Article

Fatigue is a complex phenomenon that is understudied. Fatigue may affect quality of life in patients with neuromuscular diseases. It is crucial for physicians to assess subjective fatigue and objective fatigue simultaneously. Questionnaires are useful in assessing the severity of subjective fatigue, and exercise protocols are useful in assessing objective physical fatigue. Validation studies need to be conducted to investigate which questionnaires are suitable for each individual neuromuscular disease. Physiologic techniques are now available for researchers to measure central and peripheral physical fatigue. It is unclear how subjective fatigue (as measured by questionnaires) correlates with objective physical fatigue (as measured by exercise protocols). The author's study in PD [18] showed that objective physical fatigue did not correlate with the symptom of fatigue that many PD patients report. This lack of correlation can be explained by the fact that the MFI measures chronic physical fatigue over weeks, whereas intermittent exercise measures acute physical fatigue over minutes. In the MFI instructions used in the author's study, subjects were told that investigators were attempting to discern «how they have been feeling lately.» The force generation administered to subjects lasts no more than a few minutes, however. It also is possible that the physical fatigue as estimated by the MFI is on a global scale that does not distinguish mental effort, the ability to sustain repetitive muscular action, or the strength of muscle contraction. These findings suggest the MFI measures different aspects of physical fatigue compared with those measured by force generation. All three measurements may be useful in future studies. It would be of interest in future studies to administer a questionnaire to measure instantaneous fatigue (with questions such as «How do you feel this instant?») and to correlate it with the physical fatigue measured by finger tapping and force generation. Studying the severity of fatigue and its underlying pathophysiology would help physicians to develop effective symptomatic treatments and improve quality of life in patients with neuromuscular diseases.

Langue : ANGLAIS