Altered neuromuscular activity and postural stability during standing balance tasks in persons with non-specific neck pain

OBJECTIVES

To compare neck, trunk, and lower extremity muscle activity in standing in persons with neck pain (NP) to healthy controls and determine associations with postural sway.

METHODS

Participants included 25 persons with NP and 25 controls. Surface electromyography was recorded bilaterally from neck (sternocleidomastoid, SCM; splenius capitis, SC; upper trapezius, UT), trunk (erector spinae, ES), and lower extremity (rectus femoris, RF; biceps femoris, BF; tibialis anterior, TA; medial gastrocnemius, GN) muscles. Postural sway was measured using a force platform in narrow stance with eyes open/closed, on firm/soft surfaces.

RESULTS

Compared to controls, the NP group demonstrated higher activity in all muscles, except UT and had higher amplitude ratios for neck muscles (SCM, SC) for all tasks (p < .05). No between-group difference was found in amplitude ratios for lower extremity muscles, except for GN. Lower extremity activity was moderately correlated with larger postural sway for both groups (r = 0.41-0.66, p < .05). There were no correlations between sway and neck and trunk muscle activity (p > .05).

CONCLUSION

Increased muscle activity with NP is associated with increased postural sway. Both groups used similar postural control strategies, but the increased neck activity in the NP group is likely related to the NP disorder rather than postural instability.

Malondialdehyde as a Useful Biomarker of Low Hand Grip Strength in Community-Dwelling Stroke Patients

The assessment of muscle strength by hand grip strength (HGS) is used to evaluate muscle weakness and wasting among stroke patients. This study aimed to investigate the association of oxidative stress/oxidative damage and inflammatory biomarkers with muscle strength and wasting, as evaluated by HGS, among community-dwelling post-stroke patients. The HGS of both paretic and non-paretic limbs was negatively associated with modified Rankin scale (mRS) values. The serum levels of catalase activity and malondialdehyde (MDA), and plasma tumor necrosis factor (TNF)-α levels were significantly increased in post-stroke patients compared with non-stroke controls. Further analysis highlighted that hydrogen peroxide was positively correlated with HGS in the paretic limbs. Interestingly, an elevated MDA level, excluding advanced age and high mRS, increased the risk of low HGS in the non-paretic limbs of stroke patients. This study suggests that there is a detrimental association between MDA and muscle strength and early muscle wasting among post-stroke patients. Hence, MDA is a potentially useful biomarker of muscle weakness and wasting in post-stroke patients living in the community.

Reach-to-grasp training in individuals with chronic stroke augmented by low-frequency repetitive transcranial magnetic stimulation

OBJECTIVE

The present study investigated the immediate effects of low frequency repetitive transcranial magnetic stimulation (LF-rTMS) combined with reach-to-grasp (RTG) training of the paretic hand in individuals with chronic stroke.

MATERIAL AND METHOD

Fourteen participants were randomly assigned to receive LF-rTMS or sham stimulation conditions. All participants underwent RTG training after the stimulation. Corticospinal excitability (CE) of the non-lesioned hemisphere, the total time of the wolf motor function test (WMFT) for dexterity tasks, maximum aperture, and movement time of RTG actions were evaluated at baseline, after the stimulation, and after RTG training.

RESULTS

Significant differences between interaction (group x time) were found in the total time of WMFT The CE of non-lesioned hemisphere diminished after LF-rTMS and showed moderate correlation with the reduction in time of RTG actions after the stimulation. The total time of WMFT and RTG actions reduced after motor training only in the LF-rTMS group. No change was observed in maximum aperture in either group.

CONCLUSION

The application of LF-rTMS combined with RTG training enhanced the training effect as evidenced by faster movement for the dexterity tasks of the paretic hand than RTG training alone. The findings suggested the benefit of LF-rTMS for enhancing the training effects in stroke rehabilitation.