With all due respect to your neighbor who’s training for the Ironman Triathlon, how many days in a typical week do you swim 2 miles, bike 100 miles and then run 26 miles? You’re much more likely to, say, carry a heavy load of clothes up from the laundry room, push the lawn mower around the yard or bend and twist in order to lift an infant out of her car seat. The hot topic in health clubs is what personal trainers call functional fitness: exercise routines that train the body for its daily activities. While other workouts often isolate muscles, these focus on groups of complementary muscles, replicating the way they work together as you go through the day. They’re workouts for the real world.