Sara Christina Dahlen

• Nuri, Sebastian Gautland; Dahlen, Sara Christina; Bjørneboe, John Andreas & Andersen, Thor Einar (2026). Characteristics of match-related head injuries in professional women's football: A prospective cohort study. Journal of Science and Medicine in Sport. ISSN 1440-2440. doi: 10.1016/j.jsams.2026.04.010. Full text in Research Archive
• Peek, Kerry; Ross, Andrew G.; Williamson, Paula R.; Georgieva, Julia; Andersen, Thor Einar & Meyer, Tim [Show all 10 contributors for this article] (2025). Consensus on the descriptors, definitions, and reporting methods for heading in football studies: A Delphi study. PLOS ONE. 20(7). doi: 10.1371/journal.pone.0327189. Full text in Research Archive Show summary

  Heading in football (soccer) is a complex skill involving deliberate head-to-ball contact, which may pose short-, medium-, and long-term risk to player brain health. However, understanding header exposure during matches and training sessions, as well as comparing header incidence between studies is currently challenging given the lack of standardisation in descriptors, definitions, and reporting methods. This Delphi study aimed to establish a consensus on the descriptors, definitions, and reporting methods for heading in football research to improve consistency and quality. The study involved 167 participants from diverse football-related backgrounds including coaches, players, medical personnel, and researchers, with consensus achieved to include 27 descriptors in minimum reporting criteria for heading in football research. An additional 27 descriptors were also defined for inclusion in an expanded framework. The operational definition of a header was standardised as “a head-to-ball contact where the player makes a deliberate movement to redirect the trajectory of the ball using their head.” The consensus framework provides a standardised approach to heading in football research to enhance data quality and comparability across studies. Improved header incidence data quality has the potential to contribute significantly to our understanding of the risks associated with heading in football to inform future research and practice guidelines.

• Dahlen, Sara Christina; Bjørneboe, John Andreas; Sandmo, Stian Kirkerud; Bache-Mathiesen, Lena Kristin & Andersen, Thor Einar (2025). Video analysis of head impacts in top-level female football players: a cohort study. Science and medicine in football. ISSN 2473-3938. doi: 10.1080/24733938.2025.2548209. Full text in Research Archive Show summary

  This study aimed at exploring the exposure of head impacts, i.e. headers and non-headers, in top-level female football players. The study included all teams (n = 10) and players (n = 238) in the Norwegian Women’s Premier League during the 2023 season. Video analysis was used to register headers and non-headers in the 135 matches of the season. Potential head injuries were compared between video signs and medical reports. The header and non-header incidences were estimated per 90 match minutes with 95% confidence intervals (CI). We observed 9364 headers and 233 non-headers in 135 matches. Nine non-headers resulted in a head injury (all concussions), players’ time loss ranging from 5 to 87 days. The highest number of headers performed by a single player in a match was 22. The total number of headers performed during a match varied between 34 and 125. Defenders had an estimated 4.2 (CI = 3.9–4.3), midfielders 2.9 (CI = 2.7–3.0), and forwards 2.6 (CI = 2.5–3.1) headers per match. There was a positive correlation between heading frequency and age. Forwards were the players most exposed to non-headers, with an estimated 0.09 per match. Most non-headers were caused by unintentional head-to-ball contact. We found that defenders had the highest header frequency. Header frequencies varied substantially between players and from match to match. Forwards had the highest risk of non-headers. Nine non-headers resulted in head injuries.

• Peek, Kerry; Aiello, Francesco; Avery, Lewis; Gardner, Tom; Rutherford, Harvey & Massey, Andrew [Show all 10 contributors for this article] (2024). Characteristics of potential head injury situations at the FIFA World Cup Qatar 2022™. Science and medicine in football. ISSN 2473-3938. doi: 10.1080/24733938.2024.2409689. Full text in Research Archive Show summary

  This exploratory video analysis study aimed to review characteristics of potential head injury situations during a men’s professional international football tournament. For 64 matches of the FIFA World Cup Qatar 2022™ FIFA analysts used match footage to record all potential head injury situations. A potential head injury situation was defined as a player staying down for more than 5 s and/or requesting medical attention, and where the body impact location included the player’s head. Characteristics were further recorded for match, player (i.e. player action including aerial duels), medical assessment, and outcome (e.g. substitution). Descriptive statistics are reported as well as Pearson’s Chi-squared test (or Fisher’s exact test) to explore potential head injury situations more likely to result in medical attention. In total, 149 potential head injury situations occurred in 56 matches (mean 2.33/match, range 0–6) involving 117 players. Eight matches resulted in no incidents. Aerial duels were the most frequent match characteristic leading to a potential head injury situation. Injury stoppage with on-pitch medical assessment occurred in 35 of the 149 potential head injury situations (23%), with pitch-side assessment also occurring in 15 situations (10%), resulting in four concussion substitutions. Players were more likely to require medical attention for potential head injuries sustained when the ball was loose (χ2 = 6.88; p = 0.038) when the injured player was jumping (FET p = 0.044) and for head-to-head contact (FET p = ＜0.001). Further exploration of aerial duels during match play which do and do not lead to potential and actual head injuries is recommended.

• Dyer, Bryce; Ahmed, Osman Hassan; Dahlén, Sara; Dalton, Kristin; Derman, Wayne & Donaldson, Amber [Show all 12 contributors for this article] (2024). Evaluation of the SCAT 5 tool in the assessment of concussion in Para athletes: a Delphi study. British Journal of Sports Medicine. ISSN 0306-3674. 58(12), p. 655–664. doi: 10.1136/bjsports-2023-107426. Full text in Research Archive Show summary

  Objectives To investigate if the sport concussion assessment tool version 5 (SCAT5) could be suitable for application to Para athletes with a visual impairment, a spinal cord injury, or a limb deficiency. Methods A 16-member expert panel performed a Delphi technique protocol. The first round encompassed an open-ended questionnaire, with round 2 onwards being composed of a series of closed-ended statements requiring each expert’s opinion using a five-point Likert scale. A predetermined threshold of 66% was used to decide whether agreement had been reached by the panel. Results The Delphi study resulted in a four-round process. After round 1, 92 initial statements were constructed with 91 statements obtaining the targeted level of agreement by round 4. The expert panellist completion rate of the full four-round process was 94%. In the case of athletes with a suspected concussion with either limb deficiencies or spinal cord injuries, the panel agreed that a baseline assessment would be needed on record is ideal before a modified SCAT5 assessment. With respect to visual impairments, it was conceded that some tests were either difficult, infeasible or should be omitted entirely depending on the type of visual impairment. Conclusion It is proposed that the SCAT5 could be conducted on athletes with limb deficiencies or spinal cord injuries with some minor modifications and by establishing a baseline assessment to form a comparison. However, it cannot be recommended for athletes with visual impairment in its current form. Further research is needed to determine how potential concussions could be more effectively evaluated in athletes with different impairments.

• Peek, Kerry; Ross, Andrew; Andersen, Thor Einar; Meyer, Tim; Dahlén, Sara & Georgieva, Julia [Show all 9 contributors for this article] (2024). Heading in football: a systematic review of descriptors, definitions, and reporting methods used in heading incidence studies. Science and medicine in football. ISSN 2473-3938. doi: 10.1080/24733938.2024.2362191. Full text in Research Archive Show summary

  The primary objective of this systematic review was to describe the number and type of heading descriptors used in all published studies which report on heading incidence in football. The secondary objective was to detail the data collection and reporting methods used in the included studies to present heading incidence data. Eligible studies were identified through searches of five electronic databases: Ovid MEDLINE, CINAHL, EMBASE, SPORTDiscus, and Web of Science, using a combination of free-text keywords (inception to 12th September 2023). Manual searching of reference lists and retrieved systematic reviews was also performed. A descriptive overview and synthesis of the results is presented. From 1620 potentially eligible studies, 71 studies were included, with the following key findings: 1) only 61% of studies defined a header with even fewer (23%) providing an operational definition of a header within the methods; 2) important study and player demographic data including year and country were often not reported; 3) reported heading descriptors and their coding options varied greatly; 4) visual identification of headers was essential when inertial measurement units were used to collect heading incidence data; and 5) there was a lack of standardisation in the reporting methods used in heading incidence studies making comparison between studies challenging. To address these findings, the development of a standardised, internationally supported, operational definition of a header and related heading descriptors should be prioritised. Further recommendations include the development of minimum reporting criteria for heading incidence research.

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• Bjørneboe, John Andreas; Dahlén, Sara; Sandmo, Stian Bahr; Bache-Mathiesen, Lena Kristin & Andersen, Thor Einar (2025). Ingen økt risiko for nevrodegenerativ sykdom hos tidligere kvinnelige toppfotballspillere. Idrettsmedisinsk Høstkongress. p. 12–12. doi: https:/www.researchgate.net/publication/397709745_Ingen_okt_risiko_for_nevrodegenerativ_sykdom_hos_tidligere_kvinnelige_toppfotballspillere. Full text in Research Archive
• Dahlén, Sara; Bjørneboe, John Andreas; Sandmo, Stian Bahr; Bache-Mathiesen, Lena Kristin; Filipcik, Peter & Howe, Emilie Isager [Show all 12 contributors for this article] (2025). Brain health in female former top-level football players . Full text in Research Archive
• Dahlén, Sara; Bjørneboe, John Andreas; Sandmo, Stian Bahr; Bache-Mathiesen, Lena Kristin; Filipcik, Peter & Howe, Emilie Isager [Show all 12 contributors for this article] (2025). Brain health in Norwegian female former top-level football players: a protocol for a longitudinal cohort study. doi: 10.1136/bmjopen-2024-092456. Full text in Research Archive
• Dahlén, Sara (2024). Head impacts in top-level female football players. Full text in Research Archive
• Bjørneboe, John Andreas; Andersen, Thor Einar & Dahlén, Sara (2024). Brain health in female football players. Full text in Research Archive
• Dahlén, Sara (2024). HIT - Hodetraumer i Toppserien. Full text in Research Archive
• Dahlén, Sara (2023). Hodeskader. Full text in Research Archive
• Dahlén, Sara (2023). Brain health in female former football players. Full text in Research Archive
• Dahlén, Sara (2023). Brain health in female former football players. Full text in Research Archive
• Dahlén, Sara & Sandmo, Stian Bahr (2023). Diagnosis and management of concussion - practising the Sport Concussion Assessment Tool (SCAT5). Full text in Research Archive
• Holtzhausen, Louis; Dahlén, Sara; Sandmo, Stian Bahr & Andersen, Thor Einar (2023). Paneldiskusjon: Next steps in concussion awareness, diagnostics and management. Full text in Research Archive

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