Can I break 20:00 for a 5k part two Masters??

Where do you find the 5k prediction on Garmin?

Scroll down through screens using left-bottom-button. The screen that displays ‘VO2 Max’ also displays the current ‘5k Estimate’.

It says my current VO2Max is 56.

When on that screen, pushing upper-right-button takes one further into ‘scroll-down’ readings; one of those sub-screens displays Lactate Threshold, another displays ‘Race Predictor’ (for 5k, 10k, Half and Marathon).

I have a Garmin 935 (or is it 945?), coupled to a (2 or 3-yr-old) Garmin TRI chest strap.

I have a Forerunner 45

don't have that feature

You will get a much more accurate 5k estimate by running an all-out 3k, 3200m or 12-min time trial, then plugging the results into Jack Daniels’ Calculator, which will provide race equivalents. Even a mile time trial will be okay.

Day 8, June 26, ‘23
PM: 20mile somewhat-hilly country-side bike ride.

Day 9, June 27, ‘23

AM workout:

‘Run-fast-drill’ (7 x ’100-up-striders’ w/full-recovery to ~90bpm.)

Rep
Time…Pace…AvgHR/MaxHR….SPM/Lngth..GCT
27.8……6:22/mi….105/120bpm…208/1.04m…169ms
28.1……5:33/mi….108/124bpm…216/1.23m…146ms
27.1……5:04/mi….130/148bpm….218/1.39m…140ms
27.9……5:12/mi….115/146bpm….216/1.33m….140ms
28.0……5:36/mi….113/142bpm….209/1.28m….160ms
30.0……5:17/mi….123/149bpm….208/1.43m….146ms
28.4…..5:14/mi…..123/146bpm….214/1.33m…..150ms

Notes: Would have to check, but these may be similar to ‘Billet 30s’.
Shoe: Speed6

Post-workout Garmin 5k estimate: 19:15

That was a tuff workout, due to lack-of-oxygen for 30 seconds immediately following rep.

These are a variation of Walter George’s ‘100-up Exercise’, but done moving forward on a track, rather than stationary-in-place.

From a rolling start, click the lap button, count every time left (or right) foot contacts the ground, and hit the lap button when you reach 50 (i.e., 100 strides total).

Day 9, June 27, ‘23
PM: ‘Threshold Bounce’ (30 cycles bouncing between HR triggers of 80%-HRmax & 88%-HRmax).

Notes: There is much I could and might say in the future about this incredible running workout that I personally devised. For now, a forum search might reveal more info on it from posts of mine a couple of years ago.

I’m not in the physical condition I was two years ago, and ended up walking, rather than jogging, home afterwards. Suffice to say, for now, I’m currently experiencing some insomnia from entering over-training territory. Will probably just do recovery walk(s) today.

The workout is more appropriately called ‘Sub-Threshold Bounce’. Here are two examples of this workout I posted on 6/4/21. I performed this workout twice that same day.

6/4/21 AM:

ibb.co

6-4-21-AM-Sub-Threshold-Bounce

Image 6-4-21-AM-Sub-Threshold-Bounce hosted in ImgBB

Link:ibb.co/s2s80sd

I perform this workout on a ~0.2 mile long, rather steep, hill. I run up the hill until the 88%-HRMax trigger is hit, then jog-shuffle down the hill until the 80%-HRMax trigger is hit, and then repeat that process for X number of cycles.

I'm nowhere near a 20:00 5k at age 39 and this is a good thread. (Right now I'm struggling getting into the low 22s (22:13 estimated 5k right now) but have 800 miles of base on my legs so far for marathon training). Thanks to all who gave input in this thread and the other one!

You may get some training ideas here. That workout I most recently posted might be a very very good, key workout. That ‘100-up Striders’ workout posted before it is something I just came up with recently, and might be a very good one, too.

I haven’t yet taken the time to closely review my training history back when I was at 20min fitness a couple of years ago. But I came across a couple of interesting threads for info.

I posted under the handle ‘Jack Daniels Calculator’ back then (before someone else registered that name.)

Day 10, June 28, ‘23
Off.

Day 11, June 29, ‘23
AM: 15xHill-repeats.
Run to top of hill until HR-High-Alert (set to 147bpm, i.e. 86% HRmax) goes off. (Due to time-latency in watch-trigger, 87% HRmax is typically achieved before the High-Alert goes off.)
Jog-shuffle down the hill and repeat.
HR typically recovers to 71% HRmax before starting back up hill.

Day 11, June 29, ‘23
PM: 15xHill-repeats (same as AM.)

Notes: Total distance covered in 15xHill-repeats (both up and down hill) is ~5k.

That does not include any warm-up or cool-down.

Day 12, June 30, ‘23
PM: 5x1k, 3min rest

Rep
Time….Pace…....AvgHR/MaxHR...SPM/Lngth..GCT
4:13……6:40/mi….156/160bpm….181/1.32m…218ms
4:18……6:49/mi….158/165bpm….182/1.29m…223ms
4:18……6:48/mi….158/165bpm….184/1.28m…227ms
4:22……6:54/mi….158/164bpm….183/1.26m…227ms
4:24……6:58/mi….158/167bpm….184/1.26m….222ms

Notes: This was a tuff workout; the reps were difficult, pretty much all-out. Hill-reps from previous two days (60 total) were in the legs.

Ran at sunset, lightning to the East.
Temp: ~80degF.
Dew point: 72degF.

Post-workout Garmin 5k estimate: 19:09.

Note: that session was done in a 3yr-old pair beat up Vaporflies.

Day 13, July 1, ‘23: Recovery, walked two sessions, 9 miles total.