Tag: Fitness

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

HIIT Reverses Aging At a Cellular Level. Should We All Be Adding It To Our Exercise Programs and Turning Back The Clock?

High intensity interval training (HIIT) is one of today’s most talked about forms of exercise.  While the approach has been floating around gyms for a long time it has only been in the last few years that our colleagues in the research community have really begun to increase the amount of research being done in this area.  In 2012 when I attended the American College of Sports Medicine annual conference there was a session on HIIT research and the general attitude was that they had suddenly stumbled across an amazing new technique and were just starting to learn how it works.  This is the general flow of almost everything in the world of fitness and training.  A few coaches and trainers begin utilizing an approach, it theoretically makes sense and people seem to be making improvements and before you know it practitioner after practitioner are jumping on board and creating their own versions of it (many trying to sell their formula).  Once a certain critical mass is reached the research community begins to take notice and starts looking into the effectiveness of the approach.  They either quickly debunk it and move on or they find there is something to it and continue to do more and more research.  In the case of HIIT their early research was strongly in support of the approach and as the years have gone by the body of literature on the subject has grow quickly.  A scan of published studies on PubMed using the search term “high intensity interval training” comes up with 1,235 citations. Just in the first three months of 2017 there are 94 new studies and for 2016 there were 263.  I can promise you that if I tweaked the search terms a little or looked on another site for citations that we could increase those numbers.   Clearly there are far too many studies to do one simple deep dive into the research and draw a full understanding of it so with that thought in mind, I present to you the first installment of High Intensity Interval Training research.  I will do my best to curate the literature and pull out the pieces that are most relevant to front line coaches and trainers as well as everyday exercisers looking to maximize their health and fitness improvements.

The most recent HIIT study that has been getting considerable coverage from the mainstream media has the very digestible title “Enhanced Protein Translation Underlies Improved Metabolic and Physical Adaptations to Different Exercise Training Modes in Young and Old Humans”.  Sounds very exciting doesn’t it?  Well that is exactly the type of attention grabbing headline you expect from that newsstand favorite, Cell Metabolism.  Now the headlines that most popular media are using for this article tend to be along the lines of “HIIT Training, The Fountain of Youth”.  While that may be a bit of hyperbole, that title is far more along the lines of what this study actually suggests is happening at the cellular level.

Robinson et al.(2017) examined and compared a variety of responses to high intensity interval training, more traditional strength training and a combination of the two (both performed at a lower intensity and volume then the individual test groups).  The authors went one step farther in that they used both a young group of subjects (18-30 years) and an older group (65-80).

Subjects in the HIIT group trained 3 days per week on a cycling ergometer for 4 x 4 min at greater than 90% of peak oxygen consumption (VO2  peak) with 3 minutes pedaling at no load in between sets.  They then walked on a treadmill 2 days a week for 45 min at 70% of VO2 peak.  The resistance training (RT) group per formed 4 sets of 8-12 repetitions of a series of both upper and lower body exercises twice a week.  The combined training (CT) group underwent a 12-week sedentary period followed by 12 weeks of cycling 5 days a week for 30 minutes at 70% of VO2 peak and resistance training 4 days per week with less repetitions then the RT group used.

Cardio Respiratory Fitness, Muscle Mass and Insulin

Let’s begin reviewing the results with the easy and to be expected outcomes.  The youngsters saw significant increases in absolute VO2 peak for all three training approaches, the greatest results with HITT leading the way followed by CT and then RT.  For relative VO2 peak the young group saw an approximate increase of 28% with HITT, 17% with CT and no statistically significant change with RT.  The older subjects saw absolute VO2 peak increases for both the HITT and CT group.  They did see improvements with RT but the results were not statistically significant.  Absolute VO2 peak increased 17% for HITT and 21% with CT.  There were no significant changes for RT.  For the non-science geeks, remember VO2 peak refers to the top rate at which your body utilizes oxygen and a bigger number is better, so big props to the older group for such significant changes.

All three training groups for both age cohorts saw increases in fat free mass (that means added muscle mass).  As expected resistance training had the greatest impact and more so for the younger group but the results were positive for everyone in all conditions.  Leg strength increased for the RT and CT groups in both age categories but not the HITT group.  This could be to the specificity of training for the cycling group.

It is well known that insulin sensitivity is improved with exercise.  This means the body does a better job of responding to the presence of insulin and moving glucose from the blood stream into storage as glycogen.  The younger group of subjects saw improvements in insulin sensitivity for all three training categories.  The older subjects saw improvements for both HIIT and RT but not the combined training.

Mitochondrial changes

Let’s start by remembering that mitochondria are the power factories in your cells.  The more you have and the better they work the more ATP (ATP = energy molecules) you can produce and the more work you can do.  Also keep in mind that mitochondria are primarily associated with aerobic metabolism (with oxygen = cardiorespiratory fitness).  It is common for people to have reduced mitochondrial content and function with age and while this study is not looking at the causes for these declines with age, it’s fairly safe to say it is both a simple function of aging and also a result of a function of detraining for most individuals.  And while we are not touching on this subject today, do note that mitochondria are exceptionally complex structures that do far more than just produce ATP.

The authors found that with HITT the younger subjects had a 49% increase in mitochondrial respiration and the older subjects had an outstanding 69% increase.  Yes you read that correct, a 69% increase in their ability to produce energy, pretty amazing.  With the CT group the younger subjects saw a 38% increase but the older subjects did not.  Neither group saw improvements with RT suggesting that people need some form of cardiorespiratory stimulus different from resistance training to achieve these benefits.  Both HITT and RT resulted in increased in mitochondrial protein content for older adults explaining some of the improvements that they experienced.  It would be interesting to see a similar study conducted that used high intensity intervals done with various resistance training exercises to determine if those movements could generate similar mitochondrial changes as well as how different types and volumes of HITT influenced results.

Exercise effects on skeletal muscle gene expression

A gene is a set of instructions encoded on our DNA.  On its own it doesn’t do anything but if it is “expressed” it is turned on in such a way that a copy of those instructions are made and sent to other parts of the cell for its function to be carried out, usually the creation of a protein or other molecule that has a particular job in the cell.  Remember that not every gene expression and function they impact is positive and some can be involved in issues like cellular death or uncontrolled reproduction (cancer) so in some instances we want to see certain genes down-regulated while would like an increase in activity of others resulting in positive impacts on the cell and general body.

The authors refer to particular gene sequences that are turned on or off as gene transcripts.  Looking at transcription in skeletal muscle related to mitochondria, muscle hypertrophy (growth) and insulin sensitivity before training, the older subjects had 267 gene transcripts lower and 166 higher than the younger group.  That represents quite a significant difference in gene activity with age.  Following training the largest numbers of genes were turned on with HITT in both young and old subjects.  Compared to HITT, RT and CT increased 35% and 28% fewer genes in the younger subjects.  In the older subjects 70% and 84% fewer genes were expressed compared to HITT.  Score another one for older adults performing HITT.

In young subjects 274 unique genes were increased by HITT, 74 by RT and 170 by CT.  Older exercisers had 396 genes increased by HITT, 33 by RT and 19 by CT.  Both age groups clearly show the most gene activity as the result of HITT and this does not even count genes that were affected by more than one training mode.

The next question was how many of the genes affected are impacted in both the young and older group and how many are specific to age.  Of the total 553 genes affected by HITT in older subjects (157 had some overlap with RT/CT so 157 + 396 unique HIIT genes = 553), one –third (181) were also shared with the younger HITT group and the young RT and CT groups shared 114 of these genes. A full third of the older HITT genes (186 of 553) were unique to the older group suggesting that a large number of the genes impacted by HITT are age specific.

Impact of training on skeletal muscle proteins

When someone says protein most of us conjure up images of steaks and chicken breasts and post workout shakes, thinking of the macronutrient we all eat to survive.  Yes protein is something we eat and we all know that our bodies use it to produce muscle but at the cellular level a variety of proteins are being constantly produced and they have an assortment of functions, acting as catalysts, signal receptors, switches, motors and more.  As we previously mentioned, many of the gene transcripts that the researchers examined are turned on by different types of exercise and when they are expressed, many of them instruct the cell to build a particular type of protein depending on the gene.

The younger subjects in this study saw increases in protein abundance for 265 proteins following resistance training.  They saw 114 proteins increase following HIIT.  Only 35 of the proteins that increased were affected by both the RT and HIIT.  In the older subjects 147 proteins increased in abundance following RT and 227 increased following HIIT.  Only 38 were shared between the two types of training.  This suggests both significant impacts of the different types of training as well as the very large impact that HIIT has on older adults.

Looking at only mitochondrial proteins, the younger subjects had 141 increases with RT and only 25 with HITT while the older subjects increased 53 mitochondrial proteins with RT and 169 with HIIT.  Again very high rates for both types of training for older adults, especially with HIIT.

Study limitations

This was a very well conducted study but like all research, there are limitations.  There were a limited number of subjects and after they were broken down into three different training protocols for each age group that resulted in a fairly small number of subjects in each group.  The depth of cellular testing that was done was significant and produced meaningful results that do suggest these benefits can be achieved by the broader population but there is always a limit to how far we can extrapolate the results with a small study population.  There was also a fairly strict exclusion criterion so the individuals who were ultimately selected were extremely healthy to begin with.  That leads to the immediate question of how individuals with an assortment of medical conditions would respond to the same training protocols.

There are also issues regarding the training protocols used.  For the resistance training group, they were given what seems to be a very traditional basic plan that isn’t necessarily reflective of the type of training most people are doing in gyms today.  No low rep heavy work.  No resistance training based intervals or combinations that are designed to raise heart rate and present a metabolic challenge.  It would be interesting to see how more modern resistance training techniques fared.  The current trend for “metabolic” training and short rest times could produce results more similar to what we consider pure cardio intervals like biking and running.

For the HIIT intervals, what affect do different time intervals have?  Thirty seconds versus a minute versus the four minute bouts used in this study.  What about different volumes? Surely there has to be differences when those variables are changed.  How many intervals do we need to maximize benefits and what is the optimal time of those intervals?  Also, what about different types of stimulus, running or rowing as opposed to biking?  And what happens at lower levels of intensity?  Certainly not everyone can get out and start working at 90% VO2 peak and many people will never be able to train at that level for a variety of reasons.

Obviously no one study can answer everything but this study clearly adds to the body of literature that says HIIT really does something different in the body as compared to other forms of exercise and is worth continuing to ask these questions and investigate these issues.

So there you have it, HIIT increases VO2 peak, insulin sensitivity, mitochondrial respiration, muscle mass and strength in both young and old subjects with really remarkable improvements in older adults.  And while resistance training is great, it doesn’t impact the cardiovascular related elements in nearly as meaningful a way.  Not only does HIIT have those affects, on the cellular level it greatly increases gene expression and positively impacts regulation of muscle growth, mitochondrial pathways and protein synthesis.  Now get out there and start adding some HIIT training to your programs and keep thinking about all those amazing changes that are happening at the cellular level as a result.

Works Cited

Robinson, M., Dasari, S., Konopka, A., Johnson, M., Manjunatha, S., Esponda, R., Carter, R., Lanza, I., Nair, K.S., (2017). Enhanced Protein Translation Underlies Improved Metabolic and Physical Adaptations to Different Exercise Training Modes in Young and Old Humans. Cell Metabolism 25, 581-592.