If I could clone myself a few times for the sake of taking different paths in life, I would definitely dedicate one of my clones to the pursuit of sports science. This being impossible with current technology, I choose instead to live vicariously through the individual sports scientists who are tackling the questions I would be most interested in tackling if I had my own lab.

One such question (or line of questioning, more accurately) is this: If you could do only one thing right in your training as an endurance athlete, what should it be? In other words, what is the single most beneficial training practice you could employ as an endurance athlete seeking improved performance? And if you were already doing this one thing, what then is the next most impactful method you could incorporate?

If we were to pursue this line of questioning all the way through to the end, we would end up with a sort of hierarchy of endurance training needs. How useful that would be! Well, guess what? This hierarchy already exists, created by one of my very favorite sports scientists, Stephen Seiler, who drew upon his encyclopedic knowledge of research on endurance training practices to perform the exercise I just described. With a nod to Abraham Maslow’s famous hierarchy of psychological needs, Seiler’s Hierarchy of Endurance Training Needs ranks eight fundamental training practices in order of proven impact. If there’s a more helpful tool for understanding the big picture of endurance training, I haven’t seen it. So, let’s go through the hierarchy (see Seiler’s own graphical summary at the end of this post):

  1. Total Frequency/Volume of Training

According to Seiler, the single most beneficial thing you can do to improve your performance in endurance racing is to train a lot. The fine print is that in training a lot, you must be sure not to train too much, and you can train more without training too much if you train at low intensity, so what Seiler really means here is that the single most beneficial thing you can do to improve your performance in endurance racing is do a lot of low-intensity training.

  1. High-Intensity Training

 Although doing a lot of training exclusively at low intensity will make you fitter than doing a small amount of any other kind of training, you will get fitter still if you combine a little high-intensity training with a lot of low-intensity training. Seiler rates this fact as “well established” in the scientific literature.

  1. Training Intensity Distribution

Seiler made a name for himself by discovering the 80/20 Rule of endurance training, which posits that endurance athletes improve the most when they do roughly 80 percent of their training at low intensity and the remaining 20 percent (give or take) at moderate to high intensity. So, the next most impactful thing you can do in your endurance training—if you’re already doing a lot of low-intensity training and a little high-intensity training—is to fine-tune the balance of intensities to bring your training in line with the 80/20 Rule.

Let me add here that applying the 80/20 Rule is usually the first change that I make to the training of the athletes I coach. The reason is that the average recreational endurance athlete does close to 50 percent of his or her training at moderate intensity—way too much. Training more won’t help an athlete who is caught in the moderate-intensity rut because it only exacerbates an existing problem. There is much more to be gained from redistributing the training he or she is already doing and then taking advantage of the reduced stress and fatigue levels resulting from this shift to train more.

  1. General Periodization Details (Annual)

 Periodization refers to the practice of evolving one’s training over the course of the year in specific ways intended to cause fitness to continually increase. Seiler rates this practice as “likely overrated.” By this I don’t think he means that training shouldn’t evolve over the course of the year but rather that the details don’t matter much. If that’s the case, then I agree wholeheartedly. What does matter is that 1) the overall training workload (which is a function of both the volume and the intensity of training) increase and 2) your most challenging race-specific workouts come later on, when your fitness is near peak levels and it’s getting close to time to race. But the relevant research has shown that within these broad parameters, different periodization practices yield similar results. In other words, where periodization is concerned, there’s more than one way to skin a cat.

  1. Sports-Specific and Micro-Periodization Schemes

 According to Seiler, the particular ways in which endurance athletes chose to sequence workouts from day to day and week to week has a “likely modest” effect on fitness. In other words, it doesn’t matter too much whether you schedule recovery weeks every third week or every fourth week. Of course, it’s vitally important that you balance hard work and rest/recovery in such a way that your body neither accumulates fatigue over extended periods nor detrains between challenging training stimuli, but as with macro-periodization, there’s more than one way to achieve this balance.

  1. Training-Stimuli Enhancement

 “Training stimuli enhancement” refers to practices such as training at high altitude and training in a glycogen depleted state. Seiler believes that such things are worth doing but that the effects are “individual and condition specific.”

  1. Pacing Training

Fitness is not the only determinant of race performance. To get the most benefit from any level of fitness in competition, an athlete must pace himself or herself effectively, and this objective is aided by practicing pacing in training, which may also serve to stimulate pace-specific fitness adaptations. Seiler rates this practice as “potentially decisive if everything else is done right.”

  1. Training Taper

Although your fitness level won’t change much in the last week or two before a race, no matter what you do, what you do in the last week or two before a race can have a big impact on how you perform nevertheless. Tapering is the art (Stephen Seiler might say science) of altering your training prior to competition to ensure that you’re rested—but not too rested—and physiologically primed for a maximal effort. Science has shown clearly, for example, that endurance athletes race better when they include high-intensity work in their taper than when they do everything at low intensity. Seiler rates tapering as “potentially decisive if you have one isolated competition. . . and everything else is done right.”

Learn more here: https://www.researchgate.net/profile/Stephen_Seiler/publication/310725768_Seiler%27s_Hierarchy_of_Endurance_Training_Needs/links/583590c208ae004f74cc51f5/Seilers-Hierarchy-of-Endurance-Training-Needs.pdf