Thor Andersen - Academia.edu (original) (raw)

Papers by Thor Andersen

Research paper thumbnail of Fagfellevurdert artikkel i internasjonalt vitenskapelig tidsskrift

Junge, A; Engebretsen, Lars; Alonso, J.M.; Renström, P.; Mountjoy, M.; Aubry, M.; Dvorak, J. Inju... more Junge, A; Engebretsen, Lars; Alonso, J.M.; Renström, P.; Mountjoy, M.; Aubry, M.; Dvorak, J. Injury surveillance in multi-sport events: the International Olympic Committee approach. British Journal of Sports Medicine. 42, (6): 413-421. 2008. ISSN 0306-3674. Løken, Sverre; Jakobsen, Rune B.; Årøen, Asbjørn; Heir, Stig; Shahdadfar, A; Brinchmann, J.E.; Engebretsen, Lars; Reinholt, Finn Bone marrow mesenchymal stem cells in a hyaluronan scaffold for treatment of an osteochondral defect in a rabbit model. Knee Surgery, Sports Traumatology, Arthroscopy. 16, (10): 896 -903. 2008. ISSN 0942-2056. Moksnes, Håvard; Engebretsen, Lars; Risberg, May Arna Performance-based functional outcome for children 12 years or younger following anterior cruciate ligament injury: a two to nine-year follow-up study. Knee Surgery, Sports Traumatology, Arthroscopy. 16, (3): Increased mast cell numbers in human patellar tendinosis: correlation with symptom duration and vascular hyperplasia. British Journal of Sports Medicine. 42, (9): Self-reported injury history and lower limb function as risk factors for injuries in female youth soccer. American Journal of Sports Medicine. 36, (4): 700 -708. 2008. ISSN 0363-5465.

Research paper thumbnail of Three distinct mechanisms predominate in non-contact anterior cruciate ligament injuries in male professional football players: a systematic video analysis of 39 cases

British journal of sports medicine, Jan 23, 2015

Current knowledge on anterior cruciate ligament (ACL) injury mechanisms in male football players ... more Current knowledge on anterior cruciate ligament (ACL) injury mechanisms in male football players is limited. To describe ACL injury mechanisms in male professional football players using systematic video analysis. We assessed videos from 39 complete ACL tears recorded via prospective professional football injury surveillance between 2001 and 2011. Five analysts independently reviewed all videos to estimate the time of initial foot contact with the ground and the time of ACL tear. We then analysed all videos according to a structured format describing the injury circumstances and lower limb joint biomechanics. Twenty-five injuries were non-contact, eight indirect contact and six direct contact injuries. We identified three main categories of non-contact and indirect contact injury situations: (1) pressing (n=11), (2) re-gaining balance after kicking (n=5) and (3) landing after heading (n=5). The fourth main injury situation was direct contact with the injured leg or knee (n=6). Knee ...

Research paper thumbnail of No association between surface shifts and time-loss overuse injury risk in male professional football

Journal of Science and Medicine in Sport, 2015

To investigate frequent surface shifts and match play on an unaccustomed surface as potential ris... more To investigate frequent surface shifts and match play on an unaccustomed surface as potential risk factors for injury in Scandinavian male professional football. Prospective cohort study. Thirty two top-division clubs (16 Swedish, 16 Norwegian) were followed during seasons 2010 and 2011. The influence from (1) number of surface shifts (between artificial turf and grass) during five-match sequences, and (2) match play on an unaccustomed surface (other surface than on the home venue) on subsequent overuse injury risk was evaluated with generalized estimating equations (GEE). GEE results are presented with risk ratios and 95% confidence interval (CI). Injury rate was expressed as time loss injuries/1000h, and compared between groups with a rate ratio and 95% CI. No association was found between the number of surface shifts and subsequent overuse injury risk (risk ratio 1.01, 95% CI 0.91-1.12). Furthermore, no difference was seen in subsequent overuse injury risk after match play on unaccustomed compared with accustomed surface (risk ratio 1.04, 95% CI 0.78-1.38). Grass clubs (grass installed at home venue) had a lower match injury rate when playing away matches on artificial turf compared with away matches on grass (rate ratio 0.66, 95% CI 0.40-0.89). This study showed no association between surface shifts or playing matches on an unaccustomed surface and time-loss injury risk in professional football, suggesting that clubs and players can cope with such surface transitions.

Research paper thumbnail of Injury prevention strategies at the FIFA 2014 World Cup: perceptions and practices of the physicians from the 32 participating national teams

British journal of sports medicine, 2015

The available scientific research regarding injury prevention practices in international football... more The available scientific research regarding injury prevention practices in international football is sparse. The purpose of this study was to quantify current practice with regard to (1) injury prevention of top-level footballers competing in an international tournament, and (2) determine the main challenges and issues faced by practitioners in these national teams. A survey was administered to physicians of the 32 competing national teams at the FIFA 2014 World Cup. The survey included 4 sections regarding perceptions and practices concerning non-contact injuries: (1) risk factors, (2) screening tests and monitoring tools, (3) preventative strategies and (4) reflection on their experience at the World Cup. Following responses from all teams (100%), the present study revealed the most important intrinsic (previous injury, accumulated fatigue, agonist:antagonist muscle imbalance) and extrinsic (reduced recovery time, training load prior to and during World Cup, congested fixtures) ri...

Research paper thumbnail of Cardiovascular pre-participation screening does not distress professional football players

Background: It has been debated whether cardiovascular screening of athletes creates negative psy... more Background: It has been debated whether cardiovascular screening of athletes creates negative psychological reactions in those being screened. Neither the athletes' level of distress towards, nor their opinion about screening has actually been examined. Therefore, the aim of this study was to assess the level of distress among Norwegian elite male football players and their experiences of screening. Methods: After screening, players completed a 10-item scale assessing their experience on a Likert scale. Their level of distress was measured with the intrusion sub-scale of Impact of Event Scale (IES) (7 items) on a six-point scale (grade 0-5). A sum score of !19 indicates a clinical stress problem. Twenty-five out of 28 teams, 441 of 591 players (75%, mean age 26 [18-39] years) consented to participate. Results: Sixty-four percent felt more confident when playing football and 88% were satisfied having completed the screening. The majority (77%) felt a need for the screening and 84% would strongly recommend it to others. Sixteen percent were afraid that the screening result might have consequences for their own health, and 13% were afraid of losing their license to play football. Less than 3% experienced distress (IES ! 19). Conclusions: The majority of the players were satisfied having completed the screening, felt more confident and would recommend it to other players. Only a marginal proportion of the players were distressed by the screening, but were at least as likely to recommend it.

Research paper thumbnail of young female football players Risk of injury on artificial turf and natural grass in

Research paper thumbnail of Prevention of hamstring strains in elite soccer: an intervention study

Scandinavian Journal of Medicine & Science in Sports, 2007

The purpose was to test the effect of eccentric strength training and flexibility training on the... more The purpose was to test the effect of eccentric strength training and flexibility training on the incidence of hamstring strains in soccer. Hamstring strains and player exposure were registered prospectively during four consecutive soccer seasons (1999)(2000)(2001)(2002) for 17-30 elite soccer teams from Iceland and Norway. The first two seasons were used as baseline, while intervention programs consisting of warm-up stretching, flexibility and/or eccentric strength training were introduced during the 2001 and 2002 seasons. During the intervention seasons, 48% of the teams selected to use the intervention programs. There was no difference in the incidence of hamstring strains between teams that used the flexibility training program and those who did not [relative risk (RR) 5 1.53, P 5 0.22], nor was there a difference compared with the baseline data (RR 5 0.89, P 5 0.75). The incidence of hamstring strains was lower in teams who used the eccentric training program compared with teams that did not use the program (RR 5 0.43, P 5 0.01), as well as compared with baseline data for the same intervention teams (RR 5 0.42, P 5 0.009). Eccentric strength training with Nordic hamstring lowers combined with warm-up stretching appears to reduce the risk of hamstring strains, while no effect was detected from flexibility training alone. These results should be verified in randomized clinical trials.

Research paper thumbnail of Injury surveillance in male professional football; is medical staff reporting complete and accurate?

Scandinavian Journal of Medicine & Science in Sports, 2011

Since the 2000 season, an injury surveillance system has been established to monitor injury risk ... more Since the 2000 season, an injury surveillance system has been established to monitor injury risk and injury patterns in the Norwegian professional football league. The aim of this study was to assess the accuracy of routine injury registration performed by medical staff in professional football. The team medical staff completed injury registration forms on a monthly basis throughout the 2007 season (January-October). Players were interviewed at the end of the season (October/November) about all injuries that occurred from July through September. Thirteen of fourteen teams, 296 of 310 A-squad players were interviewed. An injury was recorded when a player was unable to take fully part in football training or match the day after injury. A total of 174 injuries were registered, 123 acute injuries and 51 overuse injuries. Of these, 141 were reported by medical staff and 122 by players. Eighty-nine injuries (51%) were registered using both methods, 52 (30%) by medical staff only and 33 (19%) by player interviews only. Prospective injury surveillance by team medical staff in Norwegian male professional football underestimates the incidence of time-loss injuries by at least one-fifth.

Research paper thumbnail of A novel partial modification at C2501 in Escherichia coli 23S ribosomal RNA

RNA, 2004

Escherichia coli is the best-characterized organism with respect to posttranscriptional modificat... more Escherichia coli is the best-characterized organism with respect to posttranscriptional modifications of its ribosomal RNA (rRNA). It is presently believed that all the modified nucleotides have been identified, primarily on the basis of two detection methods; modification-induced inhibition of the enzyme reverse transcriptase or analysis by combined HPLC and electrospray ionization mass spectrometry. Comparison of data from these different approaches reveals a disagreement regarding modification of C2501 in E. coli 23S rRNA. A. Bakin and J. Ofengand previously reported the detection of a modification at this site based on a reverse transcriptase assay. J.A. McCloskey and coworkers could not confirm the existence of such a modification using an electrospray ionization mass spectrometry approach. C2501 is therefore generally considered unmodified. We have used a strategy involving isolation of a specific rRNA fragment from E. coli 23S rRNA followed by Matrix Assisted Laser Desorption/Ionization mass spectrometry and tandem mass spectrometry to investigate this controversy. Our data reveal a novel 16-Da partial modification at C2501. We believe that the data reported here clarify the above discrepancy, because a minor partial modification detected in a reverse transcriptase assay would not necessarily be detected by the original mass spectrometry approach. The level of modification was furthermore monitored in different growth situations, and we found a significant positive regulation in stationary phase cells. C2501 is universally conserved and implicated in structure folds very close to the catalytic center of the ribosome. Moreover, several antibiotics bind to nucleotides in this region, which altogether make a modification at this site interesting.

Research paper thumbnail of MINOR HEAD TRAUMA IN SOCCER AND SERUM LEVELS OF S100B

Neurosurgery, 2008

To compare the serum levels of S100B after head trauma with the effect of heading, high-intensity... more To compare the serum levels of S100B after head trauma with the effect of heading, high-intensity exercise, and playing in a league match. Heading and head trauma in soccer have been suspected to cause brain impairment. The protein S100B is a marker of acute neuronal tissue damage. METHODS: Baseline S100B was measured in 535 Norwegian professional soccer players. Two hundred twenty-eight head impacts were registered from 352 league matches. Three teams (n ϭ 48) performed a high-intensity exercise session without heading and a low-intensity session with heading exercises. A blood sample was drawn from each participant within 1 hour (B1) after the session, and another sample (B12) was drawn after a match or training session. The players were assigned to four groups: Head Impact (n ϭ 65), Match Control (match participants without head impact, n ϭ 49), Highintensity Exercise (n ϭ 35), and Heading (n ϭ 36). RESULTS: Serum S100B increased from baseline to B1 for all groups. The increase for the match groups (Head Impact and Match Control) was significantly higher than for both training groups. However, no significant differences between the Head Impact and Match Control groups or between the two training groups were found. A total of 39 players (33.9%) had elevated B1 values (Ն0.12 ng/ml) after a match, but these findings were equally distributed between the Match Control and Head Impact groups. CONCLUSION: Both soccer training and soccer matches cause a transient increase in S100B. There is a possible additive effect of activity with high intensity and heading, but minor head impacts do not seem to cause an additional increase.

Research paper thumbnail of DO MINOR HEAD IMPACTS IN SOCCER CAUSE CONCUSSIVE INJURY? A PROSPECTIVE CASE-CONTROL STUDY

Neurosurgery, 2009

Our objective was to determine whether minor head trauma in elite soccer matches causes measurabl... more Our objective was to determine whether minor head trauma in elite soccer matches causes measurable impairment in brain function. Baseline neuropsychological testing was completed by professional soccer players in the Norwegian elite league, Tippeligaen, before the 2004 and 2005 seasons (n = 462). A player who experienced a head impact during a league match completed a follow-up test the next day (head impact group). Videotapes of all impacts were collected and reviewed. A group of players without head impacts was also tested after a league match to serve as controls (matched control group; n = 47). A total of 228 impacts were identified, and 44 (19.3%) of these were followed up with a CogSport test (CogState, Ltd., Charlton South, Australia; the players who were tested tended to have more severe injuries, but there were only 6 cases with loss of consciousness). The head impact group had a greater change in reaction time from baseline to follow-up compared with the matched control group with regard to the 3 simplest tasks. The largest deficits were seen among the players reporting acute symptoms after the impact, but deficits were also demonstrated among asymptomatic players. Players who experienced 1 or more head impacts during the 2004 season showed a reduction in neuropsychological performance when tested before the 2005 season. However, none of these players was impaired when compared with the test manufacturer's normative data. A reduced neuropsychological performance was found after minor head impacts in soccer, even in allegedly asymptomatic players. However, the long-term cognitive consequences are uncertain.

Research paper thumbnail of ECSS Position Statement 2009: Prevention of acute sports injuries

European Journal of Sport Science, 2010

To maximize the health benefits of sports and exercise and to minimize the direct and indirect co... more To maximize the health benefits of sports and exercise and to minimize the direct and indirect costs associated with injuries, developing and adopting injury prevention strategies is an important goal. The aim of this ECSS consensus paper on injury prevention is to review current evidence on injury prevention methods and training programmes aimed at reducing the most common or severe types of acute injuries. The target audience is everyone involved in protecting the health of the athlete, including coaches, referees, medical staff, sports governing bodies, as well as athletes themselves. Effective sports injury prevention requires successful implementation of efficacious interventions. This paper reviews the main mechanisms and risk factors for acute injuries to the head, shoulder, elbow, hand/wrist, groin, thigh, knee, and ankle, as well as the evidence supporting various strategies to prevent them. Approaches that have been shown to be successful include: (1) using equipment designed to reduce injury risk, (2) adopting the rules of play, and (3) specific exercise programmes developed to reduce injury risk. Sports organizations should adopt available injury prevention strategies as part of their policies.

Research paper thumbnail of Risk of injury in norwegian male professional football

British Journal of Sports Medicine, 2011

BackgroundOnly one previous injury surveillance study (Ekstrand et al., 2010) has been carried ou... more BackgroundOnly one previous injury surveillance study (Ekstrand et al., 2010) has been carried out for several seasons. Ekstrand et al. (2010) found that the injury incidence and pattern were stable during seven Champions League seasons.ObjectiveTo monitor trends in injury incidence and pattern in Norwegian male professional football over six seasons.DesignProspective cohort study where injuries and exposure were registered by team medical staff using the league injury surveillance system for six seasons (2002–2007). An injury was recorded when a player was unable to fully take part in football training or match play.SettingTippeligaen, the top 14 male Norwegian professional teams.Main outcome measurementInjury incidence (injuries/1000 player-hours).ResultsA total of 2365 injuries were recorded; 1664 (70.4%) acute injuries and 701 (29.6%) overuse injuries. The overall incidence of acute injuries was 16.1 per 1000 match hours (95% CI 15.1 to 17.1) and 1.9 (95% CI 1.7 to 2.0) per 1000 h of football training. The incidence of overuse injuries was 1.4 (95% CI 1.3 to 1.5).The incidence of overuse injuries and acute training injuries was consistent during the six-year study period. However, the risk of acute match injury increased (p=0.004). We could not detect any shifts in injury type, location, severity or re-injuries. No significant difference in the risk of acute match injuries (rate ratio (RR): 0.92, 95% CI 0.78 to 1.08), acute training injuries (RR: 1.16, 95% CI 0.99 to 1.36) or overuse injuries (RR: 1.07, 95% CI 0.91 to 1.25) was observed between preseason (January-March) and competitive season (April-October).ConclusionThe risk of acute match injuries in Norwegian male professional football increased during the six-season study period. However, we detected no change in the risk of training or overuse injuries or any difference between the preseason and competitive season.

Research paper thumbnail of Lower incidence of arm-to-head contact incidents with stricter interpretation of the Laws of the Game in Norwegian male professional football

British Journal of Sports Medicine, 2013

Video analyses reveal that the rate of incidents with a propensity for injury caused by opponent-... more Video analyses reveal that the rate of incidents with a propensity for injury caused by opponent-to-player contact has increased by about 50% from 2000 to 2010 in Norwegian male professional football. The aim of the study was to assess whether a stricter interpretation of the Laws of the Game (red cards for high elbows in heading duels and for late/two foot tackles) could reduce the potential for injuries in Norwegian male professional football. A preintervention/postintervention design was employed, where the rate of incidents and injuries from the 2010 season (pre) was compared to the 2011 season (post). An incident was recorded if the match was interrupted by the referee, and the player lay down for more than 15 s, and appeared to be in pain or received medical treatment. Time-loss injuries were recorded by the medical staff of each club. A total of 1421 contact incidents were identified, corresponding to a rate of 92.7 (95% CI 86.0 to 99.4) in the 2010 season and 86.6 (95% CI 80.3 to 99.4) in the 2011 season, with no difference between the two season. We found a reduction in the incidence of total head incidents (rate ratio (RR) 0.81, 95% CI 0.67 to 0.99), and head-incidents caused by arm-to-head contact (RR 0.72, 95% CI 0.54 to 0.97). We found no difference in tackling characteristics or contact injury rate. We found no significant differences in the overall rate of incidents after the introduction of stricter rule enforcement. However, the rate of head and arm-to head incidents was lower in the 2011 season.

Research paper thumbnail of High ambulatory blood pressure in male professional football players

British Journal of Sports Medicine, 2013

Background No data exist on ambulatory blood pressure (ABP) in athletes. Objectives To identify A... more Background No data exist on ambulatory blood pressure (ABP) in athletes. Objectives To identify ABP and examine recommended follow-up of high office blood pressure (OBP) in male professional football players and secondary study indicators of sympathetic activity. Methods Players with high OBP (cases) from a previous screening of 594 players (n=28) were matched for age and ethnicity with players with optimal OBP (controls). High ABP was defined as a mean of ≥135/85 mm Hg during daytime and ≥120/75 mm Hg during night-time. The players replied to questions regarding follow-up of high OBP. High night-time ABP and lack of nocturnal dip (≤10% decline in average BP) were taken as indicators of increased sympathetic activity.

Research paper thumbnail of Text messaging as a new method for injury registration in sports - a methodological study in elite female football

British Journal of Sports Medicine, 2011

Methodological differences in epidemiologic studies have led to significant discrepancies in inju... more Methodological differences in epidemiologic studies have led to significant discrepancies in injury incidences reported. The aim of this study was to evaluate text messaging as a new method for injury registration in elite female football players and to compare this method with routine medical staff registration. Twelve teams comprising 228 players prospectively recorded injuries and exposure through one competitive football season. Players reported individually by answering three text messages once a week. A designated member of the medical staff conducted concurrent registrations of injuries and exposure. Injuries and exposure were compared between medical staff registrations from nine teams and their 159 affiliated players. During the football season, a total of 232 time-loss injuries were recorded. Of these, 62% were captured through individual registration only, 10% by the medical staff only, and 28% were reported through both methods. The incidence of training injuries was 3.7 per 1000 player hours when calculated from individual registration vs 2.2 from medical staff registration [rate ratio (RR): 1.7, 1.2-2.4]. For match injuries, the corresponding incidences were 18.6 vs 5.4 (RR: 3.4, 2.4-4.9), respectively. There was moderate agreement for severity classifications in injury cases reported by both methods (kappa correlation coefficient: 0.48, confidence interval: 0.30-0.66).

Research paper thumbnail of Injury risk for goalkeepers in norwegian male professional football

British Journal of Sports Medicine, 2011

ABSTRACT Background The role of goalkeepers differs considerably from that of outfield players, b... more ABSTRACT Background The role of goalkeepers differs considerably from that of outfield players, but there are no previous studies specifically investigating their injury risk. Objective To investigate injury patterns, identify high-risk situations and describe injury mechanism for goalies. Design Prospective cohort study. Participants 12 male goalkeepers from five of 14 teams in the Norwegian male professional league. Methods Injury information and exposure data were collected for one competitive season, from April until mid-November 2008. Video recordings from 178 of 182 matches were analyzed to identify high-risk injury situations and to describe injury mechanisms. Results A total of 43 injuries were registered. The injury incidence was 27.9 per 1000 playing hours (95% CI 25.8 to 30.4) during matches, 23.6 (21.2 to 26.7) for specific goalkeeper training and 9.1 (8.3 to 10.1) during other football training (RR: 2.6, 95% CI 1.2 to 5.3 specific goalkeeper training compared to football training). Injuries to the upper extremities accounted for 36% of all injuries. The most frequent overuse injury location was the shoulder. Video analysis identified two high-risk situations during matches: 1) Duel in the airspace in front of goal after a cross pass, where the goalkeeper was hit in the stomach/chest by the opponent's shoulder/upper arm. 2) Duel where the goalkeeper collided with the opponent when coming out to save a backroom pass and the goalkeeper was hit in stomach/chest or the knee by the opponent's foot or knee. Video analysis did not reveal any typical mechanism of injury. Conclusion This study provides novel information about injuries and high-risk situations for goalkeepers. Football goalies have higher injury risk during specific goalkeeper training compared to football training. Two high-risk situations for goalkeepers in matches were identified.

Research paper thumbnail of What is more dangerous - football, skiing or snowboarding?

British Journal of Sports Medicine, 2011

BackgroundIt is well known that professional football has a high injury risk. The FIS Injury Surv... more BackgroundIt is well known that professional football has a high injury risk. The FIS Injury Surveillance System increases our knowledge of injuries to elite skiers and snowboarders. But what is more dangerous?ObjectiveTo compare the injury risk in World Cup (WC) skiing and snowboarding with Norwegian professional football (Tippeligaen).Design/SettingWe conducted season-ending interviews with athletes from selected WC-teams in alpine skiing, freestyle

Research paper thumbnail of A simple clinical screening test can identify elite female football players with increased knee valgus angles

British Journal of Sports Medicine, 2011

Research paper thumbnail of Consensus statement on injury definitions and data collection procedures for studies of injuries in rugby union

British Journal of Sports Medicine, 2007

Variations in definitions and methodologies have created differences in the results and conclusio... more Variations in definitions and methodologies have created differences in the results and conclusions obtained from studies of football injuries; this has made inter-study comparisons difficult.

Research paper thumbnail of Fagfellevurdert artikkel i internasjonalt vitenskapelig tidsskrift

Junge, A; Engebretsen, Lars; Alonso, J.M.; Renström, P.; Mountjoy, M.; Aubry, M.; Dvorak, J. Inju... more Junge, A; Engebretsen, Lars; Alonso, J.M.; Renström, P.; Mountjoy, M.; Aubry, M.; Dvorak, J. Injury surveillance in multi-sport events: the International Olympic Committee approach. British Journal of Sports Medicine. 42, (6): 413-421. 2008. ISSN 0306-3674. Løken, Sverre; Jakobsen, Rune B.; Årøen, Asbjørn; Heir, Stig; Shahdadfar, A; Brinchmann, J.E.; Engebretsen, Lars; Reinholt, Finn Bone marrow mesenchymal stem cells in a hyaluronan scaffold for treatment of an osteochondral defect in a rabbit model. Knee Surgery, Sports Traumatology, Arthroscopy. 16, (10): 896 -903. 2008. ISSN 0942-2056. Moksnes, Håvard; Engebretsen, Lars; Risberg, May Arna Performance-based functional outcome for children 12 years or younger following anterior cruciate ligament injury: a two to nine-year follow-up study. Knee Surgery, Sports Traumatology, Arthroscopy. 16, (3): Increased mast cell numbers in human patellar tendinosis: correlation with symptom duration and vascular hyperplasia. British Journal of Sports Medicine. 42, (9): Self-reported injury history and lower limb function as risk factors for injuries in female youth soccer. American Journal of Sports Medicine. 36, (4): 700 -708. 2008. ISSN 0363-5465.

Research paper thumbnail of Three distinct mechanisms predominate in non-contact anterior cruciate ligament injuries in male professional football players: a systematic video analysis of 39 cases

British journal of sports medicine, Jan 23, 2015

Current knowledge on anterior cruciate ligament (ACL) injury mechanisms in male football players ... more Current knowledge on anterior cruciate ligament (ACL) injury mechanisms in male football players is limited. To describe ACL injury mechanisms in male professional football players using systematic video analysis. We assessed videos from 39 complete ACL tears recorded via prospective professional football injury surveillance between 2001 and 2011. Five analysts independently reviewed all videos to estimate the time of initial foot contact with the ground and the time of ACL tear. We then analysed all videos according to a structured format describing the injury circumstances and lower limb joint biomechanics. Twenty-five injuries were non-contact, eight indirect contact and six direct contact injuries. We identified three main categories of non-contact and indirect contact injury situations: (1) pressing (n=11), (2) re-gaining balance after kicking (n=5) and (3) landing after heading (n=5). The fourth main injury situation was direct contact with the injured leg or knee (n=6). Knee ...

Research paper thumbnail of No association between surface shifts and time-loss overuse injury risk in male professional football

Journal of Science and Medicine in Sport, 2015

To investigate frequent surface shifts and match play on an unaccustomed surface as potential ris... more To investigate frequent surface shifts and match play on an unaccustomed surface as potential risk factors for injury in Scandinavian male professional football. Prospective cohort study. Thirty two top-division clubs (16 Swedish, 16 Norwegian) were followed during seasons 2010 and 2011. The influence from (1) number of surface shifts (between artificial turf and grass) during five-match sequences, and (2) match play on an unaccustomed surface (other surface than on the home venue) on subsequent overuse injury risk was evaluated with generalized estimating equations (GEE). GEE results are presented with risk ratios and 95% confidence interval (CI). Injury rate was expressed as time loss injuries/1000h, and compared between groups with a rate ratio and 95% CI. No association was found between the number of surface shifts and subsequent overuse injury risk (risk ratio 1.01, 95% CI 0.91-1.12). Furthermore, no difference was seen in subsequent overuse injury risk after match play on unaccustomed compared with accustomed surface (risk ratio 1.04, 95% CI 0.78-1.38). Grass clubs (grass installed at home venue) had a lower match injury rate when playing away matches on artificial turf compared with away matches on grass (rate ratio 0.66, 95% CI 0.40-0.89). This study showed no association between surface shifts or playing matches on an unaccustomed surface and time-loss injury risk in professional football, suggesting that clubs and players can cope with such surface transitions.

Research paper thumbnail of Injury prevention strategies at the FIFA 2014 World Cup: perceptions and practices of the physicians from the 32 participating national teams

British journal of sports medicine, 2015

The available scientific research regarding injury prevention practices in international football... more The available scientific research regarding injury prevention practices in international football is sparse. The purpose of this study was to quantify current practice with regard to (1) injury prevention of top-level footballers competing in an international tournament, and (2) determine the main challenges and issues faced by practitioners in these national teams. A survey was administered to physicians of the 32 competing national teams at the FIFA 2014 World Cup. The survey included 4 sections regarding perceptions and practices concerning non-contact injuries: (1) risk factors, (2) screening tests and monitoring tools, (3) preventative strategies and (4) reflection on their experience at the World Cup. Following responses from all teams (100%), the present study revealed the most important intrinsic (previous injury, accumulated fatigue, agonist:antagonist muscle imbalance) and extrinsic (reduced recovery time, training load prior to and during World Cup, congested fixtures) ri...

Research paper thumbnail of Cardiovascular pre-participation screening does not distress professional football players

Background: It has been debated whether cardiovascular screening of athletes creates negative psy... more Background: It has been debated whether cardiovascular screening of athletes creates negative psychological reactions in those being screened. Neither the athletes' level of distress towards, nor their opinion about screening has actually been examined. Therefore, the aim of this study was to assess the level of distress among Norwegian elite male football players and their experiences of screening. Methods: After screening, players completed a 10-item scale assessing their experience on a Likert scale. Their level of distress was measured with the intrusion sub-scale of Impact of Event Scale (IES) (7 items) on a six-point scale (grade 0-5). A sum score of !19 indicates a clinical stress problem. Twenty-five out of 28 teams, 441 of 591 players (75%, mean age 26 [18-39] years) consented to participate. Results: Sixty-four percent felt more confident when playing football and 88% were satisfied having completed the screening. The majority (77%) felt a need for the screening and 84% would strongly recommend it to others. Sixteen percent were afraid that the screening result might have consequences for their own health, and 13% were afraid of losing their license to play football. Less than 3% experienced distress (IES ! 19). Conclusions: The majority of the players were satisfied having completed the screening, felt more confident and would recommend it to other players. Only a marginal proportion of the players were distressed by the screening, but were at least as likely to recommend it.

Research paper thumbnail of young female football players Risk of injury on artificial turf and natural grass in

Research paper thumbnail of Prevention of hamstring strains in elite soccer: an intervention study

Scandinavian Journal of Medicine & Science in Sports, 2007

The purpose was to test the effect of eccentric strength training and flexibility training on the... more The purpose was to test the effect of eccentric strength training and flexibility training on the incidence of hamstring strains in soccer. Hamstring strains and player exposure were registered prospectively during four consecutive soccer seasons (1999)(2000)(2001)(2002) for 17-30 elite soccer teams from Iceland and Norway. The first two seasons were used as baseline, while intervention programs consisting of warm-up stretching, flexibility and/or eccentric strength training were introduced during the 2001 and 2002 seasons. During the intervention seasons, 48% of the teams selected to use the intervention programs. There was no difference in the incidence of hamstring strains between teams that used the flexibility training program and those who did not [relative risk (RR) 5 1.53, P 5 0.22], nor was there a difference compared with the baseline data (RR 5 0.89, P 5 0.75). The incidence of hamstring strains was lower in teams who used the eccentric training program compared with teams that did not use the program (RR 5 0.43, P 5 0.01), as well as compared with baseline data for the same intervention teams (RR 5 0.42, P 5 0.009). Eccentric strength training with Nordic hamstring lowers combined with warm-up stretching appears to reduce the risk of hamstring strains, while no effect was detected from flexibility training alone. These results should be verified in randomized clinical trials.

Research paper thumbnail of Injury surveillance in male professional football; is medical staff reporting complete and accurate?

Scandinavian Journal of Medicine & Science in Sports, 2011

Since the 2000 season, an injury surveillance system has been established to monitor injury risk ... more Since the 2000 season, an injury surveillance system has been established to monitor injury risk and injury patterns in the Norwegian professional football league. The aim of this study was to assess the accuracy of routine injury registration performed by medical staff in professional football. The team medical staff completed injury registration forms on a monthly basis throughout the 2007 season (January-October). Players were interviewed at the end of the season (October/November) about all injuries that occurred from July through September. Thirteen of fourteen teams, 296 of 310 A-squad players were interviewed. An injury was recorded when a player was unable to take fully part in football training or match the day after injury. A total of 174 injuries were registered, 123 acute injuries and 51 overuse injuries. Of these, 141 were reported by medical staff and 122 by players. Eighty-nine injuries (51%) were registered using both methods, 52 (30%) by medical staff only and 33 (19%) by player interviews only. Prospective injury surveillance by team medical staff in Norwegian male professional football underestimates the incidence of time-loss injuries by at least one-fifth.

Research paper thumbnail of A novel partial modification at C2501 in Escherichia coli 23S ribosomal RNA

RNA, 2004

Escherichia coli is the best-characterized organism with respect to posttranscriptional modificat... more Escherichia coli is the best-characterized organism with respect to posttranscriptional modifications of its ribosomal RNA (rRNA). It is presently believed that all the modified nucleotides have been identified, primarily on the basis of two detection methods; modification-induced inhibition of the enzyme reverse transcriptase or analysis by combined HPLC and electrospray ionization mass spectrometry. Comparison of data from these different approaches reveals a disagreement regarding modification of C2501 in E. coli 23S rRNA. A. Bakin and J. Ofengand previously reported the detection of a modification at this site based on a reverse transcriptase assay. J.A. McCloskey and coworkers could not confirm the existence of such a modification using an electrospray ionization mass spectrometry approach. C2501 is therefore generally considered unmodified. We have used a strategy involving isolation of a specific rRNA fragment from E. coli 23S rRNA followed by Matrix Assisted Laser Desorption/Ionization mass spectrometry and tandem mass spectrometry to investigate this controversy. Our data reveal a novel 16-Da partial modification at C2501. We believe that the data reported here clarify the above discrepancy, because a minor partial modification detected in a reverse transcriptase assay would not necessarily be detected by the original mass spectrometry approach. The level of modification was furthermore monitored in different growth situations, and we found a significant positive regulation in stationary phase cells. C2501 is universally conserved and implicated in structure folds very close to the catalytic center of the ribosome. Moreover, several antibiotics bind to nucleotides in this region, which altogether make a modification at this site interesting.

Research paper thumbnail of MINOR HEAD TRAUMA IN SOCCER AND SERUM LEVELS OF S100B

Neurosurgery, 2008

To compare the serum levels of S100B after head trauma with the effect of heading, high-intensity... more To compare the serum levels of S100B after head trauma with the effect of heading, high-intensity exercise, and playing in a league match. Heading and head trauma in soccer have been suspected to cause brain impairment. The protein S100B is a marker of acute neuronal tissue damage. METHODS: Baseline S100B was measured in 535 Norwegian professional soccer players. Two hundred twenty-eight head impacts were registered from 352 league matches. Three teams (n ϭ 48) performed a high-intensity exercise session without heading and a low-intensity session with heading exercises. A blood sample was drawn from each participant within 1 hour (B1) after the session, and another sample (B12) was drawn after a match or training session. The players were assigned to four groups: Head Impact (n ϭ 65), Match Control (match participants without head impact, n ϭ 49), Highintensity Exercise (n ϭ 35), and Heading (n ϭ 36). RESULTS: Serum S100B increased from baseline to B1 for all groups. The increase for the match groups (Head Impact and Match Control) was significantly higher than for both training groups. However, no significant differences between the Head Impact and Match Control groups or between the two training groups were found. A total of 39 players (33.9%) had elevated B1 values (Ն0.12 ng/ml) after a match, but these findings were equally distributed between the Match Control and Head Impact groups. CONCLUSION: Both soccer training and soccer matches cause a transient increase in S100B. There is a possible additive effect of activity with high intensity and heading, but minor head impacts do not seem to cause an additional increase.

Research paper thumbnail of DO MINOR HEAD IMPACTS IN SOCCER CAUSE CONCUSSIVE INJURY? A PROSPECTIVE CASE-CONTROL STUDY

Neurosurgery, 2009

Our objective was to determine whether minor head trauma in elite soccer matches causes measurabl... more Our objective was to determine whether minor head trauma in elite soccer matches causes measurable impairment in brain function. Baseline neuropsychological testing was completed by professional soccer players in the Norwegian elite league, Tippeligaen, before the 2004 and 2005 seasons (n = 462). A player who experienced a head impact during a league match completed a follow-up test the next day (head impact group). Videotapes of all impacts were collected and reviewed. A group of players without head impacts was also tested after a league match to serve as controls (matched control group; n = 47). A total of 228 impacts were identified, and 44 (19.3%) of these were followed up with a CogSport test (CogState, Ltd., Charlton South, Australia; the players who were tested tended to have more severe injuries, but there were only 6 cases with loss of consciousness). The head impact group had a greater change in reaction time from baseline to follow-up compared with the matched control group with regard to the 3 simplest tasks. The largest deficits were seen among the players reporting acute symptoms after the impact, but deficits were also demonstrated among asymptomatic players. Players who experienced 1 or more head impacts during the 2004 season showed a reduction in neuropsychological performance when tested before the 2005 season. However, none of these players was impaired when compared with the test manufacturer's normative data. A reduced neuropsychological performance was found after minor head impacts in soccer, even in allegedly asymptomatic players. However, the long-term cognitive consequences are uncertain.

Research paper thumbnail of ECSS Position Statement 2009: Prevention of acute sports injuries

European Journal of Sport Science, 2010

To maximize the health benefits of sports and exercise and to minimize the direct and indirect co... more To maximize the health benefits of sports and exercise and to minimize the direct and indirect costs associated with injuries, developing and adopting injury prevention strategies is an important goal. The aim of this ECSS consensus paper on injury prevention is to review current evidence on injury prevention methods and training programmes aimed at reducing the most common or severe types of acute injuries. The target audience is everyone involved in protecting the health of the athlete, including coaches, referees, medical staff, sports governing bodies, as well as athletes themselves. Effective sports injury prevention requires successful implementation of efficacious interventions. This paper reviews the main mechanisms and risk factors for acute injuries to the head, shoulder, elbow, hand/wrist, groin, thigh, knee, and ankle, as well as the evidence supporting various strategies to prevent them. Approaches that have been shown to be successful include: (1) using equipment designed to reduce injury risk, (2) adopting the rules of play, and (3) specific exercise programmes developed to reduce injury risk. Sports organizations should adopt available injury prevention strategies as part of their policies.

Research paper thumbnail of Risk of injury in norwegian male professional football

British Journal of Sports Medicine, 2011

BackgroundOnly one previous injury surveillance study (Ekstrand et al., 2010) has been carried ou... more BackgroundOnly one previous injury surveillance study (Ekstrand et al., 2010) has been carried out for several seasons. Ekstrand et al. (2010) found that the injury incidence and pattern were stable during seven Champions League seasons.ObjectiveTo monitor trends in injury incidence and pattern in Norwegian male professional football over six seasons.DesignProspective cohort study where injuries and exposure were registered by team medical staff using the league injury surveillance system for six seasons (2002–2007). An injury was recorded when a player was unable to fully take part in football training or match play.SettingTippeligaen, the top 14 male Norwegian professional teams.Main outcome measurementInjury incidence (injuries/1000 player-hours).ResultsA total of 2365 injuries were recorded; 1664 (70.4%) acute injuries and 701 (29.6%) overuse injuries. The overall incidence of acute injuries was 16.1 per 1000 match hours (95% CI 15.1 to 17.1) and 1.9 (95% CI 1.7 to 2.0) per 1000 h of football training. The incidence of overuse injuries was 1.4 (95% CI 1.3 to 1.5).The incidence of overuse injuries and acute training injuries was consistent during the six-year study period. However, the risk of acute match injury increased (p=0.004). We could not detect any shifts in injury type, location, severity or re-injuries. No significant difference in the risk of acute match injuries (rate ratio (RR): 0.92, 95% CI 0.78 to 1.08), acute training injuries (RR: 1.16, 95% CI 0.99 to 1.36) or overuse injuries (RR: 1.07, 95% CI 0.91 to 1.25) was observed between preseason (January-March) and competitive season (April-October).ConclusionThe risk of acute match injuries in Norwegian male professional football increased during the six-season study period. However, we detected no change in the risk of training or overuse injuries or any difference between the preseason and competitive season.

Research paper thumbnail of Lower incidence of arm-to-head contact incidents with stricter interpretation of the Laws of the Game in Norwegian male professional football

British Journal of Sports Medicine, 2013

Video analyses reveal that the rate of incidents with a propensity for injury caused by opponent-... more Video analyses reveal that the rate of incidents with a propensity for injury caused by opponent-to-player contact has increased by about 50% from 2000 to 2010 in Norwegian male professional football. The aim of the study was to assess whether a stricter interpretation of the Laws of the Game (red cards for high elbows in heading duels and for late/two foot tackles) could reduce the potential for injuries in Norwegian male professional football. A preintervention/postintervention design was employed, where the rate of incidents and injuries from the 2010 season (pre) was compared to the 2011 season (post). An incident was recorded if the match was interrupted by the referee, and the player lay down for more than 15 s, and appeared to be in pain or received medical treatment. Time-loss injuries were recorded by the medical staff of each club. A total of 1421 contact incidents were identified, corresponding to a rate of 92.7 (95% CI 86.0 to 99.4) in the 2010 season and 86.6 (95% CI 80.3 to 99.4) in the 2011 season, with no difference between the two season. We found a reduction in the incidence of total head incidents (rate ratio (RR) 0.81, 95% CI 0.67 to 0.99), and head-incidents caused by arm-to-head contact (RR 0.72, 95% CI 0.54 to 0.97). We found no difference in tackling characteristics or contact injury rate. We found no significant differences in the overall rate of incidents after the introduction of stricter rule enforcement. However, the rate of head and arm-to head incidents was lower in the 2011 season.

Research paper thumbnail of High ambulatory blood pressure in male professional football players

British Journal of Sports Medicine, 2013

Background No data exist on ambulatory blood pressure (ABP) in athletes. Objectives To identify A... more Background No data exist on ambulatory blood pressure (ABP) in athletes. Objectives To identify ABP and examine recommended follow-up of high office blood pressure (OBP) in male professional football players and secondary study indicators of sympathetic activity. Methods Players with high OBP (cases) from a previous screening of 594 players (n=28) were matched for age and ethnicity with players with optimal OBP (controls). High ABP was defined as a mean of ≥135/85 mm Hg during daytime and ≥120/75 mm Hg during night-time. The players replied to questions regarding follow-up of high OBP. High night-time ABP and lack of nocturnal dip (≤10% decline in average BP) were taken as indicators of increased sympathetic activity.

Research paper thumbnail of Text messaging as a new method for injury registration in sports - a methodological study in elite female football

British Journal of Sports Medicine, 2011

Methodological differences in epidemiologic studies have led to significant discrepancies in inju... more Methodological differences in epidemiologic studies have led to significant discrepancies in injury incidences reported. The aim of this study was to evaluate text messaging as a new method for injury registration in elite female football players and to compare this method with routine medical staff registration. Twelve teams comprising 228 players prospectively recorded injuries and exposure through one competitive football season. Players reported individually by answering three text messages once a week. A designated member of the medical staff conducted concurrent registrations of injuries and exposure. Injuries and exposure were compared between medical staff registrations from nine teams and their 159 affiliated players. During the football season, a total of 232 time-loss injuries were recorded. Of these, 62% were captured through individual registration only, 10% by the medical staff only, and 28% were reported through both methods. The incidence of training injuries was 3.7 per 1000 player hours when calculated from individual registration vs 2.2 from medical staff registration [rate ratio (RR): 1.7, 1.2-2.4]. For match injuries, the corresponding incidences were 18.6 vs 5.4 (RR: 3.4, 2.4-4.9), respectively. There was moderate agreement for severity classifications in injury cases reported by both methods (kappa correlation coefficient: 0.48, confidence interval: 0.30-0.66).

Research paper thumbnail of Injury risk for goalkeepers in norwegian male professional football

British Journal of Sports Medicine, 2011

ABSTRACT Background The role of goalkeepers differs considerably from that of outfield players, b... more ABSTRACT Background The role of goalkeepers differs considerably from that of outfield players, but there are no previous studies specifically investigating their injury risk. Objective To investigate injury patterns, identify high-risk situations and describe injury mechanism for goalies. Design Prospective cohort study. Participants 12 male goalkeepers from five of 14 teams in the Norwegian male professional league. Methods Injury information and exposure data were collected for one competitive season, from April until mid-November 2008. Video recordings from 178 of 182 matches were analyzed to identify high-risk injury situations and to describe injury mechanisms. Results A total of 43 injuries were registered. The injury incidence was 27.9 per 1000 playing hours (95% CI 25.8 to 30.4) during matches, 23.6 (21.2 to 26.7) for specific goalkeeper training and 9.1 (8.3 to 10.1) during other football training (RR: 2.6, 95% CI 1.2 to 5.3 specific goalkeeper training compared to football training). Injuries to the upper extremities accounted for 36% of all injuries. The most frequent overuse injury location was the shoulder. Video analysis identified two high-risk situations during matches: 1) Duel in the airspace in front of goal after a cross pass, where the goalkeeper was hit in the stomach/chest by the opponent's shoulder/upper arm. 2) Duel where the goalkeeper collided with the opponent when coming out to save a backroom pass and the goalkeeper was hit in stomach/chest or the knee by the opponent's foot or knee. Video analysis did not reveal any typical mechanism of injury. Conclusion This study provides novel information about injuries and high-risk situations for goalkeepers. Football goalies have higher injury risk during specific goalkeeper training compared to football training. Two high-risk situations for goalkeepers in matches were identified.

Research paper thumbnail of What is more dangerous - football, skiing or snowboarding?

British Journal of Sports Medicine, 2011

BackgroundIt is well known that professional football has a high injury risk. The FIS Injury Surv... more BackgroundIt is well known that professional football has a high injury risk. The FIS Injury Surveillance System increases our knowledge of injuries to elite skiers and snowboarders. But what is more dangerous?ObjectiveTo compare the injury risk in World Cup (WC) skiing and snowboarding with Norwegian professional football (Tippeligaen).Design/SettingWe conducted season-ending interviews with athletes from selected WC-teams in alpine skiing, freestyle

Research paper thumbnail of A simple clinical screening test can identify elite female football players with increased knee valgus angles

British Journal of Sports Medicine, 2011

Research paper thumbnail of Consensus statement on injury definitions and data collection procedures for studies of injuries in rugby union

British Journal of Sports Medicine, 2007

Variations in definitions and methodologies have created differences in the results and conclusio... more Variations in definitions and methodologies have created differences in the results and conclusions obtained from studies of football injuries; this has made inter-study comparisons difficult.