The Running Readiness Scale as an Assessment of Kinematics Related to Knee Injury in Novice Female Runners.

CONTEXT: Frontal- and transverse-plane kinematics have been prospectively identified as risk factors for running-related injuries in females. The Running Readiness Scale (RRS) may allow for clinical evaluation of these kinematics. OBJECTIVES: To determine the reliability and validity of the RRS as an assessment of frontal- and transverse-plane running kinematics. DESIGN: Cross-sectional study. SETTING: University research laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 56 novice female runners (median [interquartile range] age = 34 years [26-47 years]). MAIN OUTCOME MEASURE(S): We collected 3-dimensional kinematics during running and RRS tasks: hopping, plank, step-ups, single-legged squats, and wall sit. Five clinicians assessed RRS performances 3 times each. Interrater and intrarater reliabilities of the total RRS score and individual tasks were calculated using the intraclass correlation coefficient and Fleiss κ, respectively. Pearson product moment correlation coefficients between peak joint angles measured during running and the same angles measured during RRS tasks were computed. Peak joint angles of high- and low-scoring participants were compared. RESULTS: Interrater and intrarater reliabilities of assessment of the total RRS scores were good (intraclass correlation coefficients = 0.75 and 0.80, respectively). Reliability of assessing individual tasks was moderate to almost perfect (κ = 0.58-1.00). Peak hip adduction, contralateral pelvic drop, and knee abduction during running were correlated with the same angles measured during hopping, step-ups, and single-legged squats (r = 0.537-0.939). Peak knee internal rotation during running was correlated with peak knee internal rotation during step-ups (r = 0.831). Runners who scored high on the RRS demonstrated less knee abduction during running (P ≤ .01). CONCLUSIONS: The RRS may effectively assess knee abduction in novice runners, but evaluation criteria or tasks may need to be modified to effectively characterize pelvic and transverse-plane knee kinematics.

Foot and Shank Coordination During Walking in Copers Compared With Patients With Chronic Ankle Instability and Controls.

Background: Chronic ankle instability (CAI) alters sensorimotor function and joint coordination, but ankle coordination during walking in copers (patients with a history of ankle sprain without any residual symptoms of CAI) remains unknown. Purpose: To identify foot and shank coordination patterns that discriminate among individuals with CAI, copers, and healthy controls and to investigate whether copers display a different strategy to overcome altered sensorimotor function after a lateral ankle sprain compared with individuals with CAI and healthy controls. Study Design: Controlled laboratory study. Methods: A total of 51 participants (17 participants with CAI, 17 copers, 17 healthy controls) walked on an instrumented treadmill at a fixed speed of 1.20 m/s for a 10-second trial, from which 8 consecutive gait cycles were extracted for analysis. Heel strike and toe-off were identified for each stance phase, and each stance phase was normalized to 100 time frames. A curve analysis was performed to detect group mean differences in vector coding coupling angles and coordination variabilities for sagittal plane ankle motion/transverse plane tibial plane motion (SAK/TT) and frontal plane ankle motion/transverse plane tibial motion (FAK/TT) with 90% CIs. Results: During the terminal stance, CAI and coper groups demonstrated an inversion-tibial external rotation coupling, while controls displayed a dorsiflexion-tibial internal rotation strategy. During midstance, there were no differences between the coper, CAI, or control groups. At 0% to 20% of stance, the CAI group showed the most variability, while copers showed the least. During midstance, both copers and controls displayed an increase in variability earlier than the CAI group. The CAI group displayed a peak in variability from 39% to 43% of stance, which was greater than copers. During the propulsive phase (from heel-off to toe-off), the CAI group showed greater SAK/TT variability than both copers and controls. Similar to SAK/TT variability, the CAI group showed an earlier peak in FAK/TT variability compared with controls. Conclusion: The CAI, coper, and control groups displayed different ankle joint coupling patterns and coordination variability during a walking gait cycle. Clinical Relevance: Copers may have the ability to alter their coordination during walking, which may help us understand the underlying mechanism of CAI.

Comparison of Frontal and Transverse Plane Kinematics Related to Knee Injury in Novice Versus Experienced Female Runners.

Novice runners experience a higher incidence of knee injury than experienced runners, which may be related to aberrant frontal and transverse plane kinematics. However, differences in kinematics between novice and experienced runners have not been fully explored. For this study, 10 novice and 10 experienced female runners ran on a treadmill at 2.68 m/s. Ankle, knee, and hip joint angles during the stance phase were measured using a 3-dimensional motion capture system and modeled using cubic splines. Spline models were compared between groups using a generalized linear model (α = .05). Ninety-five percent confidence intervals of the difference between joint angles throughout stance were constructed to identify specific periods of stance where groups differed in joint position. Angle-angle diagrams of ankle and hip position in the frontal and transverse planes were constructed to depict joint coordination. Novice runners displayed less hip adduction, but greater knee abduction and knee internal rotation compared to experienced runners. Differences in knee joint position may be explained by coordination of hip and ankle motion. Greater knee abduction and knee internal rotation displayed by novice runners compared with experienced runners may help to explain their higher risk for injury.

A case of ANCA-associated vasculitis presenting de novo in pregnancy, successfully treated with rituximab.

Antineutrophil cytoplasm antibody (ANCA)-associated vasculitides are rare small vessel vasculitides of unknown cause. The pathogenic role of MPO-ANCA in the vasculitides has been supported using various animal models, with B-cells playing a role in the disease pathogenesis. Pregnancy in the presence of an autoimmune disease such as vasculitis is often associated with significant morbidity. Little is known about the outcomes when women present with de novo vasculitis during pregnancy, and the appropriate management of such presentations is unclear. We describe a case of a 33-year-old female presenting in her second pregnancy with new onset ANCA vasculitis at 12 weeks' gestation. She was successfully treated with prednisolone and rituximab, and delivered a healthy 2.8 kg boy at 36 weeks' gestation with no clinical manifestations of vasculitis or neutropenia in the neonate.

Ankle Coordination in Chronic Ankle Instability, Coper, and Control Groups in Running.

PURPOSE: Coordination and coordination variability have been used as a measure of the function and flexibility of the sensorimotor system during running. Chronic ankle instability (CAI) is associated with altered sensorimotor system function compared with individuals without CAI. Copers may have adopted protective sensorimotor adaptations to prevent repeated ankle sprains; however, their coordination strategies between the foot and shank have not been investigated. We compared joint coupling angles and coordination variability using vector coding between individuals with CAI, copers, and controls. METHODS: Seventeen individuals with CAI, 17 copers, and 17 controls ran on the treadmill at a fixed speed of 2.68 m·s. A 10-s trial of continuous data was collected for kinematic analysis. The first five complete strides were used for vector coding. Means of the vector coding angles and variability of frontal plane ankle motion/transverse plane tibia motion and sagittal plane ankle motion/transverse plane tibia motion (SAK/TT) were calculated. A curve analysis with 90% confidence intervals was performed to detect differences between groups. RESULTS: Controls demonstrated greater angles of SAK/TT than individuals with CAI and greater angles of FAK/TT than copers during the second half of stance. In general, the control group demonstrated greater variability than individuals with CAI and copers, and copers demonstrated greater variability than individuals with CAI. CONCLUSIONS: Chronic ankle instability and copers demonstrated different coordination strategies than controls during loading and propulsion, adding evidence to support a sensorimotor deficit or compensation. Further, limited variability in people with history of CAI during impact and midstance may contribute to higher risk of reinjury, and be an important area for further research.

Statistical Parametric Mapping as a Measure of Differences Between Limbs: Applications to Clinical Populations.

In healthy individuals, symmetrical lower-extremity movement is often assumed and calculated using discrete points during various tasks. However, measuring overall movement patterns using methods such as statistical parametric mapping (SPM) may allow for better interpretation of human movement. This study demonstrated the ability of SPM to assess interlimb differences in lower-extremity movement during 2 example tasks: running and landing. Three-dimensional motion analysis was used to determine sagittal and frontal plane lower-extremity joint angles in (1) young and older individuals during running and (2) patients with anterior cruciate ligament reconstruction and uninjured control athletes during landing. Interlimb differences within each group were compared using SPM and paired t tests on peak discrete angles. No differences between limbs were found between young and older runners using SPM. Peak ankle eversion and plantar flexion angles differed between limbs in young and older runners. Sagittal plane hip angle varied between limbs in uninjured control athletes. Frontal plane ankle angle and sagittal plane knee and hip angles differed between limbs in patients with anterior cruciate ligament reconstruction using SPM and discrete analysis. These data suggest that SPM can be useful to determine clinically meaningful interlimb differences during running and landing in multiple populations.

Ligamentous Lisfranc Injury: A Biomechanical Comparison of Dorsal Plate Fixation and Transarticular Screws.

OBJECTIVES: Optimal fixation technique after purely ligamentous Lisfranc injury remains controversial. This biomechanical study compares dorsal plate versus transarticular screw fixation by measuring dorsal and plantar joint diastasis. A unique protocol was developed, using reflective triad markers and positional cameras. METHODS: Eleven cadaveric matched pairs were assigned to either transarticular screw or dorsal plate fixation. Two reflective triad markers were placed into the medial cuneiform (C1) and second metatarsal base (MT2). Three cameras recorded the 3-dimensional location of triads to quantify C1-MT2 diastasis in the following states: intact Lisfranc ligament (INTACT), cut ligament (CUT), fixed (SCREW or PLATE) joint, and fixed joint after 10,000 loaded cycles. On completion, the plantar Lisfranc ligament insertions were identified, and plantar diastasis was determined using additional reflective triads. Statistical post hoc pairwise comparisons assessed differences in diastasis. RESULTS: C1-MT2 diastasis in the CUT state increased relative to INTACT (P < 0.001). SCREW fixation reduced C1-MT2 diastasis relative to CUT at dorsal (P < 0.007) and plantar (P = 0.015) locations after cycling. PLATE fixation significantly reduced dorsal diastasis relative to CUT (P < 0.001) but not for plantar diastasis (P > 0.99). PLATE plantar diastasis was numerically higher than INTACT but not significantly (P > 0.39). PLATE plantar diastasis tended to be greater than SCREW before cycling (P = 0.068) and after cycling (P = 0.080). CONCLUSIONS: Transection of the Lisfranc ligament complex yielded C1-MT2 diastasis. Both SCREW and PLATE fixation successfully reduced dorsal diastasis. However, upon load, the PLATE resulted in greater plantar diastasis, nearly statistically different relative to the SCREW. Cyclic loading at 343 N did not worsen diastasis.

Inter-joint coordination patterns differ between younger and older runners.

Older runners are at greater risk of certain running-related injuries. Previous work demonstrated that aging influences running biomechanics, and suggest a compensatory relation between changes in the proximal and distal joints. Previous comparisons of interjoint coordination strategies between young and older runners could potentially have missed relevant differences by averaging coordination measures across time. OBJECTIVE: To compare coordination strategies between male runners under the age of 30 to those over the age of 60. METHODS: Twelve young (22 ±â€¯3 yrs, 1.80 ±â€¯0.07 m, 78.0 ±â€¯12.1 kg) and 12 older (63 ±â€¯3 yrs, 1.78 ±â€¯0.06 m, 73.2 ±â€¯15.8 kg) male runners ran at 3.35 m/s on an instrumented treadmill. Ankle frontal plane, tibial transverse plane, knee sagittal plane, and hip frontal plane motion were measured. Inter-joint coordination was calculated using a modified vector coding technique. Coordination patterns and variability time series were compared between groups throughout stance using ANOVA for circular data. RESULTS: At the ankle, older runners use in-phase propulsion (inversion, tibia external rotation) pattern following midstance (46-47% stance) while young runners are still in an in-phase collapse pattern (eversion, tibia external rotation). In coordination of the knee and hip, older runners maintained an in-phase collapse pattern (knee flexion, hip adduction) approaching midstance (35-37% stance), while younger runners use an out of phase strategy (knee extension, hip adduction). In coordination of the ankle and hip in the frontal plane, older runners again maintained an in phase collapse pattern up to midstance (34-39% stance), while younger runners used an out of phase strategy (ankle inversion, hip adduction). Variability was similar between age groups. CONCLUSION: Older runners appear to display altered coordination patterns during mid-stance, which may indicate protective biomechanical adaptations. These changes may also have implications for performance in older runners.

Tibiofemoral Joint Forces in Female Recreational Runners Vary with Step Frequency.

PURPOSE: Elevated tibiofemoral joint (TFJ) contact forces have been linked to the development and progression of knee osteoarthritis. The primary objective of this study was to determine the association between peak TFJ shear and compression forces during running at different self-selected step frequencies (SF) in female recreational runners. METHODS: Fifty-five healthy female recreational runners ran at 2.98 m·s on an instrumented treadmill. Peak TFJ anterior shear force, peak axial TFJ compression force, and peak medial compartment TFJ compression force were estimated using a musculoskeletal model with inputs from 3D joint kinematics and inverse dynamics calculations. Three SF groups were generated using tertiles, and differences between the groups were compared using one-way ANOVA (α = 0.05). RESULTS: Runners with an SF of ≥178 steps per minute demonstrated the lowest peak TFJ anterior shear force (P = 0.04), peak axial TFJ compression force (P = 0.01), and peak TFJ medial compartment compression forces (P = 0.01) compared with runners using lower SF. CONCLUSION: Female recreational runners with low SF of ≤166 steps per minute experience greater TFJ contact forces. This study provides evidence of an association between SF and both shear and axial peak TFJ contact forces during running.

The Reliability and Validity of the Loadsol® under Various Walking and Running Conditions.

The assessment of loading during walking and running has historically been limited to data collection in laboratory settings or with devices that require a computer connection. This study aims to determine if the loadsol®-a single sensor wireless insole-is a valid and reliable method of assessing force. Thirty (17 male and 13 female) recreationally active individuals were recruited for a two visit study where they walked (1.3 m/s) and ran (3.0 and 3.5 m/s) at a 0%, 10% incline, and 10% decline, with the visits approximately one week apart. Ground reaction force data was collected on an instrumented treadmill (1440 Hz) and with the loadsol® (100 Hz). Ten individuals completed the day 1 protocol with a newer 200 Hz loadsol®. Intraclass correlation coefficients (ICC3,k) were used to assess validity and reliability and Bland⁻Altman plots were generated to better understand loadsol® validity. Across conditions, the peak force ICCs ranged from 0.78 to 0.97, which increased to 0.84⁻0.99 with the 200 Hz insoles. Similarly, the loading rate ICCs improved from 0.61 to 0.97 to 0.80⁻0.96 and impulse improved from 0.61 to 0.97 to 0.90⁻0.97. The 200 Hz insoles may be needed for loading rate and impulse in running. For both walking and running, the loadsol® has excellent between-day reliability (>0.76).

Clinical Predictors of Dynamic Lower Extremity Stiffness During Running.

BACKGROUND: Lower extremity stiffness describes the relative loading and kinematics of the entire lower extremity during ground contact. Previously injured subjects demonstrate altered lower extremity stiffness values. Clinical analysis of lower extremity stiffness is not currently feasible due to increased time and cost. OBJECTIVE: To determine the clinically identifiable contributors to lower extremity stiffness. METHODS: In this cross-sectional controlled laboratory study, 92 healthy runners completed a clinical screening involving passive assessment of hip, knee, and ankle range of motion, along with body anthropometrics. The range of motion was predominantly assessed in the sagittal and frontal planes. In the same session, runners completed an overground kinematic and kinetic running assessment at 3.35 m/s (±5%) to obtain lower extremity stiffness. Correlations between lower extremity stiffness and clinical variables were completed. Modifiable variables were included in an all-possible-linear regressions approach to determine a parsimonious model for predicting lower extremity stiffness. RESULTS: Clinically modifiable measures included in the regression model accounted for 48.4% of the variance of lower extremity stiffness during running. The variables that predicted greater stiffness included greater body mass, less ankle dorsiflexion range of motion with the knee flexed, less hip internal rotation range of motion, and less first-ray mobility. CONCLUSION: Reduced lower extremity range of motion and greater body mass are associated with greater lower extremity stiffness during running. These variables could be addressed clinically to potentially alter lower extremity stiffness and injury risk. J Orthop Sports Phys Ther 2019;49(2):98-104. Epub 27 Jul 2018. doi:10.2519/jospt.2019.7683.

Influence of Aging on Lower Extremity Sagittal Plane Variability During 5 Essential Subphases of Stance in Male Recreational Runners.

BACKGROUND: Interjoint coordination variability is a measure of the ability of the human system to regulate multiple movement strategies. Normal aging may reduce variability, resulting in a less adaptive system. Additionally, when older runners are asked to run at speeds greater than preferred, this added constraint may place older runners at greater risk for injury. OBJECTIVES: To examine the influence of normal aging on coordination variability across 5 distinct subphases of stance in runners during preferred and fixed speeds. METHODS: Twelve older (60 years of age or older) and 12 younger (30 years of age or younger) male recreational runners volunteered for this cross-sectional study. Three-dimensional gait analyses were collected at preferred and fixed speeds. Stance phase was divided into 5 subphases: (SP1) loading response, (SP2) peak braking, (SP3) peak compression, (SP4) midstance, and (SP5) peak propulsion. Continuous relative phase variability for sagittal plane joint pairs-hip-knee, knee-ankle, and hip-ankle-was calculated. Repeated-measures linear mixed models were employed to compare variability for each joint pair. RESULTS: An age-by-stance subphase interaction was found for knee-ankle (P<.01) and hip-ankle (P<.01) pairs, while main effects for age and stance subphase were found for the hip-knee pair (P<.05). Specifically, loading response and peak braking variability were lower in older runners and greater across stance for knee-ankle and hip-ankle pairs, while midstance was lowest in the hip-knee pair for older and younger runners. No effects for running pace were found. CONCLUSION: Less adaptive movement strategies seen in older runners may partially contribute to the increased eccentric stresses during periods of high load. J Orthop Sports Phys Ther 2019;49(3):171-179. Epub 30 Nov 2018. doi:10.2519/jospt.2019.8419.

Kinematic predictors of loading during running differ by demographic group.

OBJECTIVES: To investigate whether previously-determined kinematic predictors of kinetics during running differ between demographic groups. PARTICIPANTS: Young male (n = 13, age = 22 (2) yrs), young female (n = 13, age = 25 (4) yrs), older male (n = 13, age = 50 (4) yrs) and older female (n = 13, age = 52 (3) yrs) runners. MAIN OUTCOME MEASURES: Sagittal plane kinematics and kinetics were assessed while participants ran at their preferred pace. Linear regression models were developed to predict kinetics in each group using kinematics as independent variables. RESULTS: Step length was positively associated with magnitude of at least one kinetic variable in all groups. Step position was inversely associated with vertical ground reaction force variables in all groups. Step frequency and CoM excursion were also important to all groups, however direction of the associations varied. Foot angle at initial contact was important to all groups except older females. Peak knee flexion was most important to older females, but was not important to any other groups. CONCLUSION: Optimal parameters for gait analysis of runners may depend on demographics of the individual. This provides insight for clinicians into the most effective evaluation and interventions strategies for different types of runners.

Influence of rest interval on foot-tibia coordination with chronic ankle instability during the Star Excursion Balance Test.

The purpose of this study was to determine whether different rest intervals affect performance on the Star Excursion Balance Test (SEBT) associated with chronic ankle instability (CAI) and whether foot-tibia coordination can be associated factors that may help discriminate between individuals with and without CAI during the SEBT. Participants included forty-eight individuals with (n = 24) and without CAI (n = 24). Subjects completed 3 trials in each of the 3 reach directions (anteromedial, medial, posteromedial) in random order. A total of three visits were required to complete the 3 rest interval conditions (10, 20, 40 s). Coupling angles (CA) of tibial internal rotation/dorsiflexion (TIR/DF) and tibial internal rotation/eversion (TIR/EV) were calculated and compared between groups in each direction for each rest interval. Individuals with CAI showed greater CAs of TIR/DF in the M direction (p = 0.01) and of TIR/EV in the P direction (p = 0.04) than healthy individuals in 20 s rest interval time. Overall, joint CAs were different between healthy individuals and those with CAI during the SEBT regardless of rest interval. Based on these results, rest interval and a natural result of CAI could alter ankle joint coordination in comparison of healthy individuals when performing the SEBT.

Changes in Vertical and Joint Stiffness in Runners With Advancing Age.

Powell, DW and Williams, DSB. Changes in vertical and joint stiffness in runners with advancing age. J Strength Cond Res 32(12): 3425-3431, 2018-Age-related changes in the neuromuscular system underlie reduced performance and injury but may be mitigated through regular physical activity. It was hypothesized that older (OLD) compared with young (YOUNG) adults would exhibit greater vertical and joint stiffness when running at 3.35 m·s. Nine YOUNG and 10 OLD runners performed over ground running trials while three-dimensional biomechanics were recorded. Ankle and knee joint angles, moments and stiffness values were compared between YOUNG & OLD. YOUNG had smaller vertical stiffness (p = 0.01; YOUNG: 32.8 ± 3.6; OLD: 38.1 ± 5.7) and greater joint stiffness than OLD at the ankle (p = 0.04; YOUNG: 0.134 ± 0.021; OLD: 0.118 ± 0.017) and knee (p = 0.01; YOUNG: 0.119 ± 0.016; OLD: 0.098 ± 0.014). YOUNG exhibited greater peak knee flexion angles (p = 0.04; YOUNG: 43.4 ± 6.5°; OLD: 39.1 ± 2.6°), and peak ankle plantarflexion (p = 0.02; YOUNG: -2.8 ± 0.4 Nm·kg; OLD: -2.5 ± 0.1 Nm·kg) and knee extension moments (p < 0.01; 2.6 ± 0.3 Nm·kg; OLD: 2.1 ± 0.2 Nm·kg) than OLD whereas no differences were observed in peak ankle dorsiflexion angles (p = 0.44; YOUNG: 23.6 ± 4.2°; OLD: 23.4 ± 2.1°). The findings of this study suggest that OLD compared with YOUNG adults adopt altered lower extremity biomechanics. These altered running biomechanics by seek to minimize the metabolic cost of running or may be a function of reduced lower extremity strength and power.

Biomechanical Implications of Training Volume and Intensity in Aging Runners.

Running speed is slower in middle-age compared with younger runners due to reduced ankle but not hip and knee kinetic output. Running-specific training helps attenuate age-related declines in measures of endurance, muscle strength, and gait speed. Considering the adaptability of the human body in response to imposed stresses, maintaining training volume and intensity may play a role in modifying running biomechanics in middle-age runners. PURPOSE: To compare running biomechanics between young and middle-age runners when controlling for the confounding effects of training volume and intensity. METHODS: Fifteen middle-age runners, 15 young runners with similar training volume as the middle-age group and, 15 young runners with similar preferred training paces (i.e., intensity) as the middle-age runners participated in the study. Lower-limb joint kinetics were calculated from kinematic and ground reaction force data during overground running at a submaximal speed and compared among groups. RESULTS: Middle-age runners ran with similar peak ankle power compared with volume-matched younger runners although peak plantarflexor moment was 10.5% lower in the middle age group (P = 0.046; Cohen d = 0.78). Middle-age runners ran with similar ankle plantarflexor moment and joint power compared with training pace-matched young runners. As expected, no age-related differences were observed in hip and knee kinetics when training volume or pace were matched between age groups. These results suggest that training pace may be more effective in attenuating age-related declines in plantarflexor kinetics in middle-age runners. CONCLUSIONS: From these findings, we propose the hypothesis that both training volume and training pace may play a role in maintaining plantarflexor kinetics but that training pace may have a greater impact on ankle plantarflexor kinetics in middle-age runners.

Contributions to Leg Stiffness in High- Compared with Low-Arched Athletes.

PURPOSE: High-arched (HA) athletes exhibit greater lower extremity stiffness during functional tasks than low-arched (LA) athletes. The contributions of skeletal and muscular structures to stiffness may underlie the distinct injury patterns observed in these athletes. The purpose of this study was to compare skeletal and muscular contributions to leg stiffness in HA and LA athletes during running and landing tasks. METHODS: Ten HA and 10 LA female athletes performed five overground running trials at a self-selected pace and five step off bilateral landing trials from a height of 30 cm. Three-dimensional kinematics and kinetics were collected using a motion capture system and a force platform. Leg stiffness and its skeletal and muscular contributions were calculated. Independent t-tests were used to compare variable means between arch type groups and Cohen's d were computed to assess effect sizes of mean differences. RESULTS: In running, HA athletes had greater leg stiffness (P = 0.010, d = 1.03) and skeletal stiffness (P = 0.016, d = 0.81), although there are no differences in muscular stiffness (P = 0.134). During landing, HA had greater leg stiffness (P = 0.015, d = 1.06) and skeletal stiffness (P < 0.001, d = 1.84), whereas LA athletes had greater muscular stiffness (P = 0.025, d = 0.96). CONCLUSIONS: These findings demonstrate that HA athletes place a greater reliance on skeletal structures for load attenuation during running and landing, whereas LA athletes rely more greatly on muscle contributions during landing only. These findings may provide insight into the distinct injury patterns observed in HA and LA athletes.

The effect of variable rest intervals and chronic ankle instability on triplanar ankle motion during performance of the Star Excursion Balance Test.

Inadequate rest intervals may contribute to impaired performance during functional tests. However, the effect of different rest intervals on performance of the SEBT in individuals with and without CAI is not known. Our purposes were to determine whether different rest intervals impact ankle kinematics during the SEBT and whether there differences between those two populations. 24 controls and 24 CAI completed 3 trials in 3 reach directions (anteromedial; AM, medial; M, posteromedial; PM). The order of rest intervals and reach distance were randomized and counterbalanced. Three visits were required to complete the 3 rest interval conditions (10, 20, 40s). Rest interval did not impact ankle kinematics between controls and CAI during the SEBT. Dorsiflexion (DF) (AM:partial η2=0.18; M:partial η2=0.23; PM:partial η2=0.23) for all directions and tibial internal rotation (TIR) excursions (AM:partial η2=0.20) for AM direction were greater in individuals with CAI regardless of rest interval length. Rest intervals ranging from 10 to 40s did not influence ankle kinematics. Differences exist in DF and TIR between controls and CAI during the SEBT. These findings suggest that clinicians can use any rest interval between 10 and 40s when administrating the SEBT. However, triplanar motion differs during a complex functional movement in controls compared to CAI.

Sex differences in total frontal plane knee movement and velocity during a functional single-leg landing.

OBJECTIVES: Females land with more knee valgus than males. While most studies have evaluated lower extremity mechanics during double leg landing, most sports require single-leg landing from a double or single leg takeoff. Further, knee movement occurs toward both varus and valgus during functional landing. The purpose of this study was to determine if differences exist between females and males in total frontal plane movement and velocity of the knee during single-leg landing. DESIGN: Experimental cohort. SETTING: Motion analysis laboratory. PARTICIPANTS: Forty healthy, physically-active females (n = 20) and males (n = 20). MAIN OUTCOME MEASURES: Three-dimensional motion analysis was completed on the lower extremities during double-leg jumping followed by a single-leg landing. Student's t-tests (p ≤ 0.05) were used to determine if differences exist in frontal plane knee angles (valgus and varus excursion) and angular velocities between females and males. RESULTS: Females demonstrated greater knee valgus and varus excursion, and valgus and varus velocities compared to males (p < 0.05). CONCLUSIONS: These findings suggest that total movement in the frontal plane at the knee may be an important factor in injury mechanics in females. Further, single-leg landing from a functional jump should be considered when comparing landing biomechanics between females and males.