Preliminary Evaluation of a Questionnaire to Measure Program-Level Sense of Belonging Among Student Physical Therapists.

INTRODUCTION: A greater sense of belonging has been found to correspond with better academic performance/motivation, retention, and general mental well-being among college students. As a result, it is important to be able to meaningfully assess student physical therapists' sense of belonging. REVIEW OF LITERATURE: While there are questionnaires available to assess sense of belonging at the university level, it is also important to be able to assess students' sense of belonging in a narrower context, such as within their program of study. The purpose of this study was to develop and evaluate a program-specific tool, referred to as the Program Sense of Belonging (ProSB) questionnaire, that could be used to assess sense of belonging among student physical therapists. As part of this study, we examined the internal structure of the ProSB questionnaire items and assessed internal consistency. SUBJECTS: One hundred twenty-four student physical therapists from 2 different physical therapist education programs completed the ProSB questionnaire. METHODS: We conducted an exploratory factor analysis to examine the internal structure of the ProSB questionnaire and examined Cronbach's alpha to assess the internal consistency of the items associated with each retained factor. RESULTS: For the final 10-item version of the ProSB questionnaire, 2 factors were retained, which explained 57.5% of the variance (factor 1 = 30.9%, factor 2 = 26.6%). The 5 items that loaded on factor 1 were related to "social acceptance," while the 5 items that loaded on factor 2 were related to "valued competence." Both subscales exhibited acceptable levels of internal consistency (Cronbach's alpha ≥0.84). DISCUSSION: The ProSB questionnaire appears to capture different dimensions of student physical therapists' sense of belonging (social acceptance, valued competence) at the program level. CONCLUSION: Based on our preliminary findings, the ProSB questionnaire appears to be a valid tool for assessing program-level sense of belonging among student physical therapists.

Inter-limb kinetic asymmetries during sit-to-stand performance persist following unilateral total knee arthroplasty: A systematic review and meta-analysis.

BACKGROUND: Kinetic asymmetries during sit-to-stand have been consistently observed early after total knee arthroplasty; however, the longer-term outcomes are less clear. The purpose of this systematic review and meta-analysis was to analyze the results of studies examining inter-limb kinetic symmetry during sit-to-stand performance among individuals who were at least one-year post unilateral total knee arthroplasty. METHODS: PubMed, SPORTDiscus, CINAHL, and Health Source databases were searched. Studies were included if they were published in a peer-reviewed journal, included subjects who had undergone unilateral total knee arthroplasty at least one-year prior, and examined vertical ground reaction forces and/or knee extension moments for the involved and uninvolved limbs during sit-to-stand performance. Data were transformed into a limb symmetry index, which expressed the ratio of the peak forces/moments for the involved limb, relative to the uninvolved limb (1.0 reflects perfect symmetry). These ratios were meta-analyzed using the ratio of means method. FINDINGS: Seven studies were deemed eligible for inclusion. Ground reaction force data was pooled from seven studies and knee extension moment data was pooled from two studies. For the peak vertical ground reaction forces, the pooled limb symmetry index was 0.96 (CI95% = [0.93, 0.99]). For the peak knee extension moments, the pooled limb symmetry index was 0.91 (CI95% = [0.84, 0.98]). In both cases this reflects greater limb/knee loading for the uninvolved limb, relative to the involved limb. INTERPRETATION: Asymmetries in limb/knee loading persist beyond the one-year post-operative period following total knee arthroplasty, potentially contributing to degenerative changes for the uninvolved limb.

Comparison of Impact Accelerations During Performance of Common Ballet Maneuvers: A Pilot Study.

INTRODUCTION: Ballet landings produce accelerations that are transmitted proximally up the kinetic chain. If overly excessive/repetitive, these "shocks" to the lower body may contribute to overuse injury. The shocks imposed by different ballet maneuvers are largely unknown at this time, making it difficult to appreciate the physical stresses associated with different maneuvers. Therefore, the purpose of this study was to compare the impact accelerations associated with different common ballet maneuvers. METHODS: As part of this study, 11 adolescent ballet dancers performed 9 different common ballet maneuvers: (1) glissade, (2) pas de chat, (3) petit jeté, (4) petit assemblé, (5) grand assemblé, (6) grand jeté, (7) saut de chat, (8) changement, and (9) entrechat quatre. An inertial sensor secured to the pelvis was used to record the peak resultant acceleration during landings ("impact acceleration"). A Friedman test was conducted to compare impact accelerations across the maneuvers and Wilcoxon signed-rank tests were conducted as pairwise comparisons. RESULTS: The omnibus test indicated that there were differences in impact accelerations among the maneuvers (P < .001). In general, the glissade (2.08 ± 0.47g), pes de chat (2.33 ± 0.23g), petit jeté (2.42 ± 0.29g), and petite assemblé (2.54 ± 0.47g) tended to be the lower impact maneuvers; the grand assemblé (2.90 ± 0.41g), grand jeté (2.99 ± 0.33g), and saut de chat (3.13 ± 0.54g) tended to be the more moderate impact maneuvers; and the changement (4.10 ± 0.48g) and entrechat quatre (4.32 ± 0.52g) tended to be higher impact maneuvers. CONCLUSION: These findings may provide clinicians and dance instructors with greater insight regarding the physical stresses imposed by different ballet maneuvers.

Predicting First-Time National Physical Therapy Examination Performance for Graduates of an Entry-Level Physical Therapist Education Program.

INTRODUCTION: The National Physical Therapy Examination (NPTE) is a standardized examination designed to assess competence after graduation from an entry-level physical therapist education program. REVIEW OF LITERATURE: Previous studies have identified applicant and student variables that are related to NPTE performance, with applicant variables reflecting performance before admission and student variables reflecting performance after admission. However, there are very few articles describing how these variables can be combined to predict NPTE performance. The purpose of this study was to develop, evaluate, and describe models to predict first-time NPTE scores and NPTE outcomes (pass vs fail), based on various applicant and student variables related to academic performance. SUBJECTS: Pre- and postadmission data and NPTE scores were recorded for 185 individuals who graduated from an entry-level physical therapist education program. METHODS: Multiple linear regression was used to develop a model to predict NPTE scores, and binary logistic regression was used to develop a model to predict NPTE outcomes (pass vs fail). RESULTS: A model including undergraduate prerequisite grade point average, grade point average in basic science courses taken during the program, and comprehensive examination scores combined to explain 30.9% of the variance in NPTE scores and accurately predicted NPTE outcomes (pass vs fail) 81.1% of the time. DISCUSSION: In general, our findings support the notion that prediction of NPTE performance should be based on a combination of applicant and student variables. The models described in this article could be used to identify students who may be likely to struggle on the NPTE, making it possible to provide additional support to these students. CONCLUSION: Various applicant and student variables related to academic performance can be combined to predict NPTE performance. The results of this study provide a framework for programs interested in applying models to predict NPTE performance.

The Effects of Cadence Manipulation on Joint Kinetic Patterns and Stride-to-Stride Kinetic Variability in Female Runners.

Altering running cadence is commonly done to reduce the risk of running-related injury/reinjury. This study examined how altering running cadence affects joint kinetic patterns and stride-to-stride kinetic variability in uninjured female runners. Twenty-four uninjured female recreational runners ran on an instrumented treadmill with their typical running cadence and with a running cadence that was 7.5% higher and 7.5% lower than typical. Ground reaction force and kinematic data were recorded during each condition, and principal component analysis was used to capture the primary sources of variability from the sagittal plane hip, knee, and ankle moment time series. Runners exhibited a reduction in the magnitude of their knee extension moments when they increased their cadence and an increase in their knee extension moments when they lowered their cadence compared with when they ran with their typical cadence. They also exhibited greater stride-to-stride variability in the magnitude of their hip flexion moments and knee extension moments when they deviated from their typical running cadence (ie, running with either a higher or lower cadence). These differences suggest that runners could alter their cadence throughout a run in an attempt to limit overly repetitive localized tissue stresses.

Female Athletes Exhibit Greater Trial-to-Trial Coordination Variability When Provided with Instructions Promoting an External Focus.

The purpose of this study was to examine how instructions promoting different attentional foci influence joint coordination patterns and trial-to-trial coordination variability during landing. Sixteen females performed drop landings with their typical technique (baseline) and after receiving instructions promoting an internal focus and an external focus. The coordination patterns, and trial-to-trial coordination variability, of the sagittal plane hip-knee, hip-ankle, and knee-ankle angle pairings were compared across conditions. While there was no difference in the joint coordination patterns among the conditions, subjects exhibited greater hip-ankle and knee-ankle trial-to-trial coordination variability for the external focus condition, vs. the baseline and internal focus conditions, which may help to explain the improved motor learning outcomes for athletes who train with an external focus.

The Effects of Increasing Cognitive Load on Support Limb Kicking Mechanics in Male Futsal Players.

Our objective was to examine the effects of cognitive load on support limb mechanics during a futsal kicking task. Twenty-one male futsal players completed kicks of a stationary ball without a secondary task (baseline), as well as kicks where cognitive load was increased by including a secondary cognitive task (dual-task) and requiring tracking of ball movement before the kick (pass). The athletes demonstrated less hip and knee flexion, higher loading rates, greater frontal and sagittal plane knee loading, and greater knee abduction for the dual-task condition, vs. baseline. They also demonstrated less knee flexion, higher loading rates, greater sagittal plane knee loading, and greater knee abduction for the pass condition, vs. baseline. It appears that cognitive load influences kicking mechanics.

The effects of incremental changes in rucksack load on lower extremity joint Kinetic patterns during ruck marching.

Injuries are often attributed to ruck marching. Therefore, it is important to examine how load carriage influences gait mechanics. The purpose of this study was to examine how subtle changes in rucksack load influence joint torque patterns during marching. Fourteen Army ROTC cadets marched with light, moderate, and heavy rucksack loads. Kinetic and kinematic data were recorded via an instrumented treadmill and motion capture system and principal component analysis was used to analyse the joint torque waveforms. Cadets exhibited moderate-large increases in knee extension torques during early stance (effect sizes ≥0.45) and small-moderate increases in ankle plantarflexion torques during push off (effect sizes ≥0.23) with each incremental increase in rucksack load. The lighter load also resulted in lower hip extension torques during early stance and flexion torques during late stance, vs. the moderate and heavier loads (effect sizes ≥0.23). It appears that subtle changes in rucksack load influence marching mechanics. Practitioner Summary: The purpose of this study was to examine how relatively subtle changes in rucksack load influence marching mechanics. Army ROTC cadets marched with relatively light, moderate, and heavy rucksack loads. Our results indicate that even subtle changes in rucksack load influence joint torque patterns of the hip, knee, and ankle. Abbreviations: ROTC: reserve officer training corps; RoF: rating-of-fatigue; PC: principal component; ICC: intraclass correlation coefficient; ES: effect size.

Post-Trial Feedback Alters Landing Performance in Adolescent Female Athletes Using a Portable Feedback System.

BACKGROUND: Post-performance verbal and visual feedback based on data collected via lab-based instruments have been shown to improve landing patterns related to non-contact ACL injury. Biomechanical methods are often complex, difficult to transport and utilize in field settings, and costly, which limits their use for injury prevention. Developing systems that can readily provide feedback outside of the lab setting may support large scale use of feedback training for ACL injury prevention. PURPOSE/HYPOTHESIS: The purpose of this study was to investigate the effectiveness of a single training session using a custom portable feedback training system that provides performance cues to promote changes in impact kinetics and lower extremity position during landing in female athletes. STUDY DESIGN: Repeated measures. METHODS: One hundred fifty female athletes (ages 13-18 years old) landed from a 50 cm platform with and without feedback related to vertical ground reaction force (vGRF), vGRF symmetry and lower extremity position. Feedback was provided via a portable, low-cost system that included two custom-built force plates interfaced with a digital camera. Each athlete performed six pre-test trials followed by two blocks of six trials where they received visual feedback from the training system and individualized verbal cues from an investigator. Following training blocks, athletes completed six post-test trials without feedback and then six dual-task trials where a ball was randomly thrown to the performer during the landing (transfer task). vGRF and knee to ankle (K:A) separation ratio were measured and the average responses were reported for each trial block. RESULTS: Differences in vGRF between baseline, post-test and transfer task trial blocks were observed (F(2,298)=181.68, p < .0001). Mean (SD) peak vGRF (body weight) were 4.43 (0.90), 3.28 (0.61), and 3.80 (0.92), respectively. Differences in K:A ratio between baseline, post-test and transfer task trial blocks were shown (F(2,298)=68.47, p < .0001). Mean (SD) K:A ratio were 0.87 (0.21), 0.98 (0.19), and 0.92 (0.19), respectively. CONCLUSION: A portable feedback system may be effective in reducing peak vGRFs and promoting a more desirable K:A ratio during landing and transfer task landing in adolescent female athletes. LEVEL OF EVIDENCE: 3b.

Quantifying step length using two-dimensional video in individuals with Parkinson's disease.

Individuals with Parkinson's disease demonstrate a shorter step length compared to individuals without the disorder, which may place them at greater risk for falls. As a result, rehabilitation professionals often attempt to increase or maintain step length in this population. The ability to quantify step length may be useful for tracking changes or identifying individuals who may be at risk for a fall. However, there are few approaches to precisely/directly measure step length that are feasible for clinical use. The purposes of this study were to evaluate the reliability of step length measurements from two-dimensional (2D) video in individuals with Parkinson's disease and to compare the step lengths of individuals with/without a recent history of falls. A video camera recorded 24 individuals with Parkinson's disease as they walked at a comfortable pace. Step length measurements from the video demonstrated excellent intra- and inter-rater reliability (intraclass correlation coefficients greater than 0.90). In addition, individuals with Parkinson's disease who had experienced a fall within the previous year demonstrated shorter step lengths compared to individuals who had not experienced a recent fall. The ability to quantify step length from 2D video could be a useful tool when managing patients with Parkinson's disease.

THE INFLUENCE OF ATTENTIONAL FOCUS ON LANDING STIFFNESS IN FEMALE ATHLETES: A CROSS-SECTIONAL STUDY.

BACKGROUND: Anterior cruciate ligament injury prevention often involves instructing athletes to reduce landing stiffness. Instructions promoting an external focus appear to result in superior motor performance for a wide range of tasks; however, the effect of attentional focus on landing stiffness has not been examined. HYPOTHESIS/PURPOSE: The purpose of this study was to compare the influence of instructions promoting an internal focus vs. those promoting an external focus on landing stiffness. It was hypothesized that both types of instructions would reduce landing stiffness vs. landings performed prior to instruction. It was also hypothesized that participants would demonstrate a greater reduction in landing stiffness when provided with instructions promoting an external focus. STUDY DESIGN: Cross-sectional, quasi-experimental. METHODS: Sixteen female athletes (basketball, soccer, volleyball) completed drop landings while force and kinematic data were collected. Participants first performed drop landings with their typical technique (baseline). They then received instructions promoting an internal focus and an external focus before performing additional drop landings. Peak force, time-to-peak force, leg stiffness, and hip, knee, and ankle sagittal plane angles were analyzed. RESULTS: Both types of instructions resulted in lower landing forces, less leg stiffness, and greater hip and knee flexion versus at baseline. However, athletes demonstrated more knee flexion at the time of the peak force (59.4 ± 9.6 ° vs. 56.0 ± 9.5 °) and less leg stiffness (69.5 ± 17.9 Nkg-1/m vs. 84.0 ± 38.1 Nkg-1/m) when provided with instructions promoting an external focus, compared to when they were provided with instructions promoting an internal focus. CONCLUSION: Instructions promoting an external focus appear to result in a greater reduction in landing stiffness. Clinicians should consider providing instructions promoting an external focus when training athletes to reduce lower extremity stiffness during drop landings. The findings from this study may help to inform clinicians involved in movement pattern re-training for female athletes. LEVEL OF EVIDENCE: Level 3b.

Neuromuscular training improves knee proprioception in athletes with a history of anterior cruciate ligament reconstruction: A randomized controlled trial.

BACKGROUND: Athletes exhibit deficits in knee proprioception following anterior cruciate ligament reconstruction. Neuromuscular training programs improve knee proprioception in uninjured athletes; however, the effects on knee proprioception in athletes who have undergone anterior cruciate ligament reconstruction is not well understood. The purpose of this study was to examine the effects of a neuromuscular training program on knee proprioception in athletes who have returned to sport following anterior cruciate ligament reconstruction. METHODS: Twenty-four male athletes, who had undergone anterior cruciate ligament reconstruction within the previous 6-12 months and returned to sport, participated in this randomized controlled trial. Athletes were randomly allocated to an experimental group (n = 12) that took part in an 8-week neuromuscular training program or a control group (n = 12) that simply continued their typical training routine. Knee position sense was assessed at baseline and after the 8-week period (post-testing). One-way analysis of covariance, with baseline performance included as a covariate, was used to compare knee position sense errors for the reconstructed limbs of the experimental and control groups at the post-testing time point. FINDINGS: Knee position sense errors decreased by 51.7% for the experimental group and only 4.4% for the control group over the 8-week period. As a result, the experimental group demonstrated lower knee position sense errors, compared to the control group, at the post-testing time point (P < .001). INTERPRETATION: Athletes with a history of anterior cruciate ligament reconstruction may benefit from participation in a neuromuscular training program, even after completing post-operative rehabilitation.

Real-time visual feedback reduces patellofemoral joint forces during squatting in individuals with patellofemoral pain.

BACKGROUND: Elevated patellofemoral joint forces appear to contribute to the development of patellofemoral pain. As a result, treatment of patellofemoral pain often includes movement retraining intended to reduce patellofemoral joint forces. Real-time visual feedback has been shown to be effective for retraining running kinematics; however, we are not aware of a previous study that has examined the influence of real-time visual feedback on patellofemoral joint mechanics during a squat. METHODS: Twenty individuals with patellofemoral pain completed squats before (baseline) and immediately after (post-feedback) completing a real-time visual feedback training session. During the session, participants received visual feedback related to their patellofemoral joint forces (estimated via a musculoskeletal model) during squatting and were asked to alter their movement pattern to minimize these forces. Patellofemoral joint forces and hip, knee, and ankle joint mechanics were compared for the baseline and post-feedback trials in order to examine how feedback influenced squat performance. FINDINGS: Participants demonstrated a 14.4% reduction in patellofemoral joint forces following the feedback session. They appeared to achieve this reduction in patellofemoral joint forces by squatting with less knee flexion (97.26 ± 17.11° vs. 102.96 ± 16.55°) and lower knee extension moments (0.10 ± 0.02 Nm/bodyweight vs. 0.11 ± 0.02 Nm/bodyweight) and quadriceps forces (4.06 ± 0.87 bodyweights vs. 4.67 ± 0.98 bodyweights). INTERPRETATION: Real-time visual feedback appears to be effective for reducing patellofemoral joint forces during squatting in individuals with patellofemoral pain. As a result, training of this nature may be beneficial when treating patellofemoral pain.

The influence of fatigue on decision-making in athletes: a systematic review.

A potential challenge associated with sports is that athletes must often perform the cognitive processing associated with decision-making (i.e., movement selection) when fatigued. The purpose of this systematic review was to summarise studies that have analysed the extent to which fatigue influences the effects of decision-making on lower extremity mechanics during execution of common sports manoeuvres. We specifically focused on mechanics associated with ACL injury risk. Reviewers searched the PubMed, SPORTDiscus, CINAHL and Web of Science databases. The search identified 183 unique articles. Five of these articles met our eligibility criteria. Two of the studies incorporated fatigue protocols where athletes progressed to exhaustion and found that the effects of decision-making on mechanics were more pronounced with fatigue. The nature of the results appears to indicate that fatigue may compromise an athlete's cognitive processing in a manner that diminishes their ability to control movement when rapid decision-making is required. However, three subsequent studies utilised fatigue protocols designed to mimic sports participation and found that fatigue did not influence the effects of decision-making on mechanics. In general, these findings appear to indicate that fatigue may only affect the cognitive processing associated with decision-making when athletes approach a state of exhaustion.

Exploring the potential utility of a wearable accelerometer for estimating impact forces in ballet dancers.

Excessive forces and/or loading rates during landing may place ballet dancers at risk for overuse injury. The ability to estimate and monitor the landing forces of ballet dancers could help to improve injury prevention and rehabilitation; however, force platforms are not conducive to testing outside of a laboratory. Fortunately, it may be possible to indirectly assess landing forces via a wearable accelerometer. The purposes of this study were to examine the relationship between impact accelerations, recorded via a pelvis-worn accelerometer, and the peak forces and loading rates during performance of a common ballet manoeuvre, and to examine if a wearable accelerometer is sensitive to fatigue-related changes in landing forces. Fifteen ballet dancers continuously performed a ballet manoeuvre until self-determined exhaustion while impact accelerations and landing forces were simultaneously recorded using an accelerometer and force platforms. We observed very strong, positive relationships between the impact accelerations and the peak forces and loading rates during the landings. In addition, the changes in impact accelerations with fatigue paralleled the changes in the peak forces and loading rates. As a result, it appears that a wearable accelerometer could be used to estimate and monitor landing forces in ballet dancers.

Training rugby athletes with an external attentional focus promotes more automatic adaptions in landing forces.

Training to reduce landing forces is a common component of anterior cruciate ligament injury prevention programmes. The purpose of this study was to compare the effects of training incorporating instructions promoting an internal versus external attentional focus on landing forces in adolescent rugby athletes. Twenty-two rugby athletes were randomly allocated to groups that received instructions promoting an internal versus an external focus during a two week training programme. Landing forces were recorded before and after completion of the programme. During follow-up testing, landings were performed with and without a secondary cognitive task. Both groups exhibited a similar reduction in landing forces following training for trials performed without the secondary cognitive task. However, the groups responded differently when the secondary cognitive task was imposed. Athletes who were trained with an internal focus demonstrated a prominent increase in landing forces for trials that included the secondary cognitive task (vs. trials performed without the secondary cognitive task), whereas the secondary cognitive task had minimal influence for athletes who were trained with an external focus. It appears that training with an external focus may promote adaptations in landing mechanics that can be implemented more automatically.

Divided attention during cutting influences lower extremity mechanics in female athletes.

Anterior cruciate ligament (ACL) injuries in basketball appear to be more common when players are in possession of the ball. The greater risk of ACL injury when in possession of the ball may result from the athlete's inability to fully attend to their movement. However, it is also possible that having to carry/manipulate the ball restricts the athlete's ability to utilise their upper extremities for stability during a manoeuvre. The purpose of this study was to explore how possession of a basketball and divided attention influence lower extremity mechanics during cutting and landing. Twenty uninjured females with basketball experience performed a baseline lateral cutting task, as well as lateral cuts while carrying a basketball, with and without a subsequent chest pass. Requiring participants to carry the basketball in isolation (i.e., without the additional pass) had minimal influence on lower extremity mechanics compared to baseline. However, participants demonstrated less knee flexion (40.9° vs. 47.3°) and greater knee abduction (12.2° vs. 10.1°) for trials that included the additional pass (divided attention condition) compared to trials conducted while carrying the basketball in isolation. Athletes may be at greater risk for ACL injury when they are unable to solely attend to their movement.

Assessment of Knee Kinetic Symmetry Using Force Plate Technology.

CONTEXT: Athletes who have undergone an anterior cruciate ligament reconstruction often demonstrate more pronounced interlimb knee kinetic symmetry in comparison with uninjured athletes, even after they have completed rehabilitation. Part of the reason for the persistent asymmetry may be that sports medicine professionals are typically not able to assess knee joint kinetics within the clinic setting. Developing measures to assess knee joint kinetic symmetry could help to augment current rehabilitation practices. OBJECTIVE: The purpose of this study was to explore the extent to which interlimb vertical ground reaction force (GRF) symmetry can predict knee kinetic symmetry during a drop landing task. DESIGN: Cross-sectional study. SETTING: Motion analysis laboratory. PARTICIPANTS: A total of 21 uninjured subjects (9 males and 12 females). PROTOCOL: Three-dimensional kinematic data were collected using a multicamera system while subjects performed double-leg drop landings. GRF data were collected synchronously using 2 adjacent force plates. MAIN OUTCOME MEASURES: Knee joint moments and power were calculated for both limbs during the landing trials. An interlimb symmetry index (dominant/nondominant limb) was calculated for both the peak knee joint moment and power variables, as well as for the peak vertical GRFs. Linear regression analyses were performed to determine if the degree of symmetry in the peak vertical GRFs predicted the degree of symmetry for the kinetic variables. RESULTS: The symmetry index for the vertical GRFs was a significant predictor of the symmetry indices for the knee joint moments (r = .81; P < .001) and power (r = .88; P < .001). CONCLUSION: Interlimb symmetry in the peak vertical GRFs can be used to predict knee joint kinetic symmetry during a double-leg drop landing task.

Decision Making Influences Tibial Impact Accelerations During Lateral Cutting.

Lower-extremity musculoskeletal injuries are common in sports such as basketball and soccer. Athletes competing in sports of this nature must maneuver in response to the actions of their teammates, opponents, etc. This limits their ability to preplan movements. The purpose of this study was to compare impact accelerations during preplanned versus unplanned lateral cutting. A total of 30 subjects (15 males and 15 females) performed preplanned and unplanned cuts while the authors analyzed impact accelerations using an accelerometer secured to their tibia. For the preplanned condition, subjects were aware of the movement to perform before initiating a trial. For the unplanned condition, subjects initiated their movement and then reacted to the illumination of one of 3 visual stimuli which dictated whether they would cut, land, or land-and-jump. A mixed-model analysis of variance with a between factor of sex (male and female) and a within factor of condition (preplanned and unplanned) was used to analyze the magnitude and variability of the impact accelerations for the cutting trials. Both males and females demonstrated higher impact accelerations (P = .01) and a trend toward greater intertrial variability (P = .07) for the unplanned cutting trials (vs preplanned cuts). Unplanned cutting may place greater demands on the musculoskeletal system.

Cognitive Demands Influence Lower Extremity Mechanics During a Drop Vertical Jump Task in Female Athletes.

Study Design Cross-sectional study. Background The drop vertical jump task is commonly used to screen for anterior cruciate ligament injury risk; however, its predictive validity is limited. The limited predictive validity of the drop vertical jump task may be due to not imposing the cognitive demands that reflect sports participation. Objectives To investigate the influence of additional cognitive demands on lower extremity mechanics during execution of the drop vertical jump task. Methods Twenty uninjured women (age range, 18-25 years) were required to perform the standard drop vertical jump task, as well as drop vertical jumps that included additional cognitive demands. The additional cognitive demands were related to attending to an overhead goal (ball suspended overhead) and/or temporal constraints on movement selection (decision making). Three-dimensional ground reaction forces and lower extremity mechanics were compared between conditions. Results The inclusion of the overhead goal resulted in higher peak vertical ground reaction forces and lower peak knee flexion angles in comparison to the standard drop vertical jump task. In addition, participants demonstrated greater peak knee abduction angles when trials incorporated temporal constraints on decision making and/or required participants to attend to an overhead goal, in comparison to the standard drop vertical jump task. Conclusion Imposing additional cognitive demands during execution of the drop vertical jump task influenced lower extremity mechanics in a manner that suggested increased loading of the anterior cruciate ligament. Tasks utilized in anterior cruciate ligament injury risk screening may benefit from more closely reflecting the cognitive demands of the sports environment. J Orthop Sports Phys Ther 2018;48(5):381-387. Epub 10 Jan 2018. doi:10.2519/jospt.2018.7739.