First start with a definition of a "functional Training". Simply put it is a type of training that pursue performance and health not aesthetics. Of course there is also a whole body workout (as opposite toa pin machine isolated muscles training), focus on effective movements, muscle endurance and real strength. Now, would kettlebells provide all of the above? Well a tool in of itself i.e. a kettlebell is not functional. The movements and applications you use it for is what brings function to it. Remember it. Grabbing KB and just starting "a workout" in a gym without proper plan, knowledge and understanding of what you are doing is a sure guarantee of injury. That is why you should need a trainer. KB looks simple - just a cannon ball with a handle, but the technique is not. Similar to say gymnastics apparatus. Beams, bars, horse - all look pretty simple. Would you go to a somersault on your first visit to a gymnastic hall? It takes years to master a proper technique. In KB functional training one doesn't need years, but at least twice a week attendance for at least several months under guidance of a qualified trainer is a prerequisite to an effective training when you start progressing very quickly
