In the late 20th century Soviet science verified that repetition kettlebell lifting is one of the best tools for all around physical development.
A study observed two groups of college students over a period of a few years.
A standard battery of armed forces Physical Training tests was used which included the following: Pullups, a standing broad jump, a 100 meter sprint, and a 1 k run. The control group followed the typical university physical fitness training program which was military oriented and emphasized the listed exercises. The experimental group just lifted kettlebells. No other training of any kind.
In spite of the lack of practice on the tested drills listed above, the kettlebell training group showed better scores in every one of them.