I don't feel the same this year. I have been steady with good efforts on the spin bike and lot's of physical work but my legs feel like they are starving. After a ride I am more tired than usual. I use a heart rate monitor and even modest efforts seem to drain me quickly. I raced a lot of BMX all through the years and have maxed my heart out thousands of times but I don't feel comfortable doing that any more. My legs still bulk up so they are feeling the effort.
Say for example, I am rolling along (20 mins in) on the spin bike at a cadence of 80 and a HR of 145 seated. I really feel like I should be able to stand with same resistance drop the cadence to 40 or so and it should take around one min. to get up to 160 BPM. It's now only 15 seconds or so. I am 53
I took my blood pressure a few times this week when I was already tired at the end of the day. 112/60 average. I guess my blood feels too thick for lack of a better description though I am sure that is not the case.
My wife asked me if I would do a stress test when I brought this up. I said "yes, and Ill crush it".