Reliability and validity of modified Four Square Step Test (mFSST) performance in individuals with Parkinson's disease.

BACKGROUND: Parkinson's disease (PD) is a complex disorder marked with non-motor and motor impairments, including gait abnormalities and postural instability. As a result of balance dysfunction and postural instability, falls and injuries are common composite impairments of PD. The modified Four Square Step Test (mFSST) replaces the canes utilized in the traditional Four Square Step Test (FSST) with tape to evaluate dynamic standing balance while stepping in multiple directions. PURPOSE: Determine the reliability and validity of the mFSST in individuals with PD. METHODS: Twenty-seven participants diagnosed with PD on medication H&Y I-III, mean age 73.07 ± 6.4, completed the FSST and mFSST. Participants performed both assessments two times using the fastest time for interrater reliability and concurrent validity. To determine the test-retest reliability, participants performed the mFSST again 20-60 min following initial assessment. RESULTS: The interrater and test-retest reliability was excellent (r = 0.916-0.999, ICC2,2 = 0.96-0.99). The mFSST and FSST were highly correlated for concurrent validity (r = 0.823, p < .01). CONCLUSION: The mFSST demonstrates excellent reliability and validity while assessing dynamic standing balance in individuals with PD. The mFSST can be completed while requiring little equipment, space, and time in multiple rehabilitation settings.

Gait asymmetry pattern following stroke determines acute response to locomotor task.

BACKGROUND: Given the prevalence of gait dysfunction following stroke, walking recovery is a primary goal of rehabilitation. However, current gait rehabilitation approaches fail to demonstrate consistent benefits. Gait asymmetry, prevalent among stroke survivors who regain the ability to walk, is associated with an increased energy cost of walking and is a significant predictor of falls post-stroke. Furthermore, differential patterns of gait asymmetry may respond differently to gait training parameters. RESEARCH QUESTION: The purpose of this study was to determine whether differential responses to locomotor task condition occur on the basis of step length asymmetry pattern (Symmetrical, NPshort, Pshort) observed during overground walking. METHODS: Participants first walked overground at their self-selected walking speed. Overground data were compared against three task conditions all tested during treadmill walking: self-selected speed with 0% body weight support (TM); self-selected speed with 30 % body weight support (BWS); and fastest comfortable speed with 30 % body weight support and nonparetic leg guidance (GuidanceNP). Our primary metrics were: symmetry indices of step length, stride length, and single limb support duration. RESULTS: We identified differences in the response to locomotor task conditions for each step length asymmetry subgroup. GuidanceNP induced an acute spatial symmetry only in the NPshort group and temporal symmetry in the Symmetrical and Pshort groups. Importantly, we found the TM and BWS conditions were insufficient to impact either spatial or temporal gait symmetry. SIGNIFICANCE: Task conditions consistent with locomotor training do not produce uniform effects across subpatterns of gait asymmetry. We identified differential responses to locomotor task conditions between groups with distinct asymmetry patterns, suggesting these subgroups may require unique intervention strategies. Despite group differences in asymmetry characteristics, improvements in symmetry noted in each group were driven by changes in both the paretic and nonparetic limbs.

Pelvic excursion during walking post-stroke: A novel classification system.

BACKGROUND: Researchers and clinicians often use gait speed to classify hemiparetic gait dysfunction because it offers clinical predictive capacity. However, gait speed fails to distinguish unique biomechanical characteristics that differentiate aspects of gait dysfunction. RESEARCH QUESTION: Here we describe a novel classification of hemiparetic gait dysfunction based on biomechanical traits of pelvic excursion. We hypothesize that individuals with greater deviation of pelvic excursion, relative to controls, demonstrate greater impairment in key gait characteristics. METHODS: We compared 41 participants (61.0 ±â€¯11.2yrs) with chronic post-stroke hemiparesis to 21 non-disabled controls (55.8 ±â€¯9.0yrs). Participants walked on an instrumented split-belt treadmill at self-selected walking speed. Pelvic excursion was quantified as the peak-to-peak magnitude of pelvic motion in three orthogonal planes (i.e., tilt, rotation, and obliquity). Raw values of pelvic excursion were compared against the distribution of control data to establish deviation scores which were assigned bilaterally for the three planes producing six values per individual. Deviation scores were then summed to produce a composite pelvic deviation score. Based on composite scores, participants were allocated to one of three categories of hemiparetic gait dysfunction with progressively increasing pelvic excursion deviation relative to controls: Type I (n = 15) - minimal pelvic excursion deviation; Type II (n = 20) - moderate pelvic excursion deviation; and Type III (n = 6) - marked pelvic excursion deviation. We assessed resulting groups for asymmetry in key gait parameters including: kinematics, joint powers temporally linked to the stance-to-swing transition, and timing of lower extremity muscle activity. RESULTS: All groups post-stroke walked at similar self-selected speeds; however, classification based on pelvic excursion deviation revealed progressive asymmetry in gait kinematics, kinetics and temporal patterns of muscle activity. SIGNIFICANCE: The progressive asymmetry revealed in multiple gait characteristics suggests exaggerated pelvic motion contributes to gait dysfunction post-stroke.

Effects of hip abduction and adduction accuracy on post-stroke gait.

BACKGROUND: Gait instability often limits post-stroke function, although the mechanisms underlying this instability are not entirely clear. Our recent work has suggested that one possible factor contributing to post-stroke gait instability is a reduced ability to accurately control foot placement. The purpose of the present experiments was to investigate whether post-stroke gait function is related to the ability to accurately abduct and adduct the hip, as required for accurate foot placement. METHODS: 35 chronic stroke survivors and 12 age-matched controls participated in this experiment. Participants performed hip oscillation trials designed to quantify hip abduction/adduction accuracy, in which they lay supine and moved their leg through a prescribed range of motion in time with a metronome. Stroke survivors also performed overground walking trials at their self-selected speed. FINDINGS: 28 of the 35 stroke survivors had sufficient active range of motion to perform the prescribed hip oscillation task. In comparison to controls, these 28 stroke survivors were significantly less accurate at matching the abduction target, matching the adduction target, and moving in time with the metronome. Across these stroke survivors, a multiple regression revealed that only paretic hip abduction accuracy made a unique contribution to predicting paretic step width and paretic step period, metrics of gait performance. INTERPRETATION: The present results demonstrate that the ability to accurately abduct the hip is related to post-stroke gait performance, as predicted from a model-based gait stabilization strategy. Therefore, interventions designed to improve lower limb movement accuracy may hold promise for restoring post-stroke gait stability.

Lower Extremity Strength Is Correlated with Walking Function After Incomplete SCI.

BACKGROUND: Lower extremity strength has been reported to relate to walking ability, however, the relationship between voluntary lower extremity muscle function as measured by isokinetic dynamometry and walking have not been thoroughly examined in individuals with incomplete spinal cord injury (iSCI). OBJECTIVE: To determine the extent to which measures of maximal voluntary isometric contraction (MVIC) and rate of torque development (RTD) in the knee extensor (KE) and plantar flexor (PF) muscle groups correlate with self-selected overground walking speed and spatiotemporal characteristics of walking. METHODS: Twenty-two subjects with chronic (>6 months) iSCI participated in a cross-sectional study. Values for MVIC and RTD in the KE and PF muscle groups were determined by isokinetic dynamometry. Walking speed and spatiotemporal characteristics of walking were measured during overground walking. RESULTS: MVIC in the KE and PF muscle groups correlated significantly with walking speed. RTD was significantly correlated with walking speed in both muscle groups, the more-involved PF muscle group showing the strongest correlation with walking speed (r = 0.728). RTD in the KE and PF muscle groups of the more-involved limb was significantly correlated with single support time of the more-involved limb. CONCLUSIONS: These data demonstrate that lower extremity strength is associated with walking ability after iSCI. Correlations for the muscle groups of the move-involved side were stronger compared to the less-involved limb. In addition, PF function is highlighted as a potential limiting factor to walking speed along with the importance of RTD.

Rehabilitation of walking after stroke.

OPINION STATEMENT: Rehabilitation of walking after stroke has been investigated with a variety of interventions, which will be outlined in this review. To date, the majority of interventions have demonstrated a positive, but similar effect in the primary clinical outcome of self-selected walking speed. Consistent among the most successful interventions is a focus on the intensity of the intervention and the ability to progress rehabilitation in a structured fashion. Successful progression of rehabilitation of walking likely lies in the ability to combine interventions based on an understanding of contributing underlying deficits (eg, motor control, strength, cardiovascular endurance, and dynamic balance). Rehabilitation programs must account for the need to train dynamic balance for falls prevention. Lastly, clinicians and researchers need to measure the effects of rehabilitation on participation and health related quality of life.