SKILL.md
Biomechanics Validation
When reviewing jump metrics, validate against these norms:
RSI (Reactive Strength Index)
| Population |
RSI Range |
| Recreational |
0.5-1.5 |
| Trained |
1.5-2.5 |
| Elite |
2.5-3.5 |
Flag values > 3.5 as potentially erroneous (measurement or technique issue).
CMJ Jump Height
| Population |
Male (cm) |
Female (cm) |
| Recreational |
25-40 |
20-35 |
| Trained |
40-55 |
35-45 |
| Elite |
55-70+ |
45-55+ |
Ground Contact Time (Drop Jump)
| Range |
Interpretation |
| < 100 ms |
Likely sensor/detection error |
| 150-250 ms |
Optimal reactive strength |
| 250-350 ms |
Acceptable, technique improvement possible |
| > 400 ms |
Technique issue or fatigue |
Flight Time
| Jump Type |
Typical Range |
Flag If |
| CMJ |
400-600 ms |
> 800 ms |
| Drop Jump |
350-550 ms |
> 700 ms |
Triple Extension (CMJ)
All three joints should approach full extension at takeoff:
- Hip: > 160° (optimal: 170-180°)
- Knee: > 160° (optimal: 170-180°)
- Ankle: > 130° (plantar flexion)
Countermovement Depth (CMJ)
| Depth |
Interpretation |
| < 20 cm |
Shallow - may limit power generation |
| 20-40 cm |
Optimal range |
| > 50 cm |
Deep - may indicate technique issue |
Validation Response Format
When validating metrics, provide:
- Status: Normal / Warning / Error
- Value: The actual metric value
- Expected Range: Population-appropriate range
- Interpretation: Coaching-friendly explanation
- Recommendation: If outside norms, suggest next steps
Example Validation
RSI: 2.8
Status: Normal (Elite range)
Expected: 2.5-3.5 for elite athletes
Interpretation: Excellent reactive strength capability
Ground Contact Time: 85 ms
Status: Warning
Expected: 150-250 ms optimal
Interpretation: Unusually short - likely detection error
Recommendation: Review debug video for takeoff/landing detection accuracy
