Abstract: |
Objectives: The aim of the study was to investigate the effects of different load levels on upper limb physiological tremor in the frequency band of both the 0-4.9 Hz and the 8.0-12.9 Hz. Methods: Twelve healthy volunteers performed sustained isometric shoulder extensions at 0%, 20% and 40% maximum voluntary contraction (MVC). During the contractions, mechanical recordings were made with an acceleration sensor. Tremor power was calculated for the 0-4.9 and 8.0-12.9 Hz frequency band. Results: The both TP below 5 Hz and around 10 Hz, and RMS were increased as the weight load increased. The both TP below 5 Hz and around 10 Hz, and RMS were increased as the weight load increased. In 0% MVC, there was almost no effect of muscle contraction time. On the other hand, at other weight loads, the TP increased as the muscle contraction time increased. On the relationship between RMS and muscle contraction time at each weight load, there was almost no effect of muscle contraction time. At other weight loads, there was hardly any change except for the first 10 seconds even if the muscle contraction time increased. Conclusion: 1) Total power of frequency band below 5 Hz and around 10 Hz increased as weight load increased. 2) RMS increased as weight load increased. Regarding the influence of the muscle contraction time, 3) the total power in both frequency ranges tended to increase with the passage of time except 0% MVC. 4) It was confirmed that RMS hardly changed after passage of time as compared with the total power. |