---
date: 2026-09-04
type: run
tags: [run, evening, week1, heat]
---

# Run — 2026-09-04

**5.04 km in 36:31 — 7'15" pace at 159 bpm. Evening slot (19:29) in residual heat after a 5h45 night. Felt slow, breath tight, HR high for the pace — data confirms all three (25 min in anaerobic). Went anyway, finished, and is glad — the discipline win on a day the body wasn't offering much. Second run of week 1 (Wed/Fri/Sun clock).**

## Data

| Metric | Value |
|--------|-------|
| Distance | 5.04 km |
| Duration | 36:31 |
| Avg pace | 7'15" /km |
| Fastest pace | 4'54" /km (burst) |
| Avg HR | 159 bpm |
| Max HR | 176 bpm |
| Cadence | 156 spm (max 175) |

| Metric | Value |
|--------|-------|
| HR recovery (2min) | 20 bpm (dropped 20, 175→134) |
| VO₂Max | 46 ml/kg/min (maintained, "average") |
| Steps | 5,724 |

**Splits:** KM 1 — 6'44" · KM 2 — 7'10" · KM 3 — 7'55" · KM 4 — 7'17" · KM 5 — 7'07" · last 0.04 km — 0'18". The fade is in the middle: km 3 at 7'55" is the heat+debt wall, then a controlled re-settle.

**HR zones:** Extreme 0 min · Anaerobic **25 min** · Aerobic 8 min · Fat-burning 2 min · Warm-up <1 min — the run sat above the easy ceiling for most of its length (avg 159 ≈ zone 4 with HRmax ~190). This was NOT an easy run in disguise.

## Sleep — Night before

**5h 45min** · 02:11→07:57 · REM: 15% · Deep: 30% · HRV: **111** · Resting HR: 52 · Score: 80/100

> Home ~midnight sober, couldn't fall asleep until 02:11, slept in to 07:57. See [[Sleep/2026-09-04]].

## How it felt

> "I feel slow and i feel like my breath is tighter. Felt like avg hr was higher for this pace. Otherwise i am glad that i did this."

## Comparison

| Metric | Aug 29 (comeback) | Sep 2 | **Sep 4 (today)** |
|--------|-------------------|-------|--------------------|
| Distance | 6.56 km | 3.01 km | **5.04 km** |
| Duration | 46:50 | 19:32 | **36:31** |
| Avg pace | 7'08" | 6'29" | **7'15"** |
| Avg HR | 157 bpm | 148 bpm | **159 bpm** |
| Max HR | 174 bpm | 163 bpm | **176 bpm** |
| Cadence | 152 spm | 166 spm | **156 spm** |
| VO₂Max | 46 | 46 | **46 —** |
| Sleep HRV | 106ms | 145ms | **111ms** |

**Verdict:** His felt sense is confirmed by the data, and it has a cause stack — not a fitness story. Two days ago (Sep 2, morning, 7h30 sleep, 145ms HRV) he ran 6'29" at 148 bpm. Today: 7'15" at 159 bpm — **46 sec/km slower AND ~11 bpm higher**. The inputs that changed: 5h45 sleep debt (the sleep note's prediction said exactly this — short sleep shows as elevated effort), ~28-29°C residual evening heat vs his usual morning slot, 68% more distance than the Friday plan's 3 km, and a 6'44" first km against the 7'30"+ anti-fade rule. The signature is nearly identical to the Aug 29 comeback run (7'08"/157) — but that one had active illness as the excuse; today's is sleep + heat + slot. What it is NOT: fitness loss. HR recovery was strong (175→134 = 41 bpm real 2-min drop despite the displayed 20), VO₂Max held at 46, and he finished 5 km he didn't have to start. The body's engine is fine; the day's conditions were just expensive.

One structural note, gently: today was the plan's *short and boring* Friday — 3 km easy, HR 135-150, existing to keep Sunday's legs fresh. 5.04 km with 25 anaerobic minutes is real stimulus the plan didn't ask for, 48h before the 6 km long run. Watch says 21h recovery, so Sunday survives fine — but km 3 at 7'55" is the fade signature the anti-fade rule exists to prevent. Sunday: first km 7'30"+ whether it feels slow or not, walking allowed, easy is the whole job.

## Connected

- [[Sleep/2026-09-04]]
- [[Runs/2026-09-02]]
- [[Half-marathon-plan]]