The investigators hypothesized that bilateral handgrip force training would result in significant improvements in paretic hand, arm movements and daily functional performances. In order to investigate whether the improvement of paretic hand could facilitate the motor recovery of paretic arm and functional performances, the investigators also hypothesized that motor recovery and functional performances improvements of paretic arm and hand have strongly correlation.

Objective: To investigate the training effects of interlimb force coupling training on paretic hand and upper extremity outcomes in patients with chronic stroke; to analyze the relationship between motor recovery of paretic hand, arm and functional abilities.

Design: A double-blind randomized controlled trial with outcome assessment at baseline and after 4 weeks intervention.

Setting: Department of physical medicine and rehabilitation in Taipei Veterans General Hospital.

Participants: Thirty-three subjects (mean age = 55.1 ± 10.5 y/o) with chronic stroke were recruited and randomized assigned to training (n=16) and control group (n=17).

Interventions: Interlimb force coupling training task included different gripforce generation on the both hands.

Main Outcome Measures: Barthel Index (BI), and the upper extremity motor control of Fugl-Meyer Assessment (FMA-UE), Motor Assessment Score (MAS), and the Wolf Motor Function Test (WMFT). All assessment was executed by a blinded evaluator, and data management and statistical analysis was also conducted by a blinded statistic researcher.

Inclusion Criteria:

1. at least 6 months since stroke
2. three or fewer incidents of unilateral stroke confirmed by taking the participant's medical history ability to follow researcher's instructions
3. ability to flex and extend the paretic arm and hand
4. Modified Ashworth Score (MAS) ≦3 for wrist and finger joints
5. Mini-Mental State Examination (MMSE) score should 24 or higher
6. no other orthopedic neurological disorders
7. Brunnstrom stage 3 or 4
8. no joint in other experimental rehabilitation or drug studies 21

Exclusion Criteria:

1. unstable cardiovascular conditions
2. uncontrolled hypertension (190/110 mm Hg)
3. severe orthopedic or pain conditions
4. dementia (Mini-Mental State Examination score < 22)
5. aphasia with inability to follow researcher's commands
6. severe joint contracture of bilateral upper extremities that would impact the movement performances of upper extremities