Run slow or run/walk to stay in heart Rate Zone?

dar89 - 

1st of all how did you get your VO2 max "tested"; were hook up a mask/machine to measure your O2 consumption? If not what was the protocol? (i.e. Maximal stress test done on a treadmill increaseing intensity/incline every 1-2 min and measuring HR?) How did you or whoever did the test define your training levels (aka zones)?

I personally find very hard to believe you were overtraining, maybe you were indeed going a tad to hard/long for your given fitness level hence you might have been overreaching (which I still think would be a stretch) but you certainly weren't overtraining.

Also anything below your VO2 max is an aerobic effort in nature hence even when training at different zones (which are nothing but man made levels to help us train more efficiently) like zone 4 or zone 3 is aerobic training and it improves your endurance at some degree. It is not bad to be wiped after a workout as long as you are ready to train and perform again at the next session.

*I* personally wouldn't slow down to the point you have to walk because that's not really beneficial training unless you are totally an out of shape individual that can't go more than a few minutes running or doing active recovery. In addition, HR training can be misleading if you don't understand its limitations. Base phase is nothing more than doing training at different intensities/durations within your personal limits preparing your body to handle greater loads in the future.

Limiting your training to 'x' zone for a long period of time is a waste of time for most age groupers unless you currently log a significant amount of volume and it requires you to train at lower intensities just to be able to handle a greater volume; but for that we are talking about probably 15-16+ hrs (since most AGers train on avg 7-8 hrs).

Assuming your VO2 max was tested or guesstimate correctly and your training levels calculated following a good physiological reasoning, I *personally* would go at an easy conversational pace (RPE 1-2) that feel almost too easy if I am shooting for zone 1 and let the HR be whatever it is but wouldn’t slow down so much I have to walk. 

There is a linear correlation between oxygen consumption/HR and speed hence I rather train athletes by pace but short of having training paces then IMO you could guide your effort by RPE while you understand how your HR reacts at different intensities based on your current metabolic fitness. You can do this for 4 weeks and sometimes HR might be higher or lower but most of your runs will be around the same RPE/pace and the HR avg for all should give you a better idea what your zone 1 or 2 really is.

Ok so it seems the test was more than a guesstimate which is good though without knowing the equipment it might be off or not but that is another topic and it doesn't matter all that much to be honest. Did they happen to record what was your speed/incline when you achieved the oxygen consumption plateau (VO2 max or peak)?

If so you could use that to determine your training paces using Daniel's VDOT or McMillan online calculators and most likely that will be more in line with the work done by your muscles (legs) when exercising and will be a better measure of your training intensity as opposed to your heart rate. As I said HR can be misleading unless you understand its limitations but if you get to know how your different training levels relate to it can be an effective tool.

Please know that I am not trying to discourage you to use a HR or the training levels, what I am suggesting is for you to also take into consideration your perceived exertion, possible guide your efforts by it and/or pace and learn how your HR relates to that. While the relationship between oxygen consumption/HR vs. speed is mostly linear other things can affect your HR hence it might make it tricky to gauge the real work done by your legs at a given moment.

Finally, by limiting your training to a particular heart rate zone that might be indicative of the work done on your legs or not, and even walking in order to remain within that target zone IMO you will be wasting some precious time you could use to achieve greater fitness gains by just running by feel.

Go at a mostly easy pace, ask your self if this feels easy (RPE), if you know your training paces-check your speed, and check the HR to see what’s it is saying. In the course of weeks after you learn to relate each other you’ll know when your HR is misleading you and you can just go by pace.

PS. for biking a HR can be a great training tool (short of a power meter) because unlike running when speed can tells a bit easier how hard or not we are working, on the bike we have other variables to consider hence the use of a HR can be rather effective.

Good luck!