The Impacts of Central Fatigue on the Polyphasic Nature of Tapping Performance

Abstract

Objective: As a non-specific symptom muscle fatigue mostly accompanies neuromuscular diseases and also occurs frequently in healthy individuals. Fatigue phenomenon is considered to be multidimensional symptom. There have been still discussions on the origin whether it depends primarily on the intrinsic properties of muscle itself (peripheral mechanisms) or the nervous system that controls muscle (central mechanisms). This study aimed to investigate the effects of central fatigue on the performance of maximal voluntary repetitive movement and discusses the specificity of finger tapping task test as a simple diagnostic tool for fatigue. Methods: For this purpose, 27 healthy, male, right-handed volunteer performed the 20-s of finger tapping task test for four times. The one was for control and the other three were performed right after induction of three different central fatigue models. Temporal behavior of tapping performances were evaluated based on inter-tap intervals and the statistical comparison were made by regression analysis. Results: The results showed that the partial evaluation of the task in time domain instead of complete test period yielded with statistically significant differences between control and fatigue models (p<0.001) and even in between the fatigue models. Conclusion: Approximately the first 5-s of a finger tapping task consists of both motor learning processes and dynamics of energy consumption from anaerobic sources. However, it reflects dominantly the central components of fatigue. We may conclude that the temporal behavior of tapping performance following the induction of specific fatigue model may help making further discrimination for the origin of fatigue.