and the Department of Health Sciences at the University of Navarra in Spain have recently examined this question from a slightly different angle than most of the articles you have probably seen in and on the various muscle mags and bodybuilding related websites on the Internet. What Esteban M. Gorostiaga and his colleagues wanted to know was:

Are There Significant Differences in Energy Metabolism When you Train to Failure?

Or, put another way: Does it make a difference if you fail from a molecular energetic point of view or is the mere number of reps the most fundamental determinant of the changes in muscle adenine nucleotides, inosine 59-monophosphate (IMP), phosphocreatine (PCr), creatine (Cr), lactate and energy charge during a workout. To answer this question the researchers recruited 6 healthy male volunteers (age 28-40y; BMI 23.3kg/m²; 1-RM_max on unilateral leg press 199+/-43kg) and had them perform a total of 50 repetitions with the same initial load (83% of 1-RM) on two separate occasions, either

• performed to failure, as a quintette of 5 x 10 (sets x reps), or
• stopped before failure, in a 10 x 5 fashion.

On both occasions the subjects rested 2 minutes between the sets. Furthermore, Gorostiaga et al. tried to eliminate "confounding factors", by equating the values of several variables such as initial load and total number of repetitions between both exercise sessions and making sure that whenever a "subjects could not lift the initial load during the following sets due to fatigue" the load was decreased by 15kg until the respective subject was able to complete all 50 repetitions (Gorostiaga. 2013).

Figure 1: Peak power output profiles (average for n=6 subjects) for each exercise during the two experimental conditions: when exercise was 5 sets of 10 repetitions to failure (10REP; open circles), and when exercise was 10 sets of 5 repetitions not to failure (5REP; filled circles; adapted from Gorostiaga. 2013)

It is plain to see from the data in figure 1 that performing all sets to failure (open circles) lead to a significant reduction in total workload (the area under the peak powder curve):

During 5REP all the subjects were able to complete all the repetitions with the initially load assigned (154+/-31 Kg; 83+/-8% of 1RM). During 10REP, however, most of the participants were unable to complete all the repetitions with this starting load, due to failure. The load had to be reduced by 7.2+/-3.8% after 27+/-16 repetitions and was progressively reduced, reaching 85+/-12%(P,0.05) of the initial load at the last repetition. Average load during the 50 repetitions of 10REP was 6.1+/-6.3% lower (P<0.05) than during 5REP. (Gorostiaga. 2013)

If we examine the graph further there are a couple of other interesting things to observe, though:

• the 2nd-3d rep was the one with the maximal power - so much about the value / validity of 1-RM maximum strength tests, then ;-)
• the power progressively declined from the 3rd rep on (35-45%) and that with an astonishing dip after the 5th rep - maybe because subjects are used to do 5 reps, so that this could also be a psychological factor
• while not training to failure with 10 sets of five reps allows to maintain almost identical average peak power on all sets, training to failure with 5 sets of 10 reps resulted in a net reduction of 33% from 812Watts on the first to 569 Watts on the last set
• the average peak power per set was accordingly 28% lower, when the participants trained to failure

What's the "energy charge"? The energy charge was calculated as the quotient of (ATP + 1/2 ADP)/(ATP + ADP + AMP) and does thus quantify the ratio of usable to used energy in the muscle samples.

Yet while the average mean power output changes paralleled those of peak power output in both experimental conditions, the opposite was the case for the aforementioned muscle metabolites - muscle adenine nucleotides, inosine 59-monophosphate (IMP), phosphocreatine (PCr), creatine (Cr), lactate and energy charge - the scientists measured by high-performance liquid chromatography from the muscle biopsies they had taken from the right legs of the subjects on each occasion.

Is light training an option, at all?

Very much in accordance with the subjective experience of many trainees, the data in figure 2 appears to confirm that working out to failure does induce muscular exhaustion, which manifests in the form of physically quantifiable changes in muscle metabolites in the training to failure group

• almost depleted PCr stores in the failure group (85% fall, P<0.05), and 
• reduced ATP (-21%), energy charge (-4%), and  
• reduced adenine nucleotides pool (-20%; ATP + ADP + AMP), in the presence of
• increased IMP (+8600%) and lactate (+1400%) levels

Which stand in stark contrast to the mediocre decrease in of phosphocreatine, the almost unchanged muscle ATP, IMP, energy charge and adenine nucleotide pool and comparatively marginal elevations in blood lactate in the 10 x 5 non-failure group.

Figure 2: Changes in ATP, ADP, AMP, phosphocreatine (PCr) inosine monophosphate (IMP) and lactate from pre to post workout in the 5 x 10 (failure) and the 10 x 5 (no failure) session (data calculated based on Gorostiaga. 2013)

As far as the correlation between these markers and the actual power output during the workout are concerned, the scientist say that they observed a ...

Figure 3: Relationship between muscle lactate concentrations and average peak power (from Gorostiaga. 2013).

• significant linear negative correlation (R²=0.59) was observed between the average changes in peak power output observed during the last two repetitions (expressed in percent of the initial two repetition values) and the decreases in ATP levels (expressed in percent of initial value).
• significant curvilinear negative correlation between the average peak power output changes observed during the last two repetitions of the first and last sets (expressed in percent of the initial two repetition values) and the corresponding levels of muscle lactate. 

From the curvilinear nature of this relationship (see figure 3) Gorostiaga et al. conclude that "when muscle lactate levels do not exceed the upper limit of 10–15 mmol/kg wet muscle, power output changes little from maximum values". The exact opposite is yet the case, when the lactate values exceed this critical upper value and the power output begins to decrease sharply.

Image 2: While training like a sissy will at best produce suboptimal results, maxing out on every set of every workout will work for max. 2-3 weeks until you will not just lose the gains you may have made but end up weaker and with less muscle in the hospital, when an injury or total burn-out forced you to finally see reason. Going to failure on one the last set of a selected exercise for each body group may be a way smarter, safer and more productive way. Combine that with planned 3-RM tests to gauge your strength progress and you should see some nice gains and can keep track of your strength gains without risking burn-out or injury and trust me this has little to do with being a sissy!

Implications: At first sight you may certainly argue that the study does not provide much novel information. If you do however compare the main results to common wisdom about various strength training regimen, the total depletion of the phosphocreatine stores in the "higher" rep group and the increase in IMP levels, of which Gorostiaga et al. rightly argue that they reflect the failure of ATP resynthesis to match ATP hydrolysis rates and eventually feed into the uric acid cycle (as reflected by the 19% increase in the failure group) put an emphasis on the often underestimated energetic and metabolic demand of training to failure. In this context, the pronounced loss of purines from the muscle, as it has also been observed by Hellsten et al. subsequent to profoundly lowered ATP levels in the course of a one-legged HIIT protocol on a cycle ergometer (Hellsten 1999), and the subsequent extraction of urate from the blood by the muscle to restore intramuscular urate levels (remember: urate acts as a free-radical scavenger during intense exercise; cf. Hellsten. 1997) may well be an overlooked factor, when it comes to assessing exercise recovery.

Still, while the former would suggest that you better avoid training to failure altogether and simply hit the gym for a "light" 10 x 5 workout everyday, the minor reduction in PCr (-15% vs. -80%) and the non-existent rise in plasma lactate and urate (no stress = no adaptation?) do indicate that frequent light training session will probably not result in the desired, or at least suboptimal muscular adaptations, which are the physiological bases for the strength and size gains, you are looking for (read all about "The Physiology of Building Muscle"). Moreover, the almost unchanged ATP/ADP ratio (see figure 3), which is the gauge by which AMPK works (cf. "Zoning in on AMPK"), could be the reason why many of the "sissy workout" studies report that strength training would not have the same / any beneficial effect on glucose tolerance, lipid levels and all the other standard parameters of metabolic health scientists usually measure in those trials.

Bottom line: While it is almost certain that you will out-train your own recovery potential by going to failure on every set of every workout, the results of this study put an emphasis on the fundamental difference between physical workloads and their immediate physiological effects (just a reminder, the workload, i.e. weight lifted x reps was identical for both groups). What we are still lacking to derive concrete reliable workout tips from data like this, though, are clear-cut mechanistic or at least probabilistic relationships between the short term effects of and the long-term adaptation to different workout regimen and their respective energetic demands... ah, and by the way, this goes for the incredible popular measurements of post-workout protein synthesis, as well. Until now, no-one can say how much predictive value temporary increases in fractional muscle protein synthesis actually have in terms of long(er) term muscle gains.

References:

• Gorostiaga EM, Navarro-Ame´zqueta I, Calbet JAL, Hellsten Y, Cusso R, et al. (2013) Energy Metabolism during Repeated Sets of Leg Press Exercise Leading to Failure or Not. PLoS ONE 7(7): e40621. 
• Hellsten Y, Tullson PC, Richter EA, Bangsbo J. Oxidation of urate in human skeletal muscle during exercise. Free Radic Biol Med. 1997;22(1-2):169-74.
• Hellsten Y, Sjodin B, Richter EA, Bangsbo J (1998) Urate uptake and lowered ATP levels in human muscle after high-intensity intermittent exercise.Am J Physiol 274: E600–E606.

Are You Still Burning Calories or Already Losing Fat? Study Shows: 5x15 Min HIIT Reduce Body Fat & Improve Fitness Twice as Effectively as 5x40min of Classic Cardio

Image 1: The number of women striving to be strong & sexy is still too skinny.

Despite the fact that the slogan "strong is the new sexy" has become increasingly popular, as of late, my personal experience tells me that women are particular resistant to suggestions, let alone well-meant advice to drop "classic cardio" training all-together. Against that background the data from a study that has been published in the latest issue of the Journal of Sports Medicine and Physical Fitness, as convincing as it may be, is probably no more than another drop in the bucket, but hey... if there is only one women who's mental bucket is already chock-full it may be the one drop that will eventually make it spill over ;-)

"But didn't they lose more weight with classic cardio!"

What happens if you take 60 female overweight (BMI>25kg/m² and body fat >30%) university students and tell them they got to lose weight? Well, I guess, 45 will run to the next best newsdealer get their Shape, let alone Cosmopolitan and start starving themselves according to the latest diet fat from Hollywood, while the remainder will do just the same, except that they combine the starving with some "healthy" cardiovascular exercise in the mythical "fat burning zone". Now the former, i.e. the starvation diet, was not an option for any of the 60 Chinese women, as the design of the 12-week trial required them to maintain their regular diets, the latter, and even the walking or running in the "fat burning zone" was not really part of the experimental conditions the women were randomly assigned to:

• moderate intensity continuous training (MICT): 40min of jogging or walking at 50% of the individual VO2max 
• high intensity interval training (HIIT): 5x3min of running at 85%VO2max with 3min of active rest between the high intensity bouts
• sedentary control: no exercise at all

The exercise was performed on an outdoor track five times a week for a total of 12 weeks an elicited (remember: in the absence of any dietary interventions or restrictions!) pretty astonishing results in - and this must be said for the sake of fairness - both groups.

Figure 1: Changes in body composition and fitness parameters compared to baseline (Sijie. 2013)

If you take a closer look at the data in figure 1 it is yet evident that the 15min of HIIT exercise were not only less time-consuming, they also produced more pronounced and, what's even more important, more favorable changes in body composition, i.e. a greater reduction body fat percentage and waist-to-hip ratio, greater retention in lean mass (as evident from more pronounced fat loss in the presence of slightly lower reductions in BMI) and statistically significantly more pronounced improvements in cardiovascular fitness (VO2Max and ventilatory threshold) - exactly those domains, which should (but have never been) the domain of "cardiovascular" exercise ;-)

Not just for Chinese overweight women: Another recently published study by Astorino et al. confirms that the HIIT induced beneficial effects on VO2max are not restricted to otherwise sedentary, obese subjects, but will also occur in active, young men and women (age and body fat = 25.3 ± 4.5 years and 14.3 ± 6.4%). And that despite the fact that the subjects in the Astorino study performed only two sessions per week (4-6x 30s wingate tests = all out cycling followed by 5min active recovery) and the total duration of the study was no longer than three weeks (Astorino. 2013). In this context it is also worth mentioning that Ciolac et al. were able to show that young women with high familial risk for hypertension also derive greater benefits in terms of cardiovascular health improvements from aerobic interval vs. classic aerobic training (Ciolac. 2011).

Lose weight or lose fat? Look sick or look good? Burn calories or burn body fat? LISS or HIIT?

Despite all obvious limitations of this study it should thus be obvious that "cardio", regardless of whether you do it to improve your physique or overall fitness, must neither be time consuming nor should it be conducted in the "fat burning zone". Those of you who have been following the Step By Step Guide to Your Own Workout (specifically the Fat Loss Example Routine), will yet be aware that this does not imply that you must never perform "classic" low intensity steady state cardio. As a means of recreational activity on your off days, 20-30 minutes on a treadmill may actually help you recover from the "real" training sessions which will bring about those adaptation (fat loss and muscle gain) even women should be striving for if their focus is to improve the way they look and feel about their bodies.

A note on the right type of HIIT for you: If you compare the HIIT protocol in the Astorino to the HIIT protocol in the Sije study, it is pretty obvious that we are dealing with an all-out short burst approach (Astorino) vs. an high intensity longer burst approach (Sijie). In order to find the right HIIT protocol for you, you will have to reconsider your current training status and goals - with the general rule being: The fitter you are the more you should tend towards the shorter all-out bursts, because here, outside your comfort zone, is where the magic of adaptation happens. The more body fat you are still carrying, the more you should tend to longer high intensity bouts.

References:

1. Astorino TA, Allen RP, Roberson DW, Jurancich M. Effect of high-intensity interval training on cardiovascular function, VO2max, and muscular force. J Strength Cond Res. 2013 Jan;26(1):138-45
2. Ciolac EG, Bocchi EA, Greve JM, Guimarães GV. Heart rate response to exercise  and cardiorespiratory fitness of young women at high familial risk for hypertension: effects of interval vs continuous training. Eur J Cardiovasc Prev Rehabil. 2011 Dec;18(6):824-30. Epub 2011 Feb 28.
3. Sijie T, Hainai Y, Fengying Y, Jianxiong W. High intensity interval exercise training in overweight young women. J Sports Med Phys Fitness. 2013 Jun;52(3):255-62.

Saturated Fat & Postprandial Endotoxemia. Caffeine & Max. vs. Submaximal Exercise. Lactoferrin & the Battle Against Visceral Obesity. High Intensity Strength Training, Free Testosterone & the Use of Perceived Recovery Scales

Gram negative bacteria, as these E. coli bacteria which have been photographed with a low-temperature electron micrograph (magn. x10,000) tend to produce endotoxins in your gut, while gram positive bacteria tend to produce exotoxins on your food - nasty, ha?

It has been estimated that a single cell of Escherichia coli contains approximately 106 Lipid A or endotoxin molecules with a mass of about 100,000 Da (the exact mass varies according to the LPS type). The typical human intestinal tract can harbor approximately one gram of endotoxin, which is ~2-4x more than what scientists used in previous rodent studies as a "lethal dose" (Kawai. 1991). Aside from the information about the lethal dose of endotoxins in rodents, these figures, which are at the same time the SuppVersity figures of the week are part of the study by Mani et al. with which we are going to kick off this week's installment of On Short Notice. I guess these figures give you an idea of the toxic potential within your gut and why all the hoopla about leaky guts, the human microbiome, pro- and prebiotics, endotoxemia and co. is probably not all hype, but a hitherto largely neglected aspect of human health (and disease)

Saturated fat < > gut interaction sheds a dark shadow on the "benign fat of our ancestors"

(Mani. 2013) -- According to a study from the University of Iowa, the endotoxemia response to a meal, i.e. the amount of inflammatory innately produced toxins from your gut that enter circulation in the postprandial phase, is increased in response to a meal that's high in saturated fat.

Figure 1: Endotoxin permeablity and changes in serum endotoxin levels in the hours subsequent to the ingestion of a test meal containing either 50ml  coconut (CO), vegetable (VO) and fish oil (FO) in otherwise healthy pigs (Mani. 2013).

The scientists also found that omega-3 fatty acids from fish and cod liver oil reduced the amount of endotoxins hitting the blood stream and that olive, as well as vegetable oils exhibited a neutral effect. As the data in figure 1 (left) goes to show you, the underlying mechanism behind the saturated fat induced influx of toxins was a whopping +60% increase in the endotoxin permeability (Papp) of the guts of the 24 pigs on which the experiments have been conducted.

Click here to read more about a previous study that shed some light on the effects of certain nutrients on the gut microbiome.

Now you can certainly argue that the ground corn-soybean meal dough that was at the base of the test-meal was "the devil" here, but let's be honest, for the average Jane and Joe, there are similar "devils" in any standard meal, they consume, so that the finding that the addition of 50 ml fish oil (FO), vegetable oil (VO) or coconut oil (CO) made such a difference in terms of the influx of pro-inflammatory endotoxins is nothing you can simply ignore. The same goes for the fact these effects occurred in response to the ingestion of organic coconut oil (according to the researchers purchased from Spectrum Naturals Inc.), is actually somewhat unsettling and certainly not in line with some of the previously established benefits of coconut oil consumption, such as it's waist reducing effects in overweight subjects (click here to learn more).

What's also interesting is that previous rodent studies yielded different results. Laugerette et al., for example, found a similar increase as Mani et al. in mice, but in response to canola and sunflower oil (Laugerette. 2013). This raises the question in how far the effects may be mediated by the baseline diet and the corresponding bacterial composition of the small and large intestine (or species specific effects?). After all, the gram negative bacteria of which scientists believe that they increase in response to high fat diets have the highest endotoxin content. They populate the distal ileum and the colon and are supposedly the main sources for circulating endotoxin (Berg. 1999) - if you had less of them to begin with, you are not as likely to suffer from an acute influx of endotoxins in response to the ingestion of SFAs. Moreover, what it the endotoxins were released in response to the antimicrobial effects of coconut oil?

Update: Wyatt Brown left an interesting comment on this issue on the SuppVersity facebook wall, I do not want to deny anyone, so I thought I'd just update the post with it:

I'm glad people are talking about the endotoxemia thing, that's what we do at SuppVersity, have the discussions nobody else does! I think it's important to recognize that, especially for the paleo/ancestral types who accuse grains of inducing intestinal permeability and then go and eat diets that cause intestinal permeability...and because endotoxemia is bad...

But I don't think that all is lost, the evolutionary argument may just need to be modified a little. The current paradigm involves looking at individual foods, or worse yet (though that was supposed to be an improvement) broad classes of macronutrients, and our adaptation to them. Well, it looks like those might have been wrong in some ways, maybe we aren't fully adapted to some foods, but then again maybe we are adapted to a particular kind of diet that makes those foods all right.

Some of the antioxidants in orange juice prevent intestinal permeability from dietary fats it seems the bile acids secreted during digestion are to blame, and it's an oxidative mechanism, so the orange juice prevents this (Ghanim. 2010). It also works with grape polyphenols (Ghanim. 2011).

Moreover, it seems that feeding mice a diet rich in fermentable fibers prevents endotoxemia - maybe due to butyrate production and its protective effects on intestinal cells (Cani. 2007). And acutely, fiber with a high fat meal also prevents the effect (Ghanim. 2013). It's probably due its ability to sequester excess bile acids (Vahouny. 1980)

So it would appear that we are adapted to a diet containing those fats but also containing fruit and fiber.

As you see, Wyatt makes a pretty valid point, when he hints at other contributing factors of which I know that they got forgotten way too often in the paradigmatic and downright stupid and unproductive high fat vs. low fat and the SFA vs. PUFA skirmishes on the Internet.

I guess, there is still much to learn here and I hope you are aware that the SuppVersity is the place you can do just that: Learn something new everyday!

Caffeine's effect on muscular fatigability during maximal vs. supramaximal stimulation

There is no question that caffeine can have beneficial effects on exercise performance - whether every athlete benefits to a similar degree is yet as questionable as the "ideal" dosage to elicit optimal fat loss effects without the negative side effects that are associated with the chronic overconsumption of any type of stimulant (click here to learn more about the narrow margin between "just enough" and "already too much")

(Tallis. 2013) -- In a very straight forward in vitro experiment, researchers from the Coventry University in the UK found that the ergogenic effects of caffeine depend on the intensity of the muscular contractions. When the scientists exposed isolated soleus muscles to up to 70µM of caffeine (that's still within what you would consider a "physiological dosis"), Tallis et al. observed that the muscular endurance increased only, when the muscles were challenged at submaximal intensities (+19.2%), while it decreased by 17.6% upon maximal challenge.

Whether or not this is important for the average strength trainee remains questionable. After all the "endurance" part of your regimen is usually conducted at submaximal intensities and weheter you can do one interval more or less probably doesn't matter as well. For a professional cyclist participating in a time trial, those 17.6% may well make the difference between victory and defeat. On the other hand, there is more to "endurance" than local muscular fatique, so that caffeines effects on the central nervous system will at least ameliorate, if not totally counter these potential downsides.

Lactoferrin, an overlooked visceral fat annihilator?

I don't even know if all of you are familiar with the globular glycoprotein lactoferrin that is widely represented in various secretory fluids, saliva, tears, nasal secretions and - above all - colostrum. It has a very important role in the immune defenses of your body and according to a recent review by Japanese scientists, it does also exert direct lipolytic (breakdown and release of fat from) and anti-adipogenic effects in vitro and in vivo.

All of you who read the "Ask Dr. Andro" installment on Milk & Colostrum should at least have heard of lactoferrin before. It's one of the anti-microbial, anti-fungal and immune modulating molecules in the white elixir of mammalian life that's also suppose to exert antagonist effects on the opioid receptors (read more).

A hitherto still unsolved problem is the delivery of the lactoferrin to the target tissue, but with the advent of specifically enteric coated lactoferrin which circumvents the breakdown of the 80kDa protein in the acidic milieu of the stomach and allows its passage via the lymphatic system into the mesenteric (visceral) fat pad, where it accumulates, interacts with the lactoferrin receptor LRP1 which is directly located on the adipocytes of the visceral adipocytes and suppresses the expression of PPARγ reduces the expression of perilipin and thus shuts down lipogenesis and increases lipolysis in existing adipocytes. Accordingly, respective supplements could in fact become "a highly safe and a promising dietary supplement" that has in addition to its already well-known beneficial effects on the immune system the ability the potential to "be used to promote human health globally" (Ono. 2013). But let's be honest, haven't we heard claims like that before?

Perceived recovery 48h after a workout correlates with free testosterone levels

(Sikorski. 2013) -- Yeah, I know the whole free testosterone after a workout discussion is pathetic, but what about free testosterone levels 48h hours after the workout, i.e. amidst the hot recovery phase? According to a soon to be published study in the Journal of Strength and Conditioning Research a standardized test to elicit the perceived recovery (PRS) appears to be surprisingly accurate to predict the drop in free testosterone after a session of high volume resistance training designed to elicit a large amount of fatigue and muscle damage. 

"All subjects participated in a high volume resistance training session consisting of 3 sets of 10-12 repetition maximum loads for each of the following exercises: full squats, bench press, deadlifts, pullups, bent over rows, dips, shoulder press, barbell curls and triceps extensions. Rest periods were 1 minute between sets, and 2 minutes between exercises." (Sikorski. 2013)

The scientists from the University of Tampa recruited 35 highly resistance-trained subjects (aged 21.3 ± 1.9 years) with an average squat, bench press, and deadlift of 1.7± 0.2, 1.38 ± 1.9 and 2.07 ± 2.7 times their bodyweight for their study. The subjects had a minimum experience of 3 years of resistance training and were thus probably way more capable to access their own recovery status than the average Jane or Joe after with a dozen of irregular workouts under her / his belt. Blood analyses, soreness and PRS tests were conducted at before, immediately after and 48h after the workout (total weight lifted in the training session was 16,353 ± 3,691.8 kg) and revealed ...

Read more about the hormonal effects of different workout styles in this previous SuppVersity post

• a significant increases in leg, chest and arm soreness from pre to post exercise,
• a significant increases in creatine kinase (CK; measure of muscle damage) from 189.4 ± 100.2 to 512 ± 222.7 U/L (p < 0.05),
• no changes in cortisol, testosterone, and free testosterone from pre to immediately post workout,
• a significant moderate, and inverse relationship between leg soreness and PRS scores and  low, inverse relationships between chest and arm soreness and PRS scores, 
• a significant, moderate inverse relationship between CK and PRS 

yet only when the CK values peaked 48h after the workout, however, the aforementioned "low, direct relationship with PRS" (Sikorski. 2013) was observed. As the researchers point out this result could be

"[...] important for those individuals that have neither the resources (time, monetary or otherwise) nor the expertise to draw blood and perform chemical assays to determine recovery status and or muscle damage. [...] This, in the bigger picture, may help appropriately design periodization plans designed aimed at functional overreaching and ensure proper overload. Moreover, and perhaps more importantly, the ability to indicate level of recovery following heavy resistance training expeditiously and accurately may be a critically important step in prevention of overtraining." (Sikorski. 2013)

The scientists do yet also emphasize that "future work is needed addressing other variable influencing recovery and long-term studies investigating the usefulness of the PRS in training" before a more general recommendation can be issued.

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That's it for today folks. As usual there are a couple of interesting facebook posts for you to check out and discuss

• Upping your vitamin D levels does nothing to reduce knee pain or cartilage loss in patients with symptomatic knee ostearthritis (read more)
• "The one-two punch", retinoic acid suppresses obesity by both promoting energy expenditure and by inhibiting adipogenesis (read more)
• More evidence of intrauterine dietary priming: Low protein in the womb + high caloric diet afterwards => insulin resistance (read more)

and obviously, you are invited to post your thoughts or questions on any of today's items in the comment area of this post.Aside from that, I wish all of you an exciting weekend ;-)

References:

• Berg RD. Bacterial translocation from the gastrointestinal tract. Adv Exp Med Biol 1999, 473:11–30. 
• Cani PD, Neyrinck AM, Fava F, Knauf C, Burcelin RG, Tuohy KM, Gibson GR, Delzenne NM. Selective increases of bifidobacteria in gut microflora improve high-fat-diet-induced diabetes in mice through a mechanism associated with endotoxaemia. Diabetologia. 2007 Nov;50(11):2374-83.
• Ghanim H, Sia CL, Upadhyay M, Korzeniewski K, Viswanathan P, Abuaysheh S, Mohanty P, Dandona P. Orange juice neutralizes the proinflammatory effect of a high-fat, high-carbohydrate meal and prevents endotoxin increase and Toll-like receptor expression. Am J Clin Nutr. 2010 Apr;91(4):940-9.
• Ghanim H, Sia CL, Korzeniewski K, Lohano T, Abuaysheh S, Marumganti A, Chaudhuri A, Dandona P. A resveratrol and polyphenol preparation suppresses oxidative and inflammatory stress response to a high-fat, high-carbohydrate meal. J Clin Endocrinol Metab. 2011 May;96(5):1409-14.
• Ghanim et al. The Intake of Fiber Suppresses the High-Fat High-Carbohydrate Meal-Induced Endotoxemia, Oxidative Stress and Inflammation. Endocr Rev, Vol. 33 (03_MeetingAbstracts): OR03-1
• Kawai Y, Kaneda K, Morisawa Y, Akagawa K. Protection of mice from lethal endotoxemia by use of an ornithine-containing lipid or a serine-containing lipid. Infect Immun. 1991 Aug;59(8):2560-6. Erratum in: Infect Immun 1992 Jan;60(1):320.
• Laugerette F, Furet JP, Debard C, Daira P, Loizon E, Geloen A, Soulage CO, Simonet C, Lefils-Lacourtablaise J, Bernoud-Hubac N. Oil composition of high-fat diet affects metabolic inflammation differently in connection with endotoxin receptors in mice. Am J Physiol Endocrinol Metab. 2013;302:E374–386.
• Mani V, Hollis JH, Gabler NK. Dietary oil composition differentially modulates intestinal endotoxin transport and postprandial endotoxemia. Nutrition & Metabolism. 2013;10(6).
• Ono T, Morishita S, Murakoshi M. Novel  function of bovine lactoferin in lipid metabolism: Visceral fat reduction by enteric-coated lactoferrin. Pharma Nutrition. 2013 [accepted manuscript] 
• Sikorski EM, Wilson JM, Lowery RP, Joy JM, Laurant CM, M-C Wilson S, Hesson D,
  Naimo MA, Averbuch B, Gilchrist P. Changes in Perceived Recovery Status Scale
  Following High Volume, Muscle Damaging Resistance Exercise. J Strength Cond Res.
  2013 Jan 2. [Epub ahead of print]
• Tallis J, James RS, Cox VM, Duncan MJ. The effect of a physiological concentration of caffeine on the endurance of maximally and submaximally stimulated mouse soleus muscle. J Physiol Sci. 2013 Jan 6.
• Vahouny GV, Tombes R, Cassidy MM, Kritchevsky D, Gallo LL. Dietary fibers: V. Binding of bile salts, phospholipids and cholesterol from mixed micelles by bile acid sequestrants and dietary fibers. Lipids. 1980 Dec;15(12):1012-8.