Michael S. Ferrara, W. E. Buckley and Connie L. Peterson
Jay Hertel, Craig R. Denegar, W.E. Buckley, Neil A. Sharkey and Wayne L. Stokes
To identify changes in sagittal- and frontal-plane center of pressure (COP) excursion length and velocity during single-leg stance under 6 orthotic conditions.
1 × 6 repeated-measures.
University biomechanics laboratory.
Fifteen healthy young adults without excessive forefoot, arch, or rear-foot malalignments.
Selected variables of COP length and velocity were calculated in both the frontal and sagittal planes during three 5-second trials of quiet unilateral stance.
Postural control was assessed under 6 conditions: shoe only and 5 orthotics.
The medially posted orthotic caused the least frontal COP length and velocity, and the Cramer Sprained Ankle Orthotic® caused the greatest frontal-plane sway. No significant differences were found between the different orthotic conditions in sagittal-plane measures.
Differently posted rear-foot orthotics had various effects on frontal-plane postural control in healthy participants. Further research is needed on pathological populations.
Jay Hertel, Craig R. Denegar, Phil D. Johnson, Sheri A. Hale and W.E. Buckley
Two studies were performed to estimate the reliability of the Cybex Reactor in assessing agility tasks. In Study 1, participants (n =13) underwent identical testing sessions twice in 1 week. In Study 2, participants (n = 13) underwent identical testing sessions twice in 1 week, once 3 weeks later, and once 6 weeks later. Testing sessions consisted of four identical agility tasks requiring participants to react to cues shown on a video monitor. In Study 1, intraclass correlation coefficients (ICC) were .47 for Day 1 and .75 for Day 2 for time to complete each task. Participants performed faster on Day 2 (p < .05). In Study 2, ICC ranged from .58 to .83. ICC between sessions ranged from .59 to .73. Participants performed significantly faster each successive session except between Weeks 3 and 6 (p < .05). The Reactor appears to be reliable in assessing agility tasks with test–retest intervals of up to 6 weeks.
Michael E. Powers, Bernadette D. Buckley, Thomas W. Kaminski, Tricia J. Hubbard and Cindy Ortiz
The combined effects of strength and proprioception training, especially in individuals with ankle instability, have not been studied extensively.
To examine the influence of 6 weeks of strength and proprioception training on measures of muscle fatigue and static balance in those with unilateral functional ankle instability (FAI).
Pretest–posttest, randomized groups.
A climate-controlled sports-medicine research laboratory.
38 subjects with self-reported unilateral FAI.
Muscle fatigue was determined using the median power frequency (f med) from an electromyographic signal, and static balance was assessed using center-of-pressure values obtained from a triaxial force plate.
There were no significant effects of the strength or proprioception training on our measures of muscle fatigue and static balance.
Strength training, proprioception training, and the combination of the 2 failed to improve postural-stability characteristics in a group of subjects with FAI.
Thomas P. Dompier, Craig R. Denegar, W.E. Buckley, S. John Miller, Jay Hertel and Wayne J. Sebastianelli
Flexibility is promoted as essential to physical fitness, but the mechanisms limiting it are not fully understood.
To investigate the effects of general anesthesia on hamstring extensibility.
Hospital operating room.
Eight volunteers undergoing orthopedic surgeries unrelated to the tested limb.
Three measurements of passive knee extension (PKE) taken before and after administration of general anesthesia. The force applied during the measurements was consistent between trials.
Mean PKE range of motion (ROM) was significantly greater before anesthesia (75.0° ± 11.8°) than after (53.3° ± 17°; t = 5.6, P < .001). Pearson product correlation revealed a significant correlation between the mean difference in PKE ROM between treatment conditions and subjects’ body weight (r = .91, P < .05).
The findings might be attributable to diminished neural drive to the antagonist muscle groups and suggest a more complex neural control of flexibility than simply neural drive to an agonist muscle.