Circuit training exercises are very important in most sports specific training routines as they are often performed to mirror the activity of the sport in question.
For instance, in Boxing, amateur contests usually consist of four, two minute rounds with a one minute break between rounds. This is a total of 12 minutes in length which does not sound too taxing, but please do not be fooled by how difficult this is. To replicate this, a Boxing coach will prepare possibly 4 stations for a Boxer, each station will require the athlete to perform at their absolute maximum for a two minute period as if participating in around of Boxing followed by a one minute rest. These types of training conditions the Boxer to work for a full two minutes at their maximum levels and to fully recover within the one minute's rest. By doing this over and over again a Boxer will become the perfect athlete for their chosen sport. The actual work stations used may or may not be Boxing related, with stations such as the Heavy Bag or the Boxing Pads the athlete will benefit from punching for two minutes at a time but there is a lot to be said for the stations to be non boxing related such as using a rowing machine, doing multiple repetitions of Barbell Curls or Kettlebell Swings or even something fundamentally simple such as star jumps. Whatever the activity the Cardio vascular system and different muscle groups are working hard and all the possible exercises combined help to develop the physical and mental strength of the athlete.
As eluded to above, kettlebell exercises have become very popular whatever the athletes sport when performing circuit training exercises. One of the main reasons for this is the total body workout effect of Kettlebell exercises; movements such as the Kettlebell Swing activate multiple muscle groups at once and also place heavy stress on the Cardio Vascular system. Boxing circuits in particular tend to favor the Kettlebell swing due to its reliance on the posterior chain to generate the power which is very similar to a striking movement in which a lot of the punching power a Boxer generates is from the bottom half of their body.
Circuit training exercises using kettlebells is one of the more popular methods of athletes incorporating the Kettlebells into their workouts and getting the most out of these canon ball like weights to push their physical progress onto the next level.