It was purely coincidental that my first run of the year was to be (according to my JD plan) a "long run". I had been doing run/walk long runs over the past few weeks - basically running while watching my HRM and trying to maintaining a low HR.
But, I "discovered" on my phone a 2 hour long Audiofuel MP3 that I had forgotten about - and on a whim, decided that I would try it out. It has music on it which goes from 160BPM to 170 BPM - a bit slow for comfort for me really - I prefer a cadence just a little it faster - but anyway, I went with it. It was meant to be a 'slow" long run - so I took it easy and finished the 10K non-stop in 90 minutes - my long run pace according to JD is supposed to be 08:42 - 09:10, so it was about right. My HR stayed quite low for the first 5k - but started to rise in the return 5K as It was quite warm and humid and I was sweating profusely even at this slow pace. Sweating means more blood being pumped to the skin to cool down - means higher HR. Lungs and leg wise , it was quite easy , but a little tiring, for me.
I have signed up for a 10 K "race" at the end of March -- I did run a 14k race last year at 7:30 min per K - this was done run/walk - I am not sure that I could repeat that pace over 10K running non-stop , but time will tell over the next couple of months. Anyway, at age 68, I am happy with where I am at!!