Event-specific impact test protocol for ice hockey goaltender masks

ABSTRACT

Goaltenders in the sport of ice hockey are at high risk for concussions from falls to the ice, player collisions and puck impacts. However, current methods used to certify helmets only consider head accelerations for drop tests which may not describe all common injury mechanisms relating to concussion. The purpose of this study was to describe the characteristics of 3 events associated with concussions for ice hockey goaltenders. A helmeted medium National Operating Committee on Standards for Athletic Equipment (NOCSAE) headform was impacted under conditions representing 3 injury events. Three impact locations’ velocities were selected for each event based on video analysis of real-world concussive events. Peak resultant linear acceleration, rotational acceleration and rotational velocity of the headform were measured. The University College Dublin Brain Trauma Model (UCDBTM) was used to calculate maximum principal strain (MPS) and von Mises stress in the cerebrum. Each impact event produced a unique dynamic response and brain stress and strain values. This demonstrates that a single impact event (i.e. falls) cannot adequately describe all impact events. As a result, impact protocols which assess multiple impact events such as the protocol described in this study should be used to evaluate ice hockey goaltender masks.     

Compressive properties of helmet materials subjected to dynamic impact loading of various energies

Abstract

Many helmet safety standards require children's helmets to be tested using adult-weighted headforms of approximately 5 kg and impact velocities representative of adult anatomy. The purpose of this study was to test the individual and combined effect of variable headform mass and inbound headform velocity on helmet test results. Testing was conducted on sample sections of helmet liner materials commonly used in multi- and single-impact helmets. Three densities of expanded polystyrene and expanded polypropylene were moulded into 2.54-cm thick foam blocks and cut into circular samples with a 5-cm diameter. Each sample was impacted once using an EN 960 magnesium K1A headform of variable mass on a monorail apparatus in the crown position. A total of 25 impact conditions were used: 5 headform masses and 5 inbound velocities. A PCB 203B force sensor collected force data at 20 kHz in the y-axis of the impact and a 1000-Hz low-pass Butterworth filter was applied during analysis. A three-way analysis of variance revealed significant main effects for headform mass, inbound velocity, and material density on peak linear acceleration (P<0.01). Inbound velocity and headform mass played a significant role in material performance. It is proposed that the headform mass and inbound velocity used in helmet testing protocols be representative of the intended age group to improve the performance range and safety of sport helmets.     

Heat transfer variations of bicycle helmets

Abstract

Bicycle helmets exhibit complex structures so as to combine impact protection with ventilation. A quantitative experimental measure of the state of the art and variations therein is a first step towards establishing principles of bicycle helmet ventilation. A thermal headform mounted in a climate-regulated wind tunnel was used to study the ventilation efficiency of 24 bicycle helmets at two wind speeds. Flow visualization in a water tunnel with a second headform demonstrated the flow patterns involved. The influence of design details such as channel length and vent placement was studied, as well as the impact of hair. Differences in heat transfer among the helmets of up to 30% (scalp) and 10% (face) were observed, with the nude headform showing the highest values. On occasion, a negative role of some vents for forced convection was demonstrated. A weak correlation was found between the projected vent cross-section and heat transfer variations when changing the head tilt angle. A simple analytical model is introduced that facilitates the understanding of forced convection phenomena. A weak correlation between exposed scalp area and heat transfer was deduced. Adding a wig reduces the heat transfer by approximately a factor of 8 in the scalp region and up to one-third for the rest of the head for a selection of the best ventilated helmets. The results suggest that there is significant optimization potential within the basic helmet structure represented in modern bicycle helmets.     

The impact absorption characteristics of cricket batting helmets

To determine whether the helmets currently used by cricket batsmen offer sufficient protection against impacts of a cricket ball, the impact absorption characteristics of six helmets were measured using the drop test at an impact velocity equivalent to a cricket ball with a release speed of 160 km·h-1 (44.4 m·s -1 ). An accelerometer transducer attached to a 5.0 kg striker was dropped from a height of 3.14 m onto the batting helmets to measure the impact characteristics at the three different impact sites:right temple, forehead and back of the helmet. These data were further expressed as a percentage above (-) or below (+) the recommended safety standard of 300 g . The results indicate that the force absorption characteristics of the helmets showed inter- and intra-helmet variations, with 14 of the 18 impact sites (66.7%) assessed meeting the recommended safety standards. Helmets 1, 2 and 4 succeeded in meeting the safety standards at all impact sites; helmets 5 and 6 both failed at the back and forehead, while helmet 3 failed at all impact sites. These differences were due to the structure and composition of the inner protective layer of the helmets. The helmets that succeeded in meeting the standards were made with a moulded polystyrene insert, a heat-formed ethylene vinyl acetate (EVA) insert, or EVA with a relatively high density that allows a minimal amount of movement of the helmet at ball impact.     

The impact absorption characteristics of cricket batting helmets

To determine whether the helmets currently used by cricket batsmen offer sufficient protection against impacts of a cricket ball, the impact absorption characteristics of six helmets were measured using the drop test at an impact velocity equivalent to a cricket ball with a release speed of 160 km x h(-1) (44.4 m x s(-1)). An accelerometer transducer attached to a 5.0 kg striker was dropped from a height of 3.14 m onto the batting helmets to measure the impact characteristics at the three different impact sites: right temple, forehead and back of the helmet. These data were further expressed as a percentage above (-) or below (+) the recommended safety standard of 300 g. The results indicate that the force absorption characteristics of the helmets showed inter- and intra-helmet variations, with 14 of the 18 impact sites (66.7%) assessed meeting the recommended safety standards. Helmets 1, 2 and 4 succeeded in meeting the safety standards at all impact sites; helmets 5 and 6 both failed at the back and forehead, while helmet 3 failed at all impact sites. These differences were due to the structure and composition of the inner protective layer of the helmets. The helmets that succeeded in meeting the standards were made with a moulded polystyrene insert, a heat-formed ethylene vinyl acetate (EVA) insert, or EVA with a relatively high density that allows a minimal amount of movement of the helmet at ball impact.     

The acute effects of resistance exercise on affect,anxiety, and mood – practical implications for designing resistance training programs

ABSTRACT

Research in aerobic exercise has linked the affective responses (pleasure–displeasure) experienced during exercise to future exercise participation. While this is yet to be confirmed in anaerobic activities, it can be inferred that making resistance exercise (RE) more psychologically rewarding is an important consideration. The purpose of this article is to review the acute effects of RE on affect, anxiety, and mood and to draw conclusions on how to maximize feelings of pleasure in an effort to increase rates of participation. This review provides evidence to support lower training volumes performed at low to moderate intensities (50–70% 1RM) with long inter-set rest intervals (90–150 s). Additional recommendations are provided based on physiological and theoretical support, but there is a strong need for more research on the affective experience of RE.     

Contraction force specificity and its relationship to functional performance

Abstract

Best practice for improving strength and power through resistance strength training has been the subject of much research and subsequent conjecture. Much of the conjecture can be attributed to methodological discrepancies. The type of dynamometry used in testing, the training experience of research participants, the specific technique employed in a lift, and the methods of collection and calculation all impact on the final variables of interest. This review examines contraction force specificity by first addressing the methodological issues surrounding our interpretation of the results. Then we address the kinematics and kinetics associated with single and multiple repetitions in relation to the development of strength, power, and functional performance. This discussion provides the delimitations for analysis of subsequent training studies. Finally, recommendations are formulated with the aim of assisting assessment and training practice as well as providing directions for future research. The results of this review suggest that the enhancements in performance resulting from resistance training are context specific in experienced resistance-trained participants. Thus, specific conditioning could be required to achieve improvements in functional performance in this group.     

Benefits of achieving vigorous as well as moderate physical activity recommendations: Evidence from heart rate complexity and cardiac vagal modulation

Abstract

The aim of this study was to examine differences in traditional heart rate variability measurements and heart rate complexity (sample entropy) in young adults grouped by objectively measured achievement of either moderate or both moderate and vigorous physical activity recommendations. Of 168 young adults tested (86 females, 82 males; age 20.5 ± 1.2 years), 119 achieved only recommendations for moderate physical activity (moderate group) and 49 achieved recommendations for both moderate and vigorous physical activity (vigorous group). Analysis of covariance controlling for sex, weekly minutes of moderate physical activity, and percentage of body fat was used to assess between-group differences in heart rate variability and heart rate complexity. Logistic regression analysis was used to determine the group characteristics that best predicted high heart rate complexity and vagal indices of heart rate variability. The majority of the autonomic measures were higher (P < 0.05) in the vigorous group, and regression analysis showed that vigorous physical activity was the only multivariate predictor of higher heart rate complexity and higher heart rate variability. Young adults engaged in regular vigorous physical activity were more than twice as likely to have high heart rate complexity than those involved in predominantly moderate exercise. These findings suggest that vigorous physical activity is more closely associated with high heart rate complexity than moderate physical activity in young adults.     

Impact of a physical education-based behavioural skill training program on cognitive antecedents and exercise and sport behaviour among adolescents: a cluster-randomized controlled trial

ABSTRACT

Background: School-based physical education has been associated with a multitude of potential learning outcomes. Representatives of a public health perspective suggest that promoting physical activity in and outside the context of school is an important endeavour. While the importance of behavioural skill training to improve (motor) learning is well documented in both general and physical education, the promotion of behavioural skills to foster physically active lifestyles constitutes a rather neglected area in physical education research.

Purpose: To examine whether a standardized physical education-based behavioural skill training program has the potential to positively impact on adolescents’ self-reported exercise and sport participation, as well as cognitive antecedents involved in the regulation of exercise and sport behaviour.

Research design: Cluster-randomized controlled trial.

Methods: A sample of 143 secondary school students (50% girls, aged 14–18 years) attending academic high schools in German-speaking Switzerland were assigned class-wise to the intervention (behavioural skill training) and control condition (conventional physical education lessons). Data were assessed prior and after completion of the 7-week intervention program, which was composed of four 20-min lessons and two reflection phases. Exercise and sport behaviour and cognitive antecedents (exercise/sport intention, motivation, implementation intentions, coping planning, self-efficacy) were assessed via self-reports. A multilevel mixed effects linear regression procedure was used to test the main hypotheses. The regression analyses were adjusted for clustering of school classes, and controlled for baseline levels of the outcome measure and potential confounders.

Results: Compared to a control condition, the intervention program resulted in significant improvements with regard to introjected motivation (p?<?.05), coping planning (p?<?.001) and self-efficacy (p?<?.01). The intervention also had a positive impact on adolescents’ self-reported sport/exercise behaviour (p?<?.001). Improvements in exercise/sport intention (p?<?.05), coping planning (p?<?.01), and self-efficacy (p?<?.01) were associated with increased levels of self-reported exercise/sport participation.

Conclusion: Behavioural skill training as part of compulsory physical education has the potential to improve cognitive antecedents of exercise and sport behaviour and to foster adolescents’ exercise and sport participation. Enhancing behavioural skills might be one way in which school physical education can contribute to the creation of more physically active lifestyles among adolescents.     

Visual Search and Biological Motion Perception in Tennis

Purpose

The purposes of this study were to: (a) examine the effect of experience and goal constraints (speed, accuracy) on kicking patterns; (b) determine if effective striking mass was independent of ankle velocity at impact; and (c) determine the accuracy of kicks relative to independent factors.

Method

Twenty participants were recruited to kick at 3 different velocities with and without an accuracy requirement. Multivariate analysis of variance determined if relative timing of joint angular velocities changed during the kick. Chi-square analysis determined if calculated effective mass was independent of ankle velocity at impact. Analysis of variance (ANOVA) was used to examine differences in absolute constant error and variable error according to independent factors.

Results

Results indicated that experience and speed affect absolute timing of joint velocities with no changes in the relative timing of peak joint velocity across independent factors. Chi-square analysis indicated that calculated effective mass is not independent of ankle velocity. ANOVA indicated that experienced performers displayed less variability error than did inexperienced performers.

Conclusion

It was concluded that: (a) Experience, velocity, and accuracy do not affect the relative timing of kicks; (b) kickers trade ankle velocity at impact for greater effective striking mass and ball velocity; and (c) variability in ball placement is affected by experience.     

Exercise Stress Testing Programs in the United States: A 1975 Status Study

Abstract

The purpose of the study was to document the status of exercise stress testing programs in the United States through an analysis of basic program components. A questionnaire was developed and sent to the list of exercise stress testing facilities compiled and published in 1975 by the National Jogging Association. Completed questionnaires were returned by 139 (60%) of the facilities surveyed. The data revealed that: (a) five categories of functional-clinical settings exist; (b) a large majority of programs are located in densely populated areas, were established within the past five years, and rely upon similar funding sources; (c) most of the clients are men over 35 years of age: (d) the YMCAs as a group vary considerably from the other functional settings with respect to certain aspects of program organization; and (e) there are no uniform standards of education and training for professional personnel, except for physicians. It was concluded that the rapid growth and diversity of exercise stress testing services have created a need for increased communication and cooperation among professionals concerning standards relative to procedures, protocols, and personnel.     

Finnish students’ enjoyment and anxiety levels during fitness testing classes

ABSTRACT

Background: Fitness testing is a commonly applied learning and teaching practice implemented in both secondary and elementary school physical education (PE). Many teachers believe that by using a variety of different tests, they are able to provide students with feedback regarding their fitness status, and furthermore, increase students’ willingness to be physically active later in their lives. However, empirical evidence concerning students’ affective responses during fitness testing classes is limited.

Purpose: The primary aim of the study was to investigate whether students’ perceptions of enjoyment and anxiety differed between two different types of fitness testing classes and PE in general. In addition, the measurement invariances over time and between Grade 5 (aged 11–12) and Grade 8 (aged 14–15) groups were determined.

Method: A total sample of 645 Finnish Grade 5 (N?=?328, 50% boys, mean age?=?11.2, SD?=?0.36) and Grade 8 students (N?=?317, 47% boys, mean age?=?14.2, SD?=?0.35) participated in the study. Series of multi-group confirmatory factor analyses were conducted to test the level of measurement invariance between general PE and fitness testing classes, and between age groups. Strict factorial invariance was supported for both enjoyment and anxiety scales allowing for latent mean comparisons. Latent mean differences were studied using z-tests.

Results: Grade 5 students perceived significantly lower levels of enjoyment and cognitive processes and a higher level of somatic anxiety in fitness testing classes compared to general PE. Additionally, for Grade 8 students, levels of enjoyment and cognitive processes were significantly lower and somatic anxiety and worry higher in fitness testing classes than in general PE. Furthermore, enjoyment was significantly higher, and cognitive processes, somatic anxiety and worry lower among Grade 5 students compared with Grade 8 students in both contextual PE and during fitness testing class.

Conclusion: Results of this study indicate that students’ perceptions of enjoyment were lower in fitness testing classes compared to PE in general. Additionally, students perceived lower levels of cognitive anxiety and higher levels of somatic anxiety in fitness testing classes than in general PE. It is noteworthy that students might not significantly dislike fitness testing per se but instead have significantly more positive affects towards PE in general. Generally, practitioners conducting fitness testing lessons are encouraged to embrace different strategies such as fostering basic psychological needs or promoting mastery climate to facilitate enjoyment and diminish anxiety.     

Visually focusing on the far versus the near target during the putting stroke

Abstract

The purpose was to evaluate the traditional method, of visually focusing on the ball, in comparison to focusing on the hole, during the putting stroke. The study design consisted of a pretest, a 4-week practice period, and a posttest. Participants (n = 31, handicap: 18.7 ± 10.4) practised using only one of the two gaze techniques. Testing consisted of having all participants putt using both gaze techniques from both a 1.22 m and a 4 m distance. Five putts were executed for each gaze technique/putt length combination for a total of 20 putts in each testing session per participant. The kinematics of every putting stroke executed during testing (1240 strokes) were captured using a TOMI® system. There was a significant improvement in putting success for both groups following practice (P = 0.001). Practising while visually focusing on the hole, resulted in a statistically significant reduction in putter speed variability in comparison to practising while visually focusing on the ball (P = 0.017). Visually focusing on the hole did not meaningfully (nor statistically) affect the quality of impact as assessed by the variability in face angle, stroke path, and impact spot at the precise moment the putter head contacted the ball.     

Bio-pedagogical self-reflection in PETE: reawakening the ethical conscience and purpose in pedagogy and research

abstract

To date, limited attention has been paid to the relationship of young female Muslims in Western Europe and sport. However as the present review will reveal, this relationship can be described as problematic and therefore needs specific attention. On the one hand, research has indicated that most of these girls have a positive attitude towards sport. While on the other hand, their actual level of sport participation is very low in comparison to other youngsters. It is often stated that this discrepancy is caused by the fact that sport participation is highly restricted by Islamic living rules especially for females. And yet a number of authors have argued that Islam does not obstruct females' sport participation. The present paper attempts to provide more insight in a number of characteristics of the relationship between Islam and the sport participation of Muslim girls who live in Western Europe. Finally, some recommendations for a sport promotion policy and future research directions are formulated.     

The role of subconcussive impacts on sway velocities in Division I men’s lacrosse players

Abstract

Head impacts resulting in a concussion negatively affect the vestibular system, but little is known about the effect of subconcussive impacts on this system. This study’s objective was to determine if subconcussive head impacts sustained over one competitive lacrosse season, effect sway velocity. Healthy Division I male lacrosse players (n = 33; aged 19.52 ± 1.20 years) wore instrumented helmets to track head impact exposures. At the beginning and end of the season the players completed an instrumented Balance Error Scoring System assessment to assess sway velocity. Score differentials were correlated to the head impact exposure data collected via instrumented helmets when averaged within participant. Paired samples t-tests revealed a post-season increase in sway velocity on the double leg stance, firm surface (p = 0.002, d = 0.59); tandem stance, firm surface (p = 0.033, d = 0.39) and double leg, foam surface (p = 0.014, d = 0.45) A significant correlation was found between change in tandem stance, firm surface sway velocities and linear acceleration (p < 0.001, r = 0.65). It appears subconcussive impacts may result in tandem stance balance deficits. Repetitive head impacts may negatively affect sway velocity, even in the absence of a diagnosed concussion injury.     

The Impact of Girls' Interscholastic Sport Participation on Academic Orientation

Abstract

This study was designed to assess the influence of athletics and other extracurricular activities on the academic orientation of female high school students. Senior girls were categorized into groups—labeled athlete-only (comprising students who participated only in athletics as an extracurricular activity), service-only (students who participated in service activities only), athlete-service (students participating in both) and neither (students whose extracurricular activities included neither athletics nor service activities). Categorizations were based on listings from their high school yearbooks. Those taking the ACT college entrance exam (N = 487) were compared on composite and English scores to the other groups, and to national and state averages. Analyses of covariance, controlling for SES and extent of activity involvement revealed that the athlete-only group recorded the lowest average scores, but these could not be attributed to the participation category to which they belonged. Rather, socioeconomic level and extent of activity involvement were factors contributing to most of the differences between groups in which higher SES levels and higher levels of involvement were predictive of higher ACT scores. Moreover, none of the groups' scores were significantly different from national or slate averages. These results refute the notion that involvement only in athletics is detrimental to educational achievements for females, and lead to certain recommendations for longitudinal, multi-measure investigations of academic orientations.     

Queering the Pitch and Coming Out to Play: Lesbians in Physical Education and Sport

Abstract

This paper analyses the social construction of heterosexuality and the existence of heterosexism and homophobia within physical education and sport and the impact that they have had on the participation of women and girls in sport. In order to illustrate some of these issues specific attention is directed towards recent research that has explored both the educative and sporting lives of lesbian physical education teachers in England. Further, the paper focuses on those (few) sporting dykes who have dared to come out to play. In so doing reference is made to the lives of ‘girl jocks’, both in individual and team sports and to those sporting arenas where lesbians have been free(r) to play. The paper concludes by offering strategies to not only reclaim sport but to transform it so that just and equitable participation for all might be realised.