Some runs build fitness. Some runs build character. Today did both, with a salt-crusted side of humility.
This was supposed to be a standard Z2 aerobic run—low to mid Zone 2 for 70 minutes. The plan was simple: keep the HR in check, sip Nuun, munch some dates mid-run, and cruise along to the familiar hum of binaural beats through my Shokz. What I got instead? A case study in what happens when heat, humidity, and human error tag-team your long run.
Workout Plan vs. Reality Check
| Target | Actual |
| 7:13–7:40/km Z2 | 7:49/km (Z2-to-Z3 crossover) |
| 1:10:00 duration | 1:10:13 |
| HR in Low/Mid Z2 | Avg 143 bpm (Max 153) |
| IF target ~0.75 | IF 0.81 (overreaching) |
| Calories burned | 760 kcal |
| rTSS | 86 |
| Pa:HR | 14.35% 🔴 Major aerobic drift |
By the halfway mark, it felt like I was dragging a sweaty ghost version of myself. I tried to stay in Z2, but with each step, RPE crept upward. I had to walk to “reset” and hydrate. That helped—for a bit.
Conditions
- Time: 6:25 AM
- Temp: 25°C (felt like 27°C)
- Humidity: 77%
- Wind: Light W wind, 5.8 km/h
- Elevation Gain: 201 m
In short: this was a swampy slap in the face.
Fueling & Electrolyte Strategy
Pre-run:
- 2 tbsp Brain Octane MCT oil
- 250 ml regular Nuun
- 1 SaltStick chew
Carried:
- Small soft flask of Nuun (some leaked, then diluted)
- 4 pitted dates
- 2 additional SaltStick chews
During:
- Took chews and dates around halfway
- Hydrated as best I could—but the signs were there: rising HR, rising RPE, and eventually, rising nausea.
Post-run:
- Dizzy. Light-headed. Felt like I was orbiting my body.
- Sat down. When I stood? Bloodied elbow. I have zero memory of falling.
- Made it to the porta potty just in time for a GI evacuation of biblical proportions.
Bonus insight courtesy of Alex Hutchinson and exercise science: when we stop running, our calves stop pumping blood upward. If you’ve ever finished a race and then collapsed? That might be why. Lie down. Elevate your legs. Don’t argue. Just do it.
Lap Breakdown & NGP Highlights
The early splits were smooth. Then came the unraveling.
| Lap | Avg Pace | NGP | Avg HR | Notes |
| 1–3 | 7:21–7:10 | 6:56–6:47 | 131–144 | Felt strong, aerobic cruising |
| 4–5 | 7:58–7:35 | 7:49–7:23 | 142–146 | HR climbing, fatigue entering |
| 6–8 | 8:45–7:41 | 7:54–7:38 | 143–145 | GI issues & heat kicking in |
| 9 | 8:06 | 8:11 | 148 | Holding on |
| 10 | (0.03 km) | — | 142 | Stopped the watch post-walk |
Decoupling Pa:HR: 14.35%
That drift says it all. This run was a slow boil, and I stayed in the pot until the steam told me it was time to exit.
Lessons Logged
- More salt pre-run. I need at least 2 SaltSticks before running in these conditions, and a higher-sodium drink.
- Leak-proof bottle next time, please.
- MCT oil is okay in cooler weather, but I’ll rethink it for swamp days.
- Dates + heat = slow gut = no bueno. I’ll test gels or watered-down honey next hot Z2 day.
- Practice recovery posture. Sit, breathe, and elevate those legs when needed.
Final Thought
Not every run feels like a victory lap. Some feel like gritty rehearsals for when it all goes sideways—and that’s exactly what this was. A mental win. A humbling heat check. And a reminder that I don’t just run to be fast. I run to learn.
All training programs designed by Phil Mosely, available on the Training Peaks App.