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Lindsay Hunter, Quinette Abigail Louw and Sjan-Mari van Niekerk

Context:

Iliotibial-band syndrome (ITBS) is a common overuse running injury. There is inconclusive evidence to support current management strategies, and few advances have been made in the past few years. New management approaches should thus be developed and evaluated.

Objective:

To assess the effects of a real-time running-retraining program on lower-extremity biomechanics, pain while running, and function.

Design:

Single-subject experimental study.

Setting:

University motion-analysis laboratory.

Participant:

Female recreational runner with ITBS.

Intervention:

Nine real-time running-retraining sessions were implemented based on the biomechanical alterations of the participant's symptomatic lower limb, including pelvic and knee movement in the transverse plane, as well as foot movement in the frontal plane. Real-time visual feedback of the pelvic-rotation angle was provided during the running-retraining sessions.

Main Outcome Measurements:

3-dimensional lower-extremity running kinematics, pain on a verbal analog scale while running on a treadmill, and the Lower Extremity Functional Scale (LEFS).

Results:

Pelvic external rotation decreased, although the aim was to increase pelvic external rotation and knee rotation. The foot-progression angle improved after the intervention and at 1-mo follow-up. There was a 12.5% improvement in running time, and the pain score while running improved by 50% postintervention; these improvements were maintained at 1-mo follow-up. The mean LEFS score, indicative of function, improved by 8.75% and by 10% at the end of the intervention and at 1-mo follow-up, respectively.

Conclusion:

The real-time running-retraining program improved pain while running, as well as function, and was effective in addressing the lower-limb biomechanical alterations of the knee and foot in a female runner with ITBS. The application, effectiveness, and feasibility of real-time training should be addressed in larger studies in the future.

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Adam Culiver, J. Craig Garrison, Kalyssa M. Creed, John E. Conway, Shiho Goto and Sherry Werner

Context: Numerous studies have reported kinematic data on baseball pitchers using three-dimensional (3D) motion analysis, but no studies to date have correlated this data with clinical outcome measures. Objective: To examine the relationship among Y-Balance Test–Lower Quarter (YBT-LQ) composite scores, musculoskeletal characteristics of the hip, and pitching kinematics in National Collegiate Athletic Association (NCAA) Division I baseball pitchers. Design: Cross-sectional. Setting: 3D motion analysis laboratory. Participants: Nineteen healthy male college baseball pitchers. Main Outcome Measures: Internal and external hip passive range of motion, hip abduction strength, YBT-LQ composite scores, and kinematic variables of the pitching motion. Results: Stride length demonstrated a moderate positive correlation with dominant limb YBT-LQ composite score (r = .524, P = .02) and nondominant limb YBT-LQ composite score (r = .550, P = .01), and a weak positive correlation with normalized time to maximal humerus velocity (r = .458, P = .04). Stride length had a moderate negative correlation with normalized time to maximal thorax velocity (r = −.522, P = .02) and dominant hip total rotational motion (TRM; r = −.660, P = .002), and had a strong negative correlation with normalized time from stride foot contact to maximal knee flexion (r = −.722, P < .001). Dominant limb YBT-LQ composite score had a weak negative correlation with hip abduction strength difference (r = −.459, P = .04) and normalized time to maximal thorax velocity (r = −.468, P = .04). Nondominant limb YBT-LQ composite score demonstrated a weak negative correlation with normalized time to maximal thorax velocity (r = −.450, P = .05) and had a moderate negative correlation with dominant hip TRM (r = −.668, P = .001). There were no other significant relationships between the remaining variables. Conclusions: YBT-LQ is a clinical measure that can be used to correlate with hip musculoskeletal characteristics and pitching kinematics in NCAA Division I pitchers.

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Kurt Manal, Justin D. Cowder and Thomas S. Buchanan

In this article, we outline a method for computing Achilles tendon moment arm. The moment arm is computed from data collected using two reliable measurement instruments: ultrasound and video-based motion capture. Ultrasound is used to measure the perpendicular distance from the surface of the skin to the midline of the tendon. Motion capture is used to determine the perpendicular distance from the bottom of the probe to the ankle joint center. The difference between these two measures is the Achilles tendon moment arm. Unlike other methods, which require an angular change in joint position to approximate the moment arm, the hybrid method can be used to compute the moment arm directly at a specific joint angle. As a result, the hybrid method involves fewer error-prone measurements and the moment arm can be computed at the limits of the joint range of motion. The method is easy to implement and uses modalities that are less costly and more accessible than MRI. Preliminary testing using a lamb shank as a surrogate for a human ankle revealed good accuracy (3.3% error). We believe the hybrid method outlined here can be used to measure subject-specific moment arms in vivo and thus will potentially benefit research projects investigating ankle mechanics.

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David R. Mullineaux, Hilary M. Clayton and Lauren M. Gnagey

This study assessed the effect of offset normalizations on variability in kinematic data. The tarsal angles for 12 elderly horses, with mild lameness of the tarsal joint, were measured at the trot pre and post 2 weeks administration of a dietary supplement intended to promote joint health (Corta-Flx, Nature's Own, Aiken, SC). For five strides, pre- and postsupplement, the tarsal angles measured on the flexor side (full exten. = 180°) were smoothed, normalized to 101 data points, and averaged. Four offset normalizations were applied: minus standing tarsal angle (Tarsal); minus impact angle (Impact); minus mean angle (Average); multiplicative scatter correction (MSC). For 11 angle variables across the stride there were no significant differences pre- and postsupplement, p > 0.05. Normalization had no effect on the timing of variables or magnitude of angles, but generally the variability in the angles was reduced. Least to greatest reduction occurred with the Tarsal, Impact, Average, then MSC normalizations. The Average and MSC techniques resulted in two and three variables, respectively, becoming significantly different. These differences were small, emphasizing that significant findings should be interpreted for meaningfulness. Normalizations based on the data gave the largest reductions in variability, but these may introduce biases into the data. Thus, normalization with respect to measurements external to data capture may be preferable, but their theoretical and statistical relationship to the kinematic variables should be confirmed. MSC altered the shape of the kinematic trace, which may be misleading. Offset normalizations should be used with care, but they can reduce variability in kinematic data to increase statistical power in biomechanical studies.

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Christopher Melton, David R. Mullineaux, Carl G. Mattacola, Scott D. Mair and Tim L. Uhl

Context:

Dynamic shoulder motion can be captured using video capture systems, but reliability has not yet been established.

Objective:

To compare the reliability of 2 systems in measuring dynamic shoulder kinematics during forward-elevation movements and to determine differences in these kinematics between healthy and injured subjects.

Design:

Reliability and cohort.

Setting:

Research laboratory.

Participants:

11 healthy subjects and 10 post–superior labrum anteroposterior lesion patients (SLAP).

Intervention:

Contrasting markers were placed at the hip, elbow, and shoulder to represent shoulder elevation and were videotaped in 2 dimensions. Subjects performed 6 repetitions of active elevation (AE) and active assisted elevation of the shoulder, and 3 trials were analyzed using Datapac (comprehensive system) and Dartfish (basic system).

Main Outcome Measures:

Amplitudes and velocities of the shoulder angle were calculated. Intraclass correlation coefficient (ICC), standard error of measurement (SEM), and levels of agreement (LOA) were used to determine intersystem and intertrial reliability.

Results:

For AE, the amplitude maximum (ICC = .98–.99, SEM = 2–3°, LOA = −9° to 5°) and average velocity (ICC = .94–.97, SEM = 1°/s, LOA = −4° to 1°/s) indicated excellent intersystem reliability between systems. Intratrial reliability for minimum velocity was moderate for Datapac (ICC = .64, SEM = 4°/s, LOA = 7°/s) and poor for Dartfish (ICC = .52, SEM = 20°/s, LOA = 37°/s). Cohort results demonstrated for AE a greater amplitude for healthy v SLAP (139° ± 11° v 113° ± 13°; P = .001) and interaction for an average velocity increase of 2°/s in healthy and decrease of 2°/s in SLAP patients over the 3 trials (P = .02).

Conclusions:

Reliability ranges provide the means to assess the clinical meaningfulness of results. The cohort differences are supported when the values exceed the ranges of the SEM; hence the amplitude results are meaningful. For dynamic shoulder elevation measured using video, the assessment of velocity was found to produce moderate to good reliability. The results suggest that with these measures subtle changes in both measures may be possible with further investigations.

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Martin Watson, Daniele Bibbo, Charles R. Duffy, Philip E. Riches, Silvia Conforto and Andrea Macaluso

In a laboratory setting where both a mechanically-braked cycling ergometer and a motion analysis (MA) system are available, flywheel angular displacement can be estimated by using MA. The purpose of this investigation was to assess the validity and reliability of a MA method for measuring maximal power output (Pmax) in comparison with a force transducer (FT) method. Eight males and eight females undertook three identical sessions, separated by 4 to 6 days; the first being a familiarization session. Individuals performed three 6-second sprints against 50% of the maximal resistance to complete two pedal revolutions with a 3-minute rest between trials. Power was determined independently using both MA and FT analyses. Validity: MA recorded significantly higher Pmax than FT (P < .05). Bland–Altman plots showed that there was a systematic bias in the difference between the measures of the two systems. This difference increased as power increased. Repeatability: Intraclass correlation coefficients were on average 0.90 ± 0.05 in males and 0.85 ± 0.08 in females. Measuring Pmax by MA, therefore, is as appropriate for use in exercise physiology research as Pmax measured by FT, provided that a bias between these measurements methods is allowed for.

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Daniel J. Brinkmann, Harald Koerger, Albert Gollhofer and Dominic Gehring

volume. A 12-camera motion analysis system (Vicon Motion Systems) was used to capture lower-limb kinematic data with a sampling frequency of 200 Hz. A standard full-body marker set was used with 37 retroreflective markers (diameter: 14 mm) that were attached to anatomical landmarks (torso, pelvis, and

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Matthew D. Milewski, Sylvia Õunpuu, Matthew Solomito, Melany Westwell and Carl W. Nissen

Documentation of the lower extremity motion patterns of adolescent pitchers is an important part of understanding the pitching motion and the implication of lower extremity technique on upper extremity loads, injury and performance. The purpose of this study was to take the initial step in this process by documenting the biomechanics of the lower extremities during the pitching cycle in adolescent pitchers and to compare these findings with the published data for older pitchers. Three-dimensional motion analysis using a comprehensive lower extremity model was used to evaluate the fast ball pitch technique in adolescent pitchers. Thirty-two pitchers with a mean age of 12.4 years (range 10.5–14.7 years) and at least 2 years of experience were included in this study. The pitchers showed a mean of 49 ± 12° of knee flexion of the lead leg at foot contact. They tended to maintain this position through ball release, and then extended their knee during the follow through phase (ball release to maximal internal glenohumeral rotation). The lead leg hip rapidly progressed into adduction and flexion during the arm cocking phase with a range of motion of 40 ± 10° adduction and 30 ± 13° flexion. The lead hip mean peak adduction velocity was 434 ± 83°/s and flexion velocity was 456 ± 156°/s. Simultaneously, the trailing leg hip rapidly extended approaching to a mean peak extension of –8 ± 5° at 39% of the pitch cycle, which is close to passive range of motion constraints. Peak hip abduction of the trailing leg at foot contact was –31 ± 12°, which also approached passive range of motion constraints. Differences and similarities were also noted between the adolescent lower extremity kinematics and adult pitchers; however, a more comprehensive analysis using similar methods is needed for a complete comparison.

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Daniel W.T. Wundersitz, Paul B. Gastin, Samuel J. Robertson and Kevin J. Netto

Context:

Accelerometer peak impact accelerations are being used to measure player physical demands in contact sports. However, their accuracy to do so has not been ascertained.

Purpose:

To compare peak-impact-acceleration data from an accelerometer contained in a wearable tracking device with a 3-dimensional motion-analysis (MA) system during tackling and bumping.

Methods:

Twenty-five semielite rugby athletes wore a tracking device containing a 100-Hz triaxial accelerometer (MinimaxX S4, Catapult Innovations, Australia). A single retroreflective marker was attached to the device, with its position recorded by a 12-camera MA system during 3 physical-collision tasks (tackle bag, bump pad, and tackle drill; N = 625). The accuracy, effect size, agreement, precision, and relative errors for each comparison were obtained as measures of accelerometer validity.

Results:

Physical-collision peak impact accelerations recorded by the accelerometer overestimated (mean bias 0.60 g) those recorded by the MA system (P < .01). Filtering the raw data at a 20-Hz cutoff improved the accelerometer’s relationship with MA data (mean bias 0.01 g; P > .05). When considering the data in 9 magnitude bands, the strongest relationship with the MA system was found in the 3.0-g or less band, and the precision of the accelerometer tended to reduce as the magnitude of impact acceleration increased. Of the 3 movements performed, the tackle-bag task displayed the greatest validity with MA.

Conclusions:

The findings indicate that the MinimaxX S4 accelerometer can accurately measure physical-collision peak impact accelerations when data are filtered at a 20-Hz cutoff frequency. As a result, accelerometers may be useful to measure physical collisions in contact sports.

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Aaron T. Scanlan, Ben J. Dascombe, Andrew P. Kidcaff, Jessica L. Peucker and Vincent J. Dalbo

Purpose:

To compare game activity demands between female and male semiprofessional basketball players.

Methods:

Female (n = 12) and male (n = 12) semiprofessional basketball players were monitored across 3 competitive games. Time–motion-analysis procedures quantified player activity into predefined movement categories across backcourt (BC) and frontcourt (FC) positions. Activity frequencies, durations, and distances were calculated relative to live playing time (min). Work:rest ratios were also calculated using the video data. Game activity was compared between genders for each playing position and all players.

Results:

Female players performed at greater running work-rates than male players (45.7 ± 1.4 vs. 42.1 ± 1.7 m/min, P = .05), while male players performed more dribbling than female players (2.5 ± 0.3 vs. 3.0 ± 0.2 s/min; 8.4 ± 0.3 vs. 9.7 ± 0.7 m/min, P = .05). Positional analyses revealed that female BC players performed more low-intensity shuffling (P = .04) and jumping (P = .05), as well as longer (P = .04) jogging durations, than male BC players. Female FC players executed more upper-body activity (P = .03) and larger work:rest ratios (P < .001) than male FC players. No significant gender differences were observed in the overall intermittent demands, distance traveled, high-intensity shuffling activity, and sprinting requirements during game play.

Conclusions:

These findings indicate that gender-specific running and dribbling differences might exist in semiprofessional basketball. Furthermore, position-specific variations between female and male basketball players should be considered. These data may prove useful in the development of gender-specific conditioning plans relative to playing position in basketball.