Unless you’ve been hermetically siloed within the endurance space for as long as you’ve been exercising, you’ve probably heard of muscle confusion. Popular in the vanity-oriented fitness realm, muscle confusion is the idea that muscles undergo the greatest adaptation to training when they are subjected to constantly changing stimuli, and the corresponding practice of mixing together highly varied workout types for the purpose of maximizing muscular development. Tony Horton’s blockbuster P90X program is the best-known example of a system based on this principle.

Does muscle confusion work? It depends on what you mean by “confusion” and also on what you mean by “work”? If “confusion” means varying workout types almost randomly, with no thought given to the direction they take collectively, and if “work” is defined as achieving a specific objective such as maximizing muscle strength or size, then no, muscle confusion does not work. Any serious bodybuilder or powerlifter will tell you that the best results come when workouts are varied, yes, but within fairly narrow limits, and when they are carefully sequenced so that each session (or week) builds on the preceding.

The same is true of endurance training. To develop maximum fitness for a specific race, you need to subject your body to a limited variety of stimuli repeatedly, giving the process direction by increasing the challenge level of the same stimuli as your body adapts and by giving greater and greater emphasis to the most race-specific stimuli. Injecting extra variety for variety’s sake into this process won’t help you get where you’re trying to go.

While there is something to be said for introducing little wrinkles into training for the sake of fine-tuning the race fitness of advanced and highly fit athletes, in most cases it is possible to prepare optimally for any race with a limited variety of bread-and-butter workout types. In the case of running these are easy runs, long runs, short intervals, long intervals, hill repetitions, tempo/threshold workouts, and also race-pace workouts if these aren’t already covered by the other categories (as would be the case for a runner preparing for a marathon). The rest is details: designing specific workouts and sequencing them in the best way to maximize race-specific fitness on a particular date.

I’ve never encountered a runner who includes too much variety in his or her training. A much more common problem is failure to vary one’s training stimuli enough. Just look around: In the environment where you train, are the other runners you see not all doing pretty much the same thing? How often do you pass by someone running hill repeats?

One way to add the requisite variety to your training is to follow a structured training plan. And, to be honest, that’s pretty much the only practical way for most runners who aren’t knowledgeable enough to be coaches themselves to avoid the pitfall of excessive workout monotony. Wouldn’t it be nice if there were a convenient way for athletes to select well-designed workouts to follow on an a la carte basis, so that they could vary their training stimuli in sensible ways even outside the context of a formal training plan?

Well, now there is! (You knew this was coming, didn’t you?) 80/20 Endurance Coach David Warden recently completed a Herculean effort to convert every single individual swim, bike, and run workout included in our online training plans into a discrete .FIT file that can be downloaded onto your Garmin device and taken on the go. This complete library of 80/20 workouts allows you to select the perfect training stimulus for every circumstance and receive step-by-step guidance from warm-up to cool-down. And combined with a calculator, this unique resource allows you to easily create your own 80/20 training weeks or plans.

What’s the cost, you ask? They’re free! Learn more about our new 80/20 Workout Library here.