Saturday 18 October Papers / Journal of Science and Medicine in Sport 18S (2014) e136–e162 e143

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Ipsilateral and contralateral corticospinalresponse to unilateral strength training aresimilar for both the dominant andnon-dominant limb

D. Kidgell

Deakin University, Australia

Introduction: It has been proposed that the cross-transfer ofstrength is greatest when motor training is completed by thedominant limb (in right handers only). The objective here wasto investigate the effect of limb dominance on the cross-transferof strength and corticospinal excitability and inhibition followingright or left limb unilateral strength training in right handed par-ticipants.

Methods: Twenty-two healthy right-handed males and femaleswere randomized into a control, right-hand training or left-handtraining group. All participants were tested for dynamic strength(1-RM) and muscle thickness. Transcranial magnetic stimulation(TMS) was used to assess corticospinal excitability and intracorti-cal inhibition of the contralateral and ipsilateral motor cortex. Thetraining groups competed 3 weeks of supervised wrist extensiontraining beginning at 70% of their 1-RM, for 4 sets of 6–8 repe-titions, which was externally paced (3 s concentric phase and 4 seccentric phase).

Results: Following unilateral resistance training, both groupsexhibited significant strength gain in the trained limb and theextent of the cross-transfer of strength was substantial and notdifferent between groups. TMS revealed that both groups dis-played bilateral increases in corticospinal excitability, indicatingthat unilateral training affects both the contralateral ‘trained’ andipsilateral ‘untrained’ motor cortices, independent of which limbis trained in strongly right handed individuals, but increasedcorticospinal excitability was not correlated with improved per-formance. Interestingly, intracortical inhibition was only reducedin the trained motor cortex; however, there were no differencesbetween groups following training.

Discussion: The present data does not provide evidence for therole of increased corticospinal excitability underpinning the cross-transfer of strength, however the magnitude of the cross-transferof strength is not limited by limb dominance; rather, it appearsto be dependent upon the motor control requirements of the taskprescribed.

http://dx.doi.org/10.1016/j.jsams.2014.11.145

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Lower extremity isokinetic muscle strength andjoint kinetics during landing tasks

M. Undheim 1,∗, S. Gore 1,2,3,A. Franklyn-Miller 1,4, E. King 1, M. Boland 1,E. Falvey 1

1 Sports Surgery Clinic, Australia2 School of Health and Human Performance, DublinCity University, Ireland3 Insight Centre for Data Analytics, Dublin CityUniversity, Ireland4 Centre for Health, Exercise and Sports Medicine,University of Melbourne, Australia

Background: Anterior cruciate ligament (ACL) injuries are oneof the most common knee injuries reported in pivotal sports.Following ACL reconstruction (ACLR), strength evaluation of the

quadriceps and hamstrings are frequently performed by cliniciansusing an isokinetic dynamometer (IKD). However, the IKD is criti-cized for its lack in functional relevance. Therefore, it is importantto investigate the relationship between IKD strength and biome-chanical variables of the lower limbs during sporting movementswhere ACL injuries are reported to occur, such as landing. The pur-pose of this study is to investigate the relationship between IKDstrength of the quadriceps and hamstrings and lower limb jointkinetics during landing from a single leg drop landing (SLDL) and ahurdle hop (HH).

Methods: 15 recreational field sports players, on average 6months post unilateral patellar tendon graft ACLR, volunteered totake part in this study (mean ± SD: post-ACLR: 27 ± 10.5 weeks;age: 25 ± 5.8 years; height: 180.3 ± 8.1 cm; mass: 85.3 ± 10.5 kg). A3D biomechanical analysis of the landing phases of the SLDL andHH were collected at 200 Hz using 8 Vicon Bonita cameras and 2AMTI force plates (BP400600). Concentric knee extension and flex-ion was analysed at an angular velocity of 60∞/s using a CybexNorm IKD. Pearson’s product moment correlations were carriedout between the IKD strength measures (peak torque normalisedto %body weight) and the biomechanical variables of landing ofthe injured leg (peak negative power and vGRF). An alpha level ofp < 0.05 was adopted for significance.

Results: For SLDL, peak negative knee power was significantlypositively correlated (p < 0.05) to H/Q ratio (r = 0.53) and hamstringstrength (r = 0.55). There were no other significant correlations,and no significant correlations were found between biomechanicallanding variables and isokinetic strength during HH.

Discussion: The results indicate that as the H/Q ratio and ham-string peak torque increases, the eccentric work decreases duringthe SLDL. However, this finding was only found in SLDL. There wereno other significant correlations found between IKD strength andlanding biomechanics. Therefore, it cannot be assumed that theisokinetic strength measures are related to functional landing per-formance. The lack in significant correlations, agree with resultsreported in previous research. Significant correlations betweenIKD strength and landing biomechanics have previously onlybeen reported in female participants. In this study both malesand females volunteered and were not separately analysed. Thiscould have affected the results. Further investigation is neededto improve and develop assessment and return to sport criteriafollowing ACLR.

http://dx.doi.org/10.1016/j.jsams.2014.11.146

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Differences exist in the architecturalcharacteristics of the biceps femoris long headin previously injured individuals

R. Timmins 1,∗, A. Shield 2, M. Williams 3,C. Lorenzen 1, D. Opar 1

1 Australian Catholic University, Australia2 Queensland University of Technology, Australia3 University of South Wales, Australia

Introduction: Hamstring strain injuries are the most commoninjury type in many running based sports. An as yet unresolvedissue with hamstring strain injury is the elevated risk of recur-rence, with reinjury rates ranging from 12 to 43%. Lesser fasciclelengths following hamstring strain injury might be troublesome forreinjury, as it would likely increase muscle susceptibility to eccen-trically induced microscopic muscle damage, increasing the risk ofmacroscopic damage. However, it is not yet known if a previouslystrained biceps femoris long head (BFlh) displays shorter fascicles

e144 Saturday 18 October Papers / Journal of Science and Medicine in Sport 18S (2014) e136–e162

compared to an uninjured BFlh. The purpose of this study was todetermine if those with a history of strain injury in the BFlh dis-play differing architectural characteristics compared to uninjuredlimbs.

Methods: Thirty six males were recruited in this case–controlstudy (uninjured, recreationally active control group: meanage = 26.2, range 19.1–41.4 [n = 20] and elite athlete previouslyinjured unilateral BFlh group: mean age = 23.7, range 18.5–31.5[n = 16]). The BFlh architecture was assessed at rest and duringgraded isometric contractions using two-dimensional ultraso-nography. The control group was assessed during three visits,interspersed by 24 h, to determine reliability. Previously injuredindividuals were evaluated during a single testing session. Twotailed independent and dependent t-tests with an adjusted p valueof 0.0125 because of Bonferroni corrections employed to accountfor inflated type I error due to multiple comparisons.

Results: Two-dimensional ultrasonography is reliable for theassessment of BFlh architecture during all intensities (intraclasscorrelations [ICCs] = >0.90, typical error as a percentage co-efficientof variation [%TE] = < 5%). Absolute fascicle length, pennation angleand fascicle length relative to muscle thickness of the previ-ously injured BFlh were significantly different to the contralateraluninjured limb during all contraction intensities (p < 0.0125). Theextent of the between limb asymmetry for relative fascicle lengthand pennation angle in the injured group was significantly larger(p < 0.0125) compared to the control group at all contraction inten-sities. Between limb asymmetry in absolute fascicle length wassignificantly larger in previously injured participants compared tothe control group at rest and 25% of maximum isometric voluntarycontraction.

Discussion: Two-dimensional ultrasonography is reliable forassessing BFlh architecture at rest and during graded isometriccontractions. Fascicle length, pennation angle and fascicle lengthrelative to muscle thickness are altered in previously injured BFlhcompared to an uninjured contralateral BFlh. Previously injuredparticipants display a significantly greater between limb asymme-try of the BFlh architecture than a control group.

http://dx.doi.org/10.1016/j.jsams.2014.11.147

Award finalist

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Quadratus femoris EMG function while runningand walking in healthy adults

A. Semciw ∗, M. Freeman, B. Batten, T. Pizzari

La Trobe University, Australia

Introduction: Quadratus femoris (QF) is considered a key hipjoint stabiliser. Surprisingly, there is no electromyography (EMG)based study that has verified its role in healthy lower limb func-tion, or potential contribution to pathology. Walking and runningare among the most common recreational physical activities per-formed by Australians. These functional tasks have also been usedclinically and in research to evaluate the contribution of muscles tojoint stability, movement and pathology. The aim of this study wasto provide the first account of QF muscle activity in healthy youngadults while running and walking. This information will help toestablish the functional significance of QF, and provide normativedata for further evaluation in elite and pathological populations.

Methods: Fine-wire EMG electrodes were inserted into the QF ofnine healthy young adults (mean age (range) = 23.7 (22–26) years;females = 4) who were active in at least two hours of running related

sport per week. The activity of QF was recorded during a seriesof four running and walking trials at comfortable speed across a10 m pathway. An EMG profile was generated from the middle twostrides of each trial and averaged across all participants to gen-erate a grand ensemble curve across the gait cycle. These wereamplitude normalized to per cent of maximum voluntary isometriccontractions (MVICs), and time normalized to 100 points. The peakand average EMG amplitude was recorded within stance, swing,and overall stride during running and walking, and quantitativelycompared using paired samples t-tests (˛ = 0.05).

Results: There were two bursts of EMG activity during running;one in stance and the other in late swing. There were also two burstsduring walking; however, both were in the stance phase. The ampli-tude of EMG activity in running was significantly higher than that ofwalking in all phases of the gait cycle, with the greatest differencespresent in the swing phase.

Discussion: This was the first study to quantify the activity ofQF within any population, during any task. The EMG profile dur-ing running was similar to that of other posterior thigh musclesreported in the literature, such as the hamstring. The QF may there-fore have a synergistic role with other posterior thigh muscles inrunning, by stabilising the hip joint in stance, and decelerating thelimb in late swing. Further work in elite and pathological popula-tions will improve our knowledge of this theoretically important,but understudied muscle.

http://dx.doi.org/10.1016/j.jsams.2014.11.148

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Exploring the use of wireless inertialmeasurement units for biomechanical analysisof side-step cutting manoeuvres

A. Fox 1,2,∗, S. Davidson 2, R. McGinnis 2, S. Cain 2,N. Saunders 1, S. McLean 2

1 School of Exercise and Nutrition Sciences, DeakinUniversity, Australia2 Human Performance Innovation Laboratory,University of Michigan, United States

Introduction: Current technologies that are often used to exam-ine the mechanics of sporting movements are often limited tolaboratory settings. Wireless inertial measurement units (IMUs)provide a portable method for measuring the motion of major bodysegments and may offer a simplified method for the assessment ofmovement tasks in field environments. Metrics derived from IMUshave been linked to known injury risk factors during a drop verti-cal jump task, highlighting their potential for identifying high-riskmovements. However, the sensitivity of IMUs in measuring moresport-specific tasks, such as side-step cutting, is yet to be exam-ined. Until this is understood, field-based application of IMUs islimited as it is unknown which IMU-based metrics may be useful foridentifying high-risk movement strategies in sport-specific tasks.Therefore, the purpose of this study was to explore IMU-basedmetrics that advance the analysis of side-step cutting manoeuvresfor future field-based research.

Methods: Seven male subjects (age = 21.3 ± 1.8 years;height = 179.2 ± 6.7 cm; weight = 75.0 ± 10.9 kg) performed five35–55◦ side-step cuts under anticipated and unanticipated condi-tions. Five wireless IMUs were placed on subjects at the trunk andsacrum, and thigh, shank and foot of the dominant limb. Raw IMUdata were processed within custom MATLAB programs. Sagittalplane trunk, hip and knee, and frontal plane knee joint angles werecalculated from IMU data. Acceleration and angular velocity datafrom segments was used to create a number of variables that were