Training Concepts - Part 1 (stress/adaptation)

author : JorgeM
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Article explaining simple training concepts important for any endurance program

Any time coaches or athletes talk about endurance training and the seemingly infinite ways to structure a training program, frequently the conversation focuses on the various methods or protocols that can be used to achieve specific athletic goals (from completing your 1st 10K to finishing an Ironman). In these conversations, coaches usually ignore or pay lip service to the different responses and adaptations our bodies go through during endurance training.

For many athletes this topic is irrelevant, as their goal is not to understand the specifics of their training. They just want to know "when to do what" to achieve their goals. Other athletes do want to understand the specifics of their programs so they can maximize their gains in the future. For coaches, it is imperative to have a basic understanding of training concepts and physiology in order to develop optimal programs for each athlete.

The series will focus on those athletes and coaches who want to understand these concepts. I’ll go through different training concepts in a simple way, explain their importance for endurance training and how these simple ideas can be applied to your training/coaching; it will be my attempt at blending evidence-based concepts with the ‘art’ of coaching (that is, understanding individual needs).


When we perform endurance training, we produce a number of different adaptations in our body. Below there are just some of those physiological changes (in no particular order):
  • Increase in muscle capillarization
  • Increase in mitochondria density
  • Improve in fuel oxidation
  • Improve on max aerobic capacity
  • Improve in muscle fiber fatigue resistance
  • Improve buffering and utilization of acid
  • Increase muscle glycogen storage
  • Increase plasma volume

For now, the type of adaptations that occur are not relevant; the point I am trying to illustrate is that endurance training produces a series of changes in your body that ultimately will allow you to go faster, longer or both. This is related to the stress/strain/adaptation response.

Adaptations and Training Concepts

Traditional training concepts have evolved as the result of experimentation (trial and error). That is, athletes were exposed to different kind of stresses to see the effects this had on them. In 1936, Hans Selye performed a series of experiments on mice and discovered that different “stressors” create different levels of strain, which can lead to different physiological responses. Eventually this lead to a greater understanding on how a stress produces a response in our body.

Training is considered a stressor, and how much and how hard you do it will produce different responses. In general it follows the same pattern: the stress is the activity, the strain is how much of it we do (duration/intensity), and adaptation is our body’s response to that. This is also known as the overload/super-compensation concept. However if we do more than what our body can handle, then it won't be able to cope with the strain, which can lead to excessive fatigue or injury.

Let's take a short run as an example. The stress will be running, the strain will be how far and how hard you run, and the adaptation will be the result of how your body adapts:

  • Positive - If the total strain matches with what your body can currently handle (current fitness level), the stimulus is such that it disturbs your body’s homeostasis enough that once it body recovers, it will produce positive adaptations. i.e. the next time the same run will seem/feel a bit easier.
  • Unchanged – if the total strain is not enough to disturb your body’s homeostasis forcing any adaptations (less of what your body can handle) then the changes for the next session might be non-existent.
  • Negative – if the total strain exceeds of what your body can currently handle (doing too much) greatly disturbing your body’s homeostasis, then your body will either take too long recover/adapt; this can lead to excessive fatigue and injuries.

Over time, if you manage your training load effectively (something I’ll in the next article), then your body will constantly be in the adaptation stage allowing you improve and use your training time more effectively. With a proper program, what today was challenging tomorrow will be less challenging. If today you can only go so far, tomorrow you’ll be able to go a bit farther, also know as super-compensation.

Unfortunately, simple concepts such as the stress/adaptation and training load management are often misunderstand and/or incorrectly applied. That’s why so many athletes, in particular those newer to endurance training, end up developing injuries or other setbacks. As you read over the next articles, hopefully you’ll learn how to avoid this.

For now, the take-home message is: training is nothing more than a stress/strain/adaptation program in which we seek to do enough to force our body to adapt and become faster and fitter, but not so much that our body can’t adapt, and it breaks down and makes our program inconsistent and unpleasant.

In Part 2 I will explain Training Load concept.

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date: May 10, 2011