Comparison
STAS vs Runna — which AI running coach fits you?
Two different approaches to AI coaching. One gives you structured plans in a polished app. The other connects ChatGPT to your real training data. Here's an honest look at both.
What is Runna?
Runna is a popular AI running coach app that generates structured training plans based on your goal race, current fitness level, and available days. It integrates with Garmin, Apple Watch, and Strava to pull in your workout data and adjust plans accordingly.
The app is known for its clean interface, well-organized training calendar, and guided workouts. It works best for runners who want a ready-made plan they can follow without much deliberation. Runna is a paid subscription service, typically around $15/month.
What is STAS?
STAS is a ChatGPT-powered running coach that connects directly to your Intervals.icu account. Instead of generating a fixed plan, it reads your actual training history, HR zones, pace data, fatigue metrics (CTL/ATL/TSB), and subjective reports to provide personalized coaching through natural conversation.
You can ask STAS anything — why a particular workout is prescribed, how to adjust after illness, or what your training trends look like. It adapts in real time based on what you actually did, not just what was planned. STAS has a free tier available.
Side-by-side comparison
Runna
- Approach
Mobile app with structured training plans and guided workouts - Data source
Garmin, Apple Watch, Strava sync - Plan adaptation
Weekly plan adjustments based on completed workouts - Conversation
No free-form chat with the coach - Life context
Limited — select from predefined options - Price
~$15/month subscription - Explainability
Limited — follow the plan as given - Best for
Beginners wanting clear structure and guidance
STAS
- Approach
ChatGPT conversation powered by your real training data - Data source
Deep Intervals.icu integration (HR, pace, CTL/ATL/TSB, laps) - Plan adaptation
Real-time per-workout adjustments based on actual performance - Conversation
Full natural language — ask anything about your training - Life context
Understands illness, travel, fatigue, schedule changes - Price
Free tier available - Explainability
Ask "why this workout?" and get a detailed answer - Best for
Data-driven runners who want control and transparency
When Runna is the better choice
Runna is a strong option if you value a polished mobile experience and prefer following a structured plan without much back-and-forth.
- •You want a clean, guided app experience with workout instructions on your wrist
- •You're new to running and prefer a plan you can follow without decisions
- •You don't use Intervals.icu and sync primarily through Garmin or Strava
- •You prefer a visual training calendar over conversational coaching
When STAS is the better choice
STAS is designed for runners who already track their data seriously and want a coach that truly understands their training history.
- ✓You already use Intervals.icu and want your coach to read all your data
- ✓You want to ask questions, discuss strategy, and understand the reasoning behind each workout
- ✓Your schedule changes often — illness, travel, variable workload — and you need real-time adaptation
- ✓You're an experienced runner who wants coaching depth, not just a plan to follow
Frequently asked questions
Can I use both Runna and STAS at the same time?
Technically yes, but it's not recommended. Following two different training plans simultaneously creates conflicting load and recovery signals. Pick one approach and stick with it for at least a training cycle.
Does STAS work without Intervals.icu?
Intervals.icu is the core data source for STAS. Without it, STAS can't access your training history, HR zones, or performance metrics. If you use a Garmin, Wahoo, or other device, you can connect it to Intervals.icu for free — it takes about 2 minutes.
Is Runna better for beginners?
Runna's structured approach with guided workouts and a clean app interface can be more approachable for beginners. STAS is more powerful for runners who want to go deeper, but the conversational format works well at any level — you just ask simpler questions.
Why is STAS free when Runna charges $15/month?
STAS runs on ChatGPT (you need a ChatGPT subscription) and connects to your data through Intervals.icu. The coaching intelligence comes from the AI model you're already paying for. STAS provides the data bridge and training logic on top.
Related
Ready to try a different approach?
Connect your Intervals.icu account and start coaching with ChatGPT — powered by your real training data.
Try STAS freeFree to start. No credit card required.