Infrared reflection absorption spectroscopy setup with incidence angle selection for surfaces of non-metals.

Infrared Reflection Absorption Spectroscopy (IRAS) on dielectric single crystals is challenging because the optimal incidence angles for light-adsorbate interaction coincide with regions of low IR reflectivity. Here, we introduce an optimized IRAS setup that maximizes the signal-to-noise ratio for non-metals. This is achieved by maximizing light throughput and by selecting optimal incidence angles that directly impact the peak heights in the spectra. The setup uses a commercial Fourier transform infrared spectrometer and is usable in ultra-high vacuum (UHV). Specifically, the optical design features sample illumination and collection mirrors with a high numerical aperture inside the UHV system and adjustable apertures to select the incidence angle range on the sample. This is important for p-polarized measurements on dielectrics because the peaks in the spectra reverse the direction at the Brewster angle (band inversion). The system components are connected precisely via a single flange, ensuring long-term stability. We studied the signal-to-noise ratio (SNR) variation in p-polarized IRAS spectra for one monolayer of CO on TiO2(110) as a function of incidence angle range, where a maximum SNR of 70 was achieved at 4 cm-1 resolution in a measurement time of 5 min. The capabilities for s polarization are demonstrated by measuring one monolayer D2O adsorbed on a TiO2(110) surface, where a SNR of 65 was achieved at a peak height ΔR/R0 of 1.4 × 10-4 in 20 min.

Injury prevention for women and girls playing Australian Football: programme cocreation, dissemination and early adopter coach feedback.

Background: Adherence to injury prevention programmes may improve with greater end-user involvement and application of implementation frameworks during development. We describe the cocreation, initial dissemination and feedback from programme early adopters (coaches), to develop the first evidence-informed injury prevention programme for women playing community Australian Football (Prep-to-Play). Methods: We used a pragmatic seven-step process for developing sports injury prevention programmes to (1) gain organisational support, (2) compile research evidence, (3) consult experts, (4) engage end-users, (5) test programme acceptability, (6) evaluate against theory and (7) gain early adopter feedback. All Australian Football-registered coaches of women's/girls' teams were sent a postseason survey to determine initial awareness, adoption and implementation (steps 5 and 6). Purposively selected coaches were invited to interviews/focus groups (step 7) to identify competency, organisational and leadership implementation drivers with a deductive thematic analysis applied. Results: Prep-to-Play was cocreated using previous efficacious programmes and expert input (steps 1-4), and disseminated via the national sporting organisation in preseason 2019 to all registered coaches (step 5). 343 coaches (90 women) completed the postseason survey and 22 coaches (5 women) participated in an interview (n=9) or focus group (n=13) (steps 6 and 7). 268 coaches (78%) were aware of Prep-to-Play. Of those aware, 218 (81%) had used (at least one element) Prep-to-Play, and 143 (53%) used it at least twice per week. Competency drivers included local expert-delivered face-to-face workshops complimented by online content and ongoing support. Organisational drivers included coach education integrated into existing league/club. Leadership drivers included compulsory injury prevention education integrated into coach reaccreditation processes or incentivisation via recognition (eg, professional development points). Conclusions: Cocreation and organisational support resulted in high programme awareness and adoption. However, high fidelity implementation and maintenance may need to be facilitated by competency, organisational and leadership drivers. Responsibility should be shared among all stakeholders.

Correction to "Why and How Savitzky-Golay Filters Should Be Replaced".

[This corrects the article DOI: 10.1021/acsmeasuresciau.1c00054.].

Why and How Savitzky-Golay Filters Should Be Replaced.

Savitzky-Golay (SG) filtering, based on local least-squares fitting of the data by polynomials, is a popular method for smoothing data and calculations of derivatives of noisy data. At frequencies above the cutoff, SG filters have poor noise suppression; this unnecessarily reduces the signal-to-noise ratio, especially when calculating derivatives of the data. In addition, SG filtering near the boundaries of the data range is prone to artifacts, which are especially strong when using SG filters for calculating derivatives of the data. We show how these disadvantages can be avoided while keeping the advantageous properties of SG filters. We present two classes of finite impulse response (FIR) filters with substantially improved frequency response: (i) SG filters with fitting weights in the shape of a window function and (ii) convolution kernels based on the sinc function with a Gaussian-like window function and additional corrections for improving the frequency response in the passband (modified sinc kernel). Compared with standard SG filters, the only price to pay for the improvement is a moderate increase in the kernel size. Smoothing at the boundaries of the data can be improved with a non-FIR method, the Whittaker-Henderson smoother, or by linear extrapolation of the data, followed by convolution with a modified sinc kernel, and we show that the latter is preferable in most cases. We provide computer programs and equations for the smoothing parameters of these smoothers when used as plug-in replacements for SG filters and describe how to choose smoothing parameters to preserve peak heights in spectra.

With Crisis Comes Opportunity: Redesigning Performance Departments of Elite Sports Clubs for Life After a Global Pandemic.

The suspension of major sporting competitions due to the global COVID-19 pandemic had a substantial negative impact on the sporting industry. As such, a successful and sustainable return to sport will require extensive modifications to the current operations of sporting organizations. In this article we argue that methods from the realm of sociotechnical systems (STS) theory are highly suited for this purpose. The aim of the study was to use such methods to develop a model of an Australian Football League (AFL) club's football department. The intention was to identify potential modifications to the club's operations to support a return to competition following the COVID-19 crisis. Subject Matter Experts from an AFL club participated in three online workshops to develop Work Domain Analysis and Social Organization and Cooperation Analysis models. The results demonstrated the inherent complexity of an AFL football department via numerous interacting values, functions and processes influencing the goals of the system. Conflicts within the system were captured via the modeling and included pursing goals that may not fully reflect the state of the system, a lack of formal assessment of core values, overlapping functions and objects, and an overemphasis on specialized roles. The current analysis has highlighted potential areas for modification in the football department, and sports performance departments in general.

Enhancing foot velocity in football kicking: the role of strength training.

In all codes of football, it is advantageous to be able to achieve a high ball speed or distance in a kick. An important determinant of ball speed and kick distance is the velocity of the foot at impact with the ball. Therefore, it is of interest to strength and conditioning practitioners to identify training programs that can increase foot velocity. The purpose of this review is to identify the factors influencing kicking performance and the research evidence relating to resistance training designed to enhance foot velocity in kicking. The review has been divided into 3 main sections. The first addresses the biomechanics of kicking to provide insights into the physical demands. The second section reviews the relationships between various measures of strength with performance indicators of maximum kicking, and the third part explores the research investigating the effects of resistance training on maximum kicking performance. Kicking can be described as a skill involving proximal-to-distal muscle activation. Foot velocity is determined by a complex sequencing of hip flexor and knee extensor concentric contractions and also involves hip extensor and knee flexor activation to assist with movement control. Research reporting correlations between strength and kicking performance support the importance of hip flexor and quadriceps strength. Although unclear, there is some evidence that adequate strength of the support leg, trunk muscles, hip adductors, and the muscles that control pelvic rotations are important. Strength training studies have shown that foot velocity and kicking performance can be enhanced by supplementary programs to regular football training, especially in nonelite athletes. Potentially valuable training includes plyometrics, exercises that simulate the whole kicking action, and kicking weighted balls. Exercises that isolate parts of the kicking action are not recommended because these do not appear to transfer well to kicking performance. There are many unanswered questions that await future research.

Acute effect of exercise on kicking accuracy in elite Australian football players.

Kicking accuracy (KA) is an important skill in Australian football but the potential influence of exercise on this skill has not been previously investigated. The purpose of this study was to determine if a 2x2min time trial running protocol influenced short KA in elite Australian football. Another aim was to identify if endurance, playing experience and position were related to any exercise-induced KA changes. Twenty-seven professional footballers performed a KA test by kicking at a bullseye on a target projected onto a screen. The mean error from the centre of the target was the KA score. The players were assessed on the KA test, and then performed a 2x2min time trial with a 3-min recovery between runs. The total distance covered was used as a measure of endurance fitness, and the test also served as an exercise bout designed to impose some physiological stress. Immediately following this test, the players walked into the laboratory and performed the KA test again. A paired t-test revealed that the whole group achieved a non-significant 2.7% improvement in KA. Players were divided into two distinct groups based on endurance (2x2min results), playing experience and position (midfielders and forwards/backs). Analysis of covariance showed that after the exercise bout, the fitter group had significantly better KA (p=0.010) than the less fit group, and the more experienced players were 16% more accurate than the less experienced group (p=0.055). The midfielders were 8.2% better than the forwards/backs in KA (p=0.32). It was suggested that greater endurance and playing experience may facilitate KA under moderate physiological stress.

Fast bowling arm actions and the illegal delivery law in men's high performance cricket matches.

This study investigated the bowling arm kinematics of 21 elite fast bowlers (mean +/- SD; age = 27.8 +/- 3.9 years) while performing in test, tour and one day international matches. Thirty-one of the 34 deliveries analysed exhibited straightening at the elbow joint (straightening min = 3 degrees, max = 22 degrees, mean +/- SD = 9 +/- 5 degrees), which by strict definition in the 2000 laws of cricket made them illegal. Five deliveries from three bowlers exhibited hyperextension of the bowling elbow (19 +/- 5 degrees). When assessed against an arbitrary threshold of 15 degrees for elbow straightening, ball speeds for deliveries above this threshold (39.5 +/- 2.0 m/s) were significantly faster (effect size = 1.4; p = 0.006) than deliveries below it (37.1 +/- 1.4 m/s). When grouped by delivery length, the bouncers and short deliveries recorded more elbow straightening (12 +/- 6.6 degrees) than the good length deliveries (9 +/- 4.4 degrees) and the full deliveries (8 +/- 5.7 degrees), although these were not statistically significant differences. The results of this study support the implementation of a tolerance threshold for assessing the legality of fast bowling actions. Further research is recommended into in-match kinematic modelling, laboratory based assessments of illegal bowling actions, perceptual aspects of bowling actions and remedial methods to reduce elbow straightening in bowling actions.

Using paid radio advertisements to promote physical activity among Arkansas tweens.

INTRODUCTION: The level of physical activity among children is a growing concern. Evidence shows that many children aged 9 to 13 years (tweens) do not participate in any organized physical activity during their nonschool hours, and some do not engage in any free-time physical activity. Physical inactivity is associated with a host of chronic diseases such as diabetes and cardiovascular disease. Paid media advertisements have been an effective method of promoting physical activity. METHODS: From March 10, 2003, through June 29, 2003, we aired paid radio advertisements in six major Arkansas metropolitan areas to promote physical activity among tweens. In September 2003, we surveyed 295 Arkansas tweens by telephone to assess their exposure to the advertisements and the impact of the advertisements on their intent to participate in physical activity. In the same telephone survey, we also asked questions about the respondents' physical activity level. The data were weighted so that the results would be representative of the areas surveyed. The statistical analysis was performed using SPSS, version 11.5 (SPSS Inc, Chicago, Ill). RESULTS: Of the tweens surveyed, 56.4% (95% confidence interval [CI], 50.7%-62.1%) reported hearing the radio advertisements. Of the tweens who heard the advertisement messages, 76.1% (95% CI, 69.4%-82.8%) said the messages made them more likely to get involved in physical activity. Younger tweens (aged 9 and 10 years) were less likely to have heard the advertisements than older tweens (aged 11 to 13 years). However, the advertisements were more likely to cause younger tweens to want to get involved in physical activity (odds ratio [OR] = 6.89, P = .003) than older tweens. Of the tweens surveyed, 74.9% (95% CI, 70.0%-79.8%) reported that they were involved in nonschool-sponsored sports, and 45.3% (95% CI, 39.6%-51.0%) were involved in school-sponsored sports. CONCLUSION: Paid media advertisements may be an effective way to promote physical activity among tweens. More rigorous evaluations of the impact of paid media advertisements among tweens, with larger samples and additional media markets, are needed. Future physical activity promotion efforts should focus on encouraging participation in school-sponsored sports and creating community environments conducive to physical activity.

Changes in three dimensional lumbo-pelvic kinematics and trunk muscle activity with speed and mode of locomotion.

BACKGROUND: Control of the trunk is critical for locomotor efficiency. However, investigations of trunk muscle activity and three-dimensional lumbo-pelvic kinematics during walking and running remain scarce. METHODS: Gait parameters and three-dimensional lumbo-pelvic kinematics were recorded in seven subjects. Electromyography recordings of abdominal and paraspinal muscles were made using fine-wire and surface electrodes as subjects walked on a treadmill at 1 and 2 ms(-1) and ran at 2, 3, 4 and 5 ms(-1). FINDINGS: Kinematic data indicate that the amplitude but not timing of lumbo-pelvic motion changes with locomotor speed. Conversely, a change in locomotor mode is associated with temporal but not spatial adaptation in neuromotor strategy. That is, peak transverse plane lumbo-pelvic rotation occurs at foot strike during walking but prior to foot strike during running. Despite this temporal change, there is a strong correlation between the amplitude of transverse plane lumbo-pelvic rotation and stride length during walking and running. In addition, lumbo-pelvic motion was asymmetrical during all locomotor tasks. Trunk muscle electromyography occurred biphasically in association with foot strike. Transversus abdominis was tonically active with biphasic modulation. Consistent with the kinematic data, electromyography activity of the abdominal muscles and the superficial fibres of multifidus increased with locomotor speed, and timing of peak activity of superficial multifidus and obliquus externus abdominis was modified in association with the temporal adaptation in lumbo-pelvic motion with changes in locomotor mode. INTERPRETATION: These data provide evidence of the association between lumbo-pelvic motion and trunk muscle activity during locomotion at different speeds and modes.

Are anthropometric and kinematic parameters of the lumbo-pelvic-hip complex related to running injuries?

The purpose of the experiment was to test whether specific anthropometric or kinematic parameters of the lumbo-pelvic-hip complex were related to running injuries. A case-control design was used to compare a group of 22 runners with a history of injury within the previous 12 months to a group of 19 injury-free controls. All runners were pain-free at the time of measurement. Groups were matched for self-reported average running volume per week and average number of running sessions per week. Anthropometric and kinematic parameters, previously speculated as being related to running injuries, were selected for evaluation. Running trials were conducted on a treadmill at a speed of 4.0 m/sec. The three-dimensional angular rotations of the lumbar spine, pelvis, and hip during running were measured using a VICON motion analysis system with seven cameras operating at a sampling rate of 200 Hz. None of the measured anthropometric or kinematic parameters were found to be significantly different between the injured and control groups. Despite the theoretical rationale, no evidence was found in the current experiment demonstrating a clear relationship between anthropometric or kinematic parameters of the lumbo-pelvic-hip complex and running injuries.

Postural and respiratory activation of the trunk muscles changes with mode and speed of locomotion.

Despite the importance of the deep intrinsic spinal muscles for trunk control, few studies have investigated their activity during human locomotion or how this may change with speed and mode of locomotion. Furthermore, it has not been determined whether the postural and respiratory functions, of which these muscles take part, can be coordinated when locomotor demands are increased. EMG recordings of abdominal and paraspinal muscles were made in seven healthy subjects using fine-wire and surface electrodes. Measurements were also made of respiration and gait parameters. Recordings were made for 10s as subjects walked on a treadmill at 1 and 2 ms(-1) and ran at 2, 3, 4 and 5 ms(-1). Unlike the superficial muscles, transversus abdominis was active tonically throughout the gait cycle with all tasks, except running at speeds of 3 ms(-1) and greater. All other muscles were recruited in a phasic manner. The relative duration of these bursts of activity was influenced by speed and/or mode of locomotion. Activity of all abdominal muscles, except rectus abdominis (RA), was modulated both for respiration and locomotor-related functions but this activity was affected by the speed and mode of locomotion. This study provides evidence that the deep abdominal muscles are controlled independently of the other trunk muscles. Furthermore, the pattern of recruitment of the trunk muscles and their respiratory and postural coordination is dependent on the speed and mode of locomotion.

Differences between the sexes in the three-dimensional angular rotations of the lumbo-pelvic-hip complex during treadmill running.

The aims of this experiment were to determine whether there are differences between the sexes in the three-dimensional angular rotations of the lumbo-pelvic-hip complex during running and, if such differences exist, to establish whether factors other than sex can explain the observed differences. A cohort of 44 non-injured runners (22 males, 22 females) who usually ran more than 20 km per week were voluntarily recruited. All trials were conducted on a treadmill at a running speed of 4.0 m x s(-1). Reflective markers were placed over specific anatomical landmarks of the thoraco-lumbar spine, pelvis and femur. Data were captured using a VICON motion analysis system. Females tended to display a greater peak-to-peak oscillation for most of the angular rotations. An offset was the main difference between the male and female group mean waveforms for pelvis anterior-posterior tilt. Forward stepwise regression analysis revealed that sex was the most common variable related to the amplitudes of the angular rotations. Given these results, sport scientists conducting future biomechanical studies using angular data to test hypotheses are advised to be extremely cautious about averaging across male and female participants.

Three-dimensional angular kinematics of the lumbar spine and pelvis during running.

The objective of this study were to: (i) describe the typical three-dimensional (3D) angular kinematics of the lumbar spine and pelvis during running and; (ii) assess whether the movements of the lumbar spine and pelvis during running are coordinated. A cohort of 20 non-injured male runners who usually ran >20 km/week were voluntarily recruited. All trials were conducted on a treadmill at a running speed of 4.0 m/second. Reflective markers were placed over anatomical landmarks of the thoraco-lumbar spine and pelvis. Data were captured using a VICON motion analysis system. The lumbar spine and pelvis both displayed complex 3D angular kinematic patterns during running. High correlations were found for the comparisons of flexion-extension of the lumbar spine with anterior-posterior tilt of the pelvis (r=-0.84) and lateral bend of the lumbar spine with obliquity of the pelvis (r=-0.75). However, a poor correlation was found for the comparison of axial rotation of the lumbar spine with axial rotation of the pelvis (r=0.37). A phase difference of 21% of the running cycle was evident between axial rotation of the lumbar spine and pelvis. The identified coordinated kinematic patterns of the lumbar spine and pelvis during running serve as a basis for future investigations exploring the relationship between atypical kinematic patterns and injury.

Intra-subject repeatability of the three dimensional angular kinematics within the lumbo-pelvic-hip complex during running.

The intra-subject repeatability of measuring the three dimensional (3D) angular kinematics of the lumbo-pelvic-hip complex during running was evaluated. Spatio-temporal parameters were found to be repeatable. All angular kinematic parameters displayed high within-day repeatability despite numerous potential sources of variability in the data. Most angular kinematic parameters also displayed high between-day and overall repeatability, except for trunk flexion-extension, lumbar spine flexion-extension, pelvic anterior-posterior tilt, hip axial rotation and thigh axial rotation. These angular parameters were highly susceptible to marker reapplication errors that produced static daily offsets in the data. Overall, the results of this study suggest that the 3D angular kinematic patterns of the lumbo-pelvic-hip complex during running can be measured with sufficient repeatability to justify the implementation of the method as an evaluation tool in future investigations. However, caution must be exerted when interpreting the absolute magnitudes of trunk flexion-extension, lumbar spine flexion-extension, pelvic anterior-posterior tilt, hip axial rotation and thigh axial rotation, given the poor level of repeatability found for these measures.