3D Motion Capture May Detect Spatiotemporal Changes in Pre-Reaching Upper Extremity Movements with and without a Real-Time Constraint Condition in Infants with Perinatal Stroke and Cerebral Palsy: A Longitudinal Case Series.

Perinatal stroke (PS), occurring between 20 weeks of gestation and 28 days of life, is a leading cause of hemiplegic cerebral palsy (HCP). Hallmarks of HCP are motor and sensory impairments on one side of the body-especially the arm and hand contralateral to the stroke (involved side). HCP is diagnosed months or years after the original brain injury. One effective early intervention for this population is constraint-induced movement therapy (CIMT), where the uninvolved arm is constrained by a mitt or cast, and therapeutic activities are performed with the involved arm. In this preliminary investigation, we used 3D motion capture to measure the spatiotemporal characteristics of pre-reaching upper extremity movements and any changes that occurred when constraint was applied in a real-time laboratory simulation. Participants were N = 14 full-term infants: N = six infants with typical development; and N = eight infants with PS (N = three infants with PS were later diagnosed with cerebral palsy (CP)) followed longitudinally from 2 to 6 months of age. We aimed to evaluate the feasibility of using 3D motion capture to identify the differences in the spatiotemporal characteristics of the pre-reaching upper extremity movements between the diagnosis group, involved versus uninvolved side, and with versus and without constraint applied in real time. This would be an excellent application of wearable sensors, allowing some of these measurements to be taken in a clinical or home setting.

Effects of Optimization Technique on Simulated Muscle Activations and Forces.

Two optimization techniques, static optimization (SO) and computed muscle control (CMC), are often used in OpenSim to estimate the muscle activations and forces responsible for movement. Although differences between SO and CMC muscle function have been reported, the accuracy of each technique and the combined effect of optimization and model choice on simulated muscle function is unclear. The purpose of this study was to quantitatively compare the SO and CMC estimates of muscle activations and forces during gait with the experimental data in the Gait2392 and Full Body Running models. In OpenSim (version 3.1), muscle function during gait was estimated using SO and CMC in 6 subjects in each model and validated against experimental muscle activations and joint torques. Experimental and simulated activation agreement was sensitive to optimization technique for the soleus and tibialis anterior. Knee extension torque error was greater with CMC than SO. Muscle forces, activations, and co-contraction indices tended to be higher with CMC and more sensitive to model choice. CMC's inclusion of passive muscle forces, muscle activation-contraction dynamics, and a proportional-derivative controller to track kinematics contributes to these differences. Model and optimization technique choices should be validated using experimental activations collected simultaneously with the data used to generate the simulation.

Gait, balance, and patient-reported outcomes during taxane-based chemotherapy in early-stage breast cancer patients.

BACKGROUND: Chemotherapy-induced peripheral neuropathy (CIPN) is a dose-limiting toxicity of several commonly used chemotherapy drugs including taxanes, vinca alkaloids, and platinum compounds. Development of CIPN is highly variable, both in self-reported symptoms and functional consequences, and can be severe enough to alter dose intensity. PURPOSE: To describe the natural histories of both patient-reported symptoms of CIPN and functional impairments in breast cancer patients undergoing taxane-based chemotherapy. METHODS: Thirty-three breast cancer patients (32 female/1 male; 47.8 ± 11.2 years; n = 17 stage II/n = 16 stage III) were enrolled. Patients completed self-reports of symptoms and function (e.g., EORTC QLQ-CIPN20) and objective measures of physical function (i.e., balance and gait testing) in an outpatient oncology clinic at five timepoints: (1) baseline-prior to starting chemotherapy, (2-4) before starting subsequent chemotherapy cycles, and (5) 1-3 months after receiving their last taxane infusion. RESULTS: Significant negative changes in both patient-reported outcomes and objective functional measures were observed. Decreased balance was observed after the first chemotherapy cycle (28% increase in medial-lateral excursion of the center of pressure, p = 0.016) and progressed with cumulative exposure (43% increase, p < 0.001). Patients also demonstrated slower walking speeds (5% decrease, p = 0.003) as they progressed through treatment. These functional deficits were mirrored with increased patient-reported symptom severity for all EORTC QLQ-CIPN20 subscales (all p < 0.05). CONCLUSION: This study longitudinally assessed patient-reported outcomes concurrently with balance and gait testing in patients undergoing taxane therapy. Taxane treatment was associated with the development of clinically relevant problems in both CIPN symptoms and patient function.

Do Neuromuscular Dentistry-Designed Mouthguards Enhance Dynamic Movement Ability in Competitive Athletes?

The purpose of this study was to examine the effect of a neuromuscular dentistry-designed mouthguard (NMDD) on dynamic movement ability. Forty-two competitive athletes (8 women, 21.9 ± 2.9 years, 66.8 ± 18.8 kg, 1.68 ± 0.11 m; 34 men, 22.8 ± 4.8 years, 77.4 ± 12.7 kg, 1.78 ± 0.08 m) with greater than 2 years' experience in their designated sport were enrolled in the study. Participants completed the Functional Movement Screen (FMS), modified Star Excursion Balance Test (mSEBT), and a single-leg landing (SLL) task. Each subject was tested with 3 separate mouthguard conditions in random order: (a) no mouthguard (NO), (b) over-the-counter boil-and-bite mouthguard (BB; Shockdoctor Gravity, (c) and an NMDD (Pure Power Elite). Data were analyzed using a repeated-measures analysis of variance for each variable. There were no differences between mouthguard conditions in each of the 7 individual components or composite FMS score (p > 0.05). No differences were seen in the anterior, posteromedial, or posterolateral movements of the mSEBT; overall composite score; or time-to-contact measurements (p > 0.05). The BB condition (2.16 Nm·kg) exhibited higher peak knee valgus moments (pKVM) on the right leg only when compared with the NMDD condition (1.95 Nm·kg; p = 0.003) but not the NO condition (2.09 Nm·kg; p = 0.7262) during the SLL task. No differences in pKVM were seen on the left leg (p = 0.324). In conclusion, an NMDD was not effective at enhancing or diminishing measures of dynamic movement ability compared with BB or NO conditions.

Physical Exam Risk Factors for Lower Extremity Injury in High School Athletes: A Systematic Review.

OBJECTIVE: A stated goal of the preparticipation physical evaluation (PPE) is to reduce musculoskeletal injury, yet the musculoskeletal portion of the PPE is reportedly of questionable use in assessing lower extremity injury risk in high school-aged athletes. The objectives of this study are: (1) identify clinical assessment tools demonstrated to effectively determine lower extremity injury risk in a prospective setting, and (2) critically assess the methodological quality of prospective lower extremity risk assessment studies that use these tools. DATA SOURCES: A systematic search was performed in PubMed, CINAHL, UptoDate, Google Scholar, Cochrane Reviews, and SportDiscus. Inclusion criteria were prospective injury risk assessment studies involving athletes primarily ages 13 to 19 that used screening methods that did not require highly specialized equipment. Methodological quality was evaluated with a modified physiotherapy evidence database (PEDro) scale. MAIN RESULTS: Nine studies were included. The mean modified PEDro score was 6.0/10 (SD, 1.5). Multidirectional balance (odds ratio [OR], 3.0; CI, 1.5-6.1; P < 0.05) and physical maturation status (P < 0.05) were predictive of overall injury risk, knee hyperextension was predictive of anterior cruciate ligament injury (OR, 5.0; CI, 1.2-18.4; P < 0.05), hip external:internal rotator strength ratio of patellofemoral pain syndrome (P = 0.02), and foot posture index of ankle sprain (r = -0.339, P = 0.008). CONCLUSIONS: Minimal prospective evidence supports or refutes the use of the functional musculoskeletal exam portion of the current PPE to assess lower extremity injury risk in high school athletes. Limited evidence does support inclusion of multidirectional balance assessment and physical maturation status in a musculoskeletal exam as both are generalizable risk factors for lower extremity injury.

Muscle Forces and Their Contributions to Vertical and Horizontal Acceleration of the Center of Mass During Sit-to-Stand Transfer in Young, Healthy Adults.

Sit-to-stand transfer is a common task that is challenging for older adults and others with musculoskeletal impairments. Associated joint torques and muscle activations have been analyzed two-dimensionally, neglecting possible three-dimensional (3D) compensatory movements in those who struggle with sit-to-stand transfer. Furthermore, how muscles accelerate an individual up and off the chair remains unclear; such knowledge could inform rehabilitation strategies. We examined muscle forces, muscleinduced accelerations, and interlimb muscle force differences during sit-to-stand transfer in young, healthy adults. Dynamic simulations were created using a custom 3D musculoskeletal model; static optimization and induced acceleration analysis were used to determine muscle forces and their induced accelerations, respectively. The gluteus maximus generated the largest force (2009.07 ± 277.31 N) and was a main contributor to forward acceleration of the center of mass (COM) (0.62 ± 0.18 m/s(2)), while the quadriceps opposed it. The soleus was a main contributor to upward (2.56 ± 0.74 m/s(2)) and forward acceleration of the COM (0.62 ± 0.33 m/s(2)). Interlimb muscle force differences were observed, demonstrating lower limb symmetry cannot be assumed during this task, even in healthy adults. These findings establish a baseline from which deficits and compensatory strategies in relevant populations (eg, elderly, osteoarthritis) can be identified.

Stride Leg Ground Reaction Forces Predict Throwing Velocity in Adult Recreational Baseball Pitchers.

Ground reaction forces produced during baseball pitching have a significant impact in the development of ball velocity. However, the measurement of only one leg and small sample sizes in these studies curb the understanding of ground reaction forces as they relate to pitching. This study aimed to further clarify the role ground reaction forces play in developing pitching velocity. Eighteen former competitive baseball players with previous high school or collegiate pitching experience threw 15 fastballs from a pitcher's mound instrumented to measure ground reaction forces under both the drive and stride legs. Peak ground reaction forces were recorded during each phase of the pitching cycle, between peak knee height and ball release, in the medial/lateral, anterior/posterior, and vertical directions, and the peak resultant ground reaction force. Stride leg ground reaction forces during the arm-cocking and arm-acceleration phases were strongly correlated with ball velocity (r2 = 0.45-0.61), whereas drive leg ground reaction forces showed no significant correlations. Stepwise linear regression analysis found that peak stride leg ground reaction force during the arm-cocking phase was the best predictor of ball velocity (r2 = 0.61) among drive and stride leg ground reaction forces. This study demonstrates the importance of ground reaction force development in pitching, with stride leg forces being strongly predictive of ball velocity. Further research is needed to further clarify the role of ground reaction forces in pitching and to develop training programs designed to improve upper extremity mechanics and pitching performance through effective force development.

Knee joint loading during lineman-specific movements in American football players.

Linemen are at high risk for knee cartilage injuries and osteoarthritis. High-intensity movements from squatting positions (eg, 3-point stance) may produce high joint loads, increasing the risk for cartilage damage. We hypothesized that knee moments and joint reaction forces during lineman-specific activities would be greater than during walking or jogging. Data were collected using standard motion analysis techniques. Fifteen NCAA linemen (mean ± SD: height = 1.86 ± 0.07 m, mass = 121.45 ± 12.78 kg) walked, jogged, and performed 3 unloaded lineman-specific blocking movements from a 3-point stance. External 3-dimensional knee moments and joint reaction forces were calculated using inverse dynamics equations. MANOVA with subsequent univariate ANOVA and post hoc Tukey comparisons were used to determine differences in peak kinetic variables and the flexion angles at which they occurred. All peak moments and joint reaction forces were significantly higher during jogging than during all blocking drills (all P < .001). Peak moments occurred at average knee flexion angles > 70° during blocking versus < 44° in walking or jogging. The magnitude of moments and joint reaction forces when initiating movement from a 3-point stance do not appear to increase risk for cartilage damage, but the high flexion angles at which they occur may increase risk on the posterior femoral condyles.

Landing ground reaction forces in figure skaters and non-skaters.

Researchers and clinicians have suggested that overuse injuries to the lower back and lower extremities of figure skaters may be associated with the repeated high impact forces sustained during jump landings. Our primary aim was to compare the vertical ground reaction forces (GRFs) in freestyle figure skaters (n = 26) and non-skaters (n = 18) for the same barefoot single leg landing on a force plate from a 20 cm platform. Compared with non-skaters, skaters exhibited a significantly greater normalised peak GRF (3.50 ± 0.47 × body weight for skaters vs. 3.13 ± 0.45 × body weight for non-skaters), significantly shorter time to peak GRF (81.21 ± 14.01 ms for skaters vs. 93.81 ± 16.49 ms for non-skaters), and significantly longer time to stabilisation (TTS) of the GRF (2.38 ± 0.07 s for skaters vs. 2.22 ± 0.07 s for non-skaters). Skaters also confined their centre of pressure (CoP) to a significantly smaller mediolateral (M-L) (25%) and anterior-posterior (A-P) (40%) range during the landing phase, with the position of the CoP located in the mid to forefoot region. The narrower and more forward position of the CoP in skaters may at least partially explain the greater peak GRF, shorter time to peak, and longer TTS. Training and/or equipment modification serve as potential targets to decrease peak GRF by distributing it over a longer time period. More comprehensive studies including electromyography and motion capture are needed to fully characterise the unique figure skater landing strategy.

Hip adductor activations during run-to-cut manoeuvres in compression shorts: implications for return to sport after groin injury.

Athletes at high risk of groin strains in sports such as hockey and soccer often choose to wear shorts with directional compression to aid in prevention of or recovery from hip adductor strains. Large, eccentric contractions are known to result in or exacerbate strain injuries, but it is unknown if these shorts have a beneficial effect on hip adductor muscle activity. In this study, surface electromyography (EMG) of the adductor longus and ground reaction force (GRF) data were obtained simultaneously on 29 healthy individuals without previous history of serious injury while performing unanticipated 45° run-to-cut manoeuvres in a laboratory setting wearing shorts with non-directional compression (control, HeatGear, Under Armour, USA) or shorts with directional compression (directional, CoreShort PRO, Under Armour, USA), in random order. Average adductor activity in the stance leg was significantly lower in the directional condition than in the control condition during all parts of stance phase (all P < 0.042). From this preliminary analysis, wearing directional compression shorts appears to be associated with reduced stance limb hip adductor activity. Athletes seeking to reduce demand on the hip adductors as they approach full return to activities may benefit from the use of directional compression shorts.

Anteromedial ridging of the femoral intercondylar notch: an anatomic study of 170 archival skeletal specimens.

PURPOSE: (1) To identify the relationship between anteromedial notch ridging, a recently identified non-contact anterior cruciate ligament injury risk factor, and patient demographics in a general population. (2) To characterize the symmetry of the femoral notch between knees. METHODS: The femoral notches of 170 non-arthritic archival skeletal specimens devoid of soft-tissue attachments (n = 79 females, 90 males, 34.3 ± 15.7 years) were measured for notch width, ridge thickness, and outlet stenosis due to ridging. Measurements were compared by race and sex by ANOVA, and Pearson correlations were calculated for all continuous measures. RESULTS: Percent stenosis was associated with increasing age (p < 0.001, r = 0.40). Ridge thickness was similar among men (2.7 ± 1.6 mm) and women (3.1 ± 1.5; n.s.). Women had narrower notches (16.0 ± 2.1 mm) and higher percent stenosis (19.6 ± 9.9 %) than men (p ≤ 0.001; men 19.3 ± 2.4 mm; 14.4 ± 8.7 %). African American men have narrower notches than Caucasian men (20.4 ± 2.5 vs. 18.7 ± 2.3 mm, respectively; p = 0.002) with no difference between women of both races (16.2 ± 2.5 vs. 15.8 ± 1.6 mm, respectively; n.s.). A positive association was observed between height and notch width among men only (18+ years men p = 0.004, r = 0.33; women n.s., r = 0.21). Finally, both total notch width and ridge thickness are symmetric between knees (p < 0.001; r = 0.98 and 0.93, respectively). CONCLUSIONS: Women have narrower femoral notches overall and also exhibit greater percent notch stenosis due to anteromedial ridging than men. Anteromedial ridging increases with age, suggesting progressive formation over time. Finally, both notch width and ridge thickness are highly symmetric between knees.

Quadriceps femoris strength and sagittal-plane knee biomechanics during stair ascent in individuals with articular cartilage defects in the knee.

CONTEXT: Few objective data are available regarding strength and movement patterns in individuals with articular cartilage defects (ACDs) of the knee. OBJECTIVES: To test the following hypotheses: (1) The involved limb of individuals with ACDs would demonstrate lower peak knee-flexion angle, peak internal knee-extension moment, and peak vertical ground-reaction force (vGRF) than the contralateral limb and healthy controls. (2) On the involved limb of individuals with ACDs, quadriceps femoris strength would positively correlate with peak knee-flexion angle, peak internal knee-extension moment, and peak vGRF. DESIGN: Cross-sectional. SETTING: Biomechanics research laboratory. PARTICIPANTS: 11 individuals with ACDs in the knee who were eligible for surgical cartilage restoration and 10 healthy controls. METHODS: Quadriceps femoris strength was quantified as peak isometric knee-extension torque via an isokinetic dynamometer. Sagittal-plane knee kinematics and kinetics were measured during the stance phase of stair ascent with 3-dimensional motion analysis. MAIN OUTCOME MEASURES: Quadriceps strength and knee biomechanics during stair ascent were compared between the involved and contralateral limbs of participants with ACD (paired t tests) and with a control group (independent-samples t tests). Pearson correlations evaluated relationships between strength and stair-ascent biomechanics. RESULTS: Lower quadriceps strength and peak internal knee-extension moments were observed in the involved limb than in the contralateral limb (P < .01) and the control group (P < .01). For the involved limb of the ACD group, quadriceps femoris strength was strongly correlated (r = .847) with involved-limb peak internal knee-extension moment and inversely correlated (r = -.635) with contralateral peak vGRF. CONCLUSIONS: Individuals with ACDs demonstrated deficits in quadriceps femoris strength with associated alterations in movement patterns during stair ascent. The results of this study are not comprehensive; further research is needed to understand the physiological characteristics, activity performance, and movement quality in this population.

Neuromuscular and trunk control mediate factors associated with injury in fatigued runners.

This study aimed to determine how fatigue affects factors associated with injury, neuromuscular activity, and control in recreational runners. Previously identified injury risk factors were defined as peak vertical instantaneous loading rates (pVILR) for tibial stress fracture (TSF) and peak hip adduction (pHADD) for patellofemoral pain syndrome and iliotibial band syndrome. Kinematics, kinetics, and electromyography data were collected from 11 recreational runners throughout a fatiguing run. Three trials were collected in the first and final minutes of the run. Coactivation was quantified about the knee and ankle for the entire stance phase and anticipatory, weight acceptance (WA), and propulsion sub-phases of stance. Trunk control was quantified by the peak mediolateral lean, peak forward lean, and flexion range of motion (ROM). There were significant increases in pHADD and pVILR when fatigued. Significant decreases in coactivation around the knee were found over the entire stance phase, in the anticipatory phase, and WA phase. Coactivation decreased about the ankle during WA. Lateral trunk lean significantly increased when fatigued, but no significant changes were found in flexion ROM or lean. Mediation analyses showed changes in ankle coactivation during WA, and lateral trunk lean are significant influences on pVILR, a measure associated with TSF. Fatigue-induced adaptations of decreasing ankle coactivation during WA and increased lateral trunk lean may increase the likelihood of TSF. In this study, a fatiguing run influenced changes in control in recreational runners. Further investigation of causal fatigue-induced injuries is necessary to better understand the effects of coactivation and trunk control.

Models of Video Feedback for Youth Athletes Performing an American Football Tackle.

CONTEXT: Video feedback is an expeditious method for improving athlete safety when performing activities with an inherent risk of injury. Providing appropriate and validated feedback during tackling training in American football may be a mechanism for athletes to learn safe tackling performance. OBJECTIVE: To determine the effect of video feedback in the instruction of tackling form. DESIGN: Controlled laboratory study. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 32 youth football athletes (28 boys, 4 girls; age = 11.8 ± 0.8 years) participated in 1 day of training. Of those, 14 participants completed 2 additional days of training and a 48-hour retention and transfer test. INTERVENTION(S): Video feedback using self as model, expert as model, combined self and expert model, and oral feedback to promote safe tackling performance in a laboratory environment. MAIN OUTCOME MEASURE(S): Shoulder extension, cervical extension, trunk angle, pelvis height, and step length by training block and over time. RESULTS: For the 1-day training group, main effects for time were observed for shoulder extension (P < .01), cervical extension (P = .01), pelvis height (P < .01), and step length (P < .01), with better performance for pelvis height and step length after combined feedback. For the 3-day training group, main effects of time were identified in pelvis height (P < .01) and step length (P < .01), with combined feedback showing better performance than other methods in shoulder extension and pelvis height. Combined feedback resulted in better performance compared with its component parts and oral feedback alone. In the combined model, participants viewed both their performance and the expert model, enabling them to see the difference between current and required performance. CONCLUSIONS: Combined feedback may be superior to other forms of feedback in improving movement performance. This effect can be generalized across disciplines that provide instruction and feedback in movement.

Individuals with a ventral hernia who report moderate to high fear have worse functional performance than those with low fear.

PURPOSE: Ventral hernia repairs (VHR) are performed to restore the integrity of the abdominal wall. Fear of movement, or kinesiophobia, may develop in patients with ventral hernia due to pain and functional impairments, however it has not yet been objectively measured in this patient population. The purpose of this study was to test the hypothesis that in patients with ventral hernia awaiting surgical repair, higher levels of kinesiophobia would be associated with poorer mobility, abdominal core function, and quality of life. METHODS: Seventy-seven participants scheduled for ventral hernia repair were enrolled as part of an ongoing randomized controlled trial (NCT05142618). The Tampa Scale of Kinesiophobia (TSK-11) is an 11-item questionnaire that asks about fear of movement and physical activity restriction. Participants were split into groups based on their TSK-11 score (minimal, low, moderate to high). Primary outcome measures included the five-time sit-to-stand (5xSTS), Quiet Unstable Sitting Test (QUeST), and the Hernia-Related Quality-of-Life (HerQLeS) survey. A one-way ANOVA with a Bonferroni correction compared QUeST, 5xSTS, and HerQLes results between groups. RESULTS: Groups were significantly different on 5xSTS (minimal: 11.4 ± 2.6 s, low: 13.8 ± 3.1 s, moderate to high: 17.8 ± 9.8 s; p = 0.001) and HerQLes (minimal: 58.0 ± 27.8, low: 49.4 ± 22.0, moderate to high: 30.6 ± 25.3; p = 0.003) but not QUeST (minimal: - 2.8 ± 2.5, low: - 6.8 ± 10.0, moderate to high: - 5.5 ± 5.0; p = 0.16). CONCLUSION: Individuals with moderate to high kinesiophobia have worse pre-operative performance-based (5xSTS) and self-reported (HerQLes) function and quality of life than those with minimal and low kinesiophobia. Future research should examine the influence of kinesiophobia on post-operative outcomes as it may be a potent target for rehabilitation.

Lumbopelvic neuromuscular training and injury rehabilitation: a systematic review.

OBJECTIVE: The aim of this systematic review was to assess the evidence for lumbopelvic neuromuscular training (LNMT) in individuals after musculoskeletal (MSK) injury. DATA SOURCES: A literature search of PubMed and EMBASE databases was performed for English studies from January 1990 to March 2012. Search terms including and related to trunk, core, stability, injury, and LNMT were used. STUDY SELECTION: All studies directly involving LNMT for MSK injuries were reviewed by 2 authors. These articles were assessed based on the inclusion criteria and if appropriate selected for further analysis. Expert opinion, review articles, and articles involving non-MSK injuries were excluded. Four authors then scored the selected articles for methodological quality. A total of 2312 articles were initially identified. Twenty-nine articles met the inclusion criteria for review and were divided into categories of lower extremity (LE), lumbar, and upper extremity (UE). No trials involving the UE met the inclusion criteria. DATA EXTRACTION: Data including subject demographics (age, height, weight, gender, etc), injury type, intervention type, and outcome measurements were extracted from the relevant articles. A variety of baseline and follow-up scores were extracted including pain levels, patient satisfaction, disability questionnaires, and other functional outcomes. DATA SYNTHESIS: Two out of 3 LE randomized controlled trials (RCTs) and 9/26 lumbar RCTs were rated with high methodological quality based on the scoring system described by van Tulder et al. The average quality score for the LE RCTs was 6.3 (range = 4-9) and for the lumbar RCTs was 5.1 (range = 2-9). The evidence for the effectiveness of the 3 LE studies was rated as conflicting, whereas 24 lumbar studies demonstrated moderate-to-strong evidence. Unfortunately, heterogeneity of populations, interventions, and outcomes precluded a quantitative meta-analysis and specific clinical recommendations. CONCLUSIONS: High-quality evidence is lacking to make specific clinical recommendations for or against the use of LNMT in the rehabilitation of individuals after MSK injury. Based on this review, future research should focus on well-defined, homogeneous populations, interventions specifically addressing neuromuscular activation of the lumbopelvic musculature, patient-specific clinical outcomes, measures of motor control, biomechanics, and return to specific activities.

Knee joint kinetics in relation to commonly prescribed squat loads and depths.

Controversy exists regarding the safety and performance benefits of performing the squat exercise to depths beyond 90° of knee flexion. Our aim was to compare the net peak external knee flexion moments (pEKFM) experienced over typical ranges of squat loads and depths. Sixteen recreationally trained men (n = 16; age, 22.7 ± 1.1 years; body mass, 85.4 ± 2.1 kg; height, 177.6 ± 0.96 cm; mean ± SEM) with no previous lower-limb surgeries or other orthopedic issues and at least 1 year of consistent resistance training experience while using the squat exercise performed single-repetition squat trials in a random order at squat depths of above parallel, parallel, and below parallel. Less than 1 week before testing, 1RM values were found for each squat depth. Subsequent testing required the subjects to perform squats at the 3 depths with 3 different loads: unloaded, 50% 1RM, and 85% 1RM (9 total trials). Force platform and kinematic data were collected to calculate pEKFM. To assess the differences among loads and depths, a 2-factor (load and depth) repeated measures analysis of variance with significance set at the p < 0.05 level was used. Squat 1RM significantly decreased 13.6% from the above-parallel to the parallel squat and another 3.6% from the parallel to the below-parallel squat (p < 0.05). Net peak external knee flexion moments significantly increased as both squat depth and load were increased (p ≤ 0.02). Slopes of pEKFM were greater from unloaded to 50% 1RM than when progressing from 50% to 85% 1RM (p < 0.001). The results suggest that typical decreases in squat loads used with increasing depths are not enough to offset increases in pEKFM.

Estimating marksmanship performance during walking while maintaining weapon aim.

Marksmanship performance while moving is a critical skill among tactical athletes due to the high demands of their occupational duties. Qualifications for dynamic marksmanship performance are not standardized across tactical athlete groups, which may limit comprehensive assessment of tactical athlete performance for situational awareness and adaptability to an unpredictable environment. Although static marksmanship performance provides foundational information on skills and level of ability, research is lacking on factors that influence dynamic marksmanship performance to best prepare tactical athletes for duties. The purpose of this study was to identify whether static marksmanship performance, speed of movement, load carriage, and biomechanical factors while 'shooting on the move' influenced dynamic marksmanship performance. Twenty-four male tactical athletes (22 active-duty Army Soldiers, two civilian SWAT operators; age: 23.83 ± 5.47 years; height: 1.80 ± 0.08 m; weight: 81.04 ± 7.87 kg) participated; final analyses did not include data from the two civilian operators to maintain sample homogeneity. Tactical athletes completed static and dynamic ('shoot on the move') marksmanship tasks under three load conditions: (1) no load (NL), (2) half kit (HK) of 11.34 kg, and (3) full kit (KIT) of 22.68 kg. Dynamic marksmanship was completed under three speed conditions: (1) self-selected slow speed, (2) standard speed, and (3) self-selected fast speed. Hip, knee, and ankle kinematics were collected via wireless inertial measurement units. Spatiotemporal parameters were collected via optical detection system. Marksmanship performance (accuracy) was collected via open-air acoustic target scoring and mean radial error (MRE) was calculated for both static and dynamic marksmanship tasks. Linear mixed-effects models were fit with dynamic MRE as the outcome variable with fixed effects of static MRE, load condition, speed condition, kinematics, and spatiotemporal parameters, adjusting for body mass. Alpha level was set a priori at p ≤ 0.10. The final statistical model included fixed effects of static MRE, load condition, speed condition, and time spent in double limb support. Static MRE (p < 0.01) and time spent in double limb support (p = 0.01) were significant factors. For each 1 cm increase in static MRE there was a 0.66 cm increase in dynamic MRE. For every 1% increase in time spent in double limb support while 'shooting on the move' there was a 0.13 cm increase in dynamic MRE. Findings from this study highlight that tactical athletes who have larger static stance MRE and spend a longer time in double limb support during a gait cycle exhibit an increase in MRE during 'shoot on the move' trials. Overall, dynamic shooting accuracy is not affected by lower extremity joint angles, load carriage, or speed of movement. Although strong relationships are known between gait speed, load, and lower extremity kinematics, the differences in tactical gait compared to normal gait and multi-task paradigm that likely favors marksmanship accuracy seem to present novel movement characteristics unique to occupational gait. Further investigation is warranted to identify other potential factors that may improve or worsen dynamic marksmanship performance.

Task-Related Differences in End-Point Kinematics in School-Age Children with Typical Development.

Understanding whether and how children with typical development adapt their reaches for different functional tasks could inform a more targeted design of rehabilitation interventions to improve upper extremity function in children with motor disabilities. This prospective study compares timing and coordination of a reach-to-drink, reach-to-eat, and a bilateral reaching task in typically developing school-aged children. Average speed, straightness, and smoothness of hand movements were measured in a convenience sample of 71 children, mean age 8.77 ± 0.48 years. Linear mixed models for repeated measures compared the variables by task, phases of the reach, task x phase interactions, and dominant versus non-dominant hands. There were significant main effects for task and phase, significant task x phase interactions (p < 0.05), and a significant difference between the dominant and non-dominant hand for straightness. Hand movements were fastest and smoothest for the reach-to-eat task, and least straight for the bilateral reaching task. Hand movements were also straighter in the object transport phases than the prehension and withdrawal phases. These results indicate that children with typical development change their timing and coordination of reach based on the task they are performing. These results can inform the design of rehabilitation interventions targeting arm and hand function.

Use of accelerometers and inertial measurement units to quantify movement of tactical athletes: A systematic review.

The dynamic work environments of tactical athletes are difficult to replicate in a laboratory. Accelerometers and inertial measurement units provide a way to characterize movement in the field. This systematic review identified how accelerometers and inertial measurement units are currently being used to quantify movement patterns of tactical athletes. Seven research and military databases were searched, producing 26,228 potential articles with 78 articles included in this review. The articles studied military personnel (73.1%), firefighters (19.2%), paramedics (3.8%), and law enforcement officers (3.8%). Accelerometers were the most used type of sensor, and physical activity was the primarily reported outcome variable. Seventy of the studies had fair or poor quality. Research on firefighters, emergency medical services, and law enforcement officers was limited. Future research should strive to make quantified movement data more accessible and user-friendly for non-research personnel, thereby prompting increased use in tactical athlete groups, especially first responder agencies.