Something quite unusual is happening to me ( I think) . I restarted wearing a heart rate monitor about a month ago and basically wear it on every run now. I set it to show "average" HR -- I actually have two HRM's and their average displays are different - one works by starting the stop watch in the watch - and it then averages out HR until the stopwatch is stopped, hence it shows the average HR for the entire run. My other one only averages HR over the past couple of minutes - hence it shows the current "average" HR as you run. This second one is the one I have been using.
Early days of experimentation showed me that my max HR when walking as fast as I can was about 95 -- but as soon as I started to run , however slowly , it immediately leaped up to 120+ . As my absolute MAX HR is around 160, this did not leave much headroom between running very slowly and running flat out.
I have been using one of Jack Daniel's "training for fitness" programmes - one day per week is 30 min easy with 6 "strides" at the end of the run ( at a very slow pace, 1-1:30 mins per K slower than current 5K race pace) , 2 days of tempo runs - about 40 minutes at around 10 seconds per K slower than 5K race pace and a long run at easy pace ( which I use run/walk to do as I have decided that anything over 5K is run/walk for me)
I also gave up drinking coffee about 3 weeks ago.
The unusual thing that is happening to me ( and it has happened for the second time today ) is that I can now run at the very slow easy pace without feeling the pain in my calf muscles that slow running previously induced AND at a low HR below 120 BPM (unheard of for me!!) I can only think that this Jack Daniel's plan is indeed improving my fitness, or it's a culmination happening after a year's running -- OR it's the reduction in caffeine intake.
In any case, I am happy with the development!