I Got an AI Personal Trainer for $0. Now I’m an Ironman.
April 2026. Every run ended with my heart rate at 170 bpm. My bike had been sitting in the basement since winter. I was terrified of open water swimming… and Enea IRONMAN 5150 Poznań was just around the corner.
Setup: three tools, zero code
The connection is simple:
Strava automatically records every workout through my watch.
GetFast pulls that data and shares it with Claude via MCP. Claude sees every activity in real time and can analyze it on the spot.
No code. No databases. No rulebooks. All it took was one sentence at the start: “I want you to be my personal trainer. Here’s my goal…”
And that’s how our collaboration began.
What “AI sees everything” actually means
This isn’t a chatbot that answers questions. It’s something different.
When I came back from a run and typed “check my last workout” Claude literally pulled the data from Strava: distance, pace, heart rate, time, elevation profile. I didn’t describe what I did. It saw it for itself.
That changed the entire dynamic. I couldn’t say “it was an easy run” when the data showed 170 bpm. I couldn’t pretend everything was going to plan when it could see a week with no cycling. The AI was like a coach standing at the track watching-not one who takes your word for it 😄
A few weeks after I said “I’ll get back on the bike in May, it’s still too cold” and actually did it simply replied: “A man of your word. Respect.”
Two minutes later I had my plan for the next week.
The biggest lesson: slow down to run faster
For the first few months, Claude kept telling me the same thing: I was running too fast.
170 bpm on a comfortable 10 km run is race pace, not training pace. Long-distance events require months of work in Zone 2 for me, 130–140 bpm where the body builds aerobic capacity instead of burning itself out.
The problem was mental. Running at 8:00 min/km felt like going backwards. Claude had one answer:
“It’ll be boring. You won’t sweat. You’ll feel like it wasn’t a real workout. And yet it will be the most important run of the week.”
He was right. The first run at 138 bpm after weeks of nudging was a turning point.
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By the time Poznań came around, my heart rate on long runs had dropped from 170 to 152 bpm at the same distances. Aerobic fitness was growing, even when I couldn’t feel it day to day.
The numbers after 5 months
- 691 km run
- 736 km on the bike
- 67 km in the pool
- ~145 hours of total training
Nearly 1,500 km in five months. With a full-time job, a normal life, and zero prior triathlon experience.
Open water destroyed me (and that was the plan)
First open water session: 860 meters, 158 bpm, I got out after 24 minutes feeling like the water had beaten me.
Claude didn’t change the plan. He said that’s exactly why you do it before race day, not on race day. Every session after that was better. Before Poznań, I swam 1,400 meters in a lake at 149 bpm feeling completely at ease.
“This is a completely different person from the one who got out after 860m three weeks ago feeling like the water had won.”
Race day
August 30, 2026. Poznań.
I finished Enea IRONMAN 5150 Poznań exactly on the time we had planned together. A few minutes after crossing the finish line, I messaged Claude. The reply was short:
“I’m proud of you too.”
Why this works better than you’d expect
A human coach sees you once a week, if you’re lucky and can afford it.
Claude saw every single workout over 200 activities across five months. It knew when I was overtrained before I admitted it myself. It caught that my “easy run” had actually finished at 164 bpm. It remembered I promised to get back on the bike in May and held me accountable in June.
This isn’t a chatbot that motivates you. It’s a system that has your data and uses it to help, not just to cheer.
How to replicate it
Four steps:
- Create an account at claude.ai
- Record your workouts via Strava
- Connect Strava to GetFast (getfast.ai) and GetFast to Claude (Settings → Integrations)
- Write: “I want you to be my personal trainer. My goal is: [your goal]. Check my recent activities.”
The rest takes care of itself. Good luck.
Maciek accidental triathlete, marathon runner in progress.
