Share something that i have found :
Actually, my anecdotal feeling is that, the change from night sessions to morning sessions so as to avoid the sessions from interfering my sleep and hence able to get more sleep + better quality sleep (daily can get 1hr of additional deep slow wave sleep) as per my smartwatch sleep tracking, and the added focus on strength sessions (actually this one more for cycling) which leads to better and more productive workouts / sessions got effect.
I think maybe higher strength also leads to better muscular/oxygen usage efficiency, however slight that might be. I noticed this esp for my Sentosa Imbiah climbs, coz i like to mini TT it plus check HR at X kmh speed, eg 8kmh 60 rpm can now keep it below 120bpm....this sort of "check" i can literally keep seeing the progress in 2 weeks time frame and sometimes from week-to-week also can sense slight improvement.
Coz increases in weight/reps for a particular strength exercise might not correlate to better timings/HR etc.
Another point is, i noticed I havent been failing any of my workouts also.
Also, the HR at such paces is somewhat lower than when i just purely doing run training 2-3 yrs ago. (gotten similar times at my best run fitness then).
And all these together with significantly higher muscular mass and much higher strength, which generally is a good thing for older folks.
Last time i was "stick thin" at 56-57kg even though I could run, now is 73-74kg (of coz i think at least 3-4kg is water weight due to Creatine supp).
Last time 2-3 yrs ago also barely could do any dips/pull ups (ummm.....like 1 rep?) and heck even just a dozen push ups also literally RIP before i started trying with push ups and then pull ups/dips, bloody weak last time.