For those who don't think IPSC and IDPA don't require speed, agility, and quickness, and a good overall physical fitness, you aren't analyzing the sport. Your watching the shooter not the body movements. I have seen overweight guys explode out the gate and move there feet on stages, but are tired half way through. In general, there minds tire as there body tires. I have also seen skinny guys never get tired throughout a big match, but lack speed and explosive leg strength required to be fast on field courses. Both cardio endurance and strength training improve a shooters performance. While you may not run 3 miles on a stage, the benefits to the body's efficiency can not be overlooked.
Training your muscles with fast switch exercises and core strength exercises will greatly enhance ones' performance. The trouble is, one must make up their mind how much time will be be devoted to practice or working out, and changing diapers.
For those interested in increasing your foot speed and explosiveness, read "Training for Speed, Agility, and Quickness", by Lee E. Brown and Vance A. Ferrigno.
I have greatly improved from these drills. I am faster and have recorded the times. Moving 5 yards to shooting position, springing out of a chair and sprinting 10 yards on a stage, running to squating position to shoot through a port and exploding back up, and droppng to prone and springing back up to move to another shooting position, and moving to kneeling position and getting up to another all sounds like atheletic movements to me.
Watch Dave Sevigny shoot a stage. Although he is not an average performer to use as an example, he has the hockey background to add to his game. His body movement and atheletic ability are just as impressive as his shooting abilities.
Face it, some people will find any reason not to work out, misguided or not.