Your athletic profile begins with swimming. You know how to swim, but it has been a long time since your arms and legs have actually propelled your body through water. In other words, you have no swimming endurance.
As for cycling, you might ride a bicycle now and again, mostly noodling around the neighborhood. On occasion, you might ride a stationary bicycle at the health club while waiting for aerobics to begin or to warm up before weight lifting. As with swimming, you have no real endurance on the bike.
Finally, running. The running you do is mostly short duration, like running bases in softball, trying to avoid the outfielders. Maybe you chase a ball in racquetball. You might have even run a 5K once.
So your multisport profile for endurance sports isn't great, but you're not sitting around channel surfing either. This plan assumes you are currently active in sport three to six times per week. The specific sport isn’t as important as the fact you are active doing something. If you aren't currently active and decide to use the plan to get back into shape, be sure to consult a physician before beginning an exercise program.
One of the most common mistakes made by people just beginning to train for a triathlon, or any other endurance event, is doing too much too soon. Early enthusiasm can lead to injury or overtraining. This plan gently builds aerobic endurance in all three sports and gives specific workouts to do each week.
This 12-week plan ranges in training volume from about two hours per week to just over four hours per week. The plan goal, and your goal, is to go from a current state of no swimming, minimal cycling, and no running to completing a 450 to 500 meter swim, 11 to 15 mile bike, and about a 3 mile run, consecutively – your first triathlon.
There is a Supporting Documents section located on my main page at http://home.trainingpeaks.com/training-and-nutrition-plans/training-plans/gale-bernhardt.aspx. Please download and review these documents when you use any of my training plans. These documents give you additional information to help you get the most from your training.
This plan is also in the book "Training Plans for Multisport Athletes".