By Steve Edwards

In today's installment of customizing P90X®, we'll address endurance athletes. As you might have surmised, doing the Back & Biceps workout isn't going to improve your marathon time. And no week of P90X leaves you feeling ready to take on an Ironman triathlon over the weekend. So what's the deal? The question we most often get is whether the X is going to improve your finish times, or should you skip it in favor of more sports-specific training?

The short answer is that P90X can improve every aspect of your endurance sport. However, it's important to ask yourself a few questions before you begin, because if you go about it the wrong way you can hurt your performance.

1: What are my goals in my chosen sport?

This question is vital because some of you likely do endurance events only to improve your fitness. When this is the case, you're best off doing P90X the way it's designed and suspending your sports-specific training.

Because you probably already have a decent aerobic base, you should respond quickly to the rigors of P90X. And while you'll be sore and tired in the short term, and lose some of your endurance fitness, you'll also make rapid body composition changes. These changes will help you should you choose to get back into your sport. However, with fitness as your measuring stick, doing rounds of P90X between rounds of endurance sports training will help you keep your fitness level high.

Things get trickier when sports performance is important. If PRs (personal records) are your ultimate goal, you'll want to consider how P90X can help you make it happen.

In the strictest sense, you should do P90X in the off-season. Most endurance athletes would benefit from a period each year where they stopped (or mostly stopped) their sports-specific training and did a good fitness program. This is especially true if you need to lose weight, or you have weakness because it's likely your fitness results have hit a plateau after a long season where you did the same things over and over.

2: Which version of P90X should I do?

Your next decision is which schedule of P90X to do: Lean, Classic, Doubles, or some hybrid version. Here are some scenarios to consider.

If you're an overweight person who has a high percentage of body fat, choose the Classic schedule, because resistance training and gaining muscle are the quickest way to slim down and change your body composition to more muscle and less fat, which will help you more than any other type of training.

If you're fit with a lot of muscle mass, choose the Lean schedule. You'll benefit from strength training and explosive cardio (which put different stress loads on the body than running, riding, swimming, etc.) but you won't add more mass, which is good because strength-to-weight ratio is paramount in endurance sports.

Someone in between might choose a hybrid schedule, the simplest of which would be a program that begins with the Classic schedule and transitions to the Lean schedule.

The last example could also be used by anyone who's closer to their race program and still wants to try some outside training. In these cases, you could start with the Classic P90X schedule for a phase or so (time will dictate this), then transition to the Lean schedule for a phase, and then perhaps transition to a customized schedule to accommodate your sports-specific training needs.

In the off-season, I wouldn't recommend the Doubles schedule, which doubles up workouts, because the off-season is when you should make body composition changes, and also when you should rest. Endurance training is intense once you begin racing; when you begin to add miles into your program again, you want to be rested.

3: What if it's close to my race season?

Most race seasons are long, taking up around nine months of the year on average. Since no one—even a professional—can peak for the entire season, you should set up your schedule with early-season objectives you train through and late-season objectives where you want to set your PRs. Remember, the actual season doesn't matter—only your schedule does. You should choose to peak around times when you can focus and devote yourself to training, not an arbitrary date on the calendar.

Early season (your early season) is a time when you should be combining sports-specific training along with off-season training. These transition seasons are when you'll want to incorporate a Doubles-style training schedule.

As an athlete, your Doubles schedule should have sports-specific work. This means you'll want to alter the P90X schedule of your choice to incorporate your sport. As an endurance athlete, the general place you'll add this training is the cardio slot on the calendar. Remember that one of the two daily workouts is always an easy cardio workout, which is a perfect slot to do your early-season aerobic conditioning.

As we get closer to the actual racing season, there are many other considerations. We'll take these on per sport. Next time we'll look at scheduling P90X with running. Then we'll focus on triathlons.