You can build a big cardio base more quickly and effectively than by just running alone.

Cross-training in the Smart Marathon Training program is defined as any aerobic exercise that involves modes of training other than running. Under this definition, some modes of training that are important for us, such as core work and strength training, don’t qualify as cross-training because they don’t work in the aerobic zone. We’ll discuss specific training modes in my next article on Thursday.


The rationale for cross-training is simple: Your heart and cardiovascular system don’t care exactly what you do to get them in shape, so any exercise that causes an adaption response in these systems, whether in the gym or on the roads, will prepare you to some degree for a long-distance road race. Cross-training enables you to get in some big cardio workouts without putting a lot of wear and tear on the body. As a result, it can help you build a big cardio base more quickly and effectively than can be accomplished by running alone.

Here’s why: We know that running can be hard on the body because of the impact forces that it generates. But it’s not just the pounding that’s responsible for the soreness we feel after a hard workout or race. Running  is also hard on the body because of the unique nature of the movement. Most contractions involve a shortening of the muscle, as when we flex our elbow and contract our biceps. But not so with running. On landing, the knee on the supporting leg is extended and the hamstring muscles there are stretched.

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Although the hamstring muscles are not shortened at that point, they are nevertheless contracted. This contraction is called an eccentric, or negative, contraction. It’s particularly challenging to muscle tissue because it stresses the muscle in two ways simultaneously—by compression and extension. This results in a greater microtrauma to muscle tissue than usually takes place after work is done.

In weight training, eccentric contractions are good because the added stress of the negative phase of an exercise creates a greater adaptation stimulus. For example, pushing up a barbell on a bench press is not what really works the chest muscle and causes post-workout soreness; slowly lowering the barbell down to the chest does.

In running, however, this added trauma can leave muscles more susceptible to injury. As we’ve discussed, we manage that risk by limiting running to three targeted workouts per week. But this alone might not be enough to create that deep reservoir of endurance that we’ll need for a PR effort in a long distance race.

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That’s where cross-training comes in. Most cross-training options avoid the impact forces involved with running and leave you less sore and tired the following day. As a result, it’s possible to get in a long cross-training workout without having to schedule a lengthy recovery period afterward. That makes it a crucial component of the training program, allowing you to get in big workouts on days that would otherwise be filled with easy, less-productive recovery runs.

This article was adapted from the book Smart Marathon Training with the permission of VeloPress. Old-school marathon training plans ask runners to crank out 70 to 100 miles a week. It’s no wonder those who make it to the start line are running ragged. Smart Marathon Training maps out a healthier, more economical approach to training that emphasizes quality over quantity. This innovative program eliminates junk miles, paring down training to three essential runs per week and adding a dynamic strength and cross-training program to build overall fitness. Runners will train for their best performance in less time and avoid the injuries, overtraining, and burnout that come from running too much. Download a free sample and preview the book at


About The Author:

Jeff Horowitz is a certified running and triathlon coach and a personal trainer who has run more than 150 marathons across six continents. Formerly an attorney, he quit law to pursue his passion for endurance sport and now works with DC Tri; The Nations Triathlon; the nonprofit summer camp ACHIEVE Kids Triathlon; and Team Hope, a charity fund-raising training group that benefits the Hope Connections Center, a cancer-patients service organization. Learn more about Jeff at

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