The purpose of this sludy was to compare individual pedal reaclion force components following bicycle training with and without effective force feedback in subjects with unilateral cerebrovascular accident (CVA). Eight ambulatory subjects with CVA were studied on a recumbent bicycle equipped with custom-built pedals, which measure normal and tangential components of the load applied to the pedal surface. Comparisons of normal and tangential pedal reaction forces were made following 1 month of bicycle training (3 times/week for 4 weeks) during retention tests performed without feedback. The ratios of involved to contralateral (I/C ratios) force parameters were used to assess symmetry. Subjects were randomly assigned to 2 groups: (a) a feedback group that received visual/verbal feedback regarding effective force patterns, bilaterally, after each trial; and (b) a no-feedback group dial received no feedback. Two critical results were found: (a) tangential pedal forces were significantly more posteriorly directed bilaterally following training across all subjects, but the change was greater for the no-feedback group relative to the feedback group, and (b) effective force feedback training did not demonstrate improvements in the I/C ratios above that of the control group. A more posteriorly applied tangential pedal force may represent increased dorsiflexion and may suggest that bicycle training facilitated ankle control. The cyclical nature of cycling, however, may allow for natural patterns to develop without feedback or may require less frequent use of feedback based on retention test performance.
Karen L. Perell, Robert J. Gregor and A.M. Erika Scremin
Roger Bourne, Mark Halaki, Benedicte Vanwanseele and Jillian Clarke
This study investigates the hypothesis that shallow edge lifting force in high-level rock climbers is more strongly related to fingertip soft tissue anatomy than to absolute strength or strength to body mass ratio. Fifteen experienced climbers performed repeated maximal single hand lifting exercises on rectangular sandstone edges of depth 2.8, 4.3, 5.8, 7.3, and 12.5 mm while standing on a force measurement platform. Fingertip soft tissue dimensions were assessed by ultrasound imaging. Shallow edge (2.8 and 4.3 mm) lifting force, in newtons or body mass normalized, was uncorrelated with deep edge (12.5 mm) lifting force (r < .1). There was a positive correlation (r = .65, p < .05) between lifting force in newtons at 2.8 mm edge depth and tip of bone to tip of finger pulp measurement (r < .37 at other edge depths). The results confirm the common perception that maximum lifting force on a deep edge (“strength”) does not predict maximum force production on very shallow edges. It is suggested that increased fingertip pulp dimension or plasticity may enable increased deformation of the fingertip, increasing the skin to rock contact area on very shallow edges, and thus increase the limit of force production. The study also confirmed previous assumptions of left/right force symmetry in climbers.