Just to give you a story about pull up bars.... a couple years ago a sleep nurse in my department had a son that wanted to join the Marines. He could do the pushups, the situps, the running, etc.. but could not do a single pullup to save his life. Some may say it was due to his bodyweight (170lbs at 17 yo), or because he had not master the "technique" of doing a pull up and was trying to use his biceps too much and not activating the back muscles... whatever.
What this kid did was buy a pull up bar and attach it to his bedroom/bathroom door. Every time he crossed that doorway, he did pullups. Go to the bathroom, do a pull up, leave the bathroom, do a pull up. It took a couple of weeks before he could do a single one that was complete. Months went by and he got better to where he would do 5 or so at time. It doesn't sound like 5 pullups are much... but he was doing 5 reps every single time he went in or out of that door. Had to be about 20 times a day. He made sure he did strict, perfect reps. When it came time for the Marine physical, he was able to bang out what they wanted by loosening is form up too.
I saw this kid before he went away and doing those pull ups each day had a direct affect on his back muscles. They were more developed than anything else.
Just sharing this because some of you may want to try it. Or if you are spending time playing games online, in between matches, do pushups or crunches. There is always something you can do to stay active.