The 8 biomechanical metrics analyzed in real-time during your runs and their thresholds are set based on peer-reviewed academic papers and actual runner data.
📚 Research Evidence
Low cadence is associated with overstriding, which increases lower extremity injury risk.
- Luedke et al. (2016)
Confirmed reduced risk of tibial stress fracture with increased cadence - Kliethermes et al. (2021)
Increased risk of patellofemoral pain below 170 spm - Heiderscheit et al. (2011)
5-10% cadence increase reduces knee/hip load by approximately 20%
| Range | Status | Meaning |
|---|
| < 160 spm | Caution | Possible overstriding, increased impact |
| 160-169 spm | Room for improvement | Minor improvements can enhance efficiency |
| 170-185 spm | Optimal | Minimized injury risk, efficient running |
| > 185 spm | Normal | Elite level (individual variation exists) |
📚 Research Evidence
Shorter GCT is associated with running efficiency, while longer GCT increases braking force.
- Chapman et al. (2012)
Elite runners 155-200ms, recreational runners 200-280ms - Hasegawa et al. (2007)
Top marathon runners tend to have shorter GCT - Di Michele & Merni (2014)
Confirmed inverse correlation between GCT and running economy
| Range | Status | Meaning |
|---|
| < 250ms | Optimal | Efficient landing and takeoff |
| 250-280ms | Room for improvement | Some improvement possible |
| > 280ms | Caution | Increased braking force, reduced efficiency |
🏆When achieving elite runner standards (under 200ms), we provide feedback: "Elite-level landing!"
📚 Research Evidence
Excessive vertical movement wastes energy and increases landing impact.
- Adams et al. (2018)
5-10cm is optimal range, confirmed increased impact force above 10cm - Moore (2016)
Reduced vertical oscillation → improved running economy - Garmin runner data
Elite runners average 6-8cm, beginners average 8-12cm
| Range | Status | Meaning |
|---|
| < 8cm | Optimal | Efficient movement |
| 8-10cm | Room for improvement | Slightly bouncy |
| > 10cm | Caution | Energy waste, increased impact |
📚 Research Evidence
High landing shock rate (loading rate) is directly associated with lower extremity injuries.
- Johnson et al. (2020)
High vertical loading rate → 23-26%↑ patellar pain, 17-29%↑ plantar fasciitis - Davis et al. (2016)
Demonstrated effectiveness of real-time feedback in reducing tibial shock - Crowell & Davis (2011)
Confirmed reduced injury rates 6 months after loading rate reduction training
| Range (Score) | Status | Meaning |
|---|
| < 60 | Optimal | Smooth landing, minimal joint stress |
| 60-90 | Normal | Typical range for most runners |
| 90-110 | Warning | Increased shock, landing correction recommended |
| > 110 | Risk | High injury risk, immediate correction needed |
💡Landing shock is measured using AirPods accelerometer data and normalized to a 0-100+ scale. StrideCoach also tracks your personal baseline from initial runs to detect relative changes.
📚 Research Evidence
Head position affects whole-body posture, and inefficient posture also increases perceived exertion.
- Teng & Powers (2014)
Excessive trunk flexion increases hip/knee load; head position influences trunk angle - Schache et al. (2001)
Forward lean of 8-15° from vertical is associated with optimal running mechanics - Coaching consensus
Looking 15-20 meters ahead maintains natural head position and breathing
| Range | Status | Meaning |
|---|
| ±5° from neutral | Optimal | Natural forward gaze, relaxed neck |
| ±5° to ±10° | Room for improvement | Slightly lowered or tilted back |
| > ±10° | Caution | Neck/shoulder tension, possible breathing restriction |
📚 Research Evidence
Left-right asymmetry places excessive load on one lower extremity, increasing injury risk.
- Zifchock et al. (2006)
Confirmed increased injury risk when asymmetry exceeds 3% - Bredeweg et al. (2013)
Left-right asymmetry more commonly observed in novice runners - Haugen et al. (2018)
Elite sprinters show less than 2% asymmetry in ground contact time
| Range | Status | Meaning |
|---|
| 49-51% (±1%) | Optimal | Balanced running |
| 47-49% or 51-53% (±3%) | Room for improvement | Slight imbalance, monitor over time |
| <47% or >53% (>±3%) | Caution | Significant asymmetry, correction recommended |
💡Balance is displayed as left leg percentage (e.g., 48% L means 48% left, 52% right). Perfect balance is 50/50.
📚 Research Evidence
Lower stride variability indicates neuromuscular control and is associated with experienced runners.
- Nakayama et al. (2010)
Higher stride variability associated with increased fall risk and fatigue - Jordan et al. (2007)
Experienced runners show 2-4% CV in stride parameters vs 5-8% in novices - Hamill et al. (2012)
Moderate variability may be protective; extremely low or high variability both problematic
| Range (CV) | Status | Meaning |
|---|
| < 5% | Optimal | Consistent, controlled running |
| 5-8% | Room for improvement | Some variability, typical for recreational runners |
| > 8% | Caution | High variability, may indicate fatigue or instability |
📈Consistency naturally decreases (CV increases) as you fatigue. StrideCoach tracks this to detect when your form is breaking down.
📊 How It's Calculated
Form Score is a composite metric that combines all 7 individual metrics into a single easy-to-understand rating.
- Weighted combination
Each metric contributes based on its relative importance to injury prevention and efficiency - Dynamic adjustment
Weights adjust based on your pace—different metrics matter more at different speeds - Percentile ranking
Your score reflects where you stand compared to runners at similar paces
| Range | Status | Meaning |
|---|
| 85-100 | Excellent | Elite-level form across all metrics |
| 70-84 | Good | Solid form with minor areas for improvement |
| 50-69 | Fair | Several metrics need attention |
| < 50 | Needs work | Significant form improvements recommended |
🎯Focus on improving individual metrics that score lowest. Small improvements in weak areas have the biggest impact on overall Form Score.
Experience Science-Based Coaching
StrideCoach analyzes your form in real-time during runs and provides voice coaching
based on this scientific evidence.