HMB 'Likely' Protects 'Muscle Quality' & 'Possibly' to 'Likely' Cuts Inflammation During 23-Day Intense Military Training

HMB 'Likely' Protects 'Muscle Quality' & 'Possibly' to 'Likely' Cuts Inflammation During 23-Day Intense Military Training

build muscle high intensity HMB HMB-FA military training muscle damage performance

Unfortunately, the study at hand provides insufficient evidence to decide whether you should buy (free acid) HMB if you are about to participate in a military bootcamp.

The idea that HMB is the rather anticatabolic version of leucine, I've mentioned in previous articles, obviously occurred to an international group of scientists from the University of Central Florida, the Israel Defense Forces as well as associated universities, too (Hoffman. 2016).

In their recent study, the scientists examined whether HMB supplementation can attenuate muscle loss and the inflammatory response during highly intense, sustained military training. A study, of which Hoffman et al. point out, that it is "to the best of [their] knowledge" the first study to "have examined HMB supplementation in soldiers during intense military operations" (Hoffman. 2016).

Learn more about the potential beneficial effects of HMB at the SuppVersity:

HMB For Fat Loss?

Hica & HMB in Yogurt

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Breakthrough HMB Science

HMB + Whey = Useless?!

HMB Lower Body Fat, Higher T?

The authors examined the effect of 23-days of HMB supplementation on the immune and inflammatory response, and changes in muscle mass in combat soldiers during highly intense military training duringn which they consumed eiather with three servings (1 gram per serving) per day (at meal time | BetaTor®), or a placebo (PL) consisted of a similar amount of Litesse® polydextrose, reverse osmosis water, corn syrup, debittering agent, orange flavoring, stevia extract, citric acid, potassium sorbate, and xanthine gum powder (both sponsored by Metabolic Technologies Inc.):

• During the 23-day study period all soldiers performed the same daily protocol. 
• On days 1 – 10 soldiers were garrisoned on base and participated in the same advanced military training tasks that included combat skill development and conditioning. 
• During days 11 – 17 soldiers were released for a week of rest and recovery. Upon reporting back for duty, soldiers were then subjected to a week (days 18 – 23) of extreme training with minimal recovery. 
• On days 18 through 20, soldiers navigated 23.3 km per evening in difficult terrain carrying approximately 35 kg of equipment on their back (equating to approximately 40% of participant’s body mass). The duration of the navigational exercise lasted between 6 – 8 hours per evening. During daylight TED 
• On day 21-23, the soldiers were subjected to excessive physical training that included 90-min of intense hand-to-hand combat (krav-maga training), 60-min of endurance training and an additional 60-min of resistance training. 

As the scientists point out, the soldiers slept of only 22.5 h (3.8 ±3.0 h per night) during the six days of intense training, which including two evenings of no sleep (days 18 and 22). Blood draws and magnetic resonance imaging (MRI) measures were conducted in a single day prior to (PRE) and approximately 18-hours following the final supplement consumption (on day 24) (POST). All
blood draws and MRI measures were performed at Soroka Medical Center.

Table 1: Circulating cytokine concentrations (pg/ml) and muscle damage markers in HMB and PL in response to intense military training (Hoffman. 2016) | All data are reported as means ± SD.

Due to injuries and compliance issues, only 13 of the 27 participants were included in the final analysis (HMB = 6 and PL = 7), and even those subjects consumed only 89.3 ± 6.8% of the possible servings. I doubt, however, that the scientists didn't observe significant interactions were observed between HMB and PL for body mass (F=3.36, p=0.094) from pre (72.6 ± 7.1 kg and 70.7 ± 6.6 kg, respectively) to post (71.7 ± 6.4 kg and 71.2 ± 6.9 kg, respectively).

Why is HMB-FA supposed to be better than calcium HMB (Ca-HMB)? While some people say that the producers make false marketing claims about the bioavailability of HMB-FA, the reality is that the patent holder's claim that "BetaTOR [HMB-FA] is more rapidly absorbed so you get a higher peak and sustained concentration in the blood" (Manufacturer claim) has been proven in both, rodent (Shreeram. 2014) and human studies (Fuller. 2011). The former, however, also reveal that the bioavailability, i.e. the amount of HMB that actually hits the circulation - or, as scientists say the area under the curve (AUC) from t = 0 to t = ∞ - is actually 49%, 54%, and 27% lower (with increasing doses reducing the difference) than for Ca-HMB (Shreeram. 2014). The often-heard claim that the AUC doesn't matter as much as the speed may be in analogy to the comparison of whey vs. steaks, where the speed at which whey protein is absorbed and its leucine content enters your bloodstream is supposed to make all the difference, but is as of yet unproven.

On the other hand, the scientists observed potentially meaningful effects of HMB on markers of inflammation. More specifically, HMB ingestion, based on magnitude analysis (see Table 1 for an overview of all results), ...

• likely attenuated (78% likelihood effect) response compared with the effect of PL (a difference ± 90% CI of -38 ± 43.7 pg/ml between he Δ HMB – Δ PL)
• likely(87.2% likelihood effect) attenuated the INFγ response compared with the effect of the placebo (a difference ± 90% CI of -42 ± 47.3 pg/ml between the Δ HMB – Δ PL)
• possibly attenuated (74% likelihood effect) the IL-1ra response compared to PL (a difference ± 90% CI of -11 ± 18.9 pg/ml between the Δ HMB – Δ PL).
• possibly (74.5% likelihood effect) attenuated the IL-6 response compared to PL (a difference ± 90% CI of -6.6 ± 11.2 pg/ml between the Δ HMB – Δ PL).
• possibly attenuated (63% likelihood effect) the GM-CSF response compared with the effect of PL (a difference ± 90% CI of -8.1 ± 20.0 pg/ml between the Δ HMB – Δ PL).
• likely decreased (80.5% likelihood effect) the IL-8 response compared to PL (a difference ± 90% CI of -6.7 ± 10.0 pg/ml between the Δ HMB – Δ PL).
• very likely (92% likelihood effect) attenuated the TNF-α response compared to PL (a difference ± 90% CI of - 10.8 ± 7.2 pg/ml between the Δ HMB – Δ PL).

As the authors point out, "[t]he remaining cytokines demonstrated no significant pre and post changes between HMB and PL for IL-1b (F=0.04, p=0.84), and MCP-1(F=0.58, p=0.46) [and,  more importantly] the magnitude based inference analyses indicated that comparisons between HMB and PL on these inflammatory markers were unclear" (Hoffman. 2016).

Figure 1: There's a 77% chance the rel. increase in adductor magnus MRI muscle volume is significant (Hoffman. 2016). In view of the likely increased CK and LDH levels this could be a result of cell swelling in response to muscle damage.

Unfortunately, we have to eyeball the trend (F=4.30, p=0.062) towards HMB's effects on plasma CK with the same skepticism as the "likely", "possible" and even "very likely" effects on markers of inflammation. Ok, the fact that the increased CK levels in the HMB group were accompanied by "a likely increase (84% likelihood) in the LDH response compared to PL (a difference ± 90% CI of 53 ± 5.8 IU·L-1 between the ∆ HMB - ∆ PL)" (Hoffman. 2016), is what you'd expect in response to exercise. Usually, though, CK and LDH are considered markers of muscle damage and IIRC the scientists thought to demonstrate that HMB has a muscle protective effect.

To even complicate things, in previous studies both acute increases and chronic decreases in CK have been observed in studies by Wilson et al. (2009 | acute data) and Panton et al. (2000 | chronic data), respectively. Whether there was an increased muscle damage or whether HMB had protective effect as the "likely [...] increase muscle volume for the adductor magnus (77% likelihood [see Figure 1]) compared to PL" (Hoffman. 2016), the scientists appears to suggest, is thus impossible to say.

More HMB Free Acid Science: Now It's Also Good For High Intensity Interval Training (HIIT) Says the Latest Spon-sored Trial W/Out Calcium HMB Con-trol in Young Men & Women | more!

Bottom line: Even though I cannot debate that the scientists' magnitude analyses provide, as they say in the conclusion, "evidence that HMB supplementation may attenuate the inflammatory response to high intense military training, and maintain muscle quality" (Hoffman. 2016). The study is seriously under-powered (remember they had 14 dropouts).

Due to the high number of dropouts, it was more or less impossible to produce significant results. In a situation like that, the use of magnitude analyses to "save" the study makes sense, but reliability of the results is even lower than "likely" and "possibly" would suggest.

So why did I discuss the study, then? Well, let's say I sense that either Metabolic Technologies Inc., who are mentioned in the acknowledgements, which also declare that the authors have "no conflict of interests to report"(Hoffman. 2016), or licensees of HMB free acid are going to cite this study in write-ups and on product packages without mentioning words like "possibly" or "likely" or any of the other problems discussed above | Comment on Facebook! 

References:

• Fuller, John C., et al. "Free acid gel form of β-hydroxy-β-methylbutyrate (HMB) improves HMB clearance from plasma in human subjects compared with the calcium HMB salt." British journal of nutrition 105.03 (2011): 367-372.
• Hoffman, Jay R., et al. "HMB attenuates the cytokine response during sustained military training." Nutrition Research (2016).
• Panton, Lynn B., et al. "Nutritional supplementation of the leucine metabolite β-hydroxy-β-methylbutyrate (HMB) during resistance training." Nutrition 16.9 (2000): 734-739.
• Shreeram, Sathyavageeswaran, et al. "The Relative Bioavailability of the Calcium Salt of β-Hydroxy-β-Methylbutyrate Is Greater Than That of the Free Fatty Acid Form in Rats." The Journal of nutrition 144.10 (2014): 1549-1555.
• Wilson, J.M., et al. "Acute and timing effects of beta-hydroxy-beta-methylbutyrate (HMB) on indirect markers of skeletal muscle damage." Nutrition & metabolism 6.1 (2009): 1.

Normal-Weight Women Lose >6kg Fat Mass in 6 Weeks With Three 15x60s HIIT Workouts/Week - Without Dieting

Normal-Weight Women Lose >6kg Fat Mass in 6 Weeks With Three 15x60s HIIT Workouts/Week - Without Dieting

high intensity HIIT interval training LISS lose fat low intensity steady state

I am still waiting for a study using only body weight exercises like squats, push ups, burpees and co as a HIIT regimen for weight or rather fat loss.

While HIIT is gaining ground especially in male muscle heads, women like the twenty-three previously untrained women (28.43 ± 12.53 years), who participated in a recent study from the Department of Sport at the School of Physical Education and Sport of the University of Sao Paulo in Brazil (Panissa. 2016), are gravitating rather towards training in the alleged (but non-existing) "fat burning" zone at an intensity of 70% of their individual HRmax.

I guess, Panissa et al. knew that, because in their latest study they compared the effects of 6 weeks of high-intensity intermittent training (HIIT) to those of moderate intensity continuous exercise (MICT-control group) on body composition (skinfold measures), hunger and food intake.

Read more about exercise-related studies at the SuppVersity

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As previously highlighted, the subjects were twenty-three previously untrained women (28.43 ± 12.53 years) who were randomly assigned to a HIIT (n = 11) or MICT group (n = 12).

• The HIIT group performed 15 1-min bouts at 90 % of maximum heart rate (HRmax) interspersed by 30-s active recovery (60 % HRmax). 
• The MICT group performed a continuous exercise at 70 % HRmax equalizing the training load method proposed by Edwards (1993) to a similar value achieved by the HIIT group. 

Training for both groups was performed on regular cycling ergometers three times per week for 6 weeks. More specifically, both groups performed the same warm up and cool down, composed by 3 min at 60 % of maximum heart rate, MICT sessions consisted of moderate intensity aerobic exercise, i.e., after warm up the subjects performed 29 min at 70 % of maximum heart rate. HIIT group performed 22 min of HIIE using a 2:1 effort–pause ratio, where the effort was 1 min at 90 % of maximum heart rate and recovery was a 30s exercise at the same load as warm up (60 % HRmax).Each training session was closely supervised, and load was adjusted according to individual HR prescription. During this period subjects were asked to avoid any supervised exercise and strenuous efforts during their daily routine.

Was the training load standardized? To equalize training load between groups, the scientists used a method proposed by Edwards (1993). He proposed a zone based method for the calculation of training load. According to Edwards model, the time spent in five pre-defined arbitrary zones is multiplied by arbitrary coefficients to quantify training load. You can read up on the method here.

The performance effects were assessed by the means of Astrand cycloergometer that were used to estimate maximal oxygen consumption (VO2max) 1 week before and after the training period.

"Feeding behavior was assessed by two methods: (1) a 3 days daily food recordatory, including 1 weekend day before the protocols at baseline and after the last session. A detailed explanation for filling the food diary was held at the end of the evaluation, to be returned completed during the first week of training. The analysis of food diaries was made from the application to FatSecret [Subar. 2010]; (2) Immediately after each training session, participants answered a Visual Analog Scale (VAS) of Hunger ranging from 1 to 10, where 1 corresponded to no sensation of hunger and the 10 maximum feeling of hunger" (Panissa. 2016).

The subjects body composition was calculated based on detailed measures of skinfold thickness (triceps, subscapular, chest, supra iliac, abdominal, thigh and leg and the circumference of waist, hip, arm, chest, thigh) and legs - a method that is, assuming it is done correctly, as accurate as an expensive DXA-scan (Eston. 2005; Steinberger. 2005).

Figure 1: Relative changes in BMI, fat free mass (FFM), fat mass (FM) and waist circumference over the 6 week study; absolute changes in kg/m², kg and cm are displayed as first number below the bars (Panissa. 2016).

As you can see in Figure 1, both interval and steady state training induced significant pre- to post-decreases for fat mass, fat percentage, waist circumference and sum of seven skinfolds.

This is no "HIIT is better than LISS / MICT study! Theoretically, the study at hand "proves" that HIIT is more effective than LISS, but let's be honest: if you volume-equate HIIT and light / medium intensity training you end up at durations for the LISS / MICT of which no one would be surprised that they don't trigger fat loss. Plus: Facebook Fans know: HIIT decreases MICT / LISS increases appetite when all things are considered (more). Furthermore, the women were untrained and didn't do extra resistance training which would add additional load on the sympathetic nervous system and may thus (if done 3+ times per week) better be combined with LISS or MICT which would provide a parasympathetic stimulus that could ideally complement your resistance training training.

With a 2:1 fat to muscle ratio, the HIIT regimen was yet significantly more successful in improving the subjects' body composition (which obviously depends on the relative, not the total amount of fat) and that despite the fact that the energy intake didn't change significantly in either of the groups.

Figure 2: Daily energy intake in kcal before and during / after the exercise intervention (Panissa. 2016).

Another parameter that showed a measurable, albeit not significant inter-group difference is the effect of the exercise intervention on the subjects' fitness, as it can be predicted based on the subjects VO2max, a value that increased by a whopping 31.12% in the HIIT group, and only 16.70% in the MICT group - a difference that can hardly surprise the average SuppVersity reader.

Isn't HIIT for everyone? Study suggests: Effective- and usefulness of high intensity interval training depend on age and fitness level | learn more

Bottom line: HIIT wins, but not with a statistically significant advantage. As the authors point out, "the main result of the present study was that although the HIIT was able to promote a higher decrease in body fat mass" (Panissa. 2016). Furthermore, the observed benefits of HIIT were not, as previous studies had suggested, due to changes in hunger and energy intake. This important observation leads the authors to conclude that "the hypothesis that changes in hunger (measured by analogical visual scale in all training sessions) and in energy intake (measured by food diaries preand post-training) would contribute to a higher efficiency of HIIT to decrease body fat was not confirmed by our results" (Panissa. 2014).

What the scientists forget to mention in said conclusion, however, is that the lack of statistical significant differences may be a consequence of the "short term" nature of their study, they emphasized in the title "Can short-term high-intensity intermittent training reduce adiposity?" (Panissa. 2016). I bet: In a longer term and/or better powered follow up study, the already visible changes will achieve statistical significance | Comment!

References:

• Edwards S. "High performance training and racing." In: Edwards S (ed) High performance training and racing. Feet Fleet Press (2013), Sacramento, pp 113–12.
• Eston, R. G., et al. "Prediction of DXA-determined whole body fat from skinfolds: importance of including skinfolds from the thigh and calf in young, healthy men and women." European journal of clinical nutrition 59.5 (2005): 695-702.
• Panissa, Valéria Leme Gonçalves, et al. "Can short-term high-intensity intermittent training reduce adiposity?." Sport Sciences for Health (2016): 1-6.
• Steinberger, J., et al. "Comparison of body fatness measurements by BMI and skinfolds vs dual energy X-ray absorptiometry and their relation to cardiovascular risk factors in adolescents." International journal of obesity 29.11 (2005): 1346-1352.
• Subar, Amy F., et al. "Assessment of the accuracy of portion size reports using computer-based food photographs aids in the development of an automated self-administered 24-hour recall." Journal of the American Dietetic Association 110.1 (2010): 55-64.

Sodium Bicarbonate a Performance Booster for Only 66% of the Athletes? Study Shows Individual & Variable Responses from Zero to + 30% Increase in Maximal HIIT Workloads

Sodium Bicarbonate a Performance Booster for Only 66% of the Athletes? Study Shows Individual & Variable Responses from Zero to + 30% Increase in Maximal HIIT Workloads

baking soda bicarbonate high intensity high volume HIIT NAHCO3 performance sodium bicarbonate

Even though, the study at hand confirms that NaHCO3 doesn't work for everyone previous studies show it's worth trying.

You will probably have asked yourselves, whether I had already forgotten about sodium bicarbonate and the performance enhancing effects of pH buffers, right? No, I didn't, but unfortunately, many researchers have... well, many, but not all researchers. Gabriela Froio de Araujo Dias and her colleagues from the University of Sao Paulo, for example, have just released a paper in which they describe the intriguing results of the first bicarbonate study that was specifically designed to (a) determine within- and (b) inter-individual variation that could potentially compromise the magnitude of an effect that's determined based on averages (e.g. if you use bicarb three times and have performance increases of 0.4%, 5% and 0.3% it will look less effective).

You can learn more about bicarbonate and pH-buffers at the SuppVersity

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In the corresponding experiment, the scientists had 15 physically active males (age 25±4 y; body mass 76.0±7.3 kg; height 1.77±0.05 m) complete six cycling capacity tests at 110% of maximum power output (CCT110%) following ingestion of either

• 0.3 g/kg body mass of sodium bicarbonate (SB | 4 trials) or
• alcium carbonate placebo (PL, 2 trials).

Just in case you're wondering: Calcium carbonate has no reasonable buffering effect as it will not, as you can see in Figure 1 affect the pH, bicarbonate levels of base excess of the blood in the way bicarbonate does. It is thus the standard choice in corresponding experiments.

Figure 1: Line graphs for blood measurements (mean ± 1SD) at Baseline, Pre-exercise, Post-exercise and 5-min post-exercise. Panel A displays pH; Panel B displays bicarbonate; Panel C displays base excess; Panel D displays lactate. PL trials are represented by dashed lines and SB trials are represented by solid lines (de Araujo Dias. 2015).

As you may already know from previous SuppVersity articles on bicarbonate, the increases in blood pH, bicarbonate, base excess and lactate you see in Figure 1 are important to tell what exactly triggers the net effect of using baking soda as a pH buffer. What every athletes will yet be more interested in, though is whether the buffer allowed the recreationally active men who participated in the study saw statistically significant increases in the total work done (TWD) during the 110% high-intensity cycling capacity test, or not.

Learn more about Serial Loading!

You have problem "stomaching" NaHCO3? If you feelm, like some of the subjects in the study nauseated or even get diarrhea when you ingest a large bolus of sodium bicarbonate at once, try the Serial Loading Protocol from Dreher's 2012 study I discussed in an older SuppVersity article about sodium bicarbonate. That should work even for the most sensitive tummies. That's still no guarantee that it'll work, though, and would - just as the study at hand shows it for the regular bolus administration require some experimentation.

As you can see in Figure 2, the average subject saw the highest improvement in the last of the four trials (7%); an improvement of which statistics tell us that it says that there's 93% chance of general substantial improvement - with lower values for the other trials.

Figure 2: Rel increase (%) in total work (figures over the bars indicate likelihood of relevant benefits and relative increase, e.g. for bar 4: "It's 93% likely that the 7% increase displays a real-world relevant performance increase) - left; Total work done during SB trial as function of total work done during PLA trial - right (de Araujo Dias. 201).

Apropos "other trials", when the scientists removed the subjects who reported sick during trial 1 and trial 3, the results of trial 1 suggest a "likely" benefit (81%) and those of trial 3 a "possible" (50%) benefit. The notion that whether you benefit or not can / will depend on how well you tolerate the bicarbonate solution would also be confirmed by the data in Figure 2, right. The latter is a plot of the ratio of total work done in the sodium bicarbonate trial #4 vs. the control trial; a plot that easily tells us who saw benefits and who didn't because all "winners" are above, while all "losers" are below the transverse line. And since the distance to said line is a marker of the performance increase, you can also see that even among those who did benefit, the benefits ranged from hardly measurable as in subject #7 to a whopping 30% increase in total work done during the high-intensity cycling capacity test in subjects #12.

25g of Baking Soda Will Up Your Squat (+27%) & Bench Press (+6%) Within 60 Min | more

Bottom line: If you belong to the unlucky 33%, who were represented in the study at hand by the 5 subjects the scientists found who didn't benefit in any of the four sodium bicarbonate trials, you could probably still try the serial loading protocol and if that doesn't work either, simply accept that "SB may not always improve exercise" (de Araujo Dias. 2015).

On the flipside, though, you must not give up on baking soda if you didn't see improvements in your first trial, either. Eventually, the data from the study at hand also shows that even in those who benefit the benefit can sometimes be small or even non-existent.

As a trainer or trainee, you should thus keep in mind that sodium bicarbonate, baking soda or NaHCO3 must be taken on multiple occasions in order to categorize yourself or your clients into non-responders and potential responders and excellent responders | Comment on Facebook!

References:

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

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

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

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

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

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

Read more about exercise-related studies at the SuppVersity

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

  

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

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

  

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

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

  

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

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

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

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

  

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

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

  
  

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

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

  

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

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

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

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

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

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

References:

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