All StrideCoach feedback is based on peer-reviewed research and sports science. We transparently share why these numbers matter and what research supports them.
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.
Cadence
Steps per minute (spm)
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
Elite
Elite level (individual variation exists)
Ground Contact Time
Time foot is in contact with ground (ms)
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!"
Vertical Oscillation
Vertical body movement during running (cm)
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
Landing Shock
Impact force during landing (relative score 0-100+)
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.
Head Angle
Head tilt during running (degrees from neutral)
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
Left-Right Balance
Symmetry between left and right legs (%)
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.
Consistency
Stride-to-stride stability (coefficient of variation %)
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.
Form Score
Overall running form rating (0-100)
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.
Luedke, L. E., et al. (2016). Influence of Step Rate on Shin Injury and Anterior Knee Pain in High School Runners. Medicine & Science in Sports & Exercise.
Kliethermes, S. A., et al. (2021). Running Injuries and Biomechanical Risk Factors. British Journal of Sports Medicine.
Heiderscheit, B. C., et al. (2011). Effects of Step Rate Manipulation on Joint Mechanics during Running. Medicine & Science in Sports & Exercise.
Johnson, C. D., et al. (2020). The Association Between Running-Related Injury and Loading Rate. Sports Medicine.
Davis, I. S., et al. (2016). A Prospective Study of the Effects of Gait Retraining on Running-Related Injury Rates. British Journal of Sports Medicine.
Crowell, H. P., & Davis, I. S. (2011). Gait Retraining to Reduce Lower Extremity Loading in Runners. Clinical Biomechanics.
Adams, D., et al. (2018). Vertical Oscillation and Running Economy. Journal of Sports Sciences.
Moore, I. S. (2016). Is There an Economical Running Technique? A Review of Modifiable Biomechanical Factors. Sports Medicine.
Chapman, R. F., et al. (2012). Ground Contact Time as an Indicator of Running Economy. Journal of Applied Physiology.
Hasegawa, H., et al. (2007). Foot Strike Patterns of Runners at the 15-km Point. Journal of Strength and Conditioning Research.
Di Michele, R., & Merni, F. (2014). The Concurrent Effects of Strike Pattern and Ground-Contact Time on Running Economy. Journal of Science and Medicine in Sport.
Teng, H. L., & Powers, C. M. (2014). Sagittal Plane Trunk Posture Influences Patellofemoral Joint Stress. Journal of Orthopaedic & Sports Physical Therapy.
Schache, A. G., et al. (2001). The Coordinated Movement of the Lumbo-Pelvic-Hip Complex during Running. Gait & Posture.
Zifchock, R. A., et al. (2006). Kinematic Asymmetries in Recreational Runners with a History of Injury. Journal of Applied Biomechanics.
Bredeweg, S. W., et al. (2013). Differences in Kinetic Variables Between Injured and Noninjured Novice Runners. Journal of Science and Medicine in Sport.
Haugen, T., et al. (2018). Sprint Mechanical Properties in Handball and Basketball Players. International Journal of Sports Physiology and Performance.
Nakayama, Y., et al. (2010). Variability in Stride Interval during Continuous Running. Journal of Motor Behavior.
Jordan, K., et al. (2007). Walking Speed Influences on Gait Cycle Variability. Gait & Posture.
Hamill, J., et al. (2012). A Dynamical Systems Approach to Lower Extremity Running Injuries. Clinical Biomechanics.