The Effect of Play Type and Collision Closing Distance on Head Impact Biomechanics

Football accounts for 55% of concussions to collegiate athletes. In the National Football League, players are at a greater risk for concussion during kickoffs and punts compared to rushing and passing plays. The two primary purposes of this study were to determine if game-related special teams head impacts were greater in magnitude than head impacts sustained during offensive and defensive plays, and to better understand the effect closing distance between players (short vs. long) had on head impact magnitude. Collegiate football players were enrolled in a prospective cohort study assessing head impact biomechanics during special teams, offensive, and defensive collisions; long closing distance (≥10 yards) and short closing distance (<10 yards) impacts were also studied. Data were analyzed using random intercepts general linear mixed models. Long closing distance collisions generated more severe head impacts than short closing distances. Collisions occurring on special teams plays over long closing distances were most severe while collisions occurring on special teams and defensive plays over short closing distances resulted in the least severe impacts. Decreasing the impact severity of collisions in collegiate football may be accomplished by reducing the closing distance prior to impact.     

Head Impact Exposure in Youth Football: High School Ages 14 to 18 Years and Cumulative Impact Analysis

Sports-related concussion is the most common athletic head injury with football having the highest rate among high school athletes. Traditionally, research on the biomechanics of football-related head impact has been focused at the collegiate level. Less research has been performed at the high school level, despite the incidence of concussion among high school football players. The objective of this study is to twofold: to quantify the head impact exposure in high school football, and to develop a cumulative impact analysis method. Head impact exposure was measured by instrumenting the helmets of 40 high school football players with helmet mounted accelerometer arrays to measure linear and rotational acceleration. A total of 16,502 head impacts were collected over the course of the season. Biomechanical data were analyzed by team and by player. The median impact for each player ranged from 15.2 to 27.0 g with an average value of 21.7 (±2.4) g. The 95th percentile impact for each player ranged from 38.8 to 72.9 g with an average value of 56.4 (±10.5) g. Next, an impact exposure metric utilizing concussion injury risk curves was created to quantify cumulative exposure for each participating player over the course of the season. Impacts were weighted according to the associated risk due to linear acceleration and rotational acceleration alone, as well as the combined probability (CP) of injury associated with both. These risks were summed over the course of a season to generate risk weighted cumulative exposure. The impact frequency was found to be greater during games compared to practices with an average number of impacts per session of 15.5 and 9.4, respectively. However, the median cumulative risk weighted exposure based on combined probability was found to be greater for practices vs. games. These data will provide a metric that may be used to better understand the cumulative effects of repetitive head impacts, injury mechanisms, and head impact exposure of athletes in football.     

The Effect of Visual and Sensory Performance on Head Impact Biomechanics in College Football Players

The development of prevention strategies is critical to address the rising prevalence of sport-related concussions. Visual and sensory performance may influence an individual’s ability to interpret environmental cues, anticipate opponents’ actions, and create appropriate motor responses limiting the severity of an impending head impact. The purpose of this study was to determine the relationship between traditional and visual sensory reaction time measures, and the association between visual and sensory performance and head impact severity in college football players. Thirty-eight collegiate football players participated in the study. We used real-time data collection instrumentation to record head impact biomechanics during games and practices. Our findings reveal no significant correlations between reaction time on traditional and visual sensory measures. We found a significant association between head impact severity and level of visual and sensory performance for multiple assessments, with low visual and sensory performers sustaining a higher number of severe head impacts. Our findings reveal a link between level of visual and sensory performance and head impact biomechanics. Future research will allow clinicians to have the most appropriate testing batteries to identify at-risk athletes and create interventions to decrease their risk of injurious head impacts.     

Helmet Fit Assessment and Concussion Risk in Youth Ice Hockey Players: A Nested Case-Control Study

ContextInjury surveillance has shown that concussions are the most common injury in youth ice hockey. Research examining the criteria for ensuring the correct fit of protective equipment and its potential relationship with concussion risk is very limited.ObjectiveTo evaluate the association between helmet fit and the odds of experiencing a concussion among youth ice hockey players.DesignNested case-control within a cohort study.SettingCalgary, Alberta, Canada.Patients or Other ParticipantsData were collected for 72 concussed, 41 nonconcussion-injured, and 62 uninjured ice hockey players aged 11 to 18 years.Main Outcome Measure(s)Helmet-fit assessments were conducted across players and encompassed helmet specifications, condition, certification, and criteria measuring helmet fit. Using a validated injury-surveillance system, we identified participants as players with suspected concussions or physician-diagnosed concussions or both. One control group comprised players who sustained nonconcussion injuries, and a second control group comprised uninjured players. Helmet-fit criteria (maximum score = 16) were assessed for the concussed players and compared with each of the 2 control groups. The primary outcome was dichotomous (>1 helmet-fit criteria missing versus 0 or 1 criterion missing). Logistic and conditional logistic regression were used to investigate the effect of helmet fit on the odds of concussion.ResultsThe primary analysis (54 pairs matched for age, sex, and level of play) suggested that inadequate helmet fit (>1 criterion missing) resulted in greater odds of sustaining a concussion when comparing concussed and uninjured players (odds ratio [OR] = 2.67 [95% CI = 1.04, 6.81], P = .040). However, a secondary unmatched analysis involving all participants indicated no significant association between helmet fit and the odds of sustaining a concussion when we compared concussed players with nonconcussion-injured players (OR = 0.98 [0.43, 2.24], P = .961) or uninjured players (OR = 1.66 [0.90, 3.05], P = .103).ConclusionsInadequate helmet fit may affect the odds of sustaining a concussion in youth ice hockey players. Future investigators should continue to evaluate this relationship in larger samples to inform helmet-fit recommendations.     

Jump-Landing Biomechanics and Knee-Laxity Change Across the Menstrual Cycle in Women With Anterior Cruciate Ligament Reconstruction

Context:

Of the individuals able to return to sport participation after an anterior cruciate ligament(ACL) injury, up to 25% will experience a second ACL injury. This population may be more sensitive to hormonal fluctuations, which may explain this high rate of second injury.

Objective:

To examine changes in 3-dimensional hip and knee kinematics and kinetics during a jump landing and to examine knee laxity across the menstrual cycle in women with histories of unilateral noncontact ACL injury.

Design

 Controlled laboratory study.

Setting:

Laboratory.

Patients or Other Participants:

A total of 20 women (age = 19.6 ± 1.3 years, height = 168.6 ± 5.3 cm, mass = 66.2 ± 9.1 kg) with unilateral, noncontact ACL injuries.

Intervention(s)

Participants completed a jump-landing task and knee-laxity assessment 3 to 5 days after the onset of menses and within 3 days of a positive ovulation test.

Main Outcome Measure(s):

Kinematics in the uninjured limb at initial contact with the ground during a jump landing, peak kinematics and kinetics during the loading phase of landing, anterior knee laxity via the KT-1000, peak vertical ground reaction force, and blood hormone concentrations (estradiol-β-17, progesterone, free testosterone).

Results:

At ovulation, estradiol-β-17 (t = −2.9, P = .009), progesterone (t = −3.4, P = .003), and anterior knee laxity (t = −2.3, P = .03) increased, and participants presented with greater knee-valgus moment (Z = −2.6, P = .01) and femoral internal rotation (t = −2.1, P = .047). However, during the menses test session, participants landed harder (greater peak vertical ground reaction force; t = 2.2, P = .04), with the tibia internally rotated at initial contact (t = 2.8, P = .01) and greater hip internal-rotation moment (Z = −2.4, P = .02). No other changes were observed across the menstrual cycle.

Conclusions

Knee and hip mechanics in both phases of the menstrual cycle represented a greater potential risk of ACL loading. Observed changes in landing mechanics may explain why the risk of second ACL injury is elevated in this population.Key Words: hormones, estrogen, vertical ground reaction force, knee-valgus moment

Key Points

• Clinicians should be aware of the high rate of second injury and biomechanical consequences of many factors related to return to sport participation after anterior cruciate ligament (ACL) injury, including sensitivity to hormonal fluctuations and asymmetrical limb loading.
• The biomechanical profiles of women with ACL injury changed during the preovulatory phase of the menstrual cycle, possibly increasing the risk of second ACL injury.
• Women with ACL reconstructions should have their landing mechanics evaluated before returning to sport participation.
• Anterior knee laxity and jump-landing biomechanics changed across the menstrual cycle in women with unilateral ACL injuries.
• Both menstrual cycle phases had biomechanical variables associated with ACL loading.

The risk of sustaining a noncontact anterior cruciate ligament (ACL) injury is not equal across the menstrual cycle.^1–4 The menstrual cycle consists of the follicular, ovulatory, and luteal phases, which have markedly different hormonal profiles. The follicular phase is associated with the lowest concentrations of estrogen, progesterone, and testosterone. Ovulation, which follows the follicular phase, occurs between days 9 and 20 and is associated with a spike in luteinizing hormone and then a spike in estrogen.⁵ This is the largest concentration of estrogen during the menstrual cycle. The final phase of the menstrual cycle is the luteal phase, which is associated with prolonged elevated estrogen levels. Progesterone also increases substantially during this phase. Researchers^6,7 have reached consensus that the preovulatory phase (from the follicular phase to ovulation) of the menstrual cycle presents the highest risk for noncontact ACL injuries. The risk of injury is thought to result from hormonal fluctuations influencing tissue that, in turn, affects neuromuscular characteristics during dynamic tasks, such as landing from a jump.^8,9 Differences across menstrual cycle phases have been identified in variables believed to be associated with joint stability, including laxity,^5,10,11 muscle stiffness,⁹ strength,^12–14 proprioception,¹⁵ and muscle-activation patterns.¹⁶ However, this area is not without controversy, with other researchers^17–20 observing no change across the menstrual cycle in similar variables.Reproductive hormones seem to influence ACL laxity in females with normal menstrual cycles and physiologic levels of estrogen and progesterone.^5,11,21–25 Numerous authors have concluded that anterior laxity differs between sexes, with males having less laxity than females.^25–31 Again, this area is not without controversy, as several authors have concluded that anterior knee laxity does not change across the menstrual cycle.^18,31–36 However, negative correlations have been observed between ACL stiffness and estrogen concentration in active females, indicating that an increase in estrogen is associated with lower levels of ligament stiffness.²¹ Additionally, evidence^8,37,38 has suggested that ACL laxity may influence muscular response during dynamic activity. Park et al⁸ collected biomechanical data on 26 participants and initially observed no change in kinematic and kinetic variables across the 3 phases of the menstrual cycle. However, when they reorganized participants based on their relative levels of knee laxity into low-, medium-, and high-laxity time points, the authors found that the high-laxity group had a 30% increase in adduction impulse, 20% increase in adduction moment, and 45% increase in external rotation compared with the medium- and low-laxity groups.⁸ This information demonstrates that knee laxity can influence joint loading and potentially influence noncontact ACL injury.Besides knee laxity, other biomechanical factors are associated with ACL loading and ACL injury during jumping and landing. Landing with decreased sagittal-plane motion or moment (knee and hip extension) and increased frontal- and rotational-plane motion of the hip (adduction and internal rotation) and knee (valgus and internal rotation) contribute to ACL loading.³⁹ Researchers^8,40,41 have examined changes in jump-landing mechanics across the menstrual cycle in healthy female populations without histories of ACL injury. These authors observed no change in jump-landing hip and knee mechanics across the menstrual cycle, leading them to conclude that injury rates were most likely due to other factors, including strength or ligament properties.⁴¹ One limitation of these studies is that some women may be more responsive to hormonal fluctuations than others (ie, responders versus nonresponders).^5,11 We theorize that females with histories of ACL injury may be responsive to hormonal fluctuations, and this increased sensitivity may have a greater effect on tissue and ultimately landing mechanics. Additionally, up to 25% of individuals who sustain primary ACL ruptures will have second ACL injuries, with many second injuries occurring in the contralateral limb.^42–44 In a recent paper on second ACL injuries, Paterno et al⁴² examined athletes who were returning to high-level sports and observed that 75% of second ACL injuries occurred in the contralateral limb and 88% of individuals sustaining these injuries were females. The rate of second injury is particularly high for individuals returning to sport participation even after successfully completing rehabilitation programs.⁴⁴ This warrants further investigation because underlying risk factors, such as hormones, could play a role in the rates of second injury in the contralateral limb. Therefore, the purpose of our study was to examine anterior knee laxity and 3-dimensional hip and knee kinematics and kinetics across the menstrual cycle in a population of women with previous unilateral, noncontact ACL injuries. We hypothesized that biomechanical variables assessed during a jump landing would be altered at ovulation in ways that would increase ACL loading and laxity compared with menses. We based this theory on research in which investigators^5,38 have identified increased ligamentous laxity at ovulation. Additionally, we hypothesized that hip and knee kinematics and kinetics during a jump landing would change in ways associated with increased ACL loading.^5,38     

Temporomandibular Joint: Disorders,Treatments, and Biomechanics

Temporomandibular joint (TMJ) is a complex, sensitive, and highly mobile joint. Millions of people suffer from temporomandibular disorders (TMD) in USA alone. The TMD treatment options need to be looked at more fully to assess possible improvement of the available options and introduction of novel techniques. As reconstruction with either partial or total joint prosthesis is the potential treatment option in certain TMD conditions, it is essential to study outcomes of the FDA approved TMJ implants in a controlled comparative manner. Evaluating the kinetics and kinematics of the TMJ enables the understanding of structure and function of normal and diseased TMJ to predict changes due to alterations, and to propose more efficient methods of treatment. Although many researchers have conducted biomechanical analysis of the TMJ, many of the methods have certain limitations. Therefore, a more comprehensive analysis is necessary for better understanding of different movements and resulting forces and stresses in the joint components. This article provides the results of a state-of-the-art investigation of the TMJ anatomy, TMD, treatment options, a review of the FDA approved TMJ prosthetic devices, and the TMJ biomechanics.     

事件影响量表的信度、效度分析

目的：分析和探索事件影响量表(IES)的信度和效度。方法：以跳楼自杀事件后58名现场目击者作为被试，分别在事件后第二周和第四周进行IES的测查，同时由精神科医生根据创伤性应激障碍临床诊断访谈提纲问卷分别进行个别临床诊断性访谈。对获取的数据进行相关分析和因子分析。结果：IES的稳定性、内部一致性和内容效度、及与ASD诊断的准则关联效度均良好。结论：目前，IES是一个比较好的评估创伤性事件应激反应的工具。     

跑姿再训练对冲击力、下肢生物力学及刚度的影响

目的 通过建立12周跑姿再训练（gait retraining,GR）的干预模式（即通过一定的姿态目标改变跑者原有跑姿）,确定GR前后跑步时垂直地面反作用力（vertical ground reaction force, vGRF）以及髋、膝、踝三关节运动学、动力学和下肢刚度特征的变化,探究跑姿转换对冲击力和下肢生物力学的影响。方法 采用Vicon 运动捕捉系统和Kistler三维测力台同步采集30名跑步爱好者（GR组15人,对照组15人）GR前后穿着极简鞋以 12 km/h±5%速度通过测力台的GRF以及标记点轨迹。结果 共17名受试者（GR组9人,对照组8人）完成训练。训练后两组最大负载率都显著下降,GR组相比对照组最大负载率更低;GR组足部触地角度显著减小,两组跖屈角度和髋关节蹬伸角速度都显著增加;GR组踝关节力矩增加;两组下肢刚度均显著增加。结论 成功建立12周GR运动干预模型（前掌着地转化率为78%）。GR能有效避免冲击力峰值、降低最大负载率、提高下肢刚度,进而在减小甚至避免由冲击力引起的跑步损伤风险的同时,为提高跑步经济性提供可能。     

Measuring Head Kinematics in Football: Correlation Between the Head Impact Telemetry System and Hybrid III Headform

Over the last decade, advances in technology have enabled researchers to evaluate concussion biomechanics through measurement of head impacts sustained during play using two primary methods: (1) laboratory reconstruction of open-field head contact, and (2) instrumented helmets. The purpose of this study was to correlate measures of head kinematics recorded by the Head Impact Telemetry (HIT) System (Simbex, NH) with those obtained from a Hybrid III (HIII) anthropometric headform under conditions that mimicked impacts occurring in the NFL. Linear regression analysis was performed to correlate peak linear acceleration, peak rotational acceleration, Gadd Severity Index (GSI), and Head Injury Criterion (HIC₁₅) obtained from the instrumented helmet and HIII. The average absolute location error between instrumented helmet impact location and the direction of HIII head linear acceleration were also calculated. The HIT System overestimated Hybrid III peak linear acceleration by 0.9% and underestimated peak rotational acceleration by 6.1% for impact sites and velocities previously identified by the NFL as occurring during play. Acceleration measures for all impacts were correlated; however, linear was higher (r ² = 0.903) than rotational (r ² = 0.528) primarily due to lower HIT System rotational acceleration estimates at the frontal facemask test site. Severity measures GSI and HIC were also found to be correlated, albeit less than peak linear acceleration, with the overall difference between the two systems being less than 6.1% for either measure. Mean absolute impact location difference between systems was 31.2 ± 46.3° (approximately 0.038 ± 0.050 m), which was less than the diameter of the impactor surface in the test. In instances of severe helmet deflection (2.54–7.62 cm off the head), the instrumented helmet accurately measured impact location but overpredicted all severity metrics recorded by the HIII. Results from this study indicate that measurements from the two methods of study are correlated and provide a link that can be used to better interpret findings from future study using either technology.     

Temporal Effects of Impact on Articular Cartilage Cell Death, Gene Expression, Matrix Biochemistry, and Biomechanics

Articular cartilage injury can cause post-traumatic osteoarthritis, but early processes leading to the disease are not well understood. The objective of this study was to characterize two levels of impact loading at 24 h, 1 week, and 4 weeks in terms of cell death, gene expression, extracellular matrix biochemistry, and tissue biomechanical properties. The data show cell death increased and tissue stiffness decreased by 24 h following High impact (2.8 J). These degradative changes persisted at 1 and 4 weeks, and were further accompanied by measurable changes in ECM biochemistry. Moreover, following High impact at 24 h there were specific changes in gene expression that distinguished injured tissue from adjacent tissue that was not loaded. In contrast, Low impact (1.1 J) showed little change from control specimens at 24 h or 1 week. However, at 4 weeks, a significant increase in cell death and significant decrease in tissue stiffness were present. The constellation of findings indicates Low impacted tissue exhibited a delayed biological response. The study characterizes a model system for examining the biology of articular cartilage post-impact, as well as identifies possible time points and success criteria to be used in future studies employing intervention agents.     

Stents: Biomechanics,Biomaterials, and Insights from Computational Modeling

Coronary stents have revolutionized the treatment of coronary artery disease. Improvement in clinical outcomes requires detailed evaluation of the performance of stent biomechanics and the effectiveness as well as safety of biomaterials aiming at optimization of endovascular devices. Stents need to harmonize the hemodynamic environment and promote beneficial vessel healing processes with decreased thrombogenicity. Stent design variables and expansion properties are critical for vessel scaffolding. Drug-elution from stents, can help inhibit in-stent restenosis, but adds further complexity as drug release kinetics and coating formulations can dominate tissue responses. Biodegradable and bioabsorbable stents go one step further providing complete absorption over time governed by corrosion and erosion mechanisms. The advances in computing power and computational methods have enabled the application of numerical simulations and the in silico evaluation of the performance of stent devices made up of complex alloys and bioerodible materials in a range of dimensions and designs and with the capacity to retain and elute bioactive agents. This review presents the current knowledge on stent biomechanics, stent fatigue as well as drug release and mechanisms governing biodegradability focusing on the insights from computational modeling approaches.     

事件影响量表-修订版(IES-R)在女性犯人中的信度、效度分析

目的:建立事件影响量表-修订版22个条目量表(IES-R)的中文版。方法:439名经过至少1件创伤性事件的女犯人完成了IES-R,分析量表的重测信度和内部一致性、条目间平均相关系数;总分与各因子间的相关系数、内容区分效度,并进行划界分的诊断性评价。结果:IES-R中文版的重测信度为0·86,Cronbach'sα系数为0·96,条目间平均相关系数在0·42~0·60之间。总分与各因子的相关系数在0·84~0·91之间,各因子间的相关系数在0·75~0·89之间,PTSD组的总分明显高于非PTSD组。划界分35时,对PTSD和部分PTSD诊断预测的敏感度为0·86、特异度0·86、诊断效率0·85。结论:IES-R中文版具有良好的信、效度,在我国可以作为一种较好的创伤后应激症状的测评工具。划界分35,量表对PTSD和部分PTSD有一定的预测力。     

Biomechanics of plaque rupture: progress,problems, and new frontiers

Plaque rupture has become identified as a critical step in the evolution of arterial plaques, especially as clinically significant events occur in critical arteries. It has become common in the past dozen years or so to consider which plaques are vulnerable, even though not yet ruptured. Thrombotic events have remained significant, but in a context where they are seen as being triggered often by plaque rupture. Weaving together considerations from structural mechanics, fluid mechanics, plaque morphology, epidemiological pathology, micromechanical measurements of arterial wall tissues, and emerging information on the complex roles of the matrix metalloproteinases, this critical review draws attention to the relative paucity of data (i) on the mechanical behavior of small test portions of arterial tissues and (ii) on the relation of plaque locations to local vessel curvature and curvature flexure. This is especially important in the epicardial arteries, where combination of biplane angiograms and intravascular ultrasound (both becoming increasingly available in digital recordings) offer opportunities for clinical investigation, allied to biomechanics, to an extent previously not possible. Improved imaging and local tissue property assessments provide related opportunities for the carotid bifurcation. The discussion includes a proposal for developing an assessment scale for plaque vulnerability. © 2002 Biomedical Engineering Society. PAC2002: 8719Rr, 8719Xx, 8763Df, 4380Vj, 4380Qf     

事件冲击量表在维稳官兵群体中的信效度

目的：检验事件冲击量表在维稳官兵群体中的信度和效度。方法：采用随机整群抽样法抽取427名维稳军人,对事件冲击量表进行信度和效度检验。结果：量表各个条目与总分相关系数为0．613～0．845（P＜0．01）。探索性因素分析显示,所有因子载荷高于0．4,各条目因子归类与原量表一致。总量表的Cronbach＇s α系数为0．955。验证性因素分析发现,拟合指标χ2／f＝1．956,拟合优度指数、增值拟合指数、比较拟合指数、近似均方根误差分别为0．945、0．932、0．953、0．041。结论：事件冲击量表信度和效度较好,达到了心理测量学标准,能够作为测查应激条件下军人心理应激状况的有效测量工具。     

The Effect of MIPS,Headform Condition,and Impact Orientation on Headform Kinematics Across a Range of Impact Speeds During Oblique Bicycle Helmet Impacts

Annals of Biomedical Engineering - Bicycle helmets are designed to attenuate both the linear and rotational response of the head during an oblique impact. Here we sought to quantify how the...     

Development,Validation, and Application of a Parametric Pediatric Head Finite Element Model for Impact Simulations

In this study, a statistical model of cranium geometry for 0- to 3-month-old children was developed by analyzing 11 CT scans using a combination of principal component analysis and multivariate regression analysis. Radial basis function was used to morph the geometry of a baseline child head finite element (FE) model into models with geometries representing a newborn, a 1.5-month-old, and a 3-month-old infant head. These three FE models were used in a parametric study of near-vertex impact conditions to quantify the sensitivity of different material parameters. Finally, model validation was conducted against peak head accelerations in cadaver tests under different impact conditions, and optimization techniques were used to determine the material properties. The results showed that the statistical model of cranium geometry produced realistic cranium size and shape, suture size, and skull/suture thickness, for 0- to 3-month-old children. The three pediatric head models generated by morphing had mesh quality comparable to the baseline model. The elastic modulus of skull had a greater effect on most head impact response measurements than other parameters. Head geometry was a significant factor affecting the maximal principal stress of the skull (p = 0.002) and maximal principal strain of the suture (p = 0.021) after controlling for the skull material. Compared with the newborn head, the 3-month-old head model produced 6.5% higher peak head acceleration, 64.8% higher maximal principal stress, and 66.3% higher strain in the suture. However, in the skull, the 3-month-old model produced 25.7% lower maximal principal stress and 11.5% lower strain than the newborn head. Material properties of the brain had little effects on head acceleration and strain/stress within the skull and suture. Elastic moduli of the skull, suture, dura, and scalp determined using optimization techniques were within reported literature ranges and produced impact response that closely matched those measured in previous cadaver tests. The method developed in this study made it possible to investigate the age effects from geometry changes on pediatric head impact responses. The parametric study demonstrated that it is important to consider the material properties and geometric variations together when estimating pediatric head responses and predicting head injury risks.     

Specific Activity Types at the Time of Event and Outcomes of Out-of-Hospital Cardiac Arrest: A Nationwide Observational Study

This study aimed to describe the characteristics of out-of-hospital cardiac arrest (OHCA) according to specific activity types at the time of event and to determine the association between activities and outcomes according to activity type at the time of event occurrence of OHCA. A nationwide OHCA cohort database, compiled from January 2008 to December 2010 and consisting of hospital chart reviews and ambulance run sheet data, was used. Activity group was categorized as one of the following types: paid work activity (PWA), sports/leisure/education (SLE), routine life (RL), moving activity (MA), medical care (MC), other specific activity (OSA), and unknown activity. The main outcome was survival to discharge. Multivariate logistic analysis for outcomes was used adjusted for potential risk factors (reference = RL group). Of the 72,256 OHCAs, 44,537 cases were finally analyzed. The activities were RL (63.7%), PWA (3.1%), SLE (2.7%), MA (2.0%), MC (4.3%), OSA (2.2%), and unknown (21.9%). Survival to discharge rate for total patients was 3.5%. For survival to discharge, the adjusted odds ratios (95% confidence intervals) were 1.42 (1.06-1.90) in the SLE group and 1.62 (1.22-2.15) in PWA group compared with RL group. In conclusion, the SLE and PWA groups show higher survival to discharge rates than the routine life activity group.