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Clinical Scenario: Hamstring extensibility plays a significant role in maintaining postural alignment essential for a functional musculoskeletal system. When hamstring extensibility is lacking, individuals are placed at a higher risk for developing various lumbar spine, pelvis, knee, and foot dysfunctions. Limited hamstring extensibility is common, occurring in as much as 40% of college students and 86% of the adult population. Therefore, it is essential to maintain hamstring extensibility, which can be aided by understanding intervention effectiveness for improving flexibility. Purpose: To critically appraise the literature on the effectiveness of Active Release Technique (ART) for the treatment of hamstring extensibility deficits. Clinical Question: What is the effect of ART in a healthy population with or without hamstring extensibility deficits? Summary of Key Findings: Three studies were included for critical appraisal. Two studies concluded a single treatment session of ART that individuals possessing limited straight leg raise range of motion experienced improved active knee extension, popliteal angle, and sit-and-reach test measures. In the third study, a single session of ART was effective at improving hamstring extensibility in males without hamstring extensibility dysfunction. Clinical Bottom Line: Based on the current level 1 and level 3 evidence, ART may be an effective treatment to produce acute increases in hamstring extensibility. Future research is still needed. Strength of Recommendation: Level B evidence exists to support the use of ART to improve hamstring extensibility in the healthy population. [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD) is a neurodegenerative disorder and always results in balance loss. Although studies in lower-extremity exoskeleton robots are ample, applications with a lower-extremity exoskeleton robot for PD patients are still challenging. This paper aims to develop an effective assistive control for PD patients with a lower-extremity exoskeleton robot to maintain standing balance while being subjected to external disturbances. When an external force is applied to participants to force them to lose balance, the hip strategy for balance recovery based on the zero moment point (ZMP) metrics is used to generate a reference trajectory of the hip joint, and then, a model-free linear extended state observer (LESO)-based fuzzy sliding mode control (FSMC) is synthesized to regulate the human body to recover balance. Balance recovery trials for healthy individuals and PD patients with and without exoskeleton assistance were conducted to evaluate the performance of the proposed exoskeleton robot and balance recovery strategy. Our experiments demonstrated the potential effectiveness of the proposed exoskeleton robot and controller for standing balance recovery control in PD patients. [ABSTRACT FROM AUTHOR]

Context: Current lower-extremity return to sport testing primarily considers the physical status of an athlete; however, sport participation requires continuous cognitive dual-task engagement. Therefore, the purpose was to develop and evaluate the reliability of a visual-cognitive reactive (VCR) triple hop test that simulates the typical sport demand of combined online visual-cognitive processing and neuromuscular control to improve return to sport testing after lower-extremity injury. Design: Test–retest reliability. Methods: Twenty-one healthy college students (11 females, 23.5 [3.7] y, 1.73 [0.12] m, 73.0 [16.8] kg, Tegner Activity Scale 5.5 [1.1] points) participated. Participants performed a single-leg triple hop with and without a VCR dual task. The VCR task incorporated the FitLight system to challenge peripheral response inhibition and central working memory. Maximum hop distance, reaction time, cognitive errors, and physical errors were measured. Two identical testing visits were separated by 12 to 17 days (14 [1] d). Results: Traditional triple hop (intraclass correlation coefficients: ICC(3,1) =.96 [.91–.99]; standard error of the measurement = 16.99 cm) and the VCR triple hop (intraclass correlation coefficients(3,1) =.92 [.82–.97]; standard error of the measurement = 24.10 cm) both demonstrated excellent reliability for the maximum hop distance, and moderate reliability for the VCR triple hop reaction time (intraclass correlation coefficients(3,1) =.62 [.09–.84]; standard error of the measurement = 0.09 s). On average, the VCR triple hop resulted in a hop distance deficit of 8.17% (36.4 [5.1] cm; P <.05, d = 0.55) relative to the traditional triple hop. Conclusions: Hop distance on the VCR triple hop had excellent test–retest reliability and induced a significant physical performance deficit when compared with the traditional triple hop assessment. The VCR triple hop reaction time also demonstrated moderate reliability. [ABSTRACT FROM AUTHOR]

Context: Induced mental fatigue negatively impacts sport performance and neurocognition. However, it is unclear how induced mental fatigue influences landing biomechanics. The purpose of this study was to examine the influence of mental fatigue on drop landing biomechanics in individuals with and without a concussion history. Design: Crossover design. Methods: Forty-eight (24 per group) recreationally active individuals were matched on age (±3 y), sex, and body mass index (±1 kg/m²). All participants completed an experimental (30-min Stroop task) and control (30-min reading magazines) intervention on separate days separated by a minimum of 24 hours. Drop landings were performed before and after both interventions. Outcomes included peak vertical ground reaction force (vGRF), vertical loading rate (VLR), knee flexion angle, knee abduction angle, external knee flexion moment, external knee abduction moment, and initial ground contact knee flexion and knee abduction angles. Separate 2 (group) x 2 (intervention) between-within analyses of covariance compared drop landing outcomes. Each group's average pre-Stroop and premagazine outcomes were covariates. Results: There was a significant interaction for vGRF (P = .033, ηp²=.097) and VLR (P = .0497, ηp²=.083). The vGRF simple effects were not statistically significantly (P range = .052-.325). However, individuals with a concussion history displayed a medium effect size for greater vGRF post-Stroop compared with their own postmagazine vGRF (mean difference (95% confidence interval [95% CI] = 0.163 (-0.002 to 0.327) bodyweight (BW), p =.052, ηp²=.081. In contrast, the control group displayed a small effect size (mean difference [95% CI] = 0.095 [-0.069 to 0.259] BW, p =.251, ηp²=.029). Individuals with a concussion history displayed greater VLR post-Stroop compared with controls (mean difference [95% CI], 26.29 [6.19 to 46.40] BW/s, P = .012, ηp²=.134) and their own postmagazine values (mean difference [95% CI] = 32.61 [7.80 to 57.42] BW/s, p =.011, ηp²=.135). Conclusion: Mental fatigue leads to greater VLR for individuals with a concussion history. Athletic competition and activities of daily living can increase mental fatigue. Training programs may seek to teach mental fatigue reducing strategies to athletes with a concussion history. [ABSTRACT FROM AUTHOR]

Context: In human movement analysis, normalization of a surface electromyography signal is a crucial step; therefore, parameter selection for this procedure must be adequately justified. The aim of this research was to determine the variability of electromyography signals in eccentric hamstring contraction under different normalization parameters. Design: Cross-sectional study. Methods: Nine university rugby players (age 21.50 [3.61] y; body mass index 21.50 [4.95]) and no history of recent hamstring injury. Values from maximum voluntary isometric contraction protocol and task related (ie, Nordic hamstring exercise) were used for surface electromyography signal normalization. Intersubject and intrasubject variation coefficients were used for normalization method variability and for signal reproducibility, respectively. Results: Intrasubject variation coefficient value indicates acceptable reproducibility of surface electromyography (less than 12%) for all normalization procedures. Lower values of intersubject variation coefficient value were achieved for normalization procedures using task-related values. Conclusion: Parameters extracted from task execution provided less variability for surface electromyography amplitude normalization in eccentric hamstring muscle contractions. [ABSTRACT FROM AUTHOR]

Context: Poor lower-extremity biomechanics are predictive of increased risk of injury. Clinicians analyze the single-leg squat (SLS) and step-down (SD) with rubrics and 2D assessments to identify these poor lower-extremity biomechanics. However, evidence on measurement properties of movement assessment tools is not strongly outlined. Measurement properties must be established before movement assessment tools are recommended for clinical use. Objective: The purpose of this study was to systematically review the evidence on measurement properties of rubrics and 2D assessments used to analyze an SLS and SD. Evidence Acquisition: The search strategy was developed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines. The search was performed in PubMed, SPORTDiscus, and Web of Science databases. The COnsensus-based Standards for the selection of health Measurement DMstruments multiphase procedure was used to extract relevant data, evaluate methodological quality of each study, score the results of each movement assessment, and synthesize the evidence. Evidence Synthesis: A total of 44 studies were included after applying eligibility criteria. Reliability and construct validity of knee frontal plane projection angle was acceptable, but criterion validity was unacceptable. Reliability of the Chmielewski rubric was unacceptable. Content validity of the knee-medial-foot and pelvic drop rubrics was acceptable. The remaining rubrics and 2D measurements had inconclusive or conflicting results regarding reliability and validity. Conclusions: Knee frontal plane projection angle is reliable for analyzing the SLS and SD; however, it does not serve as a substitute for 3D motion analysis. The Chmielewski rubric is not recommended for assessing the SLS or SD as it may be unreliable. Most movement assessment tools yield indeterminate results. Within the literature, standardized names, procedures, and reporting of movement assessment tool reliability and validity are inconsistent. [ABSTRACT FROM AUTHOR]

Clinical Scenario: Knee pathologies often require rehabilitation to address the loss of knee-extensor (KE) strength, function, and heightened pain. However, in the early stages of rehabilitation, higher loads may be contraindicated. Blood flow restriction (BFR) resistance training does not require high loads and has been used clinically to promote strength improvements in a variety of injured populations. BFR resistance training may be an effective alternative to high-intensity resistance training during early rehabilitation of knee pathologies. Clinical Question: Following a knee injury, does BFR resistance training improve KE strength and function, and reduce patient-reported pain? Summary of Key Findings: Four randomized controlled trial studies met the inclusion criteria. Each included study evaluated the use of BFR resistance training on knee pathologies and the effects on KE strength, functional outcomes, and pain compared with high- or low-load resistance training. All 4 studies reported significant improvements in KE strength, function, and pain through a variety of outcome measures, following BFR resistance training use as the treatment. Clinical Bottom Line: There is consistent evidence to support the use of BFR resistance training as a treatment intervention following knee injury and as a means to improve KE strength and function and to reduce pain. Strength of Recommendation: Grade A evidence supporting the use of BFR resistance training for improvement in KE strength and function, and the reduction of patient-reported pain following an acute or chronic knee pathology. [ABSTRACT FROM AUTHOR]

Context: Strength deficits and decreased scores on generic, dimension-specific, and region-specific health-related quality of life (HRQL) PRO measures are commonly documented among individuals with chronic ankle instability (CAI). However, it is unknown if there is a relationship between hip strength and self-reported patient-reported outcome (PRO) scores. Objective: To compare isometric peak torque for hip-extension (H-EXT) and hip-abduction (H-ABD), as well as PRO scores between CAI, lateral ankle sprain copers (LAS copers), and uninjured controls (UC). The secondary purpose was to examine the relationship between isometric hip peak torque and PROs in participants with CAI. Design: Cross-sectional. Setting: Laboratory. Participants: Sixty-three individuals, 45 women (23.02 [3.83] y, 165.91 [7.55] cm, 67.28 [11.95] kg) and 18 men (26.28 [5.43] y, 179.28 [9.01] cm, 83.87 [13.26] kg), grouped as uninjured control (n = 26), LAS coper (n = 15), or CAI (n = 22). Main Outcome Measures: The Foot and Ankle Ability Measure was used to assess region-specific HRQL. The Fear Avoidance Beliefs Questionnaire was used to assess injury-related fear. The Disablement in Physically Active was used to assess global HRQL. Isometric peak torque was measured with a handheld dynamometer for H-EXT and H-ABD. Results: No group differences were observed for H-ABD (P = .34) or H-EXT (P = .35). The CAI group had significantly worse scores on all PROs compared with LAS coper (P < .001) and HC (P < .001). Moderate-weak correlations were found between H-ABD and Foot and Ankle Ability Measure--activities of daily living (P = .047; ρ = .392) and Foot and Ankle Ability Measure-Sport (P = .013; ρ = .482) and H- EXT and Fear Avoidance Beliefs Questionnaire-Work (P = .007; ρ = -.517). Conclusions: Individuals with CAI displayed lower HRQL based on worse scores on generic, dimension-specific, and region-specific PROs compared with LAS copers and uninjured controls. There were no significant between-group differences for H-EXT and H-ABD isometric peak torque production, but there was a moderate positive relationship between isometric H-ABD and self-reported ankle disability in individuals with CAI. [ABSTRACT FROM AUTHOR]

Context: Examining the coordinated coupling of muscle recruitment patterns may provide insight into movement variability in sport-related tasks. Objective: The purpose of this study was to examine the relationship between coupled gluteus maximus and medius recruitment patterns and hip-adduction variability during single-limb step-downs. Design: Cross-sectional. Setting: Biomechanics laboratory. Participants: Forty healthy adults, including 26 women and 14 men, mean age 23.8 (1.6) years, mean body mass index 24.2 (3.1) kg/m2, participated. Interventions: Lower-extremity kinematics were acquired during 20 single-limb step-downs from a 19-cm step height. Electromyography (EMG) signals were captured with surface electrodes. Isometric hip-extension strength was obtained. Main Outcome Measures: Hip-adduction variability, measured as the SD of peak hip adduction across 20 repetitions of the step-down task, was measured. The mean amplitudes of gluteus maximus and gluteus medius EMG recruitment were examined. Determinism and entropy of the coupled EMG signals were computed with cross-recurrence quantification analyses. Results: Hip-adduction variability correlated inversely with determinism (r = −.453, P =.018) and positively with entropy (r =.409, P =.034) in coupled gluteus maximus/medius recruitment patterns but not with hip-extensor strength nor with magnitudes of mean gluteus maximus or medius recruitment (r = −.003,.081, and.035; P =.990,.688, and.864, respectively). Conclusion: Hip-adduction variability during single-limb step-downs correlated more strongly with measures of coupled gluteus maximus and medius recruitment patterns than with hip-extensor strength or magnitudes of muscle recruitment. Examining coupled recruitment patterns may provide an alternative understanding of the extent to which hip neuromuscular control modulates lower-extremity kinematics beyond examining muscle strength or EMG recruitment magnitudes. [ABSTRACT FROM AUTHOR]

Context: Joint loading following anterior cruciate ligament reconstruction (ACL-R) is thought to influence long-term outcomes. However, our understanding of the role of meniscus repair at the time of ACL-R on early joint loading is limited. Objective: To assess if differences in total energy absorption and energy absorption contribution of the hip, knee, and ankle exist in the early stages of rehabilitation between patients who received an isolated ACL-R and those with concomitant meniscal repairs. Design: Cross-sectional. Setting: Clinical laboratory. Patients: Fifty-nine human subjects, including 27 who underwent ACL-R and 32 who underwent ACL-R with concomitant meniscal repairs. Main outcome measure: The total energy absorption and the energy absorption contribution of each joint of both the involved and uninvolved limbs during a double-limb squat task. Results: There were significant differences in energy absorption contribution between groups at the knee joint (P = .01) and the hip joint (P = .04), but not at the ankle joint (P = .48) of the involved limb. Post hoc analysis indicates that preoperative hip and knee loading differences exist and when you control for preoperative loading (analysis of covariance), the postsurgery difference was not significant. Conclusions: The results of the study suggest that the additional surgical procedure of MR may not have had negative effects on joint loading during squatting at 12 weeks. [ABSTRACT FROM AUTHOR]

Background: Previous work suggests that proprioceptive information from ankle and hip are crucial in maintaining balance during upright standing; however, the contribution of these proprioceptive information during stepping balance recovery in not clear. The goal of the current study was to assess the role of ankle and hip proprioceptive information on balance recovery performance by manipulating type 1a afferent in muscle spindles using vibratory stimulation. Methods: Twenty healthy young participants were recruited (age = 22.2 ± 2.7 years) and were randomly assigned to balance recovery sessions with either ankle or hip stimulation. Trip-like perturbations were imposed using a modified treadmill setup with a protecting harness. Vibratory stimulation was imposed bilaterally on ankle and hip muscles to expose participants to three condition of no-vibration, 40Hz vibration, and 80Hz vibration. Kinematics of the trunk and lower-extremities were measured using wearable sensors to characterize balance recovery performance. Outcomes were response time, recovery step length, trunk angle during toe-off and heel-strike of recovery stepping, and required time for full recovery. Findings: Ankle vibratory stimulation elicited main effects on reaction time and recovery step length (p

ABSTRACT: Background: Ultra-high field strength magnetic resonance has been proven to offer improved visualization of the distal intracranial vessels and branches, but its effectiveness for visualization of the peripheral vasculature has not been investigated. We aimed to assess the visualization of distal lower-extremity vessels using three-dimensional phase-contrast magnetic resonance angiography (3D PC-MRA) at 5T field strength in combination with warm water immersion (WWI). Methods: Participants were prospectively recruited and underwent 3T, and 5T 3D PC-MRA of the feet with and without WWI (water temperature between 40°C and 45°C for a duration of 10 minutes). Patients with suspected lower-extremity peripheral arterial disease underwent computed tomography angiography for lesion identification. Signal-to-noise ratio (SNR), subjective scoring, quantitative vessel segmentation, and flow velocity were performed to assess vessel visualization before and after WWI. Friedman’s test was conducted to determine statistical significance. Results: Out of 30 participants (mean age, 46.2 ± 5.9; males, 20; lower-extremity vessel disease, 10), 900 vessel segments were available for evaluation. 5T images showed significantly higher scores for image quality and foot vessel visualization than 3T (all P

Stroke is the leading cause of disability globally in need of novel and effective methods of rehabilitation. Intermittent theta burst stimulation (iTBS) has been adopted as a Level B recommendation for lower limb spasticity in guidelines on the therapeutic use of repetitive transcranial magnetic stimulation (rTMS). Nonetheless, the methodological differences and deficits of existing work bring about heterogenous results and therefore limit the universal clinical use of rTMS in lower extremity (LE) rehabilitation. The variation of stimulated targets across motor cortex contributes mainly to these heterogeneities. This narrative review includes studies of rTMS on LE motor function rehabilitation in patients after stroke until now. Some analyses of brain imaging and electromagnetic simulation and quantification through computational modeling were also performed. rTMS appears capable of fostering LE motor rehabilitation after stroke, but the actually stimulated targets are considerably bias making it difficult to confirm effectiveness. The main reason for this phenomenon is probably inaccurate targeting of motor cortical leg representation. An underlying updated method is proposed as Individual‐Target TMS (IT‐TMS) combined with brain imaging. rTMS is a promising validated method for LE function regaining. Future studies should systematically compare the effects of IT‐TMS with traditional rTMS using large samples in random clinical trials. This article is categorized under:Neuroscience > Clinical Neuroscience [ABSTRACT FROM AUTHOR]

Introduction: Most spinal cord injuries (SCI) result in lower extremities paralysis, thus diminishing ambulation. Using brain-computer interfaces (BCI), patients may regain leg control using neural signals that actuate assistive devices. Here, we present a case of a subject with cervical SCI with an implanted electrocorticography (ECoG) device and determined whether the system is capable of motor-imagery-initiated walking in an assistive ambulator. Methods: A 24-year-old male subject with cervical SCI (C5 ASIA A) was implanted before the study with an ECoG sensing device over the sensorimotor hand region of the brain. The subject used motor-imagery (MI) to train decoders to classify sensorimotor rhythms. Fifteen sessions of closed-loop trials followed in which the subject ambulated for one hour on a robotic-assisted weight-supported treadmill one to three times per week. We evaluated the stability of the best-performing decoder over time to initiate walking on the treadmill by decoding upper-limb (UL) MI. Results: An online bagged trees classifier performed best with an accuracy of 84.15% averaged across 9 weeks. Decoder accuracy remained stable following throughout closed-loop data collection. Discussion: These results demonstrate that decoding UL MI is a feasible control signal for use in lower-limb motor control. Invasive BCI systems designed for upper-extremity motor control can be extended for controlling systems beyond upper extremity control alone. Importantly, the decoders used were able to use the invasive signal over several weeks to accurately classify MI from the invasive signal. More work is needed to determine the long-term consequence between UL MI and the resulting lower-limb control. [ABSTRACT FROM AUTHOR]

Lower-limb prostheses aim to restore ambulatory function for individuals with lower-limb amputations. While the design of lower-limb prostheses is important, this paper focuses on the complementary challenge—the control of lower-limb prostheses. Specifically, we focus on powered prostheses, a subset of lower-limb prostheses, which utilize actuators to inject mechanical power into the walking gait of a human user. In this paper, we present a review of existing control strategies for lower-limb powered prostheses, including the control objectives, sensing capabilities, and control methodologies. We separate the various control methods into three main tiers of prosthesis control: High-level control for task and gait phase estimation, mid-level control for desired torque computation (both with and without the use of reference trajectories), and low-level control for enforcing the computed torque commands on the prosthesis. In particular, we focus on the high- and mid-level control approaches in this review. Additionally, we outline existing methods for customizing the prosthetic behavior for individual human users. Finally, we conclude with a discussion on future research directions for powered lower-limb prostheses based on the potential of current control methods and open problems in the field. [ABSTRACT FROM AUTHOR]

Context: Kinesio tape (KT) is a widely used intervention in the fields of sports and rehabilitation. However, its effects on lower-extremity behavior during functional activities are not entirely known. Objective: To test the hypothesis that application of KT can change performance and vertical stiffness (VS) during the countermovement jump (CMJ) before and after a fatigue protocol. Design: A predesign and postdesign to study the effect of KT in 2 situations, prefatigue and postfatigue. In each fatiguing condition, there were 2 conditions with and without KT application on the gastrocnemius muscle. Setting: Biomechanics laboratory. Participants: Fifty healthy, nonathlete participants (26 females and 24 males). Interventions: KT application on the gastrocnemius muscle and a fatigue protocol to induce fatigue in plantar flexor muscles. Main Outcome Measures: Various jumping parameters, including jump height, maximum force, maximum power, rate of force development, eccentric lower-limb stiffness, and VS, were calculated using the vertical ground reaction force data. Eccentric lower-limb stiffness and VS were calculated using a mass-spring model. The studied variables can present lower-extremity elastic behavior and performance during CMJ. Results: The results of a 2-way repeated-measures analysis of variance showed no significant effect for KT application. Fatigue resulted in lower values of jump height, maximum power, and VS. Moreover, male subjects showed greater values of jump height, maximum force, and maximum power than did females. Conclusions: The main finding of this study was that gastrocnemius KT has no effect on performance or elastic behavior of the lower-extremity during CMJ. Moreover, KT cannot reduce the adverse effect of fatigue in a functional activity such as CMJ. It seems that gastrocnemius KT is not effective for demanding activities. [ABSTRACT FROM AUTHOR]

Introduction: Most spinal cord injuries (SCI) result in lower extremities paralysis, thus diminishing ambulation. Using brain-computer interfaces (BCI), patients may regain leg control using neural signals that actuate assistive devices. Here, we present a case of a subject with cervical SCI with an implanted electrocorticography (ECoG) device and determined whether the system is capable of motor-imagery-initiated walking in an assistive ambulator.Methods: A 24-year-old male subject with cervical SCI (C5 ASIA A) was implanted before the study with an ECoG sensing device over the sensorimotor hand region of the brain. The subject used motor-imagery (MI) to train decoders to classify sensorimotor rhythms. Fifteen sessions of closed-loop trials followed in which the subject ambulated for one hour on a robotic-assisted weight-supported treadmill one to three times per week. We evaluated the stability of the best-performing decoder over time to initiate walking on the treadmill by decoding upper-limb (UL) MI.Results: An online bagged trees classifier performed best with an accuracy of 84.15% averaged across 9 weeks. Decoder accuracy remained stable following throughout closed-loop data collection.Discussion: These results demonstrate that decoding UL MI is a feasible control signal for use in lower-limb motor control. Invasive BCI systems designed for upper-extremity motor control can be extended for controlling systems beyond upper extremity control alone. Importantly, the decoders used were able to use the invasive signal over several weeks to accurately classify MI from the invasive signal. More work is needed to determine the long-term consequence between UL MI and the resulting lower-limb control.

Backgrounds: Previous reports revealed that balance and stability are essential for human physical activity. The present study aimed to evaluate the comparative outcome of a novel beginning movement load training (BMLT) versus conventional leg press training in terms of improvement of lower-extremity stability.Research Question: Does the leg press training improve the stability of lower extremities?Methods: Twenty adult, asymptomatic and active amateur basketball players were enrolled in this study and randomized in equal numbers into a BMLT group (study group) and a conventional leg press training group (control group).Results: The results after eight-week course of training showed that conventional leg press training had an opposite effect on dynamic stability in the left leg (p = 0.015) and backward movement of the right leg (p = 0.038). The athletes in the study group revealed superior dynamic stability maintenance in both legs backwards (p = 0.001), the left leg (p = 0.013), the right leg backwards (p = 0.022) and overall stability (p = 0.002).Significance: The study group showed better postural stability in terms of the medial/lateral index (p = 0.017), and the athletes in the control group exhibited a significant inability to maintain postural stability in the medial/lateral aspect after the training (p = 0.016). Rotational BMLT lower-extremity press training yielded superior enhancement of dynamic stability and maintenance of center of gravity and postural stability. [ABSTRACT FROM AUTHOR]

There is growing concern over the safety of artificial turf when it comes to the incidence of player injuries. The artificial surfaces can withstand more play, are cheaper to maintain, and are more predictable. However, there is concern that this beneficial durability comes at the expense of the forgiveness of the surface, leading to more injuries. In this study, we aim to compare the incidence of in-game season-ending lower extremity injuries on natural and artificial playing surfaces in the National Football League (NFL) during the 2020, 2021, and 2022 seasons. For this study, we used publicly available data to determine and classify the specific injury, where the injury occurred, field surface type, and duration of recovery. All data were collected, and significance was determined using two-sample T -tests. Only in-game injuries were included in this study. Over the course of 2020, 2021, and 2022, there were 199 season-ending lower-extremity injuries. Of these, 79 occurred on natural turf (39.7%) and 120 on artificial turf (60.3%). Of the 891 games played in this three-year period, 396 were played on natural turf (44.4%) and 495 were played on artificial turf (55.6%). Natural turf saw an injury rate of 0.199 per game, and artificial turf saw 0.242 injuries per game. We determined that there is no significant difference in rates of season-ending lower-extremity injury between artificial and natural turf. Any perceived difference in injury rates could possibly be attributed to the increased amount of play on artificial surfaces and anecdotal evidence related to high profile cases. While there is no significant difference in incidence, surfaces should continue to be monitored and regulated for traits such as hardness, and player preferences should be considered for qualities that are not quantifiable., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2024 William F. McCormick et al.)

Objective: Lower-extremity transcutaneous osseointegration is a rehabilitation alternative to socket-suspended prostheses. The rehabilitation process, philosophies, and routines remain under-described. This review, primarily, identifies commonalities and differences among protocols. Secondarily, strategies are proposed to streamline future research of post-osseointegration surgery rehabilitation., Methods: Two differently phrased queries of Google Scholar, Pubmed, Embase, and Web of Science were performed. First using either "osseointegration" or "osseointegrated" or "bone anchored prosthesis" AND [last name]. Second, replacing author name with "physical therapy" or "rehabilitation." Six hundred eighty-eight articles were identified describing lower-extremity rehabilitation following osseointegration. Following software-based deduplication, manual abstract and full-text review, article reference evaluation, and use of Google Scholar's "Cited by" feature, 35 studies were fully analyzed. First, a consolidated summary was made of protocols focusing on stages, timing, and other descriptions of postoperative rehabilitation. Subsequently, strengths and limitations of protocols were considered to propose potential strategies to investigate and optimize postoperative rehabilitation., Results: All articles describe rehabilitation having this same order of goal progression: from surgery to gradual weight bearing and final goal of independent ambulation. The most impactful difference influencing the stated final goal of independent ambulation was whether 1 or 2 surgical stages were performed. No articles reported patient success rate achieving proposed goals and timing, or challenges during rehabilitation. Therefore, the first research suggestion is to investigate actual success rates achieving proposed goals and timing. Second, to further explore rehabilitation of performance deficits, beyond unaided ambulation. Finally, to incorporate technology such as mobility trackers to more objectively understand prosthesis use and mobility., Conclusion: All lower-extremity osseointegration rehabilitation literature recommends identical goal progression order. No studies evaluate patient challenges or variation. Understanding and addressing such challenges may enhance postoperative rehabilitation., Impact: This article consolidates published rehabilitation protocols post-osseointegration surgery. Specific analysis and experimentation of the protocols may enhance the uniformity and potential of patient rehabilitation., (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Physical Therapy Association.)

BackgroundAcquired alopecia of the lower legs may occur secondary to friction due to socks, footwear, or both on the lower extremities. There is scant literature that reports on this phenomenon.Methods and MaterialsWe describe 5 patients who presented with alopecia of their lower legs induced by socks, footwear, or both.Methods and Materials: We reviewed PubMed for the following terms: ankle alopecia, friction alopecia, frictional alopecia, lower extremity alopecia, non-scarring leg alopecia, and sock alopecia. We also reviewed papers containing these terms and their references.ResultsAcquired frictional alopecia of the lower extremities is often an asymptomatic condition found incidentally on physical examination. The condition can persist for many years despite removal of the source of friction.ConclusionThe incidence of acquired frictional alopecia of the lower extremities may be greater than reflected in previously published reports. It is a non-scarring subtype of alopecia that was noted as an incidental finding during the patient’s dermatology appointment.

Objective: To better evaluate the relationships between training, demographics, and injury, this study sought to define race-related injury risk factors for half- and full-marathon runners. Design: This 3-year, observational cross-sectional study included adults who participated in a half or full marathon. Prerace and 2-week postrace surveys collected data on demographics, training factors, and injuries. Setting: This study took place during a nationally recognized marathon affiliated with a local hospital. Participants: Runners were recruited during the Expo in the days before the race. Postrace surveys were returned by 1043 half marathoners and 624 full marathoners (response rate, 83%). Interventions: This was an observational study; independent variables included demographic data and race year. Main Outcome Measure: The primary outcome was race-related injury that occurred during the race or within 2 weeks after the race. Results: Race-related injuries were reported by 24% of half marathoners and 30% of full marathoners. For half and full marathoners, respectively, significant factors for injuries were previous injury, lower peak weekly training mileage, and lower weekly mileage before race training. Factors significant for only half-marathon injuries were younger age, female sex, shorter distance of longest training run, and no formal training program. Factors significant for only full-marathon injuries were higher body mass index, fewer days running per week, and fewer years of running experience. Conclusions: Previous running injuries, undertraining, and inexperience increased race-related injury risk; women had higher risk than men. Decreased risk of injury was associated with training loads of greater than 23 miles/week for half marathoners and 40 miles/week for full marathoners. [ABSTRACT FROM AUTHOR]

Lowerextremity musculoskeletal injuries in soccer are common among sexes. However, it remains unknown whether differences between sexes exist with regard to absolute or relative hip strength and how these differences may relate to injury. In the current study, we performed a retrospective cross-sectional analysis of pre-season data from male (♂n = 21) and female (♀n = 19) professional United States soccer organizations. Two years of pre-season data were collected for peak strength of lower extremity and hip musculature (no duplicates used). A 2 x 2 multivariate analysis of variance was used to detect differences in hip strength between sexes and dominant compared with nondominant legs. For all significant multivariate effects indicated by Wilks lambda and follow-up univariate analysis, a Tukey’s post hoc test was used for pairwise univariate comparisons. A 2-tailed independent-samples T-test was used for comparison of height, body mass, body mass index (BMI), mean leg length, and strength ratios between dominant and nondominant limbs between sexes. Type I error was set at a = 0.05 for all analyses. Height (♂183.1 6 6.8 cm, ♀170.0 6 5.5 cm), body mass (♂79.0 6 8.7 kg, ♀65.1 6 5.6 kg), BMI (♂23.5 6 1.3 kg·m-2, ♀22.5 6 1.4 kg·m-2), and mean leg length (♂95.5 6 4.34 cm, ♀ 88.3 6 3.24 cm) differed between groups (p, 0.05). Sex differences (p, 0.05) were also found for hip abduction (dominant ♂19.5 6 3.6 kg, ♀17.3 6 2.2 kg; nondominant ♂18.5 6 3.7 kg, ♀16.0 6 2.3 kg), adduction (dominant ♂19.8 6 3.0 kg, ♀16.7 6 2.3 kg; nondominant ♂20.1 6 2.9 kg, ♀17.6 6 2.9 kg), external rotation (dominant ♂21.7 6 3.4 kg, ♀17.7 6 2.4 kg; nondominant ♂21.6 6 3.9 kg, ♀16.8 6 2.1 kg), and dominant hamstring strength (♂27.9 6 6.5 kg, ♀23.0 6 4.9 kg). The ratio of hip internal to external rotation strength differed in the nondominant leg (♂1.1 6 0.2, ♀0.9 6 0.2, p, 0.05). No significant differences were found between males and females when measures were normalized to body mass. These findings provide baseline pre-season normative data for professional soccer athletes and indicate that strength differences can be expected among different sexes, but are attenuated with attention to body mass. Further research should indicate how pre-season strength measures relate to injury. [ABSTRACT FROM AUTHOR]

Background: Ballet dancers have a high prevalence of injuries to the lower extremity. Many studies have investigated the relationship between dance injury and risk factors. However, risk factors for lower-extremity injury comparing recreational- and elite-level ballet dancers are scarce. Objective: To systematically review available original studies to assess risk factors for lower-extremity injury in female ballet dancers between recreational and elite ballet dancers. Data sources: Five online databases [Web of Science, PubMed, OVID (Medline), EBSCO, and ProQuest] were searched systematically. Study selection: Included studies had an analytic study design published in the past 11 years and investigated an association between potential risk factors and lower-extremity injury in female ballet dancers. Study appraisal: Assessed independently by 2 reviewers using the Downs and Black (DB) criteria and Oxford Centre of Evidence-Based Medicine. Results: Seventeen studies were included. Alignment was a risk factor for lower-extremity injury in both recreational and elite ballet dancers. In elite ballet dancers, poor lumbopelvic movement control, inappropriate transversus abdominis contraction, decreased lower-extremity strength, and poor aerobic fitness were risk factors for lower-extremity injury. In recreational ballet dancers, hypermobility of the hip and ankle and longer training hours were risk factors for lower-extremity injury. Mean DB score was 15.94 (SD 1.57). The majority of studies were retrospective cohort studies or had poor follow-up, with 7 level 2b studies, 6 level 3b studies (cross-sectional), and 4 level 1b studies (prospective cohort with good follow-up). Conclusions: Alignment was identified as a common risk factor for recreational and elite ballet dancers. Other risk factors differed between recreational ballet dancers and elite ballet dancers. Future studies are warranted to use a prospective study design, identify dance level-specific risk factors, and implement evidence-based prevention strategies. [ABSTRACT FROM AUTHOR]

Reconstruction of the heel region poses great challenge to plastic surgeons not only due to calcaneal bone lying just deep to the subdermal fat pad but also due to easily exposed Achilles tendon. In order to achieve permanent closure of the heel defect, exposed bone or tendon—or both—should be covered with durable, preferably sensate, well-vascularized, thin skin flaps. Even though fasciocutaneous free flaps remain the gold standard in the reconstruction of heel defects with exposed bone or tendon, a significant number of these patients are older individuals with multiple comorbidities such as diabetes mellitus, hypertension, atherosclerosis, and peripheral vascular disease. In this study, with a clinic series consisting of 6 patients (1 female, 5 males), we present a new technique of reconstruction with a bipedicled flap as a safe, reliable, and efficient reconstructive modality in the treatment of heel defects in cases where free flaps and other more sophisticated reconstructive options are either not feasible or have failed. Achieving complete reconstruction of defects in all 6 patients, this technique proves to be successful as a salvage procedure in reconstruction of heel defects. [ABSTRACT FROM AUTHOR]

A lower-extremity exoskeleton can facilitate the lower limbs' rehabilitation by providing additional structural support and strength. This article discusses the design and implementation of a functional prototype of lower extremity brace actuation and its wireless communication control system. The design provides supportive torque and increases the range of motion after complications reducing muscular strength. The control system prototype facilitates elevating a leg, gradually followed by standing and slow walking. The main control modalities are based on an Artificial Neural Network (ANN). The prototype's functionality was tested by time-angle graphs. The final prototype demonstrates the potential application of the ANN in the control system of exoskeletons for joint impairment therapy. [ABSTRACT FROM AUTHOR]

Limb salvage surgery has become a first-line treatment in the setting of lower extremity cancer. Despite a multitude of techniques, the most effective modality for osseous reconstruction has not been described. We aim to examine outcomes of allograft reconstruction alone compared to an allograft combined with a vascularized fibula graft (VFG) (Capanna Technique) through a meta-analysis of the literature. A systematic review of the literature was conducted through the online databases PubMed, Embase, and Web of Science, examining articles utilizing an allograft with or without an intramedullary VFG for the reconstruction of lower extremity osseous defects following oncological resection. A meta-analysis examined outcomes, including nonunion, infection, fractures, explantation, and functional limb status, that were evaluated dependent upon reconstructive modality. Twenty-five articles were deemed appropriate for inclusion. The allograft with VFG group had considerably lower rates of nonunion (13%) in comparison to the allograft alone group (21.4%) (p <.001). Rates of infection (7.9% vs. 9%, respectively) and fracture (19.6% vs. 19.1%) were not statistically different. The allograft with VFG group also had significantly lower rates of explantation (6.57%) compared to the allograft alone cohort (18.11%) (p <.001). Functional outcomes were similar across groups as measured by Musculoskeletal Tumor Society scores (88.22% vs. 87.77%). Allograft reconstruction with a supplementary inlay VFG decreases the risk of nonunion and explantation compared to allograft alone reconstruction in the setting of oncological resection of the osseous lower extremity. This technique warrants increased consideration in the operative planning of lower limb reconstruction following tumor extirpation. [ABSTRACT FROM AUTHOR]

Lower-limb functional capacity is impaired in most people with multiple sclerosis (PwMS). Reductions in lower-extremity muscle mechanical function (e.g., muscle strength) appear to have critical implications for lower-limb functional capacity. However, no review has summarized the current knowledge about the importance of muscle strength for functional tasks in PwMS. Expanding the current knowledge would advance the design of both clinical and research interventions aiming to improve functional capacity in PwMS. (1) To identify studies that measured lower-extremity muscle mechanical function and lower-limb functional capacity outcomes in PwMS, and (2) to map associations between muscle strength and functional capacity. This review was based on a literature search (databases: PubMed, Embase). Included studies had to report data on lower-extremity muscle mechanical function and lower-limb functional capacity outcomes in PwMS. The associations between muscle strength and functional capacity were analyzed by using the reported correlation coefficients (R) recalculated to the determination coefficient R2. Randomized trials and observational studies were included. A total of 59 articles were reviewed; 17 (773 participants) reported associations between muscle strength and functional capacity. Lower-extremity muscle mechanical function explained a significant part of the variance in most lower-limb functional capacity tests (approximately 20–30%). This was particularly evident in muscle strength from the weakest leg. Muscle strength was predominantly tested on knee extensors and knee flexors by using isokinetic dynamometry during maximal isometric (0°/s) and dynamic (30–60°/s) contractions. Walking tests such as the timed 25-Foot Walk Test and 10-Min, 2-Min and 6-Min Walk Test were the most frequently performed functional capacity tests. In PwMS, muscle strength of particularly the weakest limb explains 20% to 30% of the variance across a number of lower-limb functional capacity tests. Thus, exercise programs should focus on increasing lower-extremity muscle mechanical function in PwMS and minimizing strength asymmetry between limbs. [ABSTRACT FROM AUTHOR]

This study investigated changes in lower-extremity joint work and power during the swing phase in a maximal accelerated sprinting. Twelve male sprinters performed 60 m maximal sprints while motion data was recorded. Lower-extremity joint work and power during the swing phase of each stride for both legs were calculated. Positive hip and negative knee work (≈4.3 and ≈−2.9 J kg−1) and mean power (≈13.4 and ≈−8.7 W kg−1) during the entire swing phase stabilized or decreased after the 26.2±1.1 (9.69±0.25 m s−1) or 34.3±1.5 m mark (9.97±0.26 m s−1) during the acceleration phase. In contrast, the hip negative work and mean power during the early swing phase (≈7-fold and ≈3.7-fold increase in total), as well as the knee negative work and power during the terminal swing phase (≈1.85-fold and ≈2-fold increase in total), increased until maximal speed. Moreover, only the magnitudes of increases in negative work and mean power at hip and knee joints during the swing phase were positively associated with the increment of running speed from the middle of acceleration phase. These findings indicate that the roles of energy generation and absorption at the hip and knee joints shift around the middle of the acceleration phase as energy generation and absorption at the hip during the late swing phase and at the knee during early swing phase are generally maintained or decreased, and negative work and power at hip during the early swing phase and at knee during the terminal swing phase may be responsible for increasing running speed when approaching maximal speed.

Background: Vascular surgical site infections have been reported with an overall incidence of 5-10% for patients undergoing arterial interventions and as high as 10-20% for lower-limb bypass grafting procedures. Given that vascular surgery patients are known to be at a higher risk of postoperative wound infections and other complications, our objective was to evaluate a potential method to reduce such complications. This study compares the rate of wound healing complications between incisional negative pressure wound therapy (NPWT) and conventional dressings in vascular surgery patients with infra-inguinal incisions. The primary endpoint is complete closure of the wound at the 2-week follow-up appointment. Secondary endpoints include frequency infections requiring antibiotics, need for wound revision, and wound dehiscence., Methods: A prospective cohort study with retrospective control group was performed following infra-inguinal vascular surgeries for peripheral arterial disease at the Mount Carmel Health System. The patients included in this study were those who underwent a lower-extremity vascular procedure with primary closure of an incision distal to the groin between January 2014 and July 2018. Patients that had received an infra-inguinal incision with primary closure were included. Patients in the experimental group who had a Prevena Wound VAC were compared with a retrospectively obtained control arm treated with conventional dressings. Data regarding wound healing and complications, specifically infections and wound dehiscence, were obtained., Results: A total of 201 patients were recruited in our study: 64 in the Prevena group and 137 in the control group. There was a significant reduction in the number of open wounds in the Prevena group compared to the control group at the 2-week follow-up (10.9% Prevena vs 33.6% control; p = .0005). When evaluated in aggregate, there was a statistically significant reduction in the number of patients who succumbed to any complication in the Prevena arm compared with traditional dressings (13 (20.3%) Prevena vs 72 (52.6%) control; p < .0001)., Conclusion: The results of our study suggest there should be a significant consideration for the use of NPWT as a prophylactic measure to reduce the risk of wound complications of primarily closed infra-inguinal incisions in vascular surgery patients following common vascular procedures. Its use is particularly effective for patients at enhanced risk of infection, especially those with poor vascularization from BMI, smoking, and diabetes. This leads to decreased trends in antibiotic use, ED visits, readmissions, and surgical revisions, which translates to decreased utilization of hospital resources and economic burden., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Bilateral strength asymmetries have been related to lower-limb injury in athletes. Given that military populations often participate in recreational sport, in addition to a physically demanding workload, bilateral strength asymmetries may be related to injury in military populations. The purpose of this study was to determine whether isokinetic strength differs between Operators with/without self-reported knee injury (KI), and to examine the odds of displaying a lower-extremity strength asymmetry based on previous KI history. Operators (n = 150) self-reported injury history and performed isokinetic knee strength testing. Cohorts were separated by those who reported/not reported KI. Mean isokinetic knee strength and odds ratios, with subjects' KI history compared with strength differences: <10, 10-20, and >20%, were calculated. Operators who reported KI demonstrated larger bilateral knee extension (KE) strength differences compared with those who did not report an injury (injured: 13.5 ± 12.9% vs. noninjured: 8.1 ± 5.9%, p = 0.01). Operators with <10 or 10-20% KE strength difference had 76-77% reduced odds of previous KI, compared to those with >20% strength difference (p < 0.05). Operators with previous KI demonstrated bilateral differences in KE strength. Those with <10 or 10-20% strength differences had reduced odds of reporting previous KI. Strength and conditioning professionals should consider unilateral, targeted exercises in reducing bilateral asymmetry to rectify more balanced strength between limbs. Targeted exercise programs may improve bilateral strength differences and limit reinjury risk. [ABSTRACT FROM AUTHOR]

Background: Excess body mass alters gait biomechanics in a distribution-specific manner. The effects of adding mass centrally or peripherally on biomechanics during sitting and rising from a chair are unknown.Methods: Motion analysis and lower extremity EMG were measured for fifteen healthy, normal weight subjects during sit-to-stand (SitTS) and stand-to-sit (StandTS) from a chair under unloaded (UN), centrally loaded (CL), and peripherally loaded (PL) conditions.Results: Compared to UN, PL significantly increased support width (SitTS and StandTS), increased peak trunk flexion velocity (SitTS), and trended to increase peak trunk flexion angle (SitTS). During StandTS, CL significantly reduced peak trunk flexion compared to UN and PL. EMG activity of the semitendinosus, vastus lateralis and/or medialis was significantly increased in CL compared to UN during SitTS and StandTS.Conclusions: Adding mass centrally or peripherally induces contrasting biomechanical strategies to successfully sit or rise from a chair. CL limits trunk flexion and increases knee extensor muscle activity whereas; PL increases support width and trunk flexion, thus preventing increased EMG activity. [ABSTRACT FROM AUTHOR]

Clinical Scenario: Patellofemoral pain (PFP) is a widespread knee disorder encountered in clinical practice. Clinicians have often focused on strengthening hip and knee musculature to improve pain and disability, which are the ultimate clinical goals of PFP treatment. However, PFP literature has shown improvement in pain and disability without concurrent changes in lower-extremity strength after rehabilitation. Although some researchers have achieved a significant increase in strength after rehabilitation in PFP cohorts, there was no association with improved pain and disability. The inconsistent improvements in strength and the lack of association with clinical outcomes call for a critical appraisal of the available evidence to better understand the association between changes in hip and knee strength and improved clinical outcomes in individuals with PFP., Clinical Question: Are changes in hip and knee strength associated with improved pain and disability after rehabilitation in individuals with PFP?, Summary of Key Findings: Four studies met the inclusion criteria and were included in the appraisal. Following rehabilitation, one study achieved strength improvements in knee extension. One study achieved strength improvements in knee extension, but not in hip external rotation and hip abduction. Two studies did not achieve strength improvements in hip external rotation, hip abduction, hip extension, or knee extension. All included studies achieved improvements in pain or disability after rehabilitation. None of the studies found a significant association between changes in hip and knee strength (either improved or not) and improved pain and disability., Clinical Bottom Line: There is consistent evidence that changes in hip and knee strength are not associated with improved clinical outcomes after rehabilitation in adults with PFP., Strength of Recommendation: Collectively, the body of evidence included is to answer the clinical question aligns with the strength of recommendation of B based on the Strength of Recommendation Taxonomy.

Objective: Aging is associated with a progressive decline in muscle strength, muscle mass and impaired physical function, which reduces mobility and impairs quality of life in the elderly population. The 6-12 months of exercise can enhance the muscle strength, but these improvements can only be maintained for a short period. In this study, we investigated the effects of long-term Tai Chi (TC) exercise on muscle strength of lower extremities. Methods: A cross-sectional study was conducted in 205 long-term TC practitioners (age: 60-89 years) and 205 age and gentle matched controls who did not practice TC. Each of the activity group was further divided into three distinct age groups: G1, 60-69 years; G2, 70-79 years; and G3, 80-89 years. Hand-held dynamometery was used to measure the maximum isometric strength of iliopsoas, quadriceps femoris, tibialis anterior and hamstrings in both sides of the participants. Unpaired t tests were performed to compare the difference of strength between the TC and non-Tai Chi (NTC) groups. Multivariate analysis of variance (MANOVA) was used to compare the lower muscle strengths among the different age groups in the TC and NTC groups. Pearson's correlations were used to quantify the linear relationship between the months of TC practice and lower limbs muscle strength. Results: The inter-rater reliabilities of iliopsoas, quadriceps femoris, tibialis anterior and hamstrings were intraclass correlation coeffificient (ICC) (1,1) = 0.895 (0.862-0.920), ICC (2,2) = 0.905 (0.874-0.928), ICC (3,3) = 0.922 (0.898-0.941) and ICC (4,4) = 0.930 (0.908-0.947). The strength of the muscles in the TC group did not differ among different age groups ( P>0.05). The strength of iliopsoas, quadriceps femoris, tibialis anterior and hamstrings in TC group was higher than that in the NTC group ( P<0.05). A correlation between muscle strength and extension of the exercise period was positive ( P<0.05). Conclusions: Results shed light on the orientation and magnitude of long-term TC in preventing muscle strength loss with aging. TC might be a good form to slow down the trend of age-related decline in muscle strength in community-dwelling population. [ABSTRACT FROM AUTHOR]

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Context: Ball velocity for baseball pitchers is influenced by a multitude of factors along the kinetic chain. While a vast amount of data currently exist exploring lower-extremity kinematic and strength factors in baseball pitchers, no previous study has systematically reviewed the available literature., Objective: The aim of this systematic review was to perform a comprehensive assessment of the available literature investigating the association between lower-extremity kinematic and strength parameters and pitch velocity in adult pitchers., Evidence Acquisition: Cross-sectional studies that investigated the association between lower-body kinematic and strength factors and ball velocity in adult pitchers were selected. A methodological index for nonrandomized studies checklist was used to evaluate the quality of all included studies., Evidence Synthesis: Seventeen studies met the inclusion criteria comprising a total of 909 pitchers (65%, professional, 33% college, and 3% recreational). The most studied elements were hip strength and stride length. The mean methodological index for nonrandomized studies score was 11.75 of 16 (range = 10-14). Pitch velocity was found to be influenced by several lower-body kinematic and strength factors including the following: (1) hip range of motion and strength of muscles around the hip and pelvis, (2) alterations in stride length, (3) alterations in lead knee flexion/extension, and (4) several pelvic and trunk spatial relationships throughout the throwing phase., Conclusions: Based on this review, we conclude that hip strength is a well-established predictor of increased pitch velocity in adult pitchers. Further studies in adult pitchers are needed to elucidate the effect of stride length on pitch velocity given mixed results across multiple studies. This study can provide a basis for trainers and coaches to consider the importance of lower-extremity muscle strengthening as a means by which adult pitchers can improve pitching performance.

Repetitive exposures to altered gait and movement following lower-limb amputation (LLA) have been suggested to contribute to observed alterations in passive tissue properties and neuromuscular control in/surrounding the lumbar spine. These alterations, in turn, may affect the synergy between passive and active tissues during trunk movements. Eight males with unilateral LLA and eight non-amputation controls completed quasi-static trunk flexion–extension movements in seven distinct conditions of rotation in the transverse plane: 0° (sagittally-symmetric), ±15°, ±30°, and ±45° (sagittally-asymmetric). Electromyographic (EMG) activity of the bilateral lumbar erector spinae and lumbar kinematics were simultaneously recorded. Peak lumbar flexion and EMG-off angles were determined, along with the difference (“DIFF”) between these two angles and the magnitude of peak normalized EMG activities. Persons with unilateral LLA exhibited altered and asymmetric synergies between active and passive trunk tissues during both sagittally-symmetric and -asymmetric trunk flexion movements. Specifically, decreased and asymmetric passive contributions to trunk movements were compensated with increases in the magnitude and duration of active trunk muscle responses. Such alterations in trunk passive and active neuromuscular responses may result from repetitive exposures to abnormal gait and movement subsequent to LLA, and may increase the risk for LBP in this population. [ABSTRACT FROM AUTHOR]

Leg stiffness is often computed from ground reaction force (GRF) registrations of vertical hops to estimate the force-resisting capacity of the lower-extremity during ground contact, with leg stiffness values incorporated in a spring-mass model to describe human motion. Individual biomechanical character-istics, including leg stiffness, were investigated in 40 healthy males. Our aim is to report and discuss the use of 13 different computational methods for evaluating leg stiffness from a double-legged repetitive hopping task, using only GRF registrations. Four approximations for the velocity integration constant were combined with three mathematical expressions, giving 12 methods for computing stiffness using double integrations. One frequency-based method that considered ground contact times was also trialled. The 13 methods thus defined were used to compute stiffness in four extreme cases, which were the stiffest, and most compliant, consistent and variable subjects. All methods provided different stiffness measures for a given individual, but the between-method variations in stiffness were consistent across the four atypical subjects. The frequency-based method apparently overestimated the actual stiffness values, whereas double integrations' measures were more consistent. In double integrations, the choice of the integration constant and mathematical expression considerably affected stiffness values, as variations during hopping were more or less emphasized. Stating a zero centre of mass position at take-off gave more consistent results, and taking a weighted-average of the force or displacement curve was more forgiving to variations in performance. In any case, stiffness values should always be accompanied by a detailed description of their evaluation methods, as our results demonstrated that computational methods affect calculated stiffness. [ABSTRACT FROM AUTHOR]