The influence of accuracy constraints on EMG and kinetic variables during
gait initiation |
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Authors: | Hyeong-Dong Kim Denis Brunt Hyun Dong Je |
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Institution: | 1) Department of Physical Therapy, College of Health Science, Korea University, Republic of Korea;2) Department of Physical Therapy, Nicole Wertheim College of Nursing and Health Sciences, Florida International University, USA;3) Department of Pharmacology, College of Pharmacy, Catholic University of Daegu, Republic of Korea |
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Abstract: | Purpose] This study investigated the effects of accuracy constraints (targets) placed on
the stepping-limb heel-strike (HS) on the electromyogram (EMG) and ground reaction forces
(GRFs) during gait initiation. Subjects and Methods] Twenty healthy subjects (29.2 ±
2.9 years) were asked to begin walking or stepping over a 10-cm-high obstacle at a fast
speed. A 3-cm-diameter target was placed on the ground to dictate the position and
accuracy of the stepping-limb HS. Results] The results showed that the initiation
velocity increase in the no-target conditions was due to modulation of the stance- and
stepping-limb GRFs and a corresponding increase in the tibialis anterior (TA) activities
of both limbs before stepping-limb toe-off. This was achieved by significantly increasing
the stepping- and stance-limb TAEMG1 (determined between the onset of movement and time to
peak anteroposterior (A-P) GRF of the stepping- and stance- limb) for the no-target
conditions. It seems, therefore, that TAEMG1 and the slope to stepping-limb peak A-P GRF
contributed to the intended velocity of initiation. Conclusion] These data indicate that
gait initiation and/or stepping over an obstacle may prove to be tasks by which motor
control can be measured. The present study provides insight into the working mechanisms of
the stepping and stance limbs and shows a clear need to further investigate whether the
intact or affected limb should be used to initiate gait during rehabilitation and
prosthetic training.Key words: Electromyogram, Gait initiation, Ground reaction forces |
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