Using stiffness to assess injury risk:comparison of methods for quantifying stiffness and their reliability in triathletes

Background: A review of the literature has indicated that lower body stiffness, defined as the extent to which the lower extremity joints resists deformation upon contact with the ground, may be a useful measure for assessing Achilles injury risk in triathletes. The nature of overuse injuries suggests that a variety of different movement patterns could conceivably contribute to the final injury outcome, any number and combination of which might be observed in a single individual. Measurements which incorporate both kinetics and kinematics (such as stiffness) of a movement may be better able to shed light on individuals at risk of injury, with further analysis then providing the exact mechanism of injury for the individual. Stiffness can be measured as vertical, leg or joint stiffness to model how the individual interacts with the environment upon landing. However, several issues with stiffness assessments limit the effectiveness of these measures to monitor athletes’ performance and/or injury risk. This may reflect the variety of common biomechanical stiffness calculations (dynamic, time, true leg and joint) that have been used to examine these three stiffness levels (vertical, leg and joint) across a variety of human movements (i.e. running or hopping) as well as potential issues with the reliability of these measures, especially joint stiffness. Therefore, the aims of this study were to provide a comparison of the various methods for measuring stiffness during two forms of human bouncing locomotion (running and hopping) along with the measurement reliability to determine the best methods to assess links with injury risk in triathletes. Methods: Vertical, leg and joint stiffness were estimated in 12 healthy male competitive triathletes on two occasions, 7 days apart, using both running at 5.0 ms−1 and hopping (2.2 Hz) tasks. Results: Inter-day reliability was good for vertical (ICC = 0.85) and leg (ICC = 0.98) stiffness using the time method. Joint stiffness reliability was poor when assessed individually. Reliability was improved when taken as the sum of the hip, knee and ankle (ICC = 0.86). The knee and ankle combination provided the best correlation with leg stiffness during running (Pearson’s Correlation = 0.82). Discussion: The dynamic and time methods of calculating leg stiffness had better reliability than the “true” method. The time and dynamic methods had the best correlation with the different combinations of joint stiffness, which suggests that they should be considered for biomechanical screening of triathletes. The knee and ankle combination had the best correlation with leg stiffness and is therefore proposed to provide the most information regarding lower limb mechanics during gait in triathletes

CHANGES IN LOWER EXTREMITY STIFFNESS WITH TRIATHLON SPECIFIC TRAINING

Achilles tendon injuries are problematic for triathletes ranked as the most severe injuries in club and development athletes. As an overuse injury, Achilles tendon injures were proposed to be the result of a combination of risk factors, requiring measurements which incorporated multiple risk factors. Stiffness was identified to be a measure that was influenced by many of the risk factors for Achilles injury. In a one-year prospective study, 75 triathletes were followed to determine the association between measures of lower extremity stiffness and the risk of developing an Achilles injury. Triathletes who developed a new or reoccurring injury during the surveillance period had higher leg and knee to ankle stiffness ratio compared to Uninjured athletes. The influence of transitioning from cycling to running, on lower extremity stiffness were assessed. Transitioning from cycling caused an increase in ankle stiffness (ES=0.55) but a decrease in knee stiffness (ES=-0.38). Individual responses are likely to be important when assessing injury risk

ISBS 2018 AUCKLAND CONFERENCE SPRINZ SPORT AND EXERCISE BIOMECHANICS TEACHING ARCHIVE PROGRAMME

The host of the archive is the J.E. Lindsay Carter Kinanthropometry Clinic and Archive (JELCKCA) at the Auckland University of Technology. The director of the Archive is Professor Patria Hume (AUT SPRINZ) and archive web master is Dr Anna Lorimer (Bond University and AUT SPRINZ). Initiation of this project was a result of planning and hosting the 36th Annual Conference of the International Society of Biomechanics in Sports (ISBS) in Auckland, New Zealand September 10-14, 2018. This archive is a place to share (upload) and obtain (download) electronic image files that are intended for non-profit instructional use in sport and exercise biomechanics classes and educational outreach programs (e.g. National Biomechanics Day). Archive images are indented to be stand-alone instructional slides or can be photo/images/graphics that illustrate biomechanical data, principles, theories, or application. While human sport and exercise examples are preferred, any animal biomechanical images of potential interest and instructional value are welcome. Images in the archive are organized into the following thirteen categories to facilitate user access: Active Learning Experiences, Applications in Professions, Core Concepts, Data Collection, Demonstrations, EMG/Neuromuscular, Fluids, Kinematics, Kinetics, Muscle Mechanics, Theories, Videos, and Other. Downloading and Use Expectations: Users of image-slides from this archive are expected to not alter the image to exclude the references to the original data, image, or image author(s) at the bottom of each image. These image-slides are for non-profit, educational use with universities, schools, conferences, or other service presentations. They are not intended for use in consulting for personal profit. All materials in this archive are intended for free, fair educational use, so any material (images, video, content) that has explicit for-profit copyright, trademark, or other legal limitations on educational use should NOT be uploaded. Uploading Expectations: Please upload only standard, widely supported electronic image (.jpg, .png or .gif) or short, compressed video files (.avi, .gif., .mov, .mpeg). Please strive to use a wide, horizontal layout common in MS PowerPoint slides (vertical to horizontal ratio of 1:1.9). Sources of all published data should be cited in APA format (Author, year). ALL slides should also identify the person submitting the slice on the bottom, lower left. We recommend the following format for this acknowledgement: Slide by First Initial. Slide Author Surname for educational use only. All uploads require the entry of the name and email address of the person that created the submission, along with a few suggestions describing the potential use of the image-slide. Please use a filename that is descriptive of the image-slide content (e.g., MuscleActions.jpg). All content to be uploaded will be reviewed by the Archive managers before it is made publically available

Physical activity, sedentary behavior, and depressive symptoms among adolescents

BACKGROUND: This study examined cross-sectional and longitudinal associations between physical activity, sedentary behavior, and depressive symptoms among adolescents. METHODS: Participants were 155 adolescents (14.4 years±0.61) in 2004 (40% boys). Data collection occurred in 2004 and again in 2006. At both time points, participants completed the Centers for Epidemiological Studies Depression Scale for Children (CES-DC), from which they were classified as having depressive symptoms (≥15) or not (<15). Organized sport and TV viewing were self-reported and moderate-to-vigorous (MVPA) and vigorous (VPA) physical activity and sedentary time were objectively measured. Logistic and linear regression analyses examined cross-sectional and longitudinal associations between MVPA, VPA, organized sport, TV viewing, sedentary time, and symptoms of depression. RESULTS: There were no cross-sectional or longitudinal associations between MVPA, VPA, organized sport, sedentary time, and symptoms of depression among boys or girls. However, having symptoms of depression in 2004 did predict higher TV viewing among adolescent girls in 2006 (approximately 168 minutes/week more TV viewing; P≤.001). CONCLUSIONS: MVPA, VPA, organized sport and objectively-measured sedentary time appeared unrelated to depressive symptoms in this sample, but depressive symptoms predicted increased TV viewing over time among adolescent girls. Further research is required to determine the clinical relevance of this finding.Clare Hume, Anna Timperio, Jenny Veitch, Jo Salmon, David Crawford, and Kylie Bal

Are independent mobility and territorial range associated with park visitation among youth?

BACKGROUND: Parks are important for providing opportunities for physical activity among youth. Apart from engaging in physical activity whilst visiting a park, active transportation (e.g. walking or cycling) to parks is potentially an additional source of physical activity. Previous research has shown that a major barrier to young people visiting parks is their inability to visit parks unaccompanied by an adult. It is not known; however, whether young people who have greater independent mobility and territorial range (ability to move around their neighbourhood alone or with friends, unaccompanied by an adult) are more likely to visit parks. This study examined park visitation and travel mode to parks and whether independent mobility and territorial range were associated with park visitation among youth living in disadvantaged areas of Victoria, Australia. METHODS: In 2010-11, 311 youth aged 8-16 years self-reported their park use, active transport, independent mobility to parks, and territorial range. Logistic regression models determined the odds of park visitation (once per week or more) according to independent mobility and territorial range, adjusting for key covariates. RESULTS: Overall, 75% of participants reported visiting parks, and 37% visited their 'usual' park at least once per week. Of those who reported visiting parks, 87% travelled to the park they usually visited using active transport: 57% walked, 22% cycled, and 8% used a scooter/skateboard. Just 15% and 13% of youth regularly walked or cycled alone to parks/playgrounds respectively, and 25% and 19% regularly walked or cycled with friends or siblings (no adults) respectively. For the 84% who reported having parks/playgrounds within walking distance from home, those who regularly walked alone to parks (OR 3.61; CI=1.67, 7.80), and regularly walked (OR 2.27; CI=1.14, 4.55) or cycled (OR 3.38; CI=1.73, 6.62) with friends to parks, were significantly more likely to visit a park at least once per week, compared to others. CONCLUSIONS: This study showed that active transport is frequently used by this sample of young people to travel to parks. Findings also highlight the potential importance of providing opportunities for youth aged 8-16 years to visit local parks independent of an adult.Jenny Veitch, Alison Carver, Clare Hume, David Crawford, Anna Timperio, Kylie Ball and Jo Salmo

Parent\u27s views of the importance of making changes in settings where children spend time to prevent obesity

Aim : To examine the kinds of changes parents would like to see in those settings where children spend time (kindergartens and schools, child care centres and after-school care facilities, and the local neighbourhood) in policies and practices that impact on children&rsquo;s risk of obesity, and to establish whether parents might be willing to advocate for changes in these settings. Materials and Methods : 175 parents from five randomly selected primary schools and five randomly selected kindergartens located in suburbs of metropolitan Melbourne completed a questionnaire in which they rated the importance of a number of potential changes to promote healthy eating and increase physical activity in their children. Results : Parents of children in kindergarten most commonly rated changes to the eating environment as important. In contrast, parents of primary school children believed changes related to both eating and physical activity in school were important. Ninety-five per cent of parents of kindergarten children and 89% of parents of primary school children believed it was possible for parents to bring about change to provide more opportunities for their child to eat more healthily and be more physically active. One in four parents reported that they had thought about or had tried to bring about changes in their community. Conclusions : The findings suggest that mobilising parents to take an active role in advocating for change in those settings that have the potential to shape their children&rsquo;s physical activity and eating behaviours may be feasible.<br /

Csf1r-mApple transgene expression and ligand binding in vivo reveal dynamics of CSF1R expression within the mononuclear phagocyte system

CSF1 is the primary growth factor controlling macrophage numbers, but whether expression of the CSF1 receptor differs between discrete populations of mononuclear phagocytes remains unclear. We have generated a Csf1r-mApple transgenic fluorescent reporter mouse that, in combination with lineage tracing, Alexa Fluor 647-labeled CSF1-Fc and CSF1, and a modified Delta Csf1-enhanced cyan fluorescent protein (ECFP) transgene that lacks a 150 bp segment of the distal promoter, we have used to dissect the differentiation and CSF1 responsiveness of mononuclear phagocyte populations in situ. Consistent with previous Csf1r-driven reporter lines, Csf1r-mApple was expressed in blood monocytes and at higher levels in tissue macrophages, and was readily detectable in whole mounts or with multiphoton microscopy. In the liver and peritoneal cavity, uptake of labeled CSF1 largely reflected transgene expression, with greater receptor activity in mature macrophages than monocytes and tissue-specific expression in conventional dendritic cells. However, CSF1 uptake also differed between subsets of monocytes and discrete populations of tissue macrophages, which in macrophages correlated with their level of dependence on CSF1 receptor signaling for survival rather than degree of transgene expression. A double Delta Csf1r-ECFP-Csf1r-mApple transgenic mouse distinguished subpopulations of microglia in the brain, and permitted imaging of interstitial macrophages distinct from alveolar macrophages, and pulmonary monocytes and conventional dendritic cells. The Csf1r-mApple mice and fluorescently labeled CSF1 will be valuable resources for the study of macrophage and CSF1 biology, which are compatible with existing EGFP-based reporter lines