Fatigue & Health

In the FATIGUE & PERFORMANCE section, we showed you how much exercise-related fatigue is a complicated symptom. If you have read the articles and watched the videos in that section, we hope this seems clear to you now.

Chronic fatigue is even more complicated (see figure B in ABOUT FATIGUE). It is defined as a feeling of exhaustion that interferes with a person’s normal functioning (professional activity, social relationships, tasks of day-to-day living) and that does not improve with sleep or rest. Chronic fatigue is the #1 symptom of many illnesses. It also affects other people, especially the elderly. It is a real public health problem, and worse, this symptom is often neglected by doctors, for lack of effective treatment, because the causes of chronic fatigue are not known. This situation has terrible consequences for the population as a whole, in terms of quality of life, but also regarding productivity and absenteeism.

The indirect effects of chronic fatigue are even worse. This is perfectly well described by the illustration below representing the vicious circle of fatigue. A tired person will tend to opt for sedentary behavior (poor dog!) which will lead to physical deconditioning and muscle atrophy (= drop in mass). Which in turn necessarily further increases the level of fatigue.

No effective treatment then? This is not entirely true. Although it seems counter-intuitive, it turns out that physical activity is a good remedy for fatigue. We don't really know why (see some hypotheses here) but it works!

One of the explanations given in the article is as follows: when we have a low tolerance of physical fatigue, each effort (climbing the stairs, vacuuming, shopping) will cost us more energy, and it will take longer to recover. This brings on the feeling that everything is more and more difficult. As a result, as shown in the figure below, we will choose to limit our efforts as much as possible so as not to exceed the tolerable fatigue threshold. As thus the amount of activity carried out each day will decrease, resulting in muscular deconditioning as represented in the vicious circle of fatigue described above!