Effects of Age and Sex on the Electromyographic Reaction Time of Tibialis Anterior Muscle Contraction

OBJECTIVE: Compared to elderly men, elderly women have substantially reduced performance of postural balance and greater risk of falls. To investigate the effect of age and sex on electromyographic (EMG) reaction time of tibialis anterior muscle contraction. METHOD: Fifty-nine elderly subjects and 29 young subjects participated in this study. Subjects were instructed to dorsiflex the ankle of the dominant leg as forcefully and quickly as possible in response to audible beeps. EMG activity was recorded over the tibialis anterior muscle and delays in initiation and termination of EMG signal were measured by two examiners. Mean and intrasubject variability of each delay were used as outcome measures. RESULTS: Both the intra-examiner and inter-examiner reliability of delay variables were above 0.97. Delays in initiation and termination of muscle contraction, as well as their intrasubject variability, were significantly greater in the elderly (p<0.01). However, there were no sex differences or interaction in all outcome measures. CONCLUSION: These results demonstrate that the EMG reaction time and their variability increase in the elderly population with no sex difference.

Dynamic Foot Pressure Measurement in Parkinson's Disease with Foot Scan System

BACKGROUND: Foot Scan System (RS scan international cooperation) measuring the plantar pressure distribution is simple and inexpensive tool for gait analysis. The analysis of plantar pressure distribution of the feet during gait maybe helps the assessment of motor symptoms or gait stability of Idiopathic Parkinson's disease (IPD). METHODS: We compared the parameters of foot scan system between 34 normal controls and 23 IPD patients before and after levodopa administration. Data of plantar force distribution and time of stance phase were collected using pressure-sensitive insoles as parts of the Foot Scan System. RESULTS:There were significant difference between normal controls and IPD patients in fore foot peak pressure/rear foot peak pressure ratio, time percentage of heel strike phase, mid stance phase, propulsion phase in stance phase. But in these parameters there were no significant difference between IPD patients before dopamine with after dopamine medication. CONCLUSIONS: Using the Foot Scan System (RS scan international cooperation) measuring the plantar pressure distribution, we showed that F/R ratio and time percentage of propulsion phase are reduced significantly in patients with IPD, which enables us to understand the features of gait in IPD patients more easily.

Manipulation Performance and Satisfaction of the Computer Mouse Interface in the Cervical Spinal Cord Injury Patients

OBJECTIVE: This paper aims at investigating the fitness of available computer mouse interfaces to each level of cervical spinal cord injury (SCI) patients ranging from C4 to C7. METHOD: Several commercially available computer mouse interfaces were selected for performance evaluation. They were head pointer, touch screen, button mouse, big-ball mouse, and mouse pad. Usual mouse with rubber pad was also tested for the C6-C7 SCI patients. The performance of each interface was evaluated in terms of average click rate of moving target box and patient's satisfaction. RESULTS: The results that the touch screen and the head pointer were superior to other interfaces in terms of click rate. However, in terms of the satisfaction ratio, C4-C5 SCI patients preferred the head pointer and C6-C7 SCI patients preferred the big-ball mouse. The difference in click rate and satisfaction ratio was attributed to the convenience of the interface, i.e., the necessity and type of orthosis when using the mouse interface. CONCLUSION: The results showed that the patients' preference was determined mainly by the convenience. Therefore, the convenience of the interface must be fully considered in the design and selection of computer interface for the SCI patients.