(Thank you to Francheska for the great question)
Can I keep the muscles that I built through bodybuilding style training when I move to solely kettlebells and bodyweight training?
Short answer: no
Kettlebell training and bodybuilding training have very different objectives.
Bodybuilding is first and foremost about the appearance and aesthetic proportionality of the muscles. The strength, mobility and endurance that might come with that is incidental – function follows form.
In bodybuilding, you look at your body, and, with an ideal or ‘better’ look in mind, you do exercises that increase the size of this or that muscle, so your body looks closer to that ideal.
Bodybuilding has visual trends the same way that beauty industry has trends. Smaller waist or thicker waist, bulging shoulders or pumped chest, more size in legs or arms, slim look or pumped up look – glance through bodybuilding history and you’ll see the different trends.
Kettlebell is a functional training tool that is first and foremost about improving basic athleticism of the body and real life movement quality (strength, endurance, mobility). The look, lean muscle, fat loss etc that come with kettlebell training are incidental – form follows function.
In kettlebell training, you move your body and based on the movement objective (say, a kettlebell snatch for 10 reps each side, every minute on the minute, for 5 minutes), your body develops attributes – muscle strength/size in glutes, hamstrings, back, shoulders, triceps – IN PROPORTION to what the task requires.
In bodybuilding, the size of your biceps can be functionally disproportional to the size of your lats, but visually appealing for the fashion of the day.
In kettlebell training, the size of your biceps will be exactly what it needs to be to allow you to perform swings, cleans, pullups and rows with an appropriate weight using good form. When you do compound training based on fundamental human movement patterns (squat, hinge, lunge, push, pull, carry), the muscles develop in the proportions they are used for functional movement. Which is often not the way they are developed for the preferred look with bodybuilding.
Both disciplines provide a measure of strength, mobility, endurance, appearance, muscularity and ‘the look’. Both, when done in moderation, improve your life.
But their focus is different, so you simply need to decide what’s more important to you and go from there.
Remember, you don’t have to choose strictly one or the other. It isn’t a cookie cutter prescription. You can – and I would say, must – create a mix that is unique to you, your life and your preferences.