Interesting thought Pumpit, I never thought about focusing on the negative movement on a pullup for gains. Would be interested in hearing anyone elses experiences with it (gains or lack thereof).
In reference to NickB ...
> What if you cant do a pullup?
When I started working out in my high school days I was 5'11" and about 170 lbs even after working out for a year and I still could barely only do one pullup (close grip underhander or overhanded) with much cheating even. My hips were just about as wide as my shoulders and I thought I was destined to failure when it came to any back growth.
I truly beleive that the body is an amazing piece of machinery and that it WILL ADAPT and OVERCOME just about any adversity. I was determined not to give up and find a way to widen my back and be able to do at least ten pullups no matter what I would have to endure (yes I know for some of you this is an easy feat but for those of us who couldn't do any in high school, 10 pullups is an enormous achievement).
The secret for me lay within a pullup itself. Yet I could only do at best one full complete pullup with cheating I find even small movements of the the lats and upper back were very beneficial.
I started by taking an overhand wide grip on a pullup bar (actually my first pullup bar was a 2x4 on the back side of a gazebo type structure) and go into a full hang making sure my feet were NOT touching the ground (legs usually bent at the knees). Next was to make contractions with my lats and back ONLY. My body would move upwards only slightly. Just enough to make sure the main muscle groups that were working were only in my back and lats. There was a tremendous burn and I could actually feel my lats (not arms) working. My goal was 50 reps total. Regardless of how many sets it took (yeah it took A LONG TIME IN THE BEGINNING) I stuck it out.
After acheiving 50 Lat-Shrugs (don't know if there is a more formal term for them but that is what I called them) I would go immediately and do some bb (barbell) bent rows. If you have never done bb bent rows start maybe with the bb bar only. Form is especially important in an exercise such as this where your lower back is put in a position that is very easy to injure if your roll your lower back out. Take a look at this link for proper form ...
http://www.exrx.net/WeightExercises/BackGeneral/BBBentOverRow.html
When I do my Bb bent rows I find it easier not roll my lower back if I keep my head looking upward as opposed to down as in the web demonstration.
Eventually after a couple weeks you should begin to notice that you will begin to be able to go a bit higher into your pullup contraction. Eventually you will be able to go all the way up and the temptation might be great to do the pullup to the front and touch your chest to the bar but I recommend you focus on touching the back of your neck to the bar, a WIDE GRIP BEHIND NECK PULLUP. A frontal pullup seems to involve the biceps and forearms a bit too much. Keep working on that total 50 number whether they are all Lat-Shrugs or Full Wide Grip Behind The Neck Pullups or a mixture of the two movements. Combined with bb bent rows I was able to acheive a much wider back (far wider than my waist now) and blow past the 10 pullup barrier.
Hopefully the above can be of some help to you NickB. Just remember hard work and determination are the only way you can acheive your ultimate goals. Are willing to go the extra mile? If so there is no limit to what you can acheive. Goodluck and much growth to you.
Note: Yes I was in high school and my body was still developing and maybe I still had some room yet to grow in my shoulders but even to this day at age 25 my shoulder width is far wider than both my younger brothers (23 and 21) whose shoulders are same width as their hips or smaller. I definately feel that wide grip behind the back pullups can create a wider flare and some degree of widening bewteen the shoulder blades.