Benjamin Clarsen

Norwegian School of Sport Sciences (NIH) · Department of Sports Medicine

Background: Current methods for injury registration in sports injury epidemiology studies may substantially underestimate the true burden of overuse injuries due to a reliance on time-loss injury definitions. Objective: To develop and validate a new method for the registration of overuse injuries in sports. Methods: A new method, including a n...

Background Little information exists on the illness and injury patterns of athletes preparing for the Olympic and Paralympic Games. Among the possible explanations for the current lack of knowledge are the methodological challenges faced in conducting prospective studies of large, heterogeneous groups of athletes, particularly when overuse injuries...

Deciding when to return to sport after injury is complex and multifactorial-an exercise in risk management. Return to sport decisions are made every day by clinicians, athletes and coaches, ideally in a collaborative way. The purpose of this consensus statement was to present and synthesise current evidence to make recommendations for return to spo...

Athletes participating in elite sports are exposed to high training loads and increasingly saturated competition calendars. Emerging evidence indicates that poor load management is a major risk factor for injury. The International Olympic Committee convened an expert group to review the scientific evidence for the relationship of load (defined broa...

Background Training and game loads are potential risk factors of injury in junior elite ice hockey, but the association of training and game loads to injuries is unknown. Purpose To investigate the association of chronic training and game loads to injury risk in junior male elite ice hockey players. Study Design Cohort study; Level of evidence, 2...

Substantial social inequalities in almost all non-fatal and fatal health outcomes are one of the most consistent and universal epidemiological findings. Therefore, monitoring social inequalities in health is considered a key priority for researchers and policy makers. The Global Burden of Disease Injuries, and Risk Factors Study (GBD) is the most c...

The Coronavirus Disease-19 (COVID-19) pandemic forced the Norwegian male premier league football season to reschedule, reducing the fixture calendar substantially. Previous research has shown that a congested match schedule can affect injury rates in professional football. Therefore, we aimed to investigate whether the Norwegian premier league team...

Background Calculating the disease burden due to injury is complex, as it requires many methodological choices. Until now, an overview of the methodological design choices that have been made in burden of disease (BoD) studies in injury populations is not available. The aim of this systematic literature review was to identify existing injury BoD st...

Background Geographical differences in health outcomes are reported in many countries. Norway has led an active policy aiming for regional balance since the 1970s. Using data from the Global Burden of Disease Study (GBD) 2019, we examined regional differences in development and current state of health across Norwegian counties. Methods Data for li...

Background Geographical differences in health outcomes are reported in many countries. Norway has led an active policy aiming for regional balance since the 1970s. Using data from the Global Burden of Disease Study (GBD) 2019, we examined regional differences in development and current state of health across Norwegian counties. Methods Data for lif...

Introduction Most epidemiological studies in the field of military medicine have been based on data from medical records and registries. The aims of this study were to test a self-reporting injury surveillance system commonly used in sports medicine in a military setting, and to describe the injury pattern among Norwegian army conscripts during a p...

Objectives Determine how to assess the cumulative effect of training load on the risk of injury or health problems in team sports. Methods First, we performed a simulation based on a Norwegian Premier League male football dataset (n players=36). Training load was sampled from daily session rating of perceived exertion (sRPE). Different scenarios o...

Background: Top-level football referees take decisions during strenuous physical activity, and often under great mental pressure. Despite their central role in a football match, little is known about referees' health problems, particularly in female referees. Aim: To investigate the prevalence and burden of health problems in female and male top...

Background: Athletics (also known as track and field) is one of the most popular sports in the world and is the centrepiece of the Summer Olympic Games. Participation in athletics training and competition involves a risk of illness and injury. Purpose: To describe injury and illness in British Olympic track and field athletes over three full tra...

Objectives To examine mental health problems among elite athletes in a student population, compared to the general student population, and to explore the association between weekly hours of training across mental health indicators. Methods Data are from a national study from 2018 of all college and university students in Norway. Participants indic...

Background Little is known about the association between physical fitness and the risk of injury or illness in ice hockey. The least-fit players may be more prone to injury and illness. Purpose To examine the association between preseason fitness level and injury or illness risk among elite ice hockey players during the regular season. Study Desi...

The objective of this study was to examine the effect of a neuromuscular training (NMT) warm-up on the prevalence of overuse lower extremity (LE) injuries in children’s football. Twenty Finnish U11-U14 youth football clubs (n=1409 players; females 280, males 1129; age range 9-14) were randomised into intervention and control groups containing 10 cl...

Background Rhythmic gymnastics (RG) is an Olympic sport that demands high training volume from early age. RG combines elements from ballet, artistic gymnastics and modern dance with manipulation of hand-held apparatus. Most elements require extreme flexibility and strength. Objective We investigated the extent of, and risk factors for, injuries am...

Background The Oslo Sports Trauma Research Center questionnaire on Health problems, recently updated to a second version (OSTRC-H2), has shown a greater ability than a traditional surveillance method to detect athletes with health problems in an adult elite cohort. Moreover, it provides a score that could improve traditional injury severity measure...

Background Little is known about the association between physical fitness and the risk of injury or illness in ice hockey. Objective The aim of this study was to examine the association between pre-season fitness level and injury or illness risk among elite ice hockey players during the subsequent season. Design Prospective cohort study. Setting...

Background Athletics is one of the most popular sports in the world and is the centrepiece of the Summer Olympic Games. Participation in athletics training and competition involves a risk of illness and injury. Objective This paper reports and summarises injury and illness in British Olympic track and field athletes over three full training and co...

Background Top-level football referees make decisions during strenuous physical activity and often under great mental pressure. Despite their central role in a football match, little is known about referees’ health problems, particularly female referees. Objective To investigate the prevalence and burden of health problems in female and male top-l...

Background Little is known about the burden of overuse injuries and illnesses in junior elite ice hockey. Objective The aim of this study was to describe the prevalence and burden of all health problems in junior elite ice hockey in Norway during one school year. Design Prospective cohort study. Setting Elite Sport Academy High Schools in Norway...

Background As previous epidemiological studies in elite ice hockey have focused on acute time-loss injuries, little is known about the burden of overuse injuries and illnesses in ice hockey. Objective The aim of this study was to report the prevalence and burden of all health problems in male senior elite ice hockey during one competitive season....

Background Little is known about the overall health of adolescent distance runners. Objective To describe all health problems (injuries and illnesses) in relation to type, location, incidence, prevalence, time loss, severity, and burden, in competitive adolescent distance runners in England. Design Prospective observational study monitoring all h...

Purpose: To map the current practice of handling missing data in the field of training load and injury risk and to determine how missing data in training load should be handled. Methods: A systematic review of the training load and injury risk literature was performed to determine how missing data are reported and handled. We ran simulations to...

Objective To describe the illness and injury pattern of Norwegian Para athletes over five consecutive Paralympic Summer and Winter Games cycles and to identify which health problems should be targeted in risk management plans with respect to impairment types. Methods We monitored athletes from 12 to 18 months prior to each Game using a weekly onli...

Objective To describe and compare hip and groin strength and function of male ice hockey players over one season in players with and without hip and groin problems in the previous season. Design Prospective cohort study. Setting XXXX male ice hockey. Participants We followed 193 players from 10 teams during the 2017/2018 season. Main outcome me...

Background Little is known about the burden of overuse injuries and illnesses in junior elite ice hockey. Purpose To describe the prevalence and burden of all health problems in junior male elite ice hockey players in Norway during 1 school year. Study Design Descriptive epidemiological study. Methods A total of 206 junior male ice hockey player...

Objectives To determine whether the relationship between training load and injury risk is non-linear and investigate ways of handling non-linearity. Methods We analysed daily training load and injury data from three cohorts: Norwegian elite U-19 football (n=81, 55% male, mean age 17 years (SD 1)), Norwegian Premier League football (n=36, 100% male...

The Coronavirus Disease-19 (COVID-19) pandemic forced the Norwegian male premier league football season to reschedule, reducing the fixture calendar substantially. Previous research has shown that a congested match schedule can affect injury rates in professional football. Therefore, we aimed to investigate whether the Norwegian premier league team...

Background In a recent randomised controlled trial, we found that a commonly used training load management approach was not effective in preventing injuries and illnesses in Norwegian elite youth footballers. Aim To investigate players’ and coaches’ barriers and facilitators to a load management approach to prevent injuries and illnesses and their...

Context: The epidemiological focus on time loss may underestimate the true magnitude of hip and groin problems in male ice hockey players. Objective: To describe the prevalence, incidence and severity of hip and groin problems (time loss and non-time-loss) in Swedish ice hockey players over the course of a season and to explore potential pre-season...

Objective To describe the implementation of a health monitoring programme for Norwegian Paralympic and Olympic candidates over five consecutive Olympic and Paralympic Games cycles (London 2012, Sochi 2014, Rio de Janeiro 2016, PyeongChang 2018 and Tokyo 2020). Methods Athletes were monitored for 12–18 months preparing for the games using a weekly...

In 2020, the IOC released a consensus statement that provides overall guidelines for the recording and reporting of epidemiological data on injury and illness in sport. Some aspects of this statement need to be further specified on a sport-by-sport basis. To extend the IOC consensus statement on methods for recording and reporting of epidemiologica...

Background The continuum of resistance model’s premise is that delayed respondents to a survey are more similar to non-respondents than early respondents are. For decades, survey researchers have applied this model in attempts to evaluate and adjust for non-response bias. Despite a recent resurgence in the model’s popularity, its value has only bee...

To describe all health problems (injuries and illnesses) in relation to type, location, incidence, prevalence, time loss, severity, and burden, in competitive adolescent distance runners in England. Prospective observational study. 136 competitive adolescent distance runners (73 female athletes) self-reported all health problems for 24-weeks betwee...

Objectives: To investigate whether the relationship between the acute:chronic workload ratio (ACWR) and health problems varies when different methodological approaches are used to quantify the relationship. Design: Prospective cohort study. Methods: An online questionnaire was used to collect daily health and training information from 86 elite...

Background: The Oslo Sports Trauma Research Center Questionnaires on Health Problems (OSTRC-H) and Overuse Injury (OSTRC-O) have shown a greater ability to identify athletes with health problems and to estimate the severity of those problems compared with traditional surveillance methods. Despite the numerous language adaptations of these question...

The IOC has proposed standard methods for recording and reporting of data for injury and illness in sport. The IOC consensus statement authors anticipated that sport-specific statements would provide further recommendations. This statement is the tennis-specific extension of the partner IOC statement. The International Tennis Federation Sport Scien...

Background The acute:chronic workload ratio (ACWR) is commonly used to manage training load in sports, particularly to reduce injury risk. However, despite its extensive application as a prevention intervention, the effectiveness of load management using ACWR has never been evaluated in an experimental study. Aim To evaluate the effectiveness of a...

Objectives Rhythmic gymnastics is an Olympic sport that demands high training volume from early age. We investigated the extent of, and risk factors for, injuries among competitive Norwegian rhythmic gymnasts. Methods One hundred and seven of 133 (80.5%) female rhythmic gymnasts (mean age: 14.5 years (SD 1.6), mean body mass index: 18.9 (SD 2.2))...

Epidemiological studies of injury in elite and recreational golfers have lacked consistency in methods and definitions employed and this limits comparison of results across studies. In their sports-generic statement, the Consensus Group recruited by the IOC (2020) called for sport-specific consensus statements. On invitation by International Golf F...

Background The continuum of resistance model’s premise is that delayed respondents to a survey are more similar to non-respondents than early respondents are. For decades, survey researchers have applied this model in attempts to evaluate and adjust for non-response bias. Despite a recent resurgence in the model’s popularity, its value has not been...

Background The continuum of resistance model’s premise is that delayed respondents to a survey are more similar to non-respondents than early respondents are. For decades, survey researchers have applied this model in attempts to evaluate and adjust for non-response bias. Despite a recent resurgence in the model’s popularity, its value has not been...

High quality sports injury research can facilitate sports injury prevention and treatment. There is scope to improve how our field applies best practice methods—methods matter (greatly!). The 1st METHODS MATTER Meeting, held in January 2019 in Copenhagen, Denmark, was the forum for an international group of researchers with expertise in research me...

Synopsis: High-quality sports injury research can facilitate sports injury prevention and treatment. There is scope to improve how our field applies best-practice methods-methods matter (greatly!). The first METHODS MATTER meeting, held in January 2019 in Copenhagen, Denmark, was the forum for an international group of researchers with expertise i...

Background The acute chronic workload ratio (ACWR) is widely used to evaluate the relationship between training load and health problems. However, both ACWR and health problems can be defined in many ways, and how these methodological choices affect the relationship is unclear.Aim To investigate whether different results emerge when different defin...

Injury and illness surveillance, and epidemiological studies, are fundamental elements of concerted efforts to protect the health of the athlete. To encourage consistency in the definitions and methodology used, and to enable data across studies to be compared, research groups have published 11 sport-specific or setting-specific consensus statement...

In 2013, the Oslo Sports Trauma Research Center Overuse Injury Questionnaire (OSTRC-O) was developed to record the magnitude, symptoms and consequences of overuse injuries in sport. Shortly afterwards, a modified version of the OSTRC-O was developed to capture all types of injuries and illnesses—The Oslo Sports Trauma Research Center Questionnaire...

Background Injury and illness surveillance, and epidemiological studies, are fundamental elements of concerted efforts to protect the health of the athlete. To encourage consistency in the definitions and methodology used, and to enable data across studies to be compared, research groups have published 11 sport- or setting-specific consensus statem...

Background As previous epidemiological studies in elite ice hockey have focused on acute time-loss injuries, little is known about the burden of overuse injuries and illnesses in ice hockey. Purpose To report the prevalence and burden of all health problems in male professional ice hockey players in Norway during a single competitive season. Stud...

Background The modern style of goalkeeping in ice hockey is thought to predispose athletes to hip and groin problems. However, little is known about the magnitude of these problems in elite goalkeepers. Purpose To describe the incidence, prevalence, and severity of hip and groin problems in elite ice hockey goalkeepers over the course of a single...

Background Athletes who compete in non-weight-bearing activities such as swimming and cycling are at risk of developing low bone mineral density (BMD). Athletes in long-distance running are at risk of low BMD. Objective (1) To evaluate the bone health in Norwegian male and female national elite road cyclists and middle-distance and long-distance...

Objectives To investigate the prevalence and burden of overuse injuries in children’s football as well as player characteristics and their association with overuse injury risk. Methods This investigation is based on the control arm (10 clubs) of a randomised controlled trial investigating prevention of injuries in youth football. We conducted a pr...

Background Groin injuries represent a considerable problem in male football. Previous groin-specific prevention programmes have not shown a significant reduction in groin injury rates. An exercise programme using the Copenhagen Adduction exercise increases hip adduction strength, a key risk factor for groin injuries. However, its preventive effect...

Aim To record overuse injuries among male junior handball players throughout a handball season. Design Prospective cohort study. Methods Ten Norwegian junior male handball teams (145 players aged 16–18 years) were followed for one 10-month season. All players were sent the Oslo Sports Trauma Research Center Overuse Injury Questionaire every secon...

What’s cutting edge in sports medicine?, Norway, februar 2, 2018, 16:45 – 18:00. Introduction Groin problems are highly prevalent in male football players. Previous groin-specific prevention programs have shown no effect on groin injury rates. However, a single-exercise approach targeting hip adduction strength has not been tested previously. Aim...

Little is known regarding the overall health of youth elite athletes. Our aim was to describe the prevalence and severity of health problems in a cohort of youth elite athletes representing a variety of endurance, team and technical sports. Elite sport athletes (N=260, 16.2 yrs) from different Sport Academy High Schools in Norway, and a group of th...

Background Shoulder injuries are common among handball players and predominantly characterised by overuse characteristics. Reduced total glenohumeral rotation, external rotation weakness and scapular dyskinesis have been identified as risk factors among elite male handball players. Aim To assess whether previously identified risk factors are assoc...

Imagine being able to predict the weather next winter with 100% accuracy. Impossible, right? Yet the belief that we can predict which athletes will get injured based on some form of screening test is not uncommon. The challenge of predicting injury prediction was a prevailing theme at the 2017 IOC World Conference on Prevention of Illness and Injur...

Background/aim We aimed to investigate the magnitude and characteristics of injuries and illnesses in Dutch physical education teacher education (PETE) students. Methods During the first 21 weeks of the academic year, 245 first-year students registered their health problems online using the Oslo Sports Trauma Research Centre (OSTRC) Questionnaire...

Background A thorough knowledge of the epidemiology and severity of injuries and illness in youth female elite sports is lacking due to the methodological challenges involved in recording them. In this study, the prevalence and incidence of injuries and illness are assessed among youth female elite athletes. Instead of solely focusing on time-loss...

Objective The aim of this study was to determine whether there is a difference in the prevalence of tennis injuries between the four most common court surfaces in the Netherlands, including hard court, clay, sand-fill artificial grass and red-sand-fill artificial grass. Natural grass was not included in this study. Methods This was a repeated cros...

Background: The majority of surveillance studies in soccer have used a time-loss injury definition, and many groin problems result from overuse, leading to gradually increasing pain and/or reduced performance without necessarily causing an absence from soccer training or match play. Thus, the magnitude of groin problems in soccer has probably been...

Background A thorough knowledge of the epidemiology of health problems in youth female elite sports is lacking, as most studies define health problems as time loss from participation. Objective To prospective investigate the burden of health problems in young female elite athletes. Design Descriptive epidemiology study. Setting Participants were...

Background The importance of a standardised injury and illness surveillance system in elite sports has recently often been highlighted. The OSTRC Questionnaire on Health Problems was developed and validated at the Oslo Sports Trauma Research Centre in Norway and showed very good validity. Objective The aim of this study was to translate, culturall...

Background Shoulder injuries are common among handball players and are dominated by overuse characteristics. Objective Assess the effect of three previously identified risk factors for shoulder problems (reduced glenohumeral rotation, external rotation weakness and scapula dyskinesis). Design Prospective cohort. Setting Twenty-three handball tea...