Miles AI coaching
Can ChatGPT Be Your Running Coach?
Ask ChatGPT for a 12-week half marathon plan and you'll get something sensible in about ten seconds. Mostly easy runs. A long run that builds on Sundays. A tempo session midweek. A taper at the end. It looks like a plan from a running magazine, because that's largely what it learned from.
Plenty of runners stop there and follow it. Some do fine. The trouble usually starts in week four.
What it does well
Explaining things. What's a tempo run? Why does everyone talk about zone 2? What's the difference between a fartlek and intervals? ChatGPT is very good at this, patient, and available at 11pm when you're wondering if your calf is sore or injured.
A first draft. Give it real numbers and it produces a reasonable structure. The more you tell it, the better the draft.
Thinking out loud. "I've got a wedding on race weekend minus two, should I move my long run?" It's a decent sounding board. It will also, rightly, tell you to see a physio about the calf.
Where it falls apart
It can't see your runs. Unless you paste your data in every week, it's coaching a runner who doesn't exist. Coaching is mostly reacting to what actually happened. Without the data, there's nothing to react to.
It doesn't adapt on its own. Say you miss a week with a cold. The plan doesn't know. You have to notice, go back, explain, and ask for a rebuild. Most people don't. They just pick up at the week the calendar says, which is how a lot of injuries start.
It isn't there during the run. No pace cues. No "you're 20 seconds too fast, ease off." Nothing in your ear at kilometre 14 when it matters.
It forgets. Long chats drift. Ask for changes over several weeks and week 9 can contradict week 3. Mileage jumps that a careful coach would never allow can slip in without anyone noticing.
It can be confidently wrong. Paces especially. It will happily give you a tempo pace that doesn't fit your recent races. Always check its paces against a real, recent race time.
How to get a better plan out of it
If you're going to use it, give it what a coach would ask for. A good prompt includes:
- Your current weekly distance over the last four weeks.
- Your longest run in the last month.
- A recent race or time trial, with the date.
- Your goal race, its date and your goal time (or "just finish").
- How many days a week you can run, and which days.
- Any injury history.
Then ask it to keep weekly distance increases small, to show easy, tempo and long-run paces for each week, and to explain any week where volume jumps. Ask it to keep the hard sessions apart, never on back-to-back days.
Every Sunday, paste in what you actually ran and ask it to adjust next week. That's the manual version of what coaching apps do automatically. It works if you're disciplined. Be honest with yourself about whether you'll do it for twelve weeks.
ChatGPT vs a coaching app
 ChatGPT |
Coaching app (Runna, Miles, TrainAsONE) | |
|---|---|---|
| Cost | Free tier; paid plans | Free tiers; around $100-120 a year for full coaching in the US |
| Sees your runs | Only if you paste them in | Automatically, from phone or watch |
| Adapts after missed runs | Only if you ask | Built in |
| In-run coaching | No | Yes |
| Explains concepts | Very well | Varies |
| Remembers your whole block | Not reliably | Yes |
When ChatGPT is enough
Honestly, sometimes it is:
- You're an experienced runner who knows how to adjust a plan yourself and just wants a template.
- You're running a fun 10K with no time goal.
- You already have a structured plan and want help understanding it.
When a coaching app is worth it
- You have a race with a time goal.
- Your weeks are unpredictable and you'll miss sessions.
- You tend to run too fast and want to be told during the run.
- You want the plan to keep up with you without a weekly chat session.
There are free options. Garmin Coach is free if you own a Garmin. TrainAsONE has a free tier. Miles' free tier tracks runs and shows the plan it would build for you. The adaptive plan and live pace coaching are in Pro, at $14.99 a month or $99.99 a year in the US. Runna is the best known and costs $119.99 a year.
Our take
Use ChatGPT as a running encyclopedia. Use an app or a human as the coach. The two work well together. Ask ChatGPT why your plan has strides on Thursday, and let the app decide whether you do them.
Try Miles on iPhone
A 5K to marathon plan built from your current fitness, reflowed when runs get missed, with live audio pace cues while you run. Free to download.
