FAQ · PACER AI Running Coach
Everything you might want to know about PACER — an AI-native running coach.
What is PACER?
PACER is an AI-native running coach (web app). At its core it is an AI agent that makes its own decisions — not a chatbot wrapper. It securely connects to your training data via the COROS MCP and builds on Daniels VDOT, Hansons cumulative fatigue and 80/20 polarized training to generate and dynamically adapt your personalized race training plan.
How is PACER different from a regular running app, or a ChatGPT wrapper?
Most running apps record and display data; chatbot wrappers can talk but also miscalculate and make things up. PACER is a disciplined AI agent: around the LLM it runs a self-built scheduling orchestrator (safety rails — excessive volume gets clamped back to science-based limits, and changes require your confirmation), a kinematics engine (pace and load computed deterministically in code), a sports-science knowledge base (RAG — injury/nutrition answers have sources) and a long/short-term memory engine (it remembers your old injuries and preferences). After every sync it re-reasons and outputs the best plan, review and pre-race analysis for right now — not a fixed template. Your condition changes — so does your plan.
Which devices and data sources are supported?
Currently one-click sign-in via the official COROS MCP, syncing training data from COROS devices (up to about 24 months of history). Your account password is never stored. More data sources are in the works.
What training science is PACER built on?
Jack Daniels' VDOT for fitness assessment and E/M/T/I/R five-zone pacing; Hansons cumulative fatigue for long-run and weekly-load design; 80/20 polarized training for intensity distribution and periodization; with reference to Banister TRIMP fatigue quantification and ACSM nutrition & hydration guidelines. See the training methodology.
Which runners and races is it for?
Runners with a concrete race goal: personalized training plans for 5K, 10K, half marathon and full marathon.
Does PACER cost anything?
It is currently free to use.
Can I run this model in my own AI tools?
Yes. PACER's three-layer decision logic is open-sourced as a Skill. In tools that support MCP/Skills (such as Claude or Cursor), point them at the repository (github.com/xiaolouJB/ai-running-coach), connect your COROS data, and you can generate the same training plans in your own environment.
How does PACER protect my data?
Data is read via official COROS MCP authorization; your account password is never stored. AI reviews and advice are based only on your real synced data — when data is missing it says so honestly and never fabricates mileage, pace, heart rate or medical diagnoses.