I exercise regularly, at home. I consider pull-ups and chin-ups to be the more important exercises in my regimen. Since I do strength training I tend to keep all exercises below 5 reps. When there came a point where I could do 4 sets of more than 5 reps per set of pull-ups and chin-ups I started putting weights in a backpack in order to increase the difficulty of the workout.
I've now reached a point where I lift myself 5 times (again 4 sets) with an extra 8.75kg(20lbs) on my back for pull-ups and 11.25kg(25lbs) for chin-ups. I've felt no side effects yet but still I feel like I need to ask in order to make sure I don't injure my back.
So, is what I'm doing a bad idea?