I bet he regrets introducing him to Krav Maga:
http://en.wikipedia.org/wiki/Krav_Maga
This could explain Sheri's injuries.
These include a variety of fast and fluid crippling attacks to vulnerable body parts through various efficient and often brutal strikes. The improvised use of any available aids is encouraged - maximizing personal safety in a fight is emphasized. Krav Maga training programs involve rapid learning, with offensive and defensive techniques introduced from the first lesson and
retzev (pronounced ret-zef and meaning "continuous motion or momentum") playing an important part in both training and maneuvers.
[8]
While no limits are placed on techniques to be used in life-threatening situations, during training the legal need to minimize damage is generally stressed (at least in civilian contexts, and instructors are required to demonstrate how to moderate the techniques to suit the seriousness of the circumstances.
Krav Maga basic training emphasizes the following:
- Do not get injured or injure training partners.
- Employ pre-emptive defensive techniques
- Change quickly from defensive into offensive techniques i.e. respond to an attack with overwhelming force, in the quickest time possible
- Use the most natural, quickest, reflexes of the body
- Exploit the opponent's vulnerabilities to their extreme
- Employ the aid of any available objects[7]
