The Speed Is Beginning to Show

Threshold Run — 30:11 | ~3.0 mi | 9:47/mi avg

Today was a threshold-focused run designed to put sustained work on the legs without turning the session into an all-out effort. The structure was simple: 5-minute walk, 5-minute easy jog, 10 minutes at threshold, 3-minute recovery, then another 10 minutes at threshold.

Once I settled into the first threshold interval, my pace came down into roughly the 8:00–8:20/mi range. The effort felt controlled initially, but my heart rate steadily climbed through the interval. The three-minute recovery brought it down significantly before the second threshold effort, where I was able to get back onto pace and hold it despite accumulating fatigue.

The conditions were a major factor: 82°F, feels like 85°F, with 71% humidity. The combination of heat and humidity made cooling difficult and likely contributed significantly to the HR drift. By the latter portions of the threshold efforts, my HR was reaching the low-to-mid 170s even though pace remained relatively stable. I spent 9:03 in Zone 4 and 4:53 in Zone 5.

The biggest takeaway isn't the overall 9:47 pace — the warmup and recovery make that number largely irrelevant. What matters is that I was able to sustain approximately 8:05–8:20/mi during the working portions in poor running conditions. I didn't fall apart during the second interval, and I was able to return to pace after recovery.

Strava also improved my predicted 5K to 26:17, down 1:40 after this run, and my estimated VO₂ max increased to 44. Both are encouraging signs that my aerobic fitness and running performance are moving in the right direction — particularly because this wasn't a 5K time trial and the weather was far from ideal. More importantly, those improvements came from a structured threshold workout in 82°F heat and 71% humidity, not from a rested race effort in ideal conditions.

Takeaway: The speed is beginning to show. Now the goal is to build durability around it. I don't need to force the threshold pace lower yet. I need to make this pace increasingly controlled, extend the amount of time I can sustain it, and continue developing the aerobic engine that will eventually let me run efficiently after 56 miles on the bike.

Next benchmark: Repeat 2 × 10 min at ~8:05–8:20/mi in cooler conditions and compare HR response. From there, progress toward 2 × 12–15 minutes at threshold.

Current benchmarks: VO₂ max 44 | Estimated 5K 26:17 | Threshold pace approximately 8:05–8:20/mi

Tri For the 22 — Movement Creates Momentum.