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Nordic hamstring — three lenses
Symmetry alone clears athletes who should not be cleared. Enter one set of numbers and see all three checks that the research actually supports.
Why one number is not enough
Symmetry can be perfect and still wrong
Two limbs at 300 N each give a limb symmetry index of 1.000. Nothing about that number tells you both hamstrings are weak — and under roughly 337 N the published hamstring-injury risk is around four times higher.
Newtons per kilogram misranks heavy athletes
Dividing force by body mass makes every large athlete look weak. The relationship is not proportional: expected force is about 4 N per kilogram plus a fixed 26.1 N. A 95 kg centre-back and a 65 kg winger are not judged the same way, and they should not be.
The gates are 0.90 and 0.95, and they are not a clearance
0.90 to progress a rehab stage, 0.95 to discharge. Both are one lens of a battery. No symmetry number on its own returns anybody to play.
Tracking this across a season
Priveo stores every test against the athlete’s own baseline, so a 6% drop from their personal normal is visible even while they still pass every population threshold.