Recent evidence suggests that impaired central sensorimotor integration may contribute to deficits in movement control experienced by people with chronic ankle instability (CAI). This study compared the effects of dual-task and walking speed on gait variability in individuals with and without CAI. Sixteen subjects with CAI and 16 age- and gender-matched, able-bodied controls participated in this study. Stride time variability and stride length variability were measured on a treadmill under four different conditions: self-paced walking, self-paced walking with dual-task, fast walking, and fast walking with dual-task. Under self-paced walking (without dual-task) there was no difference in stride time variability between CAI and control groups (P = 0.346). In the control group, compared to self-paced walking, stride time variability decreased in all conditions: self-paced walking with dual-task, fast speed, and fast speed with dual-task (P = 0.011, P = 0.016, P = 0.001, respectively). However, in the CAI group, compared to self-paced walking, decreased stride time variability was demonstrated only in the fast speed with dual-task condition (P = 1.000, P = 0.471, P = 0.008; respectively). Stride length variability did not change under any condition in either group. Subjects with CAI and healthy controls reduced their stride time variability in response to challenging walking conditions; however, the pattern of change was different. A higher level of gait disturbance was required to cause a change in walking in the CAI group compared to healthy individuals, which may indicate lower adaptability of the sensorimotor system. Clinicians may use this information and employ activities to enhance sensorimotor control during gait, when designing intervention programs for people with CAI. The study was registered with the Clinical Trials network (registration NCT02745834, registration date 15/3/2016).

Inadequate quadriceps strength following anterior cruciate ligament reconstruction (ACLR) often results in alterations in gait pattern that are usually reported during loading response. Neuro-muscular electrical stimulation (NMES) is frequently used to overcome this quadriceps weakness. Despite the beneficial effects of NMES, persistent deficits in strength and gait are reported. The aim of this study was to investigate the feasibility of applying quadriceps functional electrical stimulation (FES) during walking in addition to standard rehabilitation, in the initial stage of ACLR rehabilitation. Subjects were randomized to quadriceps FES synchronized with walking group (n = 10) or quadriceps NMES (duty cycle of 10 s on/10 s off) group (n = 13). Both interventions were performed for 10 min three days a week, in addition to a standard rehabilitation program. Assessments were performed up to 2 weeks before the ACLR (pre-ACLR), and 4 weeks postoperatively. Outcomes measured were gait speed, single limb stance gait symmetry, quadriceps isometric peak strength ratio (peak strength at 4 weeks/peak strength pre-ACLR) and peak strength inter-limb symmetry. Gait outcomes were also assessed 1-week post-surgery. Subjects in both groups regained pre-ACLR gait speed and symmetry after 4 weeks of rehabilitation, with no difference between groups. However, although pre-ACLR quadriceps peak strength was similar between groups (FES - 205 Nm, NMES − 225 Nm, p = 0.605), subjects in the FES group regained 82% of their pre-quadriceps strength compared to 47% in the NMES group (p = 0.02). In addition, after 4 weeks, the FES group had significantly better inter-limb strength symmetry 0.63 ± 0.15 vs. 0.39 ± 0.18 in the NMES group (p = 0.01). Quadriceps FES combined with traditional rehabilitation is a feasible, early intervention treatment option, post-ACLR. Furthermore, at 4 weeks post-surgery, FES was more effective in recovering quadriceps muscle strength than was NMES. While spatiotemporal gait parameters did not differ between groups, kinetic and kinematic studies may be useful to further understand the effects of quadriceps FES post-ACLR. The promising results of this preliminary investigation suggest that such studies are warranted. ISRCTN 02817399 . First posted June 29, 2016.

Backward walking offers a unique challenge to balance and ambulation. This study investigated the characteristics of spatiotemporal gait factors and ankle kinematics during backward walking in people with chronic ankle instability. Sixteen subjects with chronic ankle instability and 16 able-bodied controls walked on a treadmill at their self-selected speed under backward and forward walking conditions. Gait speed, cadence, double limb support percentage, stride time variability, and three-dimensional ankle kinematics were compared between groups and conditions. During backward walking, both groups had significantly slower gait speed, lower cadence, and greater stride time variability. In addition, under backward walking condition, subjects in both groups demonstrated significant sagittal and frontal kinematic alternations, such as greater dorsiflexion and inversion following initial contact (0–27.7%, 0–25.0% of gait cycle respectively, p < 0.001). However, there were no significant differences between groups in any of the measured outcomes. This indicates that subjects with chronic ankle instability adapt to self-selected speed backward walking similarly to healthy controls. Assessments with more challenging tasks, such as backward walking with dual task and backward walking at fast speed, may be more appropriate for testing gait impairments related to chronic ankle instability.

Background: Chronic ankle instability (CAI) is attributed to functional instability driven by insufficient proprioception. However, it is not clear whether the deficits are related to global impaired performance or to specific decrease in ankle motor‐control. The aim of this study was to assess the correlation between lower limb postural control and upper limb position sense among people with CAI, in order to further explore the function of the central neural control in people with CAI.Methods: Fourteen participants (10 males, 4 females) with self‐reported CAI and 14 age‐ and gender‐matched, healthy controls participated in this study. Each participant completed single‐limb stance postural control tests and shoulder position sense tests. The Overall Stability Index (OSI) was used as a measure of postural stability. The average of the absolute error score (AES) was calculated as a measure of shoulder position sense. Pearson correlations between the scores of the four body sites –lower limb postural stability (preferred/non‐preferred), shoulder (preferred/non‐preferred) were determined separately for each group.Results: In the control group, significant correlations were found between the OSI score of the right and left ankles (r = 0.887, p < 0.001), between the AES of the right and left shoulders (r = 0.656, p = 0.011), as well as between the OSI score and the AES of the non‐preferred side (r = 0.649, p = 0.012). In the CAI group, significant correlation was found only between the OSI score at both ankles (r = 0.6, p = 0.002).Conclusions: Individuals with CAI demonstrated lower limb postural control and upper limb position sense similar to those shown in healthy controls. However, correlations between the lower and upper limbs were observed only in the healthy controls. Clinicians can use this information and employ activities that focus on coordinating the upper and lower extremities when designing neuromuscular control training programs for people with CAI.

The study objective was to determine whether spatiotemporal gait parameters could predict lower-limb overuse injuries in cohort of combat soldiers during first year of military service. Newly recruited infantry soldiers walked on a treadmill at a 15° incline with a fixed speed of 1.67 m/sec while wearing a standard military vest with a 10 kg load. Stride time variability, stride length variability, step length asymmetry, and the duration of the loading response phase of the gait cycle were measured. Injury data on 76 soldiers who did not report musculoskeletal complaints at initial screening were collected one year after recruitment. Multiple logistic regression analyses were conducted to determine the predictive effect of the gait parameters on lower-limb injuries. Twenty-four soldiers (31.6%) had overuse injuries during the first year after recruitment. Duration of the loading response was a significant predictor of general lower-limb injury (p<0.05), as well as of foot/ankle and knee injuries (p<0.05,p<0.01, resp.). A cutoff value of less than 12.15% for loading response duration predicted knee injuries with 83% sensitivity and 67% specificity. This study demonstrates the utility of spatiotemporal gait evaluation, a simple screening tool before military training, which may help to identify individuals at risk of lower-limb overuse injuries.

Background: Altered walking patterns are often described in individuals with chronic ankle instability (CAI). Contemporary treatment paradigms recommend backward walking (BW) to improve locomotion in people with musculoskeletal disorders. The purpose of this study was to determine whether muscle activity and activation variability during BW differs between subjects with and without CAI. Methods: Sixteen participants with CAI and 16 healthy controls walked on a treadmill at their self-selected speed under BW and forward walking (FW) conditions. Surface electromyography (EMG) data for the peroneus longus, tibialis anterior, medial gastrocnemius and gluteus medius muscles were collected. EMG amplitude normalized to maximum voluntary isometric contraction (%MVIC) and the standard deviation (SD) of the %MVIC EMG amplitude was calculated throughout the gait cycle. In addition, the area under the curve (AUC) of the %MVIC EMG amplitude was calculated before and after initial contact (pre-IC: 90–100% of stride; post-IC: 0–10% of stride). Results: No differences between groups were noted in the %MVIC amplitude or activation variability (SD of %MVIC EMG) under BW or FW. In both groups, decreased tibialis anterior (p < 0.001) and gluteus medius (p = 0.01), and increased medial gastrocnemius (p < 0.001) activation were observed during pre- and post-IC under BW condition. Conclusion: Participants with CAI and healthy controls have similar muscle activity patterns during BW. Yet, the results should be interpreted with caution due to the heterogeneity of the CAI population.