Development Of An Anthropomorphic Thigh For Impact Assessment

Modelling of body segments allows predictions to be made of their response characteristics during interactions with the environment. Once the segment or whole body has been replicated, their response to impact can be investigated. This along with an injury tolerence level provides an opportunity to assess the effectiveness of protective equipment. Head/neck models are used by the helmet industry to assess the effectiveness of crash and sport helmets. Wholebody models are used in the automotive and aircraft industries. No instrumented physical thigh model has been designed to assess soft tissue strain as a result of transverse impacts to the longitudinal axis. There is no appropriate means to assess the protection from injury of the numerous thigh pads used in sport. The aims of this study are: i) Determine the response of the human thigh (and its components) to transverse impacts to the longitudinal axis. ii) Select injury tolerence levels for thigh contusions. iii) Select synthetic materials with similar mechanical properties to those of the human thigh (muscle, skin and fat). iv) Design an instrumented physical model of the leg capable of predicting thigh contusions. The subjects will be seated with their thigh horizontal and a knee angle of 120 degrees. An ankle strap will be attached to a load cell. Testing will be performed at a given percent of maximal voluntary isometric cantraction for knee extension. A hemispherical striker under guided free-fall will impact the anterior mid thigh. An accelerometer will be mounted to the striker. Various drop heights may be employed dependinq on subject discomfort. Subjects have volunteered to an impact which will result in a thigh contusion. Testing will be carried out under medical supervision. Thigh skinfold and girth measurements will be taken. To estimate the internal force and the amount of dampening offerred by the biological components, cadaver material will be tested at drop heights which produced contusions in living subjects. Intact anterior thigh tissue (muscle, fascia, fat and skin) will be placed on a force platform and drop tests performed. The components (muscle, skin and fat) will also be assessed separately. Synthetic materials to represent muscle and skin and fat should display similar dampening properties as determined from cadaver impact tests. A force transducer positioned under the synthetic materials can then estimate the internal force and predict contusions

RISK OF HEAD INJURY FROM FALLS ON TAEKWONDO MATS

The aim of this project was to determine the risk of head injury from falls without protective headgear onto 5 different taekwondo mats. In addition, the combined shock absorption of the headgear and mats adopted by the Australian taekwondo team was assessed. An artificial headform with accelerometers was dropped from a height of 1.5 m onto the mats. The acceleration data were used to calculate the Head Injury Criterion (HIC). Results revealed that only one mat had sufficient shock absorption to generate a HIC value below the threshold for head injury for drops with the unprotected headfotm. The combination of the protective headgear and mats adopted by the Australian taekwondo team produced HIC values below the injury threshold. It is recommended that taekwondo athletes wear protective headgear at all times when training

The reliability of a new functional balance protocol for use in sports requiring jump landing tasks

Background: The current gold standard of balance testing within elite academy football has been shown to be time consuming and contain movement requirements non-specific to football. Purpose: To assess the reliability of a new balance protocol for use in elite academy football, due to the difficulty in testing large group sizes and the limited movements patterns with the current gold standard tests. Methods: 10 Participants completed a series of functional jumps, incorporating forward, lateral and vertical movement and landing strategies, with single leg landings. The participants’ jumps were videoed for retrospective analysis as well as scored in real time by two observers. The subjects balance abilities were graded based on pre-determined criteria derived from the current gold standards of balance testing. Both intra and inter-tester reliability of the functional balance protocol was assessed. Main Results: The results show the FBP has ‘excellent’ inter-rater reliability for both real-time analysis and retrospective video analysis, with correlation coefficients ranging from 0.864 to 0.950. Conclusions: The FBP has excellent intra and inter-rater reliability. The research supplies evidence to suggest that using a functional protocol with an objective fail criteria combining current “gold standard” balance tests, in conjunction with minimal equipment and a short testing duration may be a more appropriate method to test balance

Pressure sensor calibration for measuring stud-player impacts

In rugby union, laceration injuries can occur from players stamping on opponents in the ruck. To measure the stud-skin interaction during stamping movements, pressure sensors can be used. Pressure sensor calibration techniques have highlighted the need to perform calibrations using appropriate impact dynamics. A pilot study with seven rugby players informed the expected peak forces and loading rates of rugby stamps. Subsequently, a custom calibration procedure was developed, using a drop hammer and force platform to replicate the experimentally observed forces and loading rates. The conventional calibration of the pressure sensor system, supplied by the manufacturer, overestimated total force by 132%. The method described in this paper resulted in a mean error of 7.5%. This study describes a simple and effective calibration procedure for using pressure sensors when measuring the peak force from stud-player impacts. The method has potential to be used as an improved calibration protocol when the expected peak force range of the measured event is between 1800 and 3000 N. The calibrated pressure sensors will be used to obtain kinetic data from stamping events in the ruck in rugby union

Effects of training on postural control and agility when wearing socks of different compression levels

Study aim: The aim of this study was to evaluate the effects of training while wearing socks differing in compression level (clinical, sub-clinical, regular) on performance of static and dynamic balancing and agility tasks in healthy, physically active people. We sought to understand whether socks with different compression properties supported postural regulation and agility task performance by enhancing somatosensory perception, unskewed by specific age range effects. Material and methods: Participants comprised 61 adults aged 18-75 years, divided into three groups (two experimental groups wearing clinical or sub-clinical level compression socks, and one control group wearing regular non-compression socks during training). An 8-week (2 × 1h per week) intervention programme was administered to train static and dynamic balance and postural control, leg strength and agility. Results: A mixed model ANOVA revealed no differences in static and dynamic balance and postural control and agility performance between clinical, sub-clinical, and control groups before and after training. All groups significantly improved their test performance, suggesting that training had some benefit on motor performance. Conclusions: These results raised interesting questions requiring further investigation to examine the effects of wearing socks (with and without different levels of compression) on motor behaviours in specific groups of elderly vs. young participants, in physically active vs. less physically active people, and in performance settings outside standardized laboratory tests to study applications in natural performance environments

Changes in balance ability, power output, and stretch-shortening cycle utilisation after two high-intensity intermittent training protocols in endurance runners

Purpose: This study aimed to describe the acute effects of 2 different high-intensity intermittent trainings (HIITs) on postural control, countermovement jump (CMJ), squat jump (SJ), and stretch-shortening cycle (SSC) utilisation, and to compare the changes induced by both protocols in those variables in endurance runners.Methods: Eighteen recreationally trained endurance runners participated in this study and were tested on 2 occasions: 10 runs of 400 m with 90 s recovery between running bouts (10 × 400 m), and 40 runs of 100 m with 30 s recovery between runs (40 × 100 m). Heart rate was monitored during both HIITs; blood lactate accumulation and rate of perceived exertion were recorded after both protocols. Vertical jump ability (CMJ and SJ) and SSC together with postural control were also controlled during both HIITs.Results: Repeated measures analysis revealed a significant improvement in CMJ and SJ during 10 × 400 m (p < 0.05), whilst no significant changes were observed during 40 × 100 m. Indexes related to SSC did not experience significant changes during any of the protocols. As for postural control, no significant changes were observed in the 40 × 100 m protocol, whilst significant impairments were observed during the 10 × 400 m protocol (p < 0.05).Conclusion: A protocol with a higher number of shorter runs (40 × 100 m) induced different changes in those neuromuscular parameters than those with fewer and longer runs (10 × 400 m). Whereas the 40 × 100 m protocol did not cause any significant changes in vertical jump ability, postural control or SSC utilisation, the 10 × 400 m protocol impaired postural control and caused improvements in vertical jumping tests.Open Access funded by Shanghai University of Spor

Low-Back Pain and Knee Position–Related Differences on Postural Control Measures During a One-Legged Stance in Athletes

Abstract : Context: Chronic low-back pain (CLBP) may be associated with changes in postural balance in athletes as poor postural control during sports practice. Objective: To compare the postural control of athletes with and without CLBP during 2 one-legged stance tasks and identify the center of pressure (COP) cutoff values to determine the main differences. Designed: A cross-sectional study. Setting: Laboratory of functional evaluation and human motor performance. Participants: A total of 56 male athletes, 28 with and 28 without CLBP (mean age = 26 y). Intervention: The one-legged stance with knee extension and with the knee at 30° flexion tasks were measured and analyzed on a force platform. The participants completed three 30-second trials (30 s of rest between each trial). Main Outcome Measures: The COP parameters: the area of COP, mean COP sway velocity in both the anteroposterior and mediolateral directions, and total COP displacement were computed, and a receiver operating characteristics curve analysis was applied to determine the group differences. Results: Athletes with CLBP had poorer postural control (P 7.1 cm2 for the COP area, >2.6 cm/s for the COP sway velocity in the anterior-posterior direction, and >3.2 cm/s for the mediolateral direction. Whereas, the 30° knee flexion cutoffs were >10.9 cm2 for the COP area, >2.9 cm/s for the COP sway velocity in the anterior-posterior direction, and >4.1 cm/s for the mediolateral direction. Both measures showed enough sensitivity and specificity (ie, area under the curve = 0.88 in and 0.80, respectively) to discriminate both groups. Conclusions: The athletes with CLBP had poorer postural control than the healthy athletes and obtained specific cutoff scores from the COP values