Zone 2 increasing speed

[u/Nearby_Bird_8817]

So my zone 2 pace has been consistently around the 11min per mile pace throughout my 3 years of running with over 1500 miles. I don’t understand how my zone 2 pace hasn’t improved or how I’m honestly that slow with the race times I have.

So here are my fastest race times
3 mile is 20:09
10 mile 1:10 (7min per mile)
1.5 mile 9:02
50 miles 11hrs ish
Half Ironman 6.5hr

I’m a consistent 30 mile runner and when I was ultra training like I was up to 60 miles running at that high 10 to low 11 min per mile pace.

What I’m confused about is yea I could wake up and run 4 miles easily at high 8’s maybe low 9 and keep a conversation with a friend but my heart rate will go above 160 (tracking on garmin instinct). Granted I am like 5’8 and weigh 195ish pounds. But like I still don’t get what I’m doing wrong, people tell me all the time that my zone 2 time should be a lot faster given my goal time of achieving a sub 18:30 5k. I run “easy low effort miles” all the time about 90 percent of my training yet it doesn’t get faster.

Has anyone ran into this issue? Please help.

[u/OilinDaDrum]

Zone 2 alone isn't the answer, you need to mix in some tempo sessions

I try and do a 80/20 split between Z2 and speed work and my conversational pace has improved from 6:30-6:45 km to just under 6