Kettlebells by their very nature have little eccentric loading unless you modify them. In the Kettlebell Jerk, especially for sport , you drop the weight into the rack as fast as possible with as little effort so as to not wear yourself down. This doesnt bode well for building muscle. But guess what? you can definitely accomplish building muscle with kettlebells . Heres how. You can do sets of eccentric focused jerk. By lowering the weight down either with a count or by breath duration. Either way, this can build mass or make it easier for You when You do regular lomg cycle or high rep clean and jerk . Enjoy and let me know if You try it!. Perhaps start with 10 sets of 5 reps? Joe.