When the body is healing from an injury (e.g., large scrapes on the body from falling on pavement at high speeds) should the body be more tired than usual? if so, why is that the case?

Tired: As a result of your massive scrapes your body may be more tired because of the trauma but also your body may be fighting off infection.

Yes: Often you have system wide inflammation going on that will make you feel exhausted. A large amount of your body's energy is going toward healing and the inflammatory response. Kinda like being knocked out by a virus with fevers and body aches.

Healing: There seems to be a relationship of fatigue to healing from any major injury or illness. I often look at it as though your body is shifting its energy toward the healing process and taking energy away from other activities.

More: More energy used to heal body and sometimes low grade infection which would make you feel run down.