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.

The Iranian HIIT Solution: Three 200m Sprint Sessions per Week Double Insulin Sensitivity & Normalize Leptin Levels

Image 1 (iransportspress): Maryam Tousi Iran's first female Iranian athlete to compete in the IAAF World Championships in South Korea in 2011 was certainly not one of the 30 overweight study participants.

You will certainly remember the HIIT training video study, I mentioned in last Saturday's installment of the On Short Notice series, right (cf. "Insanity vs. TurboFire")? Now, despite the fact that at least some women seem to prefer hopping around like crazy with a bunch of other crazy "bunnies" in a gym and I will always stick to the recommendation that you will have to pick a type of exercise you actually enjoy doing in order not to fall off the wagon, when the initial success begins to slow down, a recently published study from the Islamic Azad University in Tehran, Iran, clearly suggest that "cheerleading" is not the only way and probably not even the most effective way to HIIT your metabolic syndrome with full intensity.

The Iranian success formula: 12 weeks, constant progression, 1,600 - 3,200m, thrice weekly

Sohaily Shahram and her colleagues from the Department of Physical Education and Sport Science at the University of Teheran handpicked  30 female overweight volunteer students from the university campus, who did not have any confounding health issues aside from their weight and ensuing metabolic problems and randomly assigned 15 of them to the HIIT exercise group.

Figure 1: Outline of progressive HIIT protocol that was used in the Shahram study (based on Shahram. 2013)

While the subjects in the control group did do nothing but continue on their regular, lazy lifestyle, the young women in the HIIT group performed the above HIIT sprint workout (cf figure 1) three times per week, with a work to rest ratio of 1:3 and a 10min warm-up (incl. light stretching) + 5 min cool down.

Would you really prefer taking medication and keeping your insulin sensitivity from further deteriorating over 21-42min of sprinting per week to increase your insulin sensitivity by 100%?

If we assume for simplicity that the women needed ~45s for the 200m (average for 8th graders is ~25-27s, but we don't want rise the bar too high, do we ;-) this would yield a total workout time (including warm up and cool-down) of 39-63min, increasing from week 1 to week 12, respectively.

Figure 2: BMI, body fat percentage, VO2Max (marker for cardiorespiratory fitness), insulin, glucose and leptin levels, as well as insulin resistance index  (calculated via HOMA model) after 12-weeks on the HIIT protocol from figure 1; data expressed relative to baseline (calculated based on Sharam. 2013)

If you take a look at the results in figure 2, you will obviously see right away that those two to three hours on the track per week had an immensely beneficial effect on the overall metabolic health of the subjects, who were, just as their sedentary peers advised to follow their "regular eating habits" over the course of the 12-week intervention.

Obesity and the Westernization of the East

Image 2: According to Esteghamati et al. the risk to become obese has increased from 13.6% to 22.3% for normal weight and from 32.2% to 36.3% from 1999 - 2007, alone (Esteghamati.2010). Yet despite the rise in overall and childhood obesity, Iran is still the country with the slimmest children (14%) in the Middle East, where Bahrain is the inglorious  leader with childhood obesity rates of 35% among the girls and 21% among the boys (Mirmiran. 2010)

Against that background it is not unusual and by no means lamentable that their weight stabilized (which probably is what not so educated physical culturists as you are would immediately have complained about). Rather than making a fuss about the minor loss of body weight (-2.29kg on average), the women should rather celebrate that they lost a total of 2% body fat (equiv. to a -9% reduction in body fat percentage, see figure 2) and primed their bodies to actually be able and willing to lose fat in the future by

• improving their aerobic workout capacity by 26% and thus lying the foundation for more intense fat loss workouts on a future diet
• improving their glucose metabolism and reducing their insulin resistance by >50% and thus being able to fuel their future workouts with the necessary amount of carbohydrates without totally negating their weight loss efforts while dieting

The one thing that would be missing now was a ~20% reduction in caloric intake and a switch away from energetically dense convenient and fast food, which has lead to a drastic incline in obesity in Iran over the last two decades (see caption of image 2) and towards a healthier more "oriental diet". The latter is, just like the infamous "Mediterranean diet", which has countless times being mislabeled as a "low fat diet", particularly rich in MUFAs (oils with 70%+ MUFA content: olive oil, macadamia oil, avocado oil) - and as you are going to learn in tomorrow's installment of On Short Notice these monounsaturated fatty acids have only recently been shown to be just as, if not more effective in keeping diet induced weight gain in check via their epigenetic effects on the expression of the growth hormone stimulating "hunger hormone" ghrelin as fish oils (Saidpour. 2013).

A word of caution The 16 x 200m variety of these HIIT workouts is nothing you'd perform after a strength workout. These workouts are about as taxing a leg workout and will require their own training day. If your current routine has three ore more strength days, don't do more than one of the long HIIT workouts per week. Depending on your goals you can incorporate max. 8x200m sprints after shorter workouts, or do HIIT (8x200m) in the AM and weights in the PM. Check out the Step By Step to Your Own Workout Guide to learn how set up your own workout routine and how to combine weights, HIIT & LISS.

Implications: Aside from the protocol, itself, which is unquestionably equally (I'd say even more) suitable for advanced trainees (women and men), the Shahram study has two major take home messages:

• Change and challenge have more in common than the initial three letters - If you don't challenge your body you cannot expect change to happen; just like your muscles won't grow if you always train with the same weight, HIIT workouts at least when are they supposed to increase your cardiorespiratory fitness need progression (the HRMax programing will automatize that, as you will simply have to work out harder to get your heart rate up, when your fitness has improved)
• Workouts prime your metabolism for fat loss, diets pull the trigger - If you have been lying on the couch for the last two or three years, your body will change even without any dietary intervention, but to really transform your physique you must make appropriate changes to your diet.

I guess, you could say that it's funny how many scientists (and certain science writers), usually with a bias to one or the other, still propagate that diet and exercise would be different means to one and the same end, if their messages would not lead millions of "dieters" and "1h-per-day-on-the-treadmill-walkers" into disaster ... you see, on their own, both can in fact become means to the same disastrous end.

Image 3: Leave the cheerleading to the boys, ladies and HIIT it hard! Fast paced and glycolytic sports will reduce / minimize your need to "diet" and help to avoid the dreaded YoYo Effect

Can you lose weight by simply eating less? Yes, you can. Can you lose weight by working out like a mad(wo-)man? Yes you can! ... but did you even notice that the word "lose" was in each of this questions? You don't want to join the Biggest Losers, do you? So lets start with a better question, then!

Can you improve your health, extend your life and look like a cover model? Yes, you can! All you got to do is build your success on both, not just one pillar of physical culture: Diet and exercise, exercise and diet!

So what are you waiting for? All you'll need is your daily dose of SuppVersity news and a pair of running shoes!

And eventually, even the shoes are obsolete. If you sprint on the beach you will get a greater training effect, anyways: Binnie et al. report 4% faster 3-km running times, when subjects performed their conditioning workouts on the beach (Binnie. 2013)

References:

• Binnie MJ, Peeling P, Pinnington H, Landers G, Dawson B. Effect of training surface on acute physiological responses following interval training. J Strength Cond Res. 2013 Jun 26.
• Esteghamati A, Khalilzadeh O, Mohammad K, Meysamie A, Rashidi A, Kamgar M, Abbasi M, Asgari F, Haghazali M. Metabolic Syndrome and Related Disorders. June 2010, 8(3): 209-213. 
• Mirmiran P, Sherafat-Kazemzadeh R, Jalali-Farahani S, Azizi F. Childhood obesity in the Middle East: a review. East Mediterr Health J. 2010 Sep;16(9):1009-17. Review. 
• Saidpour A, Kimiagar M, Zahediasl S, Ghasemi A, Vafa M, Abadi A, Daneshpour M, Zarkesh M. The modifying effects of fish oil on fasting ghrelin mRNA expression in weaned rats. Gene. 2013 Jul 25.
• Shahram S, Elham Y, Heshmatolah P, Abdolali Baneifar. The effect of intermittent aerobic exercise on serum leptin and insulin resistance index in overweight female students.Annals of Biological Research, 2013, 3 (6):2636-2641

A Double Dose of HIIT vs. Aerobics. Hazelnuts, Mushrooms, Strawberries = Polyphenol Laden Superfoods With Prebiotic, Anti-Cancer & Anti-Diabesity Effects. Plus: Backdoor to DHT

Actually the first post in today's installment of On Short Notice is a direct continuation of the SuppVersity Exercise Science Week with an intriguing novel contribution to the never-ending steady state vs. HIIT debate by scientists from the University of Birmingham (UK)

Hypothyroidism kills and therefore the SuppVersity Figure of the Week comes from a study on the effect of hypothyroidism on all-cause mortality from Denmark (Thvilum. 2013). The respective data comes from an observational cohort study and spans the years between January 1, 1978 and December 31, 2008. With an increased risk of  +52% (after stratification for the figure dropped to "only" +21%)  in the 3587 singletons, +61% in dizygotic twin pairs, but only +7% in monogyzotic twins, it's yet not quite clear, whether it's the being hypothyroid or rather having the disposition of developing respective problems is actually associated with an increased mortality. After all, you would expect similarly high levels in monogyzotic twins as in the rest of the population, if it was "only" about having a high TSH, which still is the only "official" accepted marker of clinical hypothyroidism.

Day 4 of the Exercise Science Week - A Double Dose of HIIT vs. Steady State Aerobics

(Cocks. 2013 & Shephard. 2013) -- If you ignored the titles and just read the first part of the methodological section it seems as if the two studies that were subsequently published in The Journal of Physiology late in 2013 were identical. What's identical, though is just the data set the two papers by scientists from the University of Birmingham are based on. The latter was acquired during a six-week experiment in the course of which 16 previously sedentary young men (BMI ~23kg/m²; age 21.5y) were randomized to a

• 

  34% increase in time to exhaustion, +91% increase in total work & exponentiated lean mass gains in response to HIIT + NAHCO3 (read more)

  classic steady state endurance training regimen - subjects cycled at workloads equivalent to ∼65% of their pre-established VO2peak for 40min in the first 2weeks, increasing to50min in the following 2 weeks, and 60min in the final 2 weeks; their obviously improved VO2peak was reassessed after 3weeks of training and workload adjusted accordingly

• sprint interval training  - subjects performed 30s "all out" (Wingate test) on a cycle ergometer using a load equivalent to 0.075kg per kg of body weight; each of the Wingate tests was followed by a period of 4.5 min of recoery (at 30W; <50rpm); the number of sprints increased from 4 to 6 sprints with one additional sprint every 2 weeks

As the scientists point out, all participants trained three (SIT) respectively five (ET) times a week for 6 weeks, and were excluded from the study if they were absent from more than two (SIT), respectively three (ET) sessions.

Figure 1: Overview of the relative changes of selected outcome variables measured in the "two" studies
(Cocks. 2013; Shephard. 2013)

While Cocks et al. analyzed the microvascular density and eNOS content of the muscles, the Shephard study, which was published a couple of weeks later, took a closer look at markers of intramuscular triglyceride breakdown and the expression of the anti-lipolytic lipid droplet-associated proteins perilipin 2 and 5. In previous studies, the researchers had observed that these proteins which are believed to protect the lipid droplets in adipose tissue from the "fat dissolving" lipase enzymes, appear to have a very different effect in the musculature, where PLIN2 and especially PLIN5 seem to act as key regulators of intra-muscular lipolysis and triglyceride breakdown (Shephard. 2013).

More similarities than differences?!

Figure 2: Selected parameters of body composition and blood glucose metabolism expressed relative to pre-exercise levels. (Shephard. 2013)

If we take a look at the outcomes of the studies (see figure 1, figure 2), it's not difficult to see that despite minor differences, most of the measured parameters in the Shephard study the observed differences, such as an increase of 7% in VO2Peak in the SIT vs. 15% in the ET group did not reach statistical significance. The same is true for the effect on the mitochondrial density, the insulin sensitivity, the maximal power WMax and the changes in body composition (see figure 2). Only the respiratory exchange ratio (RER), i.e. the ratio of carbohydrates to fats that were used during a 60-min endurance regimen at 65% of the VO2Peak, changed only in response to endurance training.

Despite this difference, the usage of intramuscular triglycerides (IMTGs) during exercise was increased after both trials:

"In comparison to pre-training, net IMTG break- down in type I fibres was significantly greater following training (training×time interaction; P<0.05), with no difference in net IMTG breakdown between groups. Both pre- and post-training, the reduction in IMTG content in type I fibres was attributed to decreases in IMTG density after SIT (pre-training, 21±13%; post-training, 38±7%) and ET (pre-training, 20±17%; post-training, 32±8%)." (Shephard. 2013)

The greater increase in IMTG response to exercise in the SIT (HIIT) group appears to be in line with the previously mentioned role of perilipin 5 (PLIN5) as a driving force of intracellular muscle triglyceride mobilization. After all, the PLIN5 expression of the interval training group increased to a significantly greater degree than the one of the endurance training group. A subsequent correlation analysis confirmed strong associations of PLIN2 und PLIN5 with IMTG breakdown and modest associations with muscular insulin sensitivity.

Para- vs. sympathetic overtraining: I would venture the guess that most of you will think of performance decrements, fatigue, depression, increased sleeping needs, constant weight or even fat gain, and lowered heart rate, i.e. the characteristic symptoms of parasympathetic (=addisonoid) overtraining, whenever they hear or read the term "overtraining". Its evil sympathetic twin, which is also known as basedowoid overtraining (named after morbus basedow) and likewise associated with performance decrements and fatigue yet in combination with an almost stimulant like restlessness, disturbed sleeping patterns, weight loss, and accelerated heart rate, is yet way less know. So, if you wake up in the middle of the night sweating like a pig and with a heart rate similar to the one you had during your last HIIT session, you better cut back on the weight lifting and HIIT side of your regimen - w/out necessary increasing the aerobics, though.

Bottom line: If you combine these mechanistic insights, with the main outcomes of the Cocks paper, which found ET and SIT "equally effective at decreasing arterial stiffness and increasing skeletal muscle capillarisation and eNOS content", even HIIT (or SIT, as it's called here) haters will be hard pressed to argue with Shephard et al.'s conclusion that..

"[d]espite the large differences in duration and energy expenditure between SIT and ET, we provide novel evidence indicating that SIT induces similar improvements [in almost all measured parameters and] provides a time-efficient exercise alternative to achieve improvements in aerobic fitness and insulin sensitivity." (Shephard. 2013)

So, now it's up to you 3x per week HIIT or 5x per week SIT? The answer appears to be clear, however, for people who are also strength training on a higher volume / density regimen, the addition of only 2-3 low(er) intensity aerobic sessions may still be the "safer" alternative in order not to overtax the sympathetic nervous system and keep a balance between sympathetic and parasympathetic activation in your routine.

More, really short news

Put introduction here

• Hazelnuts: A polyphenolic "superfood" that's prebiotic by nature (Montella. 2013) -- The skin of hazelnuts has only recently been identified as "one of the richest edible sources of polyphenolic compounds" - a polyphenol source that can compete with green tea and coffee, by the way (Clani. 2013).
  
  

  

  Hazelnut peel is laden with gut friendly prebiotics & antioxidant plyphenols

  In a paper that's soon going to be published in Food Chemistry researchers from the Italy and the United States report that the skin does also contain a whole host of potent pre-biotics:

  "Over thirty complex free oligosaccharides, composed mainly of galacturonic acid and N-acetylgalactosamine, were characterized for the first time in the present study. Their concentration ranged between 16 mg and 34 mg per g of extract." (Montella. 2013)

  And if you find that unfair, because you are allergic, you may be interested in a 2005 paper by Enrique et al. who found that their sublingual immunotherapy for hazelnut food allergy worked quite well in a first randomized, double-blind, placebo-controlled study with a standardized hazelnut extract (Enrique. 2005)

• 

  Inonotus obliquus (chaga mushroom) does actually looks like a tumor, but contains compounds that have the ability to kill prostate and breast cancer cells (photo by Tomas Čekanavičius)

  "Eat your mushrooms!" mothers are probably saying that not often enough (Kalogeropoulus. 2013; Ma. 2013) -- According to a recent study by Nick Kalogeropoulus et al. all five five wild edible mushrooms species (Lactarius deliciosus, Lactarius sanguifluus, Lactarius semisanguifluus, Russula delica, Suillus bellinii) from Lesvos Island, the researchers recently analyzed in their laboratory contained significant amounts of polyphenols, with the more abundant ones being p-OH-benzoic acid, p-OH-phenylacetic acid, o-coumaric acid, ferulic acid and chrysin. Moroever, the Greek scientists were also able to isolate the riterpenic acids oleanolic and ursolic acid (yeah, that stuff that's currently sold as test booster).
  
  If you add to that the not even published results of Ma, Chen, Dong and Lu, who fount that the ergosterol, ergosterol peroxide and trametenolic acid in Inonotus obliquus (chaga mushroom), another mushroom that has been used in TCM for centuries, do not only have potent anti-oxidant activity, but can also kill human prostate and breast cancer cells, the initially raised question, why your mother never told you to "eat your mushrooms" suddenly appears in a very different light, doesn't it?

• Did you know that the aggregate-accessory fruit (with the green dots on its flesh being its "nuts") has the highest total antioxidant capacity, when it's still green (see facebook news), can contain up to 160mg/g of fisetin (Kimira. 1998) and that the latter has been shown to reduce thyroid peroxidase activity (Divi. 1996) and thus to protect against thyroid cancer? Fisetin is also supposed to have anti-allergic and anti-angiogenic (pro - cardiovascular health) effects.
  Strawberry polyphenol fisetin ameliorates hepatic steatosis and lowers circulating glucose concentrations (Cho. 2013) -- While it's still a couple of days until the Strawberry season will begin it's still good to know in time that the fisetin content in strawberries can ameliorate hepatic steatosis and decrease blood glucose levels by increasing GLUT-4 (glucose transporter 4) expression in a rodent model of diet induced obesity.
  
  Unfortunately, the changes the Korean scientists observed in response to a human equivalent dose of 130mg/day was statistically significant yet not uniquely impressive and "thanks" to the increase in PPAR-gamma and the non-selective increase in GLUT-4 receptor expression (measured only on adipocytes), the rodents in the supplemented group got exactly as obese as their unsupplemented pears. Nevertheless, better "weighty" and healthy than skinny fat and sick, right? 

• Scientists find alternative androgen pathway - DHT synthesis from progestorone more effective than from testosterone (Kamrath. 2013) -- Usually it's my friend Carl Lanore who says that he, respectively Super Human Radio has the smartest listeners. I would hovewer argue that listening is easier than reading the stuff I produce (including sentences that are longer than the paragraphs of most other bloggers) and therefore it's no wonder that SuppVersity readers must be at least as smart ;-)
  
  

  

  The alternative pathway to androgen (DHT) synthesis as proposed by Kamrath et al.

  That being said, I just received a facebook message from Rob, who pointed me towards a very recent paper claiming that there was an "alternative androgen synthesis pathway" in human beings. "Alternative pathway?" Sounds like the adrenal gland and the DHEA => Testosterone => DHT pathway, right? That's what I thought, as well, but actually this one is different. As the pediatric scientists from the JLU Gießen (Germany) point out in their review of the literature, there is a hitherto largely overlooked "backdoor" by the means of which 17α-hydroxyprogesteron instead of it's 12,30 lyase product androstendione is 5α-reduced to 17α-hydroxy-dihydroprogesteron, which is then, in a 4-step process converted to 17α-hydroxyallopregnanolon (2α-HSD), Androsteron (12,20-Lyase), androstandiol (17b-HSD) and finally DHT (3α-HSD).

  "This so-called "backdoor" synthesis pathway appears to play an important role especially during the development of male fetuses, since respective defects will result in a suppressed virilization in boys." (Kamrath. 2013)

  Another context that's probably more important for most of you is the role of the "backdoor" in castrate (and probably also androgen suppression) resistant prostate cancer, where this alternative pathway jumps in, when the regulate substrate for DHT synthesis by a mere change in the specific 5α-reductase subtypes.

Now don't tell me you still haven't had enough for today? I mean, with the long article on the sprint vs. endurance study you've just gotten day 4 of the SuppVersity Exercise Science Week, and with the other short notice items, even those of you who have been missing nutrition and other news within the past couple of days should have gotten way more than your money's worth - after all, the SuppVersity is still free!

Since the same also goes for the facebook news, I'd suggest you head over to the SuppVersity Facebook Wall, where you will find roughly half a dozen of additional short news items every day. Examples? This is a selection of what you could already have known if you were already a friend, fan or whatever you call that on facebook, when you click on the "like button" at www.facebook.com/SuppVersity:

Just out: Part II of my interview with Sean Casey. This time about the A-Z of supplements for strength, endurance and all other trainees who want to boost their health and performance (read more)

• Skin protection from within - Orally ingested green tea or rather respective catechin metabolites end up in your skin and protects it from UV radiation (read more)
• Iron deficiency starts in the gut - Epidemiological findings confirm: Even people with mild gastrointestinal inflammatory bowel disease need more iron and co-factors in their diet to prevent deficiency than healthy individuals (read more)
• Hormonal contraception increases risk of HIV infection - Medroxyprogesterone acetate (MPA) suppresses both innate and adaptive arms of the immune system resulting in a reduction of host resistance to invading pathogens (read more)
• Grape seed and peel extracts stop working, when they are "purified" - Another case where man shalt not isolate what nature put together, if he wants to have the active ingredients survive the digestive process (read more)

And when you are done with those and i have not yet posted another handful of news, head over to Part II of my interview on CasePerfomance.com. Afterwards, you hit the power button switch off this damn machine and have a nice weekend with family and/or friends. 

References:

• Calani L, Dall'Asta M, Derlindati E, Scazzina F, Bruni R, Del Rio D. Colonic metabolism of polyphenols from coffee, green tea, and hazelnut skins. J Clin Gastroenterol. 2013 Oct;46 Suppl:S95-9.
• Cocks M, Shaw CS, Shepherd SO, Fisher J, Ranasinghe AM, Barker TA, Tipton KD, Wagenmakers AJ. High intensity interval and endurance training are equally effective in increasing muscle microvascular density and eNOS content in sedentary males. J Physiol. 2013 Sep 3.
• Divi RL, Doerge DR. Inhibition of thyroid peroxidase by dietary flavonoids. Chem Res Toxicol. 1996 Jan-Feb;9(1):16-23.
• Enrique E, Pineda F, Malek T, Bartra J, Basagaña M, Tella R, Castelló JV, Alonso R, de Mateo JA, Cerdá-Trias T, San Miguel-Moncín Mdel M, Monzón S, García M, Palacios R, Cisteró-Bahíma A. Sublingual immunotherapy for hazelnut food allergy: a randomized, double-blind, placebo-controlled study with a standardized hazelnut extract. J Allergy Clin Immunol. 2005 Nov;116(5):1073-9.
• Kalogeropoulos N, Yanni AE, Koutrotsios G, Aloupi M. Bioactive microconstituents and antioxidant properties of wild edible mushrooms from the island of Lesvos, Greece. Food Chem Toxicol. 2013 Jan 24. 
• Kamrath C, Hartmann MF, Wudy S. The alternative androgen synthesis pathway in humans. Klin Padiatr. 2013 Jan;225(1):3-7. [Article in German]
• Kimira M, Arai Y, Shimoi K, Watanabe S. Japanese Intake of flavonoids and isoflavonoids from foods Journal of Epidemiology. 1998; 8:168–175.
• Ma L, Chen H, Dong P, Lu X. Anti-inflammatory and anticancer activities of extracts and compounds from the mushroom Inonotus obliquus Food Chemistry. Feb 2013 [in press]
• Montella R, Coïsson JD, Travaglia F, Locatelli M, Bordiga M, Meyrand M, Barile D, Arlorio M.dentification and Characterization of Water and Alkali Soluble Oligosaccharides from Hazelnut Skin (Corylus avellana L.) Food Chemistry. Feb 2013 [in press]
• Shepherd SO, Cocks M, Tipton KD, Ranasinghe AM, Barker TA, Burniston JG, Wagenmakers AJ, Shaw CS. Sprint interval and traditional endurance training increase net intramuscular triglyceride breakdown and expression of perilipin 2 and 5. J Physiol. 2013 Dec 17.
• Thvilum M, Brandt F, Almind D, Christensen K, Hegedüs L, Brix TH. Excess Mortality in Patients Diagnosed With Hypothyroidism: A Nationwide Cohort Study of Singletons and Twins. J Clin Endocrinol Metab. 2013 Jan 30.