I strained my calf while getting ready for the 5-month program (too much too soon), which I will finally be starting for the 2nd time on Tuesday the 22nd (doing the 20-min HR test tomorrow). 

Due to the calf injury (and previous back injury) I didn't exercise for 5-6 months and prepared only 1 week prior to the speed test. Thus, I'm a bit overweight (about 7 pounds) and out of shape. I ran the mile in 7:30, but I'm sure under normal circumstances I could have done the mile in less than 7 mins (I've done it in under 6:00 in the past). 

Does anyone know whether it's ok to change the HR and SP zones after some training? I would really like to train at the top of my capacity. On Phase 1, week 4, day 4 and 7 are days off - maybe re-doing the tests on those dates when I'm in better shape could also set the standards to continue the remaining time? 

Eric does state running for longer periods in the self-guidance tips based on how your body reacts to the training, but doesn't mention anything about re-doing tests while in training or switching HR and SP zones throughout the 5-month program. 

Thanks everyone for any advice/help. 


Views: 254

Reply to This

Replies to This Discussion

You retake the tests partway through the program, if you're referring to the cool impossible program. Have you thought about doing the preparation phase (4 30-minute easy runs a week, for 3-6 weeks)? It sounds like maybe you could use it if you haven't been able to run recently. Then you can redo the tests before you start the 20 week program.

Hi, I had similar concerns to you and had a number of set backs due to injuries. 

Although I agree it would be best to optimize training with dialed in HR and SP zones I think the best benefits will come through consistency and completing the program. 

I found that there was enough variation in performance based on how i slept (having a young daughter), what I ate and dealing with work stress that focusing on completing the program, being consistent and avoiding injury are more beneficial goals than optimizing the training.

Also the tables presented by Eric are still approximations (although I think probably very good ones) so making sure you are running and consistent are very important. Being patient is key. 

Hope that makes sense.

Thanks a lot for the thoughtful reading and the reply, Ben.

I have run most of my life to keep myself in shape and competitive to do other sports. After 33 or so, I have suffered injuries every 2 months while doing sports (soccer and tennis mainly), which is the reason I gave up on them.

Finding TCI gave me the the final push to focus on running, and hopefully, allow me to be competitive while staying injury free. So, I definitely understand when you say that avoiding injuries is more beneficial than optimizing training.


Great advise everyone, thanks for your insight in helping Andres.

Andres, I would continue to retest for new training zones every 8 weeks or after each phase.  And Ben's advise on consistency is really key.

The Three P's:

Consistency + Patience = Performance

Dear Eric, it's the second time you take the time to answer my questions, thanks so much for taking the time to clarify everyone's doubts on the forum. Again, your book and born to run have been tremendously inspiring. I really hope I can complete the 5-month program. 


You are welcome and I really appreciate your thank you!  Take it one day at a time and you can complete it!


Train With Eric

Foot Core

The Cool Impossible by Eric Orton

The Cool Impossible: Run Beyond Limits

“this is by far one of the best training books of the past decade.” - Competitor Magazine

Order link:





  • Add Photos
  • View All




© 2022   Created by Eric Orton.   Powered by

Badges  |  Report an Issue  |  Terms of Service