HIIT or Easy Run?

Decisions, decisions.  I am in the process of writing a 10-week training plan for my next half-marathon in June, the Rock n Roll San Diego Half. With a 1:40:34 finish at the San Diego Half Marathon a week ago, I set the bar high for attempting to achieve another PR. Uncertain of how much further I can improve my ability for a faster pace, I’m trying to decide on the type of training I want to do.  Should I continue with an increase in mileage with Easy Runs or try a completely different approach, High Intensity Interval training or HIIT, a workout that’s been studied as also being effective in developing your endurance capacity.


I recently listened to a podcast by Ben Greenfield titled “The Two Best Ways To Build Endurance As Fast As Possible (Without Destroying Your Body) – Part 2”   It’s actually the audible version from a chapter of his book Beyond Training which goes into excruciating detail as to why High Intensity Interval Training (HIIT) is a viable option to replace long slow aerobic training and still reap the same benefits.  I also found another article from IDEA Fit, HIIT vs Continuous Endurance Training: The Battle of the Aerobic Titans regarding the same topic basically discussing the science behind how the body’s response to HIIT in terms of cardiovascular, skeletal-muscle and metabolic adaptations is similar to continuous endurance exercise.  So I thought why not replace an easy run during the week with a HIIT cross-training workout such as indoor cycling.  Another research presented in a Runner’s World article, 15 Minutes on a Stationary Bike could make you a Faster Runner revealed that “HIIT sessions, combined with the shortest periods of rest, increased running speed the most.”

The training plan I followed for the San Diego Half consisted of 4 days of running (M, T, TH, Sat) with 2 days of cross-train (row/strength train), however in February with the strength streak, strength training was a daily regimen except for a few days missed.  My peak mileage was a mere 38 miles, but it was enough to improve my fitness level since week 1 of training.  With the HIIT option, my training would look like this (peak mileage around 33miles):

M:  HIIT cycling + additional weight-training

T : Track workouts with SDTC (focus will be on Yasso 800s)

W: Hip strength/mobility and Core

R:  Easy mid-long run (first 4 weeks), Include threshold runs (final 4 weeks prior to taper)

F:  Cross-train

S:  Long run


Is this an appropriate training plan to run a sub-1:40?  I know it goes against the grain of specificity of training and developing the aerobic system.  However, if the studies hold true with regards to HIIT being as effective, then this training plan should work.  It will be an experiment and the findings to be revealed on race day 5th of June.

Tell me your thoughts – Easy Run or HIIT?