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 to determine if those with a history of strain injury in the BFlh dis- play differing architectural characteristics compared to uninjured limbs. Methods: Thirty six males were recruited in this case–control study (uninjured, recreationally active control group: mean age = 26.2, range 19.1–41.4 [n = 20] and elite athlete previously injured unilateral BFlh group: mean age = 23.7, range 18.5–31.5 [n = 16]). The BFlh architecture was assessed at rest and during graded isometric contractions using two-dimensional ultraso- nography. The control group was assessed during three visits, interspersed by 24 h, to determine reliability. Previously injured individuals were evaluated during a single testing session. Two tailed independent and dependent t-tests with an adjusted p value of 0.0125 because of Bonferroni corrections employed to account for inflated type I error due to multiple comparisons. Results: Two-dimensional ultrasonography is reliable for the assessment of BFlh architecture during all intensities (intraclass correlations [ICCs] = >0.90, typical error as a percentage co-efficient of variation [%TE] = < 5%). Absolute fascicle length, pennation angle and fascicle length relative to muscle thickness of the previ- ously injured BFlh were significantly different to the contralateral uninjured limb during all contraction intensities (p < 0.0125). The extent of the between limb asymmetry for relative fascicle length and 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 was significantly larger in previously injured participants compared to the control group at rest and 25% of maximum isometric voluntary contraction. Discussion: Two-dimensional ultrasonography is reliable for assessing BFlh architecture at rest and during graded isometric contractions. Fascicle length, pennation angle and fascicle length relative to muscle thickness are altered in previously injured BFlh compared to an uninjured contralateral BFlh. Previously injured participants 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 22 Quadratus femoris EMG function while running and walking in healthy adults A. Semciw ∗ , M. Freeman, B. Batten, T. Pizzari La Trobe University, Australia Introduction: Quadratus femoris (QF) is considered a key hip joint 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 running are among the most common recreational physical activities per- formed by Australians. These functional tasks have also been used clinically and in research to evaluate the contribution of muscles to joint stability, movement and pathology. The aim of this study was to provide the first account of QF muscle activity in healthy young adults while running and walking. This information will help to establish the functional significance of QF, and provide normative data for further evaluation in elite and pathological populations. Methods: Fine-wire EMG electrodes were inserted into the QF of nine 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 series of four running and walking trials at comfortable speed across a 10 m pathway. An EMG profile was generated from the middle two strides of each trial and averaged across all participants to gen- erate a grand ensemble curve across the gait cycle. These were amplitude normalized to per cent of maximum voluntary isometric contractions (MVICs), and time normalized to 100 points. The peak and average EMG amplitude was recorded within stance, swing, and overall stride during running and walking, and quantitatively compared 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 bursts during walking; however, both were in the stance phase. The ampli- tude of EMG activity in running was significantly higher than that of walking in all phases of the gait cycle, with the greatest differences present in the swing phase. Discussion: This was the first study to quantify the activity of QF within any population, during any task. The EMG profile dur- ing running was similar to that of other posterior thigh muscles reported in the literature, such as the hamstring. The QF may there- fore have a synergistic role with other posterior thigh muscles in running, by stabilising the hip joint in stance, and decelerating the limb 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 23 Exploring the use of wireless inertial measurement units for biomechanical analysis of 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, Deakin University, Australia 2 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 to laboratory settings. Wireless inertial measurement units (IMUs) provide a portable method for measuring the motion of major body segments and may offer a simplified method for the assessment of movement tasks in field environments. Metrics derived from IMUs have been linked to known injury risk factors during a drop verti- cal jump task, highlighting their potential for identifying high-risk movements. However, the sensitivity of IMUs in measuring more sport-specific tasks, such as side-step cutting, is yet to be exam- ined. Until this is understood, field-based application of IMUs is limited as it is unknown which IMU-based metrics may be useful for identifying high-risk movement strategies in sport-specific tasks. Therefore, the purpose of this study was to explore IMU-based metrics that advance the analysis of side-step cutting manoeuvres for 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 five 35–55 ◦ side-step cuts under anticipated and unanticipated condi- tions. Five wireless IMUs were placed on subjects at the trunk and sacrum, and thigh, shank and foot of the dominant limb. Raw IMU data were processed within custom MATLAB programs. Sagittal plane trunk, hip and knee, and frontal plane knee joint angles were calculated from IMU data. Acceleration and angular velocity data from segments was used to create a number of variables that were