The best way to do 20 pull ups is to be 5ft 2in.
I'd favour more volume than the AoM system suggests. Total thirty to forty reps per session.
As to increasing strength to achieve 20 pull ups. Strength is the ability to exert maximum force against a resistance, once. Doing it twenty times is endurance. Greater strength will make this easier, but going beyond ten reps is tiring until you train for it. Twenty reps of anything is tiring.
The best way to do 20 pull ups is to be 5ft 2in.
You just need to get your lifts up. Getting stronger will help the most. Those numbers are still very low. That and just doing chins will be the biggest help. I still can't do very many, but as my lifts went up, it became easier. This is with my weight increasing as well.
I'm confused by your numbers. You said you started out with the empty bar with the press, yet now you do 40lbs. An empty bar is 45lbs. Did you lose strength on the press? Also you said bench press was 20lbs starting out. Also how did you mistake between 90lbs and 175lbs in your deadlift? Can you please be more consistent?
Are you even counting the weight of the bar itself, or are you just counting the amount of weight you put on the bar? Because the weight of the empty bar still counts just as much as the weight you put on the bar.
In any case you're still pretty weak all around. So get all your numbers up. As far as doing more pull-ups, add in some negative reps. Don't do weighted pull-ups until you can complete at least 3 sets of 10 reps across.
Last edited by Keith; 02-01-2017 at 02:33 PM.