It all depends on your definition of “heavy kettlebells” (or just heavy weights in general).
If you’re talking about the training, exercises, and lifestyle that strongmen or powerlifters do, then no, it’s terrible for the body.
Many of these athletes are literally eating as much as they can to get as big as possible and to lift as much weight as possible. They are doing whatever it takes to be the best. As a result, they are putting themselves at risk for a multitude of health issues, like strain on the cardiovascular system, and destroying the joints.
However, “heavy lifting” is a subjective term.
Lifting weights in general, with reasonably heavy weights and good form – like I teach in my KB / BW Hybrid Training 2.0 course! – can be highly beneficial to the body. It contributes to increased muscle mass (which has been shown to have a positive impact on mortality rates) as well as increasing bone density (which is huge in counteracting the effects of aging and arthritis).
To learn how to lift kettlebells properly and with good form, so that you can get all of the benefits and none of the risks, check out KB / BW Hybrid Training 2.0 at the link below:
Master of Science, Human Movement
SFG-Certified Kettlebell Instructor
Owner, FVT Personal Training (gym in Sacramento, CA)
Owner, KettlebellBasics.net (online / worldwide)