Calculating upper limb inertial parameters.

In the kinematic and kinetic analysis of human movement, an accurate assessment of the inertial properties of the body segments under investigation is often essential. Statistical and geometric models of the segments of the upper limb were examined to determine their ability to predict the moments of inertia of these segments. The cadaver data of Chandler et al. (1975) were used as the criteria with which computed values were compared. The regression equations of Hinrichs (1985) gave the most accurate results; the geometric models appeared to offer the greatest flexibility.     

Leg mass characteristics of accurate and inaccurate kickers – an Australian football perspective

Abstract

Athletic profiling provides valuable information to sport scientists, assisting in the optimal design of strength and conditioning programmes. Understanding the influence these physical characteristics may have on the generation of kicking accuracy is advantageous. The aim of this study was to profile and compare the lower limb mass characteristics of accurate and inaccurate Australian footballers. Thirty-one players were recruited from the Western Australian Football League to perform ten drop punt kicks over 20 metres to a player target. Players were separated into accurate (n = 15) and inaccurate (n = 16) groups, with leg mass characteristics assessed using whole body dual energy x-ray absorptiometry (DXA) scans. Accurate kickers demonstrated significantly greater relative lean mass (P ≤ 0.004) and significantly lower relative fat mass (P ≤ 0.024) across all segments of the kicking and support limbs, while also exhibiting significantly higher intra-limb lean-to-fat mass ratios for all segments across both limbs (P ≤ 0.009). Inaccurate kickers also produced significantly larger asymmetries between limbs than accurate kickers (P ≤ 0.028), showing considerably lower lean mass in their support leg. These results illustrate a difference in leg mass characteristics between accurate and inaccurate kickers, highlighting the potential influence these may have on technical proficiency of the drop punt.     

Adopting a models-based approach to teaching physical education

Background: The popularised notion of models-based practice (MBP) is one that focuses on the delivery of a model, e.g. Cooperative Learning, Sport Education, Teaching Personal and Social Responsibility, Teaching Games for Understanding. Indeed, while an abundance of research studies have examined the delivery of a single model and some have explored hybrid models, few have sought to meaningfully and purposefully connect different models in a school's curriculum (see Kirk, D. 2013. ‘Educational Value and Models-based Practice in Physical Education.’ Educational Philosophy and Theory 45 (9): 973–986.; Lund, J., and D. Tannehill. 2015. Standards-based Physical Education Curriculum Development. 3rd ed. Burlington, MA: Jones &; Bartlett.; Quay, J., and J. Peters. 2008. ‘Skills, Strategies, Sport, and Social Responsibility: Reconnecting Physical Education.’ Journal of Curriculum Studies 40 (5): 601–626.). Significantly none, to date, have empirically investigated broader notions of MBP that make use of a range of different pedagogical models in/through the PE curriculum (Kirk, D. 2013. ‘Educational Value and Models-based Practice in Physical Education.’ Educational Philosophy and Theory 45 (9): 973–986.).

Aim: To provide a first empirical insight into using a MBP approach involving several models to teach physical education. At its heart, this paper presents the reader with the realistic and nuanced challenges that arise in striving towards, engaging with, planning for, and enacting a broader, multimodel notion of MBP.

Method: While the study itself was broader, we focus primarily on three units (one using Cooperative Learning, one using a Tactical Games/Cooperative Learning hybrid and a third using Sport Education) taught to boys in two different age groups (i.e. 11–12 and 14–15). Two analytical questions inform and guide our enquiry: (1) What do we learn about MBP implementation through this project that would help other physical education practitioners implement a multimodel MBP approach? and (2) What are the key enablers and constraints of early MBP implementation? Data sources included (a) 21 semi-structured interviews with student groups, (b) teacher post-lesson and post-unit reflective analyses, (c) daily teacher reflective diaries, and (d) teacher unit diaries. Data were analysed comparatively considering the two analytical questions.

Results: The data analysis conveys strong themes around the areas of teacher and student prior learning, working toward facilitating a change in practice, sufficient time to consider changes in practice, and changing philosophies and practices. The results suggest that the consistent challenge that arose for the teacher towards the goal of adopting a MBP approach was the reduction of his overt involvement as a teacher. While the teacher bought into the philosophy of multimodel MBP he was continually frustrated at not progressing as quickly as he would like in changing his practice to match his philosophy.

Conclusions: Despite his best intentions, early attempts to use a multimodel MBP approach were limited by the teacher’s ability to re-conceptualise teaching. The teacher made ‘rookie mistakes’ and tried to transfer his normal classroom practice onto paper handouts while simultaneously inviting students to play a more central role in the classroom. In considering this journey, we can see an indication of the investment needed to implement a MBP approach. Pedagogical change in the form of MBP is a process that needs to be supported by a community of practice intent on improving learning across multiple domains in physical education.     

Estimation of aerobic fitness from PACER performance with and without body mass index

Purpose: To develop models to estimate aerobic fitness (VO₂max) from PACER performance in 10- to 18-year-old youth, with and without body mass index (BMI) as a predictor. Method: Youth (N = 280) completed the PACER and a maximal treadmill test to assess VO₂max. Validation and cross-validation groups were randomly formed to develop and examine accuracy of models. Participants were classified into FitnessGram® Healthy Fitness Zone categories based on measured and estimated VO₂max and criterion-referenced validity was evaluated. Results: Multiple correlations between measured and estimated VO₂max ranged from .70 to .73, with standard errors of estimate between 6.43 and 6.68 mL·kg^?1·min^?1. Accuracy with and without BMI was nearly identical. Overall, criterion-referenced validity evidence was moderate. Conclusion: Moderately accurate and feasible models were developed. Minimal improvement in accuracy was noted when BMI was added as a predictor. The model with PACER and age as predictors has a high level of utility for youth fitness testing.     

A method of providing accurate velocity feedback of performance on an instrumented kayak ergometer

On a kayak ergometer, an accurate simulation of the athlete-paddle-kayak system kinematics is essential for analysing the relationship between technique and performance. The purpose of this study was to establish a strong relationship between performances on flatwater and performances on an ergometer by means of propulsive force measurement and drag models. Two trials were performed by 12 kayakers in which they were first timed over 250 m of flatwater kayaking (the reference test) and were then asked to perform a trial of the same duration on the ergometer with the same perceived physical exertion. Three techniques for measuring propulsive force and three drag models generated nine combinations, which were all evaluated for their ability to estimate kayak velocity. For each combination, the distance covered by the athlete on the ergometer was simulated. A kayakers’ ergometer ranking was based on the average velocity in the ergometer trial. Both distance and ranking were compared to the on-water results. The simulation with the best combination of force measurement and drag model gave an accurate estimate of distance (253 ± 10.5 vs. 250 m) and ranking compared to the reference test.     

Development and field validation of an omni-domain power-duration model

ABSTRACT

Purpose: To validate and compare a novel model based on the critical power (CP) concept that describes the entire domain of maximal mean power (MMP) data from cyclists.

Methods: An omni-domain power-duration (OmPD) model was derived whereby the rate of W? expenditure is bound by maximum sprint power and the power at prolonged durations declines from CP log-linearly. The three-parameter CP (3CP) and exponential (Exp) models were likewise extended with the log-linear decay function (Om3CP and OmExp). Each model bounds W? using a different nonconstant function, W?eff (effective W?). Models were fit to MMP data from nine cyclists who also completed four time-trials (TTs).

Results: The OmPD and Om3CP residuals (4 ± 1%) were smaller than the OmExp residuals (6 ± 2%; P < 0.001). W?eff predicted by the OmPD model was stable between 120–1,800 s, whereas it varied for the Om3CP and OmExp models. TT prediction errors were not different between models (7 ± 5%, 8 ± 5%, 7 ± 6%; P = 0.914).

Conclusion: The OmPD offers similar or superior goodness-of-fit and better theoretical properties compared to the other models, such that it best extends the CP concept to short-sprint and prolonged-endurance performance.     

Development of an accelerometer-based multivariate model to predict free-living energy expenditure in a large military cohort

Abstract

This study developed a multivariate model to predict free-living energy expenditure (EE) in independent military cohorts. Two hundred and eighty-eight individuals (20.6 ± 3.9 years, 67.9 ± 12.0 kg, 1.71 ± 0.10 m) from 10 cohorts wore accelerometers during observation periods of 7 or 10 days. Accelerometer counts (PAC) were recorded at 1-minute epochs. Total energy expenditure (TEE) and physical activity energy expenditure (PAEE) were derived using the doubly labelled water technique. Data were reduced to n = 155 based on wear-time. Associations between PAC and EE were assessed using allometric modelling. Models were derived using multiple log-linear regression analysis and gender differences assessed using analysis of covariance. In all models PAC, height and body mass were related to TEE (P < 0.01). For models predicting TEE (r ² = 0.65, SE = 462 kcal · d^?1 (13.0%)), PAC explained 4% of the variance. For models predicting PAEE (r ² = 0.41, SE = 490 kcal · d^?1 (32.0%)), PAC accounted for 6% of the variance. Accelerometry increases the accuracy of EE estimation in military populations. However, the unique nature of military life means accurate prediction of individual free-living EE is highly dependent on anthropometric measurements.     

Validation of Weinbach's and Hanavan's Models for Computation of Physical Properties of the Forearm

Abstract

The purpose of the present study was to validate the Weinbach and the Hanavan models for the determinations of the forearm volume and center of mass. The study was conducted using 20 forearms from six male and four female cadavers. Results from the present investigation indicate that Weinbach's model is more accurate than Hanavan's model in estimating forearm volume and center of mass. The relative location of the center of mass and the center of volume was also investigated with the Weinbach model and these centers were found to coincide. The Hanavan model should be used only in the cases where the shape of the forearm closely resembles that of a truncated cone.     

A Latent Growth Curve Approach to Investigating Developmental Dynamics and Correlates of Change in Children's Perceptions of Physical Competence

Abstract

In both the physical and academic domains interest has recently grown regarding developmental change in children's perceptions of competence. Recent advances in statistical methodology, such as latent growth modeling, enable the researcher to analyze developmental trends from both an inter- and intraindividual perspective, thus serving to increase our understanding of correlates of change in perceived competence. Using latent growth modeling, the purpose of the present study was to investigate developmental change in children's perceived competence at physical skills, examining maturational factors and chronological age as possible correlates of change. Subjects were male adolescents (N = 94). Data were collected during the child's sixth, eighth, and ninth grade school years. Results revealed a good fit for the hypothesized model, which specified mean level changes in the variables over time and an interrelationship among the latent chronometric common factors. Although a significant relationship existed between maturation and perceived competence, no significant relationship was evident between chronological age and perceived competence. Findings are discussed with particular reference to the utility of latent growth curve models for assessing developmental processes at both the inter- and intraindividual level.     

The impact of limb deficiency impairment on Para swimming performance

ABSTRACT

Swimmers with limb deficiency are a core population within Para Swimming, accordingly this study examined the contribution of limb segments to race performance in these swimmers. Data were obtained for 174 male Para swimmers with limb deficiency. Ensemble partial least squares regression showed accurate predictions when using relative limb segment lengths to estimate Para swimmers’ personal best race performances. The contribution of limb segments to performance in swim events was estimated using these regression models. The analysis found swim stroke and event distance to influence the contributions of limb segments to performance. For freestyle swim events, these changes were primarily due to the increased importance of the hand, and decreased importance of the foot and shank, as the distance of the event increased. When comparing swim strokes, higher importance of the thigh and shank in the 100 m breaststroke compared with other swim strokes confirms the separate SB class. Varied contributions of the hand, upper arm and foot suggest that freestyle could also be separated from backstroke and butterfly events to promote fairer classification. This study shows that swim stroke and event distance influence the activity limitation of Para swimmers with limb deficiency suggesting classification should account for these factors.     

The BASES Expert Statement on Exercise and Cancer Survivorship

Abstract

Research examining the proximal-to-distal sequencing of segments of the body involved in overarm throwing has been equivocal: some studies have found support for the concept while others have not. The aim of the present study, therefore, was to determine if there is a proximal-to-distal sequence in the timing of the movements of joints and the distal endpoints of segments in overarm throwing. The three-dimensional kinematics of a penalty throw in experienced team handball players (n = 11) were recorded and analysed with regard to the timing of events. We analysed the timing of the maximal velocity of the distal endpoints of six segments and the maximal angular velocity in 11 joints, as well as the initiation of these joint movements. A temporal proximal-to-distal sequence was observed only for the initiation of the joint movements. No such sequence was found for maximal velocity of the joints and distal endpoints of segments.     

Self-belief does make a difference: A reciprocal effects model of the causal ordering of physical self-concept and gymnastics performance

Abstract

A large body of research in support of the reciprocal effects model of causal ordering demonstrates that prior academic self-concept predicts subsequent academic achievement beyond what can be explained in terms of prior achievement. Here we evaluate the generalizability of this support for the reciprocal effects model to a physical activity context in which achievement is reflected in gymnastics skills on a standardized gymnastics performance test evaluated by expert judges. Based on the responses of 376 adolescents collected at the start (T1) and end (T2) of a gymnastics training programme, there is support for a reciprocal effects model in which there are significant paths leading from both T1 gymnastics self-concept to T2 gymnastics skills and from T1 gymnastics skills to T2 self-concept. Although there were gender and age effects (girls and older participants had better gymnastics skills, boys had higher self-concepts), multiple group structural equation models indicated that support for the reciprocal effects model generalized over responses by boys and girls. In summary, self-concept and performance are both determinants and consequences of each other.     

The Acute Response of the Immune System to Tennis Drills in Adolescent Athletes

ABSTRACT

Purpose: The purpose of this study was to examine changes in school-based physical education (PE) attendance over time among nationally representative samples of U.S. high school students and how changes in PE attendance have varied across demographic subgroups. Method: Student demographic information and PE attendance data were obtained from 13 biennial cycles (1991–2015) of the national Youth Risk Behavior Survey (YRBS). Physical education variables derived from YRBS data included PE attendance, daily PE, average PE days/week, and PE frequency. Logistic regression models examined trends in PE attendance, daily PE, and PE frequency for the overall sample and demographic subgroups. Linear regression models examined trends in average PE days/week in the overall sample only. Results: Overall, there was no significant change in the percentage of students reporting PE attendance during 1991 to 2015. However, daily PE and average PE days/week declined significantly from 1991 to 1995 (41.6% to 25.4% and 4.64 days to 3.64 days, respectively) and then remained stable through 2015 (29.8% and 4.11 days, respectively). The percentage of students reporting a PE frequency of 3 days per week increased significantly from 1991 to 1995 (1.5% to 19.0%) before stabilizing through 2015 (9.1%). Trends across demographic subgroups revealed notable differences in PE attendance. Conclusions: Study findings showed that U.S. schools have not substantially reduced PE amounts in recent years. Still, the prevalence of PE attendance among U.S. high school students is well below recommendations. For PE to contribute to increased adolescent compliance with national physical activity guidelines, significant policy actions are needed to improve PE access for all students.     

Differences in ball speed and accuracy of tennis groundstrokes between elite and high-performance players

Abstract

The main aim of this study was to identify and compare ball speed and hitting accuracy of forehand and backhand groundstrokes between ATP professionals (elite) and high-performance youth players when shots were played cross-court and down the line to a target square. Six elite and seven high-performance tennis players volunteered to participate in the study. A Doppler-radar device and a digital video camera, operating at 120 frames per second, were used to measure ball speed and accuracy of forehand and backhand groundstrokes in the respective situation (cross-court and down the line). The results of 1040 measured groundstrokes indicate that the ball speed of the forehand and the backhand ground stroke was higher in the elite group when analysing (1) all valid shots, (2) the six fastest shots, and (3) the six most accurate shots (all P < 0.05). In addition, all players achieved a higher forehand speed compared with their backhand when balls were directed cross-court (P < 0.01). The participants demonstrated similar ability when considering accuracy of their groundstrokes (P > 0.05). However, a group difference for accuracy was identified when considering the six fastest forehand shots (P<0.05), and the forehand cross-court stroke was played more accurately than the backhand cross-court stroke by both groups (valid shots and six most accurate shots, P<0.05). Moreover, there was no evidence that players who impacted the ball faster were any less accurate than those who impacted the ball more slowly. Analyses for participants actually revealed a negative correlation between ball speed and mean radial error (accuracy) for the backhand down the line (r= ? 0.77, P<0.01). According to the results of this study, ball speed seems to be the determining factor that separates elite from sub-elite tennis players.     

Individual Differences and Similarities in the Stability,Timing Consistency,and Natural Frequency of Rhythmic Coordinated Actions

Abstract

Silhouette ratings of actual and ideal body fat (N = 258 high school students) were related to 4 self-concept scales (Body Fat, Physical Appearance, General Physical, Esteem) and objective body composition measures in order to test predictions from actual-ideal discrepancy models. Actual-ideal discrepancy scores were more strongly related to self-concept than actual scores alone, thus supporting the traditional discrepancy model. However, multiple regression analyses demonstrated that more sophisticated actual- ideal discrepancy models that considered discrepancies in either direction (feeling too fat or too thin) did significantly better. Because the traditional discrepancy model is a special case of this more general discrepancy model, the more general model should have broad applicability. Important aspects of this task were (a) that discrepancies were evaluated along a continuum in which the ideal was not one of the endpoints of the continuum, (b) that there was reasonable variation in ideal ratings, and (c) that positive and negative discrepancies were reported.     

Statistics,truth, and error reduction in sport and exercise sciences

Abstract

Academics have a responsibility to ensure that their research findings are as truthful as possible. InIn every issue of a scientific journal, a large number of significance tests are reported (usually using P <0.05). Of course, most of these results will be true/correct. Unfortunately, due to the nature of sampling, researchers will occasionally make errors, often referred to as type I (probability = α) and type II (probability = β) errors. The power of a test (1-β) is the probability of correctly rejecting a false null hypothesis – that is, correctly detecting a real or true effect. Factors that are known to influence power include: (1) the level of significance (α), (2) the size of the difference or relationship in the population (the effect), (3) the sample size, and (4) unexplained error variance. As researchers, we have little control over most of these factors. The one factor that we have some influence over, however, is the ability to reduce the unexplained error variance. In the present article, we describe a range of methods that will increase the probability that a researcher has correctly identified a real effect by increasing the power of their statistical tests. Such methods will include ways of designing experiments to reduce error and uncertainty. The use of blocking and randomized block designs will reduce unexplained error, such as adopting matched or repeated-measures designs rather than using independent observations. The other method of reducing unexplained errors is to adopt more appropriate (e.g. biologically correct) models and checking the distribution assumptions associated with such models. In conclusion, researchers are responsible for maximizing the likelihood that their results are as accurate and truthful as possible. By carefully planning their experiments and adopting appropriate models, researchers are more likely to publish their findings with a greater degree of confidence, but not certainty.     

Correlations between Success in Student Teaching and Success on the Job

Purpose: This exploratory study examined the notion of Seefeldt's (1980) hypothesized motor skill “proficiency barrier” related to composite levels of health-related physical fitness (HRF) in young adults. Method: A motor skill competence (MSC) index composed of maximum throwing and kicking speed and jumping distance in 187 young adults aged 18 to 25 years old was evaluated against a composite index of 5 health-related fitness (HRF) test scores. MSC (high, moderate, and low) and HRF indexes (good, fair, and poor) were categorized according to normative fitness percentile ranges. 2 separate 3-way chi-square analyses were conducted to determine the probabilities of skill predicting fitness and fitness predicting skill. Results: Most correlations among HRF and MSC variables by gender demonstrated low-to-moderate positive correlations in both men (12/15; r = .23–.58) and women (14/15; r = .21–.53). Chi-square analyses for the total sample, using composite indexes, demonstrated statistically significant predictive models, χ ² (1, N = 187) = 66.99, p < .001, Cramer's V = .42. Only 3.1% of low-skilled (2 of 65) individuals were classified as having a “good” HRF. Only 1 participant (out of 65) who demonstrated high MSC was classified as having “poor” HRF (1.5%). Conclusion: Although individual correlations among individual MSC and HRF measures were low to moderate, these data provide indirect evidence for the possibility of a motor skill “proficiency barrier” as indicated by low composite HRF levels. This study may generate future research to address the proficiency barrier hypothesis in youth as well as adults.     

One-Parameter Item Response Theory Models for Psychomotor Tests Involving Repeated,Independent Attempts

Abstract

Three one-parameter item response theory models are given as viable models that describe the observed score probabilities of an examinee who takes a multiple attempts, single-item test of a psychomotor skill. These models include the Binomial Trials Model, the Poisson Counts Model, and the Inverse Binomial Model. The paper presents these models and offers suggestions for their estimation and subsequent use in the assessment of psychomotor behavior.     

Evaluation of the exercise workload of broadcast calisthenics for children and adolescents aged 11–17 years

Abstract

The aim of this study was to examine the exercise workload of the 3rd Series of National Broadcast Calisthenics for Elementary and Middle School Students. Altogether, 120 students aged 11–17 years were randomly selected from elementary and middle schools to participate in the study. Each participant performed a cycle ergometer test to obtain maximum oxygen uptake ([Vdot]O_2max) and maximum heart rate values. In the laboratory, oxygen uptake ([Vdot]O₂), metabolic equivalents (METs), and heart rate were recorded continuously throughout a calisthenics session performed by the participants. Ratings of perceived exertion (RPE) were also recorded. Throughout the calisthenics session, mean percentage of [Vdot]O₂ reserve varied from 30.7% to 41.2%, mean percentage of heart rate reserve from 39.0% to 56.9%, and mean RPE from 9.0 to 10.4. The mean energy cost during most of the segments across the four routines of calisthenics was significantly higher (P < 0.05) than 3.0 METs. In conclusion, the exercise workload of the 3rd Series of National Broadcast Calisthenics for Elementary and Middle School Students session varied from low to moderate. As part of a school-based physical activity intervention project, calisthenics would help to promote an active lifestyle and health in children and adolescents.     

Developing the practising model in physical education: an expository outline focusing on movement capability

Background: Physical educators currently have a number of pedagogical (or curricular) models at their disposal. While existing models have been well-received in educational contexts, these models seek to extend students’ capacities within a limited number of ‘human activities’ (Arendt, 1958). The activity of human practising, which is concerned with the improvement of the self, is not explicitly dealt with by current models.

Purpose: The aim of the paper is to outline how a model of human practising related to movement capability could be enacted in physical education.

Findings: Building on a theoretical exposition of human practising presented in a separate paper, this paper provides a practically oriented discussion related to: (1) the general learning outcomes as well as teaching and learning strategies of the model; (2) an outline of five activities that describe how the model could be implemented; and (3) the non-negotiable features of the model.

Discussion: The model’s potential contribution to the ongoing revitalization of PE as an institutionalized educational practice is discussed. Points concerning how the model relates to wider physical cultures, its position regarding transfer of learning, standards of excellence, and social and cultural transmission are considered.

Conclusion: The paper is concluded with some reflections on pedagogical models generally and how they relate to the pedagogical model of practising movement capability presented in this paper.