How HIIT impacts untrained men, overweight women and elite endurance athletes.

A few weeks ago I wrote about a study that highlighted a number of significant changes on the cellular level produced by high intensity interval training.  If you take that study on its own, HIIT sounds like the best thing to hit the exercise world since the invention of sneakers.  Of course we know that any given study can only look at a few very specific parameters and you have to take the results in context with a much larger body of study.

The results were so intriguing from the first study I reviewed that I couldn’t help but start to ask an assortment of questions about HIIT training.  What is the best combination of work and rest intervals and what differences exists when using different interval/rest times?  What differences then exists between different types of intervals: running, biking, rowing, weight lifting, body weight exercises and so on?  How do different populations (men vs. women, young vs. old, sedentary vs. active, endurance athletes vs. strength athletes) react to different types of interval training? What are the differences between interval training and other forms of training (traditional strength training, endurance training, etc.)?  How does interval training impact individuals with various medical conditions such as diabetes and obesity and how are those impacts different then other forms of exercise?

So here we go with the first of what will probably be many follow up articles about various aspects of high intensity interval training.

Steady-state and moderate intensity intervals can be just as good as HIIT in untrained individuals

Let’s begin by going way back to 2015 and a study by Foster et al. (2015) in the Journal of Sports Science and Medicine.  Relatively inactive young adults were put into either a steady-state training group, a very high intensity-brief interval protocol (Tabata) or a moderate intensity –moderate time interval (Meyer).  The steady state group cycled for 20 minutes at a moderate to vigorous intensity.  The Tabata group cycled for 20 seconds of intense work then 10 seconds of unloaded cycling for 8 sets, equaling a total of 4 minutes.  The Meyer interval group did 20 minutes of cycling consisting of 13 sets of 30 second work intervals followed by 60 seconds of active recovery.  Each group performed three workouts per week for 8 weeks, totaling 24 exercise sessions.

All three groups showed significant improvement in measures of aerobic and anerobic capacity however, there were no significant differences between the groups, suggesting that in relatively inactive young adults it doesn’t really matter which approach is used.  All three groups did increase the intensity at which they worked out over the course of the study and even the steady-state group was cycling at a fair degree of difficulty but overall, this study does not support the increased value of high intensity work for this population.

Usually most research studies are more concerned with the physiological impact of whatever they are testing but in this study the authors did start to take into account a factor that really comes into play in the real world, the psychological motivation of exercisers. How much they really enjoy a particular form of exercise and how likely they are to actually do it.  We can come up with the world’s greatest form of exercise but if it is so miserable to do only a tiny number of people will actually perform it and for the majority of people who need to exercise, the approach is worthless because they won’t do it.

In this study, subjects’ enjoyment of all three forms of exercise went down over time but significantly more so for the Tabata group.  While many people may find a moderate intensity interval approach more interesting than a steady state approach, the very high intensity intervals may just be too much for many members of the general public, especially those who have been more sedentary.  Yes high performing individuals may need the stimulus of very high intensity intervals to elicit improvements but for the majority of people it is probably not that crucial.  And ultimately we need people to want to continue to participate in exercise over time to truly gain the benefits and if their level of enjoyment is so low due to the discomfort of very high intensity intervals they are much more likely to stop exercising and not enjoy any of the benefits.

This also carries over to the time benefits of HIIT.  While a HITT workout can be completed in a reduced period of time, if by the time participants feel recovered enough to go on with their day they have needed as long as participants who engaged in longer duration more moderate to vigorous exercise sessions then there is no net benefit to the shorter duration period of exercise.  In this study the Tabata group needed so long to recover they didn’t see any time saving benefit as compared to the other two groups.  Keep in mind the Tabata subjects were exercising at a very high intensity.

So there you go, if you are working with or are someone newer to exercise you do have to put some real effort into what you are doing but you don’t have to go all out with extremely high intensity intervals to elicit many of the same benefits.  At least until you read HITT Reverses Aging At a Cellular Level.  I’ve got a nagging feeling that despite the important observations about participant behavior in this study, we are going to find a lot of data in future articles that continues to support higher intensity intervals.

HIIT improves body composition, strength, aerobic capacity and quality of life in overweight women

Now that we’ve taken a peak at young sedentary subjects let’s see what impacts HIIT has on a population of women with a little more to love.  Sperlich et al. (2017) studied women ages 18-35 who had body mass indexes (BMI) of 25 or higher, categorizing them as overweight, who had not been exercising for the previous six months or longer.  What is most interesting about this study is that instead of building intervals around traditional cardiovascular exercises, the authors developed interval circuits consisting of body weight exercises such as burpees, push-ups, lunges, squats and sprints.  The intervals used look far more like the type of HIIT circuits that are being used by personal trainers and group exercise instructors in classes at gyms and training facilities.

The subjects were broken down into two groups.  One group (HITT) performed three interval workouts per week for 9 weeks while the other group (Combined) performed the same workout twice a week and one low-intensity higher-volume cardiovascular workout consisting of jogging and walking.  The authors theorized the participants in the Combined group would experience some different cardio-respiratory and metabolic changes along with higher perceptions of quality of life.

Subjects in both groups saw similar decreases in weight, BMI, waist-to-hip ratio and fat mass while also seeing similar increases in fat-free mass (=muscle).  Ratings of perceived exertion for both groups went down over time in a similar manner.  Cardio-respiratory measures were all similar with the exception of peak oxygen uptake which was improved to a greater extent I the HIIT group.

Strength and related performance measures which consisted of push-ups, burpees, one-legged squats, timed skipping and counter-movement jump height all improved for both groups with no differences between groups.  The HIIT group did see a higher increase in the number of leg levers they could perform.

For all quality of life measurements both groups showed similar results with the exception of the HIIT group reporting higher perceptions of pain while the Combined group reported enhanced perceptions of general health.

So, if you are more concerned with getting the most possible improvement in VO2max in this population you should do 3 HIIT workouts but if you are more concerned with participants’ perceptions of general health and less discomfort you might want to lean towards a combined approach that replaces one HITT workout with some jogging and walking.  Either way, both approaches appear to be very beneficial for overweight women (at least under 35) and it’s safe to say this study supports body weight resistance exercise based high intensity intervals.

Polarized training vs HIIT vs threshold vs high volume training in elite endurance athletes

Up to now we have mostly looked at the effect of HIIT on less experienced or untrained individuals.  While the results there are positive with HIIT there are arguments for other forms of training.  When it comes to very experienced individuals and elite athletes all previous claims are off.  Their bodies are already highly adapted to training and under a tremendous amount of stress.  How they respond to certain stimulus can be totally different then untrained individuals.

Stoggl and Sperlich (2014) attempted to answer some of the questions regarding different training approaches for elite endurance athletes.  They began with the concept that endurance athletes use some combination of four training approaches.  The first and most common is the more traditional high-volume training (HVT) done at a lower intensity that is usually less than 80% of max heart rate, 65-75% of peak oxygen uptake (VO2peak) and at lower blood lactate levels.  The second approach is training at or near the blood lactate threshold (THR).  The third approach is HIIT training and the fourth is polarized training (POL) that uses some combination of the other three approaches.

Utilizing international level competitors in cycling, triathlon, running and cross country skiing the authors had the subjects train for 9 weeks under one of the four conditions.  They attempted to design workout protocols that resembled what these athletes would actually do for their normal training.  Five key performance variables were measures: VO2peak, velocity/power output at the lactate threshold (V/Plt), work economy, peak running velocity or power output (V/Ppeak) and time to exhaustion (TTE).

Their first interesting finding was that the only training approach that resulted in subjects losing a significant amount of weight was HIIT.  This is despite the HIIT group having less volume in their training then the other three groups.  While elite endurance athletes often are trying not to lose any additional body mass when they are in need of manipulating their body composition we can see that HIIT may be a useful training approach.

When it came to VO2peak the polarized group far and away had the greatest gain at 11.7% followed by HITT at 4.8%.  Work economy improved the most following HIIT while work economy expressed as a percentage of VO2peak improved only following polarized training.

The greatest improvement in time to exhaustion was found in the polarized group, almost double the next best approach, HIIT.  Peak velocity and power improved the most with polarized training followed closely by HIIT.  Both significantly better than the other two approaches.  Velocity/power output at lactate threshold also showed the greatest gains with polarized training again followed by HIIT.

Clearly in this population of highly trained athletes a combined training approach that includes HIIT showed the greatest improvements in performance variables that generally equate to success in ones sport.  So while we might argue for a higher percentage of HIIT in the less trained individual and someone who’s primary objective is weight loss, for more elite athletes we can see HIIT is important for performance improvement but needs to be integrated with other training techniques.  There seems to be a multiplying effect in results when HIIT is integrated with other techniques.

So there you go.  Three distinctly different groups, inexperienced younger adult males, overweight adult females and elite endurance athletes.  All three can benefit in some meaningful way from HIIT but we need to balance the unique demands and psychology of each group.  While elite athletes can handle the high intensity aspect of HIIT, for other groups it may be wise to utilize some work done at more moderate intensities to make the exercise more enjoyable and increase the likelihood of someone sticking around long enough to make significant changes.  We also saw that with our non-endurance athlete groups that interval circuits made up of body weight exercises seem to produce meaningful results.

Works Cited:

Foster, C., Farland, C., Guidotti, F., Harbin, M., Robers, B., Schuette, J., Tuuri, A., Doberstein, S. and Porcari, J.  (2015) The Effects of High Intensity Interval Training vs Steady State Training on Aerobic and Anaerobic Capacity.  Journal of Sports Science and Medicine. 14: 747-755.

Sperlich, B., Wallmann-Sperlich, B., Zinner, C., Von Stauffenberg, V., Losert, H., Holmberg, H. (2017) Functional High-Intensity Circuit Training Improves Body Composition, Peak Oxygen Uptake, Strength, and Alters Certain Dimensions of Quality of Life in Overweight Women.  Frontiers in Physiology. Apr 3;8:172

Stoggl, T. and Sperlich, B. (2014) Polarized training has greater impact on key endurance variables than threshold, high intensity or high volume training.  Frontiers in Physiology. Feb 4;5:33

The Best of This Month’s Strength & Conditioning Research: Time off from Training Spares Gains, Increased Athletic Performance with Contrast Movements and Variable Resistance Leads to Greater Strength and Power Gains.

I know, you mean to keep up with the latest research and read a few of the top journals every month.  You really do mean it but then work happens, and eating, and sleep, not to mention finding time to train.  Well don’t worry, I’ve got you covered here at FitnessBreakdown with a few quick summaries of some of the most interesting and applicable research being published.  That’s why you’re reading this blog anyway, it’s much easier to let us do the dirty work and sort through the hundreds of articles published every month to find the pieces of information that make a difference to your everyday work or training.  This week some highlights from the April 2017 issue of The Journal of Strength and Conditioning Research.

Short breaks in training do not lead to losses in strength and body composition

Hwang et al. (2017) examined the impact of a 2 week detraining period following a 4 week training period, with a second 4 week training period taking place after the break.  The authors were primarily interested in the impact on muscle strength and cross sectional area (hypertrophy) and how they differed through the training cycle.  Specifically how training gains in strength and mass occur at a greater rate in the early part of training and with a longer training period the gains occur at a slower rate.  The authors hypothesized that if subjects trained for four weeks with the faster rates of improvement and then took a 2 week training break that in the next 4 weeks they would experience the same faster gains that originally occurred as opposed to the slower rate of improvement that is seen with longer term training.  Essentially, does a train-rest-train approach allow for faster overall improvements as opposed to a longer term train-train-train approach?

The authors also used a group that was supplementing with 25g of whey protein post workout and a control group that used a carbohydrate supplement.  Over time they found increases in leg press strength after the training period, the detraining period and the retraining period. They did not note a significant difference between the different training periods or between the groups. There were no significant difference in body composition, lean mass, fat free mass or rectus femoris cross sectional area.  There was no evidence that a break in training resulted in faster gains when training is resumed.

While there were no earth shattering results from this study there was a key takeaway.  The two week detraining period did not result in any reduction in strength, muscle cross sectional area or lean mass.  This suggests that with well-trained individuals it is safe to take short breaks in training without worries about losing the improvements that were gained during the training period.  Many hard training individuals are afraid to take time off and allow their body a fuller recovery period and this study supports the benefit of regular short detraining periods, especially considering the small but positive improvements that happened during the detraining period.  Keep in mind this study used young males who were experienced in training and worked out four times per week.  The results may not hold true for older populations and those who train on a less regular basis or at lower intensities.  There is also a question of the length of detraining periods and the benefit sparing effect of a two week break on this population cannot be extrapolated too much longer detraining periods.


In-season strength training, especially with the addition of contrast movements improves athletic performance in youth soccer players

With the multitude of training approaches available it can become difficult for today’s strength coach to determine which philosophy to follow in order to maximize performance of their athletes.  This is further complicated by the different demands athletes face throughout the year in regard to what aspect of the training season they are in (preseason, in season, post season, off season). Hammami et al. (2017) attempted to partially answer this question in a study of in season junior male soccer players.  Specifically they were comparing the effect of pure resistance training program as opposed to a contrast strength program (and a control group) on a battery of athletic performance measurements.

The study lasted for 8 weeks and took place during a competitive season when the athletes were practicing 4-5 times per week and playing one competitive match.  The strength training group replaced a portion of their regular training time with program that consisted of back half squats to 90° utilizing weights that were 70-90% of their 1 rep maximum.  This program was performed twice per week.  The contrast strength training group performed the same squat program but for the first 4 weeks of the program, after every set of squats they performed 3 consecutive countermovement jumps with aimed arms.  During the second 4 weeks of the program the contrast strength group preformed 1 countermovement jump with aimed arms immediately followed by a 15-meter sprint.

Athletic performance was tested through 8 different measures that included 40-meter sprints, 4×5-m sprints, 9-3-6-3-9 meter sprints with 180° turns, 9-3-6-3-9 meter sprints with forward and backward running, repeated shuttle sprints, repeated change of direction, squat jumps and countermovement jumps.

In all measurements except the repeated shuttle sprint ability the strength training group and the contrast strength training group showed significant improvement as compared to the control group.  In the repeated change of direction test and the 4×5 meter sprints the contrast group showed significant improvement as compared to the standard strength group.  In all of the other tests both experimental groups showed similar improvements though with a non-statistically significant but still measured difference favoring the contrast training group.

So what is the take away?  First, an in-season strength program completed twice a week improved actual performance measures that should translate to increased advantages in competition.  Secondly, while both training approaches work well, the contrast training plan appears to have advantages and is easily implemented.  Third, the strength training programs both consisted of nothing more than squats or squats plus the contrast movements.  In today’s You Tube/Cross-Fit influenced training world of more volume, high intensity and creative mixes of movements a very simple, straight forward training plan improved performance.  The pressure on strength coaches to integrate these new influences in training programs is significant and perhaps in some cases counter-productive.  Sometimes a simpler, more classical approach may work better. Though that is a subject for other studies.  Considering this study was conducted on in-season athletes who are already under tremendous demand both on their time and recovery abilities, a lower volume, simpler program may be more appropriate and productive.

Variable resistance increases upper body strength and power more than traditional training

Today it is not uncommon to walk into a gym and find someone slinging up large elastic bands or chains over their squat or bench press bar.  Sure it looks like the person knows something that you don’t but are they really onto something or is this just another adventure in being creative trumps actual science?  Well in this case they are actually onto something that can be beneficial for certain training populations.

Riviere et al. (2017) compared variable resistance training to traditional resistance training and measured strength and power adaptations in elite youth rugby athletes.  Both groups underwent an identical resistance training program twice a week with the first workout emphasizing strength and the second workout emphasizing power.  The only difference between the two subject groups was that the variable resistance group used elastic bands equal to 20% of the prescribed load on their bench press.

The researchers measured 1 repetition maximum (1RM) in the bench press along with mean velocity and power at 35, 45, 65, 75 and 85% of 1RM.  After six weeks of training the subjects were retested.  Both groups improved their 1RM but the variable resistance group showed greater results.

For mean velocity measurements the variable resistance group showed small improvements at 35 and 45% of 1RM, medium sized changes at 65% and large improvements at 75 and 85% 1RM.  The traditional training group only showed small improvements at all levels of resistance.

Results for mean power were similar to the velocity measurements with the variable resistance group showing smaller changes at the lower levels of resistance and greater improvements at higher resistance levels.  The traditional group saw only trivial improvements in absolute mean power at all resistance levels and for relative power saw trivial changes for all levels except 85% 1RM where the changes were considered small.

So what does this all mean?  Both groups did improve their bench press strength, velocity and power but the variable resistance group clearly had larger improvements, especially at higher levels of resistance in the velocity/power measurements.  This supports the results of other studies that showed strength benefits utilizing variable resistance were greater than with traditional training though this was, according to the authors, the first study to look at power under these circumstances.

The authors offer 4 possible reasons for why variable resistance resulted in greater improvements.  1) During the eccentric phase there is an increase in the storage of elastic energy within the body which can be tapped into during the concentric portion of the lift which could result in more training stimulus leading to the gains. 2) The point at which the movement arms are at peak mechanical disadvantage, the sticking point, is the limiting factor in force production and how much resistance can be utilized.  Variable resistance can be used to work around this sticking point so there is more muscle tension during the later stages of concentric portion of the lift. 3) Normally there is a deceleration phase at the end of the concentric portion of the lift which is overcome with a greater constant acceleration through the entire movement when variable resistance is used.  This constant acceleration through the end of the lift can add to greater strength and power.  4) Variable resistance training forces more neuromuscular adaptations including the recruitment of larger motor units in the eccentric portions of the lift.  Collectively these factors lead to greater changes over time.

The greater improvements in velocity that occurred at higher levels of resistance may have been because the subjects used higher levels of resistance during their actual training protocol.  This allowed the subjects to show greater improvement at testing levels closer to their training resistances and smaller changes at resistance levels they did not train near.  The variable resistance group also showed larger differences in power then the traditional group as the resistance levels increased.  This is most likely because of the increased gains in velocity the variable group experience at higher resistance levels which allowed them to produce more power at those same resistance levels.

Now that we’ve established that variable resistance appears to offer increased improvements over traditional training, at least in the bench press, let’s put the brakes on before you rush out and start wrapping elastic bands around all of your bars.  First, the study had a very small population and only used one lift with variable resistance.  As we all should know by now, studies with small populations have only so much power and may not hold true for all circumstances, groups and other variations in training.  Secondly the study was done elite youth rugby players.  This means they are young, healthy, and participate in a sport where increased upper body strength and power is related to performance.  While it is probably safe to say that other trained athletes can experience similar results this doesn’t mean every personal training client in the gym should suddenly be using variable resistance in this way.

I want to shake my head and scream every time I see a less experienced and educated trainer putting an inexperienced, older or relatively unstable and weaker client under a bar with bands attached to it just because they saw one of the stronger, more experienced trainers in the gym using this technique in their own training.  Even worse, when a more experienced trainer shares the technique without really understanding it and with more concern about how they look to their younger colleagues instead of what is best for a particular client.  If someone cannot do a few sets of great body weight pushups and already do a bench press with a respectable level of resistance they probably should never be using variable resistance until they have already developed a great strength base with traditional training techniques.

Note that the elastic resistance used was equivalent to 20% of the prescribed training load. This means the subjects weren’t trying to use exceptionally challenging level of variable resistance.  They wanted enough resistance to enable the desired adaptations but not so much that the focus of the lift became dealing with the variable resistance levels instead of maintaining great form and focusing on the overall lift.  It would be very interesting to see a study that compares different percentages of variable resistance but I would hypothesize that after a certain point we would see reduced benefits.  It doesn’t take a lot of variable resistance to work around the sticking points and provide greater acceleration at the end of concentric lifts.  I would strongly suggest until we have a body of literature suggesting otherwise that if someone uses variable resistance they choose lower levels of resistance and limit themselves to something in the neighborhood of 20-25% of their total load.  Certainly if they are training at total loads closer to their 1RM.

Works cited:

Hammami, M., Negra, Y., Shepard, R., Chelly, M. (2017) The Effect of Standard Strength vs. Contrast Strength Training on the Development of Sprint, Agility, Repeated Change of Direction and Jump in Junior Male Soccer Players. Journal of Strength & Conditioning Research. 31:4: 901-912

Hwang, P., Andre, T., McKinley-Barnard, S., Morales Marroquin, F., Gann, J., Song, J., Willoughby, D. (2017) Resistance Training Induced Elevations in Muscular Strength in Trained Men Are Maintained After 2 Weeks of Detraining and Not Differentially Affected by Whey Protein Supplementation. Journal of Strength & Conditioning Research. 31:4: 869-881.

Riviera, M., Louit, L., Strokosch, A., Seitz, L. (2017) Variable Resistance Training Promotes Greater Strength and Power Adaptations Than Traditional Resistance Training in Elite Youth Rugby League Players. Journal of Strength & Conditioning Research 31:4: 947-955