Diverse Plantarflexor Module Characteristics Influence Immediate Effects of Plastic Ankle-Foot Orthosis on Gait Performance in Patients With Stroke: A Cross-sectional Study.

OBJECTIVE: To investigate the immediate effects of plastic ankle-foot orthosis (AFO) on locomotor performance in patients with stroke and determine how such effects might undergo alteration when distinct plantarflexor (PF) module subtypes are considered. DESIGN: Cross-sectional study. SETTING: Two university hospitals. PARTICIPANTS: Fifty-two patients with stroke and 21 of those without stroke (N=73). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Motor modules were identified through non-negative matrix factorization, and participants were classified into 3 groups: independent-normal-timing, independent-altered-timing, and merged PF modules. To assess the effects of the AFO, gait measurements reflecting locomotor performance were obtained with and without the presence of the plastic AFO for each group. RESULTS: The independent-altered-timing group had increased paretic propulsion, greater non-paretic step length, and faster walking speed after the administration of the plastic AFO; however, these significant changes were not observed in the independent-normal-timing and merged PF module groups. Notably, patients in the independent-normal-timing and merged PF module groups exhibited longer paretic stance times. CONCLUSION: This study suggests that the immediate effects of plastic AFO depend on the PF module subtype. These findings can potentially guide clinical decision-making regarding AFO selection for stroke rehabilitation in patients with diverse gait control characteristics.

Effects of ankle joint degree of freedom of knee-ankle-foot orthoses on loading patterns and triceps surae muscle activity on the paretic side in individuals with subacute severe hemiplegia: a retrospective study.

BACKGROUND: Individuals with subacute severe hemiplegia often undergo alternate gait training to overcome challenges in achieving walking independence. However, the ankle joint setting in a knee-ankle-foot orthosis (KAFO) depends on trunk function or paralysis stage for alternate gait training with a KAFO. The optimal degree of ankle joint freedom in a KAFO and the specific ankle joint conditions for effective rehabilitation remain unclear. Therefore, this study aimed to investigate the effects of different degrees of freedom of the ankle joint on center-of-pressure (CoP) parameters and muscle activity on the paretic side using a KAFO and to investigate the recommended setting of ankle joint angle in a KAFO depending on physical function. METHODS: This study included 14 participants with subacute stroke (67.4 ± 13.3 years). The CoP parameters and muscle activity of the gastrocnemius lateralis (GCL) and soleus muscles were compared using a linear mixed model (LMM) under two ankle joint conditions in the KAFO: fixed at 0° and free ankle dorsiflexion. We confirmed the relationship between changes in CoP parameters or muscle activity under different conditions and physical functional characteristics such as the Fugl-Meyer Assessment of Lower Extremity Synergy Score (FMAs) and Trunk Impairment Scale (TIS) using LMM. RESULTS: Anterior-posterior displacement of CoP (AP_CoP) (p = 0.011) and muscle activity of the GCL (p = 0.043) increased in the free condition of ankle dorsiflexion compared with that in the fixed condition. The FMAs (p = 0.004) and TIS (p = 0.008) demonstrated a positive relationship with AP_CoP. A positive relationship was also found between TIS and the percentage of medial forefoot loading time in the CoP (p < 0.001). CONCLUSIONS: For individuals with severe subacute hemiplegia, the ankle dorsiflexion induction in the KAFO, which did not impede the forward tilt of the shank, promotes anterior movement in the CoP and muscle activity of the GCL. This study suggests that adjusting the dorsiflexion mobility of the ankle joint in the KAFO according to improvement in physical function promotes loading of the CoP to the medial forefoot.

Use of the reliable change index to evaluate the effect of a multicomponent exercise program on physical functions.

AIMS: Using the reliable change index (RCI), we aimed to examine the effect of a multicomponent exercise program on the individual level. METHODS: Overall, 270 adults (mean age, 78 years) completed a multicomponent physical exercise program (strength, aerobic, gait, and balance) for 40 min, 1-2 times per week, continued up to 1 year at a daycare center. Effectiveness was assessed using grip, ankle, knee, and hip strength; Timed Up & Go (TUG); Berg Balance Scale (BBS); gait speed; and 6-min walking distance. These were measured at baseline and every 3 months thereafter. We calculated the RCI using the data between two-time points (baseline and at 3, 6, 9, or 12 months) in each participant and then calculated the mean RCI value across the participants. A paired t-test was also employed to evaluate the effect of the intervention as an average-based statistics. RESULTS: The highest mean RCI values were on ankle plantar-flexion strength, followed by gait speed, hip abduction strength, BBS, knee extensor strength, 6-min walk distance, grip strength, and finally TUG. Paired t-test also revealed significant improvement with moderate effect sizes for ankle plantar-flexion strength (0.504), gait speed (0.413), hip abduction strength (0.374), BBS (0.334), knee extensor strength (0.264), and 6-min walk distance (0.248). Significant but small effect size was seen on TUG (0.183). CONCLUSION: The RCI is a convenient method of comparing the effect between different assessments, especially at an individual level. This index can be applied to the use of personal feedback.

How to Decide the Number of Gait Cycles in Different Low-Pass Filters to Extract Motor Modules by Non-negative Matrix Factorization During Walking in Chronic Post-stroke Patients.

The motor modules during human walking are identified using non-negative matrix factorization (NNMF) from surface electromyography (EMG) signals. The extraction of motor modules in healthy participants is affected by the change in pre-processing of EMG signals, such as low-pass filters (LPFs); however, the effect of different pre-processing methods, such as the number of necessary gait cycles (GCs) in post-stroke patients with varying steps, remains unknown. We aimed to specify that the number of GCs influenced the motor modules extracted in the consideration of LPFs in post-stroke patients. In total, 10 chronic post-stroke patients walked at a self-selected speed on an overground walkway, while EMG signals were recorded from the eight muscles of paretic lower limb. To verify the number of GCs, five GC conditions were set, namely, 25 (reference condition), 20, 15, 10, and 5 gate cycles with three LPFs (4, 10, and 15 Hz). First, the number of modules, variability accounted for (VAF), and muscle weightings extracted by the NNMF algorithm were compared between the conditions. Next, a modified NNMF algorithm, in which the activation timing profiles among different GCs were unified, was performed to compare the muscle weightings more robustly between GCs. The number of motor modules was not significantly different, regardless of the GCs. The difference in VAF and muscle weightings in the different GCs decreased with the LPF of 4 Hz. Muscle weightings in 15 GCs or less were significantly different from those in 25 GCs using the modified NNMF. Therefore, we concluded that the variability extracted motor modules by different GCs was suppressed with lower LPFs; however, 20 GCs were needed for more representative extraction of motor modules during walking in post-stroke patients.

Longitudinal effects of physical exercise on health-related outcomes based on frailty status in community-dwelling older adults.

AIM: To clarify the difference in the longitudinal effects of physical exercise on health-related outcomes according to the baseline frailty status (frail or non-frail) in community-dwelling older adults. METHODS: Participants included 177 adults aged ≥65 years who carried out multicomponent physical exercises (strength, aerobic, gait and balance) for 40 min, one to three times per week, for 1 year at a day-care center. Bodyweight, comfortable walking speed, 6-min walking distance and Mini-Mental State Examination were measured at baseline and every 3 months. For longitudinal trend, we analyzed the change in scores from baseline for each outcome using the linear mixed effects model. Fixed effects included "group" (frail or non-frail), "time" (4 time points every 3 months, from 3 to 12 months) and "interaction between group and time." RESULTS: The effect sizes from baseline showed almost all positive values for each outcome. The linear mixed effects model showed significant effects on "interaction between group and time" in changes in bodyweight (P = 0.033), "group" in changes in walking speed (P = 0.013) and "time" in changes in the Mini-Mental State Examination (P < 0.001). Bodyweight showed a decreasing trend in the non-frail group after 3 months, unlike in the frail group. For walking speed, moderate effect sizes (d = 0.67-0.74) were sustained over time in the frail group, as did lesser effect sizes (d = 0.26-0.40) in the non-frail group. CONCLUSIONS: Exercise-based multicomponent interventions were effective for both groups. The longitudinal effects on walking speed and bodyweight were greater in the frail group. Geriatr Gerontol Int 2022; 22: 213-218.

Novel characterization of subjective visual vertical in patients with unilateral spatial neglect.

Visual vertical (VV), visually perceived direction of gravity, is widely measured to assess the vestibular function and visuospatial cognition. VV has been assessed by comparing orientation and variability of measured values separately between subject groups. However, changes in orientation and variability often differ in patients with unilateral spatial neglect (USN). Here, we developed a novel classification of VV that combines orientation and variability and characterized the effects of USN on VV. Forty-three subacute stroke patients with or without USN (USN+, n = 17; USN-, n = 26) and 33 age-matched controls were included in the study. In darkness, a luminous line, initially tilted at 30° either to the left or right, gradually rotated towards the vertical. The VV was defined as the deviation of the subjectively-perceived vertical from the true vertical. The new classification demonstrated that, while the majority of USN + patients (14/17) exhibited large variability, nine showed normal orientation and five showed greater contra-lesional deviation of orientation, suggesting different underlying mechanisms for orientation and variability. Further analyses revealed VV deviation to the initial tilt in all groups. However, the deviation in USN + was larger and more variable, indicating attentional disorders. Such characterization would contribute to individually specified clinical rehabilitation.

Relationship between vertical ground reaction force and muscle strength while climbing stairs after total hip arthroplasty.

BACKGROUND: Little is known about the relationship between vertical ground reaction force (vGRF) and muscle strength while climbing stairs after total hip arthroplasty (THA). METHODS: We investigated the relationship between muscle strength and vGRF during stair climbing in 21 women with THA. Differences in the time required to climb stairs and side-to-side differences in muscle strength and vGRF during climbing were examined at 6 and 12 months. The relationship between climbing time and vGRF variables and that between vGRF and muscle strength were analyzed using Spearman's rank correlation coefficient at 6 and 12 months. First peak force (Fz1) was defined as the peak vGRF at heel strike normalized by body weight. FINDINGS: Climbing time was related to the time to Fz1 at 6 and 12 months post-THA (r = 0.50-0.64). At 6 months, time to Fz1 was related to the strength of muscles involved in hip extension in the operated limb (r = -0.46). At 12 months, time to Fz1 was related to the strength of muscles responsible for knee extension in the operated limb (r = -0.45). INTERPRETATION: At 6 months, climbing stairs depended on muscle strength in the hip extensors. Conversely, at 12 months, the functional recovery of knee extensors was important for transferring weight upward while climbing stairs. Therefore, to improve the climbing function of patients with THA, it is important to not only focus on the recovery of muscle strength in the hip extensors but also improve muscle strength in the knee extensors.

Immediate Effect on Ground Reaction Forces Induced by Step Training Based on Discrete Skill during Gait in Poststroke Individuals: A Pilot Study.

METHODS: Twenty-two community-dwelling patients with chronic hemiplegia participated in this study. Eight participants performed only discrete-skill step training during the loading response phase, focusing on paretic hip extension movement (LR group). Another eight performed only discrete-skill step training during the preswing phase, focusing on paretic swing movement (PSw group). The remaining six were trained using both training methods, with at least 6 months in each group to washout the influence of previous training. Therefore, the final number of participants in each group was 14. The braking and propulsive forces of GRFs were measured during gait before and after 30 repetitions of the discrete-skill step training. RESULTS: Although both groups showed a significant increase in stride length, walking speed was increased only in the LR group. The PSw group showed an increase in braking forces of both sides without any change in propulsion. In the LR group, paretic braking impulse did not change, while nonparetic propulsion increased. CONCLUSION: The discrete-skill step training during loading response phase induced an increase in nonparetic propulsion, resulting in increased walking speed. This study provides a clear understanding of immediate effects of the discrete-skill step training in patients with chronic stroke and helps improve interventions in long-term rehabilitation.