The concept of different sports using different muscle groups seems like an obvious tenet, yet most people do not think about exercising to improve their performance in a particular sport. They are only concerned with practicing the sport. Of course, it is logical to assume that extensive practice of a particular sport will train the needed muscle groups to be in great shape. However, the reverse is not always true. For instance, just because you exercise the muscles used by playing football does not mean you will be a good football player, but it is a start.
Some of the muscle groups that are called into play when becoming proficient at a particular sport are fairly obvious, but others certainly take a little more thought to identify the muscle groups. At the professional level, an athlete will work on the major muscle groups, but maintaining balance in the entire body through recognition of the lesser muscles is important as well. So, while many sports focus on one aspect of the body, overall balance is emphasized as well.