Cross training on new plans | 80/20 Endurance

Cross training on new plans

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    The previous plan had workouts marked as do XYZ or cross train.
    The new 2021 plans don’t have this however I still wish to do so, which workouts are best to swap ?

    David Warden


    Thanks for being one of our athletes. We address this in our updated documentation in Understanding Your 8020 Run Plan, the relevant section included below for your convenience.

    Although there are no formally scheduled cross-training sessions in the runs plans, you have a standing option to replace any Recovery Run or Foundation Run with a nonimpact cardio alternative of equal duration and intensity. You will see periodic reminders of this sprinkled throughout each plan.

    So, when should you cross-train and when should you run? There are two competing, but equally valid, truths to consider when deciding whether to run or to cross-train. On the one hand, the more you run, the more you’ll improve as a runner. The principle of specificity teaches us that if you run instead of cross-training each time you see a Recovery Run or Foundation run on your schedule, your running performance will increase more than if you do the opposite. On the other hand, above a certain level, the more you run, the more likely it is that you will develop an impact-related overuse injury such as runner’s knee. So, if you’re injury prone or concerned about injury, you may be better off doing some or all of your Recovery Runs and Foundation Runs in a nonimpact cardio exercise modality such as bicycling.

    There are two basic approaches to replacing runs with cross-training: the programmatic approach and the as-needed approach. In the programmatic approach, you replace certain runs with cross-training sessions routinely. For example, you might replace your first Foundation Run of each week with an elliptical workout. In the as-needed approach, you replace runs with cross-training only when soreness or fatigue from prior running makes running again seem inadvisable. Note that these two approaches are not mutually exclusive, and indeed you should cross-train instead of running anytime it seems risky to run, regardless of whether you also practice the programmatic approach. Finding the right balance for you may require some trial and error (See the section The Importance of Listening to Your Body below).

    The best cross-training activities are those that are most similar to running without the impact element. Pool running, antigravity treadmill running, indoor and outdoor cycling, elliptical running, outdoor elliptical biking, steep uphill treadmill walking, indoor and outdoor cross-country skiing, inline skating, and steep uphill treadmill walking have all been used successfully. Strength training is a completely different sort of cross-training that we strongly recommend but as a complement to aerobic cross-training rather than a substitute for it. See Incorporating Strength Training to Your Plan for ideas on how to incorporate strength training into your plan.

    Note that effective 80/20 training requires that you spend 80 percent of your combined aerobic training, encompassing running and cross-training, at low intensity. In the case of our 80/20 Run plans, this means all of your cross-training sessions need to be done in Zones 1 and 2.



    Hey guys – I’m in week 4 of the marathon plan and loving it. One follow-up to this topic: Currently, I replace 2 runs with sessions on the slide-board (I might consider the bike when it’s bit warmer). However, I think I might be able to put more miles in. I’ve been doing the “conservative” approach outlined in the book due to my age (early 50s) and previous injury history when mileage goes up. But my recovery runs are much easier than they were previously (owed in no small part to a bunionectomy).

    So the question: What advice do you have on how can I test replacing cross training with recovery runs safely?

    David Warden


    I propose you start by first replacing your cross-training not with running, but with strength training. That will both improve your running and reduce your injury frequency. That’s probably the best answer for a full season: don’t increase the miles, add strength training. Studies show that endurance athlete improve when they replace their endurance training with strength training. Meaning, not only adding strength training to your existing miles, but replacing up to 1/3 of your running with strength training.

    If you really want to add more miles, I recommend introducing the shorter of the two run sessions with the scheduled run for 6 weeks. If that works without injury, then add the second run workout.




    Since I already do 2 strength trainings a week, I’ll add 1 more. And later switch out 1 cross for 6 weeks. I see what you’re saying about the strength training – I started doing them back in January and they’ve made a huge difference already.

    Thanks, David!

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