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Gretchen D. Oliver, Jessica K. Washington, Sarah S. Gascon, Hillary A. Plummer, Rafael F. Escamilla and James R. Andrews

in baseball pitchers, 7 – 9 softball pitchers, 10 softball position players, 11 as well as baseball and softball catchers have been reported. 12 The premise that efficient hip muscle activation through a stable pelvis allows for efficient transfer of energy through the kinetic chain warrant

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Leo Ng, Amity Campbell, Angus Burnett and Peter O’Sullivan

The trunk and pelvis kinematics of 20 healthy male and female adolescent rowers were recorded during an ergometer trial using an electromagnetic tracking system (Fastrak). The kinematics of each drive phase were collected during the 1st and 20th minute, respectively. The mean and range of the kinematics, stroke rate and stroke length were compared between genders and over time. Male rowers postured their pelvis with more posterior tilt and their thoracic spine in more flexion than female rowers (P < .05). Both genders postured their pelvis in more posterior pelvic rotation and upper trunk in more flexion over time. Male rowers were found to have a significantly shorter drive phase than female rowers (P = .001). Differences in trunk and pelvic kinematics between adolescent male and female rowers suggest potentially various mechanisms for biomechanical stress. Assessment and training of rowers should take gender differences into consideration.

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Loren Z.F. Chiu and George J. Salem

Sacral marker and pelvis reconstruction methods have been proposed to approximate total body center of mass during relatively low intensity gait and hopping tasks, but not during a maximum effort vertical jumping task. In this study, center of mass displacement was calculated using the pelvic kinematic method and compared with center of mass displacement using the ground-reaction force-impulse method, in experienced athletes (n = 13) performing restricted countermovement vertical jumps. Maximal vertical jumps were performed in a biomechanics laboratory, with data collected using an 8-camera motion analysis system and two force platforms. The pelvis center of mass was reconstructed from retro-reflective markers placed on the pelvis. Jump height was determined from the peak height of the pelvis center of mass minus the standing height. Strong linear relationships were observed between the pelvic kinematic and impulse methods (R 2 = .86; p < .01). The pelvic kinematic method underestimated jump height versus the impulse method, however, the difference was small (CV = 4.34%). This investigation demonstrates concurrent validity for the pelvic kinematic method to determine vertical jump height.

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Roland van den Tillaar and Gertjan Ettema

The aim of this study was to investigate the contribution of upper extremity, trunk, and lower extremity movements in overarm throwing in team handball. In total, 11 joint movements during the throw were analyzed. The analysis consists of maximal angles, angles at ball release, and maximal angular velocities of the joint movements and their timing during the throw. Only the elbow angle (extension movement range) and the level of internal rotation velocity of the shoulder at ball release showed a significant relationship with the throwing performance. Also, a significant correlation was found for the timing of the maximal pelvis angle with ball velocity, indicating that better throwers started to rotate their pelvis forward earlier during the throw. No other significant correlations were found, indicating that the role of the trunk and lower limb are of minor importance for team handball players.

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Dale Bickham, Warren Young and Peter Blanch

Objective:

To determine the relationship between lumbopelvic (LP) stabilization strength and pelvic motion during running.

Design:

Runners were assessed for pelvic motion and undertook an LP stabilization strength test.

Participants:

Sixteen elite male middle- and long-distance runners.

interventions:

Pelvis kinematics were assessed while subjects ran at 5 m/s on a treadmill.

Main Outcome Measures:

Angular pelvis displacement was divided into 3 axes of rotation: pelvic tilt, obliquity, and rotation. LP stabilization strength was the capacity to resist increasing static loads applied to each leg and maintain a neutral LP zone. Intercorrelations were calculated for all measures of pelvic motion and LP stabilization strength.

Results:

There were no significant relationships found among any of the variables (P > .05). However, the LP stabilization strength test possessed good interday reliability.

Conclusions:

The relationship between pelvic motion and muscle function should be studied under a variety of other conditions.

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Brendan M. Marshall, Andrew D. Franklyn-Miller, Kieran A. Moran, Enda A. King, Siobhán C. Strike and Éanna C Falvey

Context:

Chronic athletic groin pain (AGP) is common in field sports and has been associated with abnormal movement control and loading of the hip and pelvis during play. A single-leg squat (SLS) is commonly used by clinicians to assess movement control, but whether it can provide insight into control during more dynamic sporting movements in AGP patients is unclear.

Objective:

To determine the relationships between biomechanical measures in an SLS and the same measures in a single-leg drop landing, single-leg hurdle hop, and a cutting maneuver in AGP patients.

Design:

Cross-sectional study.

Setting:

Biomechanics laboratory.

Patients:

40 recreational field-sports players diagnosed with AGP.

Intervention:

A biomechanical analysis of each individual’s SLS, drop landing, hurdle hop, and cut was undertaken.

Main Outcome Measures:

Hip, knee, and pelvis angular displacement and hip and knee peak moments. Pearson product–moment correlations were used to examine relationships between SLS measures and equivalent measures in the other movements.

Results:

There were no significant correlations between any hip or pelvis measure in the SLS with the same measures in the drop landing, hurdle hop, or cut (r = .03–.43, P > .05). Knee frontal- and transverse-plane angular displacement were related in the SLS and drop landing only, while knee moments were related in the SLS, drop-landing, and hurdle hop (r = .50–.67, P < .05).

Conclusion:

For AGP patients, an SLS did not provide meaningful insight into hip and pelvis control or loading during sporting movements that are associated with injury development. The usefulness of an SLS test in the assessment of movement control and loading in AGP patients is thus limited. The SLS provided moderate insight into knee control while landing and therefore may be of use in the examination of knee-injury risk.

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Alan Barr and David Hawkins

An anatomical database was constructed containing three-dimensional geometric representations of the structures comprising the lower extremity. The database was constructed by digitizing 100 high-resolution digital photographic images supplied from the National Library of Medicine’s Visual Human Male (VHM) project. These images were taken of sequential transverse cross-sectional slices of the leg. Slices were located 1 cm apart between a location approximately 3 mm below the superior aspect of the ilium and approximately 2 mm below the distal end of the fibula. Image Tool Software (v. 2.0) was used to manually digitize the perimeters of muscles, tendons, and bones of the pelvis, thigh, and shank from the right leg of the VHM. Additionally, the perimeter of the leg and the inner aspect of the superficial fat layer were digitized. The pelvis was digitized as a hemi-pelvis. Tissue perimeters were characterized using between 10 and 151 nodes within each slice; the number of nodes varied depending on the tissue’s size. Transverse cross-sectional slice number, structure identification, node number, and the two-dimensional coordinates of each node were stored in a data file. The information contained in this file is unique and provides a database that researchers can use to investigate questions related to tissue anatomy and movement mechanics that cannot be considered using existing musculoskeletal data sets.

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Max C. Stuelcken, René E.D. Ferdinands and Peter J. Sinclair

This study aimed to investigate the bowling techniques of female fast bowlers and identify any association between a history of low back pain (LBP) and the movement patterns of the thorax relative to the pelvis during the delivery stride of the bowling action. Three-dimensional kinematic data were collected from 26 elite Australian female fast bowlers using an eight-camera Vicon motion analysis system. Nineteen bowlers used a mixed action, 6 bowlers used a semiopen action, and 1 bowler used a side-on action. Fourteen bowlers had a history of LBP. Eight of these 14 bowlers used a mixed action, and bowlers with more shoulder counterrotation were no more likely to have a history of LBP. Bowlers with a history of LBP positioned the thorax in more left lateral flexion relative to the pelvis between 73–79% of the delivery stride, and moved the thorax through a significantly greater range of lateral flexion relative to the pelvis during the delivery stride compared with bowlers with no history of LBP. This information will give coaches and support staff a better understanding of female bowling technique and may facilitate better screening practices for elite female cricketers.

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M. A. Urbin, David Stodden and Glenn Fleisig

Individual body segment actions evolve during throwing skill development. Maximal trunk involvement is typically the last feature of the movement pattern to fully develop. The current study examined developmental levels of trunk action and the associated variability in the throwing motion. The throwing motions of children and adolescents were analyzed via motion capture and trunk actions were classified as exhibiting no rotation (n = 7), blocked rotation (n = 6), or differentiated rotation (n = 11). Results indicated nonrotators exhibited greater variability than blocked-rotators in maximum humeral external rotation and humeral horizontal adduction angles at ball release; nonrotators also demonstrated greater variability than differentiated-rotators on these parameters, in addition to forward trunk tilt and elbow extension angle at ball release. Nonrotators produced more variable peak upper torso and humeral horizontal adduction angular velocities, as well as peak upper torso linear velocity, relative to differentiated-rotators. Blocked-rotators produced more variable peak pelvis, upper torso, and humeral horizontal adduction angular velocities, as well peak pelvis linear velocity, relative to differentiated-rotators. Nonrotators were less consistent relative to blocked- and differentiated-rotators in the time that elapsed from peak pelvis angular velocity to ball release. These results indicate that greater trunk involvement is associated with more consistent movement production.

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Rafael F. Escamilla, Glenn S. Fleisig, Coop DeRenne, Marcus K. Taylor, Claude T. Moorman III, Rodney Imamura, Edward Barakatt and James R. Andrews

A motion system collected 120-Hz data from 14 baseball adult hitters using normal and choke-up bat grips. Six swings were digitized for each hitter, and temporal and kinematic parameters were calculated. Compared with a normal grip, the choke-up grip resulted in 1) less time during stride phase and swing; 2) the upper torso more opened at lead foot contact; 3) the pelvis more closed and less bat linear velocity at bat-ball contact; 4) less range of motion of the upper torso and pelvis during swing; 5) greater elbow flexion at lead foot contact; and 6) greater peak right elbow extension angular velocity. The decreased time during the stride phase when using a choke-up grip implies that hitters quicken their stride when they choke up. Less swing time duration and less upper torso and pelvis rotation range of motion using the choke-up grip supports the belief of many coaches and players that using a choke-up grip results in a “quicker” swing. However, the belief that using a choke-up grip leads to a faster moving bat was not supported by the results of this study.