In young healthy adults, characteristic obstacle avoidance reflexes (stumble corrective) were elicited with electrical stimulation during walking that were dependent on the anatomical location of cutaneous afferents stimulated (sole versus dorsum of the foot). We previously demonstrated an age-related erosion of these stumble corrective responses when the perturbation was applied to the dorsum of the foot. However, it is unknown whether similar age-related reflex erosion is present with stimulation to the sole of the foot. The purpose of this study was to identify age-dependent differences in stumbling reactions to electrically evoked stimulation of the tibial nerve at the ankle during walking in healthy young (19-39) and older adult (70 years and older) groups. Electromyograms (EMG) of the tibialis anterior (TA), soleus (SOL), medial gastrocnemius (MG), biceps femoris (BF) and vastus lateralis (VL) were recorded along with gait kinematics including angular displacement and velocity at the ankle and knee joint as well as toe clearance relative to the walking surface. The main finding of this study was the significant erosion of the kinematic and EMG stumbling reactions seen in the older adults compared to the young. Specifically, during mid-swing phase, there was reduced peak toe clearance and significantly smaller amplitudes in ankle dorsiflexion and knee flexion angular displacement as well as absent responses in TA and MG in older adults compared to the young. Further, these degraded responses were superimposed on altered mid-swing phase kinematics during unstimulated walking in the older adults showing reduced toe clearance, knee flexion and increased ankle dorsiflexion compared to the young. This combination of degraded reflexes and altered unstimulated kinematics resulted in significantly reduced toe clearance in the older adults and could suggest that these adults are in the prodromal stage of fall risk. / Graduate / 0566
| Identifer | oai:union.ndltd.org:uvic.ca/oai:dspace.library.uvic.ca:1828/5551 |
| Date | 13 August 2014 |
| Creators | Gaur, Amit |
| Contributors | Hundza, Sandra R., Klimstra, Marc D. |
| Source Sets | University of Victoria |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Rights | Available to the World Wide Web, http://creativecommons.org/licenses/by-nc-nd/2.5/ca/ |
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