1. Use of Visual Force Feedback to Improve Digit Force Direction During Pinch Grip in Persons With Stroke: A Pilot Study 
Na Jin Seo, PhD, Heidi W. Fischer, MS, OT, Ross A. Bogey, DO, William Z. Rymer, MD, PhD, Derek G. Kamper, PhD 
Archives of Physical Medicine and Rehabilitation 
Volume 92, Issue 1, Pages (January 2011)
DOI: /j.apmr
Copyright © 2011 American Congress of Rehabilitation Medicine Terms and Conditions

2. Fig 1
For training and evaluation of the digit force direction, study participants grasped the instrumented object (A) that recorded shear force and normal force at the digit for the thumb and the index finger separately. During training, visual feedback of shear force and normal force was provided to study participants on a computer screen (B). The magnitude and direction of shear force is shown as the location of the glass, and the magnitude of normal force is shown as the height of the water in the glass for each finger. Shear force would move the glasses away from the origin. Study participants were instructed to locate the bottoms of the 2 glasses in a prescribed target circle, while keeping the water level in the glass (actual normal force) above the tick marks (required normal force) as shown in (B). Only one prescribed target circle was shown to the study participants at a time.
Archives of Physical Medicine and Rehabilitation  , 24-30DOI: ( /j.apmr )
Copyright © 2011 American Congress of Rehabilitation Medicine Terms and Conditions

3. Fig 2
The shear to normal force ratio significantly decreased (A), and the BBT score (B) and the ARAT score (C) significantly increased after the training (*P<.05 for all; mean ± SE).
Archives of Physical Medicine and Rehabilitation  , 24-30DOI: ( /j.apmr )
Copyright © 2011 American Congress of Rehabilitation Medicine Terms and Conditions

4. Fig 3
The mean ratio of shear force error to normal force before, during the 4 sessions of, and after the training (averaged for all 84 trials for each training session). Visual feedback of shear force was provided only during the training sessions. *The ratio was significantly different between the pre- and post-training evaluations, and between the first training session and the third and fourth training sessions.
Archives of Physical Medicine and Rehabilitation  , 24-30DOI: ( /j.apmr )
Copyright © 2011 American Congress of Rehabilitation Medicine Terms and Conditions

5. Fig 4
Changes in the relative electromyographic magnitude before and after the training for 4 hand muscles (FDS, EDC, FDI, thenar eminence [Thenar]). The electromyographic signals during pinch grip were rectified and normalized to the electromyographic level during the MVC for each muscle. Then, the ratio of the normalized electromyographic magnitude of each muscle to the sum of the normalized electromyographic magnitude for the 4 muscles was computed. The change in this ratio with training (the ratio after the training minus the ratio before the training) and its SE for each muscle are shown in the figure (grip force level pooled).
Archives of Physical Medicine and Rehabilitation  , 24-30DOI: ( /j.apmr )
Copyright © 2011 American Congress of Rehabilitation Medicine Terms and Conditions