Making HIIT a Hit Part II/II: Training Optimization? Where Do I Start? Theoretical Considerations & 10 Rules of Thumb

The stop watch is your friend, when it comes to HIIT optimization.

After the examples selected examples in the previous installment the intention of this 2nd part of the serious is to find some more general rules of HIIT program optimization with a special focus on exercise and performance on the one hand and fat loss and improvements in body composition on the other hand.

Now, if you want to optimize something, you often have one or a set of parameters you can plug into a system of linear equations to find those parameters which generate the maximal output.

Unfortunately, we are not only lacking linear, but any form of exact equations, but are also at a loss how programming is actually done. In that, Laursen's & Jenkins' definition of optimization as identifying

"[...] the optimal exercise intensity, exercise duration and number of interval bouts, in addition to the type (active vs passive) and duration of the recovery between exercise bouts."

May be helpful, but leaves us with the problem that

"[t]hese variables require manipulation according to the periodisation phase of annual training programmes, training status and the individual response that an athlete has to a training stimulus." (Laursen. 2002)

In essence, although more than 10 years have passed since the publication of this paper and the number of pertinent studies has increased, we are still (and will probably always be) at a loss when it comes to identify a single best HIIT protocol that will yield optimal results for everyone.

How do we define intensity?

In fact, even the way by which the exercise intensity is best prescribed, has as of now not been standardized. The most popular way probably is by VO2Max levels, but there are alternatives which could in fact be quite useful, e.g.:

• Your exercise selection should mirror the demands of the sport you are training for. Anyone competing in one of the classic team sports, will probably benefit most from sprints (either outside or on the treadmill). A cyclist will use the bicycle and a rower the rowing machine. Don't use equipment where you have to tweak the resistance not the speed (e.g. many of the old crosstrainers) to increase the intensity. HIIT is supposed to be fast and thus hard, not hard and thus slow!
  anaerobic threshold - intensity at which the exercise become predominantly anaerobic
• T_vent, T_lac - time to ventilatory threshold, time to lactate threshold
• OBLA - The onset of blood lactate accumulation  
• critical power - intensity that can be maintained for 30-60min
• V_max - min.speed required to reach the ventilatory threshold in an incremental exercise test
• T_max - time an athlete can run at Vmax

Now, let's be honest. How many of you know their VO2max? Or the time and speed at which you get there? If we simply assume that V_max is about 90% of what you would call "all-out" it does yet appear that the T_max value was one of the better ways to prescribe the training intensity during high intensity interval training (cf. Billat. 1998). Since there is no clearcut relation between VO2Max, V_max and T_max (25% inter-individual variation of T_max in athletes with identical VO2max), anyways, this appears to be the most reasonable and practical approach - also because measuring 60% of T_max (assuming we approximate it as the time at 90% of all out) requires nothing but a stop watch and can be repeated on a monthly basis to adapt the training intensity.

Training for increased endurance performance and conditioning

According to studies by Billat et al. and Smith et al.  (Billat. 1999, Smith. 2003) sprints lasting 50% (1:1 work to rest ratio) and 60% (1:2 work to rest ratio) of the T_max are not just sufficient, but according to Smith et al. even superior to intervals with a length of 70% of the T_max and 1:2 work to rest ratios. Although both studies were conducted in highly trained individuals, it is likely that the T_max, which is propably way lower for recreationally active, let alone sedentary individuals, provides an appropriate gauge for "optimal" training intensities in this subgroup as well. After all, this would mean that trained athletes require longer interval durations to further augment their performance than Joe Average.

Table 1: Summary of findings in high-intensity interval-training (HIT) studies in highly trained cyclists. 3-HCoA = 3-hydroxyacyl coenzyme A dehydrogenase activity; CHOOX = carbohydrate oxidation rates; CS = citrate synthase activity; HK = hexokinase activity; PFK = phosphofructokinase activity; Ppeak = peak aerobic power output; TF100 = time to fatigue at 100%; TF150 = time to fatigue at 150% of Ppeak; TT40 = 40km time-trial performance;
β = buffering capacity; ↓ = decrease; ↑ = increase; ↔ = no change. (adapted from Laursen. 2002)

And in fact, the currently available research appears to confirm this, while evidence from HIIT studies in trained cyclists suggests that the same HIIT protocols in the 5s-60s range at 80-90% of all-out performance are probably insufficient to induce further performance increases in already trained subjects (see table 1, rows marked red), unless the intensity is upped to supramaximal levels (see table 1, last row).

Optimal interval length, interval to rest ratios and recovery times

A T_max based exercise prescription with interval lengths of 50-60% (not more) of T_max, would probably mirror these increases in "optimal" interval length from non-trained over recreationally trained to elite athletes and could therefore provide a more accurate way of planning your HIIT sessions than picking a fixed work and rest duration.

Figure 1: Effects of different rest periods between 40m sprints on sprint performance (Balsom. 1992)

Let's assume you could go for just 2 min at a 80% pace of what you perceive as all-out. You would end up at a 1min interval duration, while your body, a highly trained sprinter can maintain the very same intensity for 5 minutes will have to go for intervals of 2.5min. For both an interval to rest ratio of 1:2 seems to be a happy medium, at very short submaximal intensities (in this case 80%). As the data in figure 1 goes to show, the rest requirements can be profoundly increased for all-out 40m sprints with 60s rest after a 5.6-5.7s sprint equaling a sprint interval to rest ratio of 1:11 in "seven moderately to well-trained highly motivated male physical education students" (Balsom. 1992).

The same 1:2 rule that applied to the T_max 50-60% workouts will thus maybe fail you, when you are going faster / more intense. In this context you may also argue that rest times below 60s - just as it is the case with strength training - must be regarded as an intensity technique that's actually supposed to increase the overload on the musculature by cutting rest in-between sets.

Moreover, the increased lactate during active recovery phases has repeatedly been shown to be advantageous in terms of both lower lactate accumulation and an increased likelihood of actually achieving VO2max and thus eliciting a strong enough training stimulus to trigger an adaptive response (see review in Billat. 2001; 22-23).

Can you combine intervals with a strength training routine?

Now, I would assume that most of you are no endurance athletes. So the aforementioned studies, which either were HIIT stand-alone studies or - in the case of the trained athletes - studies in which the participants replaced 1-2 of their regular aerobic exercise training with HIIT training do not answer the still highly debated question whether you can or cannot do both HIIT and strength training. I have already pointed out in previous posts that doing so on separate days doesn't seem to be a problem. However, if you "HIIT it" on the day you would usually do say chest and back. You would obviously have (a) the time and (b) the regenerative capacity to add another workout day to your week if you did not want to switch from a 3- to a 2-day split.

Baking soda could help managing the additional load (read more)

Against that background, I was not really surprised that DoesObamaEvenLift mentioned a pertinent paper by researchers from the University of Sao Paulo in his (or her?) comment beneath the first installment of this series. In this particular study (de Souza. 2012), the researchers wanted elucidate if the combination of HIIT + hypertrophy oriented strength training would hamper the benefits of one or another and whether the molecular adaptations would explain the differential effects on conditioning, strength and body composition of 43 active male physical education students who did not engage in any regular strength and aerobic power/capacity training within the last 6 months.

The good news for all muscle heads: Despite the differences in molecular adaptations between training regimens, 8 weeks of concomitant training (CT), i.e. the combination of interval training and lifting on one day did not blunt muscle strength and hypertrophy increments when compared with strength training (ST; 8-12RM for a total of leg-press 45 °, knee extension and knee flexion with 90-120s rest between sets) alone. The bad news is however that this protocol has little to do with the workout regimen of the average gymrat, who trains on 3x or more days per week and doesn't do "leg days" (without squats) on each of those days.

Figure 2: Illustration of the way the scientists tweaked the different parameters of the HIIT protocol to make it gradually more demanding from week 1-8 (left) p-AMPK and p-AKT response to different types of exercise (C: sedentary control; IT: interval training; ST: strength training; CT: concomitant training; based on de Souza. 2012)

So, while it cannot be said whether muscle or strength gains would be hampered in the long run, the way the scientists tweaked the interval part of the workout from week 1 to week 8 by slowly increasing the running speed 80-100% of the speed at which they had been running in the previous test to achieve VO2max, while increasing the rest between sets and accommodating for the additional strain of going at 95%-100% by cutting back the volume (see figure 2 left) stands in line with what has been said about the complex relation of these parameters in the previous paragraphs.

Don't forget the progression if you want to make progress

If your goal is to actually increase your conditioning and VO2max a carefully planned progression is an absolute must. To to so it would appear reasonable to re-test the initially discussed T_max after 6-8 weeks in the course of which you would progress from 80% to 95-100% in a way similar to what the participants in the study did. Based on the change in T_max you would then increase the length of the intervals appropriately while keeping the rest times similar. If your T_max for example had gone up by ~20% during the last cycle, you  would start your 2nd cycle with 72s intervals at 80% with the same progression you have used before.

HIIT for metabolic benefits and improved body composition

It's actually quite funny that up until very recently, HIIT training has been completely overlooked by most researchers who are looking for optimal exercise modalities to ameliorate. Within the last 2-5 years or so, the number of studies that suggest that high intensity interval training can do that at least as well, if not better than regular steady state aerobics is yet increasing. Here are a couple of examples, you may or may not remember from the SuppVersity news:

• 

  Previous studies have shown that a very brief interval training, even when it's performed on an empty stomach, like first thing in the morning or on an intermittent fast is not catabolic, but will in fact increase protein synthesis by 43% in men and  122% in women (read more).

  Some HIIT For Life & Less LISS For More! How to Burn 27,300 Kcal Extra W/out Losing a Single Extra Pound of Fat! (read more)
• The Iranian HIIT Solution: Three 200m Sprint Sessions per Week Double Insulin Sensitivity & Normalize Leptin Levels (read more)
• Reduced Exertion High Intensity Training - A Minimalist 2x20s HIIT Protocol For The Male Convenience Generation. (read more)
• HIIT is the Hit! Interval, not Steady State Aerobics is the Way to Go - Even for Patients with Myocardial Infarctions! (read more)
• HIIT-ing Health: Positive Effects of High Intensity Training on Symptoms of Metabolic Syndrome. (read more)

• overview of all posts with he keyword HIIT

When you go through these studies you will realize that it's impossible to identify the single-best HIIT workout for fat loss, what appears to be clear though, is that fat loss workouts do not require the same long intervals athletes with an already high VO2max need to promote their conditioning.

While the longer intervals may in the end burn more energy, the previously mentioned increase in lactate suggests that the additional energy expenditure in the course of the workout (a) does not come from your fat stores and (b) could take its toll, when you are dieting. Against that background, an "optimal" HIIT fat loss routine will probably be characterized by shorter, highly intense sprints and longer active recovery between the sets, with the latter giving your ramped up metabolism time to tap into the fat reserves, get rid of the lactate and ready for the next HIIT stimulus.

Combining HIIT and aerobic training to augment fat loss

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 (read more)

A similar rationale is actually behind the idea of combining HIIT and aerobic exercises in a single fat loss workout that consists of an initial HIIT part of 3-5 intervals at 90-95% of what you could be sprinting for 30-45s interspersed by 2-3 minutes of active recovery followed by 15-20min of light intensity steady state of an intensity that would equal walking or very light jogging on a treadmill. With a total workout duration of ~30-45min this should yet be done on a day of it's own.

A viable alternative for everyone who doesn't want to give up on their current strength training routine and doesn't have room for another training day would be to alternate between the shorter varieties of the HIIT part and the LISS part of the aforementioned workout as an adjunct to a short, but intense resistance training regimen (30-40min total with no more than 18-20 sets).

How to progress when you are dieting?

As obligatory as a progression in intensity and duration of the intervals may be for someone who's trying to increase his or her conditioning and VO2max, it is nothing I would suggest on a diet. Unless you are trying to progress from overweight or obese to normal and are in real bad shape, it is not exactly likely that your performance will be increasing to an extend that will require adaptations.

That said, it is not necessary and in most cases counterproductive to increase the workload, when what you would actually have to do to drop body fat is to reduce your energy intake. Have patience and simply stop dieting, when your progress stalls for 2 weeks (sometimes even an additional refeed can reignite the weight loss).

Can HIIT help me make lean(er) gains?

8x Increase in "Mitochondria Building" Protein PGC1-Alpha in Glycogen Depleted Elite(!) Cyclists: Training Revolution or Recipe for Disaster?  (read more)

Personally, I have had greater success with very light steady state cardio like walking on an inclined treadmill either in the morning or after a strength workout, but if you take a look at the aforementioned SuppVersity post about increase protein synthesis (see image with sprinting guy and girl next to the list of examples), or take both the results of the Psilander study that was on the news in October 2012 and the latest revelations about PGC-1 A4 and how it may benefit from pre-workout glycogen depletion, a short but intense HIIT training right before your workout may not only help you to stay lean, but could actually improve your progress - assuming you don't end up seriously overtrained and are willing to eat enough.

Are there any supplements that can help?

Aside from the regular fat loss adjuvants, a combination of creatine, caffeine and amino acids, as it was used in a 2010 study by Smith et al. would be a basic stack to increase your HIIT and overall workout performance and thus augment body fat loss. If you use BCAAs this would also make a good addition to any fasted HIIT regimen in the morning for those of you who follow an intermittent fasting protocol.

Figure 3: Lactate, pH, ratio of hydrogen carbonate ions to NaHCO(3) and base excess in blood after, as well as number of total reps performed during a leg workout (data adapted from Carr. 2012 - discussed on 09/05/12)

Also, the addition of baking soda, may be worth trying, because the increased alkalinity with concomitantly increased workout intensities could provide both metabolic (=lower propensity to gain fat) and performance (=increased growth stimulus) advantages.

Too many stimulants or stim-laden fat burners, on the other hand, are probably rather counterproductive. Their ability to free fat from the adipose tissue is of no avail, when you are "bulking" - in the worst case it may even repartition the fat from the periphery to the trunk. So you better tick to one serving of stims before a workout.

10 rules of thumb to help you making HIIT a Hit

I could probably ramble on forever, but don't think that this will provide any significant insights beyond what I have written in the previous paragraphs. So let's put an end to this endless post and formulate a couple of rules of thumb:

1. Don't get overtly focused on HIIT there are benefits to steady state exercise, as well; and it goes without saying that you won't be willing to give up weight lifting completely. You can better live without HIIT and just lifting + LISS than with HIIT only.
2. If you want to improve your conditioning, you will have to train on the higher end of the 15s to 4min interval continuum.
3. If you want to improve your body composition, training at the lower end of the 15s to 4 min interval continuum and combining shorter HIIT workouts with either strength or aerobic work appear to be more promising.
4. Active rest should always be preferred over passive rest, regardless of your goals
5. The length of the rest periods should increase with increasing training intensity
6. If you are doing HIIT for fat loss, longer active rest (up to 5 min) can actually increase the amount of fat you burn and may be a viable alternative for an additional LISS workout
7. Creatine, BCAAs, caffeine and baking soda, can be used before a HIIT workout regardless of your training goals
8. Continuous progression is obligatory, if you want to maximize your conditioning
9. Stick to the same intense, but short HIIT regimen, when you are dieting in order not to fall victim to the "doing more and eating less downward spiral".
10. Know your limits and don't simply add hours of HIIT to your current regimen.

Based on these rules of thumbs and the rest of the information in this installment, as well as the examples in the previous installment you should actually be able to come up with some kind of workout you believe you can benefit from. Give it a two week trial before you decide whether it's too hard, too easy or whatever and don't expect magic results. In the end, HIIT is like a potent supplement: Those who have what it takes to make progress without it will benefit. Those who have stalled on each and every regimen they tried, will stall on hit as well (most likely because they overtrain and/or follow  a crappy diet).

References:

• Balsom PD, Seger JY, Sjödin B, Ekblom B. Maximal-intensity intermittent exercise: effect of recovery duration. Int J Sports Med. 1992 Oct;13(7):528-33.
• Billat V, Binsse V, Petit B, Koralsztein JP. High level runners are able to maintain a VO2 steady-state below VO2max in an all-out run over their critical velocity. Arch Physiol Biochem. 1998 Feb;106(1):38-45.
• Billat VL, Flechet B, Petit B, Muriaux G, Koralsztein JP. Interval training at VO2max: effects on aerobic performance and overtraining markers. Med Sci Sports Exerc. 1999 Jan;31(1):156-63.
• Billat LV. Interval training for performance: a scientific and empirical practice. Special recommendations for middle- and long-distance running. Part I: aerobic interval training. Sports Med. 2001;31(1):13-31. 
• de Souza EO, Tricoli V, Roschel H, Brum PC, Bacurau AV, Ferreira JC, Aoki MS, Neves-Jr M, Aihara AY, da Rocha Correa Fernandes A, Ugrinowitsch C. Molecular Adaptations to Concurrent Training. Int J Sports Med. 2012 Oct 8.
• Gunnarsson TP, Bangsbo J. The 10-20-30 training concept improves performance and health profile in moderately trained runners. J Appl Physiol. 2012a Jul;113(1):16-24. 
• Gunnarsson TP, Christensen PM, Holse K, Christiansen D, Bangsbo J. Effect of additional speed endurance training on performance and muscle adaptations. Med Sci Sports Exerc. 2012b Oct;44(10):1942-8. 
• Laursen PB, Jenkins DG. The scientific basis for high-intensity interval training: optimising training programmes and maximising performance in highly trained endurance athletes. Sports Med. 2002a;32(1):53-73. 
• Laursen PB, Blanchard MA, Jenkins DG. Acute high-intensity interval training improves Tvent and peak power output in highly trained males. Can J Appl Physiol. 2002b Aug;27(4):336-48.
• Lindsay FH, Hawley JA, Myburgh KH, Schomer HH, Noakes TD, Dennis SC. Improved athletic performance in highly trained cyclists after interval training. Med Sci Sports Exerc. 1996 Nov;28(11):1427-34.
• Smith AE, Fukuda DH, Kendall KL, Stout JR. The effects of a pre-workout supplement containing caffeine, creatine, and amino acids during three weeks of high-intensity exercise on aerobic and anaerobic performance. J Int Soc Sports Nutr. 2010 Feb 15;7:10.
• Stepto NK, Hawley JA, Dennis SC, Hopkins WG. Effects of different interval-training programs on cycling time-trial performance. Med Sci Sports Exerc. 1999 May;31(5):736-41.
• Stepto NK, Martin DT, Fallon KE, Hawley JA. Metabolic demands of intense aerobic interval training in competitive cyclists. Med Sci Sports Exerc. 2001 Feb;33(2):303-10.
• Westgarth-Taylor C, Hawley JA, Rickard S, Myburgh KH, Noakes TD, Dennis SC. Metabolic and performance adaptations to interval training in endurance-trained cyclists. Eur J Appl Physiol Occup Physiol. 1997;75(4):298-304.
• Weston AR, Myburgh KH, Lindsay FH, Dennis SC, Noakes TD, Hawley JA. Skeletal muscle buffering capacity and endurance performance after high-intensity interval training by well-trained cyclists. Eur J Appl Physiol Occup Physiol. 1997;75(1):7-13.

HIITing Diabetes With the Hammer: 20min of Low-Volume High-Intensity Interval Training is Enough! + Metabolic Benefits and Optimum Interval-Format for Healthy People!

Figure 1: Number [in millions!] of prediabetics and diagnosed and undiagnosed diabetics in the USA according to data from the American Diabetic Association from January 2011 (ADA. 2011)

You probably remember Wednesday's news-item on high-intensity interval training (HIIT) for cardiac patients - as it turned out, even 2 weeks after myocardial infarction our central pump needs real exercise to get back in, or to get into even better shape. Today, I do yet want to go beyond infarction patients and address another, ever-growing sub-group of the self-perceived "victims" of the obesity pandemic, the type II diabetics.

About a month ago, J.P. Little and his colleagues from the University of British Columbia Okanagan published a study in the Journal of Applied Physiology (Little. 2011a), the results of which confirm (once again) the unpopular hypothesis that getting your ass off the couch in order to work it off in the gym hard (!) is the only way to treat a (largely) self-induced health condition that is plaguing 8.3% and threatening another quarter (79 million people with pre-diabetes) of the US population (ADA. 2011, cf. figure 1).

In the Little study (pun intended ;-), it took 8 type 2 diabetics no more than 60 minutes of intense exercise at 90% of their maximal heart rate (+another 60 minutes of rest in between intervals) to

[...] rapidly improve glucose control and induce adaptations in skeletal muscle that are linked to improved metabolic health

120 minutes (!) of which only 60 were spent doing 10x60s intervals on a cyclometer brought about changes, no pharmaceutical (or even supplement) will ever produce (without significant side effects). 120 minutes spread across 6 exercise sessions in the course of two weeks, i.e. 3 sessions of 20 minutes per week - probably 20 minutes the majority of the 8 overweight (BMI 32.6kg/m²) diabetics would otherwise have spent on their couch in front of the TV, or - with comparably small benefit - trampling away at 65% of their VO2Max on a recumbent bike. With intervals at 90% of their maximal heart rate, however, the

[...] average 24-h blood glucose concentration was reduced after training (7.6±1.0 vs 6.6±0.7 mmol/L) as were the sum of the 3-h postprandial areas under the glucose curve for breakfast, lunch and dinner (both p<0.05).

More importantly, though, HIIT training set the stage for future improvements by improving the capacity of the trainees mitochondria to handle / burn nutrients, with the >3.5x increase in GLUT-4 acticity indicating a profoundly increased capacity for glucose uptake and the +20% increase in citrate synthase activity indicating an increased capacity for substrate oxidation (energy usage) in the cellular power plants of the 8 diabetics (cf. figure 2).

Figure 2: Improvements citrate synthase, protein content of 70kDA subunit, complex III core 2 protein, complex IV subunit IV, mitofusion 2 and Glut-4 activity - all markers of mitochondrial capacity / efficiency - after 6 sessions of 10x60s cycling at 90% HRmax in 8 diabetic patients (data calculated  based on Little. 2011a).

These improvements, and this is a result from a previous study by Little's group (Little. 2011b), were - at least in part - a result of the effects HIIT has on mitochondrial biogenesis, of which Little et al. found that it is profoundly elevated in the first 24h after the exercise bout (3h post: +70% nuclear PGC-1alpha/Tubulin, 24h post: +60% whole muscle PGC-1alpha/Tubulin; +150% increase in p-p38MAPK) - and all that after a single session of a all 4x30s all-out Wingate cycling tests separated by 4 min of rest).

Now, let me ask you: Do we really ask too much of our fellow (and mostly ridiculously lazy) human being, if we ask them to invest one hour of their life per week to exercise into a, no, their healthier future? I wouldn't think so!

Figure 3: Fat oxidation in kJ per minute during 60 min of cycling at 60% VO2Max before and after 7 sessions of HIIT training in eight healthy, normal-weight recreationally active women (Talanian. 2006).

Metabolic benefits of HIIT training: Now, you may well ask yourself, why you should a give a damn about those changes, well... would it convince you, if I told you that in a 2006 study Talanian et al. were able to show that after 7 sessions of serious HIIT training (10x4 min at 90% HRMax with 2 min rest between intervals) the amount of body fat the eight female study participants burned during cycling at 60% of VO2Max was increased by 36% (Talanian. 2006)? in other words, the HIIT sessions primed the bodies of the "recreatinally active women (22+/-1 yr old, 65.0kg body wt, 2.36l/min VO2peak) to burn more fat during subsequent cycling at the lower end of the "fat-burning zone"! As the data in figure 3 shows, this effect was partly, because the subjects switched more readily into "fat burning mode" - a priming effect from the HIIT sessions.

HIIT, yeah... but how to find the right dosage?

Both the Moholdt, as well as the Little study have shown that it does not take much to induce profound health benefits - but what would be the optimal dosage for YOU, who, as a diligent student of the SuppVersity, are probably (or should I say hopefully) neither an overweight diabetic nor a cardiac patient?

Figure 4: Changes in body weight, body fat (%), peak lactate levels, perceived exertion (RPE) and VO2Max (rel. to body weight) after low intensity continuous training or three different HIIT protocols in recreational cyclists (data calculated based on Seiler. 2011)

Apparently, a group of scientists from Kristinsand (again in Norway, where the descendants of the Vikings obviously are tough enough fore real exercise ;-) asked themselves the exact same question (Seiler. 2011). In the course of a 2 months study they had 29 male and 6 female recreational cyclists, whose VO2Max of 53+/-6 ml*kg/min were ~56% higher than those of the cardiac patients (after the intervention) in the Moholdt study, perform 2 HIIT sessions per week (plus 2-3 weekly low-intensity bouts) of one out of three different interval training programs: 4x4min, 4x8min, or 4x16 min at 94%, 90% or 88% of their respective maximal heart rates.

Hard, but neither torturous, nor time consuming

The results, I have plotted in figure 4, confirm that HIIT must be hard, but neither torturous nor time-consuming. Or as the scientists put it:

The 4x8 min prescription induced greater physiological adaptation than both lower and higher intensity interval programs of 64- and 16-min total duration but was perceived as less stressful than 4x4 min at ~95% HR max . These findings suggest an important interaction between accumulated work duration and work intensity that can be optimized for inducing maximal physiolo gical adaptations at manageable RPE [rates of perceived exertion] in endurance athletes performing interval training.

Image 1: Spinning at ~90% of your max heart rate
would be one way to do 4x8 intervals.

On that note, it may also be interesting that in line with the +91% increase in time to exhaustion Seiler et al. observed in the 4x8 HIIT group (vs. +12% in low intensity and +62% and +63% in 4x16 and 4x4 HIIT programs) and the increased respiratory exchange rate Moholdt et al. observed in their study (cf. Wednesday's news), A.D. Hafstadt and his colleagues from the University of Tromsoe (Hafstadt. 2011) have found in a mouse-model (where cutting out the heart and measuring its weight obviously is not so much of an issue as it would be with human subjects ;-) that despite similar increases in the heart to body weight ratio (+10%), ...

[...] only HIT altered cardiac substrate utilization, as revealed by a 36% increase in glucose oxidation and a concomitant reduction in fatty acid oxidation, [...] improved cardiac efficiency by decreasing work-independent myocardial oxygen consumption and increased cardiac maximal mitochondrial respiratory capacity.

These findings lead the scientists to conclude that "high intensity training is required for induction of changes in cardiac substrate utilization and energetics" and that these improvements may be at the heart (pun intended) of its "superior" ability to increase aerobic capacity - or as, I previously phrased it: HIT, not steady state aerobics, is real cardio training! You would not train a 20inch biceps with blue 2pound sand-filled plastic dumbbells, would you? I think, I will leave it on that, for today and wish you all have an intense weekend (whatever your interpretation of that may be ;-)

Image 2: There is no one-size-fits-it-all HIIT training.

Addendum of 10/01/2011: In the comments area, Oni posted a quite resonable question: "Doesn't HIIT usually employ shorter (1min) intervals? And how could 8 minute intervals, as in the Seiler study be feasible?" The answer to the first question is easy, as we just have to look at the words "high intensity" and "interval training", now obviously no one questions that the regimen Seiler et al. used, had a high intensity (90%) and employed intervals - and I think Oni does not disagree on that, but rather implies that this type of training is too intense and if the subjects had not been recreational cyclists, this could actually have been the case.

On the other hand, the results of the Seiler study also showed that shorter intervals at higher intensity lead (in this subject group) to greater rates of perceived exertion. Now, I dare say that 95% of the trainees who are doing the standard ~1min bouts of all-out exercise - are not going "all out" in the sense that they are scratching their real heart rate max. If they did, I am quite sure they would (in line with the results from the Seiler study) confirm that 8min @90% did not wear them out as much as 1min @100% of ALL OUT exercise at their  max. heart. This leaves the question to be answered, whether 4 intervals à 8 minutes are optimal for everyone? And this is fortunately a question that is easy to be answered... 4x8 is obviously for "advanced" athletes (who have been practicing some type of endurance activity already). From my training experience, I know that untrained (or less trained) trainees sometimes do not even reach "target heart rates ~90%" before they feel so exhausted that they give up.

Image 3: The type of equipment you are using will also have an influence on optimal interval length; doing 8-min all-out intervals on the treadmill certainly are no viable option - even not for highly trained athletes!

So what does that mean for your training, then? If you like doing the all-out (! don't forget to push yourselves!) 1-minute intervals, keep doing them. There are plenty of studies that confirm similarly beneficial effects on mitochondrial biogenesis with these protocols, e.g.

• 7x30s - Psilander. 2010
• 8-12x60s - Little. 2010
• 4x 30s - Giballa. 2009

If, on the other hand, you are an (endurance) athlete wanting to improve your performance, the available data would suggest that intervals in the +4min range would be the way to go (Seiler. 2004; Driller. 2009; Seiler. 2011), as they are more sport-specific. Overall, it is yet always about balancing duration (individual interval length + number of intervals + rest days in-between) vs. intensity (heart rate) to find your optimal HIIT protocol (Gross. 2007; Zuniga. 2011)

HIIT is the Hit! Interval, not Steady State Aerobics is the Way to Go - Even for Patients with Myocardial Infarctions!

Image 1: Right in the starting block is where heart health begins... and on the finish line of a marathon race probably is where heart health ends (if not much earlier)

I think it is unnecessary to pose this question again, but in case you missed the innumerable blogposts, where I asked you whether you would rather like to look like an ultra-endurance runner or like a sprinter - here you go: Whose physique would you rather want to have? The sinewy physique of Haile Gebrsellasie or the muscled physique of Usain Bolt and co? I assume in most cases this question is unnecessary... but what if you are sick, obese or even have a heart failure? Obviously you cannot train like a sprinter, then... can you? Yes, you can - at least within your personal physiological limitations! In view of the results of a recent study from the KG Jebsen Center of Exercise Medicine at the Norwegian University in Trondheim, Norway, aerobic interval training would even be the healthier choice (Moholdt. 2011)!

For their study Trine Moholdt and her colleagues recruited 107 patients who had been hospitalized for myocardial infarction 2-12 weeks before the study and randomly assigned them to usual care rehabilitation or an aerobic interval training performed. In the course of the 12 week study period the exercise protocol was performed thrice a week. Two sessions were supervised, the other one had to be performed at home.

• usual care rehabilitation program - the standard program comprised 60 minutes of aerobic exercises performed to music; the sessions were lead by a physiotherapists, and after a 10-minute warm-up, the patients did aerobic exercises like walking, jogging, lunges and squats for 35 minutes, which were followed by a 5-minute cool-down with stretching and relaxation exercises.
• aerobic interval training - the total session time of the interval training was 38 minutes; it consisted of an 8-minute warm-up, followed by 4x4-minute intervals at 85–95% of the maximum heart rate (monitored by heart rate monitor), with active rest of 3 minutes of walking at 70% of maximum heart in between the intervals; the exercise session was terminated with a 5-minutes cool-down.

In view of the still commonly held believe that interval training could easily become (over-)exerting, quite a few medical practitioners, would probably shake their heads over the "irresponsibility of [their] Norwegian collegues - how dare those idiots put ailing cardiac patients on such an tortorous exercise regimen" ... I think I won't have to continue, you know the whole litany... and if you, just like me cannot stand that anymore, and your own (your father's, mother's, grandpa's or grandma's) doctor is one of those, take the following data, print it and use it to shut him up.

Figure 1: Improvements in VO2Max, peak heart rate, respiratory exchange rate at peak heart rate and heart rate recovery in cardiac patients after 12 weeks on the usual care rehabiliation program or an intense aerobic interval training (data calculated based on Moholdt. 2011)

Obviously, the poor cardiac patients did not only survive the "torture", their hearts even thrived on it. The increase in peak oxygen uptake (VO2Max), the standard measure of aerobic performance, was 2.7x higher in the interval group than in the patients who did the usual 60-minutes reha-sessions (cf. figure 1). For the other parameters the differences were not statistically significant after analysis for initial randomization:

Flow-mediated vasodilatation, both non-normalised and normalised to shear stimulus, increased significantly after exercise training in both groups [...] Quality of life increased significantly after exercise training (between-group differences, not significant)

If we look at the blood parameters, however, we do yet see some interesting differences, even your medical practitioner could not argue away:

Figure 2: Changes in high density lipoprotein and adiponectin in cardiac patients after 12 weeks on the usual care rehabiliation program or an intense aerobic interval training (data calculated based on Moholdt. 2011)

While the changes in triglycerides, CRP, ferritin, haemoglobin, and glucose were - within their respective standard-deviations - identical in both groups, there was a marginal but statistically significant greater improvement in high density lipoprotein (HDL) levels (a statistician would say there was an improvement in the interval group, while there was none / no statistically significant one in the reha-group) in the interval group. While this would indicate a lower risk of future (recurrent) heart disease, the accompanying  increase in adiponectin would suggest that the interval training group either had already or were about to lose more body fat than their endurance trained peers.

Unfortunately, the body composition of the patients was not tracked in the study, so this leaves us with the "surprising" benefits of intense interval training for the hearts of patients with prior myocardial infarction as the main result of a study some medical practitioners would probably not even have dared conducting.

Tabata Workouts: Do They Work & How Energy-Demanding Are They? 14.5 Kcal/Min Sounds Nice, But You Must Earn It!

Tabata training is intense: So if you don't have the guts to do it on your own, find someone to suffer next to you. Trust me that'll keep you going, if you'd have long surrendered if you had trained alone. Some gyms even offer special courses.

Most of you will probably be familiar with the ultra-short + ultra-intense HIIT prescription that's known as the Tabata protocol. Not really? Well, here is the elevator pitch, then:  "Tabata training," was first described by the Japanese scientist Izumi Tabata in 1996. Tabata and his colleagues (Tabata.1996) conducted a study that compared moderate-intensity continuous training at 70% of maximal oxygen consumption (VO2max) for 60 minutes, with HIIT conducted at 170% of VO2max. The HIIT training consisted of eight, 20-second all-out exercise bouts followed by 10 seconds of rest for a total of 4 minutes of exercise. Based on what you have read about the contemporary HIIT research here at the SuppVersity, you will be aware that Tabata's protocol is more intense, but also much shorter than the currently favored HIIT regimen with their ~1-4min (sometime even 8min!) intervals at 80-100% intensity.

Now, the "original" study found that HIIT improved aerobic capacity to a similar degree as moderate intensity continuous training (aka LISS). Nevertheless, it did resulted in an impressive +28% increase in anaerobic capacity.

Tabata 2.0? Is it time for a modification?

Meanwhile Tabata training has evolved to include a variety of modes and exercises. What has always remained an essential characteristic of this type of HIIT training, though are the classic 20-10 patterns (i.e., 20 seconds of all-out effort followed by 10 seconds of rest).

According to Talisa Emberts, John Porcari , Scott Doberstein, Jeff Steffen and Carl Foster, the general physiological effects of this type of training are well documented. What would be lacking, however, is data on the the relative exercise intensity and energy expenditure of Tabata training (Emberts. 2013). Therefore, the purpose of the study at hand, which comes right from the labs of the Department of Exercise and Sport Science at the University of Wisconsin, was to determine the u exercise intensity and energy expenditure of a Tabata workout.

What did the scientists do?

In order to measure the energy expenditure, the researchers recruited 16 trained volunteers (8♂: 35.3 ± 8.1 years, 1.81 ± 0.06 m, 93.7 ± 8.70 kg, 53.2 ± 0.6 ml·kg·min -1; 8♀: 28.4 ± 9.3 years, 1.71 0.09 m, 71.9 ± 12.0 kg, 42.9 ± 11.3 ml·kg·min -1). After the usual initial fitness tests, each subject completed two identical workouts.

Table 1: .Exercises included in the 20-minute Tabata workout; each exercise was repeated twice at a ratio of 20 sec exercise/10 sec rest

• workouts consisted of four, 4-minute "segments".
• segments consisted of performing the exercises listed in table 1 twice in succession.  

• subjects completed as many repetitions of each exercise as possible in 20 seconds followed by 10 seconds of rest.

• there was 1 minute of rest between each segment.  

As Emberts et al. point out, they "chose to do the four segments of Tabata in succession, since one of the criticisms of Tabata training has been that individuals cannot burn a sufficient number of calories in 4 minutes to favourably impact energy balance" (Emberts. 2013)

Figure 1: Energy expenditure per minute and total energy expenditure in 20 vs. 4 min TABATA studies (Emberts. 2013; Olsen. 2013)

A brief glimpse at the data in figure 1 goes to show you that the relative energy expenditure per minute was as impressive as in previous studies:

"Caloric expenditure averaged 14.5 ± 2.7 kcal·min -1 , which is very similar to the value found by Olsen (2013), who reported a slightly lower value of 13.4 kcal·min -1 . This was probably due to the fact that her study included 13 women and only 3 men. Total energy expenditure ranged from 240 to 360 kcals for the 20-minute workout, which is significantly higher than the estimated 54 kcals expended during the 4 minutes of exercise reported by Olson." (Emberts. 2013)

What was also impressive, though, was the rate of perceived exertion (RPE), which averaged 15.4  ±  1.3 for the two workouts and was that rated as "hard" by these already trained subjects. I mean, ask yourself what an untrained individual would have been telling you after high knee runs, plank punches, jumping jacks, side skaters, rope jumping, in/out boats, line jumps, push-ups, burpees, russian twists, squats, lunges, mt. climbers, push-ups, split squats and box jumps... right probably nothing: The average sedentary inhabitant of the Western Obesity Belt would simply have collapsed after two exercises ;-)

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If you are a pro (and I mean "are" and not think of yourself as one) looking for an intense workout that will help you cut body fat and gain muscle at the same time, look no further. The cross-fit protocol Smith et al. used in a study I wrote about earlier this year has what you are looking for - unfortunately it has a similarly insane intensity: "From 16% to 8% Body Fat in 10 Weeks: Crossfit Workout Gets The Leanest Shredded - But Only the Fittest Survive" (learn more).

240-360kcal/s in 20 min - is that worth it? It stands out of question that trained individuals who are willing and able to give their muscles and more importantly their central nervous system the recovery time they will need after these workouts will greatly benefit from the intensity of a Tabata routine like this. This is after all, the "uncomfort zone" in which someone with years of training experience under his / her belt can still enforce adaptation.

Contrary to the trained athlete, for whom the total amount of energy expenditure is secondary to proving new "growth" (the word refers to general growth as in increases not just in muscle power or size, but also overall conditioning) stimuli, the rookie and even many intermediate trainees are however going to be overwhelmed by the physical (some also by the mental) demands of this workout. For him / or her, a combination of strength training and LISS (rookie, or someone trying to cut weight) or strength training and "regular" HIIT (advanced trainee) may be thus in fact be  better choice. Not necessarily because it would burn more calories, but rather in view of the fact that it is not as overtraining prone as a 20min session of Tabata training.

References:

• Olson M. Tabata  interval  exercise:   Energy  expenditure and post-exercise responses. Medicine & Science in Sports & Exercise 45. 2013; S420.
• Emberts T, Porcari J, Doberstein S, Steffen J, Foster C. Exercise Intensity and Energy Expenditure of a Tabata Workout. Journal of Sports Science and Medicine. 2013; 12:612-613

Beta Alanine and Baking Soda (NaHCO3), a Synergistic Duo for 4-min All-Out Sprints Even in Highly Trained Athletes?

Image 1: I guess many of the competitive track cyclists will be taking beta alanine either on its own, or as part of one of the thousands of proprietary blends in the squillion ergogenic supps you can chose from at your favorite supplement store. I am yet pretty sure that only very few of them have heard that a much more efficient ergogenic aid may be lying around unnoticed in their kitchen.

If you had to compile a list of proven (and I am not talking about the way "proven" is used by the supplement industry!) ergogenic aids and ordered them by the number of publications, carbohydrates (all types) and protein (including BCAAs and EAAs) would be at the top of the list... from then, things get somewhat more complicated, but I would guess that creatine could actually have the potential to make it to the third place - it would by all means be within the top 5. Whether this is true for beta alanine, which probably would be the #4 on the list of an increasing number of physical culturists, appears yet questionable, to say the least. After all, the number of pertinent publications is, contrary to what common wisdom suggests, not exactly "extensive", to say the least. And the total effect size of 2.85% for bouts of exercise lasting 60-240s (for <60s beta alanine had no effect), which has been calculated by Hobson et al. in a recently published review of the available literature on that subject (Hobson. 2011), is not nearly as earth-shattering as headlines like "the next creatine" would make you believe.

Beta alanine, baking soda or both? What maximizes 4-min all-out cycling performance?

Against that background and in view of the results of a recently published study by researchers from the School of Human Life Sciences at the University of Tasmania in Australia (Bellinger. 2012), it could thusly (once more) be advisable that you initially resort to the stuff that is already sitting in your kitchen cabinet, before you spend extra bucks on expensive supplements... I guess, you are now asking yourselves what the hack this idiot is talking about now, so I guess, I best let you know what you have to look for: Baking soda! As a (hopefully) faithful student of the SuppVersity, you will be aware that I am a huge fan of this cheap, readily available and - potential diarrhea aside - side-effect free alkalanizer (cf. "Baking Soda for Stressed White Blood Cells" and "Sodium Bicarbonate, An Ergogenic Aid from Your Kitchen Cupboard").

Image 2: "Cholesterol is the devil and sodium is his little brother!" Everyone who still believes everything the medical orthodoxy says, please raise your hands!

A note on the dangers of "salt": Firstly, baking soda is "only" ~28% sodium, which means that for every 4 grams you ingest you get roughly 1 g of sodium. Secondly, it is arguable how much of the sodium is effectively taken up and will be floating around in your blood. As T. Lakhanisky points out in his dossier for the Belgian government: "The uptake of sodium, via exposure to sodium carbonate, is much less than the uptake of sodium via food. Therefore, sodium carbonate is not expected to be systemically available in the body." (Lakhanisky. 2002) And thirdly, there is more and more evidence that suggests that the chloride rather than the sodium content of common table salt (NaCl = NatriumChloride) is the root cause of "sodium induced hypertension" in "sodium sensitive" individuals / animal models. Only recently, a study by Schmidlin et al. showed that chloride loading induced hypertension in the stroke-prone spontaneously hypertensive rat despite profound sodium depletion (Schmidlin. 2010). So, if you asked me, rather than pointing at salt as the #2 on the list of greatest evils (obviously cholesterol is still #1, here) the medical orthodoxy would be better advised to address the imbalances between sodium and potassium, which are so characteristic of the western diet, instead of painting yet another black and white picture where sodium is the bad guy and potassium the dangerous mineral that cannot be sold OTC in dosages >80mg.... but hey, this would be the topic for a whole new blogpost and as gross as it may sound, the chance that you get diarrhea from the baking soda is probably 1000x higher than the remote possibility of increases in blood pressure. A 1990 study by Luft et al. even found that the blood pressure of 10 mildly hypertensive and normal subjects decreased by 5mmHg after 7 days in the course of which they drank 3 liters of sodium bicarbonate containing water per day (Luft. 1990)

To elucidate the individual and synergistic effects of sodium bicarbonate and / or beta alanine on the cycling performance of 14 highly trained cyclist (age: 25.4y; weight: 71.1kg; VO2Max = 66.6 ml/kg), Bellinger and his colleagues provided their subjects in a double-blind manner with a daily dose of 65mg/kg beta alanine or placebo in capsule form (in a previous study a similar dosing regimen elicited a 57% increase in skeletal muscle carnosine). The subjects had to consume the capsules in four equal doses spread across the day to make sure that the well-known tingling would betray which of the subjects was in the active arm of the study and which received the placebo (interestingly, this still happened in two of the subjects). After the initial 28-day supplementation period in the course of which the subjects had to follow a standardized HIT training program (2 sessions per week: 8x 90%VO2Max for 2.5min followed by 3min recovery at 40%, each) in addition to their regular training which had to be accurately logged, so that the researchers would be able to identify potential confounding factors which could influence the individual results in the two subsequent performance trials. 

Training log, diet log, wash-out periods - all in the name of science

Moreover, the subjects were asked to record their dietary intake in the 24h before the first performance trial, so that they could replicate the latter on the subsequent 2nd trial, which took place after a 2-day washout period, so that the subjects which had received the active sodium bicarbonate treatment (0.3g/kg NaHCO3 with 10ml/kg water to wash the capsules down) in the first trial would not derive any remaining benefit from that in the second trial, where the subjects that had previously been assigned to the placebo group, received the NaCHO3-filled capsules, while the others swallowed a placebo 90 minutes before they performed a single 4-min maximal bout of cycling on identical air-braked, front access cycle ergometers.

Figure 1: Absolute (left) and relative (right) increase in average power and total work during 4-min all out sprints on a cycle ergometer in response to chronic (28-day) beta alanine, acute (90min pre) baking soda, or combined supplementation (data adapted from Bellinger. 2012)

From the results in figure 1 it is easy to say that beta alanine alone had did not exert statistically significant ergogenic effects during the 4-min all-out cycling bout in this group of highly trained athletes - a finding, by the way, of which the researchers state that it "is consistent with previous literature investigating the effects of β-alanine supplementation on maximal exercise efforts in trained populations". The increases in average power (p = 0.036) and total work (p = 0.044), on the other hand, were likewise not earth-shattering, but statistically significant and could well make the difference between victory and defeat in one of the track cycling races during the upcoming Olympic games in London.

Sodium bicarbonate only for track cyclists? And what about beta alanine?

While obviously the fewest of you will be professional track cyclists, some of you may perform other sports which require intermediate all-out sprints in the 2-6 minute range - you, and everyone who is doing some sort of "sprinting" exercise as part of his / her high intensity (interval) cardio training, once in a while could thusly very well benefit from the ph-buffering effects of baking soda - probably even more so than from beta alanine, of which I am still surprised that people are taking it chronically. After all, the wash-out period for beta alanine is >15 weeks and does not appear to depend on either the amount or intensity of exercise that is performed (Baguet. 2009; Stellingwerff. 2011). It would thusly be prudent to load up on carnosine by supplementing ~800mg of beta alanine for 6 weeks once in a while to maximize the intra-muscular buffer-capacity and to use a whopping dose of 0.3g/kg sodium bicarbonate, whenever you feel that you need a small, but statistical significant performance boost or just want to make sure not to get over-acidic during your workouts.