Pavel did a study with Stu Mcgill that found 150 percent activation of his lats with a 1 handed swing. Does anyone know the lat activation for a 2 handed swing
Sorry for the long winded response, I'll begin with I do not know what the percent activation of two handed swings is and I'm not sure if I even connect with the language of "150% activation," I dont really know what that means, but I will relay what I do know.
When I went thru the kettlebell instructor cert, run by Jon Engum, at the Five Points Academy in NYC, some 18 months ago, we did A LOT of two handed swings. At some point late in the afternoon of the second day I felt something that I had never felt before in my kettlebell practice. Complete and full connection with my lats during a two handed swing. I had done tens of thousands of two handed swings in the years leading up to the cert. I went thru the "Dan John 10,000 swings in a month challenge," three times and I had done countless swings beyond those challenges. On top of that, I consider myself a technique freak and I did all I could to drill the proper form and never get sloppy with my practice.
But something special happens at the StrongFirst Kettlebell Instructor Cert - first of all you are surrounded by instructors and some of the fittest people you will ever meet outside of a pro sport setting. At my cert there were two lead instructors and then we broke off into teams and my team had a head instructor and three to four assistant instructors - there were probably 10-12 students on my team - so it is rare not to have a set of eyes on you and some one giving you specific feedback on how to improve. The finest details are given the utmost importance. On top of that you are learning to become an instructor, so you are instructing as well. There are so many layers of learning taking place. You almost cant imagine how effective that is without going through it yourself.
During this experience you will come to a point where you lock-in to a near perfect swing, because if it isnt near perfect an instructor will direct you to park the bell, provide you with feedback and watch as you swing again. Park it, get feedback, perform the exercise. Over and over and over ... and at some point during those sessions you will feel it. Maybe it's the perfect packing of the shoulder, maybe its just the right amount of tension on the hamstrings, maybe its the float where the whole room seems to be halted in suspension, and maybe its that feeling of a full and complete lat activation from insertion point on the upper arm to origin on the pelvis. Once you feel that, you never forget what it feels like. You wont always replicate it, but you know when you do and you'll know how to get there.
I'm not sure where your question is leading - typically these questions are trying to determine whether one exercise is "more effective" than another, and thats a valid line of questioning to explore. But, no matter what the answer is, maybe the two handed has 75% activation, maybe 250%, again the numbers dont connect with me, the key takeaway is that both exercises, 1H and 2h swings are key components of the StrongFirst paradigm.
Is one better than the other? Yes. Which one is better? It depends.