Week 11/Once a Runner...maybe again?

 Stayed on the path (in week 11) that I've been pursuing so far in 2024:

Swim: 6,000 yards

Bike: 236 miles

Walk/Run: 27.5 miles

PT (weights/stretching): 3:10

Total training time: 27:37

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The biggest news is the progress I've made as I've begun to pretend I'm a runner again ("Once a Runner"--best running book of all time!).  Specifically, I've begun doing 2 (in practice)-3 (goal) AeT threshold interval workouts/week.  By AeT, I mean Aerobic Threshold or "High Aerobic" workouts.  Typically, in a 5 level intensity structure, this means high Zone 2.

I've put in hours and hours of work in Zone 1--Low Aerobic.  I have a big endurance base now and am very fat adapted at that low intensity level.  I can go all day walking at 16-17 min/mile.  Now I'm trying to transition towards running again and see what my body can do post knee replacement.  I've concurrently built up the strength in my left leg and increased my range of motion in the new knee such that its very comparable to my natural, right knee.

So High Zone 2 means I need to try to keep my HR below 140bpm or so--this is about 80% of my max HR of 175.  So in practice, when I run my intervals, as I see my HR start to reach 140, I slow down.  Over time, I'm hoping to see my pace and the distance I can hold it both increase at this limit.  I'm basically trying to get better at keeping my lactic acid under control as I start to get faster.

I've now completed 4 of these workouts.  The first one was kinda a disaster as I couldn't keep my HR down but I've seen some relatively quick adaptations.  Below is how my 3rd and 4th sessions (these were 4 X (walk 0.5 miles/run 0.5 miles)) went:

The pace is my per mile speed for the 1/2-mile run intervals.  The average HR is for both the walk 1/2-mile and the run 1/2-mile in each interval.  Max is how high my HR got during the run.  I plan to set my Garmin to do 0.5-mile intervals so I can isolate my average HR while I'm running.

Obviously, this data is very encouraging (and also reenforces just how slow my running is right now).  I'm not sure if I really believe the 4th interval (yesterday).  It says I was running 1:30/mile faster at a considerably lower HR.  In reality, I don't think there was that much progress, but clearly I'm running faster at the same or lower HR--just what this training is supposed to cause!  Also, subjectively, I felt better/faster with each of the 4 intervals yesterday and could have definitely added at least one more.  So I'm both getting faster at threshold and beginning to build a little bit more muscular endurance.

Onwards and Upwards!