Sometimes High Intensity Interval Training Isn’t The Solution

“Jill! That’s two!” She knew that meant the conditioning test was over for her that day.  She walked with a slight limp toward her water bottle at the other end of the court, shaking her head and mumbling something to herself.  There was only one teammate that achieved a better score, but Jill had dropped out of the conditioning assessment relatively early in comparison to previous efforts.  Now she was critical of herself.

The Coaches had watched the test.  Some thought Jill was out of shape from taking it too easy over the summer break.  They also noticed how Jill didn’t look fluid running – very labored. 

Jill was the best player, Captain, and arguably the hardest worker amongst the team on and off the court.  There aren’t many collegiate athletes that check off all of those boxes simultaneously.  So she earns leeway with Coaching Staff, and there wasn’t an overreaction to add extra sprints to practices… at least at that moment. 

Jill also is the type to be labeled as “tough” in the traditional sense because she was willing to play through pain and discomfort.  However, she was also quite stoic and wouldn’t voice concerns.  This made it challenging at times to encourage her to seek treatment or help her take care of herself.  She often came close to digging a hole she wouldn’t get out of.  Fortunately, we had mutual trust and respect.  So Jill would listen and attempt my input to see the outcome even when it didn’t fit typical paradigms of fitness training.

I spoke with Jill about how she trained over the previous summer.  She was very active, as most assumed she would be.  However, all of her conditioning, in addition to playing basketball, was focused on running repeated shuttles lasting twenty-two seconds to a minute in length – very common among basketball players.  Her conditioning test performance wasn’t a lack of effort or a commitment problem.  In fact, I was leaning more toward a too much of a supposedly good thing problem.  A very common issue with basketball players, and any athlete or fitness enthusiast eager to make gains.

We agreed Jill would monitor her resting heart rate each morning for the next two weeks.  This is by no means a perfect assessment of her needs, but it provided a clue to investigate.  She was in the 65 bpm to 72 bpm range.  “Is that good?” Jill asked.  “I think it’s a piece of information we can utilize,” I replied.

Conditioning Overview

Resting heart rate can simply be viewed as the efficiency of the heart to move blood.  Many stressors can impact resting heart rate: fear, anxiety, poor sleep, sickness, etc.  That is why it is not a perfect assessment.  However, resting heart rate may also provide evidence to how well someone fuels her activity utilizing oxygen through the aerobic energy system versus the short term energy systems that don’t rely on oxygen.  The aerobic energy system and the short term energy systems all work simultaneously to create the fuel humans need. 

The aerobic system is constantly working, but it’s primarily emphasized for sustained efforts lasting more than a couple minutes, and to help recover between high intensity efforts.  The short term energy systems are predominately for immediate to approximately 90 seconds of max effort work.  A shift in emphasis of each system’s contribution to the job at hand occurs based on the individual’s physiology and the task.  Basically, the higher heart rates for a given activity the more likely the reliance on short term energy systems.

All the energy systems are constantly working. We have to determine which one we are biasing, and if that is what we want (Franchini, 2016).

Too Much of a Good Thing

Focus on high intensity conditioning is very common amongst athletes, but also the general population.  Athletes, fitness professionals and Sport Coaches have made many conditioning drills based on things like the shot clock in basketball or the duration of an average shift in hockey (However, they fail to notice the fluctuations in speed and intensities during those periods).  The general fitness population are told high intensity interval training will burn fat the fastest, or improve your conditioning the fastest.  There is also the allure of the short amount of time to complete high intensity intervals, and the satisfaction of completing a challenging task when they are complete; aka we only “work hard” when we feel the burn and then maybe vomit in our mouth a little bit. 

High intensity interval training serves a purpose and can be very useful.  The physiological changes will help you improve power and sustain power for the time intervals you use.  High intensity interval training is also beneficial to help us become accustomed to the acidic environment created from repeated high intensity sprints.  Without experiencing this acidic buildup from conditioning, we would fatigue quicker.   However, focus on these intervals my hinder some people’s ability to recover between repeated sprints or between training sessions if the aerobic system is underdeveloped.

Note: A heuristic for knowing who you should not take conditioning advice from: ask them if “lactic acid” exists in the human body.   If they say yes, stop listening.  It does not.  Seek help elsewhere. 

An average resting heart rate between 50 and 60 bpm is the zone I see in people with a well-developed aerobic system, aren’t experiencing abnormal high stressors, and still have robust short term energy systems for adequate strength and power.  I have found most of these people well rounded in their physical abilities.  Thus, it seems to be a good zone for most field and court sport athletes, as well general population with active lifestyles.  If you compete at the either extreme of the conditioning spectrum the heart rate zone will most likely skew that direction.  For example, marathon runners will be in the 50 bpm and lower direction, and a powerlifter will be much higher than 60 bpm, probably even above 70 bpm.

A Safe to Fail Experiment

Jill and I decided to see how her health and performance would respond to training for a lower resting heart rate.  Jill performed a safe to fail experiment to ride the exercise bike twice a week at a steady state keeping her heart rate below 130 bpm.  This zone is relatively low compared to the heart rates seen with max effort sprints.  Initially we started with 30 minutes straight per session, and we built up to 45 minutes.

Jill admittedly found this type of training boring at first.  We considered combining the use of incline treadmill walking or creating an exercise circuit for a similar effect as long as she stayed below 130 bpm the entire duration.  However, she was still pounding on the basketball court for practice most days of the week, and battling some movement limitations so we decided to keep it simple and stick to the bike.  She ended up just using this time to catch up on TV shows or podcasts.

We kept tracking her resting heart rate, and began tracking her average wattage and distance on the bike for each session.  The trends showed her resting heart rate lowering.  Her wattage and distance on the bike went up while staying below 130 bpm each session.  This means she performed more work with same amount of effort, and hopefully with an aerobic system emphasis to fuel it.

Jill’s resting heart rate never dropped below 60 bpm, but it was mostly in the low 60’s over the approximately eight weeks we tracked her data.  More importantly she felt better.  So much so she continued to voluntarily bike throughout the coming months and season (unfortunately we didn’t keep tracking data).  Also, she was back to her usual self on her next attempt at the team’s conditioning test.

What I Would Do Differently

This story occurred a few years back.  Now, I believe our intervention could have been more helpful by having her bike at a lower heart rate of 110 bpm.  This may have created a stronger emphasis to use her aerobic system.   Plus, we could have made more changes to her strength program to help her movement limitations and shift her energy system demands to more aerobic.  Max strength training increases muscle mass and muscle stiffness which creates a greater reliance on the short term energy systems.  This is because oxygen delivery to very muscular areas, or areas with a lot of pressure from muscular tension, is decreased. 

As always, theses physiological changes occur in degrees, not as absolutes, and depend on our physiology type and how much strength we try to gain.  Since Jill was a solid in the weight room for her size and her sport doesn’t require max effort pushing or pressing on an object like an NFL lineman.  She easily had some strength to spare.  Shaving some pounds off the bar or working on different exercises so she can consistently perform the activity she really loves is performance enhancement.

Furthermore, we could have used a movement assessment as another low cost piece of the puzzle to track her progress. Many movement restrictions are a result of the same muscular stiffness used to create strength.  Thus, limited joint motion may give an idea of how biased an individual is toward short term energy system dominance.

A huge challenge is continued performance of high intensity training, like practice or strength training, while lacking requisite movement options.  Movement restrictions amplify muscular tension in an attempt to access unavailable motion.  The restriction of blood flow to the muscles increases, and oxygen utilization decreases.  It potentiates a cycle of greater muscular tension, movement limitations, and decreased oxygen utilization for the activity.

The Bias of Our Training and Genetics

I know, I know… long duration aerobic work makes us a slower sprinter.  Well, if that’s the only training we perform then of course it will!  We have now swung the pendulum too far in the other direction, and changed our physiological bias.  Now, if you compete as a 100 meter sprinter than performing long duration aerobic work in competition season may be a poor strategy.   These type of events are meant to have people biased toward short term energy systems to the extreme.  But a team sport athlete, or fitness enthusiast, are not the extremes on the continuum. 

Moreover, our genetics automatically give us a starting position on the aerobic energy – short term energy continuum.  Some have a gift for either extreme like a high level marathon runner and a high level powerlifter, respectively.  Some have it all to a freakish level like Michael Jordan.  Then there is everything else in between including the pylon shape folk who are not designed to run long distances, or even short distances. 

The Importance of Knowing YOUR Needs

The fitness world is plagued by taking exercise concepts as absolutes, and applying them to every individual and every context.  As beneficial as a particular method of exercise may seem for some, too much or in some cases any of it may be detrimental to the big picture for others.  When the pendulum has swung too far toward a certain physiological bias, it will improve our abilities in one category.  However, it decrease capabilities in other areas possibly needed for performance and the intended goals.  We can better position ourselves for successful outcomes with a greater awareness of our unique traits/gifts, of our potential needs, and of second order consequences from our fitness choices.

 

Graph source:

Franchini, Emerson; Yuri Takato, Monica; August Peduti Dal’Molin Kiss, Maria.  J Exerc Rehabil Vol. 12, No. 6, 535-541, December, 2016
Publication date (electronic) : 2016 December 31
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