Lena Kristin Bache-Mathiesen

Statistical methodology

• A new statistical approach to training load and injury risk: separating the acute from the chronic load. Bache-Mathiesen, LK, Andersen, TE, Dalen-Lorentsen, T, Tabben, M, Chamari, K, Clarsen, BM & Fagerland, MW (2023). Biology of Sport. doi: 10.5114/biolsport.2024.127388.

•  Assessing the cumulative effect of long-term training load on the risk of injury in team sports. Bache-Mathiesen, LK, Andersen, TE, Dalen-Lorentsen, T, Clarsen, BM & Fagerland, MW (2022). BMJ Open sport & exercise medicine. doi: 10.1136/bmjsem-2022-001342.

• Handling and reporting missing data in training load and injury risk research. Bache-Mathiesen, LK, Andersen, TE, Clarsen, B & Fagerland, MW (2021). Science and medicine in football. doi: 10.1080/24733938.2021.1998587. 

• Not straightforward: modelling non-linearity in training load and injury research. Bache-Mathiesen, LK, Andersen, TE, Dalen-Lorentsen, T, Clarsen, B & Fagerland, MW (2021). Science and medicine in football. doi: 10.1136/bmjsem-2021-001119.

Medicine (Causal inference)

• Causal inference did not detect any effect of jump load on knee complaints in elite men's volleyball. Bache-Mathiesen LK, Bahr R, Sattler T, Fagerland MW, Whiteley R, Skazalski C. Scand J Med Sci Sports (2024); 34:e14635. doi:10.1111/sms.14635
• Incidence and risk factors of intraoperative periprosthetic femoral fractures during primary total hip arthroplasty. Brüggemann, H, Dalen, I, Bache-Mathiesen, LK; Fenstad, AM, Hallan, G & Fosse, L (2022). Acta Orthopaedica. doi: 10.2340/17453674.2022.2431.

• Bache-Mathiesen, Lena Kristin; Bahr, Roald; Sattler, Tine; Fagerland, Morten Wang; Whiteley, Rod & Skazalski, Christopher M. (2024). Causal inference did not detect any effect of jump load on knee complaints in elite men's volleyball. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. 34(5). doi: 10.1111/sms.14635.
• Harøy, Joar; Bache-Mathiesen, Lena Kristin & Andersen, Thor Einar (2024). Lower HAGOS subscale scores associated with a longer duration of groin problems in football players in the subsequent season. BMJ Open sport & exercise medicine. ISSN 2055-7647. 10(2). doi: 10.1136/bmjsem-2023-001812.
• Chamari, Karim; Schumacher, Yorck Olaf; Chaabane, Mokhtar; Rekik, Raouf Nader; Chebbi, Souhail & Daoud, Ramadan [Show all 10 contributors for this article] (2023). Impact of COVID-19 lockdown on injury risk in Qatar's professional football. Journal of Science and Medicine in Sport. ISSN 1440-2440. doi: 10.1016/j.jsams.2023.09.008. Show summary

  Objectives: To compare injury incidence, burden and characteristics between the pre- and post-COVID-19 lockdown periods in Qatari professional football. Design: Prospective cohort study. Methods: Injury and exposure data for two post-COVID-19 lockdown periods [early post-lockdown period: short-term ~ 2 months (54 matches) and late post-lockdown period: long-term 8-months (183 matches)] were compared to the benchmark of the same periods from the three previous seasons (2017/18–2019/20). Results: We observed no difference in overall, training or match incidence between early post-lockdown period and the benchmark reference. However, this short-term period resulted in lower burden for overall- (RR 0.80, P < 0.0001), training- (RR 0.73, P < 0.0001) and match-injuries (RR 0.40, P < 0.0001) compared to the benchmark. During late post-lockdown period match injury incidence (RR 0.72, P = 0.0010) and match injury burden (RR 0.69, P < 0.001) were lower than the benchmark. In contrast, both overall- (RR 1.30, P < 0.001) and training-injury burden (RR 1.65, P < 0.001) were higher. A significant increase in adductor strains in both post-lockdown periods was observed. Conclusions: Immediately after the COVID-19 lockdown (short-term effect), there was no difference in injury incidence but a lower injury burden compared to benchmark. Moreover, the rapid return to competition for the successive season (long-term effect) was associated with a higher overall- and training-injury burden, but a lower match-injury burden compared to the benchmark.

• Harøy, Joar; Bache-Mathiesen, Lena Kristin & Andersen, Thor Einar (2023). Pre-season HAGOS scores associated with the number of weeks with groin problems. In Della Villa, F & Susta, D (Ed.), Football Medicine - The Pursuit of Excellence - Abstract book. Calzetti Maricci editori. ISSN 9788860286871.
• Bache-Mathiesen, Lena Kristin; Andersen, Thor Einar; Dalen-Lorentsen, Torstein; Tabben, Montassar; Chamari, Karim & Clarsen, Benjamin Matthew [Show all 7 contributors for this article] (2023). A new statistical approach to training load and injury risk: separating the acute from the chronic load. Biology of Sport. ISSN 0860-021X. 41(1), p. 119–134. doi: 10.5114/biolsport.2024.127388. Full text in Research Archive Show summary

  The relationship between recent (acute) training load relative to long-term (chronic) training load may be associated with sports injury risk. We explored the potential for modelling acute and chronic loads separately to address current statistical methodology limitations. We also determined whether there was any evidence of an interaction in the association between acute and chronic training loads and injury risk in football. A men’s Qatar Stars League football cohort (1 465 players, 1 977 injuries), where training load was defined as the number of minutes of activity, and a Norwegian elite U-19 football cohort (81 players, 60 injuries), where training load was defined as the session rating of perceived exertion (sRPE). Mixed logistic regression was run with training load on the current day (acute load) and cumulative past training load estimated by distributed lag non-linear models (chronic load) as independent variables. Injury was the outcome. An interaction between acute and chronic training load was modelled. In both football populations, we observed that the risk of injury on the current day for different values of acute training load was highest for players with low chronic load, followed by high and then medium chronic load. The slopes varied substantially between different levels of chronic training load, indicating an interaction. Modelling acute and chronic loads separately in regression models is a suitable statistical approach for analysing the association between relative training load and injury risk in injury prevention research. Sports scientists should also consider the potential for interactions between acute and chronic load.

• Nordstrøm, Anine; Bahr, Roald; Bache-Mathiesen, Lena Kristin; Clarsen, Benjamin Matthew & Talsnes, Ove (2022). Association of Training and Game Loads to Injury Risk in Junior Male Elite Ice Hockey Players: A Prospective Cohort Study. Orthopaedic Journal of Sports Medicine (OJSM). ISSN 2325-9671. 10(10). doi: 10.1177/23259671221129646. Full text in Research Archive Show summary

  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. Methods: In this prospective cohort study, we monitored all health problems among 159 male junior ice hockey players (mean age, 16 years; range, 15-19 years) at sports-specific high schools during the 2018-2019 school year. Players reported their health problems every week using the Oslo Sports Trauma Research Center Overuse Questionnaire on Health Problems (OSTRC-H2). The number of training sessions and games was reported for 33 weeks. We calculated the previous 2-week difference in training/game loads as well as the cumulative training/game loads of the previous 2, 3, 4, and 6 weeks and explored potential associations between training/game loads and injury risk using mixed-effects logistic regression. Results: The players reported 133 acute injuries, 75 overuse injuries, and 162 illnesses in total, and an average of 8.8 (SD ±3.9) training sessions and 0.9 (SD ± 1.1) games per week. We found no association between the difference of the two previous weeks or the previous 2- 3- and 4-week cumulative, training or game load and acute injuries, nor the difference of the two previous weeks, or the previous 4- and 6-week cumulative, training or game load and overuse injuries (OR, ∼1.0; P > .05 in all models). Conclusion: In the current study of junior elite ice hockey players, there was no evidence of an association between cumulative exposure to training/game loads and injury risk. This open-access article is published and distributed under the Creative Commons Attribution - NonCommercial - No Derivatives License (https://creativecommons.org/ licenses/by-nc-nd/4.0/), which permits the noncommercial use, distribution, and reproduction of the article in any medium, provided the original author and source are credited. You may not alter, transform, or build upon this article without the permission of the Author(s). For article reuse guidelines, please visit SAGE’s website at http://www.sagepub.com/journals-permissions

• Bache-Mathiesen, Lena Kristin; Andersen, Thor Einar; Dalen-Lorentsen, Torstein; Clarsen, Benjamin Matthew & Fagerland, Morten (2022). Assessing the cumulative effect of long-term training load on the risk of injury in team sports. BMJ Open sport & exercise medicine. ISSN 2055-7647. 8(2). doi: 10.1136/bmjsem-2022-001342. Full text in Research Archive Show summary

  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 of the effect of sRPE on injury risk and the effect of relative sRPE on injury risk were simulated. These scenarios assumed that the probability of injury was the result of training load exposures over the previous 4 weeks. We compared seven different methods of modelling training load in their ability to model the simulated relationship. We then used the most accurate method, the distributed lag non-linear model (DLNM), to analyse data from Norwegian youth elite handball players (no. of players=205, no. of health problems=471) to illustrate how assessing the cumulative effect of training load can be done in practice. Results: DLNM was the only method that accurately modelled the simulated relationships between training load and injury risk. In the handball example, DLNM could show the cumulative effect of training load and how much training load affected health problem risk depending on the distance in time since the training load exposure. Conclusion: DLNM can be used to assess the cumulative effect of training load on injury risk.

• Brüggemann, Heinrich; Dalen, Ingvild; Bache-Mathiesen, Lena Kristin; Fenstad, Anne Marie; Hallan, Geir & Fosse, Lars (2022). Incidence and risk factors of intraoperative periprosthetic femoral fractures during primary total hip arthroplasty: 218,423 cases reported to the Norwegian Arthroplasty Register between 1987 and 2020. Acta Orthopaedica. ISSN 1745-3674. 93, p. 405–412. doi: 10.2340/17453674.2022.2431. Full text in Research Archive Show summary

  Background and purpose: Intraoperative periprosthetic femoral fractures (IPFFs) can occur during primary total hip arthroplasty (THA). We describe the incidence of IPFFs during THA in Norway and estimate potential risk factors that could be associated with IPFF Patients and methods — Data from the Norwegian Arthoplasty Register (1987–2020) was used: 2,268 IPFFs from 218,423 primary THAs in 172,598 patients. The following factors were analyzed: sex, age, diagnosis, previous operation on the same hip, surgical approach, and stem fixation technique. Association of these factors with IPFF risk was assessed using multivariable Poisson regression. Results: IPFF occurred during 2,268 operations with an incidence of 1.0% among all primary THAs. The risk of IPFF was associated with female sex (relative risk 1.8; 99% CI 1.5–2.1), age 80–90 years and age over 90 years (compared with age 60–70 years: 1.3; CI 1.0–1.6 and 2.6; CI 1.6–4.3, respectively), non-osteoarthritis diagnoses (2.2; CI 1.9–2.6), previous surgery to the same hip (1.8; CI 1.5–2.2), lateral approach (compared with the posterior approach: 1.5; CI 1.1–2.0), and cementless stem fixation (2.7; CI 2.0–3.6). Interpretation: Surgeons should be aware of the factors associated with an increased risk of IPFF: female sex, age above 80 years, non-osteoarthritis diagnoses, and previous surgery to the same hip. Cemented stem fixation and posterior approach should be favored in high-risk patients, such as elderly women.

• Bache-Mathiesen, Lena Kristin; Andersen, Thor Einar; Clarsen, Benjamin & Fagerland, Morten Wang (2021). Handling and reporting missing data in training load and injury risk research. Science and medicine in football. ISSN 2473-3938. doi: 10.1080/24733938.2021.1998587. Show summary

  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 compare the accuracy of modelling a predetermined relationship between training load and injury risk following handling missing data with different methods. The simulations were based on a Norwegian Premier League men’s football dataset (n = 39). Internal training load was measured with the session Rating of Perceived Exertion (sRPE). External training load was the total distance covered measured by a global positioning systems (GPS) device. Results: Only 37 (34%) of 108 studies reported whether training load had any missing observations. Multiple Imputation using Predicted Mean Matching was the best method of handling missing data across multiple scenarios. Conclusion: Studies of training load and injury risk should report the extent of missing data, and how they are handled. Multiple Imputation with Predicted Mean Matching should be used when imputing sRPE and GPS variables.

• Bache-Mathiesen, Lena Kristin; Andersen, Thor Einar; Dalen-Lorentsen, Torstein; Clarsen, Benjamin Matthew & Fagerland, Morten (2021). Not straightforward: modelling non-linearity in training load and injury research. BMJ Open sport & exercise medicine. ISSN 2055-7647. 7(3), p. 1–9. doi: 10.1136/bmjsem-2021-001119. Full text in Research Archive Show summary

  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, mean age 26 years (SD 4)) and elite youth handball (n=205, 36% male, mean age 17 years (SD 1)). The relationship between session rating of perceived exertion (sRPE) and probability of injury was estimated with restricted cubic splines in mixed-effects logistic regression models. Simulations were carried out to compare the ability of seven methods to model non-linear relationships, using visualisations, root-mean-squared error and coverage of prediction intervals as performance metrics. Results: No relationships were identified in the football cohorts; however, a J-shaped relationship was found between sRPE and the probability of injury on the same day for elite youth handball players (p<0.001). In the simulations, the only methods capable of non-linear modelling relationships were the quadratic model, fractional polynomials and restricted cubic splines. Conclusion: The relationship between training load and injury risk should be assumed to be non-linear. Future research should apply appropriate methods to account for non-linearity, such as fractional polynomials or restricted cubic splines. We propose a guide for which method(s) to use in a range of different situations.

• Bjørndal, Christian T.; Bache-Mathiesen, Lena Kristin; Gjesdal, Siv; Moseid, Christine Holm; Myklebust, Grethe & Luteberget, Live (2021). An Examination of Training Load, Match Activities, and Health Problems in Norwegian Youth Elite Handball Players Over One Competitive Season. Frontiers in Sports and Active Living. ISSN 2624-9367. 3. doi: 10.3389/fspor.2021.635103. Full text in Research Archive Show summary

  Talent development is integral to the policy and organizational practice of competitive sport, but has also been associated with excessive amounts of training and competition, and athlete injuries and illnesses. The lack of available prospective data on the training and match activities of youth athletes and their health problems is therefore of concern. The aim of this study was two-fold: (a) to examine the amount and frequency of training load, match activities, injury and illness incidence, and prevalence among Norwegian youth elite handball players over the course of the 2018–2019 competitive season; and (b) to explore whether the injury rates are related to the sex or competition level of players, or their membership of the youth international team. We recruited 205 handball players (64% female, 36% male), aged 15–18 years (17.2 years ± 0.9) from five different sport school programs in southeast Norway. Data were collected daily from September 2018 to May 2019, during the competitive handball season. The variables included types of athlete activities, the number of activities, the rating of perceived exertion (RPE), and the duration of training and matches. Injury and illness data were collected weekly using the Oslo Sports Trauma Research Center (OSTRC) questionnaire. The mean number of matches per week per player was 0.9 ± 1.29; the number of weekly training events was 6.1 ± 4.4; and the mean weekly session RPE was 986 ± 1 412 arbitrary units. The players reported a total of 472 injuries, and the mean number of injuries per player was 2.3 ± 2.9. The results demonstrated a 53% weekly injury prevalence, of which 38% were categorized as substantial injuries. Male players and players who participated at the highest level of senior competition and/or the youth international team reported significantly lower weekly incidences of health problems, compared to other players. Our findings showed that players enrolled in sport school programs are exposed to high training and competition loads, and that both general and substantial health problems are common. The potential implications for talent development and future research are discussed.

• Butt, Noreen; Bache-Mathiesen, Lena Kristin; Ushakova, Anastasia; Nordrehaug, Jan Erik; Jensen, Senn-Erik & Munk, Peter Scott [Show all 15 contributors for this article] (2020). Pentraxin 3 in primary percutaneous coronary intervention for ST elevation myocardial infarction is associated with early irreversible myocardial damage: Kinetic profile, relationship to interleukin 6 and infarct size. European Heart Journal: Acute Cardiovascular Care. ISSN 2048-8726. 9(4), p. 302–312. doi: 10.1177/2048872620923641. Full text in Research Archive
• Kessler, Ute; Bjørke-Bertheussen, Janette; Søreide, Eldar; Hunderi, Per Anders; Bache-Mathiesen, Lena Kristin & Ødegaard, Ketil Joachim [Show all 8 contributors for this article] (2018). Remifentanil as an adjunct to anaesthesia for electroconvulsive therapy fails to confer long-term benefits. British Journal of Anaesthesia. ISSN 0007-0912. 121(6), p. 1282–1289. doi: 10.1016/j.bja.2018.07.011.
• Butt, Noreen; Bache-Mathiesen, Lena Kristin; Nordrehaug, Jan Erik; Tuseth, Vegard; Munk, Peter Scott & Bonarjee, Vernon V S [Show all 12 contributors for this article] (2017). Administration of the Mitochondrial Permeability Transition Pore Inhibitor, TRO40303, prior to Primary Percutaneous Coronary Intervention, Does Not Affect the Levels of Pro-Inflammatory Cytokines or Acute-Phase Proteins. Cardiology. ISSN 0008-6312. 138(2), p. 122–132. doi: 10.1159/000475460.

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• Bache-Mathiesen, Lena Kristin (2024). Monitoring Key Quality Indicators at the Faculty of Medicine.
• Visnes, Håvard; Bache-Mathiesen, Lena Kristin; Yamaguchi, Tetsuo; Hisdal, Erling & Bahr, Roald (2023). Hopperkne gir varig redusert knefunksjon hos unge volleyballspillere – en prospektiv kohortstudie med 11 års oppfølging.
• Tveiten, Caroline Emilie Van Woensel Ko; Jakobsen, Rune Bruhn; Bache-Mathiesen, Lena Kristin; Persson, Andreas; Myklebust, Grethe & Engebretsen, Lars [Show all 7 contributors for this article] (2023). Kommer utøvere på alle nivåer tilbake til vridningsidrett etter ACL rekonstruksjon?
• Tveiten, Caroline Emilie Van Woensel Ko; Jakobsen, Rune Bruhn; Bache-Mathiesen, Lena Kristin; Persson, Andreas; Myklebust, Grethe & Engebretsen, Lars [Show all 7 contributors for this article] (2023). Kommer utøvere på alle nivåer tilbake til vridningsidrett etter ACL rekonstruksjon?
• Visnes, Håvard; Bache-Mathiesen, Lena Kristin; Yamaguchi, Tetsuo; Hisdal, Erling & Bahr, Roald (2023). Hopperkne gir vedvarende redusert knefunksjon hos unge volleyballspillere – en prospektiv kohortstudie med 11 års oppfølging.
• Bache-Mathiesen, Lena Kristin (2023). Improving methodology in science and monitoring.
• Harøy, Joar; Bache-Mathiesen, Lena Kristin & Andersen, Thor Einar (2023). Pre-season HAGOS scores associated with the number of weeks with groin problems.
• Bache-Mathiesen, Lena Kristin (2023). Improving statistical methodology in training load and injury risk research (PhD Academy Award). British Journal of Sports Medicine. ISSN 0306-3674. doi: 10.1136/bjsports-2023-107200.
• Bache-Mathiesen, Lena Kristin (2023). Første doktorgrad i biostatistikk ved Norges idrettshøgskole taklet statistisk skandale i idrettsforskning. Tilfeldig gang. ISSN 0803-8953. 40(1), p. 5–8.
• Bache-Mathiesen, Lena Kristin (2023). De tøyer og de bøyer. Er det mulig å finne ut når de kan bli skadet? [Newspaper]. Khrono. Show summary

  Hun er egentlig biolog. Men Lena Kristin Bache-Mathiesen likte statistikk så godt at hun skiftet fagfelt.

• Bache-Mathiesen, Lena Kristin; Andersen, Thor Einar; Dalen-Lorentsen, Torstein; Tabben, Montassar; Chamari, Karim & Clarsen, Benjamin Matthew [Show all 7 contributors for this article] (2023). A new methodological approach to training load and injury risk.
• Bache-Mathiesen, Lena Kristin (2023). What's next in training load research?
• Bache-Mathiesen, Lena Kristin (2023). Analysing training load and injury risk.
• Nordstrøm, Anine; Bahr, Roald; Bache-Mathiesen, Lena Kristin; Clarsen, Benjamin Matthew & Talsnes, Ove (2022). Sammenhengen mellom trening- og kampbelastning og risiko for skade blant junior elite ishockeyspillere.
• Bache-Mathiesen, Lena Kristin; Andersen, Thor Einar & Fagerland, Morten (2022). Modelling non-linearity in training load and injury risk research: A simulation study.
• Bache-Mathiesen, Lena Kristin; Andersen, Thor Einar & Fagerland, Morten (2022). Estimating cumulative protracted time-lagged effects of training load on sports injury.
• Bache-Mathiesen, Lena Kristin; Andersen, Thor Einar & Fagerland, Morten (2022). Developments in injury prevention methodology research – missing data in training load.
• Bache-Mathiesen, Lena Kristin (2022). Improving methodology in training load and injury risk research.
• Bache-Mathiesen, Lena Kristin (2021). Missing data in training load and injury risk research.
• Bache-Mathiesen, Lena Kristin; Andersen, Thor Einar; Dalen-Lorentsen, Torstein; Clarsen, Benjamin Matthew & Fagerland, Morten (2021). A peek behind the study... [Journal]. BMJ Open Sport & Exercise Medicine.
• Bache-Mathiesen, Lena Kristin (2021). Missing data in training load and injury risk research.
• Bache-Mathiesen, Lena Kristin (2021). Visualisering av data.
• Bache-Mathiesen, Lena Kristin (2021). Treningsbelastning og skader hos unge håndballspillere.
• Bache-Mathiesen, Lena Kristin (2020). Forskning og metode.
• Bache-Mathiesen, Lena Kristin (2020). Visualisering av data.
• Bache-Mathiesen, Lena Kristin (2020). Visualisering av data.
• Bache-Mathiesen, Lena Kristin (2020). Exploring Non-Linearity in Load–Injury Research.
• Bache-Mathiesen, Lena Kristin (2020). Visualisering av data.
• Bache-Mathiesen, Lena Kristin (2020). Improving the Methodology of Training Load and Injury Research.
• Bache-Mathiesen, Lena Kristin (2019). Variabelutforming.
• Bache-Mathiesen, Lena Kristin (2017). Datakvalitet.
• Bache-Mathiesen, Lena Kristin (2017). Variabelutforming.
• Bache-Mathiesen, Lena Kristin; Fagerland, Morten & Andersen, Thor Einar (2023). Improving the Methodology of Training Load and Injury Risk Research: An Analysis of Analyses. Norges idrettshøgskole.

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