Springer S.1, Gottlieb U.2
1Ariel University, Ariel, Israel, 2Israel Defense Force Medical Corps, Zrifin, Israel
Background: Recurrent ankle sprains occur in up to 70% of individuals that have previously experienced a lateral ankle sprain. Individuals who report on residual symptoms which include repetitive episodes of ankle joint instability and feeling of 'giving way' have been termed as having chronic ankle instability (CAI). The cause of these symptoms and the high level of ankle sprain recurrence is not fully understood. Recent evidence suggests that deficits in central neural sensorimotor integration may contribute to the difficulties in movement control in people with CAI. Based on the understanding that in many daily activities even a fully intact motor control system requires attention and cognitive resources, studies have used the dual task (DT) paradigm to provide insight into the attentional demands of postural control and gait. Another method to test the flexibility and performance of the central nervous system for controlling gait is by challenging situations such as walking at different speeds.
Purpose: The aim of this study was to compare the effects of DT and walking speed on gait variability in individuals with and without CAI.
Methods: Sixteen subjects with CAI and 16 age- and gender-matched, able-bodied controls participated in this study. Stride time variability (STV) and stride length variability (SLV) were measured under the following four different conditions while the subjects walked on a treadmill: self-paced (SP) walking speed, SP walking with arithmetic dual-task (DT), fast walking speed, and fast walking with arithmetic DT. Two separate mixed model ANOVAs were performed in order to examine the effect of group (CAI/controls) and the two within subject factors (DT and gait speed), on STV and SLV. Analyses of variances were followed by Post hoc analysis with Bonferroni corrections, as appropriate.
Results: Under SP walking condition (without DT) there was no difference in STV between the groups (p=0.346). The healthy controls group displayed a decrease in STV when the SP speed condition was compared to SP speed with DT (p=0.011) or fast speed (p= 0.016), however, additional complexity in walking, such as in fast walking with DT, did not further change STV. In contrast, subjects with CAI did not reduce their SP STV in comparison to SP speed with DT and fast speed conditions; yet, significant decrease in STV was demonstrated in fast walking with DT (p=0.007). SLV did not change at any condition in both groups.
Conclusion(s): The results of the present study shows that both, subjects with CAI and healthy controls reduced their STV in response to challenging walking conditions, however, the pattern of change was different. A higher threshold of gait disturbance was required to cause STV reduction in the CAI group compared to healthy individuals. This higher threshold may indicate on central sensorimotor difficulty to reorganize movement pattern under varying gait conditions.
Implications: Physical therapist can use this information and employ activities that may enhance sensorimotor control during gait when designing intervention programs for people with CAI.
Funding acknowledgements: University internal funding
Topic: Musculoskeletal: lower limb
Ethics approval: The study was approved by Israel-Defense-Force Medical Corps Ethical Review Board (IDF-1482-2014). The study was registered with Clinical-Trials network (NCT02745834).
All authors, affiliations and abstracts have been published as submitted.
