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Muscle Confusion: An Undulating Path to Strength Gains 

Learn the secret to overcoming fitness plateaus with Groupon's guide to muscle confusion.

Study muscle growth in any depth and you might easily reach this conclusion: muscles are kind of lazy. When you work out, your muscles go through an adaption period, growing so that they can handle the extra stress being put on them. But when they’re exposed to the same amount of stress or intensity all the time, they get used to it and promptly stop making gains. To overcome this plateau and destroy muscles’ attitude of smug complacency, trainers might prescribe a program of muscle confusion. That means strategically mixing up the order of workouts, the amount of resistance, length of rest periods, intensity, or other factors so no muscle group gets too familiar with the move.

Charles Poliquin, an athletic trainer who has designed workouts for 17 Olympic sports and for professional sports teams, is most often credited with introducing the concept physiologically known as undulating or nonlinear periodization in 1988. “Nonlinear” refers to the constant fluctuation in workout intensity (as opposed to progressing methodically through higher weight loads, for instance), and “periodization” refers to a specific plan for cycling through workout changes in order to give all the muscles enough attention.

Some studies have found muscle confusion, as it’s now commonly called, to be more effective in promoting long-term fitness and in boosting performance levels, and popular workout systems such as P90X and Insanity plan their intense regimens according to these principles. But if you prefer the comfort of a predictable routine, other experts are on hand to back you up, noting that if you’re focusing on a specific muscle group it may take weeks to get all you can out of a given move.