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Deficits underlying handgrip performance in mildly affected chronic stroke persons

ABSTRACT Background Knowledge of the deficits underlying handgrip performance is fundamental for the development of targeted interventions. Objectives The purpose of this study was to evaluate maximal handgrip strength, fatigue resistance, grip work, and muscle fatigue in mildly affected stroke persons. Methods We conducted a prospective observational study. A total of 20 individuals after a first unilateral ischemic/hemorrhagic chronic stroke (months poststroke: mean 33.64 ± 19.60), mildly affected according to functional score (FIM: 112.71 ± 16.14) and with arm motor impairment (upper-extremity Fugl-Meyer score: mean 57.07 ± 7.82 on the contralesional side); and 20 sex and age-matched controls were included. The outcomes assessed were maximal handgrip strength evaluated through maximal voluntary contraction, fatigue resistance defined as the seconds during which grip strength dropped to 50% of its maximum and gripwork, which was calculated using the equation grip work = maximal grip strength * 0.75 * fatigue resistance. Muscle fatigue was assessed using surface electromyography during a sustained contraction over 50% of maximal voluntary contraction. Results Persons with stroke demonstrated significantly reduced handgrip performance regarding maximal handgrip strength, resistance to fatigue, grip work, and muscle fatigue for the contralesional hand. In addition, a reduced grip resistance and muscle fatigue was shown for the ipsilesional hand compared with controls. We found no effect of the hemispheric side of the lesion on the grip performance measures assessed. Conclusions Our findings provide evidence that handgrip performance remain impaired after 6 months after stroke, and may serve as a target for interventions to improve these abilities after stroke.