To Your Well-Being: The Speed Limits of Exercise: First, take the foot off the brake.

Contributor: Rich Butler, MS, USPTA
To learn more about Rich, click here.


image007.pngMy daughter peeks over my shoulder and takes a glance at the speedometer to ask “Daddy, what is the speed limit? Are we going too fast?”  She understands that in school zones we drive slower, on the highway we drive faster, but she can’t remember our trip to Texas where we traveled around 85 mph, legally.  But with time she will gain the experience necessary to make her own judgments.  So it goes with exercise.  Weekly I am asked “I don’t want to get my heart rate too high, do I?”  Let’s look at it.

The relatively new trend toward H.I.T. ‘high intensity training’ or ‘interval’ focused exercise plans has added a dimension to the traditional exercise model.  Interval training, defined as nearly maximal effort for up to a few minutes or so, but done repeatedly following an appropriate recovery phase, has been studied much more over the past decades.  If you have ever attempted a ‘Tabata’ workout but were not sure of the origin, here it is.  Dr. Tabata was the lead author of a study that asked 7 subjects to bike for 20 seconds at an effort that was 170% of their VO2 max (highest oxygen utilization in 1 minute).  VERY painful!  They were then given 10 seconds of rest.  This protocol went on for only 8 minutes.  5 days per week.  Although short in duration, it is a brutal effort.  The findings were that the VO2 max and the anaerobic threshold of the subjects improved more compared to ‘steady-endurance’ training for 60 minutes.  So why not scrap all this slow and steady stuff and crank up the effort in 20 minutes and get out of the gym?  There are plenty of people who are challenged by time commitments, so this sounds good to them.

Well, if you take a look at the paradigm in The Running Formula, author Jack Daniels, PhD clearly distinguishes between the different zones that can be used with training runners.  And although you might not think of yourself as a runner, you are.  You have the lungs, the heart, the blood volume, the mitochondria and arterial system to make it happen.  And if you have an anatomical limitation then you can ‘run’ in some other form like cycling, arm ergometry (measuring of the amount of physical work done by the body, usually during exertion), swimming, or hill walking.  So let’s stick with the model that you are trying to improve your running.   

A simple 3 zone model will be used for our purposes to describe the training options: 

I. ‘Base/Endurance’ training at a ~60% effort

II. ‘Threshold’ training at ~75% effort

III. ‘Max’ or ‘High Intensity’ training at > 90% effort

Zone 1 was and still is the ‘Base’ effort that humans (and plenty of other mammals) use when they need to cover distance.  They feel little fatigue, fat is the primary fuel source, and the ability to deliver oxygen for long periods of time is not that challenging.  This is your ‘migrating’ zone for those of you headed south this winter.

Zone 2 might better reflect the effort you give when you get a notification on your phone that the rain is coming in 10 minutes and you must get back home.  It won’t be easy, but you can make it.

Zone 3 is sprinting. It is clearly a fight-or-flight effort that uses instant energy sources that run out very quickly and lead to fatigue and muscle failure.  The stress level is high, but it is over quickly.  This effort tests the cardiovscular system near the max, but that may be why some of the muscular adaptations are profound.

Dr. Daniels often uses the phrase “Prove it” when one of his runners attempts to modify the running schedule with more of Zone 3 or less of Zone 2.  But when you look at the examples of how to schedule a running program, there is no mistaking his philosophy, lots of Zone 1 while sprinkling in some Zone 2/ 3 or “High Quality” training appropriately.  Why?  Zone 2 and Zone 3 are hard, and the stress of applying them, for a lifetime, can seem daunting.  Many individuals use the world of sports, like tennis, basketball, boxing, soccer, or classes led by a trainer to get their H.I.T. in, but when on their own, working at near maximal levels can be difficult.  Goal setting becomes very important at times when trying to stick with these plans.  Like beating your sibling in the local 5K.

Exercise benefits hinge on the ability of someone to comply with the exercise dose. In the business of prescribing exercise, individuals have many hurdles they need to get over, and it doesn’t take long for a clear view to emerge on why they didn’t complete the task: it was too hard (Zone 3), too long (Zone 1), too boring (Zone 1), or too complicated (Zone 2).

Your best ‘speed’ is going to be the effort with which you can comply.  Some of us are sprinters, some of us are migrators, some need to be outside, and others inside. Maybe you are checking the stock market or reading a novel, but, regardless of how you achieve your exercise, you must take your foot off the brake and get up to speed.  In time, add 1 beat per minute to your HR range, tack on 20 minutes to your long workout, but in the end remember ‘Something is better than nothing, but compliance is everything.’


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  1. Foster C. “The Effects of High Intensity Interval Training vs. Steady-State Training on Aerobic and Anaerobic Capacity.” Journal of Sports Science and Medicine, Vol. 14, No. 4, Dec. 2015, pp. 747–755.
  2. Daniels, Jack. Daniels’ Running Formula. Human Kinetics, 2014.
  3. Tabata IN, Kouzaki K, Hirai M, Ogita Y, Miyachi F, and Yamamoto K. “Effects of Moderate Intensity Endurance and High Intensity Intermittent Training on Anaerobic Capacity and VO2max.” Medicine and Science in Sports and Exercise, Vol. 28, No. 10, ser. 1327-30, 1996. 1327-30.