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1.
The purpose of this study was to investigate the extent to which ice hockey facial protectors can decrease overall head acceleration during blunt impacts, as well as to identify whether attenuation differences exist between visors and cages. Commercial models of three cages and three visors were assessed. Blunt impacts were simulated, permitting the measurement of peak accelerations (PA) within the surrogate headform. Results indicated that face protectors, in combination with helmets, substantially reduced PA during blunt impacts within threshold safety limits (below 300g). In general, cages showed lower PA than visors. Differences between models were also observed during repeated impacts and impact site. In conclusion, this study demonstrates that facial protectors function beyond their role in solely preventing facial injuries, complementing the role of the helmet in attenuating head deceleration during impact. Consequently, the utilisation of facial protectors may reduce the severity and incidence of head injuries.  相似文献   

2.
ABSTRACT

The purpose of this study was to gather information from scientific literature related to all steps of Van Mechelen’s “sequence of prevention” for injuries applied to youth and adult recreational field hockey players. A systematic review was conducted in Medline via Pubmed and in SPORTDiscus via EBSCOhost. Twenty-six original studies were included. Regarding injury incidence (step 1) results showed several overall injury incidence rates (youth: 1.47 per 1,000 Athlete Exposure (AE) time-loss (TL) injury up to 11.32 per 1,000 AE TL ánd non-time loss (NTL) injury, adults: 2.2 NTL injury per 1,000 AE, 15.2 injury per 1,000 hours of sports participation). Considering games and practices, most injuries were sustained in games (youth: 4.9, adults: 7.87 per 1,000 AE). Considering body parts, highest injury incidence rates were found in body parts in the lower extremities (youth: knee injuries in games (0.33 per 1,000 AE), adults: hamstring injuries in pre-season (0.75 per 1,000 AE)) and injuries in the head/face/eye (youth: 0.66 and adults: 0.94 head/face/eye, 0.71 head/face and 0.63 concussion per 1,000 AE). Regarding aetiology (step 2), no studies were found. Regarding the efficacy of available interventions (step 3 and 4), one study was found among youth players, describing a warm-up programme.  相似文献   

3.
Heat transfer variations of bicycle helmets   总被引：1，自引：0，他引：1  
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.  相似文献   

4.
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.  相似文献   

5.
Aerodynamic efficiency is one of the important criteria for racing bicycle helmets, especially in time trial event. The physical characteristics of a bicycle helmet especially its venting geometry, position and number of vents play a crucial role in the aerodynamic efficiency of the helmet. Despite the importance of this, little information on aerodynamic behaviour of racing bicycle helmets is available. In this study, a series of commercially available time trial helmets were investigated in a wind tunnel environment over a range of wind speeds, and yaw and pitch angles to understand their aerodynamic behaviour. In order to obtain as realistic a data as possible, an instrumented mannequin was used in the wind tunnel testing. The experimental findings indicate that the aerodynamic performance of current production time trial helmets varies significantly. The results also show that helmet length as well as vent geometry and vent area have significant effects on aerodynamic drag of a time trial helmet. A time trial helmet having longer length and smooth vents with minimum vent area can reduce aerodynamic drag significantly.  相似文献   

6.
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.  相似文献   

7.
ABSTRACT

Athletes’ energy distribution over a race (e.g. pacing behaviour) varies across different sports. Swimming is a head-to-head sport with unique characteristics, such as propulsion through water, a multitude of swimming stroke types and lane-based racing. The aim of this paper was to review the existing literature on pacing behaviour in swimming. According to PRISMA guidelines, 279 articles were extracted using the PubMed and Web of Science databases. After the exclusion process was conducted, 16 studies remained. The findings of these studies indicate that pacing behaviour is influenced by the race distance and stroke type. Pacing behaviours in swimming and time-trial sports share numerous common characteristics. This commonality can most likely be attributed to the lane-based racing set-up. The low efficiency of swimming resulting from propulsion through the water induces a rapid accumulation of blood lactate, prompting a change in swimmers’ biomechanical characteristics, with the goal of minimising changes in velocity throughout the race. Although the literature on youth swimmers is scarce, youth swimmers demonstrate more variable pacing profiles and have more difficulty in selecting the most beneficial energy distribution.  相似文献   

8.
ABSTRACT

Though the existence of Relative Age Effects (RAEs) has been documented through a multitude of studies spanning various sports and levels of play, application of solutions related to RAEs has been limited. In this review, the strengths and weaknesses of various proposed solutions to RAEs in youth sport are considered. Our objective was to identify, collate, and disseminate a comprehensive list of solutions related to the prevalence of RAEs in youth sport. English language, peer-reviewed articles were searched using the SPORTDiscuss database. Keywords ‘relative age’, ‘relative age effect*’, and sport* were used to locate research articles. The inclusion criteria were the following: (1) publication date between January 1980 and December 2018; (2) solutions were suggested related to RAEs. Sixty-three peer-reviewed publications contained proposed solutions to RAEs. Many solutions have been proposed to address RAEs in sport. Most are theoretical and there has been no attempt to implement them. Future research should test possible proposed solutions to RAEs in sport. However, implementing these solutions has the potential to both positively and negatively affect career and life outcomes for those athletes involved. Therefore, it is important to be cautious in how these possible solutions are tested.  相似文献   

9.
ABSTRACT

This article presents the results of a scoping review of the sport literature (2000–2014) on psychological and social outcomes relevant to youth alcohol and illicit drug use. Prior reviews report that sport is related to increased alcohol use and reduced illicit drug use among youth, yet provide little guidance regarding the mechanisms that can explain this relationship. We reviewed the literature on sport participation and psychological and social outcomes to identify factors that could help explain this link. Psychological and social factors were selected as they play a paramount role in understanding youth alcohol and drug use. Fifty-nine articles were identified and included in the review. The literature generally supported connections between sport and positive psychological and social outcomes, including self-esteem, self-regulation, general life skills, and pro-social behaviour. Yet limitations in the methods and measures limit the ability to draw conclusions from the literature. In addition, the diversity of youth and sport was generally ignored in the literature. This article suggests a number of directions for future research that might improve our understanding of how sport impacts psychological and social outcomes along with alcohol and illicit drug use.  相似文献   

10.
Abstract

Because of increasing numbers of serious sports-related injuries at all levels of participation, the National Operating Committee on Standards for Athletic Equipment (NOCSAE) was formed. Among their activities aimed at improving the safety of sports participation was the development of standards for impact resistance in both new and refinished football helmets. These standards include not only recommendations as to safe levels of resistance to impact but recommendations as to the number of helmets to be tested from each group of helmets undergoing a refinishing process.

In this study the various sources of variability in the testing procedure are examined. These sources include helmet-to-helmet variability, testing variability, and basic measurement error. A careful examination of this variability in the context of the NOCSAE-recommended testing procedures for recertifying helmets reveals an inadequacy in the NOCSAE standard, in that the probability of returning unsafe helmets to the playing field is unacceptably high.  相似文献   

11.
Purpose: Overuse injuries are common in sport, but complete understanding of injury risk factors remains incomplete. Although biomechanical studies frequently examine musculoskeletal injury mechanisms, human movement variability studies aim to better understand neuromotor functioning, with proposed connections between overuse injury mechanisms and changes in motor variability. Method: In a narrative review, we discuss the variability-overuse injury hypothesis, which suggests repeated load application leads to mechanical tissue breakdown and subsequent injury when exceeding the rate of physiological adaptation. Due to the multidisciplinary nature of this hypothesis, we incorporate concepts from motor control, neurophysiology, biomechanics, as well as research design and data analysis. We therefore summarize multiple perspectives while proposing theoretical relationships between movement variability and lower extremity overuse injuries. Results: Experimental data are presented and summarized from published experiments examining interactions between experimental task demands and movement variability in the context of drop landing movements, along with comparisons to previous movement variability studies. Conclusion: We provide a conceptual framework for sports medicine researchers interested in predicting and preventing sports injuries. Under performance conditions with greater task demands, we predict reduced trial-to-trial movement variability that could increase the likelihood of overuse injuries.  相似文献   

12.
Sports mega-events, such as the Olympic and Paralympic Games, have the potential to inspire increases in population physical activity, yet investigations concerning such legacy outcomes have been inconclusive. This may be due to research design limitations or inconsistent leveraging of potential hosting benefits by event organizers. This systematic review aims to identify current knowledge about the capacity of sports mega-events to inspire increases in physical activity participation among adult populations and develop a research agenda to guide future legacy evaluations. Peer-reviewed, English-language studies published on or after the year 2000 were considered. Six academic databases and grey literature sources were searched, and articles were assessed for methodological quality. Reporting followed PRISMA conventions for systematic reviews. Nine studies were selected after quality evaluation, including previous reviews, quantitative and qualitative research. Most studies found no evidence for long-term physical activity outcomes associated with hosting sports mega-events, although limitations and gaps were identified. These included lack of longitudinal or cohort studies, limited differentiation of subpopulations, use of non-validated instruments, and lack of triangulation for qualitative findings. Only one cohort study from Japan identified sustainable and significant physical activity increases resulting from a previous sports mega-event. Considering theory, the commonly cited Demonstration Effect was reportedly an unreliable framework, although the Festival Effect and Social Ecological Model appear more promising for anticipating and explaining legacy effects. With less than two years until the Tokyo 2020 Olympiad, it is appropriate to commence high-quality legacy research drawing on lessons learned from previous studies.  相似文献   

13.
Background:Football is the most practised sport in the world and is associated with the risk of injuries in the players.Some studies have been published that identify injury prevention programs,but there is no review of the full body of evidence on injury prevention programs for use by football coaches.The aim of this article was to carry out a systematic review of published studies on injury prevention programs for adult male footballers,identify points of common understanding and establish recommendations that should be considered in the design of injury prevention strategies.Methods:PubMed and EMBASE databases were used to identify relevant published articles using the following keywords:"soccer"AND"injury"AND"prevention".Results:A total of 2512 studies were identified initially,but only 11 studies met the inclusion criteria,and their outcomes are presented.Results revealed that injury prevention programs in football have focused on strength training,proprioceptive training,multicomponent programs(balance,core stability,and functional strength and mobility),and warm-up programs.Conclusion:Based on results from the studies analyzed,football players can lower the incidence of match and training injuries by participating in dynamic warm-up programs that include preventive exercises before games or during training sessions,and by adding strength,balance,and mobility training to the training sessions.  相似文献   

14.
In volleyball, the dominant shoulder of the athlete undergoes biomechanical and morphological adaptations; however, definitive conclusions about their exact nature, aetiology, purpose and associations with shoulder injury have not been reached. We present a systematic review of the existing literature describing biomechanical adaptations in the dominant shoulders of volleyball players and factors that may predispose to shoulder pain/injury. A thorough literature search via Medline, EMBASE and SCOPUS was conducted for original studies of volleyball players and 15 eligible articles were identified. Assessment of study quality was performed using the STROBE statement. The reviewed literature supports the existence of a glenohumeral internal rotation deficit (GIRD) and a possible (and less pronounced) external rotation gain in the dominant vs. the non-dominant shoulder of volleyball athletes. Unlike other overhead sports, the GIRD in volleyball athletes appears to be anatomical as a response to the repetitive overhead movements and not to be associated with shoulder pain/injury. Additionally, the dominant shoulder exhibits muscular imbalance, which appears to be a significant risk factor for shoulder pain. Strengthening of the external rotators should be used alongside shoulder stretching and joint mobilisations, core strengthening and optimisation of spike technique as part of injury management and prevention programmes.  相似文献   

15.
In professional cricket, where bowlers can bowl balls that reach speeds of up to 160 km h-1, effective head protection is vital. Current head protection equipment typically consists of a helmet with a high impact grade polypropylene shell, a high density EPS liner, and a metal face guard. Most of the weight in existing helmets is attributed to the steel grill used as the face guard. We present a virtual design approach to the development and evaluation of new face guards made from alternative materials. In particular, we investigate a face guard design for cricket made from polycarbonate rather than steel using an explicit dynamic finite element analysis (FEA) approach. The FEA model developed for this purpose incorporates the headform, helmet, polycarbonate face guard and the impacting ball. ABAQUS CAE was used for FEA. HyperMesh and SolidWorks were used to develop the geometric model. This work identifies appropriate modelling and simulation strategies, and key design attributes for the development of new face guards using alternative materials. A preliminary study shows that by using polycarbonates it is possible to reduce the mass of the face guard by 20%, thus contributing to greater comfort of the players without compromising their safety. The key criteria for reduction of ball deceleration by at least 25% at each test site were satisfied, with deceleration reduction values ranging from 44% to 87% from those due to ball impact with the bare head.  相似文献   

16.
Twenty-six bicycle helmets and their associated visors were characterized for radiant heat transfer using a thermal manikin headform in a climate chamber to assess their ability to protect the wearer from heating by the sun. A single configuration for applied radiant flow of 9.3 W was used to assess the roles of the forward and upper vents and the visor. The helmets shielded 50-75% of the radiant heating without a visor and 65-85% with one. Twenty-three visors were shown to result in a relevant reduction of radiant heating of the face (>0.5 W), with 15 reaching approximately 1 W. Heating of the visor and/or helmet and subsequent heating of the air flowing into the helmet was nevertheless found to be a relevant effect in many cases, suggesting that simple measures like reflective upper surfaces could noticeably improve the radiant heat rejection without changing the helmet structure. The forward vents in the helmets that allow the transmission of radiant heat are often important for forced convection, so that minimizing radiant heating geneally reduces the maximization of forced convective heat loss for current helmets.  相似文献   

17.
The impact absorption characteristics of cricket batting helmets   总被引：1，自引：0，他引：1  
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.  相似文献   

18.
To properly assess sports helmet performance, it is important to select impact conditions that yield high peak linear or angular accelerations. This was done by measuring the kinematic response of a Hybrid III headform when impacted with a modified Wayne State University linear impactor with special consideration for impact locations and angles. The 20 impact conditions (five locations and four angles) were then compared to published thresholds to identify the conditions, which were linked to an increased risk of head injury. These conditions were the following: 1A (linear 121.3g; angular 3.84 krad s−2), 2A (linear 102.1g; angular 9.28 krad s−2), 2C (linear 94.4g; angular 8.67 krad s−2), 3A (linear 132.8g; angular 9.38 krad s−2), 4A (linear 92.8g; angular 11.49 krad s−2), 4D (linear 113.3g; angular 12.86 krad s−2), 5A (linear 116.9g; angular 9.01 krad s−2) and 5D (linear 87.5g; angular 8.81 krad s−2). The results presented in this study were specific to the test rig used as well as the tested conditions; however, it is believed that a test protocol using the above impact conditions could identify the ability of sports helmets to reduce risk of head injuries.  相似文献   

19.
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.  相似文献   

20.
该文采用逻辑分析法和文献资料法来进行社会足球青训机构教练员能力因素的研究。社会足球青训机构教练员是足球教练员这个群体中的一个分类,随着草根足球和校园足球在中国的不断发展,社会足球青训机构教练员的数量正在不断增加。现阶段,社会足球青训机构教练员是绝大部分青少年的“足球启蒙教练”,因此对其能力因素的研究十分重要。该文以社会足球青训机构教练员为研究对象,研究了其指导运动训练能力、临场指挥比赛能力、团队管理能力和影响能力的综合因素。通过研究发现社会足球青训机构教练员需要各种能力,但最为重要的是指导运动训练的能力。  相似文献   

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