Impairment of voluntary control of finger motion following stroke: Role of inappropriate muscle coactivation

• Published in: Muscle & nerve Vol. 24; no. 5; pp. 673 - 681
• Main Authors: Kamper, D.G., Rymer, W.Z.
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 01.05.2001; Wiley
• Subjects: Aged; Biological and medical sciences; coactivation; Electromyography; Female; fingers; Fingers - innervation; Fingers - physiopathology; Humans; Isometric Contraction - physiology; Joints - innervation; Joints - physiopathology; Male; Medical sciences; Middle Aged; Movement - physiology; Muscle Contraction - physiology; Muscle, Skeletal - innervation; Muscle, Skeletal - physiopathology; Neurology; Receptor Cross-Talk - physiology; reciprocal inhibition; stroke; Stroke - physiopathology; Vascular diseases and vascular malformations of the nervous system; voluntary control; Human; Hemiparesis; Nervous system diseases; Stroke; Motor system disorder; Voluntary control; Finger; Cardiovascular disease; Isometric muscular contraction; Striated muscle; Joint; Muscle coactivation; Cerebral disorder; Osteoarticular system; Vascular disease; Central nervous system disease; Extensor muscle; Flexor muscle; Hemiplegia; Electromyography; Neurological disorder; Cerebrovascular disease
• ISSN: 0148-639X; 1097-4598
• DOI: 10.1002/mus.1054

Subjects with chronic hemiplegia following stroke attempted to perform voluntary isometric, isokinetic, and free contractions of the extensor muscles of the metacarpophalangeal (MCP) joints. We recorded torque, metacarpophalangeal joint angle and velocity, and electromyographic (EMG) activity of the extrinsic extensors and flexors and the first dorsal interosseous (FDI). We found that voluntary MCP joint extension in hemiparetic subjects was greatly impaired in comparison with control subjects: only two of the 11 stroke subjects were able to generate even 0.21 N‐m of isometric extension torque, only two could produce positive finger extension with no load, and none could develop an isokinetic concentric extension. Deficits seemed to result from a combination of coactivation of the finger flexor and extensor muscles and decreased voluntary excitation of the extensors, as normalized flexor and FDI EMG activity were greater for stroke than for control subjects (P < 0.001), but normalized extensor activity was reduced (P < 0.001). © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 673–681, 2001