Two weeks of training. No standalone Zone 2 run.
Week 3 fixed that. Here’s how it went — including a back injury, a heat warning on the track, and a benchmark test that got deferred.
The Breakthrough Session
Monday June 22nd. I switched what was supposed to be an interval session to a Zone 2 run because my legs were too tired from the previous week to hold quality interval pace.
Best decision I made all week.
6km on the treadmill at 6:13/km. Nasal breathing only. Average HR 132 bpm. Zone 2 time: 35 minutes out of the session. Zone 3+: essentially zero.
That’s what a Zone 2 run is supposed to look like. HR stable in the aerobic window the entire time, no drifting into high intensity, genuinely easy effort that feels almost too slow. It felt like I wasn’t working hard enough. That’s exactly correct.
6:13/km is now my established Zone 2 pace. That number will get faster as the aerobic base builds. The goal isn’t to run this pace faster right now — the goal is to accumulate time at this HR, week after week, until the aerobic system adapts and 6:13/km becomes 5:45/km at the same heart rate.
That adaptation is what makes 4:00/km race pace feel sustainable instead of maximal.
The Heat Warning
Wednesday June 24th. I took the intervals to the track instead of the treadmill. 93 degrees outside.
First four reps: 4:26, 4:25, 4:32, 4:40/km. Solid. Then on rep five — I felt cold.
Feeling cold when it’s 93 degrees outside is not good. It’s an early heat exhaustion warning. I backed off immediately and jogged the final two reps. Correct decision. The HR data confirmed it — Zone 4+5 combined was 56% of the session, and I was within 1 bpm of my max heart rate during the backed-off reps.
Hyrox training tip: do not run intervals outside in Florida summer. The heat adds 20-30 seconds per kilometer to any effort and creates genuine health risk at max intensity. Intervals belong on the treadmill in summer. Zone 2 runs can go outside in the evening when it’s cooler.
The Back
Saturday of Week 2 I tweaked my lower back doing Bulgarian split squats with 70lbs and side lunges with 53lbs at a bootcamp. The tweak carried into Week 3.
The back response: no heavy loading, no sandbag carry, light movement only. Running was fine — easy forward movement doesn’t compress the spine the way loaded squats do. The 10km long run on Friday felt completely okay.
By end of Week 3 the back was settling. No nerve symptoms, no radiating pain. Muscular. Manageable.
What Got Skipped
Benchmark tests — 1km time trial, 2000m row time trial, 80m burpee broad jump — were scheduled for Tuesday. Back soreness pushed them to the following week. Then a family trip to Indiana pushed them further.
I was out of structured training from roughly June 26th through July 4th. Solo parenting, travel, life. The plan hit its first real disruption.
What Week 3 Taught Me About Hyrox Training
The Zone 2 run is the most important session in any Hyrox training plan — and it’s the easiest one to skip because it doesn’t feel hard enough to count. Group classes feel productive. Zone 2 runs feel like a jog.
But the 35 minutes of Zone 2 I built on Monday was the most valuable training I’d done in three weeks. That session is the foundation. Everything else — intervals, station work, race simulations — is built on top of it.
If you’re putting together your first Hyrox training plan: schedule your Zone 2 runs first. Protect them like they’re the most important sessions of the week. Because they are.
— Austin