ChatGPT vs Runna: which one should coach you?
I train with Runna, and I ask Claude and ChatGPT about my training every week. So when people ask whether ChatGPT can replace Runna, my answer is that they don't do the same job. Runna tells you what to run. An AI that can read your watch tells you what happened when you ran it.
What Runna does that ChatGPT can't
Runna builds a plan towards a race, puts each session on your Apple Watch as a structured workout, and tells you in real time whether you're on pace. That last part matters more than it sounds: a plan you can follow without looking at your phone is a plan you actually follow. ChatGPT can write a plan, but it can't put a workout on your wrist or buzz when you drift off pace.
What ChatGPT does that Runna doesn't
Here is the session Runna gave me on October 9: a descending set of 2 × 1 km, 2 × 800 m, 2 × 600 m and 2 × 400 m, with 90 seconds of walking between reps. On the 600s my watch kept telling me I was behind, then ahead, then behind. The surface was gravel and the wind was in my face. It felt like I'd failed them. Afterwards, I asked:
How did today's Runna session go against the targets?
healthsync · get_workout 19 legs · 9.48 km · 52:55
On plan, and the one miss isn't yours. 1 km reps in 4:25 and 4:29 for a 4:30 target, 800 m in 4:26 and 4:23 for 4:25, 400 m in 3:56 and 4:05 for 4:10. Only the 600s missed, 4:19 and 4:22 for 4:15, yet you held 338 and 332 W on them, the same as the 800s at 346 and 329 W: the effort was there, the gravel and the wind took the pace. Heart rate came down to between 98 and 112 bpm in every 90-second walk, the last one included. A hard session done right.
Runna's summary showed me each rep against its target. What I wanted to know was why the 600s missed, and that takes reading more than pace. With the watch's running power for each rep next to its pace, the answer is plain: same output as the 800s, slower over the ground: the terrain, not my legs. So next week's plan doesn't need to change.
Side by side
| Runna | ChatGPT or Claude, reading your workouts | |
|---|---|---|
| Builds a plan towards a race | Yes | Yes, better once it can read what you ran |
| Puts the session on your watch | Yes | No |
| Pace cues during the run | Yes | No |
| After the session | Each rep against its target | Any question your data can answer: why a rep missed, how it compares with last month |
| What it reads | Your runs | Everything Apple Health holds: runs, rides, swims, sleep, resting heart rate |
Can ChatGPT replace Runna?
If what you want is a free plan, ChatGPT will write one, and it will be decent if it can read your recent runs; here's why it needs to. You'll then build each workout on your watch yourself, and run without pace cues unless you set them up. Some people are happy with that.
If you want the plan to run itself, keep Runna, and add the AI as the part Runna doesn't have: someone to ask after the session. Runna writes the workout, the watch records it, and the assistant reads it. That's the setup I use.
HealthSync is how the assistant reads it: it syncs every Apple Watch workout, Runna's included, and lets Claude or ChatGPT read them rep by rep. I built it for exactly this question.
Try it on your own workouts
HealthSync is on TestFlight now and on the App Store soon. Leave an address and we'll send the link.