Lower extremity kinematics during running and hip abductor strength in iliotibial band syndrome: A systematic review and meta-analysis.

BACKGROUND: Iliotibial band syndrome is a common overuse injury that is twice as likely to affect female runners compared to male runners. It is unclear if there is a consistent running pattern and strength profile exhibited by female and male runners with iliotibial band syndrome. RESEARCH QUESTION: The purpose of this systematic review and meta-analysis was to determine if any differences existed in lower-extremity kinematics and hip strength between runners who retrospectively, currently, or prospectively had iliotibial band syndrome. METHODS: Papers included must have reported three-dimensional kinematic running data and/or hip strength data that were statistically analyzed between runners that never developed iliotibial band syndrome and runners with iliotibial band syndrome. Meta-analysis was performed for each kinematic or strength variable reported in at least three studies. Female and male runners were analyzed separately and grouped into three cohorts (retrospective, current, prospective). RESULTS: Seventeen articles were included in this systematic review. Data from 10 cross-sectional studies were included for meta-analysis. Female runners with current iliotibial band syndrome exhibited smaller peak hip internal rotation angles and lower isometric hip abductor strength compared to controls. SIGNIFICANCE: Although limited biomechanical evidence exists, risk factors for ITBS are different between female and male runners and may vary according to injury status. Specifically, transverse plane hip motion and hip abductor strength weakness may be biomechanical risk factors in female runners with current iliotibial band syndrome only.

Biomechanics associated with tibial stress fracture in runners: A systematic review and meta-analysis.

BACKGROUND: Tibial stress fracture (TSF) is an overuse running injury with a long recovery period. While many running studies refer to biomechanical risk factors for TSF, only a few have compared biomechanics in runners with TSF to controls. The aim of this systematic review and meta-analysis was to evaluate biomechanics in runners with TSF compared to controls. METHODS: Electronic databases PubMed, Web of Science, SPORTDiscus, Scopus, Cochrane, and CINAHL were searched. Risk of bias was assessed and meta-analysis conducted for variables reported in 3 or more studies. RESULTS: The search retrieved 359 unique records, but only the 14 that compared runners with TSF to controls were included in the review. Most studies were retrospective, 2 were prospective, and most had a small sample size (5-30 per group). Many variables were not significantly different between groups. Meta-analysis of peak impact, active, and braking ground reaction forces found no significant differences between groups. Individual studies found larger tibial peak anterior tensile stress, peak posterior compressive stress, peak axial acceleration, peak rearfoot eversion, and hip adduction in the TSF group. CONCLUSION: Meta-analysis indicated that discrete ground reaction force variables were not statistically significantly different in runners with TSF compared to controls. In individual included studies, many biomechanical variables were not statistically significantly different between groups. However, many were reported by only a single study, and sample sizes were small. We encourage additional studies with larger sample sizes of runners with TSF and controls and adequate statistical power to confirm or refute these findings.

Weak associations between hip adduction angle and hip abductor muscle activity during running.

Hip abductor muscle strengthening is often prescribed to reduce the peak hip adduction angle in runners with overuse knee injury. However, no evidence exists associating greater isometric hip abductor muscle strength with smaller peak hip adduction angle during running. Beyond muscle strength, muscle activation patterns may play an important role in controlling joint movement during running. Therefore, the purpose of this investigation was to determine if associations existed among hip adduction angle, hip abductor muscle activity, and isometric hip abductor muscle strength. Twenty-five currently healthy female runners participated. Average gluteus medius muscle activity and tensor fascia lata muscle activity were determined during hip abductor maximal voluntary isometric contractions. Three-dimensional kinematics and hip abductor muscle activity were collected during treadmill running. Dependent variables were analyzed via Pearson product moment correlations. Multi-variable linear regression determined muscle activity's and strength's contributions to the peak hip adduction angle. A fair positive correlation was observed between the peak hip adduction angle and average tensor fascia lata muscle activity magnitude. Additionally, there was a moderate negative correlation between isometric hip abductor muscle strength and average gluteus medius muscle activity magnitude. Tensor fascia lata activity magnitude accounted for the most variance of the peak hip adduction angle. This study adds to the literature which indicates a lack of association between isometric hip abductor muscle strength and peak hip adduction angle in healthy runners. Factors other than hip abductor muscle strength and activation may account for more of the variance in peak hip adduction angles among runners.

Relationship between iliotibial band syndrome and hip neuromechanics in women runners.

BACKGROUND: Atypical frontal plane hip kinematics are associated with iliotibial band syndrome in women runners. Gluteus medius is the primary muscle controlling the hip adduction angle during the loading response of stance. It is unclear if differences exist in gluteus medius activity magnitude and activity duration between runners with previous iliotibial band syndrome and controls. Furthermore, hip neuromechanics may change after a prolonged run. RESEARCH QUESTION: Do differences exist in the hip adduction angle and gluteus medius activity between women with previous iliotibial band syndrome and controls at the beginning and end of a 30-minute moderate paced treadmill run? METHODS: Thirty women participated (n = 15 controls). Lower extremity kinematics and gluteus medius activity were recorded at the start and end of a 30-minute treadmill run at participants' self-selected pace. Hip kinematics and gluteus medius activity were analyzed via separate two-way (group x time) mixed-model analysis of variance with time as the repeated measure. RESULTS: Hip neuromechanics were similar at the start and end of a 30-minute treadmill run in women with previous iliotibial band syndrome and controls. However, hip adduction excursion was less in women with previous iliotibial band syndrome compared to controls. Average gluteus medius activity magnitude and activity duration were not significantly different between groups. SIGNIFICANCE: These findings support the growing body of literature that smaller hip adduction motion is related to previous iliotibial band syndrome in women. Regardless of injury history, gluteus medius activity was similar between groups during the loading phase of stance.

Influence of Previous Iliotibial Band Syndrome on Coordination Patterns and Coordination Variability in Female Runners.

It is unknown if female runners that have sustained multiple iliotibial band syndrome occurrences run differently compared to runners that developed the injury once or controls. Therefore, the purpose of this study was to determine if differences existed in coordination patterns and coordination variability among female runners with recurrent iliotibial band syndrome, one iliotibial band syndrome occurrence, and controls. Overground running trials were collected for 36 female runners (n = 18 controls). Lower extremity coordination patterns were examined during running via a vector coding analysis. Coordination variability was calculated via the ellipse area method. Separate one-way (group) Kruskal-Wallis tests were performed to compare each coordination pattern and coordination variability. Lower extremity coordination between frontal plane hip - transverse plane hip, frontal plane pelvis - frontal plane thigh, and frontal plane thigh - transverse plane shank was similar among groups and so may not be related to the risk of iliotibial band syndrome. Runners with one iliotibial band syndrome occurrence demonstrated greater coordination variability for two of three couplings compared to both controls and runners with recurrent iliotibial band syndrome. Thus, the number of previous injury episodes may influence coordination variability in female runners with a history of iliotibial band syndrome.

NOT ALL SINGLE LEG SQUATS ARE EQUAL: A BIOMECHANICAL COMPARISON OF THREE VARIATIONS.

BACKGROUND: The single leg squat (SLS) is a functional task used by practitioners to evaluate and treat multiple pathologies of the lower extremity. Variations of the SLS may have different neuromuscular and biomechanical demands. The effect of altering the non-stance leg position during the SLS on trunk, pelvic, and lower extremity mechanics has not been reported. PURPOSE: The purpose of this study was to compare trunk, pelvic, hip, knee, and ankle kinematics and hip, knee, and ankle kinetics of three variations of the SLS using different non-stance leg positions: SLS-Front, SLS-Middle, and SLS-Back. METHODS: Sixteen healthy women performed the three SLS tasks while data were collected using a motion capture system and force plates. Joint mechanics in the sagittal, frontal, and transverse planes were compared for the SLS tasks using a separate repeated-measures analysis of variance (ANOVA) for each variable at two analysis points: peak knee flexion (PKF) and 60 ° of knee flexion (60KF). RESULTS: Different non-stance leg positions during the SLS resulted in distinct movement patterns and moments at the trunk, pelvis, and lower extremity. At PKF, SLS-Back exhibited the greatest kinematic differences (p < 0.05) from SLS-Front and SLS-Middle with greater ipsilateral trunk flexion, pelvic anterior tilt and drop, hip flexion and adduction, and external rotation as well as less knee flexion and abduction. SLS-Back also showed the greatest kinetic differences (p < 0.05) from SLS-Front and SLS-Middle with greater hip external rotator moment and knee extensor moment as well as less hip extensor moment and knee adductor moment at PKF. At 60KF, the findings were similar except at the knee. CONCLUSION: The mechanics of the trunk, pelvis, and lower extremity during the SLS were affected by the position of the non-stance leg in healthy females. Practitioners can use these findings to distinguish between SLS variations and to select the appropriate SLS for assessment and rehabilitation. LEVEL OF EVIDENCE: 3.

Differences in Lower Extremity and Trunk Kinematics between Single Leg Squat and Step Down Tasks.

The single leg squat and single leg step down are two commonly used functional tasks to assess movement patterns. It is unknown how kinematics compare between these tasks. The purpose of this study was to identify kinematic differences in the lower extremity, pelvis and trunk between the single leg squat and the step down. Fourteen healthy individuals participated in this research and performed the functional tasks while kinematic data were collected for the trunk, pelvis, and lower extremities using a motion capture system. For the single leg squat task, the participant was instructed to squat as low as possible. For the step down task, the participant was instructed to stand on top of a box, slowly lower him/herself until the non-stance heel touched the ground, and return to standing. This was done from two different heights (16 cm and 24 cm). The kinematics were evaluated at peak knee flexion as well as at 60° of knee flexion. Pearson correlation coefficients (r) between the angles at those two time points were also calculated to better understand the relationship between each task. The tasks resulted in kinematics differences at the knee, hip, pelvis, and trunk at both time points. The single leg squat was performed with less hip adduction (p ≤ 0.003), but more hip external rotation and knee abduction (p ≤ 0.030), than the step down tasks at 60° of knee flexion. These differences were maintained at peak knee flexion except hip external rotation was only significant in the 24 cm step down task (p ≤ 0.029). While there were multiple differences between the two step heights at peak knee flexion, the only difference at 60° of knee flexion was in trunk flexion (p < 0.001). Angles at the knee and hip had a moderate to excellent correlation (r = 0.51-0.98), but less consistently so at the pelvis and trunk (r = 0.21-0.96). The differences in movement patterns between the single leg squat and the step down should be considered when selecting a single leg task for evaluation or treatment. The high correlation of knee and hip angles between the three tasks indicates that similar information about knee and hip kinematics was gained from each of these tasks, while pelvis and trunk angles were less well predicted.

Associations between iliotibial band injury status and running biomechanics in women.

Iliotibial band syndrome (ITBS) is a common overuse knee injury that is twice as likely to afflict women compared to men. Lower extremity and trunk biomechanics during running, as well as hip abductor strength and iliotibial band flexibility, are factors believed to be associated with ITBS. The purpose of this cross-sectional study was to determine if differences in lower extremity and trunk biomechanics during running exist among runners with current ITBS, previous ITBS, and controls. Additionally, we sought to determine if isometric hip abductor strength and iliotibial band flexibility were different among groups. Twenty-seven female runners participated in the study. Participants were divided into three equal groups: current ITBS, previous ITBS, and controls. Overground running trials, isometric hip abductor strength, and iliotibial band flexibility were recorded for all participants. Discrete joint and segment biomechanics, as well as hip strength and flexibility measures were analyzed using a one-way analysis of variance. Runners with current ITBS exhibited 1.8 (1.5)° greater trunk ipsilateral flexion and 7 (6)° less iliotibial band flexibility compared to runners with previous ITBS and controls. Runners with previous ITBS exhibited 2.2 (2.9) ° less hip adduction compared to runners with current ITBS and controls. Hip abductor strength 3.3 (2.6) %BM×h was less in runners with previous ITBS but not current ITBS compared to controls. Runners with current ITBS may lean their trunk more towards the stance limb which may be associated with decreased iliotibial band flexibility.

Frontal plane running biomechanics in female runners with previous iliotibial band syndrome.

Proximal factors such as excessive frontal plane pelvis and trunk motion have been postulated to be biomechanical risk factors associated with iliotibial band syndrome. In addition, lateral core endurance deficiencies may be related to increased pelvis and trunk motion during running. The purpose of this cross-sectional investigation was to determine if differences in biomechanics during running, as well as lateral core endurance exist between female runners with previous iliotibial band syndrome and controls. Gait and lateral core endurance were assessed in 34 female runners (17 with previous iliotibial band syndrome). Multivariate analysis of variance was performed to assess between group difference in pelvis, trunk, hip, and knee variables of interest. Runners with previous iliotibial band syndrome exhibited similar peak trunk lateral flexion, peak contralateral pelvic drop, peak hip adduction, and peak external knee adduction moment compared with controls. In addition, trunk-pelvis coordination was similar between groups. Contrary to our hypotheses, both groups exhibited trunk ipsilateral flexion. Lateral core endurance was not different between groups. These findings provide the first frontal plane pelvis and trunk kinematic data set in female runners with previous iliotibial band syndrome. Frontal plane pelvis and trunk motion may not be associated with iliotibial band syndrome.

The influence of iliotibial band syndrome history on running biomechanics examined via principal components analysis.

Iliotibial band syndrome (ITBS) is a common knee overuse injury among female runners. Atypical discrete trunk and lower extremity biomechanics during running may be associated with the etiology of ITBS. Examining discrete data points limits the interpretation of a waveform to a single value. Characterizing entire kinematic and kinetic waveforms may provide additional insight into biomechanical factors associated with ITBS. Therefore, the purpose of this cross-sectional investigation was to determine whether female runners with previous ITBS exhibited differences in kinematics and kinetics compared to controls using a principal components analysis (PCA) approach. Forty participants comprised two groups: previous ITBS and controls. Principal component scores were retained for the first three principal components and were analyzed using independent t-tests. The retained principal components accounted for 93-99% of the total variance within each waveform. Runners with previous ITBS exhibited low principal component one scores for frontal plane hip angle. Principal component one accounted for the overall magnitude in hip adduction which indicated that runners with previous ITBS assumed less hip adduction throughout stance. No differences in the remaining retained principal component scores for the waveforms were detected among groups. A smaller hip adduction angle throughout the stance phase of running may be a compensatory strategy to limit iliotibial band strain. This running strategy may have persisted after ITBS symptoms subsided.

Agreement between weight bearing and non-weight bearing joint position replication tasks at the knee and hip.

Peak joint angles assumed during the stance phase of running may indicate a runner's ability to sense limb position in space. Joint position sense can be assessed through weight bearing and non-weight bearing tasks. The purpose of this investigation was to determine if weight bearing and non-weight bearing knee and hip joint replication tasks elicited similar joint position sense test results. Absolute replication error was measured during sagittal plane knee and frontal plane hip conditions on 23 healthy runners. Three-dimensional kinematics was recorded during running. Intraclass correlation coefficients (ICCs) determined agreement between the two measures of joint position sense. Pearson's correlation coefficients measured the relationship between hip and knee absolute error and peak joint angles during running. Despite similar mean absolute error, ICCs indicated low agreement between weight bearing and non-weight bearing conditions at each joint. The results indicate the tests are not interchangeable. Absolute error for non-weight bearing hip replication was correlated with peak stance hip adduction during running. Weight bearing and non-weight bearing joint position sense tasks within the knee and hip joints measure joint position sense differently. Therefore, a task that is relevant to the activity of interest should be selected to measure joint position sense.

Lower extremity joint position sense in runners with and without a history of knee overuse injury.

Kinematic and kinetic analyses are routinely implemented to determine if gait differences exist between runners with and without a history of knee injury. Hip and knee kinematic differences have been reported between knee injured and non-injured runners. Yet, there is no consensus on whether these differences are the primary variables contributing to knee injury. Furthermore, there may be additional underlying factors that contribute to the development of injury that cannot be determined by gait analysis. The purpose of this investigation was to determine if joint position sense differences exist in runners with and without a history of knee overuse injury. Sagittal plane knee and hip joint position sense was measured in 13 runners with a history of knee overuse injury and 13 runners with no history of knee overuse injury. Absolute joint position replication error was measured during both a weight bearing and a non-weight bearing condition. Joint position replication errors at each joint were compared among groups and task using a two-way ANOVA with joint task as the repeated measure. Knee and hip joint replication errors were similar between both groups. The weight bearing and non-weight bearing tasks resulted in similar joint position replication errors. There were no interaction effects. In conclusion, knee flexion and hip adduction joint position sense is similar in runners with and without a history of knee overuse injury. Therefore, joint position sense measured via weight bearing and non-weight bearing joint position replication tasks may not play an important role in the development of knee overuse injury.