To Cardio or Not to Cardio…

Cardiovascular exercise is extremely important.  Like I said before, you are definitely more likely to die of something heart related than you are strength or flexibility related.  CHD is killing 1/4 of us and that is a problem. (1)

Cardio falls into two categories usually by doing long and slow at medium intensity or short and fast at high intensity.  Either can be done in any fashion, bikes, running, etc.  But what’s the difference and what should you be doing?

Your body’s arteries are like highways.  They can be wide, 6 lane ones and easily accommodate more cars at a time to travel. Or, they can resemble more narrow 2 lane highways where the cars would have have to drive faster to transport the same number of vehicles the same distance.

The highways expand because the volume of traffic increases.  When there is little traffic, the highways don’t need to expand too much so lets say they can put their money into higher quality roads so the cars can drive faster.

This is eccentric and concentric hypertrophy of the heart.
Although this would suck to drive in having valves that can pump large amounts of blood per stroke can send oxygenated blood much more efficiently.

The heart’s left ventricular cavity can get stretched out and pass more blood per stroke (stroke volume via eccentric hypertrophy/dilation) or it can thicken and strengthen its walls and push blood out faster and harder (concentric hypertrophy).

Eccentric is associated with the long, slow and medium cardio.  Concentric is associated more with the short, fast and intense versions like sprints and exercise that isn’t as cardiovascular like pure strength training.  Many studies show that both  forms of cardio are great for improving health markers such as fat loss, reducing blood pressure, and increasing VO2 Max. (2, 3, 4)

There’s a catch.  The short, fast, intense stuff…is…intense.  And if you are truly doing it intensely, it is too hard on the system to repeat often in the week. High intensity forms usually require greater physical prerequisites to do safely as well.  If that is your only form of cardio, you’re more likely to burn out.  Burning out is a drop in consistency and perhaps a inhibitor of results. 

Also, if the intense stuff is all you do or it’s more like you do no cardio at all because it “eats away your muscle” your main muscle, the heart, will slowly suffer.  That heart receives a majority of concentric hypertrophy stimuli which stiffens and thickens the heart.  This is great for “powerful” hearts, but not hearts that need to have some flexibility to handle internal pressure long term.  You might even argue that pathological hypertrophy found in heart failure shares some characteristics with a purely strength trained heart with its stiff and thickened nature…

So…we all need some medium intensity work to help change our heart in ways to make life easier on it and to reduce the overhead physical stress that is coming into our bodies long term.  This allows you to train at high intensities more often and more efficiently because your body is not overworked. And you definitely can’t skip cardio because that’s like just handing yourself over to CHD. 

Give yourself some love for the long-term and do some balanced heart things often 🙂

Written by: Collin McGee, Dr. Borgatta MD


  1. CDC, NCHS. Underlying Cause of Death 1999-2013 on CDC WONDER Online Database, released 2015. Data are from the Multiple Cause of Death Files, 1999-2013, as compiled from data provided by the 57 vital statistics jurisdictions through the Vital Statistics Cooperative Program. Accessed Feb. 3, 2015.
  2. Ramos, J.S., Dalleck, L.C., Tjonna, A.E. et al. Sports Med (2015) 45: 679.
  3. Maillard, F., Pereira, B. & Boisseau, N. Sports Med (2018) 48: 269.
  4. Scribbans, Trisha D et al. “The Effect of Training Intensity on VO2max in Young Healthy Adults: A Meta-Regression and Meta-Analysis.” International journal of exercise science vol. 9,2 230-247. 1 Apr. 2016

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