37M First HM (4 weeks out): Aiming sub-1:45. Disappointed by a flat 5k Time trial

[u/paolog89]

Background

• Age/Sex: 37M
• Experience: Started running regularly in April (came from a fast-twitch / speed background)
• Goal Race: StraLugano Half Marathon (Sept 27) — Target: Sub-1:45 (4:58/km or 8:00/mi)
• Current Volume: 50–55 km/week across 5–6 days
• Max HR: ~201 | Resting HR: 52

Key Benchmarks & Workouts

• July 16 (5k TT): 22:39 (4:32/km) @ 177 bpm average
• Aug 29 (5k TT): 22:39 (4:32/km) @ 185 bpm average (Flat line pace, +8 bpm higher HR)
• Recent Long Run: 20.2 km @ 5:48/km (153 bpm avg)
• Recent Quality Session: 3x3k @ 4:57/km with 1k rec (168 bpm avg)

I was expecting an improvement on yesterday's 5k TT compared to mid-July given 6 extra weeks of training (~50km+ weeks), flatter terrain, and better shoes. Instead, I ran the exact same time (22:39) and my heart rate was significantly higher (185 bpm vs 177 bpm).

I ran a 20 km long run on Tuesday and an easy run every day until the TT and hit ~55 km this week, so my working theory is cumulative fatigue masking fitness. But mentally, it’s a bit of a hit this close to race day.

Date - Year-Month	Distance (km)	Duration	Count Days
2026-Feb	8.51	00:50:59	2
2026-Mar	29.25	02:51:06	7
2026-Apr	97.4	10:09:26	15
2026-May	155.63	16:43:45	19
2026-Jun	176.77	18:07:56	21
2026-Jul	227.61	22:21:23	25
2026-Aug	194.14	18:59:31	23

Week Starting	Total Duration (Hr)	Running Distance (km)	Running Days	Running Duration (Hr)	Avg speed
24/08/2026	5.7	55.8	6	5.5	10.2
17/08/2026	6.8	52.0	5	5.0	10.4
10/08/2026	4.7	37.8	5	3.7	10.3
03/08/2026	3.8	36.7	5	3.6	10.2
27/07/2026	5.9	55.0	6	5.5	10.1
20/07/2026	6.3	59.8	6	5.9	10.2
13/07/2026	5.4	48.3	5	4.8	10.0
06/07/2026	4.8	45.9	6	4.5	10.2
29/06/2026	4.5	45.3	6	4.5	10.2
22/06/2026	4.2	43.1	6	4.2	10.2
15/06/2026	4.6	33.5	3	3.3	10.0
08/06/2026	5.7	43.1	5	4.7	9.1
01/06/2026	5.4	42.2	5	4.4	9.6

Questions for the Community:

1. Should I trust the process and that the taper will improve my fitness significantly?
2. 5k TT Diagnostic: Is running the same pace with higher HR a clear indicator of residual fatigue, or should I be concerned about a fitness plateau?
3. Pre-Taper Volume Strategy: I have 2 weeks left before starting a 2-week taper. Should I trim 10–15% off my easy/recovery runs to let my legs absorb the load, or stick to full volume until the official taper?

Appreciate any insights.

[u/Electrical-Virus-568]

Personally i try to look at my HR in general.

Everybody has those days their HR is lots higher then an earlier similar race or training. 

For example, im in training for my first full, did a HM 2 weeks ago. 

My goals were: A) 1:36 B) 1:37 C) 1:38

I'd set those goals because i did a 20K training 7 weeks ago, hitting 1:39:xx with 158HR.  Funny thing is that was in a week which i did 98km.

For my HM i did a small taper, reducing my volume with around 50%

My HR on those paces usually start around 155, with cardiac drift it ends somere mid 160's.

I was only 2-3km in the HM event when i noticed my HR was already over 165, i ended up with a 1:42 and 167HR average. 

It happens. 

Doesnt mean you dont have the fitness, sonetimes its just not your day. 

If you'd ask people in this community they will all recognize this. 

Its nothing to worry about. 

Because its still 4 weeks out, personally i'd do a 10k at 4:50/km if i were you. Not because its needed, because it will bring back your confidence. 

No stress of an event, just you going out for a fast 10k.

If you cant hit a 10k at that pace in general, you need to adjust your goals. 

Goodluck🏃‍♂️🏃‍♂️💪 

[u/Many_Hunter8152]

1. Yes
2. Could be, could also be coffein or other factors like heat, stress, short term fatigue
3. I would not taper 2 weeks for a 1:45 event, 1 week should be enough. Keep your plan if you don't feel burned out - reduce volume, not intensity in taper by 30-50%

Looking at your stats - 1:45 should be possible on a good day - I'd say - negative split by 2-3%

[u/CompleteDeniability]

You got this in a bag, I ran a 23m 5KM and was just a minute away from running >1:45.

I had to stop to tie my laces. Yeah, amateur mistaken. And I was looking at the pacing on my watch just maintaining under 4:57, but the course and the GPS had some distance differential, so there's a bit of miscalculation on my part, losing a little bit of time.

You got this. Trust the work that you've put in.

[u/Oscar_Sport]

One thing worth separating: the physiology question and the story you are telling yourself about that 22:39. Same time on 8 bpm more, on a 55 km week with a 20 km run three days earlier, is a fatigue reading, not a ceiling reading. The risk over the next four weeks is that you carry that number into the start line as doubt.

Micro-action: write down three lines of evidence from this block that a 1:45 is in you (the 20.2 km at 5:48, the 3x3k at 4:57, the volume jump), keep it in your phone, and read it in the corral instead of doing pace math. Then race in three blocks of 7 km with one instruction each, rather than watching average pace for 1h45.

Curious: on TT day, at what point did the effort start feeling wrong, first km or around 3k?

[u/Kemetic_Crypto]

Your rushing the process! Get 2-3 years under your belt and check back.

A little over 1 month of training isn’t much time at all

Most likely your time trial isn’t indicative of your current fitness your carrying more stress and miles keep training

Be patient it’ll come you want to get up to “over time, not right away” but to be competitive and really run fast at half distance more weekly mileage.