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1.  Kinematic Changes During a Marathon for Fast and Slow Runners 
The purpose of this study was to describe kinematic changes that occur during an actual marathon. We hypothesized that (1) certain running kinematic measures would change between kilometres 8 and 40 (miles 5 and 25) of a marathon and (2) fast runners would demonstrate smaller changes than slow runners. Subjects (n = 179) were selected according to finish time (Range = 2:20:47 to 5:30:10). Two high-speed cameras were used to measure sagittal-plane kinematics at kilometres 8 and 40 of the marathon. The dependent variables were stride length, contact time, peak knee flexion during support and swing, and peak hip flexion and extension during swing. Two-tailed paired t-tests were used to compare dependent variables between kilometres 8 and 40 for all subjects, and regression analyses were used to determine whether faster runners exhibited smaller changes (between miles 5 and 25) than slower runners. For all runners, every dependent variable changed significantly between kilometres 8 and 40 (p < 0.001). Stride length increased 1.3%, contact time increased 13.1%, peak knee flexion during support decreased 3.2%, and peak hip extension, knee flexion, and hip flexion during swing decreased 27.9%, increased 4.3%, and increased 7.4%, respectively (p < 0.001). Among these significant changes, all runners generally changed the same from kilometres 8 and 40 except that fast runners decreased peak knee flexion during support less than the slow runners (p < 0.002). We believe that these changes, for all runners (fast and slow), were due to fatigue. The fact that fast runners maintained knee flexion during support more consistently might be due to their condition on the race day. Strengthening of knee extensor muscles may facilitate increased knee flexion during support throughout a marathon.
Key points
Runners changed kinematics significantly from kilometres 8 to 40 (increased stride length, contact time, peak hip flexion during swing, and peak knee flexion during swing, and decreased running speed, stride frequency, peak knee flexion during support and peak hip extension during swing).
Fast runners demonstrated more peak knee flexion during support throughout a marathon.
Runners generally changed kinematics similarly (between kilometres 8 and 40) except that fast runners exhibited a more consistent peak knee flexion during support than slow runners.
Resistance training that would increase both muscular strength and endurance of knee extensors may increase peak knee flexion during support and help maintain it similar to the fast runners throughout a marathon.
PMCID: PMC3737836  PMID: 24137065
Fatigue; endurance; run; biomechanics; race
2.  REDUCED HIP STRENGTH IS ASSOCIATED WITH INCREASED HIP MOTION DURING RUNNING IN YOUNG ADULT AND ADOLESCENT MALE LONG‐DISTANCE RUNNERS 
Study Design:
Controlled laboratory study.
Background and Purpose:
Anterior knee pain is one of the most common running symptoms reported in the literature. While the exact etiology is unknown, a lack of hip strength is suggested to contribute to abnormal running mechanics. The purpose of this research study was to evaluate the association between isokinetic hip strength and 3‐D running kinematics.
Methods:
33 male high school and collegiate cross country runners participated in this study. Peak isokinetic hip abductor and hip extensor strength were assessed. Each subject also completed a treadmill running protocol at a self‐selected speed (mean = 3.8 m/s). 3‐D kinematic data were collected at 240 Hz using a 10‐camera motion capture system. Pearson correlation coefficients were used to determine the relationship between hip strength and hip range of motion (ROM) during the stance phase of running (p<0.05).
Results:
Peak isokinetic hip extensor torque was inversely correlated with transverse plane hip ROM (r = −.387, p = .026) but was not significantly related to sagittal plane hip ROM or frontal plane hip ROM. Peak isokinetic hip abductor torque was inversely correlated with frontal plane hip ROM (r=−.462, p=.008) but was not significantly related to either sagittal plane hip ROM or transverse plane hip ROM. Peak isokinetic hip extensor torque and peak isokinetic hip abductor torque were not significantly related to knee kinematics in any plane.
Conclusions:
Peak isokinetic hip extensor torque and peak isokinetic hip abductor torque are associated with transverse plane and frontal plane hip kinematics, but not knee kinematics.
Levels of Evidence:
Level 3b
PMCID: PMC4127508  PMID: 25133074
cross country; hip strength; isokinetic testing; running biomechanics.
3.  EFFECTS OF A MOVEMENT TRAINING PROGRAM ON HIP AND KNEE JOINT FRONTAL PLANE RUNNING MECHANICS 
Background/Purpose:
Frontal plane running mechanics may contribute to the etiology or exacerbation of common running related injuries. Hip strengthening alone may not change frontal plane hip and knee joint running mechanics. The purpose of the current study was to evaluate whether a training program including visual, verbal, and tactile feedback affects hip and knee joint frontal plane running mechanics among females with evidence of altered weight bearing kinematics.
Methods:
The knee frontal plane projection angle of 69 apparently healthy females was determined during a single leg squat. The twenty females from this larger sample who exhibited the most acute frontal plane projection angle (medial knee position) during this activity were chosen to participate in this study (age = 20 ± 1.6 years, height = 167.9 ± 6.0 cm, mass = 63.2 ± 8.3 kg, Tegner Activity Rating mode = 7.0). Participants engaged in a 4‐week movement training program using guided practice during weight bearing exercises with visual, verbal, and tactile feedback regarding lower extremity alignment. Paired t‐tests were used to compare frontal plane knee and hip joint angles and moments before and after the training program.
Results:
After training, internal hip and knee abduction moments during running decreased by 23% (P=0.007) and 29% (P=0.033) respectively. Knee adduction and abduction excursion decreased by 2.1° (P = 0.050) and 2.7° (P=0.008) respectively, suggesting that less frontal plane movement of the knee occurred during running after training. Peak knee abduction angle decreased 1.8° after training (P=0.051) although this was not statistically significant. Contralateral peak pelvic drop, pelvic drop excursion, peak hip adduction angle, hip adduction excursion, and peak knee adduction angle were unchanged following training.
Conclusions:
A four week movement training program may reduce frontal plane hip and knee joint mechanics thought to contribute to the etiology and exacerbation of some running related injuries.
Level of Evidence:
Level 4
PMCID: PMC3537459  PMID: 23316427
female; kinematics; kinetics; neuromuscular training; rehabilitation
4.  Lower Limb Kinematics and Dynamic Postural Stability in Anterior Cruciate Ligament-Reconstructed Female Athletes 
Journal of Athletic Training  2013;48(2):172-185.
Context:
Deficits in lower limb kinematics and postural stability are predisposing factors to the development of knee ligamentous injury. The extent to which these deficits are present after anterior cruciate ligament (ACL) reconstruction is still largely unknown.
The primary hypothesis of the present study was that female athletes who have undergone ACL reconstruction and who have returned to sport participation would exhibit deficits in dynamic postural stability as well as deficiencies in hip- and knee-joint kinematics when compared with an age-, activity-, and sex-matched uninjured control group.
Objective:
To investigate dynamic postural stability as quantified by the Star Excursion Balance Test (SEBT) and simultaneous hip- and knee-joint kinematic profiles in female athletes who have undergone ACL reconstruction.
Design:
Descriptive laboratory study.
Setting:
University motion-analysis laboratory.
Patients or Other Participants:
Fourteen female athletes who had previously undergone ACL reconstruction (ACL-R) and 17 age- and sex-matched uninjured controls.
Intervention(s):
Each participant performed 3 trials of the anterior, posterior-medial, and posterior-lateral directional components of the SEBT.
Main Outcome Measure(s):
Reach distances for each directional component were quantified and expressed as a percentage of leg length. Simultaneous hip- and knee-joint kinematic profiles were recorded using a motion-analysis system.
Results:
The ACL-R group had decreased reach distances on the posterior-medial (P < .01) and posterior-lateral (P < .01) directional components of the SEBT. During performance of the directional components of the SEBT, ACL-R participants demonstrated altered hip-joint frontal-, sagittal-, and transverse-plane kinematic profiles (P < .05), as well as altered knee-joint sagittal-plane kinematic profiles (P < .05).
Conclusions:
Deficits in dynamic postural stability and concomitant altered hip- and knee-joint kinematics are present after ACL reconstruction and return to competitive activity. The extent to which these deficits influence potential future injury is worthy of investigation.
doi:10.4085/1062-6050-48.2.05
PMCID: PMC3600919  PMID: 23672381
anterior cruciate ligament; reconstruction; kinematics; postural stability
5.  Do novice runners have weak hips and bad running form? 
Gait & posture  2014;40(1):82-86.
First, we sought to better understand the predisposition of novice female runners to injury by identifying potential differences in running mechanics and strength between experienced female runners and active novice runners. Secondly, we aimed to assess the relationship between hip and trunk strength with non-sagittal hip kinematics during running. Two female populations were recruited: 19 healthy experienced runners and 19 healthy active novice runners. Strength measurements of the hip abductors and external rotators were measured using a hand held dynamometer while trunk endurance was assessed via a side-plank. Next, an instrumented gait analysis was performed while each participant ran at 3.3 m/s. Group comparisons were made using an independent t-test to identify differences in the impact peak, loading rate, peak non-sagittal hip joint angles, trunk endurance, and hip strength. Pearson’s correlation coefficients were calculated between hip kinematics and strength measurements. There were no statistically significant differences in impact peak, loading rate, peak non-sagittal hip kinematics, or strength. However, the novice runners did show a clinically meaningful trend towards increased peak hip internal rotation by 3.8 degrees (effect size 0.520). A decrease in trunk side-plank endurance was associated with an increased peak hip internal rotation angle (r=−.357, p=0.03), whereas isometric strength was not related to kinematics. Programs aiming to prevent injuries in novice runners should target trunk performance and possibly hip neuromuscular control, rather than hip strength.
doi:10.1016/j.gaitpost.2014.02.014
PMCID: PMC4258689  PMID: 24656715
hip strength; side-plank; impact peak; loading rate; non-sagittal hip kinematics
6.  LIMITED HIP AND KNEE FLEXION DURING LANDING IS ASSOCIATED WITH INCREASED FRONTAL PLANE KNEE MOTION AND MOMENTS 
Background
It has been proposed that female athletes who limit knee and hip flexion during athletic tasks rely more on the passive restraints in the frontal plane to deceleration their body center of mass. This biomechanical pattern is thought to increase the risk for anterior cruciate ligament injury. To date, the relationship between sagittal plane kinematics and frontal plane knee motion and moments has not been explored.
Methods
Subjects consisted of fifty-eight female club soccer players (age range: 11 to 20 years) with no history of knee injury. Kinematics, ground reaction forces, and surface electromyography were collected while each subject performed a drop landing task. Subjects were divided into two groups based on combined sagittal plane knee and hip flexion angles during the deceleration phase of landing (high flexion and low flexion).
Findings
Subjects in the low flexion group demonstrated increased knee valgus angles (P = 0.02, effect size 0.27), increased knee adductor moments (P = 0.03, effect size 0.24), decreased energy absorption at the knee and hip (P = 0.02, effect size 0.25; and P< 0.001, effect size 0.59), and increased vastus lateralis EMG when compared to subjects in the high flexion group (P = 0.005, effect size 0.35).
Interpretation
Female athletes with limited sagittal plane motion during landing exhibit a biomechanical profile that may put these individuals at greater risk for anterior cruciate ligament injury.
doi:10.1016/j.clinbiomech.2009.10.005
PMCID: PMC2815098  PMID: 19913961
ACL; Injury Prevention; Joint Moments; Stiff Landing
7.  GENDER DIFFERENCES IN TRUNK, PELVIS AND LOWER LIMB KINEMATICS DURING A SINGLE LEG SQUAT 
Gait & posture  2012;36(3):461-466.
The relationship between trunk and lower limb kinematics in healthy females versus males is unclear since trunk kinematics in the frontal and transverse planes have not been systematically examined with lower limb kinematics. The aim of this study was to investigate the existence of different multi-joints movement strategies between genders during a single leg squat. We expected that compared to males, females would have greater trunk and pelvis displacement due to less trunk control and display hip and knee movement consistent with medial-collapse (i.e. greater hip adduction, hip medial rotation, knee abduction, knee lateral rotation) on the weight-bearing limb.
9 females and 10 males participated in the study. Kinematic data were collected using an 8-camera, 3D-motion-capture-system. Trunk relative to pelvis, pelvis relative to the laboratory, hip and knee angles in three planes (sagittal, frontal and transverse) were examined at two time events relevant to knee joint mechanics: 45° of knee flexion and peak knee flexion. Females flexed their trunk less than males and rotated their trunk and pelvis toward the weight-bearing limb more than males. Females also displayed greater hip adduction and knee abduction than males.
Taken together these results suggest that females and males used different movement strategies during a single leg squat. Females displayed a trunk and pelvic movement pattern that may put them at risk of knee injury and pain.
doi:10.1016/j.gaitpost.2012.04.006
PMCID: PMC3407338  PMID: 22591790
8.  Acute Lower Extremity Running Kinematics After a Hamstring Stretch 
Journal of Athletic Training  2012;47(1):5-14.
Context:
Limited passive hamstring flexibility might affect kinematics, performance, and injury risk during running. Pre-activity static straight-leg raise stretching often is used to gain passive hamstring flexibility.
Objective:
To investigate the acute effects of a single session of passive hamstring stretching on pelvic, hip, and knee kinematics during the swing phase of running.
Design:
Randomized controlled clinical trial.
Setting:
Biomechanics research laboratory.
Patients or Other Participants:
Thirty-four male (age = 21.2 ± 1.4 years) and female (age = 21.3±2.0 years) recreational athletes.
Intervention(s):
Participants performed treadmill running pretests and posttests at 70% of their age-predicted maximum heart rate. Pelvis, hip, and knee joint angles during the swing phase of 5 consecutive gait cycles were collected using a motion analysis system. Right and left hamstrings of the intervention group participants were passively stretched 3 times for 30 seconds in random order immediately after the pretest. Control group participants performed no stretching or movement between running sessions.
Main Outcome Measure(s):
Six 2-way analyses of variance to determine joint angle differences between groups at maximum hip flexion and maximum knee extension with an α level of .008.
Results:
Flexibility increased between pretest and post-test in all participants (F1,30 = 80.61, P<.001). Anterior pelvic tilt (F1,30 = 0.73, P=.40), hip flexion (F1,30 = 2.44, P=.13), and knee extension (F1,30 = 0.06, P=.80) at maximum hip flexion were similar between groups throughout testing. Anterior pelvic tilt (F1,30 = 0.69, P=.41), hip flexion (F1,30 = 0.23, P=.64), and knee extension (F1,30 = 3.38, P=.62) at maximum knee extension were similar between groups throughout testing. Men demonstrated greater anterior pelvic tilt than women at maximum knee extension (F1,30 = 13.62, P=.001).
Conclusions:
A single session of 3 straight-leg raise hamstring stretches did not change pelvis, hip, or knee running kinematics.
PMCID: PMC3418114  PMID: 22488225
straight-leg raises; flexibility
9.  Instruction and Jump-Landing Kinematics in College-Aged Female Athletes Over Time 
Journal of Athletic Training  2013;48(2):161-171.
Context:
Instruction can be used to alter the biomechanical movement patterns associated with anterior cruciate ligament (ACL) injuries.
Objective:
To determine the effects of instruction through combination (self and expert) feedback or self-feedback on lower extremity kinematics during the box–drop-jump task, running–stop-jump task, and sidestep-cutting maneuver over time in college-aged female athletes.
Design:
Randomized controlled clinical trial.
Setting:
Laboratory.
Patients or Other Participants:
Forty-three physically active women (age = 21.47 ± 1.55 years, height = 1.65 ± 0.08 m, mass = 63.78 ± 12.00 kg) with no history of ACL or lower extremity injuries or surgery in the 2 months before the study were assigned randomly to 3 groups: self-feedback (SE), combination feedback (CB), or control (CT).
Intervention(s):
Participants performed a box–drop-jump task for the pretest and then received feedback about their landing mechanics. After the intervention, they performed an immediate posttest of the box–drop-jump task and a running–stop-jump transfer test. Participants returned 1 month later for a retention test of each task and a sidestep-cutting maneuver. Kinematic data were collected with an 8-camera system sampled at 500 Hz.
Main Outcome Measure(s):
The independent variables were feedback group (3), test time (3), and task (3). The dependent variables were knee- and hip-flexion, knee-valgus, and hip- abduction kinematics at initial contact and at peak knee flexion.
Results:
For the box–drop-jump task, knee- and hip-flexion angles at initial contact were greater at the posttest than at the retention test (P < .001). At peak knee flexion, hip flexion was greater at the posttest than at the pretest (P = .003) and was greater at the retention test than at the pretest (P = .04); knee valgus was greater at the retention test than at the pretest (P = .03) and posttest (P = .02). Peak knee flexion was greater for the CB than the SE group (P = .03) during the box–drop-jump task at posttest. For the running–stop-jump task at the posttest, the CB group had greater peak knee flexion than the SE and CT (P ≤ .05).
Conclusions:
Our results suggest that feedback involving a combination of self-feedback and expert video feedback with oral instruction effectively improved lower extremity kinematics during jump-landing tasks.
doi:10.4085/1062-6050-48.2.09
PMCID: PMC3600918  PMID: 23672380
augmented feedback; technique instruction; box-drop jump; running-stop jump; sidestep-cutting maneuver
10.  Athletic Footwear, Leg Stiffness, and Running Kinematics 
Journal of Athletic Training  2006;41(4):387-392.
Context: The leg acts as a linear spring during running and hopping and adapts to the stiffness of the surface, maintaining constant total stiffness of the leg-surface system. Introducing a substance (eg, footwear) may affect the stiffness of the leg in response to changes in surface stiffness.
Objective: To determine if the type of athletic footwear affects the regulation of leg stiffness in dynamic activities.
Design: Repeated-measures design.
Setting: Motion analysis laboratory.
Patients or Other Participants: Nine healthy adults (age = 28 ± 6.8 years, mass = 71.6 ± 12.9 kg) free from lower extremity injuries.
Intervention(s): Subjects hopped at 2.2 Hz on a forceplate under 3 footwear conditions (barefoot, low-cost footwear, high-cost footwear). Subjects ran on a treadmill at 2 speeds (2.23 m/s, 3.58 m/s) under the same footwear conditions.
Main Outcome Measure(s): Limb stiffness was calculated from forceplate data. Kinematic data (knee and ankle angles at initial contact and peak joint excursion after contact) were collected during running. We calculated 1-way repeated-measures (stiffness) and 2-way (speed by footwear) repeated-measures analyses of variance (running kinematics) to test the dependent variables.
Results: A significant increase in leg stiffness from the barefoot to the “cushioned” shoe condition was noted during hopping. When running shod, runners landed in more dorsiflexion but had less ankle motion than when running barefoot. No differences were seen between the types of shoes. The primary kinematic difference was identified as running speed increased: runners landed in more knee flexion. At the ankle, barefoot runners increased ankle motion to a significantly greater extent than did shod runners as speed increased.
Conclusions: Footwear influences the maintenance of stiffness in the lower extremity during hopping and joint excursion at the ankle in running. Differences in cushioning properties of the shoes tested did not appear to be significant.
PMCID: PMC1748411  PMID: 17273463
shoes; gait; hopping task
11.  Structure, Sex, and Strength and Knee and Hip Kinematics During Landing 
Journal of Athletic Training  2011;46(4):376-385.
Context:
Researchers have observed that medial knee collapse is a mechanism of knee injury. Lower extremity alignment, sex, and strength have been cited as contributing to landing mechanics.
Objective:
To determine the relationship among measurements of asymmetry of unilateral hip rotation (AUHR); mobility of the foot, which we described as relative arch deformity (RAD); hip abduction–external rotation strength; sex; and me-dial collapse of the knee during a single-leg jump landing. We hypothesized that AUHR and RAD would be positively correlated with movements often associated with medial collapse of the knee, including hip adduction and internal rotation excursions and knee abduction and rotation excursions.
Design:
Descriptive laboratory study.
Setting:
Research laboratory.
Patients or Other Participants:
Thirty women and 15 men (age = 21 ± 2 years, height = 171.7 ± 9.5 cm, mass = 68.4 ± 9.5 kg) who had no history of surgery or recent injury and who participated in regular physical activity volunteered.
Interventions :
Participants performed 3 double-leg forward jumps with a single-leg landing. Three-dimensional kinematic data were sampled at 100 Hz using an electromagnetic tracking system. We evaluated AUHR and RAD on the preferred leg and evaluated isometric peak hip abductor–external rotation torque. We assessed AUHR by calculating the difference between internal and external hip rotation in the prone position (AUHR = internal rotation – external rotation). We evaluated RAD using the Arch Height Index Measurement System. Correlations and linear regression analyses were used to assess relationships among AUHR, RAD, sex, peak hip abduction–external rotation torque, and kinematic variables for 3-dimensional motion of the hip and knee.
Main Outcome Measure(s):
The dependent variables were joint angles at contact and joint excursions between contact and peak knee flexion.
Results:
We found that AUHR was correlated with hip adduction excursion (R = 0.36, P = .02). Asymmetry of unilateral hip rotation, sex, and peak hip abduction–external rotation torque were predictive of knee abduction excursion (adjusted R2 = 0.47, P < .001). Asymmetry of unilateral hip rotation and sex were predictive of knee external rotation excursion (adjusted R2 = 0.23, P = .001). The RAD was correlated with hip adduction at contact (R2 = 0.10, R = 0.32, P = .04) and knee flexion excursion (R2 = 0.11, R = −0.34, P = .03).
Conclusions:
Asymmetry of unilateral hip rotation, sex, and hip strength were associated with kinematic components of medial knee collapse.
PMCID: PMC3419149  PMID: 21944069
anteversion; valgus; arch mobility; alignment; anterior cruciate ligament; biomechanics; lower extremity; risk factor; regression analysis
12.  Assessment of Strength, Flexibility, and Running Mechanics in Males with Iliotibial Band Syndrome 
Study Design
Cross-sectional laboratory study.
Objectives
To assess differences in hip strength, iliotibial band length, and hip and knee mechanics during running between male runners with iliotibial band syndrome and healthy controls.
Background
Flexibility, strength, and running mechanics are commonly assessed in patients with iliotibial band syndrome (ITBS). However, these variables have not been evaluated concurrently in this population.
Methods
Thirty-four males participated (17 healthy, 17 ITBS). Hip strength was measured with a hand held dynamometer and iliotibial band flexibility was assessed using an inclinometer while performing the Ober’s test. Kinetic and three-dimensional kinematic data were obtained during running. Kinematic variables of interest included frontal and transverse plane hip and knee joint angles at the time of early stance. Independent sample t-tests as well as effect sizes were used to assess group differences.
Results
Compared to the control group, persons with ITBS had a significantly lower Ober’s measurement (1.2°), weaker hip external rotators (1.2 Nm/kg), greater hip internal rotation (3.7°), and greater knee adduction (3.6°). However, only hip internal rotation and knee adduction exceeded the minimal detectable change score.
Conclusions
Our results suggest that intervention strategies that target neuromuscular control of the hip and knee may be indicated for males with iliotibial band syndrome.
doi:10.2519/jospt.2014.4991
PMCID: PMC4258688  PMID: 24450366
hip and knee mechanics; hip strength; Ober’s test; running
13.  Proximal and Distal Kinematics in Female Runners with Patellofemoral Pain 
Background
Female runners have a high incidence of developing patellofemoral pain. Abnormal mechanics are thought to be an important contributing factor to patellofemoral pain. However, the contribution of abnormal trunk, hip, and foot mechanics to the development of patellofemoral pain within this cohort remains elusive. Therefore the aim of this study was to determine if significant differences during running exist in hip, trunk and foot kinematics between females with and without patellofemoral pain.
Methods
32 female runners (16 patellofemoral pain, 16 healthy control) participated in this study. All individuals underwent an instrumented gait analysis. Between-group comparisons were made for hip adduction, hip internal rotation, contra-lateral pelvic drop, contra-lateral trunk lean, rearfoot eversion, tibial internal rotation, as well as forefoot dorsiflexion and abduction
Findings
The patellofemoral pain group had significantly greater peak hip adduction and hip internal rotation. No differences in contra-lateral pelvic drop were found. A trend towards reduced contra-lateral trunk lean was found in the patellofemoral pain group. No significant differences were found in any of the rearfoot or forefoot variables but significantly greater shank internal rotation was found in the patellofemoral pain group.
Interpretation
We found greater hip adduction, hip internal rotation and shank internal rotation in female runners with patellofemoral pain. We also found less contra-lateral trunk lean in the patellofemoral pain group. This may be a potential compensatory mechanism for the poor hip Control seen. Rehabilitation programs that correct abnormal hip and shank kinematics are warranted in this population.
doi:10.1016/j.clinbiomech.2011.10.005
PMCID: PMC3984468  PMID: 22071426
14.  Comparison of Lower Extremity Kinematic Curves During Overground and Treadmill Running 
Journal of Applied Biomechanics  2010;26(4):407-414.
Researchers conduct gait analyses utilizing both overground and treadmill modes of running. Previous studies comparing these modes analyzed discrete variables. Recently, techniques involving quantitative pattern analysis have assessed kinematic curve similarity in gait. Therefore, the purpose of this study was to compare hip, knee and rearfoot 3-D kinematics between overground and treadmill running using quantitative kinematic curve analysis. Twenty runners ran at 3.35 m/s ± 5% during treadmill and overground conditions while right lower extremity kinematics were recorded. Kinematics of the hip, knee and rearfoot at footstrike and peak were compared using intraclass correlation coefficients. Kinematic curves during stance phase were compared using the trend symmetry method within each subject. The overall average trend symmetry was high, 0.94 (1.0 is perfect symmetry) between running modes. The transverse plane and knee frontal plane exhibited lower similarity (0.86–0.90). Other than a 4.5 degree reduction in rearfoot dorsiflexion at footstrike during treadmill running, all differences were ≤1.5 degrees. 17/18 discrete variables exhibited modest correlations (>0.6) and 8/18 exhibited strong correlations (>0.8). In conclusion, overground and treadmill running kinematic curves were generally similar when averaged across subjects. Although some subjects exhibited differences in transverse plane curves, overall, treadmill running was representative of overground running for most subjects.
PMCID: PMC3266869  PMID: 21245500
biomechanics; gait; waveform comparison
15.  The Effects of Fatigue and Chronic Ankle Instability on Dynamic Postural Control 
Journal of Athletic Training  2004;39(4):321-329.
Objective: Deficits in static postural control related to chronic ankle instability (CAI) and fatigue have been investigated separately, but little evidence links these factors to performance of dynamic postural control. Our purpose was to investigate the effects of fatigue and CAI on performance measures of a dynamic postural-control task, the Star Excursion Balance Test.
Design and Setting: For each of the 3 designated reaching directions, 4 separate 5 (condition) × 2 (time) × 2 (side) analyses of variance with a between factor of group (CAI, healthy) were calculated for normalized reach distance and maximal ankle-dorsiflexion, knee-flexion, and hip-flexion angles. All data were collected in the Athletic Training Research Laboratory.
Subjects: Thirty subjects (16 healthy, 14 CAI) participated.
Measurements: All subjects completed 5 testing sessions, during which sagittal-plane kinematics and reaching distances were recorded while they performed 3 reaching directions (anterior, medial, and posterior) of the Star Excursion Balance Test, with the same stance leg before and after different fatiguing conditions. The procedure was repeated for both legs during each session.
Results: The involved side of the CAI subjects displayed significantly smaller reach distance values and knee-flexion angles for all 3 reaching directions compared with the uninjured side and the healthy group. The effects of fatigue amplified this trend.
Conclusions: Chronic ankle instability and fatigue disrupted dynamic postural control, most notably by altering control of sagittal-plane joint angles proximal to the ankle.
PMCID: PMC535524  PMID: 15592604
Star Excursion Balance Test; lower extremity; neuromuscular control
16.  Sagittal plane gait characteristics in hip osteoarthritis patients with mild to moderate symptoms compared to healthy controls: a cross-sectional study 
Background
Existent biomechanical studies on hip osteoarthritic gait have primarily focused on the end stage of disease. Consequently, there is no clear consensus on which specific gait parameters are of most relevance for hip osteoarthritis patients with mild to moderate symptoms. The purpose of this study was to explore sagittal plane gait characteristics during the stance phase of gait in hip osteoarthritis patients not eligible for hip replacement surgery. First, compared to healthy controls, and second, when categorized into two subgroups of radiographic severity defined from a minimal joint space of ≤/>2 mm.
Methods
Sagittal plane kinematics and kinetics of the hip, knee and ankle joint were calculated for total joint excursion throughout the stance phase, as well as from the specific events initial contact, midstance, peak hip extension and toe-off following 3D gait analysis. In addition, the Western Ontario and McMaster Universities Osteoarthritis Index, passive hip range of motion, and isokinetic muscle strength of hip and knee flexion and extension were included as secondary outcomes. Data were checked for normality and differences evaluated with the independent Student’s t-test, Welch’s t-test and the independent Mann–Whitney U-test. A binary logistic regression model was used in order to control for velocity in key variables.
Results
Fourty-eight hip osteoarthritis patients and 22 controls were included in the final material. The patients walked significantly slower than the controls (p=0.002), revealed significantly reduced joint excursions of the hip (p<0.001) and knee (p=0.011), and a reduced hip flexion moment at midstance and peak hip extension (p<0.001). Differences were primarily manifested during the latter 50% of stance, and were persistent when controlling for velocity. Subgroup analyses of patients with minimal joint space ≤/>2 mm suggested that the observed deviations were more pronounced in patients with greater radiographic severity. The biomechanical differences were, however, not reflected in self-reported symptoms or function.
Conclusions
Reduced gait velocity, reduced sagittal plane joint excursion, and a reduced hip flexion moment in the late stance phase of gait were found to be evident already in hip osteoarthritis patients with mild to moderate symptoms, not eligible for total hip replacement. Consequently, these variables should be considered as key features in studies regarding hip osteoarthritic gait at all stages of disease. Subgroup analyses of patients with different levels of radiographic OA further generated the hypothesis that the observed characteristics were more pronounced in patients with a minimal joint space ≤2 mm.
doi:10.1186/1471-2474-13-258
PMCID: PMC3542161  PMID: 23256709
Osteoarthritis; Hip; Biomechanics; Gait analysis
17.  Hip Abductor Function and Lower Extremity Landing Kinematics: Sex Differences 
Journal of Athletic Training  2007;42(1):76-83.
Context: Rapid deceleration during sporting activities, such as landing from a jump, has been identified as a common mechanism of acute knee injury. Research into the role of potential sex differences in hip abductor function with lower extremity kinematics when landing from a jump is limited.
Objective: To evaluate sex differences in hip abductor function in relation to lower extremity landing kinematics.
Design: 2 × 2 mixed-model factorial design using a between-subjects factor (sex) and a repeated factor (test).
Setting: University laboratory.
Patients or Other Participants: A sample of convenience consisting of 30 healthy adults (15 women, 15 men) with no history of lower extremity surgery and no lower extremity injuries within 6 months of testing.
Intervention(s): Landing kinematics were assessed as subjects performed 3 pre-exercise landing trials that required them to hop from 2 legs and land on a single leg. Isometric peak torque (PT) of the hip abductors was measured, followed by an endurance test during which subjects maintained 50% of their PT to the limits of endurance. After a 15-minute rest period, subjects completed a 30-second bout of isometric hip abduction, from which we calculated the percentage of endurance capacity (%E). Immediately after exercise, subjects completed 3 postexercise landing trials.
Main Outcome Measure(s): PT, %E, and peak joint displacement (PJD) of the hip and knee in all 3 planes of motion.
Results: Women demonstrated lower PT values (5.8 ± 1.2% normalized to body weight and height) than did their male counterparts (7.2 ± 1.5% normalized to body weight and height, P = .009). However, no sex differences were seen in %E. Women also demonstrated larger knee valgus PJD (7.26° ± 6.61°) than did men (3.29° ± 3.54°, P = .04). Women's PT was moderately correlated with hip flexion, adduction, and knee valgus PJD; however, PT did not significantly correlate with men's landing kinematics. Regardless of sex, hip flexion (P = .002) and hip adduction (P = .001) were significantly increased following the 30-second bout of exercise.
Conclusions: Women demonstrated lower hip abductor PT and increased knee valgus PJD when landing from a jump, potentially increasing the risk of acute knee injury. Furthermore, correlations between hip abductor strength and landing kinematics were generally larger for women than for men, suggesting that hip abductor strength may play a more important role in neuromuscular control of the knee for women.
PMCID: PMC1896084  PMID: 17597947
biomechanics; knee; torque; motion analysis
18.  Bone mineral density and serum testosterone in chronically trained, high mileage 40–55 year old male runners 
Objectives—To identify physical activity that is beneficial for the maintenance of bone strength with increasing age by examining the relation between bone mineral density (BMD) and chronic endurance training in men. BMD at the proximal femur, its subregions, and the lumbar spine, and serum testosterone were compared between two groups of long distance runners with more than 20 years of training experience and non-athletic controls.
Methods—Runners (n = 12) were divided into (a) high volume runners (n = 7), running 64–80 km a week, and (b) very high volume runners (n = 5), running more than 95 km a week, and compared with non-athletic male controls, exercising in non-endurance oriented activities two to four times a week. BMD (g/cm2) at the total proximal femur, femoral neck, trochanteric region, and lumbar spine was measured by dual energy x ray absorptiometry. Total testosterone (nmol/l) and free testosterone (pmol/l) in serum were measured by radioimmunoassay from single fasting blood samples.
Results—Height, weight, and age (range = 40–55 years) were not significantly different between groups. The high volume runners had significantly higher BMD at the total proximal femur (1.09 (0.17) v 0.94 (0.056)), femoral neck (0.91 (0.16) v 0.78 (0.071)), and trochanteric region (0.85 (0.14) v 0.73 (0.053)) than controls (p<0.05). The differences in BMD for the proximal femur between the very high volume runners and the other two groups were not significant. There was no difference in lumbar spine BMD, total testosterone, or free testosterone between groups. However, there was a significant negative correlation between total testosterone (r = -0.73, p<0.01) and free testosterone (r = -0.79, p<0.005) and running volume in the distance runners.
Conclusions—Long term distance running with training volumes less than 80 km a week had a positive effect on BMD of the proximal femur. With running volumes greater than 64 km a week, training was inversely related to testosterone levels, but levels remained within the normal range.
Key Words: exercise; bone mineral density; male athletes; runners; endurance training; testosterone
doi:10.1136/bjsm.34.4.273
PMCID: PMC1724199  PMID: 10953900
19.  Changes in Knee Biomechanics After a Hip-Abductor Strengthening Protocol for Runners With Patellofemoral Pain Syndrome 
Journal of Athletic Training  2011;46(2):142-149.
Abstract
Context:
Very few authors have investigated the relationship between hip-abductor muscle strength and frontal-plane knee mechanics during running.
Objective:
To investigate this relationship using a 3-week hip-abductor muscle-strengthening program to identify changes in strength, pain, and biomechanics in runners with patellofemoral pain syndrome (PFPS).
Design:
Cohort study.
Setting:
University-based clinical research laboratory.
Patients or Other Participants:
Fifteen individuals (5 men, 10 women) with PFPS and 10 individuals without PFPS (4 men, 6 women) participated.
Intervention(s):
The patients with PFPS completed a 3-week hip-abductor strengthening protocol; control participants did not.
Main Outcome Measure(s):
The dependent variables of interest were maximal isometric hip-abductor muscle strength, 2-dimensional peak knee genu valgum angle, and stride-to-stride knee-joint variability. All measures were recorded at baseline and 3 weeks later. Between-groups differences were compared using repeated-measures analyses of variance.
Results:
At baseline, the PFPS group exhibited reduced strength, no difference in peak genu valgum angle, and increased stride-to-stride knee-joint variability compared with the control group. After the 3-week protocol, the PFPS group demonstrated increased strength, less pain, no change in peak genu valgum angle, and reduced stride-to-stride knee-joint variability compared with baseline.
Conclusions:
A 3-week hip-abductor muscle-strengthening protocol was effective in increasing muscle strength and decreasing pain and stride-to-stride knee-joint variability in individuals with PFPS. However, concomitant changes in peak knee genu valgum angle were not observed.
doi:10.4085/1062-6050-46.2.142
PMCID: PMC3070501  PMID: 21391799
gait; hip muscles; anterior knee pain
20.  Patellar Taping, Patellofemoral Pain Syndrome, Lower Extremity Kinematics, and Dynamic Postural Control 
Journal of Athletic Training  2008;43(1):21-28.
Context: Patellar taping has been a part of intervention for treatment of patellofemoral pain syndrome (PFPS). However, research on the efficacy of patellar taping on lower extremity kinematics and dynamic postural control is limited.
Objective: To evaluate the effects of patellar taping on sagittal-plane hip and knee kinematics, reach distance, and perceived pain level during the Star Excursion Balance Test (SEBT) in individuals with and without PFPS.
Design: Repeated-measures design with 2 within-subjects factors and 1 between-subjects factor.
Setting: The University of Toledo Athletic Training Research Laboratory.
Patients or Other Participants: Twenty participants with PFPS and 20 healthy participants between the ages of 18 and 29 years.
Intervention(s): The participants performed 3 reaches of the SEBT in the anterior direction under tape and no-tape conditions on both legs.
Main Outcome Measure(s): The participants' hip and knee sagittal-plane kinematics were measured using the electromagnetic tracking system. Reach distance was recorded by hand and was normalized by dividing the distance by the participants' leg length (%MAXD). After each taping condition on each leg, the participants rated the perceived pain level using the 10-cm visual analog scale.
Results: The participants with PFPS had a reduction in pain level with patellar tape application compared with the no-tape condition (P = .005). Additionally, participants with PFPS demonstrated increased %MAXD under the tape condition compared with the no-tape condition, whereas the healthy participants demonstrated decreased %MAXD with tape versus no tape (P = .028). No statistically significant differences were noted in hip flexion and knee flexion angles.
Conclusions: Although patellar taping seemed to reduce pain and improve SEBT performance of participants with PFPS, the exact mechanisms of these phenomena cannot be explained in this study. Further research is warranted to investigate the effect of patellar taping on neuromuscular control during dynamic postural control.
PMCID: PMC2231393  PMID: 18335009
anterior knee pain; McConnell taping
21.  Are mechanics different between male and female runners with patellofemoral pain? 
Introduction
Patellofemoral pain (PFP) has often been attributed to abnormal hip and knee mechanics in females. To date, there have been few investigations of the hip and knee mechanics of males with PFP. The purpose of this study was to compare the lower extremity mechanics and alignment of male runners with PFP with healthy male runners and female runners with PFP. We hypothesized that males with PFP would move with greater varus knee mechanics compared with male controls and compared with females with PFP. Further, it was hypothesized that males with PFP would demonstrate greater varus alignment.
Methods
A gait and single leg squat analysis was conducted on each group (18 runners per group). Measurement of each runner’s tibial mechanical axis was also recorded. Motion data were processed using Visual 3D (CMotion, Bethesda, Md., USA). Analyses of Variance were used to analyze the data.
Results
Males with PFP ran and squatted in greater peak knee adduction and demonstrated greater peak knee external adduction moment compared with healthy male controls. In addition, males with PFP ran and squatted with less peak hip adduction and greater peak knee adduction compared with females with PFP. The static measure of mechanical axis of the tibial was not different between groups. However, a post-hoc analysis revealed that males with PFP ran with greater peak tibial segmental adduction.
Conclusion
Males with PFP demonstrated different mechanics during running and during a single leg squat compared with females with PFP and with healthy males. Based upon the results of this study, therapies for PFP may need to be sex-specific.
doi:10.1249/MSS.0b013e3182629215
PMCID: PMC3475738  PMID: 22843103
Patellofemoral Pain; Running; Biomechanics; Sex Differences
22.  CHANGES IN LOWER EXTREMITY MOVEMENT AND POWER ABSORPTION DURING FOREFOOT STRIKING AND BAREFOOT RUNNING 
Purpose/Background:
Both forefoot strike shod (FFS) and barefoot (BF) running styles result in different mechanics when compared to rearfoot strike (RFS) shod running. Additionally, running mechanics of FFS and BF running are similar to one another. Comparing the mechanical changes occurring in each of these patterns is necessary to understand potential benefits and risks of these running styles. The authors hypothesized that FFS and BF conditions would result in increased sagittal plane joint angles at initial contact and that FFS and BF conditions would demonstrate a shift in sagittal plane joint power from the knee to the ankle when compared to the RFS condition. Finally, total lower extremity power absorption will be least in BF and greatest in the RFS shod condition.
Methods:
The study included 10 male and 10 female RFS runners who completed 3‐dimensional running analysis in 3 conditions: shod with RFS, shod with FFS, and BF. Variables were the angles of plantarflexion, knee flexion, and hip flexion at initial contact and peak sagittal plane joint power at the hip, knee, and ankle during stance phase.
Results:
Running with a FFS pattern and BF resulted in significantly greater plantarflexion and significantly less negative knee power (absorption) when compared to shod RFS condition. FFS condition runners landed in the most plantarflexion and demonstrated the most peak ankle power absorption and lowest knee power absorption between the 3 conditions. BF and FFS conditions demonstrated decreased total lower extremity power absorption compared to the shod RFS condition but did not differ from one another.
Conclusions:
BF and FFS running result in reduced total lower extremity power, hip power and knee power and a shift of power absorption from the knee to the ankle.
Clinical Relevance:
Alterations associated with BF running patterns are present in a FFS pattern when wearing shoes. Additionally, both patterns result in increased demand at the foot and ankle as compared to the knee.
PMCID: PMC3474309  PMID: 23091785
barefoot running; biomechanics; running; strike pattern
23.  Relation of anterior pelvic tilt during running to clinical and kinematic measures of hip extension 
Background—Limited hip extension flexibility due to tight hip flexor musculature or anterior hip capsular and ligamentous structures is a possible cause of increased anterior tilt of the pelvis during running. However, to date, research exploring this relation, as well as the kinematic relation between anterior tilt of the pelvis and peak hip extension range of motion during running, is not available.
Objective—To assess the relation of anterior pelvic tilt during running to peak hip extension range of motion measured during running and hip extension flexibility measured clinically.
Methods—Hip extension flexibility was assessed using the Thomas test, and the three dimensional kinematic motion of the pelvis and hips were recorded using a VICON motion analysis system with 14 elite athletes running on a treadmill at 20 km/h.
Results—Anterior pelvic tilt displayed a significant (p<0.01) correlation with peak hip extension range of motion during running. Anterior pelvic tilt tended to be increased in runners who displayed reduced absolute peak hip extension range of motion during terminal stance. No significant correlation was shown for hip extension flexibility with either anterior pelvic tilt or peak hip extension range of motion during running.
Conclusions—The outcomes of this study indicate that anterior pelvic tilt and hip extension are coordinated movements during running. Static hip extension flexibility measured using the modified Thomas test does not appear to be reflective of these dynamic movements.
Key Words: running; kinematics; pelvis; hip; flexibility
doi:10.1136/bjsm.34.4.279
PMCID: PMC1724219  PMID: 10953901
24.  Relationship Between Hip and Knee Kinematics In Athletic Women During Cutting Maneuvers: A Possible Link to Noncontact Anterior Cruciate Ligament Injury and Prevention 
The purposes of this study were to compare lower-extremity kinematics during a 45° and 90° cutting maneuver and to examine the relationships between lower-extremity rotations during these maneuvers. The hypotheses tested were that greater internal hip and knee rotation angles would be observed during the cutting maneuver at a 90° angle (90° cut) compared with the maneuver performed at a 45° angle (45° cut) and that the increased internal hip and knee rotation would be related to increased knee abduction measures. Nineteen athletes from women’s soccer teams (17.6 ± 2.1 yr, 165.6 ± 8.2 cm, 60.2 ± 5.6 kg) were instructed to jump across a line and cut at the appropriate angle (either 45° or 90° side-step cut) and in the appropriate direction. Lower-extremity kinematic measures were taken at peak force during the stance phase. Hip internal rotation and knee internal rotation (p = 0.008) were increased during the 90° cut compared with the 45° cut. Mean hip flexion (p < 0.001) was also greater in the 90° cut. The only significant predictor of knee abduction during both tasks was hip adduction (R = 0.49). The findings indicate that the mechanisms underlying increased knee abduction measures in athletic women during cutting tasks were primarily coronal plane motions at the hip. Trunk and hip focused strength neuromuscular training may improve the ability of athletic women to increase control of lower-extremity alignment. Therefore, these women may decrease dangerous knee loads that result from increased hip adduction during dynamic tasks, thus decreasing anterior cruciate ligament injury risk.
doi:10.1519/JSC.0b013e3181bc1a02
PMCID: PMC3565241  PMID: 19826304
female sports; knee injury prevention; high risk biomechanics; reaction cutting; agility
25.  The Influence of a Foot Orthotic on Lower Extremity Transverse Plane Kinematics in Collegiate Female Athletes with Pes Planus 
Non-contact anterior cruciate ligament (ACL) injuries in female athletes remain prevalent. Athletes with excessive foot pronation have been identified to be at greater risk for non-contact ACL injury. Excessive foot pronation has been linked to increased medial tibial rotation. Increased medial tibial rotation heightens ACL strain and has been observed at or near the time of ACL injury. Foot orthotics have been shown to decrease medial tibial rotation during walking and running tasks. The effect of a foot orthotic on activities that simulate a non-contact ACL injury mechanism (i.e. landing) however is unknown. Therefore, the objective of this study was to determine whether a foot orthotic was capable of altering transverse plane lower extremity kinematics in female athletes during landing. Twenty uninjured collegiate female athletes participating in the sports of basketball, soccer or volleyball with pes planus volunteered. Utilizing a repeated measures counterbalanced design, subjects completed two landing tasks with and without a foot orthotic using standardized footwear. The prefabricated orthotic had a rigid shell and a 6 extrinsic rear-foot varus post. Dependent measures included initial contact angle, peak angle, excursion and time to peak angle for both the tibia and femur. Statistical analysis suggested that the selected foot orthosis had little influence over lower extremity transverse plane kinematics. Several factors including: the limitation of a static measure to predict dynamic movement, inter-subject variability and the physical characteristics of the orthotic device likely account for the results. Future research should examine the influence of different types of foot orthotics not only on lower extremity kinematics but also tibiofemoral kinetics.
Key PointsLower extremity transverse plane kinematics in female athletes during a landing task exhibit substantial variability.A rigid prefabricated foot orthotic does not significantly alter transverse plane lower extremity kinematics in female athletes with a navicular drop of at least 8mm.Additional study is necessary before firm conclusions regarding the influence of an orthotic device on lower extremity kinematics, kinetics, neuromuscular control and ultimately injury rates can be made.
PMCID: PMC3861767  PMID: 24357961
ACL; hyperpronation; intervention; navicular drop; pes planus

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