Co-activation of upper limb muscles during reaching in post-stroke subjects: An analysis of the contralesional and ipsilesional limbs

Abstract

The purpose of this study was to analyze the change in antagonist co-activation ratio of upper-limb muscle pairs, during the reaching movement, of both ipsilesional and contralesional limbs of post-stroke subjects. Nine healthy and nine post-stroke subjects were instructed to reach and grasp a target, placed in the sagittal and scapular planes of movement. Surface EMG was recorded from postural control and movement related muscles. Reaching movement was divided in two sub-phases, according to proximal postural control versus movement control demands, during which antagonist co-activation ratios were calculated for the muscle pairs LD/PM, PD/AD, TRIlat/BB and TRIlat/BR. Post-stroke's ipsilesional limb presented lower co-activation in muscles with an important role in postural control (LD/PM), comparing to the healthy subjects during the first sub-phase, when the movement was performed in the sagittal plane (p<0.05). Conversely, the post-stroke's contralesional limb showed in general an increased co-activation ratio in muscles related to movement control, comparing to the healthy subjects. Our findings demonstrate that, in post-stroke subjects, the reaching movement performed with the ipsilesional upper limb seems to show co-activation impairments in muscle pairs associated to postural control, whereas the contralesional upper limb seems to have signs of impairment of muscle pairs related to movement.

The Use of Functional Electrical Stimulation on the Upper Limb and Interscapular Muscles of Patients with Stroke for the Improvement of Reaching Movements: A Feasibility Study

“…The mean time since the stroke episode was 6.18 ± 3.12 years. Regarding the type of stroke, 38.10% (8) were ischemic and 61.90% (13) were hemorrhagic. The mean score of participants on the motor function domain of the UL-FMA was 26.87 out of 66 points (SD 10.6), with 72.25 out of 126 points (SD 20.41) on the total score of the UL-FMA (including the sensory, passive ROM, and pain subscales).…”

“…Regarding the UL muscles involved in reaching movements, a deficit in muscle control and activation has been observed (5, 12, 13). The synergistic contraction of the shoulder flexor and extensor muscles during reach becomes deteriorated due to muscle weakness and; therefore, the resulting movement is deficient (14).…”

Flexion synergy overshadows flexor spasticity during reaching in chronic moderate to severe hemiparetic stroke

“…Other investigators have reported that increased agonist/antagonist co-activation of biceps/triceps about the elbow joint impedes reaching movement however did not measure biceps co-activation with deltoid (Silva et al, 2014). Substantial co-activation at the elbow joint was observed in the present study however it began prior to the onset of elbow extension movement during the lifting portion of the task.…”

Spastic co-contraction, rather that spasticity, is associated with impaired active function in adults with acquired brain injury: A pilot study

“…It has been suggested that spastic co-contraction may contribute to limitations in active movement (4). However, to date, the impact of this disabling form of muscle overactivity on motor function in brain-injured adults has been only sparsely and indirectly studied (5). In addition, most treatments aimed at improving upper limb function, such as rehabilitation or botulinum toxin, focus on spasticity as the primary outcome in clinical practice (6).…”