Full-Body Analysis
From Head Motion
Our patented BiomechEngine® reconstructs your entire running form
using only the motion sensors in your AirPods — no cameras, no pods, no guesswork.
The Science of Head-Body Correlation
When you run, your head doesn't move independently — it responds to every footstrike, every imbalance, every change in posture. This biomechanical coupling is the foundation of our technology.
Beflex was founded in 2016 by researchers from KAIST (Korea Advanced Institute of Science and Technology) with a singular mission: to develop the world's first biomechanics solution that extracts accurate running form data from head motion alone.
Years of research validated the correlation between head motion patterns and full-body running mechanics. Our findings — verified against professional motion capture systems — show that head movement can reveal:
- Ground Reaction Force — Impact transfers through the body to the head
- Left-right asymmetry — Imbalances cause detectable head tilt patterns
- Cadence and rhythm — Each step creates measurable oscillation
- Vertical bounce — Inefficient form shows in head trajectory
- Stance and flight time — Gait phases are reflected in head motion
This patented approach is why AirPods — worn on your head — can deliver lab-grade running analysis without cameras, foot pods, or chest straps.
Peer-reviewed validation: BiomechEngine accuracy has been verified against motion capture systems and force plate treadmills in published research. Learn more →
Head Motion
correlates to
How It Works
From raw sensor data to voice coaching — in milliseconds.
Capture
AirPods motion sensors detect head movement at high frequency
Infer
BiomechEngine® reconstructs full-body running dynamics from head motion
Analyze
AI evaluates 8 biomechanical metrics against research-backed thresholds
Coach
Real-time voice feedback guides you to better form instantly
BiomechEngine®
Our patented biomechanics algorithm transforms raw accelerometer and gyroscope data into over 100 comprehensive motion metrics, including Ground Reaction Force (GRF) and advanced gait parameters previously only available in research labs.
Co-developed with biomechanics researchers, BiomechEngine delivers lab-grade precision rivaling professional motion capture systems — using nothing more than consumer earbuds.
Analysis happens instantly during your run, not after
Benchmarks adjust to your pace and running style
All processing happens locally on your iPhone
Verified against motion capture and force plates
8 Biomechanical Metrics
From over 100 data points, we surface the 8 metrics most relevant to runners.
Each is backed by peer-reviewed research and validated against professional motion capture.
Cadence
Steps per minute
Ground Contact Time
Landing duration
Vertical Oscillation
Up-down movement
Shock
Landing impact force
Head Angle
Posture alignment
L/R Balance
Symmetry analysis
Consistency
Stride stability
Form Score
Overall rating
Intelligent Voice Coaching
Raw metrics alone don't help mid-run. Our voice coaching engine decides what to say, when to say it, and how to say it — so you get actionable guidance without information overload.
Most important corrections first; minor issues wait
Won't repeat the same cue too frequently
Conversational cues, not robotic announcements
Localized coaching in your preferred language
Heart Rate Integration
When paired with Apple Watch, StrideCoach adds heart rate data to the mix. Train by HR zones, get voice alerts when you drift out of target, and run completely phone-free.
Privacy by Design
Your running data never leaves your device. All analysis — from raw sensor processing to voice coaching decisions — happens entirely on your iPhone.
No cloud processing, no external servers
Start immediately, no signup needed
Only motion data is used, never audio
Full privacy protection worldwide
Experience the Technology
Put on your AirPods and start running. Feel the difference
of having an AI coach analyzing your form in real-time.