Effects of upper limb immobilization on isometric muscle strength, movement time, and triphasic electromyographic characteristics.

The effects of short-term immobilization on isometric muscle strength, movement time, and triphasic integrated electromyographic characteristics were assessed during a simple ballistic elbow flexion and extension movement. The nondominant upper limbs in six subjects (two female, four male) were immobilized in a plaster cast for 14 days. Testing consisted of isometric muscle strength output of elbow flexors and extensors; movement time; and IEMG output of the agonist, antagonist, and second agonist contractions during the ballistic movements. An analysis of variance revealed a decrease in flexor strength of the casted limb (p less than .05). Movement time was not significantly slowed. Antagonist IEMG amplitude was decreased (p less than .01) during flexion, and agonist IEMG amplitude (p less than .05) and antagonist IEMG amplitude (p less than .05) were diminished during extension of the casted limb. In conclusion, short-term upper limb immobilization affects primarily elbow flexion strength and some IEMG characteristics during a ballistic forearm movement, suggesting an influence on the neuromuscular aspects of the affected muscles.