We ran a MARATHON on a treadmill (very hot!) - This Messy Happy

Aug 13, 2025

Intro: This is a quick summary of We ran a MARATHON on a treadmill (very hot!) from This Messy Happy. It’s a great watch — we’re breaking it down so you can try the workout today. Be sure to check out the full video for all the details.

Key Points:

The marathon was split into consecutive 5 km (5 k) treadmill runs, with one partner swapping in as the other stepped off the belt.
Running indoors without a fan felt hotter, so heart‑rate zones jumped (zone 2 quickly turned into zone 3/4).
Aiming for a 5‑minute km pace (≈12 min / mile) was realistic outdoors but felt tougher on the treadmill.
Hydration was critical – the runner walked off‑tape to grab water and avoid dehydration.
Mental focus and a “rhythm‑mindset” helped the later segments feel easier than the first.

Workout Example:

Warm‑up 5 min easy on the treadmill.
Run a 5 km block at ~5 min/km (or your own comfortable effort).
At the end of the block, step off, quickly grab a drink, and let the next runner hop on to continue where you left off.
Repeat the 5 km blocks until you total ~42 km (marathon distance).
If heart‑rate spikes above your zone 2 (≈164 bpm for the video’s runner) or you feel a stitch, walk briefly to hydrate and reset before resuming.

Closing Note: Give yourself a marathon‑sized challenge by chunking the distance into 5 km segments, monitoring heart rate, and staying hydrated – then celebrate the finish! You can easily customize the paces and breaks in the Pacing app to match your own fitness level. Have fun, push your comfort zone, and enjoy the run! 🎉