Predictive balance control during backward walking and effects of a haptic input based intervention on predictive balance control during walking
Background Falls are a leading cause of injuries and hospitalizations in individuals globally and in Canada. Even though falls can occur during any activity, a majority of falls occur during walking. Understanding and improving balance control during walking can help reduce falls. One way of improving balance control may be to add haptic input during walking and including backward and tandem walking in gait training programs. Purpose The overall purpose of this study was to examine the balance control and sensorimotor integration during backward walking as well as study the effects of an intervention consisting of backward and tandem walking on balance control in healthy adults. Methods and results Study one: Test-retest reliability, standard error of measurement, and minimal detectable change were computed for spatiotemporal and balance control measures for forward, backward, and tandem walking for fifteen healthy adults. The results demonstrated moderate to excellent reliability for all spatiotemporal and balance measures but low to poor reliability for variability measures for forward, backward, and tandem walking. Study two: Differences in spatiotemporal and balance control measures between forward and backward walking and the correlation of backward walking velocity with biomechanical balance control measures during forward and tandem walking were examined in fifty-five healthy adults. Backward walking was significantly different in terms of spatiotemporal and balance control measures compared to forward walking. Participants walked significantly slower and with a significant reduction in relative double support time during backward walking compared to forward walking. Step length and anteroposterior margin of stability were significantly reduced, and step width and mediolateral margin of stability were significantly increased during backward walking compared to forward walking. Backward walking was also significantly more variable compared to forward walking. Step length, step width, and anteroposterior and mediolateral margins of stability were significantly more variable during backward walking compared to forward walking. Velocity during backward walking showed a significant positive correlation with anteroposterior margin of stability and velocity during forward walking and a significant negative correlation with step length variability during forward walking. Study three: The effects of vision and haptic input added with haptic anchors during backward walking was examined in 55 healthy adults. It was observed that walking backward with eyes closed significantly changed spatiotemporal and balance control measures compared to walking with eyes open. Participants walked slower, with an increased amount of double support time, reduced step length, and increased step width when walking backward with eyes closed compared to walking with eyes open. Variability of step width and margin of stability in the anteroposterior and mediolateral directions were also significantly higher when walking backward with eyes closed. Margin of stability in the mediolateral direction was significantly lower when walking backward with the haptic anchors compared to walking without haptic anchors. An interaction between vision and haptic input revealed that step length was significantly lower when walking backward using the haptic anchors compared to walking without haptic anchors in the eyes open condition. Study four: This study examined the effects of a six-week (three days/week) intervention on balance control during forward, backward, and tandem walking in a total of forty-five healthy adults. Fifteen participants completed the intervention using haptic anchors, another fifteen completed the same intervention without the haptic anchors, and a control group of fifteen participants did not complete the intervention. The intervention consisted of performing ten trials each of backward and tandem walking with eyes closed over a distance of ten meters in random order at the participants’ preferred speed. During forward walking, change in step length variability was significantly higher in the eyes closed condition compared to the eyes open condition. During backward walking, velocity, %DS, and step length change scores were significantly higher in the eyes closed condition compared to eyes open and the change score for AP MOS was significantly higher in the eyes closed condition compared to the eyes open condition only for the group that trained without the haptic anchors. During tandem walking, change score for ML MOS was significantly lower in the eyes closed condition compared to the eyes open condition. No significant effects of the intervention were observed on any measures for forward, backward, and tandem walking except the AP MOS change scores in the group that performed the intervention without using the haptic anchors. Conclusion This thesis provided novel evidence on the reliability of spatiotemporal and balance control measures across three different walking styles. The findings provide support in favour of using MOS measures as well as backward walking to assess mobility and integrity of the balance control system. The insignificant effects of the haptic input based intervention warrants further research on the long-term use of haptic anchors to improve balance control.
balance control, haptic input, backward walking, forward walking, tandem walking, haptic anchors, predictive balance control
Doctor of Philosophy (Ph.D.)