Bad Back
For whatever reason, your spinal column is in bad shape. During strenuous physical activity, you may "throw your back" and suffer crippling pain or further injury. Whenever you make a ST roll, and whenever you roll 17 or 18 on an attack or defense roll in melee combat, or on a roll for an "athletic" skill such as Acrobatics, make a HT roll as well.
Modifiers: Any modifiers to the success roll for the activity that triggered the HT roll. For a long task that allows the luxury of planning, you can try to minimize the strain on your back; a successful IQ-2 or Physiology+4 roll gives +2 on the HT roll.
On a failure, you throw your back. Consequences depend on the severity of your case:
Mild: You are at -3 DX until you rest or someone helps you; a First Aid-2 roll will reset your back. You are also at -3 IQ, but during the next second only (for your next turn, in combat). On a critical failure, you are at -5 DX and must make a Will roll to perform any physical action. -15 points.
Severe: The HT roll is at -2. On a failure, DX and IQ are both at -4 until you receive rest or help; you are in constant agony. On a critical failure, you take 1d-3 damage and are at -6 DX and -4 IQ. -25 points.
High Pain Threshold halves all DX and IQ penalties (drop fractions), but does not eliminate them completely.