Effects of Dancer-Specific Biomechanics on Adolescent Ballet Dancers' Posture En Pointe and Factors Related to Pointe Readiness: A Cross-Sectional Study.

OBJECTIVE: There are no universally accepted requirements or uniform protocols to determine when dancers can safely commence dancing en pointe (shod relevé). The purpose of this study was to examine dancer-specific biomechanics of adolescent pointe dancers and explore factors that may help determine pointe readiness. METHODS: Dancers (n=26; median age 14 yrs [IQR=13-16]) were stratified into two groups based on the ability to stand on the pointe shoe box as per a plumb line (Group 1: on the box; Group 2: not on the box) during parallel, shod relevé. Measurements included unshod weight-bearing range of motion (ROM) of ankle plantarflexion (PF) and first metatarsophalangeal (MTP) extension and shod posture assessment during first position elevé (rising into relevé with turned out, straight legs). Qualisys 3D motion capture and AMTITM force plates recorded dancers performing 10-15 repetitions of first position elevé. Comparison of three kinematic and three kinetic variables aimed to describe group differences during unshod and shod conditions. Wilcoxon signed-rank test assumed no difference between groups with a Bonferroni correction (p<0.0083). RESULTS: During unshod parallel relevé, ROM was different between groups for first MTP extension (deg; MedGroup1: 90°, IQR 80°-90°; MedGroup 2: 70°, IQR: 70°-80°, p<0.0001) but no statistical difference in ankle PF (deg; p=0.0098). There were no differences in C7 displacement (m; p=0.5055), ankle PF moment (p=0.1484), or hip mediolateral and anteroposterior moments (p=0.8785 and 0.8785, respectively) during shod first position relevé, indicating that both groups tend to engage the same dominant muscle groups (trunk extensors, ankle dorsiflexors, hip flexors, and hip abductors) during elevé. CONCLUSION: Dancers in Group 1 demonstrated greater first MTP extension during unshod relevé compared to dancers in Group 2. Weight-bearing ROM could be a valuable tool in predicting pointe readiness of adolescent ballet dancers.

Development and Earliest Validation of a Portable Device for Quantification of Hallux Extension Strength (QuHalEx).

Hallux strength is associated with sports performance and balance across the lifespan, and independently predicts falls in older adults. In rehabilitation, Medical Research Council (MRC) Manual Muscle Testing (MMT) is the clinical standard for hallux strength assessment, but subtle weakness and longitudinal changes in strength may go undetected. To address the need for research-grade yet clinically feasible options, we designed a new load cell device and testing protocol to Quantify Hallux Extension strength (QuHalEx). We aim to describe the device, protocol and initial validation. In benchtop testing, we used eight precision weights to apply known loads from 9.81 to 78.5 N. In healthy adults, we performed three maximal isometric tests for hallux extension and flexion on the right and left sides. We calculated the Intraclass Correlation Coefficient (ICC) with 95% confidence interval and descriptively compared our isometric force-time output to published parameters. QuHalEx benchtop absolute error ranged from 0.02 to 0.41 (mean 0.14) N. Benchtop and human intrasession output was repeatable (ICC 0.90-1.00, p < 0.001). Hallux strength in our sample (n = 38, age 33.5 ± 9.6 years, 53% female, 55% white) ranged from 23.1 to 82.0 N peak extension force and 32.0 to 142.4 N peak flexion, and differences of ~10 N (15%) between toes of the same MRC grade (5) suggest that QuHalEx is able to detect subtle weakness and interlimb asymmetries that are missed by MMT. Our results support ongoing QuHalEx validation and device refinement with a longer-term goal of widespread clinical and research application.

User Participatory Design of a Wearable Focal Vibration Device for Home-Based Stroke Rehabilitation.

Stroke often leads to the significant impairment of upper limb function and is associated with a decreased quality of life. Despite study results from several interventions for muscle activation and motor coordination, wide-scale adoption remains largely elusive due to under-doses and low user compliance and participation. Recent studies have shown that focal vibration has a greater potential to increase and coordinate muscle recruitment and build muscle strength and endurance. This form of treatment could widely benefit stroke survivors and therapists. Thus, this study aimed to design and develop a novel wearable focal vibration device for upper limb rehabilitation in stroke survivors. A user participatory design approach was used for the design and development. Five stroke survivors, three physical therapists, and two occupational therapists were recruited and participated. This pilot study may help to develop a novel sustainable wearable system providing vibration-based muscle activation for upper limb function rehabilitation. It may allow users to apply the prescribed vibratory stimuli in-home and/or in community settings. It may also allow therapists to monitor treatment usage and user performance and adjust the treatment doses based on progression.

The Impact of Cognition on Motor Learning and Skill Acquisition Using a Robot Intervention in Infants With Cerebral Palsy.

Background: Cerebral Palsy (CP) is a neurodevelopmental disorder that encompasses multiple neurological disorders that appear in infancy or early childhood and persist through the lifespan of the individual. Early interventions for infants with CP utilizing assisted-motion robotic devices have shown promising effects in rehabilitation of the motor function skills. The impact of cognitive function during motor learning and skill acquisition in infants using robotic technologies is unclear. Purpose: To assess the impact of cognitive function of infants with and without CP on their motor learning using the Self-Initiated Prone Progression Crawler (SIPPC) robot. Methods: Statistical analysis was conducted on the data obtained from a randomized control trial in which the movement learning strategies in infants with or at risk for CP was assessed during a 16-week SIPPC robot intervention. Cognitive function was measured by the Bayley scales of Infant and Toddler Development-Third edition (Bayley-III) and motor function was measured by the Movement Observation Coding Scheme (MOCS). The infants were categorized into three distinct groups based on their cognitive scores at baseline: "above average" (n1 = 11), "below average" (n2 = 10), and "average" (n3 = 26). Tri-weekly averages of the MOCS scores (observations at five time points) were used for the analyses. This study involved computing descriptive statistics, data visualization, repeated measures analysis of variances (rmANOVA), and survival analyses. Results: The descriptive statistics were calculated for the MOCS and Bayley III scores. The repeated measures ANOVAs revealed that there was a statistically significant effect of time (p < 0.0001) on scores of all subscales of the MOCS. A statistically significant effect of interaction between group and time (p < 0.05) was found in MOCS scores of subscales 1 and 2. The survival analyses indicated that infants in different cognition groups significantly differed (p < 0.0001) in their ability to achieve the crawling milestone within the 16-week intervention period. Conclusion: The findings in this study reveal the key movement strategies required to move the SIPPC robot, assessed by the MOCS, vary depending on the infants' cognition. The SIPPC robot is well-matched to cognitive ability of infants with CP. However, lower cognitive ability was related to delayed improvement in their motor skills.

Improvement of Gait after 4 Weeks of Wearable Focal Muscle Vibration Therapy for Individuals with Diabetic Peripheral Neuropathy.

People with diabetic peripheral neuropathy (DPN) experience lower quality of life caused by associated balance, posture, and gait impairments. While focal muscle vibration (FMV) has been associated with improvements in gait performance in individuals with neurological disorders, little is known about its effectiveness in patients with DPN. The purpose of this study was to investigate the effect of FMV on gait outcomes in patients with DPN. The authors randomized 23 participants into three FMV intervention groups depending upon the delivery of vibration. Participants applied wearable FMV to the bilateral quadriceps, gastrocnemius, and tibialis anterior, 10 min per muscle, three times per week over a four-week period. Spatiotemporal, kinematic, and kinetic gait parameters at baseline and post-intervention were calculated and analyzed. Gait speed, cadence, stride time, left and right stance time, duration of double limb support, and left and right knee flexor moments significantly improved after four weeks of FMV. Trends toward significant improvements were noted in maximum left and right knee flexion. Results indicate that FMV therapy was associated with improvements in gait parameters in individuals with DPN, warranting expanded study of FMV therapy for long-term gait performance improvement in these individuals.