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Wilfrid Laurier University Faculty of Science
October 26, 2016
Canadian Excellence


Gait over Uneven Terrain

Falls are a serious health care problem among older adults. Foot problems are one of the factors that can increase the risk of falling. My research program is targeted at understanding how foot problems affect an individual's balance. In order to isolate the underlying factors that may impair balance I have identified three specific areas that most foot problems can be categorized into. These areas are sensation from the bottom of the foot, foot mechanics and foot pain. Problems that exhibit characteristics within any of these areas can potentially effect how an individual is able to detect that they are out of balance and can also affect how successfully they can produce a balance reaction in response to becoming unstable. The focus of this pilot project is to build and test an experiment setup to simulate gait over uneven terrain. Initially, slightly inclined platforms will be constructed and placed at each foot contact position, during walking, to simulate variations in surface orientation (e.g. uneven sidewalks). Then a population of healthy young adult individuals will be tested to determine the effect of the uneven terrain on their balance control during gait. This experimental setup will be a critical component of future work in the evaluation of the postural control system to prevent falls in older adults.

Funded by a WLU Post-doctoral Fellowship Award

"Solesensor" Clinical Trials:

One of the most pervasive effects of aging is a loss of cutaneous touch and pressure sensation. The loss of cutaneous sensation in the plantar surface (sole) of the feet has been correlated with impaired postural control (poor balance) and an increased risk of falling. In order to maintain stable upright stance, the centre of gravity of the body must be positioned over the base of support established by the feet. Loss of balance and falling occur if the body weight is shifted too close to the limits of this base of support, i.e. too close to the perimeter of the plantar foot surface. Cutaneous sensation from the soles of the feet provides the central nervous system with this critical stability information. Numerous studies support the important contribution of cutaneous sensation from the plantar foot surface, in the control of postural balance. This cutaneous sensation acts, within the central nervous system, to trigger and/or modulate the automatic postural reflexes and reactions that act to prevent loss of balance.

Our research has shown that pressure sensation from the soles of the feet (plantar mechanoreceptors) plays an important role in controlling several key aspects of balancing reactions, particularly during compensatory stepping . As a result, age-related loss of plantar pressure sensation, which is very common, can lead to impaired control of these reactions. However, we have shown that it is possible to compensate for balance impairments resulting from this loss of sensation by using special footwear insoles to facilitate sensation from the perimeter of the sole. To date, we have demonstrated the feasibility of this approach in laboratory studies, and we have obtained a U.S. patent for the design concept. However, it remains to be determined whether the benefits of the footwear persist over the long term, or whether there is a habituation of the effect. Also, we need to determine whether there are any practical problems associated with wearing such footwear, e.g. due to discomfort or irritation of the skin.

Funded by a Candian Institutes of Health Research "Proof of Principle" Award

Influence of midsole material on gait termination

The purpose of this study was to determine the influence of different midsole hardnesses on dynamic balance control during unexpected gait termination.  Twelve healthy young female adults were asked to walk along an 8-m walkway, looking straight ahead.  During 25% of the trials, they were signaled (via an audio buzzer) to terminate gait within the next two steps.  The four experimental conditions were 1) soft (A15); 2) standard (A33); 3) hard (A50) and 4) barefoot.  Center of mass (COM) position relative to the lateral base of support (BOS), center of mass – center of pressure (COM-COP) difference and vertical loading rate were used to evaluate the influence of midsole material on dynamic balance control.  The results were a decrease in the medial-lateral range of COM with respect to the lateral BOS, a reduction in the maximum COM-COP difference and an increase in the vertical loading rate due to the presence and hardness level of the midsole material when compared to the barefoot condition.  The primary outcomes of this study have illustrated the influence of midsole hardness as an impediment to dynamic balance control during responses to gait termination.  In conclusion, the present study suggests that variations in midsole material and even the presence of it, impairs the dynamic balance control system.

Funded by WLU Undergraduate Research Assistantship

Foot Disorders: sensation, mechanics & pain (summary currently unavailable)
Funded by a Candian Institutes of Health Research "Development Fund" Award for WLU

Estrogen effects on balance control

This study examined the effects of hormone replacement combined with strength training on improving dynamic balance control in post-menopausal women. Thirty one participating post-menopausal women were divided into three groups (hormone replacement (HR), non-hormone replacement (NR) and control (CR) group). HR and NR groups were tested for muscle strength and balance control during gait, prior to training and following a six week lower body strength training program. Quadriceps muscle strength was evaluated as isokinetic peak torque (60 /sec) using a CYBEX NORM and balance control was evaluated by center of mass – base of support relationships and ground reaction forces during gait perturbations. Only the HR group showed significantly (p < 0.05) improved balance control during the initial phase of unexpected gait termination and single stance periods while walking across uneven terrain following training. The strength gains in the HR group tended to be greater than in the NR group over the six week training program, although neither group showed statistically significant increases. The CR group showed no significant differences between testing times. HR in post-menopausal females may enhance dynamic balance control when combined with a strength training program, even if no statistically significant gains in strength are achieved.

Funded by a Candian Institutes of Health Research "Development Fund" Award for WLU

Neural Network Modelling

This study was undertaken to determine if an Artificial Neural Network based model could be used to approximate an individual’s center of mass (COM) during dynamic movements in upright stance given only pressure data originating from pressure sensing insoles. This type of modelling may provide insight into how the human postural control system uses this sensory information to control balance. The activity was voluntary leaning in four directions (forward, right, left and backwards) all held for just over a second. The model demonstrated good prediction of the COM in the anterior/posterior direction such that the predicted COM approximation was within 10 mm of the measured COM.  Extension of this model to 2-D space, incorporating medial/lateral information, has also give a good prediction of the COM location.  Pilot work has also begun on modeling the COM and it relationship to the base of support during gait using pressure insoles; some data is presented here and has shown encouraging results as we continue to the next logical stage of development.

Funded by SHARCNet Undergraduate Fellowships

© Dr. Stephen Perry, Ph.D., WLU Biomechanics Laboratory, 2005
Last Updated: September 6, 2005 12:13