Temporal modulations of agonist and antagonist muscle activities accompanying improved performance of ballistic movements.

Full Abstract

Although many studies have examined performance improvements of ballistic movement through practice, it is still unclear how performance advances while maintaining maximum velocity, and how the accompanying triphasic electromyographic (EMG) activity is modified. The present study focused on the changes in triphasic EMG activity, i.e., the first agonist burst (AG1), the second agonist burst (AG2), and the antagonist burst (ANT), that accompanied decreases in movement time and error. Twelve healthy volunteers performed 100 ballistic wrist flexion movements in ten 10-trial sessions under the instruction to "maintain maximum velocity throughout the experiment and to stop the limb at the target as fast and accurately as possible". Kinematic parameters (position and velocity) and triphasic EMG activities from the agonist (flexor carpi radialis) and antagonist (extensor carpi radialis) muscles were recorded. Comparison of the results obtained from the first and the last 10 trials, revealed that movement time, movement error, and variability of amplitudes reduced with practice, and that maximum velocity and time to maximum velocity remained constant. EMG activities showed that AG1 and AG2 durations were reduced, whereas ANT duration did not change. Additionally, ANT and AG2 latencies were reduced. Integrated EMG of AG1 was significantly reduced as well. Analysis of the alpha angle (an index of the rate of recruitment of the motoneurons) showed that there was no change in either AG1 or AG2. Correlation analysis of alpha angles between these two bursts further revealed that the close relationship of AG1 and AG2 was kept constant through practice. These findings led to the conclusion that performance improvement in ballistic movement is mainly due to the temporal modulations of agonist and antagonist muscle activities when maximum velocity is kept constant. Presumably, a specific strategy is consistently applied during practice.

Author information

Author/s: Liang, Nan (N); Yamashita, Takamasa (T); Ni, Zhen (Z); Takahashi, Makoto (M); Murakami, Tsuneji (T); Yahagi, Susumu (S); Kasai, Tatsuya (T);

Affiliation: Department of Rehabilitation of Locomotor System Dysfunction, Graduate School of Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan.

Journal and publication information

Publication Type: Journal Article

Journal: Human movement science (Hum Mov Sci), published in Netherlands. (Language: eng)

Reference: 2008-Feb; vol 27 (issue 1) : pp 12-28

Dates: Created 2008/01/24; Completed 2008/04/14;

PMID: 17936390, status: MEDLINE (last retrieval date: 2/18/2009, IMS Date: )

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

External Links for this article
(including full text providers, if available):

Click Electronic Full-text Provider Links to see options for finding the electronic full text links to this article. Note there may be a subscription or fee required for access to the full text. See our FAQ for information on finding FREE full text articles.

This article may also be located in paper journal collections available in many libraries. Use the Journal and Publication Information above to find the full article.