The subjects in Group B will received TENS (25Hz, 0.5mA) on the concha of left outer ear. The electrical stimulation was generated by the portable neurostimulator (Nemos®, Cerbomed, Erlangen, Germany) and was delivered by a titanium electrodes positioning on top of a silicon earplug. Previous study has shown that it was effective to improve the Accelerate extinction memory formation and retention in healthy young adults.

The subjects in Group C will receive 30 min sham electrical stimulation on T1 by a placebo-TENS device. The Placebo-TENS was applied by an apparently identical TENS unit. The unit's power indicator light was illuminated, but the unit's electrical circuit had been manually disconnected inside. In order to shape the common mindset, all subjects (except those in the Control group) were informed that they might or might not feel an electrical current, as different stimulation parameters were being applied.

The verbal short-term memory and working memory is measured by the digit span test . The subject was required to listen to a series of random numbers carefully and then repeated them in forward (forward digit span test) and backward (backward digit span test) order. Continue in the same manner by increasing the series of numbers. The difficulty will be increased when the number in a sequence increased. The forward digit span task requires verbal working memory and attention, while the backwards digit span task additionally tests cognitive control and executive function.The more correct trials performed indicated better short-term memory and work memory.

The verbal short-term memory and working memory is measured by the digit span test. The subject was required to listen to a series of random numbers carefully and then repeated them in forward (forward digit span test) and backward (backward digit span test) order. Continue in the same manner by increasing the series of numbers. The difficulty will be increased when the number in a sequence increased. The forward digit span task requires verbal working memory and attention, while the backwards digit span task additionally tests cognitive control and executive function.The more correct trials performed indicated better short-term memory and work memory.

The verbal short-term memory and working memory is measured by the digit span test . The subject was required to listen to a series of random numbers carefully and then repeated them in forward (forward digit span test) and backward (backward digit span test) order. Continue in the same manner by increasing the series of numbers. The difficulty will be increased when the number in a sequence increased. The forward digit span task requires verbal working memory and attention, while the backwards digit span task additionally tests cognitive control and executive function.The more correct trials performed indicated better short-term memory and work memory.

The visual memory is measured by the visual memory span test. The subject was required to observe a given order to tap a number of block as shown by the examiners and then repeat them in forward and backward order. The difficulty will be increased when the number of blocks in a sequence increased. The more correct trials performed indicated better visual memory.

The visual memory is measured by the visual memory span test. The subject was required to observe a given order to tap a number of block as shown by the examiners and then repeat them in forward and backward order. The difficulty will be increased when the number of blocks in a sequence increased. The more correct trials performed indicated better visual memory.

The visual memory is measured by the visual memory span test. The subject was required to observe a given order to tap a number of block as shown by the examiners and then repeat them in forward and backward order. The difficulty will be increased when the number of blocks in a sequence increased. The more correct trials performed indicated better visual memory.

The visual memory is measured by the visual memory span test. The subject was required to observe a given order to tap a number of block as shown by the examiners and then repeat them in forward and backward order. The difficulty will be increased when the number of blocks in a sequence increased. The more correct trials performed indicated better visual memory.

The ability to inhibit cognitive interference is measured by the Stroop Color and Word Test. The Stroop Test consists of 3 subtasks. The first subtask shows color dots (green, blue, yellow, red) in random order. The second subtask shows the words (green, blue, red, yellow) in random order. The third task showed color words (green, blue, red, yellow) printed in a different ink color (i.e., the word blue printed in yellow ink). Participants are required to name the color of the ink as quickly as possible within 45 s in each task. The completion time and number of error is recorded in each task. The interference ratio of will be calculated as the completion time of the third task/the completion time of the first task. A higher interference score indicated poorer interference control.

The ability to inhibit cognitive interference is measured by the Stroop Color and Word Test. The Stroop Test consists of 3 subtasks. The first subtask shows color dots (green, blue, yellow, red) in random order. The second subtask shows the words (green, blue, red, yellow) in random order. The third task showed color words (green, blue, red, yellow) printed in a different ink color (i.e., the word blue printed in yellow ink). Participants are required to name the color of the ink as quickly as possible within 45 s in each task. The completion time and number of error is recorded in each task. The interference ratio of will be calculated as the completion time of the third task/the completion time of the first task. A higher interference score indicated poorer interference control.

The ability to inhibit cognitive interference is measured by the Stroop Color and Word Test. The Stroop Test consists of 3 subtasks. The first subtask shows color dots (green, blue, yellow, red) in random order. The second subtask shows the words (green, blue, red, yellow) in random order. The third task showed color words (green, blue, red, yellow) printed in a different ink color (i.e., the word blue printed in yellow ink). Participants are required to name the color of the ink as quickly as possible within 45 s in each task. The completion time and number of error is recorded in each task. The interference ratio of will be calculated as the completion time of the third task/the completion time of the first task. A higher interference score indicated poorer interference control.

The ability to inhibit cognitive interference is measured by the Stroop Color and Word Test. The Stroop Test consists of 3 subtasks. The first subtask shows color dots (green, blue, yellow, red) in random order. The second subtask shows the words (green, blue, red, yellow) in random order. The third task showed color words (green, blue, red, yellow) printed in a different ink color (i.e., the word blue printed in yellow ink). Participants are required to name the color of the ink as quickly as possible within 45 s in each task. The completion time and number of error is recorded in each task. The interference ratio of will be calculated as the completion time of the third task/the completion time of the first task. A higher interference score indicated poorer interference control.

The visual, nonverbal long-term memory is measured by the face recognition test from the Rivermead Behavioral Memory Test (RMBT). Fifteen faces are shown successively to the subject. After an occupied interval of 5 minutes, the subjects are required to select the original 15 faces from a set of 30. The recognition score is the number of correct answers minus the number of incorrect answers. The recognition score is ranged from -15 to 15. A higher score indicated a better visual, nonverbal long term memory.

The visual, nonverbal long-term memory is measured by the face recognition test from the Rivermead Behavioral Memory Test (RMBT). Fifteen faces are shown successively to the subject. After an occupied interval of 5 minutes, the subjects are required to select the original 15 faces from a set of 30. The recognition score is the number of correct answers minus the number of incorrect answers. The recognition score is ranged from -15 to 15. A higher score indicated a better visual, nonverbal long term memory.

The visual, nonverbal long-term memory is measured by the face recognition test from the Rivermead Behavioral Memory Test (RMBT). Fifteen faces are shown successively to the subject. After an occupied interval of 5 minutes, the subjects are required to select the original 15 faces from a set of 30. The recognition score is the number of correct answers minus the number of incorrect answers. The recognition score is ranged from -15 to 15. A higher score indicated a better visual, nonverbal long term memory.

The visual, nonverbal long-term memory is measured by the face recognition test from the Rivermead Behavioral Memory Test (RMBT). Fifteen faces are shown successively to the subject. After an occupied interval of 5 minutes, the subjects are required to select the original 15 faces from a set of 30. The recognition score is the number of correct answers minus the number of incorrect answers. The recognition score is ranged from -15 to 15. A higher score indicated a better visual, nonverbal long term memory.

The visual, verbal long-term memory is measured by the picture recognition test from the RBMT. Line drawings of 15 common objects are presented one at a time. After an occupied interval of 5 minutes, the subjects are asked to select the original 15 pictures from a set of 30. The recognition score is calculated in the same way as in the Face Recognition test. The recognition score is ranged from -15 to 15. A higher score indicated a better visual, verbal long term memory.

The visual, verbal long-term memory is measured by the picture recognition test from the RBMT. Line drawings of 15 common objects are presented one at a time. After an occupied interval of 5 minutes, the subjects are asked to select the original 15 pictures from a set of 30. The recognition score is calculated in the same way as in the Face Recognition test. The recognition score is ranged from -15 to 15. A higher score indicated a better visual, verbal long term memory.

The visual, verbal long-term memory is measured by the picture recognition test from the RBMT. Line drawings of 15 common objects are presented one at a time. After an occupied interval of 5 minutes, the subjects are asked to select the original 15 pictures from a set of 30. The recognition score is calculated in the same way as in the Face Recognition test. The recognition score is ranged from -15 to 15. A higher score indicated a better visual, verbal long term memory.

The visual, verbal long-term memory is measured by the picture recognition test from the RBMT. Line drawings of 15 common objects are presented one at a time. After an occupied interval of 5 minutes, the subjects are asked to select the original 15 pictures from a set of 30. The recognition score is calculated in the same way as in the Face Recognition test. The recognition score is ranged from -15 to 15. A higher score indicated a better visual, verbal long term memory.

The functional balance ability is measured by BBS. The BBS is an ordinal scale with 14 items, each item ranged from 0-4 with a total score ranged from 0-56. The higher score indicates a better balance function. Previous study has shown that BBS has good to excellent test-retest reliability (ICC=0.77-0.886) in older adults.

The functional balance ability is measured by BBS. The BBS is an ordinal scale with 14 items, each item ranged from 0-4 with a total score ranged from 0-56. The higher score indicates a better balance function. Previous study has shown that BBS has good to excellent test-retest reliability (ICC=0.77-0.886) in older adults.

The functional balance ability is measured by BBS. The BBS is an ordinal scale with 14 items, each item ranged from 0-4 with a total score ranged from 0-56. The higher score indicates a better balance function. Previous study has shown that BBS has good to excellent test-retest reliability (ICC=0.77-0.886) in older adults.

The functional balance ability is measured by BBS. The BBS is an ordinal scale with 14 items, each item ranged from 0-4 with a total score ranged from 0-56. The higher score indicates a better balance function. Previous study has shown that BBS has good to excellent test-retest reliability (ICC=0.77-0.886) in older adults.

The walking speed over a short distance is measured by the 10MWT. The subject will be asked to walk 10 meter in a normal comfortable speed and maximum speed condition, respectively. The completion time will be records by stopwatch. Each condition will be repeated for 2 times. The completion time will be averaged. The shorter the completion time, the better performance is. 10MWT has shown excellent test-retest reliability (ICC=0.98) in assessing healthy older adults.

The walking speed over a short distance is measured by the 10MWT. The subject will be asked to walk 10 meter in a normal comfortable speed and maximum speed condition, respectively. The completion time will be records by stopwatch. Each condition will be repeated for 2 times. The completion time will be averaged. The shorter the completion time, the better performance is. 10MWT has shown excellent test-retest reliability (ICC=0.98) in assessing healthy older adults.

The walking speed over a short distance is measured by the 10MWT. The subject will be asked to walk 10 meter in a normal comfortable speed and maximum speed condition, respectively. The completion time will be records by stopwatch. Each condition will be repeated for 2 times. The completion time will be averaged. The shorter the completion time, the better performance is. 10MWT has shown excellent test-retest reliability (ICC=0.98) in assessing healthy older adults.

The walking speed over a short distance is measured by the 10MWT. The subject will be asked to walk 10 meter in a normal comfortable speed and maximum speed condition, respectively. The completion time will be records by stopwatch. Each condition will be repeated for 2 times. The completion time will be averaged. The shorter the completion time, the better performance is. 10MWT has shown excellent test-retest reliability (ICC=0.98) in assessing healthy older adults.

The aerobic capacity and walking endurance is measured by the 6MWT. The participants will be asked to walk as far as possible for 6 minutes in the 20 meters' corridor. The walking distance in 6 minutes will be records. The longer distance the subject walk, the better endurance is. The 6MWT has shown excellent test-retest reliability (ICC=0.95) in assessing healthy older adults.

The aerobic capacity and walking endurance is measured by the 6MWT. The participants will be asked to walk as far as possible for 6 minutes in the 20 meters' corridor. The walking distance in 6 minutes will be records. The longer distance the subject walk, the better endurance is. The 6MWT has shown excellent test-retest reliability (ICC=0.95) in assessing healthy older adults.

The aerobic capacity and walking endurance is measured by the 6MWT. The participants will be asked to walk as far as possible for 6 minutes in the 20 meters' corridor. The walking distance in 6 minutes will be records. The longer distance the subject walk, the better endurance is. The 6MWT has shown excellent test-retest reliability (ICC=0.95) in assessing healthy older adults.

The aerobic capacity and walking endurance is measured by the 6MWT. The participants will be asked to walk as far as possible for 6 minutes in the 20 meters' corridor. The walking distance in 6 minutes will be records. The longer distance the subject walk, the better endurance is. The 6MWT has shown excellent test-retest reliability (ICC=0.95) in assessing healthy older adults.

The functional ability is measured by TUG. The subject will be asked to stand up from the chair, walk 3 meters, turn 180°, go back to the chair and then sit down. The completion time will be recorded. The subjects need to repeat the test for 2 times. The completion time of the 2 trials will be averaged.

The functional ability is measured by TUG. The subject will be asked to stand up from the chair, walk 3 meters, turn 180°, go back to the chair and then sit down. The completion time will be recorded. The subjects need to repeat the test for 2 times. The completion time of the 2 trials will be averaged.

The functional ability is measured by TUG. The subject will be asked to stand up from the chair, walk 3 meters, turn 180°, go back to the chair and then sit down. The completion time will be recorded. The subjects need to repeat the test for 2 times. The completion time of the 2 trials will be averaged.

The functional ability is measured by TUG. The subject will be asked to stand up from the chair, walk 3 meters, turn 180°, go back to the chair and then sit down. The completion time will be recorded. The subjects need to repeat the test for 2 times. The completion time of the 2 trials will be averaged.

The level of community integration is assessed by Chinese version of Community Integration Measure (CIM). It is a self-report questionnaire that is easily administrated to assess the community integration level. The instrument consists of 10 items, each rated from 1 to 5, giving a total score ranging from 10 to 50. A higher score indicates greater community integration. Liu et al. (Liu et al., 2014) reports that the Chinese version of the CIM showed good test-retest reliability (ICC=0.84) in people with stroke. A pilot study with 123 people with chronic stroke conducted as part of this research showed that CIM scores were significantly correlated with peak wrist flexion torque (r=0.203, p<0.05), Wolf Motoro Function Test (WMFT) scores (r=0.194, p<0.05) and Barthel Index scores (r=0.194, p<0.05).

The level of community integration is assessed by Chinese version of Community Integration Measure (CIM). It is a self-report questionnaire that is easily administrated to assess the community integration level. The instrument consists of 10 items, each rated from 1 to 5, giving a total score ranging from 10 to 50. A higher score indicates greater community integration. Liu et al. reports that the Chinese version of the CIM showed good test-retest reliability (ICC=0.84) in people with stroke. A pilot study with 123 people with chronic stroke conducted as part of this research showed that CIM scores were significantly correlated with peak wrist flexion torque (r=0.203, p<0.05), WMFT scores (r=0.194, p<0.05) and Barthel Index scores (r=0.194, p<0.05).

The level of community integration is assessed by Chinese version of Community Integration Measure (CIM). It is a self-report questionnaire that is easily administrated to assess the community integration level. The instrument consists of 10 items, each rated from 1 to 5, giving a total score ranging from 10 to 50. A higher score indicates greater community integration. Liu et al. reports that the Chinese version of the CIM showed good test-retest reliability (ICC=0.84) in people with stroke. A pilot study with 123 people with chronic stroke conducted as part of this research showed that CIM scores were significantly correlated with peak wrist flexion torque (r=0.203, p<0.05), WMFT scores (r=0.194, p<0.05) and Barthel Index scores (r=0.194, p<0.05).

The level of community integration is assessed by Chinese version of Community Integration Measure (CIM). It is a self-report questionnaire that is easily administrated to assess the community integration level. The instrument consists of 10 items, each rated from 1 to 5, giving a total score ranging from 10 to 50. A higher score indicates greater community integration. Liu et al. reports that the Chinese version of the CIM showed good test-retest reliability (ICC=0.84) in people with stroke. A pilot study with 123 people with chronic stroke conducted as part of this research showed that CIM scores were significantly correlated with peak wrist flexion torque (r=0.203, p<0.05), WMFT scores (r=0.194, p<0.05) and Barthel Index scores (r=0.194, p<0.05).

The LOS is measured by the balance plate system (Bertec, Columbus, OH). During the limits of stability task, subjects were instructed to shift their weight by moving their pelvis and torso without flexing their hips or knees, keeping their heels in contact with the force plates and their arms/hands at their sides. The subjects will be instructed to shifted his or her center of mass to forward (0°), right-forward (45°), right (90°), right-backward (135°), backward (180°), left backward (225°), left (270°) and left-forward (315°), based on a visual projection of the center of mass in the current and target locations. The duration of each weight shifting trial was 10 seconds. Reaction time (RT) is used to assess the time participants take to give a movement response after cues are provided. The RT (second) in the 8 direction will be measured. The longer RT indicated poorer balance performance.

The LOS is measured by the balance plate system (Bertec, Columbus, OH). During the limits of stability task, subjects were instructed to shift their weight by moving their pelvis and torso without flexing their hips or knees, keeping their heels in contact with the force plates and their arms/hands at their sides. The subjects will be instructed to shifted his or her center of mass to forward (0°), right-forward (45°), right (90°), right-backward (135°), backward (180°), left backward (225°), left (270°) and left-forward (315°), based on a visual projection of the center of mass in the current and target locations. The duration of each weight shifting trial was 10 seconds. Reaction time (RT) is used to assess the time participants take to give a movement response after cues are provided. The RT (second) in the 8 direction will be measured. The longer RT indicated poorer balance performance.

The LOS is measured by the balance plate system (Bertec, Columbus, OH). During the limits of stability task, subjects were instructed to shift their weight by moving their pelvis and torso without flexing their hips or knees, keeping their heels in contact with the force plates and their arms/hands at their sides. The subjects will be instructed to shifted his or her center of mass to forward (0°), right-forward (45°), right (90°), right-backward (135°), backward (180°), left backward (225°), left (270°) and left-forward (315°), based on a visual projection of the center of mass in the current and target locations. The duration of each weight shifting trial was 10 seconds. Reaction time (RT) is used to assess the time participants take to give a movement response after cues are provided. The RT (second) in the 8 direction will be measured. The longer RT indicated poorer balance performance.

The LOS is measured by the balance plate system (Bertec, Columbus, OH). During the limits of stability task, subjects were instructed to shift their weight by moving their pelvis and torso without flexing their hips or knees, keeping their heels in contact with the force plates and their arms/hands at their sides. The subjects will be instructed to shifted his or her center of mass to forward (0°), right-forward (45°), right (90°), right-backward (135°), backward (180°), left backward (225°), left (270°) and left-forward (315°), based on a visual projection of the center of mass in the current and target locations. The duration of each weight shifting trial was 10 seconds. Reaction time (RT) is used to assess the time participants take to give a movement response after cues are provided. The RT (second) in the 8 direction will be measured. The longer RT indicated poorer balance performance.

The LOS is measured by the balance plate system (Bertec, Columbus, OH). During the limits of stability task, subjects were instructed to shift their weight by moving their pelvis and torso without flexing their hips or knees, keeping their heels in contact with the force plates and their arms/hands at their sides. The subjects will be instructed to shifted his or her center of mass to forward (0°), right-forward (45°), right (90°), right-backward (135°), backward (180°), left backward (225°), left (270°) and left-forward (315°), based on a visual projection of the center of mass in the current and target locations. The duration of each weight shifting trial was 10 seconds. Movement velocity (MV) is used to assess the average center of gravity (COG) displacement speed. The MV (degree/second) in the 8 direction will be measured. The smaller MV indicated poorer balance performance.

The LOS is measured by the balance plate system (Bertec, Columbus, OH). During the limits of stability task, subjects were instructed to shift their weight by moving their pelvis and torso without flexing their hips or knees, keeping their heels in contact with the force plates and their arms/hands at their sides. The subjects will be instructed to shifted his or her center of mass to forward (0°), right-forward (45°), right (90°), right-backward (135°), backward (180°), left backward (225°), left (270°) and left-forward (315°), based on a visual projection of the center of mass in the current and target locations. The duration of each weight shifting trial was 10 seconds. Movement velocity (MV) is used to assess the average center of gravity (COG) displacement speed. The MV (degree/second) in the 8 direction will be measured. The smaller MV indicated poorer balance performance.

The LOS is measured by the balance plate system (Bertec, Columbus, OH). During the limits of stability task, subjects were instructed to shift their weight by moving their pelvis and torso without flexing their hips or knees, keeping their heels in contact with the force plates and their arms/hands at their sides. The subjects will be instructed to shifted his or her center of mass to forward (0°), right-forward (45°), right (90°), right-backward (135°), backward (180°), left backward (225°), left (270°) and left-forward (315°), based on a visual projection of the center of mass in the current and target locations. The duration of each weight shifting trial was 10 seconds. Movement velocity (MV) is used to assess the average center of gravity (COG) displacement speed. The MV (degree/second) in the 8 direction will be measured. The smaller MV indicated poorer balance performance.

The LOS is measured by the balance plate system (Bertec, Columbus, OH). During the limits of stability task, subjects were instructed to shift their weight by moving their pelvis and torso without flexing their hips or knees, keeping their heels in contact with the force plates and their arms/hands at their sides. The subjects will be instructed to shifted his or her center of mass to forward (0°), right-forward (45°), right (90°), right-backward (135°), backward (180°), left backward (225°), left (270°) and left-forward (315°), based on a visual projection of the center of mass in the current and target locations. The duration of each weight shifting trial was 10 seconds. Movement velocity (MV) is used to assess the average center of gravity (COG) displacement speed. The MV (degree/second) in the 8 direction will be measured. The smaller MV indicated poorer balance performance.

The LOS is measured by the balance plate system (Bertec, Columbus, OH). During the limits of stability task, subjects were instructed to shift their weight by moving their pelvis and torso without flexing their hips or knees, keeping their heels in contact with the force plates and their arms/hands at their sides. The subjects will be instructed to shifted his or her center of mass to forward (0°), right-forward (45°), right (90°), right-backward (135°), backward (180°), left backward (225°), left (270°) and left-forward (315°), based on a visual projection of the center of mass in the current and target locations. The duration of each weight shifting trial was 10 seconds. Endpoint excursion (EE) is used to assess how far the patient leans towards the target on his or her first attempt. The EE (%) in the 8 direction will be measured. The smaller EE indicated poorer balance performance.

The LOS is measured by the balance plate system (Bertec, Columbus, OH). During the limits of stability task, subjects were instructed to shift their weight by moving their pelvis and torso without flexing their hips or knees, keeping their heels in contact with the force plates and their arms/hands at their sides. The subjects will be instructed to shifted his or her center of mass to forward (0°), right-forward (45°), right (90°), right-backward (135°), backward (180°), left backward (225°), left (270°) and left-forward (315°), based on a visual projection of the center of mass in the current and target locations. The duration of each weight shifting trial was 10 seconds. Endpoint excursion (EE) is used to assess how far the patient leans towards the target on his or her first attempt. The EE (%) in the 8 direction will be measured. The smaller EE indicated poorer balance performance.

The LOS is measured by the balance plate system (Bertec, Columbus, OH). During the limits of stability task, subjects were instructed to shift their weight by moving their pelvis and torso without flexing their hips or knees, keeping their heels in contact with the force plates and their arms/hands at their sides. The subjects will be instructed to shifted his or her center of mass to forward (0°), right-forward (45°), right (90°), right-backward (135°), backward (180°), left backward (225°), left (270°) and left-forward (315°), based on a visual projection of the center of mass in the current and target locations. The duration of each weight shifting trial was 10 seconds. Endpoint excursion (EE) is used to assess how far the patient leans towards the target on his or her first attempt. The EE (%) in the 8 direction will be measured. The smaller EE indicated poorer balance performance.

The LOS is measured by the balance plate system (Bertec, Columbus, OH). During the limits of stability task, subjects were instructed to shift their weight by moving their pelvis and torso without flexing their hips or knees, keeping their heels in contact with the force plates and their arms/hands at their sides. The subjects will be instructed to shifted his or her center of mass to forward (0°), right-forward (45°), right (90°), right-backward (135°), backward (180°), left backward (225°), left (270°) and left-forward (315°), based on a visual projection of the center of mass in the current and target locations. The duration of each weight shifting trial was 10 seconds. Endpoint excursion (EE) is used to assess how far the patient leans towards the target on his or her first attempt. The EE (%) in the 8 direction will be measured. The smaller EE indicated poorer balance performance.

The LOS is measured by the balance plate system (Bertec, Columbus, OH). During the limits of stability task, subjects were instructed to shift their weight by moving their pelvis and torso without flexing their hips or knees, keeping their heels in contact with the force plates and their arms/hands at their sides. The subjects will be instructed to shifted his or her center of mass to forward (0°), right-forward (45°), right (90°), right-backward (135°), backward (180°), left backward (225°), left (270°) and left-forward (315°), based on a visual projection of the center of mass in the current and target locations. The duration of each weight shifting trial was 10 seconds. Maximum excursion (ME) is used to assess the maximum amount the patient leaned during the trial. The ME (%) in the 8 direction will be measured. The smaller ME indicated poorer balance performance.

The LOS is measured by the balance plate system (Bertec, Columbus, OH). During the limits of stability task, subjects were instructed to shift their weight by moving their pelvis and torso without flexing their hips or knees, keeping their heels in contact with the force plates and their arms/hands at their sides. The subjects will be instructed to shifted his or her center of mass to forward (0°), right-forward (45°), right (90°), right-backward (135°), backward (180°), left backward (225°), left (270°) and left-forward (315°), based on a visual projection of the center of mass in the current and target locations. The duration of each weight shifting trial was 10 seconds. Maximum excursion (ME) is used to assess the maximum amount the patient leaned during the trial. The ME (%) in the 8 direction will be measured. The smaller ME indicated poorer balance performance.

The LOS is measured by the balance plate system (Bertec, Columbus, OH). During the limits of stability task, subjects were instructed to shift their weight by moving their pelvis and torso without flexing their hips or knees, keeping their heels in contact with the force plates and their arms/hands at their sides. The subjects will be instructed to shifted his or her center of mass to forward (0°), right-forward (45°), right (90°), right-backward (135°), backward (180°), left backward (225°), left (270°) and left-forward (315°), based on a visual projection of the center of mass in the current and target locations. The duration of each weight shifting trial was 10 seconds. Maximum excursion (ME) is used to assess the maximum amount the patient leaned during the trial. The ME (%) in the 8 direction will be measured. The smaller ME indicated poorer balance performance.

The LOS is measured by the balance plate system (Bertec, Columbus, OH). During the limits of stability task, subjects were instructed to shift their weight by moving their pelvis and torso without flexing their hips or knees, keeping their heels in contact with the force plates and their arms/hands at their sides. The subjects will be instructed to shifted his or her center of mass to forward (0°), right-forward (45°), right (90°), right-backward (135°), backward (180°), left backward (225°), left (270°) and left-forward (315°), based on a visual projection of the center of mass in the current and target locations. The duration of each weight shifting trial was 10 seconds. Maximum excursion (ME) is used to assess the maximum amount the patient leaned during the trial. The ME (%) in the 8 direction will be measured. The smaller ME indicated poorer balance performance.

The LOS is measured by the balance plate system (Bertec, Columbus, OH). During the limits of stability task, subjects were instructed to shift their weight by moving their pelvis and torso without flexing their hips or knees, keeping their heels in contact with the force plates and their arms/hands at their sides. The subjects will be instructed to shifted his or her center of mass to forward (0°), right-forward (45°), right (90°), right-backward (135°), backward (180°), left backward (225°), left (270°) and left-forward (315°), based on a visual projection of the center of mass in the current and target locations. The duration of each weight shifting trial was 10 seconds. Directional control (DC) is used to assess how much of the patient's movement was in the target direction. The DC (%) in the 8 direction will be measured. The smaller DC indicated poorer balance performance.

The LOS is measured by the balance plate system (Bertec, Columbus, OH). During the limits of stability task, subjects were instructed to shift their weight by moving their pelvis and torso without flexing their hips or knees, keeping their heels in contact with the force plates and their arms/hands at their sides. The subjects will be instructed to shifted his or her center of mass to forward (0°), right-forward (45°), right (90°), right-backward (135°), backward (180°), left backward (225°), left (270°) and left-forward (315°), based on a visual projection of the center of mass in the current and target locations. The duration of each weight shifting trial was 10 seconds. Directional control (DC) is used to assess how much of the patient's movement was in the target direction. The DC (%) in the 8 direction will be measured. The smaller DC indicated poorer balance performance.

The LOS is measured by the balance plate system (Bertec, Columbus, OH). During the limits of stability task, subjects were instructed to shift their weight by moving their pelvis and torso without flexing their hips or knees, keeping their heels in contact with the force plates and their arms/hands at their sides. The subjects will be instructed to shifted his or her center of mass to forward (0°), right-forward (45°), right (90°), right-backward (135°), backward (180°), left backward (225°), left (270°) and left-forward (315°), based on a visual projection of the center of mass in the current and target locations. The duration of each weight shifting trial was 10 seconds. Directional control (DC) is used to assess how much of the patient's movement was in the target direction. The DC (%) in the 8 direction will be measured. The smaller DC indicated poorer balance performance.

The LOS is measured by the balance plate system (Bertec, Columbus, OH). During the limits of stability task, subjects were instructed to shift their weight by moving their pelvis and torso without flexing their hips or knees, keeping their heels in contact with the force plates and their arms/hands at their sides. The subjects will be instructed to shifted his or her center of mass to forward (0°), right-forward (45°), right (90°), right-backward (135°), backward (180°), left backward (225°), left (270°) and left-forward (315°), based on a visual projection of the center of mass in the current and target locations. The duration of each weight shifting trial was 10 seconds. Directional control (DC) is used to assess how much of the patient's movement was in the target direction. The DC (%) in the 8 direction will be measured. The smaller DC indicated poorer balance performance.