Exploring the use of wireless inertial measurement units for biomechanical analysis of side-step cutting manoeuvres

Exploring the use of wireless inertial measurement units for biomechanical analysis of side-step cutting manoeuvres

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 s...

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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 display 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 ultrasonography. 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 previously 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 intensities. 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 asymmetry 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 function, or potential contribution to pathology. Walking and running are among the most common recreational physical activities performed 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 generate 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 amplitude 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 during running was similar to that of other posterior thigh muscles reported in the literature, such as the hamstring. The QF may therefore 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 populations 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 examine 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 vertical 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 examined. 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 conditions. 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

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

examined for their ability to provide insight into side-step-cutting performance. Results: Variations were seen between thigh and shank angular velocity variables between cutting conditions; and in the accelerations of body segments from individual cutting performances, particularly at the trunk and sacrum. Examination of IMU-derived sagittal plane hip and knee joint angles revealed similar temporal patterns and values to previous research examining comparable side-step cutting motions. Discussion: Metrics derived directly from IMU outputs appeared sensitive to different movement patterns, and therefore may be useful for identifying high- versus low-risk side-step cutting performances. While IMUs can provide estimates of joint angles during a cutting manoeuvre, these are yet to be assessed for accuracy, and certain limitations surrounding how these are derived may restrict their use in practical situations. Future work should focus on linking these IMU-derived metrics to known injury risk factors to enhance our understanding of how IMUs can be used to analyse side-step cutting manoeuvres in field environments. http://dx.doi.org/10.1016/j.jsams.2014.11.149 24 Neighborhood social environment, perceived safety and physical activity among women living in disadvantaged neighborhoods. A mediation analysis A. Timperio ∗ , J. Veitch, A. Carver Deakin University, Australia Background: The social environment within neighbourhoods may be an important influence women’s physical activity. However, the mechanisms by which the social environment may influence physical activity have not been explored. Although it is likely that social conditions influence feelings of safety, many studies include perceived safety within aggregate scores of the social environment. The purpose of this study is to examine associations between the neighbourhood social environment and leisure-time physical activity (LTPA) among women, and whether these associations are mediated by perceived personal safety. Methods: This paper is based on cross-sectional data from the READI study. Women (n = 3784) living in disadvantaged urban and rural neighborhoods completed a survey on social environment variables, perceived personal safety and their LTPA and walking behavior in a usual week. The IPAQ-L was used to assess LTPA and walking, both of which were dichotomized (<150 min/week vs ≥150 min/week). Social environment variables included items regarding violence, crime, seeing others walking or exercising and social trust/cohesions within the neighbourhood. Linear regression analyses examined associations between the social environment and physical activity. Potential mediating pathways were assessed using MacKinnon’s product-of-coefficients test. Results: All social environment variables were positively associated with engaging in at least 150 min/week of LTPA. A perceived lack of violence (OR = 1.16), safety from crime (OR = 1.18), seeing others walking (OR = 1.38) and exercising (OR = 1.56) and social trust/cohesion score (OR = 1.28) were associated with higher odds of sufficient LTPA. Perceived personal safety mediated each of these associations (ab-paths were statistically significant). Results were less consistent for walking ≥150 min/week; only seeing other people walking (OR = 1.45) and exercising (OR = 1.31) were significantly associated with walking. However, perceived personal safety

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mediated associations with walking for each social environment variable (ab-paths were statistically significant). Discussion: This study has shown that perceived crime, violence, social norms for physical activity and social trust/cohesion influence women’s feelings of safety, which in turn is associated with less LTPA and walking. Perceived personal safety is a separate construct though which social conditions operate, and should not be included in composite or aggregate scores relating to the social conditions. http://dx.doi.org/10.1016/j.jsams.2014.11.150 25 Activating a whole community. Beat the Street W. Bird Intelligent Health, Australia It has been suggested that walking is ‘the perfect exercise’. It is accessible to nearly everyone, free of cost, low impact and low risk. Studies have shown it to be effective in reducing the risk of many chronic illnesses from cardiovascular disease to depression. Physical activity projects aimed at improving health are typically targeted at segments of a community. Beat the Street is a walking project that activated a whole community using the latest innovation in walking technology – the ‘walk tracking unit’ or ‘beat box’ and RFID ‘smartcards’. This project builds on Intelligent Health’s Beat the Street Global School Walking Challenge which demonstrated a 20% increase in walking in students aged between 11 and 13 across four countries and 12 schools. Beat the Street Caversham however, involves the whole community and reached out to the 30,000 residents of Caversham, near Reading, UK, inviting them to take part in a competition to walk more and to help raise money for books for local schools. It was designed to meet the objectives of the UK Government’s Department of Transport Local Sustainable Transport Fund: reducing congestion, improving air quality and promoting economic growth while conveying health benefits associated with active travel and walking in particular. The project was promoted through schools, doctors’ surgeries, local business and community groups and local media. This pilot was designed as a feasibility project to ascertain how the technology could be used across a whole community and whether the concept engaged sufficient people to have an impact. The evaluation methodology consisted of analysing data generated by the RFID card swipes from individuals and an exit survey with a sample of 1300 adults, along with qualitative feedback from participants. Over three months from June to September 2013, 5651 people, of which 2627 were schoolchildren, took part in the project (approx. 20% of the population), collectively achieving an estimated total distance covered of 50,000 miles (or 80,000 kilometres). A total of 255,015 ‘valid journeys’ were logged. A ‘valid journey’ consisted of a swipe on two different beat boxes within an hour. Beat boxes were place approximately 0.3 of a mile apart. The main motivations reported by people for taking part included ‘having fun’ and ‘winning points’. In addition, people 67% reported walking more as a result of Beat the Street and 80% said they would continue with the changes they had made to the way they get around. The project is now being rolled out to the 180,000 residents of Reading, UK in May 2014, jointly funded by the Clinical Commissioning Group and local authority transport and public health teams. Similar projects are planned in six other cities in the UK