High Intensity Interval Training

Are you sick of exercising?  I am.  At least, exercising for exercise's sake....

One of the reasons I was drawn to The 4-Hour Body was its claim that exercise is OPTIONAL.  Additionally, it also introduced me to the concept of high-intensity interval training (HIIT).

HIIT turns conventional wisdom on its head with regard to the necessity of prolonged exercise for weight loss.  The concept is simple.  Intersperse short bursts of maximal effort with intervals of rest.  I decided to look into the physiology and biology behind this phenomenon.  I wasn't disappointed as there is a lot of quality research on this topic.

Quick review.  Skeletal muscles import glucose from the bloodstream to convert to energy.  Glucose enters the skeletal muscle cell through several receptors, including the GLUT4 receptor.  The production and movement of GLUT4 to the outer cell membrane is stimulated by insulin.  As it turns out, intense muscular contraction effects the same upregulation, independent of insulin.  When more GLUT4 is present on the outer membrane of skeletal muscle cells, more glucose can be transported into those cells.  This transport mechanism, along with insulin-stimulated GLUT4 up-regulation, helps maintain glucose homeostasis, preventing excessive highs and lows of blood sugar.

A key component of The 4-Hour Body body recomposition is dietary control of blood glucose elevations, and therefore the release of insulin.  Contraction-induced up-regulation of GLUT4 is a way to attenuate the insulinemic effect of such a load - more GLUT4 receptors enable more insulin-independent glucose uptake into muscle cells, thereby decreasing the insulin that would otherwise be required to accommodate the increased blood sugar.  Why is this good?  In basic terms, insulin in the bloodstream, especially excess insulin, can facilitate fat storage.  We can these exploit these facets of physiology when attempting to lose weight.

HIIT need not be an arduous process.  Basically, you alternate between low intensity activity (i.e. walking) and brief bursts of maximal-effort activity (i.e. sprints).  I have added HIIT two times per week - I walk about 10 minutes to a big hill in my neighborhood, then sprint up the hill 2-3 times (and walk down each time).  It takes about 30 minutes roundtrip, with 20 minutes of that being the walk to and from my house!

The possibilities are endless - walk a lap around a track then run the bleacher stairs, hang out in the pool and intermittently sprint for a lap or two, or take a leisurely bike ride with an occasional uphill power pedal.

I know this is a big paradigm shift for a lot of people.  It is for me.  After all, we all have been inundated with the conventional wisdom that weight loss requires a dedication to time- and energy-consuming exercise.  Not only may this phenomenon enable physical activity for those who need it most, but it may prove beneficial in type 2 diabetics who often suffer from hyperglycemia due to decreased insulin-sensitivity.

Looking forward to seeing what happens!