Effect of dual-task interaction combining postural and visual perturbations on cortical activity and postural control ability.

Previous studies have suggested cortical involvement in postural control in humans by measuring cortical activities and conducting dual-task paradigms. In dual-task paradigms, task performance deteriorates and can be facilitated in specific dual-task settings. Theoretical frameworks explaining these dual-task interactions have been proposed and debated for decades. Therefore, we investigated postural control performance under different visual conditions using a virtual reality system, simultaneously measuring cortical activities with a functional near-infrared spectroscopy system. Twenty-four healthy participants were included in this study. Postural stability and cortical activities after perturbations were measured under several conditions consisting of postural and visual perturbations. The results showed that concurrent visual and postural perturbations could facilitate cortical activities in the supplementary motor area and superior parietal lobe. Additionally, visual distractors deteriorated postural control ability and cortical activation of the supplementary motor area. These findings supported the theoretical framework of the "Cross talk model", in which concurrent tasks using similar neural domains can facilitate these task performances. Furthermore, it indicated that the cortical resource capacity and domains activated for information processing should be considered in experiments involving dual-task paradigms and training.

Risk factors for hamstring strain injury in male college American football players -a preliminary prospective cohort study.

BACKGROUND: Given the frequency of hamstring strain injuries (HSI) among male college American football players, several studies have attempted to determine whether certain risk factors can predict their occurrence. However, no consensus on modifiable risk factors for HSIs in male college American football players has yet been reached to prevent these injuries. This study aimed to clarify risk factors for HSI prospectively in college male American football players. METHODS: A total of 78 male college American football players, whose positions were limited to skill positions, were medically assessed for potential risk factors of HSI. The preseason medical assessment included anthropometric measurements, joint laxity and flexibility, muscle flexibility, muscle strength, and balance ability. RESULTS: HSI occurred in a total of 25 thighs from 25 players (32.1%). Injured players had significantly lower hamstring flexibility (p = 0.02) and hamstring to quadriceps strength ratio (H/Q) (p = 0.047) compared to uninjured players. Additionally, injured players had significantly lower general joint laxity scores, especially for the total (p = 0.04), hip (p = 0.007), and elbow (p = 0.04) scores, compared to uninjured players. CONCLUSIONS: Lower hamstring flexibility, lower hamstring to quadriceps strength ratio, and lower general joint laxity score were identified as risk factors for HSI in male college American football players placed in skill positions. The muscle flexibility and H/Q ratio could be useful in preventing HSI in such players.

Body knowledge in children with spina bifida.

BACKGROUND: Patients with spina bifida suffer from motor paralysis and sensory disturbance, secondary deformation of the lower extremities, and development of decubitus ulcers. A deep understanding of one's body, such as identifying the names, functions, relationships, homology (e.g. upper and lower limbs) and relative position of body parts, may prevent secondary disorders. The awareness of the body and its characteristics in children with spina bifida has not been fully elucidated. This study aimed to investigate how children with spina bifida perceive their bodies, especially their paralyzed parts and related or homologous ones. METHODS: Participants included 36 children with spina bifida and 14 control children, aged 5-11 years. They were asked to draw self-portraits, and to answer questions about the names of body parts. The number of drawn body parts in the pictures and the correct response rates to the questions were quantified and compared between children with spina bifida and control children. RESULTS: Children with spina bifida drew fewer hands, legs, and feet than control children. In the verbal tests, children with spina bifida had a lower correct response rate than control children on questions concerning the upper limbs, hands, trunk, and feet. CONCLUSIONS: Children with spina bifida have diminished visuospatial and lexical-semantic body knowledge of the paralyzed parts and related organs.

Visual attention to their own paralytic limbs in children with spina bifida: Measurement of gaze direction using eye tracking.

BACKGROUND: Patients with spina bifida experience sensory and motor paralysis and complications in the form of deformation and skin problems of the lower limbs. Enhancing their awareness of the paralysed lesions could be helpful for these patients to prevent secondary disorders. This study sought to investigate to what extent children with spina bifida are visually aware of their body parts and, in particular, to their paralysed lesions. METHODS: Participants included children with spina bifida (n = 10) and typically developing control children (n = 10) between the ages of 5 and 11 years. All participants were shown still images of themselves on a monitor after which their gaze direction was measured using an eye tracker, with or without providing an instruction to direct their attention to their limbs. The gaze direction data were analyzed and compared between children with spina bifida and the control children. RESULTS: Children with spina bifida paid visual attention to their bodies in a manner similar to that of control children. Prompts to direct their attention to their limbs were effective in both groups; however, the degree of efficacy in children with spina bifida was inferior to that in control children. CONCLUSIONS: Promotion of visual awareness to their paralytic parts could be a reasonable and effective method for children with spina bifida to improve their understanding and recognition of their body and prevent associated skin problems.

Treatment approaches for congenital transverse limb deficiency: Data analysis from an epidemiological national survey in Japan.

BACKGROUND: Congenital limb deficiency is a rare anomaly that impairs limb function. Transverse deficiency accounts for approximately half of congenital limb deficiency cases. In Japan, there have been no detailed data of clinical features, especially treatment approaches, of this disorder. The present study aimed to investigate the status of treatment approaches of congenital transverse limb deficiency in Japan. METHODS: From the national epidemiological survey of congenital limb deficiency undertaken in Japan in 2016, all the data of 200 patients with congenital transverse limb deficiencies were extracted. These data were analysed to reveal the treatment approaches of congenital transverse limb deficiency and its basic clinical features. RESULTS: Surgical treatments and prosthetic or orthotic intervention had been implemented or planned for about one-quarter of patients, respectively. In the upper limb deficiencies, prosthetic or orthotic intervention was likely chosen in cases of deficiency at the metacarpal or proximal to metacarpal level. Surgical treatment was chosen only in cases of deficiency at the carpal or distal to carpal level. Although the number of patients with transverse lower limb deficiencies was small, prosthetic or orthotic intervention was likely chosen in proximal deficiencies, and surgical treatment was likely chosen in distal deficiencies. CONCLUSIONS: Herein, we revealed the status of treatment approaches for congenital transverse limb deficiency in Japan. Approximately half of the patients had no history of-and no plans for-surgical, prosthetic, or orthotic interventions. Further treatment advances may enable patients with congenital limb deficiencies to increase their participation in daily activities. STUDY DESIGN: Cross-sectional survey.

Impact of fracture characteristics and disease-specific complications on health-related quality of life in osteogenesis imperfecta.

Osteogenesis imperfecta (OI) is a connective tissue disease with bone fragility. Several studies have indicated that physical function in adult OI was correlated to the disease severity, but there have been no reports delineating the impact of the fracture characteristics and disease-specific complications on health-related quality of life (HRQoL). The purpose of this study is to clarify the factors impacted on HRQoL in adult OI patients. We conducted a cross-sectional study between July 2016 and March 2018 and sent a questionnaire regarding HRQoL using Short Form-36 (SF-36) to the OI patients at the age of 20 years or older who had a medical history of the investigators' institutions. The 40 patients completely answered the SF-36. Mental component summary and role/social component summary were unremarkable. Physical component summary (PCS) was significantly associated with z-score for height, teeth abnormality, and cardiopulmonary insufficiency (partial regression coefficient, 3.04, - 9.70, and - 11.35; p, < 0.001, 0.047, and 0.025, respectively). PCS was also significantly lower in the patients who had an initial fracture before the age of 2 years than those without occurrence of fractures until 2 years old (25.80 ± 17.15 versus 44.20 ± 16.54; p = 0.002), or those who had lower extremity fractures more than five times as compared with normal populations. Physical function was decreased in OI patients who had fractures before 2 years old, especially in lower extremity. Appropriate medical managements for cardiopulmonary insufficiency are required not only to maintain physical function but also to decrease mortality.

Effect of prostheses on children with congenital upper limb deficiencies.

BACKGROUND: Individual weaknesses in motor skills are a characteristic of children with congenital upper limb deficiencies. These weaknesses increase with age. In Japan, however, prosthetic prescription and subsequent rehabilitation approaches for children with upper limb deficiencies are insufficient and often delayed. This study aimed to elucidate whether rehabilitation approaches, including prostheses prescription and occupational therapy, improve these children's adaptive behaviors, especially their motor skills. METHODS: The study included nine children, aged 0-6 years, with unilateral transradial or transcarpal upper limb deficiencies. We measured their adaptive behaviors and motor skills at the beginning of prosthetic therapy and after 1.5 years, using the Vineland Adaptive Behavior Scales - Second Edition. RESULTS: The score for the motor skills domain was significantly lower than the median score of the domains at the beginning of prosthetic therapy. The motor skill weaknesses significantly improved after 1.5 years of prosthetic therapy. CONCLUSIONS: Although children with congenital upper limb deficiencies have individual weaknesses in their motor skill behavior, it was shown that these weaknesses can be improved through rehabilitation approaches, including occupational and prosthetic therapies. Issuing the appropriate prostheses and implementing the appropriate training to use the prostheses for congenital upper limb deficiencies are reasonable and meaningful interventions to improve quality of life.

Physical, Mental, and Social Problems of Adolescent and Adult Patients with Achondroplasia.

Patients with achondroplasia (ACH) require various medical interventions throughout the lifetime. Survey of health-related quality of life (HRQoL) in adult ACH patients is essential for the evaluation of treatment outcomes performed during childhood such as growth hormone administration and limb lengthening surgeries, but no study focused on the treatment strategy by analyzing HRQoL of ACH patients. The purpose of this study was to assess whether final height impacted on HRQoL and to evaluate what kinds of medical interventions were positively or negatively associated with HRQoL. We included 184 ACH patients (10-67 years old) who were registered in the patients' associations or who had a medical history of the investigators' institutions, and analyzed HRQoL by using Short Form-36 and patient demographics. Physical component summary (PCS) was significantly lower than the standard values in each age, especially in elderly populations, while mental component summary (MCS) was similar to the standard values. Role/social component summary was deteriorated only in elderly populations. The PCS was improved in the patients who had a height of 140 cm or taller (p < 0.001). The PCS and MCS were strongly associated with the past medical history of spine surgeries (p < 0.001 and p = 0.028, respectively). A treatment strategy would be planned to gain a final height of 140 cm or taller during childhood in combination with growth hormone administration and limb lengthening surgeries. Appropriate medical management for neurological complications of adult ACH patients is required to maintain physical and mental function.

Body knowledge in children with congenital lower limb deficiency.

BACKGROUND: In order to effectively improve motor function, a sound understanding of one's body - for example, relative spatial position, relationships, names and functions of body parts - is essential. The aim of this study was to explore how children with congenital lower limb deficiency (LLD) perceive their bodies, particularly their legs. METHODS: Six children with congenital LLD and 14 controls, aged 5-12 years, were recruited for this study. They drew self-portraits and answered questions about names of body parts. These body part-related questions consisted of a production test, in which an examiner pointed to body parts on each child and asked the child to name them, and a comprehension test, in which the examiner mentioned body parts and asked the child to point to them on their own body. RESULTS: No differences were found between the self-portraits of children with LLD and those of the control children. In the verbal tests, children with LLD responded correctly at lower rates to questions on body trunk, upper limbs, arms, hands and feet than the control children. CONCLUSION: Children with LLD have diminished lexical-semantic body knowledge of the upper limbs and feet compared with children without LLD.

Congenital limb deficiency in Japan: a cross-sectional nationwide survey on its epidemiology.

BACKGROUND: Congenital limb deficiency is a rare and intractable disease, which impairs both function and appearance of the limbs. To establish adequate medical care, it is necessary to reveal the actual conditions and problems associated with this disease. However, there have been no extensive epidemiological surveys in Japan addressing this disease. This is the first nationwide epidemiological survey of congenital limb deficiency in this country. METHODS: With the cooperation of epidemiology experts, we performed a two-stage nationwide survey to estimate the number of patients with congenital limb deficiency and reveal basic patient features. We targeted orthopaedic surgery, paediatric, and plastic surgery departments. Hospitals were categorized according to the institution type and the number of hospital beds; hospitals were randomly selected from these categories. We selected 2283 departments from a total 7825 departments throughout Japan. In this study, we defined congenital limb deficiency as partial or total absence of the limbs, proximal to the proximal interphalangeal joint of the fingers/lesser toes or interphalangeal joint of the thumb/great toe. We distributed the first survey querying the number of initial patient visits from January 2014 to December 2015. Targets of the second survey were departments that reported one or more initial patient visits in the first survey. RESULTS: In the first survey, 1767 departments responded (response rate: 77.4%). Among them, 161 departments reported one or more initial patient visits. We conducted the second survey among these 161 departments, of which 96 departments responded (response rate: 59.6%). The estimated number of initial visits by patients with congenital limb deficiency was 417 (95% confidence interval: 339-495) per year in 2014 and 2015. The estimated prevalence of congenital limb deficiency in Japan was 4.15 (95% confidence interval: 3.37-4.93) per 10,000 live births. The sex ratio was 1.40. Upper limbs were more affected than lower limbs. CONCLUSIONS: We revealed the estimated number of initial patient visits per year and birth prevalence of congenital limb deficiency in Japan. Our results will contribute to establishing the disease concept and grades of severity of congenital limb deficiency.

Histopathological Confirmation of Axonal Sprouting in Regenerative Peripheral Nerve Interface.

Symptomatic neuroma represents a debilitating complication after major limb amputation. The regenerative peripheral nerve interface (RPNI) has emerged as a reproducible and practical surgery aimed at mitigating the formation of painful neuroma. Although previous animal studies revealed axonal sprouting, elongation, and synaptogenesis of proximal nerve stump within the muscle graft in RPNI, there is a lack of reports confirming these physiological reactions at the histopathological level in human samples. This report presents a case of below-knee amputation with RPNI due to foot gangrene resulting from polyarteritis nodosa. Subsequently, an above-knee amputation was necessitated due to the exacerbation of polyarteritis nodosa, providing the opportunity for histopathological examination of the RPNI site. The examination revealed sprouting, elongation, and existence of neuromuscular junction of the tibial nerve within the grafted muscle. To the best of our knowledge, this is the first report demonstrating axonal sprouting, elongation, and possibility of synaptogenesis of the nerve stump within the grafted muscle in a human sample.

Lower hamstring to quadriceps muscle strength ratio and lower body weight as factors associated with noncontact anterior cruciate ligament injury in male American football players: A prospective cohort study.

Background: Previous studies have aimed to determine the use of certain risk factors in predicting the occurrence of noncontact anterior cruciate ligament (ACL) injuries. Unfortunately, evidence regarding noncontact ACL injuries in male American football players is limited. This prospective cohort study aimed to identify intrinsic risk factors for noncontact ACL injury among male American football players. Methods: This study evaluated 152 male American football players in Japan for potential noncontact ACL injury risk factors during a preseason medical assessment, including anthropometric, joint laxity, and flexibility, muscle flexibility, muscle strength, and balance measurements. A total of 25 variables were examined. Participants were monitored during each season for noncontact ACL injury, as diagnosed by physicians. Results: Noncontact ACL injuries occurred in 11 knees of 11 players (prevalence; 7.1 %). Injured players were significantly more likely to have lightweight (P = 0.049). No statistically significant between-group differences were found for any other variables. Participants with a lower hamstring to quadriceps (H/Q) ratio (P = 0.04) were more likely to sustain noncontact ACL injuries. Conclusion: Lower H/Q ratio and lower body weight were significantly associated with new-onset noncontact ACL injury in male American football players. These findings will help develop strategies to prevent noncontact ACL injuries in male American football players.

Factors Associated With a Lateral Ankle Sprain in Young Female Soccer Players: A Prospective Cohort Study.

Background: Previous studies have attempted to determine if certain risk factors can predict the occurrence of a lateral ankle sprain (LAS) in female soccer players. Unfortunately, there is limited evidence with regard to risk factors associated with an LAS in female soccer players. Purpose: To identify intrinsic risk factors for an LAS among young female soccer players. Study Design: Cohort study; Level of evidence, 2. Methods: Participants were 161 young female soccer players in Japan who were evaluated for LAS risk factors during a preseason medical assessment. The assessment included anthropometric, joint laxity, joint range of motion, muscle flexibility, muscle strength, and balance measurements. Each athlete's history of LASs was also collected. The participants were monitored during a single-yearseason for LASs, as diagnosed by physicians. Results: There were 26 instances of an LAS in 25 players (15.5%) during the season. Injured players were significantly more likely to have sustained a previous ankle sprain (P = .045) and demonstrated significantly worse balance than their peers without an LAS during the double- and single-leg balance tests (P = .008 for both). Athletes with lower hamstring-to-quadriceps muscle strength ratios were also significantly more likely to sustain an LAS (P = .02). Conclusion: Poor balance, a low hamstring-to-quadriceps ratio, and a history of ankle sprains were associated with an increased risk of LASs in young female soccer players in the current study. These findings may be useful for developing a program to prevent LASs in this population.

Motion Capture-based 3-dimensional Measurement of Range of Motion in Patients Undergoing Cervical Laminoplasty.

STUDY DESIGN: A prospective study. OBJECTIVE: To measure 3-dimensional cervical range of motion (ROM) by noninvasive optical tracking-based motion-capture technology in patients undergoing laminoplasty, and to elucidate the postoperative effects of laminoplasty on cervical mobility. SUMMARY OF BACKGROUND DATA: Cervical laminoplasty is a motion-sparing decompression surgery for degenerative cervical myelopathy. Unlike cervical laminectomy and fusion, the true postoperative impact of laminoplasty on neck motion has not been well studied. METHODS: Participants comprised 25 patients undergoing double-door cervical laminoplasty for degenerative cervical myelopathy in a single center. Maximum flexion/extension, left/right rotation, and left/right side bending were recorded using the motion-capture device preoperatively and 3 months postoperatively. ROMs in 3 orthogonal axes were calculated. Preoperative differences in C2-7 Cobb angles on lateral flexion/extension x-rays were also measured as the radiologic ROM to assess reliability. Preoperative and 1-year postoperative Japanese Orthopaedic Association score, Neck Disability Index [NDI], and Euro-QOL were recorded, and correlations with ROMs were assessed. RESULTS: Preoperative mean (±SD) ROMs for flexion/extension, rotation, and side bending were 90±17, 107±16, and 53±17 degrees, respectively. Although radiologic sagittal ROM measurement showed a smaller range than motion capture, averaging 36±13 degrees, a moderate to strong correlation between radiologic and motion capture values was observed (R=0.57, P=0.003). Preoperative NDI showed a negative correlation with coronal ROM (rho=-0.547, P=0.02). Postoperative ROM showed a significant reduction in rotation (95±16 degrees, P=0.002) but not in flexion/extension or side bending. CONCLUSIONS: Three-dimensional motion-capture analysis allowed reliable measurement of cervical ROM. Rotational ROM was significantly reduced after laminoplasty, showing that cervical kinematics are still significantly altered.

Relationship between degree of disability, usefulness of assistive devices, and daily use duration: an investigation in children with congenital upper limb deficiencies who use upper limb prostheses.

Upper limb prostheses can help children with congenital upper limb deficiencies (ULDs) perform activities of daily living. Although the degree of disability and prosthesis usefulness may be related to becoming accustomed to wearing a prosthesis, these relationships have not been confirmed. This study was aimed at investigating the relationship between motor function, the usefulness of prostheses in everyday activities, and daily duration of prosthesis use in children with congenital ULDs. Eleven children with congenital transcarpal or transradial ULDs and their caregivers participated in this study. The caregivers were asked to complete a questionnaire concerning their children's everyday activities and the daily duration of prosthesis wearing. The adaptive behavior scale was used to measure motor function prior to intervention. Correlations analyses revealed no significant correlation between the children's adaptive behavior, including motor skills before intervention, and daily duration of prosthesis wearing, but revealed a positive correlation between the number of activities that the children performed more effectively with their prostheses and the daily use duration. To ensure that children with congenital ULDs become accustomed to wearing their prostheses, the prostheses should meet the requirements of everyday activities.

Intellectual Characteristics in Children With Congenital Unilateral Upper Limb Deficiencies.

Introduction Some children with motor disabilities show low cognitive levels. However, the influence of motor disabilities on children's intelligence remains to be fully elucidated. This study aimed to clarify the intellectual characteristics of children with upper limb deficiencies and the influence of upper limb impairments on intelligence. Methods The participants were 10 children from four to six years of age with congenital unilateral transradial or transcarpal limb deficiencies who received prosthetic interventions. The children's intelligence and adaptive behaviors, including motor skills, were examined using the Wechsler Preschool and Primary Scale of Intelligence and the Vineland Adaptive Behavior Scale, respectively. Results There were no significant characteristics or discrepancies in cognitive level in children with upper limb deficiencies. The Adaptive Behavior Composite Score of the Vineland Adaptive Behavior Scale was significantly positively correlated with the Full-Scale Intelligence Quotient of the Wechsler Preschool and Primary Scale of Intelligence. Conclusions The children with congenital limb deficiencies showed average cognitive levels. Expansion of adaptive behaviors, including appropriate complementation of disabilities, may promote intellectual development in children with motor disabilities.

The identification of transcriptional targets of Ascl1 in oligodendrocyte development.

The basic helix-loop-helix (bHLH) transcription factor Ascl1 plays crucial roles in both oligodendrocyte development and neuronal development; however, the molecular target of Ascl1 in oligodendrocyte progenitor cells (OPCs) remains elusive. To identify the downstream targets of Ascl1 in OPCs, we performed gene expression microarray analysis and identified Hes5 as a putative downstream target of Ascl1. In vivo analysis revealed that Ascl1 and Hes5 were coexpressed in early developmental oligodendrocytes in both the telencephalon and the ventral spinal cord. We also found that Hes5 expression was reduced in the OPCs of Ascl1 mutant mice. Furthermore, we demonstrated that Ascl1 directly binds to an E-box region within the Hes5 promoter and regulates Hes5 expression at the transcriptional level. Taken together, these in vivo and in vitro data suggest that Ascl1 induces Hes5 expression in a cell-autonomous manner. Considering the previously known function of Hes5 as a repressor of Ascl1, our data indicate that Hes5 is involved in the negative feedback regulation of Ascl1.

Inconvenience and adaptation in Japanese adult achondroplasia and hypochondroplasia: A cross-sectional study.

The health-related quality of life is reduced in patients with achondroplasia (ACH) and hypochondroplasia (HCH); however, the detailed inconveniences in the daily living and individual adaptations have not been elucidated. This study aimed to evaluate the inconvenience and adaptation in patients with ACH/HCH. A cross-sectional study was conducted in patients with ACH/HCH aged 20 yr or older. Questionnaires were sent to 567 patients (described 86) with a medical history at the co-authors' institutions or who were registered at the patients' association with ACH in Japan. The questionnaire included a free description format for the inconveniences and adaptations in daily living; a content analysis was performed. The recorded inconveniences included 148 physical, 84 mental, and 52 social problems. Patients who underwent spine surgery had significantly more recorded physical problems than those who did not (p < 0.05). Pain and numbness were significantly higher in patients aged ≥ 50 yr (p < 0.05). The 160 and 1 adaptations were for physical and social problems, respectively. No patient adaptation was found for mental health problems. Individual adaptations by ACH/HCH patients can improve only some aspects of physical and social problems. Multilateral social support is needed to resolve patients' issues.

Dynamic Postural Stability Is Decreased During the Single-Leg Drop Landing Task in Male Collegiate Soccer Players With Chronic Ankle Instability.

Background: Chronic ankle instability (CAI) is commonly encountered in soccer players. The feelings of instability and anxiety caused by CAI can lead to poor performance, such as difficulty in sharp change of direction during soccer play. The single-leg drop landing (SLDL) task is often used to evaluate dynamic postural stability. Purpose/Hypothesis: The purpose of this study was to clarify whether dynamic stability measured during SLDL is altered in male collegiate soccer players with CAI. The hypothesis was that athletes with CAI would show poor dynamic postural stability. Study Design: Controlled laboratory study. Methods: A total of 103 male collegiate soccer players were recruited, and their limbs were classified based on the new international CAI criteria. All players performed three 5-second SLDL trials on a force plate. The main outcome measures included time to stabilization of the horizontal ground-reaction force (GRF); peak GRF in the vertical, horizontal, and sagittal directions; and trajectory length of the center of pressure during SLDL. Results: Data from 59 CAI limbs and 147 non-CAI limbs were collected in this study. Time to stabilization of horizontal GRF was significantly longer in the CAI limbs (P < .001), and the peak GRFs in all directions were significantly lower in the CAI limbs (vertical, P < .001; horizontal, P < .001; sagittal, P = .001). Additionally, the trajectory length of the center of pressure was significantly greater in the CAI limbs (P = .004). Conclusion: Soccer players with CAI had decreased dynamic postural stability that led them to land softly when performing the SLDL task. Measurement of dynamic postural stability may be useful in the evaluation of CAI. Clinical Relevance: Our findings may be useful for strategies of daily training or as an evaluation tool.

Kinematic Differences Between the Dominant and Nondominant Legs During a Single-Leg Drop Vertical Jump in Female Soccer Players.

BACKGROUND: In soccer, the roles of the dominant (kicking) and nondominant (supporting) legs are different. The kinematic differences between the actions of the dominant and nondominant legs in female soccer players are not clear. PURPOSE: To clarify the kinematic differences between dominant and nondominant legs during a single-leg drop vertical jump (DVJ) in female soccer players. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 64 female high school and college soccer players were included in this study. Participants performed a single-leg DVJ test utilizing video motion capture with artificial intelligence during the preseason period. This study assessed the knee flexion angles, knee valgus angles, hip flexion angles, and lower leg anterior inclination angle at 3 time points (initial contact, maximum flexion of the knee, and toe-off) and compared them between the dominant and nondominant legs. These angles were calculated from motion capture data and analyzed in 3 dimensions. A paired t test was used to analyze the differences between legs, and the significance level was set at P < .05. RESULTS: The knee valgus angle at initial contact was greater in the nondominant leg (mean ± SD, 0.8°± 5.2°) than the dominant leg (-0.9°± 4.9°) (P < .01). There were no differences between legs for any other angles at any of the time points. CONCLUSION: The kinematics of the dominant and nondominant legs of female soccer players in a single-leg DVJ differ in knee valgus angle. CLINICAL RELEVANCE: Leg dominance is associated with the risk of sports injuries. Kinematic differences between the dominant and nondominant legs may be a noteworthy factor in elucidating the mechanisms and risk of sports injury associated with leg dominance.