Working out a muscle make it prone to injury?

Factual Questions
1

I have a muscle pull (or something) in my lower back that I got this weekend by moving a heavy box. I have never had back injuries my entire life until the last 12 months; this is the third. (The first one I don’t know what caused it, the second followed slipping on ice.)

Coincidentally, about a year ago I started adding lower back exercises into my weight training routine (I have been doing weight training for about 25 years). I do a relatively lightweight routine, whole body about three times a week, doing multiple sets only on about three exercises each time, rotating. I just don’t have the time for a heavier routine, split sets, etc., etc. The lower back exercises are done on a machine.

So at any given time, my back is recovering from a workout. Does that make it more prone to injuries? I don’t seem to have this problem with any other muscle.

2

I’ve never heard anything to that effect. I would be more concerned about your day-to-day habits, particularly your seated posture, as a source of lower back injuries.

3

Muscle fatigue can apparently interfere with proprioception, which could lead to injury. http://www.eorthopod.com/public/patient_education/5495/the_role_of_muscle_fatigue_in_knee_injuries.html

The study cited, though, talks about immediate muscle fatitue, and not muscles recovering from fatigue or delayed onset muscle soreness. Then again, if you have DOMS, it might cause you to try to compensate, which might cause you to hurt your back.