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The effect of ankle taping on ground reaction forces during drop landings
300 THE EFFECT
Abstracts
OF ANKLE TAPING Steven T. McCaw S Kyle H. Biomechanics Lab, Dept of Illinois State University,
ON GROUND REACTION Johnson HPERD Normal, Ill 61761
FORCES DURING DROP LANDINGS
Ankle is used to maintain the inversion range of motion (ROM) within . _ _taping . . . . _ . __ _ __ . _ limits _.. anatomical limits, preventing a strain or tne anxle ligaments. However, taping also the dorsiflexion ROM, possibly restricting the ankle's contribution to energy absorption. The purpose of this pilot study was to evaluate the effect of ankle taping on selected vertical GRF variables during controlled landings. Three male basketball players performed 10 drop landings from 60 cm under 4 conditions: Cl) Pre-ankle tape; C2) Immeadiately following ankle taping; C3) After 15 minutes of running; C4) Post-tape removal. Variables describing the maximum forefoot (Fl) and rearfoot (F2) impact forces and the times associated with these events (Tl and T2) were measured from the vertical GRF data for each trial (sampled at 1000 Hz). Ankle ROM was measured with a manual goniometer. The mean and SD were calculated for each subject/condition, and for each condition across subjects. No obvious trends were evident in the group mean data for either the force or temporal variables. Ankle ROM was reduced during taped conditions (C2 and C3). A consistent pattern of taping effects on magnitude and timing of GRF data was evident in individual subject data. Fl and Tl exhibited only minimal changes across conditions. F2 and T2 values tended to be higher (4.6%) and shorter (7.2%) from Cl to C2. F2 values tended to be lower (8.8%) and T2 values higher (9.3%) from C3 to C4. The observed trends in F2 and T2 suggest that taping disrupts the ankle's contribution to energy absorption during landing performance. A kinetic and energetic analysis appears warranted to determine how ankle taping affects ankle, knee and hip joint contributions to shock absorption. Supported
in part by a Jump Rope for Heart Grant
KINEMATIC &GRFALIGNMENT:
from the Illinois
TOWARDTBEELIMINATION
ARPERD.
OFSYNCBRONIZATION ERROR
Brian J. O’Connor, H. John Yack, Scott C. White Department of Physical Therapy & Exercise Science State University of New York at Buffalo, Buffalo, New York. The accuracy of joint force, moment and power calculations based on ground reaction force (GRF) and kinematic data depends upon the precision with which these data can be aligned. To perform these biomechanical calculations, it is necessary to identity the GRF data that occurred during a particular video image. Alignment can be accomplished by marking the video record with an LED, and marking the A/D force record with a step voltage that drives the LED. By aligning the point where the LED first illuminates with the point where the step voltage goes high, it is possible to match these data. The maximum potential error for this strategy is l/60* second (one video picture). This level of timing error can cause substantial differences in joint forces, moments and powers. To improve alignment of the GRF and kinematics, the video voltage output must be A/D converted along with force and synchronization data. Vertical blanking intervals (VBI) in the video, which repeat for each picture, can be readily identified from the A/D converted video data. Knowledge ofthese VBI'smake it possible to identity more precisely where the video images occurred in time. Combining this knowledge with the A/D converted synchronization data allows for alignment of kinematic and GRF data, to within l/1200* second. These improvements in alignment of the data leads to greater precision in the calculations of joint forces, moments and powers.
EFFECT OF UNCERTAINTIES ON JOINT I'IOMENTESTIMATION IN CEREBRAL PALSY GAIT M.P.Kadaba, H.X. Ramakrishnan, M.E.Wootten, D.Jacobs, and J.Burn Orthopaedic Engineering and Research Center, Helen Hayes Hospital, West Haverstraw, NY 10993, USA. Lower extremity joint moments estimated during gait can be useful in understanding the changes in gait patterns due to neuromuscular pathology. The accuracy of estimation of joint moments is influenced by factors related to the measurement system as well as the characteristics of the joint models used to describe the kinematics of lower extremities. In this paper using sensitivity analysis, we examine the effects of uncertainties in joint center estimation and the definition and construction of embedded axes on both the pattern and magnitude of hip, knee and ankle joint moments. Kinematic and kinetic data of I5 cerebral palsy patients were used in the sensitivity analysis. First, hip, knee and ankle joint centers were perturbed 20, 10, and 1Omm respectively in the three coordinate directions and joint moments were recomputed for each case. Average percent error in the peak joint moments varied from 11 to 39%. Next, the flexion-extension axis (embedded axis) at each joint was perturbed + or - 15 degrees in the transverse plane from a reference position and moments were recomputed. Average percent error in the peak moments varied from 6 to 50% and a marked change in joint moment pattern was observed. In view of these results, it is important to take into account the effect of uncertainties in the estimation of joint center and definition of embedded axes in interpreting joint moment data.
Abstracts
OF ANKLE TAPING Steven T. McCaw S Kyle H. Biomechanics Lab, Dept of Illinois State University,
ON GROUND REACTION Johnson HPERD Normal, Ill 61761
FORCES DURING DROP LANDINGS
Ankle is used to maintain the inversion range of motion (ROM) within . _ _taping . . . . _ . __ _ __ . _ limits _.. anatomical limits, preventing a strain or tne anxle ligaments. However, taping also the dorsiflexion ROM, possibly restricting the ankle's contribution to energy absorption. The purpose of this pilot study was to evaluate the effect of ankle taping on selected vertical GRF variables during controlled landings. Three male basketball players performed 10 drop landings from 60 cm under 4 conditions: Cl) Pre-ankle tape; C2) Immeadiately following ankle taping; C3) After 15 minutes of running; C4) Post-tape removal. Variables describing the maximum forefoot (Fl) and rearfoot (F2) impact forces and the times associated with these events (Tl and T2) were measured from the vertical GRF data for each trial (sampled at 1000 Hz). Ankle ROM was measured with a manual goniometer. The mean and SD were calculated for each subject/condition, and for each condition across subjects. No obvious trends were evident in the group mean data for either the force or temporal variables. Ankle ROM was reduced during taped conditions (C2 and C3). A consistent pattern of taping effects on magnitude and timing of GRF data was evident in individual subject data. Fl and Tl exhibited only minimal changes across conditions. F2 and T2 values tended to be higher (4.6%) and shorter (7.2%) from Cl to C2. F2 values tended to be lower (8.8%) and T2 values higher (9.3%) from C3 to C4. The observed trends in F2 and T2 suggest that taping disrupts the ankle's contribution to energy absorption during landing performance. A kinetic and energetic analysis appears warranted to determine how ankle taping affects ankle, knee and hip joint contributions to shock absorption. Supported
in part by a Jump Rope for Heart Grant
KINEMATIC &GRFALIGNMENT:
from the Illinois
TOWARDTBEELIMINATION
ARPERD.
OFSYNCBRONIZATION ERROR
Brian J. O’Connor, H. John Yack, Scott C. White Department of Physical Therapy & Exercise Science State University of New York at Buffalo, Buffalo, New York. The accuracy of joint force, moment and power calculations based on ground reaction force (GRF) and kinematic data depends upon the precision with which these data can be aligned. To perform these biomechanical calculations, it is necessary to identity the GRF data that occurred during a particular video image. Alignment can be accomplished by marking the video record with an LED, and marking the A/D force record with a step voltage that drives the LED. By aligning the point where the LED first illuminates with the point where the step voltage goes high, it is possible to match these data. The maximum potential error for this strategy is l/60* second (one video picture). This level of timing error can cause substantial differences in joint forces, moments and powers. To improve alignment of the GRF and kinematics, the video voltage output must be A/D converted along with force and synchronization data. Vertical blanking intervals (VBI) in the video, which repeat for each picture, can be readily identified from the A/D converted video data. Knowledge ofthese VBI'smake it possible to identity more precisely where the video images occurred in time. Combining this knowledge with the A/D converted synchronization data allows for alignment of kinematic and GRF data, to within l/1200* second. These improvements in alignment of the data leads to greater precision in the calculations of joint forces, moments and powers.
EFFECT OF UNCERTAINTIES ON JOINT I'IOMENTESTIMATION IN CEREBRAL PALSY GAIT M.P.Kadaba, H.X. Ramakrishnan, M.E.Wootten, D.Jacobs, and J.Burn Orthopaedic Engineering and Research Center, Helen Hayes Hospital, West Haverstraw, NY 10993, USA. Lower extremity joint moments estimated during gait can be useful in understanding the changes in gait patterns due to neuromuscular pathology. The accuracy of estimation of joint moments is influenced by factors related to the measurement system as well as the characteristics of the joint models used to describe the kinematics of lower extremities. In this paper using sensitivity analysis, we examine the effects of uncertainties in joint center estimation and the definition and construction of embedded axes on both the pattern and magnitude of hip, knee and ankle joint moments. Kinematic and kinetic data of I5 cerebral palsy patients were used in the sensitivity analysis. First, hip, knee and ankle joint centers were perturbed 20, 10, and 1Omm respectively in the three coordinate directions and joint moments were recomputed for each case. Average percent error in the peak joint moments varied from 11 to 39%. Next, the flexion-extension axis (embedded axis) at each joint was perturbed + or - 15 degrees in the transverse plane from a reference position and moments were recomputed. Average percent error in the peak moments varied from 6 to 50% and a marked change in joint moment pattern was observed. In view of these results, it is important to take into account the effect of uncertainties in the estimation of joint center and definition of embedded axes in interpreting joint moment data.