[Thinks for a bit. Can't tell if JonanHex agrees with Union or not.]
Strain's a weird beast either way.
Species statistics and the Obligation mechanic back up the theory that it represents confidence/determination and mental forcus. That unarmed attacks still do Wound damage rather than Strain (if you're not a Doctor with the Pressure Points talent) also backs this up...
but then Stun weapons depleting Strain cuts the arguement off at the knees (they depress you into unconsciousness?).