Here Comes the Sun – Peak Phase 2 | Week 1 | Run 4 (Aerobic Endurance)

My Road to TOWaterfront 42K

This was a fasted, pre-sunrise easy run with my lighting rig.

I haven’t run in the dark in quite a while, so I was a bit nervous about footing – running through pools of light followed immediately by spans of inky shadow. It was a fairly strong run. However, while at an event about an hour after the run, I felt lightheaded and off. Even after a filling brekkie and back at home, I crashed medium-hard into bed. Then the insatiable thirst hit me. After many rounds of electrolytes, water, and soda water, I checked the humidity at the time of my run – 95%! Sneaky b@st@rd! I thought I was getting sick!

📊 Metrics 

EF calculation: ( \text{EF} = \frac{\text{NGP speed} \times 60}{\text{avg HR}} ). Using NGP 6:54/km and avg HR 142 → 1.02.

🔍 What the Numbers Say

• Pa:HR 6.97% → mild aerobic drift in oppressive humidity; still within acceptable range for an easy Z2 aerobic outing.
  
• IF split 0.86 (pace) vs 0.74 (HR) → mechanical effort outpaced cardiovascular strain, a good sign of durability with humidity capping HR.
  
• EF 1.02 → in line with recent easy-run trend-economy holding steady despite sticky air.
  
• Cadence 165 spm → right in your easy sweet spot; footing vigilance didn’t degrade rhythm.
  
• VAM 208 m/h → rolling work stayed honest without HR spikes.
  

🎯 Coach’s Corner

Did I Hit the Targets?

• Intent: ~45–60 minutes of steady Z2 Aerobic Endurance.
  
• Execution: ✔️ Steady Z2 throughout; perceived “post-run crash” reads as under-hydration from 95% humidity, not illness.
  

Why it worked / What to tweak:

• In humidity >90%, sweat doesn’t evaporate-cooling stalls and fluid loss sneaks up even at easy paces. For future dawn Z2 runs >45 min, pre-load 250–350 ml electrolytes and sip every 10–12 minutes (fasted is fine; “dry” is not).
  

🧭 Takeaway

I kept it easy, stayed smooth in the dark, and learned (again) that when the air is a sponge, hydrate like it.