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The current study aimed to examine (a) whether the dominant leg (DL) was associated with the contralateral side of functional scoliosis and (b) if any of the postural asymmetries' evaluation variables may be a reliable predictor of the functional scoliosis development in young male soccer players. Six hundred-nine (n = 609) male soccer players (age: 10.8 ± 2.7 years; height: 147 ± 17 cm; weight: 43.4 ± 14.6 kg; DL: Right 81.6%, Left 14%, Both 4.4%) participated in this study. The spinal asymmetries evaluation included thoracic kyphosis, lumbar lordosis, truncal rotation, shoulders alignment from posterior view, anterior and posterior pelvic tilt, anterior superior iliac spine (ASIS), hamstring tightness, and lower extremities discrepancy. A significant association was observed between the DL and the truncal rotation side: χ2(4) = 30.84, p = 0.001, V = 0.16. Participants with longer left legs were likelier to present a spinal asymmetry (OR = 1.18). The participants with higher left shoulders were 2.13 times more likely to have spinal asymmetry than the participants with normal shoulders level. Participants with left ASIS higher were 3.08 times more likely to present asymmetry than those with normally aligned ASIS levels. There was also a significant association between the DL and the side of truncal rotation: χ2(2) = 13.30, p = 0.001, V = 0.449. Logistic regression analysis for the functional scoliotic group and truncal rotation side demonstrated that the taller participants and participants with shorter right legs were more likely to have asymmetry on the left side (OR = 1.29, OR = 0.32). Participants with greater right hamstring stiffness were likelier to have a truncal rotation on the right side (OR = 0.93). Participants with higher left shoulders were 0.20 times less likely to have a truncal rotation on the left side than the participants with normal shoulders level. In conclusion, leg dominance in children and in youth soccer players may be a factor causing truncal rotation on the contralateral side. Additional causes, such as leg length discrepancy and pelvic tilt, may progressively lead to functional scoliosis.

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Daily living activities present a diverse array of task and environmental constraints, highlighting the critical role of adapting gait initiation (GI) for an individual's quality of life. This study investigated the effects of GI directions, obstacle negotiation, and leg dominance on anticipatory postural adjustments and stepping kinematics. Fourteen active, young, healthy individuals participated in GI across 4 directions-forward, medial 45°, lateral 45°, and lateral 90°-with variations in obstacle presence and leg dominance. Results revealed a consistent decreasing trend in maximum center of pressure displacement, anticipatory postural adjustment duration, step distance, and swing leg velocity with lateral shifts in GI directions, yet the step duration and swing leg heel trajectory were not affected by GI directions except in lateral 90° GI. Center of pressure displacements were intricately scaled to directional propulsive forces generation, and the stepping kinematics were influenced by the directional modifications in movements. With obstacles, modifications in anticipatory postural adjustment metrics and stepping kinematics reflected the obstacle clearance movements. The dominant leg GI exhibited longer step durations and greater movement variability in medial 45° GI. The current investigation of GI factors expands our existing understanding of GI dynamics and offers valuable insights applicable to fall prevention and gait rehabilitation strategies.

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Objective: This study was conducted to see whether those who had anterior cruciate ligament (ACL) reconstructions on their dominant legs performed better than those who had them on their nondominant legs 1-10 years after the surgery. Materials and Methods: An examination of people who sustained injuries to their dominant (n = 25) and nondominant (n = 25) legs between 1 and 10 years after ACL repair was undertaken in a cross-sectional research with 50 people aged 20-38. Everyone takes the fear avoidance belief questionnaire for physical activity (FABQ-PA), the lower extremity functional scale (LEFS), and the anterior cruciate ligament return to sport after injury (ACL-RSI) survey. Results: There was no statistically significant difference between the groups on the ACL-RSI, LEFS, and FABQ-PA (U = 254, P = 0.26; U = 314.4, P = 0.95; and U = 279.4, P = 0.53 correspondingly). Conclusion: Functional performance and patient mental health should be evaluated 1-10 years after ACL surgery. However, there is no correlation between which leg was the dominant one and the results. As a result, it has been shown that both dominant and nondominant leg injuries heal similarly over time. Future studies should examine additional variables that affect healing and return-to-sport results to improve rehabilitation and optimize long-term functional outcomes for individuals after ACL repair.

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Previous research has documented brain plasticity after an anterior cruciate ligament (ACL) tear and suggests that these neural adaptations contribute to poorer motor control. Since both brain hemispheres show adaptations, we hypothesized that reduced dynamic stability occurs not only in the injured, but also the contralateral, uninjured leg. Further, given brain hemispheric specialization's impact on motor coordination, we hypothesized the need to consider the injury side. A total of 41 female athletes and 18 controls performed single-leg jump-landings. Dynamic postural stability was measured as time-to-stabilization (TTS). We found reduced medio-lateral dynamic stability for the ACL injured leg (p = 0.006) with a similar trend for the contralateral leg (p = 0.050) compared to the control group. However, when distinguishing between injuries to the dominant and non-dominant legs, we found increased medio-lateral TTS only if the injury had occurred on the dominant side where landings on injured (p = 0.006) and contralateral (p = 0.036) legs required increased TTS. Assessments of dynamic stability, e.g., in the context of return-to-sport, should consider the injury side and compare results not only between the injured and the contralateral leg, but also to uninjured controls. Future research should not pool data from the dominant-leg ACL with non-dominant-leg ACL injuries when assessing post-injury motor performance.

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PURPOSE: Balance is an important performance aspect of all athletes. The aim of this study was to compare static and dynamic balance in soccer players in different positions. METHODS: Forty youth and young adult professional soccer players were divided into four groups according to their playing positions: goalkeepers (GK), defenders (DF), midfielders (MF) and forwards (FW) (10 per position). Static and dynamic balance assessed on the dominant and non-dominant legs were measured using a force platform for 30s (static one-leg stand), and "Y Balance Test" (dynamic balance). RESULTS: GK exhibited greater ML static balance (less ML sway) compared with other players (p < 0.02-0.001). Moreover, results demonstrated better GK dynamic balance compared to DF and FW (p < 0.04-0.006). MF showed better dynamic balance than DF and FW (p < 0.019-0.007) and lower dynamic balance scores were found among DF and FW (p < 0.05). CONCLUSION: In conclusion, these results affirm position-specific balance performance with greater static and dynamic balance of GK and dynamic balance with MF. It is suggested that evaluation of balance and postural control performance should be considered a relevant part of the position-specific functional evaluation of soccer players.

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Background: Explosive and fast body movements, sprints, jumps and quick changes of direction, which are characteristic of the football training, place considerable strain on the hamstring muscles. Due to the high occurrence of hamstring injuries, new preventive strategies are required that focus on high-velocity training. The purpose was to assess the effectiveness of high-velocity elastic-band training in reducing the occurrence of hamstring injuries in football players. Methods: Male football players from 15 teams (n = 319) playing in national competitions participated in this study. The players were involved in a 5-week exercise period in either the intervention group (INT) or the control group (CON), with a follow-up period of ∼4 months where hamstring injuries and exposure time were recorded. The INT group had two to three sessions per week of elastic-band training with low-load, high-velocity leg curls while lying prone; the CON group performed self-paced football-specific drills. Results: The incidence rate of hamstring injuries was 6.5% in the INT group (8 out of 123 players) and 9.2% in the CON group (18 out of 196 players). Although the INT group showed almost 1/3 reduction in hamstring injury incidence compared to the CON group, the difference was not statistically significant (p > 0.05). Moreover, no differences (p > 0.05, odds ratio [OR] = trivial-to-small) in distribution between the groups were found in hamstring injury characteristics (leg dominance and mechanism) except for the distribution of injuries that occurred during matches or training (p = 0.036; OR = 6.14, moderate). Conclusion: The program of high-velocity elastic-band training did not prove to be effective in preventing hamstring muscle injuries in football players despite displaying some positive indications that could be considering when creating injury prevention programs.

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BACKGROUND: Detecting and classifying factors that contribute to age-related balance decline are essential for targeted interventions. Dynamic postural tests that challenge neuromuscular balance control are important to detect subtle deficits that affect functional balance in healthy aging. RESEARCH QUESTION: How does healthy aging affect specific components of dynamic postural control as measured by the simplified Star Excursion Balance Test (SEBT)? METHODS: Twenty healthy younger (18-39 years) and twenty healthy older (58-74 years) adults performed the standardized simplified SEBT, which involved standing on one leg and reaching the contralateral leg as far as possible in the anterior, posteromedial, and posterolateral directions. Optical motion capture was used to quantify the maximum reach distance normalized by body height (%H) for three repeated trials in each direction per leg. Linear mixed effects models and pairwise comparisons of estimated marginal means were used to assess differences (p < 0.05) in normalized maximum reach distance by age group, reach direction, and leg dominance. Intersubject and intrasubject variability were also assessed by age group using coefficients of variation (CV). RESULTS: Healthy older adults had less dynamic postural control compared to younger adults, with shorter reach distances in the anterior (7.9 %), posteromedial (15.8 %), and posterolateral (30.0 %) directions (p < 0.05). Leg dominance and sex did not significantly affect SEBT score for either age group (p > 0.05). Low intrasubject variability (CV<0.25 %) was found for repeated trials in both the older and younger participants. Therefore, the comparatively higher intersubject variability (Range CV=8-25 %) was mostly attributed to differences in SEBT performance across participants. SIGNIFICANCE: Quantifying dynamic postural control in healthy older adults in a clinical setting is important for early detection of balance decline and guiding targeted and effective treatment. These results support that the simplified SEBT is more challenging for healthy older adults, who may benefit from dynamic postural training to mitigate age-related decline.

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We examined the effects of side-dominance on the laterality of standing stability using ground reaction force, motion capture (MoCap), and EMG data in healthy young adults. We recruited participants with strong right (n = 15) and left (n = 9) hand and leg dominance (side-dominance). They stood on one or two legs on a pair of synchronized force platforms for 50 s with 60 s rest between three randomized stance trials. In addition to 23 CoP-related variables, we also computed six MoCap variables representing each lower-limb joint motion time series. Moreover, 39 time- and frequency-domain features of EMG data from five muscles in three muscle groups were analyzed. Data from the multitude of biosignals converged and revealed concordant patterns: no differences occurred between left- and right-side dominant participants in kinetic, kinematic, or EMG outcomes during bipedal stance. Regarding single leg stance, larger knee but lower ankle joint kinematic values appeared in left vs right-sided participants during non-dominant stance. Left-vs right-sided participants also had lower medial gastrocnemius EMG activation during non-dominant stance. While right-side dominant participants always produced larger values for kinematic data of ankle joint and medial gastrocnemius EMG activation during non-dominant vs dominant unilateral stance, this pattern was the opposite for left-sided participants, showing larger values when standing on their dominant vs non-dominant leg, i.e., participants had a more stable balance when standing on their right leg. Our results suggest that side-dominance affects biomechanical and neuromuscular control strategies during unilateral standing.

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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.

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Side-to-side asymmetry of lower extremities may influence the risk of injury associated with drop jump. Moreover, drop heights using relative height across individuals based on respective jumping abilities could better explain lower-extremity loading impact for different genders. The purpose of the current study was to evaluate the sex differences of impact forces and asymmetry during the landing phase of drop-jump tasks using drop heights, set according to participants' maximum jumping height. Ten male and ten female athletes performed drop-jump tasks on two force plates, and ground reaction force data were collected. Both feet needed to land entirely on the dedicated force plates as simultaneously as possible. Ground reaction forces and asymmetry between legs were calculated for jumps from 100%, 130%, and 160% of each participant's maximum jumping height. Females landed with greater asymmetry at time of contact initiation and time of peak impact force and had more asymmetrical peak impact force than males. Greater values and shorter time after ground contact of peak impact force were found when the drop height increased to 160% of maximum jumping ability as compared to 100% and 130%. Females exhibited greater asymmetry than males during drop jumps from relative heights, which may relate to the higher risk of anterior cruciate ligament injury among females. Greater sex disparity was evident in impact force asymmetry than in the magnitude of peak impact force; therefore, it may be a more appropriate field-screening test for risk of anterior cruciate ligament injury.

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BACKGROUND: There has not been an investigation to determine whether leg dominance affects the recovery of quadriceps and hamstring strength, muscle reaction time (acceleration time, AT), and postural stability after anterior cruciate ligament (ACL) reconstruction in recreational-level athletic patients. METHODS: A total of 100 patients with isolated ACL injuries (58 patients had dominant leg injuries; 42 patients had non-dominant leg injuries) participated. All patients received an anatomical single-bundle ACL reconstruction using an auto-hamstring tendon graft without preoperative rehabilitation. Leg dominance was defined as the kicking leg. The quadriceps and hamstring strength, AT, and postural stability (overall stability index (OSI)) of both legs were assessed at three different time points (preoperative, 6 months, 12 months), using an isokinetic dynamometer and postural stabilometry system. RESULTS: All patients in both groups showed gradual improvement in quadriceps and hamstring muscle strength in the operated legs up to 1 year postoperatively. However, the mean value of quadriceps strength was lower in the operated non-dominant leg than the operated dominant leg 6 months postoperatively (P = 0.048). The AT and OSI of the operated legs in both groups recovered significantly 6 months postoperatively compared with their preoperative values; however, the AT and OSI values after 6 and 12 months were similar. CONCLUSION: Quadriceps strength of the operated non-dominant leg was lower than that of the operated dominant leg 6 months postoperatively; however, the strength of the quadriceps and hamstring muscles was not different after 12 months between the operated dominant and non-dominant legs. Clinicians and physical therapists should consider these results during early rehabilitation and identify effective protocols to enhance quadriceps strength, especially in patients with non-dominant leg injuries.

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BACKGROUND: The straight leg raise test (SLR) is one of the most performed physical tests for mechanosensitivity and impairment of the nervous system. According to the anatomy of the tibial nerve, ankle dorsiflexion and eversion movements could be used to perform the tibial neurodynamic test (TNT). To date, no study has documented the normal responses of the TNT. OBJECTIVE: To document normal responses of the TNT in asymptomatic individuals and to investigate influences from sex and leg dominance. METHODS: A cross-sectional study with 44 asymptomatic volunteer subjects, a total of 88 lower limbs, was carried out. The range of motion (ROM), quality, and distribution of sensory responses were recorded. The hip flexion ROM was measured when subjects reported an intensity of their symptoms of 2/10 (P1) and 8/10 (P2). RESULTS: The mean ROM for hip flexion at P1 was 44.22 ± 13.13∘ and 66.73 ± 14.30∘ at P2. Hip flexion was significantly greater at P2 than P1 (p< 0.001). However, it was not different between sex or limbs (p> 0.05). The descriptor of the quality of sensory responses most often used by participants was stretching (88.6% and 87.5% for P1 and P2, respectively) in the popliteal fossa and posterior calf. CONCLUSIONS: This study describes the sensory responses of asymptomatic subjects resulting from the TNT. Our findings indicate that TNT responses are independent of the influence of sex or leg dominance.

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Leg dominance reflects the preferential use of one leg over another and is typically attributed to asymmetries in the neural circuitry. Detecting leg dominance effects on motor behavior, particularly during balancing exercises, has proven difficult. The current study applied a principal component analysis (PCA) on kinematic data, to assess bilateral asymmetry on the coordinative structure (hypothesis H1) or on the control characteristics of specific movement components (hypothesis H2). Marker-based motion tracking was performed on 26 healthy adults (aged 25.3 ± 4.1 years), who stood unipedally on a multiaxial unstable board, in a randomized order, on their dominant and non-dominant leg. Leg dominance was defined as the kicking leg. PCA was performed to determine patterns of correlated segment movements ("principal movements" PMks). The control of each PMk was characterized by assessing its acceleration (second-time derivative). Results were inconclusive regarding a leg-dominance effect on the coordinative structure of balancing movements (H1 inconclusive); however, different control (p = 0.005) was observed in PM3, representing a diagonal plane movement component (H2 was supported). These findings supported that leg dominance effects should be considered when assessing or training lower-limb neuromuscular control and suggest that specific attention should be given to diagonal plane movements.

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We investigated whether bilateral lower-limb control and leg dominance affect force control ability in 15 healthy young adults (9 males and 6 females, age =26.8 ± 4.1 years). Participants performed isometric ankle dorsiflexion force control tasks, matching a visual target (10% of maximal effort) as quickly and precisely as possible in ballistic and tonic tasks. Performance was evaluated using force error, force steadiness, amount of muscle activity of the tibialis anterior, and response time characteristics. Results showed no significant effects of leg dominance during both ballistic and tonic tasks, while bilateral condition resulted in significantly larger error, less force steadiness, compared to unilateral condition, and only during the tonic task. Consequently, bilateral control, specifically in tasks utilizing feedback control (i.e., tonic task) might affect force control ability, possibly because of the interhemispheric inhibition to meet bilateral task complexity and integrate afferent bilateral sensory information from both right and left legs.

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BACKGROUND: Neuromuscular imbalance will lead to loading asymmetry in sporting activities. This asymmetry is related to leg dominance, which has been associated with increased risk of anterior cruciate ligament (ACL) injury. Therefore, potential biomechanical differences between legs are important. However, little attention has been paid to the biomechanical details of leg dominance. The purpose of the present study was to clarify the relationship between leg dominance and knee biomechanics in females with different activity level during dynamic athletic tasks. METHODS: A total of 23 female collegiate (mean age = 19.6 ± 1.4 years, mean body mass index = 21.5 ± 0.9) and 19 recreational athletes (mean age = 20.7 ± 1.1 years, mean body mass index = 20.5 ± 1.7) were enrolled. Tegner activity scores of the collegiate and recreational athletes were 9 and 7, respectively. Knee kinematic and kinetic asymmetries between the dominant (DL) and non-dominant (NDL) legs during the landing phase of drop vertical jump (DVJ) were assessed using three-dimensional motion analysis in collegiate and recreational athletes separately. Statistical comparison was done using two-tailed paired t test between DL and NDL in each athlete. RESULTS: The peak knee abduction angle was significantly larger on the DL than on the NDL in collegiate athletes. Knee abduction angle at initial contact (IC), peak knee abduction angle, knee internal rotation angle at IC, and peak knee internal rotation angle were significantly larger on the NDL than on the DL in recreational athletes. Moreover, peak knee abduction moment within 40 ms from IC was larger on the NDL than on the DL in recreational athletes, while the moment was not significantly different in collegiate athletes. CONCLUSIONS: From the present study, the relationship between leg dominance and knee biomechanics was totally different in females with different activity level. Specifically, asymmetry of the knee abduction angle between limbs was opposite between female recreational and collegiate athletes. According to previous literatures, abduction and internal rotation angles as well as abduction moment were key issues for mechanism of non-contact ACL injury. Therefore, the NDL in female recreational athletes was associated with increased risk of ACL injury.

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Leg dominance has been reported as one potential risk factor for lower-limb injuries in recreational downhill skiers. The current study proposed and tested two possible mechanisms for a leg dominance effect on skiing injuries-imbalance of the knee muscle strength and bilateral asymmetry in sensorimotor control. We hypothesized that the knee muscle strength (Hypothesis 1; H1) or postural control (Hypothesis 2; H2) would be affected by leg dominance. Fifteen well-experienced recreational downhill skiers (aged 24.3 ± 3.2 years) participated in this study. Isometric knee flexor/extensor muscle strength was tested using a dynamometer. Postural control was explored by using a kinematic principal component analysis (PCA) to determine the coordination structure and control of three-dimensional unipedal balancing movements while wearing ski equipment on firm and soft standing surfaces. Only H2 was supported when balancing on the firm surface, revealing that when shifting body weight over the nondominant leg, skiers significantly changed the coordination structure (p < 0.006) and the control (p < 0.004) of the lifted-leg movements. Based on the current findings, bilateral asymmetry in sensorimotor control rather than asymmetry in strength seems a more likely mechanism for the previously reported effect of leg dominance on lower-limb injury risk in recreational downhill skiers.

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OBJECTIVES: This study was undertaken to determine the role of computed tomography (CT)-based methodology to segment the SI joint and quantify the metabolic activity using positron emission tomography (PET). We measured tracer uptake in the right and left SI joints independently to look for differences between the two sides. Further, we correlated tracer uptake with BMI and studied the inter-observer variation with regard to estimated tracer uptake in the SI joints. METHODS: In this retrospective study, a total of 103 subjects (48 females, 55 males) from the CAMONA study database collected 2012-2016 at Odense University Hospital in Denmark were included. Mean age was 48±14.59 years, mean BMI was 26.68±4.31 kg/m2. The SI joints were segmented on fused PET/CT images using a 3D growing algorithm with adjustable upper and lower Hounsfield Units (HU) thresholds. The metabolic activities on the two sides were correlated with BMI. RESULTS: For FDG, we found a higher average SUVmean on the right side (right: 1.3±0.33, left: 1.13±0.30; <0.0001). Similarly, for NaF, the uptake was higher on the right side (right: 5.9±1.29, left: 4.27±1.23; <0.0001). Positive correlations were present between BMI and FDG uptake (P<0.01) as well as NaF uptake (P<0.01). CONCLUSION: The PET-based molecular imaging probes along with the CT-based segmentation techniques revealed a significant difference in the metabolic activity between the two SI joints with higher inflammation and reactive bone formation on the right side. FDG and NaF uptakes correlated significantly and positively with BMI.

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BACKGROUND: Neurodynamic tests (NDTs) have shown to be useful in evaluating neural tissue involvement. Peroneal nerve reaches high importance in ankle injuries. However, up to date, no study has documented the normal responses for this nerve. OBJECTIVES: The objective of this study was to document normal responses of the peroneal neurodynamic test (NDTPER) in asymptomatic subjects. Differences in sensory response depending on sex and leg dominance were also examined. DESIGN: A cross-sectional study was designed. METHOD: Forty-four asymptomatic subjects with a total of 88 lower limbs were tested. The range of motion (ROM) at the point of first appearance of symptoms (S1) and the point of symptoms tolerance (S2), quality and distribution of sensory responses were recorded. RESULTS: Hip flexion was significantly higher at S2 than S1 (mean difference, 27.22°; 95% CI: 25.29°, 29.14°; p < 0.001). However, it was not different between sex, nor dominance (p > 0.05). The descriptor of the quality of sensory responses more often used by subjects was stretching (90.9%) in the external foot (74.6%). CONCLUSIONS: This study provides the normal hip flexion angle and quality and distribution of sensory responses to the NDTPER in asymptomatic subjects. Responses were independent of the influence of sex or leg dominance.

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Background and objectives: Although tendon elasticity by elastography is useful for diagnosing tendon disorders and planning rehabilitation regimens of the tendon, there are few reports on the quadriceps tendon. Moreover, relationships between the quadriceps tendon elasticity and knee angle have not been investigated. The purpose of this study was to clarify the relationship between quadriceps tendon elasticity and knee flexion angle in young healthy adults using elastography, and to investigate the difference in elasticity by sex and leg dominance. Materials and Methods: A total of 40 knees in 20 young healthy adults were included in this study (age: 25.5 (23.3⁻27.5) years). At knee flexion of 30°, 60°, and 90°, quadriceps tendon elasticity was measured using ShearWave™ Elastography during the ultrasound examination. Results: There were significant differences in the elasticity between all angles (p < 0.001). Elasticity was increased more at 60° than at 30° and at 90° than at 60°. Elasticity in men was higher than that in women at 60° (p = 0.029). There were no differences (p = 0.798) in elasticity at each angle between the dominant and non-dominant legs. Conclusions: The quadriceps tendon elasticity increased according to the knee flexion angle in young healthy adults. Moreover, elasticity was affected by sex, but not by leg dominance. Clinically, in a rehabilitation regimen, attention should be paid to exercises that could increase stiffness accompanying flexion of the knee to avoid further tendon damage as risk management in the acute phase.

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The main purposes of the current study were to examine bilateral asymmetry in postural control during single-leg standing between the dominant and non-dominant legs using a novel analysis approach based on principal component analysis (PCA). It was hypothesized that the asymmetry might manifest as differences in the coordinative structure (control strategies), or as differences in the frequency or regularity of corrective interventions of the motor control system. The static and dynamic leg dominance of 26 active young adults (14 males and 12 females) was determined from their preferred leg for dynamic and for static tasks. Then postural movements during one-leg standing were recorded with a standard marker-based motion capture system and analyzed by a PCA. The coordinative structure of postural movements was quantified using the relative variance of the principal movement components (PMs). Then the PMs were differentiated to obtain postural accelerations, from which two variables characterizing the activity (frequency and regularity) of the postural control system were derived. There were no differences in the coordinative structure, neither for dynamic nor for static leg preference. However, both variables characterizing asymmetries in the postural accelerations showed significant differences in specific PMs. Dynamic leg dominance yielded more and larger effects than static leg dominance. In the opinion of the authors, the PM-specificity of limb dominance agrees with principles of movement control derived from optimal feedback control theory. In summary, the current study suggests that leg dominance should be considered in clinical testing; different effects in different movement components should be expected; and one-leg standing should be seen as a dynamic, rather than as a static task.

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