Tron Krosshaug

• Leppänen, Mari; Viiala, Janne; Kaikkonen, Piia; Tokola, Kari; Vasankari, Tommi & Nigg, Benno M. [Show all 10 contributors for this article] (2024). Hip and core exercise programme prevents running-related overuse injuries in adult novice recreational runners: A three-arm randomised controlled trial (Run RCT). British Journal of Sports Medicine. ISSN 0306-3674. doi: 10.1136/bjsports-2023-107926.
• Bill, Kevin; Mai, Patrick; Mausehund, Lasse; Solbakken, Sigurd; Krosshaug, Tron & Kersting, Uwe G. (2024). Individualized Technique Feedback for Instant Technique Improvements and Knee Abduction Moment Reductions – A New Approach for ‘Sidestepping’ ACL Injuries? International Journal of Sports Physical Therapy. ISSN 2159-2896. 19(5), p. 535–547. doi: 10.26603/001c.116274.
• Bagehorn, Timo; Bill, Kevin; Mai, Patrick; Krosshaug, Tron & Kersting, Uwe G. (2024). A biomechanical report of an acute lateral ankle sprain during a handball-specific cutting movement. Sports Biomechanics. ISSN 1476-3141. doi: 10.1080/14763141.2024.2319134.
• Mausehund, Lasse & Krosshaug, Tron (2024). Knee Biomechanics During Cutting Maneuvers and Secondary ACL Injury Risk: A Prospective Cohort Study of Knee Biomechanics in 756 Female Elite Handball and Soccer Players. American Journal of Sports Medicine. ISSN 0363-5465. 52(5). doi: 10.1177/03635465241234255.
• Hoenig, Tim; Rahlf, Lina; Wilke, Jan; Krauß, Inga; Dalos, Dimitris & Willwacher, Steffen [Show all 11 contributors for this article] (2023). Appraising the Methodological Quality of Sports Injury Video Analysis Studies: The QA-SIVAS Scale. Sports Medicine. ISSN 0112-1642. 54(1), p. 203–211. doi: 10.1007/s40279-023-01907-z. Full text in Research Archive
• Mai, Patrick; Bill, Kevin; Glöckler, Katharina; Claramunt-Molet, Mireia; Bartsch, Julia & Eggerud, Mathias M. [Show all 14 contributors for this article] (2022). Unanticipated fake-and-cut maneuvers do not increase knee abduction moments in sport-specific tasks: Implication for ACL injury prevention and risk screening. Frontiers in Sports and Active Living. ISSN 2624-9367. 4. doi: 10.3389/fspor.2022.983888. Full text in Research Archive Show summary

  Non-contact anterior cruciate ligament injuries typically occur during cutting maneuvers and are associated with high peak knee abduction moments (KAM) within early stance. To screen athletes for injury risk or quantify the efficacy of prevention programs, it may be necessary to design tasks that mimic game situations. Thus, this study compared KAMs and ranking consistency of female handball players in three sport-specific fake-and-cut tasks of increasing complexity. The biomechanics of female handball players (n = 51, mean ± SD: 66.9 ± 7.8 kg, 1.74 ± 0.06 m, 19.2 ± 3.4 years) were recorded with a 3D motion capture system and force plates during three standardized fake-and-cut tasks. Task 1 was designed as a simple pre-planned cut, task 2 included catching a ball before a pre-planned cut in front of a static defender, and task 3 was designed as an unanticipated cut with three dynamic defenders involved. Inverse dynamics were used to calculate peak KAM within the first 100 ms of stance. KAM was decomposed into the frontal plane knee joint moment arm and resultant ground reaction force. RANOVAs (α ≤ 0.05) were used to reveal differences in the KAM magnitudes, moment arm, and resultant ground reaction force for the three tasks. Spearman's rank correlations were calculated to test the ranking consistency of the athletes' KAMs. There was a significant task main effect on KAM (p = 0.02; η2p = 0.13). The KAM in the two complex tasks was significantly higher (task 2: 1.73 Nm/kg; task 3: 1.64 Nm/kg) than the KAM in the simplest task (task 1: 1.52 Nm/kg). The ranking of the peak KAM was consistent regardless of the task complexity. Comparing tasks 1 and 2, an increase in KAM resulted from an increased frontal plane moment arm. Comparing tasks 1 and 3, higher KAM in task 3 resulted from an interplay between both moment arm and the resultant ground reaction force. In contrast to previous studies, unanticipated cutting maneuvers did not produce the highest KAMs. These findings indicate that the players have developed an automated sport-specific cutting technique that is utilized in both pre-planned and unanticipated fake-and-cut tasks.

• Bill, Kevin; Mai, Patrick; Willwacher, Steffen; Krosshaug, Tron & Kersting, Uwe (2022). Athletes with high knee abduction moments show increased vertical center of mass excursions and knee valgus angles across sport-specific fake-and-cut tasks of different complexities. Frontiers in Sports and Active Living. ISSN 2624-9367. 4, p. 1–13. doi: 10.3389/fspor.2022.983889. Full text in Research Archive Show summary

  Young female handball players represent a high-risk population for anterior cruciate ligament (ACL) injuries. While the external knee abduction moment (KAM) is known to be a risk factor, it is unclear how cutting technique affects KAMs in sport-specific cutting maneuvers. Further, the effect of added game specificity (e.g., catching a ball or faking defenders) on KAMs and cutting technique remains unknown. Therefore, this study aimed: (i) to test if athletes grouped into different clusters of peak KAMs produced during three sport-specific fake-and-cut tasks of different complexities differ in cutting technique, and (ii) to test whether technique variables change with task complexity. Fifty-one female handball players (67.0 ± 7.7 kg, 1.70 ± 0.06 m, 19.2 ± 3.4 years) were recruited. Athletes performed at least five successful handball-specific sidestep cuts of three different complexities ranging from simple pre-planned fake-and-cut maneuvers to catching a ball and performing an unanticipated fake-and-cut maneuver with dynamic defenders. A k-means cluster algorithm with squared Euclidean distance metric was applied to the KAMs of all three tasks. The optimal cluster number of koptimal = 2 was calculated using the average silhouette width. Statistical differences in technique variables between the two clusters and the tasks were analyzed using repeated-measures ANOVAs (task complexity) with nested groupings (clusters). KAMs differed by 64.5%, on average, between clusters. When pooling all tasks, athletes with high KAMs showed 3.4° more knee valgus, 16.9% higher downward and 8.4% higher resultant velocity at initial ground contact, and 20.5% higher vertical ground reaction forces at peak KAM. Unlike most other variables, knee valgus angle was not affected by task complexity, likely due to it being part of inherent movement strategies and partly determined by anatomy. Since the high KAM cluster showed higher vertical center of mass excursions and knee valgus angles in all tasks, it is likely that this is part of an automated motor program developed over the players' careers. Based on these results, reducing knee valgus and downward velocity bears the potential to mitigate knee joint loading and therefore ACL injury risk.

• Jauhiainen, Susanne; Kauppi, Jukka-Pekka; Krosshaug, Tron; Bahr, Roald; Bartsch, Julia & Äyrämö, Sami (2022). Predicting ACL Injury Using Machine Learning on Data From an Extensive Screening Test Battery of 880 Female Elite Athletes. American Journal of Sports Medicine. ISSN 0363-5465. p. 2917–2924. doi: 10.1177/03635465221112095. Full text in Research Archive Show summary

  Background: Injury risk prediction is an emerging field in which more research is needed to recognize the best practices for accurate injury risk assessment. Important issues related to predictive machine learning need to be considered, for example, to avoid overinterpreting the observed prediction performance. Purpose: To carefully investigate the predictive potential of multiple predictive machine learning methods on a large set of risk factor data for anterior cruciate ligament (ACL) injury; the proposed approach takes into account the effect of chance and random variations in prediction performance. Study Design: Case-control study; Level of evidence, 3. Methods: The authors used 3-dimensional motion analysis and physical data collected from 791 female elite handball and soccer players. Four common classifiers were used to predict ACL injuries (n = 60). Area under the receiver operating characteristic curve (AUC-ROC) averaged across 100 cross-validation runs (mean AUC-ROC) was used as a performance metric. Results were confirmed with repeated permutation tests (paired Wilcoxon signed-rank-test; P < .05). Additionally, the effect of the most common class imbalance handling techniques was evaluated. Results: For the best classifier (linear support vector machine), the mean AUC-ROC was 0.63. Regardless of the classifier, the results were significantly better than chance, confirming the predictive ability of the data and methods used. AUC-ROC values varied substantially across repetitions and methods (0.51-0.69). Class imbalance handling did not improve the results. Conclusion: The authors’ approach and data showed statistically significant predictive ability, indicating that there exists information in this prospective data set that may be valuable for understanding injury causation. However, the predictive ability remained low from the perspective of clinical assessment, suggesting that included variables cannot be used for ACL prediction in practice.

• Lysdal, Filip Gertz; Wang, Yuehang; Delahunt, Eamonn; Gehring, Dominic; Kosik, Kyle B. & Krosshaug, Tron [Show all 12 contributors for this article] (2022). What have we learnt from quantitative case reports of acute lateral ankle sprains injuries and episodes of ‘giving-way’ of the ankle joint, and what shall we further investigate? Sports Biomechanics. ISSN 1476-3141. 21(4), p. 359–379. doi: 10.1080/14763141.2022.2035801. Full text in Research Archive Show summary

  Lateral ankle sprains are a commonly incurred injury in sports. They have a high recurrence rate and can lead to the development of persistent injury associated symptoms. We performed a quantitative synthesis of published case reports documenting the kinematics of acute lateral ankle sprains and episodes of ‘giving-way’ of the ankle joint to provide a comprehensive description of the mechanisms. A systematic literature search was conducted to screen records within MEDLINE® and EMBASE®. Additional strategies included manual search of specific journals, as well as contacting researchers in relevant communities to retrieve unpublished data. Twenty-four cases were included in the quantitative synthesis, 11 from individual case reports and 13 from four separate case series. Two authors independently reviewed all the articles and extracted ankle joint kinematic data. Excessive ankle inversion was the most pronounced kinematic pattern observed across all included cases, with a mean peak inversion angle of 67.5° (range 2.0 to 142) and a mean peak inversion velocity of 974°/s (range 468 to 1752). This was followed by internal rotation and plantar flexion, respectively. A homogeneous linear function revealed a mean inversion velocity across all cases of 337°/s (range 117 to 1400; R2 = 0.78; p < 0.0001).

• Mausehund, Lasse & Krosshaug, Tron (2021). Understanding Bench Press Biomechanics — Training Expertise and Sex Affect Lifting Technique and Net Joint Moments. Journal of Strength and Conditioning Research. ISSN 1064-8011. doi: 10.1519/JSC.0000000000004191. Show summary

  The purpose of this study was to compare normalized net joint moments (NJMs), moment arms, and muscle activity in the bench press exercise between powerlifters and recreationally strength-trained lifters and between women and men. Thirty-four healthy adults, including 12 powerlifters (6 women and 6 men) and 22 recreational lifters (9 women and 13 men), performed a 6–8 repetition maximum set of the bench press, while elbow and shoulder NJMs and moment arms and electromyographic (EMG) activity of 6 upper extremity muscles were recorded. The results showed that training expertise and sex affected bench press technique substantially. Powerlifters applied a different bar path which impacted joint kinematics to a greater extent and joint kinetics to a lesser extent. Specifically, powerlifters had lower normalized peak elbow NJMs and shorter joint ROMs than recreational lifters (p ≤ 0.05), yet no differences in normalized shoulder NJMs and muscle activity were observed. Women showed lower normalized mean shoulder NJMs, higher normalized peak elbow NJMs, and higher mean elbow to shoulder NJM ratios than men (p ≤ 0.05). The muscle activity of the long head of the triceps brachii and the elbow to shoulder EMG ratio were higher, yet muscle activity of the sternocostal and abdominal head of the pectoralis major was lower for female than for male subjects (p ≤ 0.05). In conclusion, powerlifters and men are more shoulder dominant when performing the bench press than recreational lifters and women, respectively. These findings will have implications for resistance training program design, expected training adaptations and bench press performance.

• Jauhiainen, Susanne; Krosshaug, Tron; Petushek, Erich; Kauppi, Jukka-Pekka & Äyrämö, Sami (2021). Information Extraction from Binary Skill Assessment Data with Machine Learning. International Journal of Learning Analytics and Artificial Intelligence for Education (IJAI). ISSN 2706-7564. 3(1), p. 20–35. doi: 10.3991/ijai.v3i1.24295. Full text in Research Archive Show summary

  Strength training exercises are essential for rehabilitation, improving our health as well as in sports. For optimal and safe training, educators and trainers in the industry should comprehend exercise form or technique. Currently, there is a lack of tools measuring in-depth skills of strength training experts. In this study, we investigate how data mining methods can be used to identify novel and useful skill patterns from a binary multiple choice questionnaire test designed to measure the knowledge level of strength training experts. A skill test assessing exercise technique expertise and comprehension was answered by 507 fitness professionals with varying backgrounds. A triangulated approach of clustering and non-negative matrix factorization (NMF) was used to discover skill patterns among participants and patterns in test questions. Four distinct participant subgroups were identified in data with clustering and further question patterns with NMF. The results can be used to, for example, identify missing skills and knowledge in participants and subgroups of participants and form general and personalized or background specific guidelines for future education. In addition, the test can be optimized based on, for example, if some questions can be answered correct even without the required skill or if they seem to be measuring overlapping skills. Finally, this approach can be utilized with other multiple choice test data in future educational research.

• Álvarez-Zafra, Marta; Yanci, Javier; García-Tabar, Ibai; Bikandi, Eder; Etxaleku, Saioa & Izquierdo, Mikel [Show all 9 contributors for this article] (2021). Functional and Anthropometrical Screening Test among High Performance Female Football Players: A Descriptive Study with Injury Incidence Analysis, the Basque Female Football Cohort (BFFC) Study. International Journal of Environmental Research and Public Health (IJERPH). ISSN 1661-7827. 18(20). doi: 10.3390/ijerph182010658. Full text in Research Archive Show summary

  The main objectives of the present study were to describe the injury incidence and to analyze the anthropometric and physical characteristics of players from three high-level women’s football teams. The present study involved 54 female football players (21.9 ± 4.9 years old) from three different teams competing in the Spanish Reto Iberdrola-Segunda División PRO league. A battery of tests was carried out to determine the anthropometric and physical performance characteristics of the players along with an injury incidence record during a full competitive season. The obtained results showed that there was a high incidence of injury, as 38% of the players suffered some type of injury during the season (range 1–5; 1.75 ± 1.02 injuries per player). Injuries occurred in both matches and during training at a similar percentage (48.6 vs. 51.4%), and the majority of the registered episodes were graded as moderate or severe injury types (60%). Players suffering from an injury accumulated a total of 1587 chronological days off work due to injury during the season, with a recurrence rate of 55%. Considering the high incidence of injury, and the injury burden and the reinjure rate observed in this research, it seems necessary to apply the most efficient prevention and recovery measures possible in these female football teams. These descriptive data could serve athletic trainers and medical staff of female football teams to better understand their own screening procedure-derived data.

• Richter, Chris; Petushek, Erich; Grindem, Hege; Franklyn-Miller, Andrew; Bahr, Roald & Krosshaug, Tron (2021). Cross-validation of a machine learning algorithm that determines anterior cruciate ligament rehabilitation status and evaluation of its ability to predict future injury. Sports Biomechanics. ISSN 1476-3141. doi: 10.1080/14763141.2021.1947358. Full text in Research Archive Show summary

  Classification algorithms determine the similarity of an observation to defined classes, e.g., injured or healthy athletes, and can highlight treatment targets or assess progress of a treatment. The primary aim was to cross-validate a previously developed classification algorithm using a different sample, while a secondary aim was to examine its ability to predict future ACL injuries. The examined outcome measure was ‘healthy-limb’ class membership probability, which was compared between a cohort of athletes without previous or future (No Injury) previous (PACL) and future ACL injury (FACL). The No Injury group had significantly higher probabilities than the PACL (p < 0.001; medium effect) and FACL group (p ≤ 0.045; small effect). The ability to predict group membership was poor for the PACL (area under curve [AUC]; 0.61<AUC<0.62) and FACL group (0.57<AUC<0.59). The ACL injury incidence proportion was highest in athletes with probabilities below 0.20 (9.4%; +2.7% to baseline), while athletes with probabilities above 0.80 had an incidence proportion of 4.1% (−2.6%). While findings that a low probability might represent an increase in injury risk on a group level, it is not sensitive enough for injury screening to predict a future injury on the individual level.

• Leppänen, Mari; Parkkari, Jari; Vasankari, Tommi; Äyrämö, Sami; Kulmala, Juha-Pekka & Krosshaug, Tron [Show all 8 contributors for this article] (2021). Change of Direction Biomechanics in a 180-Degree Pivot Turn and the Risk for Noncontact Knee Injuries in Youth Basketball and Floorball Players. American Journal of Sports Medicine. ISSN 0363-5465. 49(10), p. 2651–2658. doi: 10.1177/03635465211026944. Full text in Research Archive Show summary

  Background: Studies investigating biomechanical risk factors for knee injuries in sport-specific tasks are needed. Purpose: To investigate the association between change of direction (COD) biomechanics in a 180-degree pivot turn and knee injury risk among youth team sport players. Study Design: Cohort study; Level of evidence, 2. Methods: A total of 258 female and male basketball and floorball players (age range, 12-21 years) participated in the baseline COD test and follow-up. Complete data were obtained from 489 player-legs. Injuries, practice, and game exposure were registered for 12 months. The COD test consisted of a quick ball pass before and after a high-speed 180-degree pivot turn on the force plates. The following variables were analyzed: peak vertical ground-reaction force (N/kg); peak trunk lateral flexion angle (degree); peak knee flexion angle (degree); peak knee valgus angle (degree); peak knee flexion moment (N·m/kg); peak knee abduction moment (N·m/kg); and peak knee internal and external rotation moments (N·m/kg). Legs were analyzed separately and the mean of 3 trials was used in the analysis. Main outcome measure was a new acute noncontact knee injury. Results: A total of 18 new noncontact knee injuries were registered (0.3 injuries/1000 hours of exposure). Female players sustained 14 knee injuries and male players 4. A higher rate of knee injuries was observed in female players compared with male players (incidence rate ratio, 6.2; 95% CI, 2.1-21.7). Of all knee injuries, 8 were anterior cruciate ligament (ACL) injuries, all in female players. Female players displayed significantly larger peak knee valgus angles compared with male players (mean for female and male players, respectively: 13.9°± 9.4° and 2.0°± 8.5°). No significant associations between biomechanical variables and knee injury risk were found. Conclusion: Female players were at increased risk of knee and ACL injury compared with male players. Female players performed the 180-degree pivot turn with significantly larger knee valgus compared with male players. However, none of the investigated variables was associated with knee injury risk in youth basketball and floorball players.

• Petushek, Erich; Nilstad, Agnethe; Bahr, Roald & Krosshaug, Tron (2021). Drop Jump? Single-Leg Squat? Not if You Aim to Predict Anterior Cruciate Ligament Injury From Real-Time Clinical Assessment: A Prospective Cohort Study Involving 880 Elite Female Athletes. Journal of Orthopaedic and Sports Physical Therapy. ISSN 0190-6011. 51(7), p. 372–378. doi: 10.2519/jospt.2021.10170. Show summary

  Objective: To determine whether visually assessed performances of the single-leg squat (SLS) and vertical drop jump (VDJ) were associated with future noncontact anterior cruciate ligament (ACL) injury. Design: Prognostic accuracy cohort study. Methods: Elite female handball and football (soccer) athletes (n = 880) were tested from 2007 to 2014 and tracked through 2015. Trained physical therapists visually rated each leg during a SLS and overall control during a VDJ. Receiver operating characteristic curve, Pearson chi-square, and logistic regression analyses were used to determine the prognostic accuracy of the 2 screening tests. Results: Sixty-five noncontact ACL injuries occurred during the follow-up period. Fourteen percent of athletes who sustained an ACL injury had poor SLS performance, compared to 17% of the noninjured athletes (P = .52 and .67 for hip and knee ratings, respectively). Side-to-side asymmetry in the SLS was not different between injured and noninjured athletes (P = .10 and .99 for hip and knee asymmetry, respectively). Twenty-one percent of athletes who sustained an ACL injury had a poor VDJ rating, compared to 27% of the noninjured athletes (P = .09). Furthermore, area under the curve values ranged from 0.43 to 0.54 for the SLS and VDJ, demonstrating no to poor prognostic accuracy. Conclusion: Neither SLS nor VDJ test performance distinguished between athletes who sustained a subsequent noncontact ACL injury and those who did not.

• Nilstad, Agnethe; Petushek, Erich; Mok, Kam-Ming; Bahr, Roald & Krosshaug, Tron (2021). Kiss goodbye to the ‘kissing knees’: no association between frontal plane inward knee motion and risk of future non-contact ACL injury in elite female athletes. Sports Biomechanics. ISSN 1476-3141. doi: 10.1080/14763141.2021.1903541. Full text in Research Archive Show summary

  he aim of this study was to investigate if frontal plane knee and hip control in single-leg squats or vertical drop jumps with an overhead target were associated with future non-contact anterior cruciate ligament (ACL) injury in elite female athletes. Of the 429 handball and 451 football athletes (age 21.5 ± 4.0 years, height 169.6 ± 6.4 cm, body weight 67.1 ± 8.0 kg), 722 non-injured and 56 non-contact ACL injured participants were eligible for analysis. We calculated lateral pelvic tilt, frontal plane knee projection angle, medial knee position, and side-to-side asymmetry in these from 2D videos recorded at baseline, and recorded any new ACL injuries prospectively. None of the aforementioned variables in either screening task were different or could discriminate between injured and non-injured athletes (all p values >.05 and Cohen’s d values < .27). Two-dimensional video assessment of frontal plane knee and hip control during both a single-leg squat and vertical drop jump was unable to identify individuals at increased risk of non-contact ACL injury, thus should not be used for screening.

• Mausehund, Lasse; Werkhausen, Amelie; Bartsch, Julia & Krosshaug, Tron (2021). Understanding Bench Press Biomechanics-The Necessity of Measuring Lateral Barbell Forces. Journal of Strength and Conditioning Research. ISSN 1064-8011. 36(10), p. 2685–2695. doi: 10.1519/JSC.0000000000003948. Show summary

  The purpose of this study was to advance the expertise of the bench press exercise by complementing electromyographic (EMG) with net joint moment (NJM) and strength normalized NJM (nNJM) measurements, thus establishing the magnitude of the elbow and shoulder muscular loads and efforts. Normalized NJMs were determined as the ratio of the bench press NJMs to the maximum NJMs produced during maximum voluntary isokinetic contractions. Furthermore, we wanted to assess how changes in grip width and elbow positioning affected elbow and shoulder NJMs and nNJMs, and muscle activity of the primary movers. Thirty-five strength-trained adults performed a 6–8 repetition maximum set of each bench press variation, while elbow and shoulder NJMs and EMG activity of 7 upper extremity muscles were recorded. The results show that all bench press variations achieved high elbow and shoulder muscular efforts. A decrease in grip width induced larger elbow NJMs, and larger EMG activity of the lateral head of the triceps brachii, anterior deltoid, and clavicular head of the pectoralis major (p ≤ 0.05). An increase in grip width elicited larger shoulder NJMs and nNJMs, and larger EMG activity of the abdominal head of the pectoralis major (p ≤ 0.05). In conclusion, all bench press variations may stimulate strength gains and hypertrophy of the elbow extensors and shoulder flexors and horizontal adductors. However, greater adaptations of the elbow extensors and shoulder flexors may be expected when selecting narrower grip widths, whereas wider grip widths may induce greater adaptations of the shoulder horizontal adductors.

• Patton, Declan A.; McIntosh, Andrew S.; Hagel, Brent & Krosshaug, Tron (2020). A Review of Head Injury and Impact Biomechanics in Recreational Skiing and Snowboarding. Muscles, Ligaments and Tendons Journal (MLTJ). 10(2), p. 211–232. doi: 10.32098/mltj.02.2020.07. Full text in Research Archive Show summary

  Background: Skiing and snowboarding are popular competitive and recreational sports with associated head injury risks from impact hazards. Understanding head injury hazards and risks in snow sports can inform injury prevention measures, such as helmets, education and environment design of runs and terrain park features, to manage injury risk. Aim: To identify and discuss (a) the proportion and incidence of head injuries and effectiveness of helmets, (b) circumstances, situational events and characteristics of head injuries and (c) head impact biomechanics in recreational skiing and snowboarding. Methods: A narrative literature review was performed. Results: Head injuries comprise up to 38% and 29% of all injuries in skiing and snowboarding, respectively. Skull fractures were found to comprise nearly half of all moderate to severe head injuries in alpine sports across all studies. The most common intracranial injury in skiing and snowboarding was cerebral contusion and subdural haematoma, respectively. Fatal head injuries in skiing are rare with an incidence of approximately one death per one million skier-visits and less than 1% of all skiing head injuries resulted in death. The majority of head injuries were sustained by novice and intermediate level skiers and snowboarders during falls on mild or moderate gradient slopes. Head injury cases occurred in terrain parks were more common in snowboarders than skiers. Fall-related head injuries to skiers are typically in the forward direction with an impact to the front of the head, whereas snowboarders fall rearward and impact the occipital region. Helmet use has increased in recent years, but recent studies have observed an unexpected reduction of the protective effect of helmets in skiing and snowboarding. Alpine sports helmet standards require linear drops onto rigid anvils, but the correlation with snow surfaces is unknown and no helmet standard requires an oblique impact test. Significant protective effects of helmets have been found for collisions and falls onto hard snow. Conclusions: Alpine sport helmet performance standards should more closely reflect the boundary conditions of impacts to skiers and snowboarders associated with head injury. Administrative and engineering controls may also reduce the risk of head injury in skiing and snowboarding.

• Räisänen, Anu; Kulmala, Tanja; Parkkari, Jari; Vasankari, Tommi; Kannus, Pekka & Krosshaug, Tron [Show all 10 contributors for this article] (2020). There Is No Relationship Between Lower Extremity Alignment During Unilateral and Bilateral Drop Jumps and the Risk of Knee or Ankle Injury: A Prospective Study. Journal of Orthopaedic and Sports Physical Therapy. ISSN 0190-6011. 50(5), p. 267–274. doi: 10.2519/jospt.2020.9247. Show summary

  Objective: To investigate the association between lower extremity alignment during unilateral and bilateral drop jump tests and the risk of acute noncontact knee or ankle injuries in young team sport athletes. Design: Prospective cohort study. Methods: A 2-dimensional video analysis was used to measure the frontal plane knee projection angle in the single-leg vertical drop jump (VDJ) and the bilateral VDJ in young team sport athletes. Out of the 364 athletes (187 male, 177 female), 189 played basketball and 175 played floorball. Results: Six male athletes sustained knee injuries and 23 sustained ankle injuries. Frontal plane knee projection angle in the single-leg VDJ or the bilateral VDJ was not associated with ankle injuries among male athletes. No statistical analysis was performed for the knee injuries. Among female athletes, 28 sustained knee and 41 sustained ankle injuries. Frontal plane knee projection angle during the single-leg VDJ or the bilateral VDJ was not a risk factor for knee or ankle injuries. Conclusion: Lower extremity alignment during unilateral and bilateral drop jump tests was not associated with future noncontact knee or ankle injuries among young team sport athletes. The findings should be interpreted cautiously due to the small number of injuries.

• Leppänen, Mari; Rossi, Marco T.; Parkkari, Jari; Heinonen, Ari; Äyrämö, Sami & Krosshaug, Tron [Show all 9 contributors for this article] (2020). Altered hip control during a standing knee‐lift test is associated with increased risk of knee injuries. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. 30(5), p. 922–931. doi: 10.1111/sms.13626. Full text in Research Archive Show summary

  A few prospective studies have investigated hip and pelvic control as a risk factor for lower extremity (LE) injuries. The purpose of this study was to investigate whether deficits in hip and lumbopelvic control during standing knee‐lift test are associated with increased risk of acute knee and LE injuries in youth team sports. At baseline, 258 basketball and floorball players (aged 12‐21 years) participated in a standing knee‐lift test using 3‐dimensional motion analysis. Two trials per leg were recorded from each participant. Peak sagittal plane pelvic tilt and frontal plane pelvic drop/hike were measured. Both continuous and categorical variables were analyzed. New non‐contact LE injuries, and match and training exposure, were recorded for 12 months. Seventy acute LE injuries were registered. Of these, 17 were knee injuries (eight ACL ruptures) and 35 ankle injuries. Risk factor analyses showed that increased contralateral pelvic hike was significantly associated with knee injury risk when using categorical variable (HR for high vs low group 4.07; 95% CI 1.32‐12.6). Furthermore, significant association was found between high lateral pelvic hike angles and ACL injury risk in female players (HR for high vs low group 9.10; 95% CI 1.10‐75.2). Poor combined sensitivity and specificity of the test was observed. In conclusion, increased contralateral pelvic hike is associated with non‐contact knee injury risk among young team sport players and non‐contact ACL injuries among female players. More research to determine the role of pelvic control as a risk factor for knee injuries is needed.

• Mørtvedt, Anne Inger; Krosshaug, Tron; Bahr, Roald & Petushek, Erich (2019). I spy with my little eye … a knee about to go ‘pop’? Can coaches and sports medicine professionals predict who is at greater risk of ACL rupture? British Journal of Sports Medicine. ISSN 0306-3674. 54(3). doi: 10.1136/bjsports-2019-100602. Full text in Research Archive Show summary

  Background: The vertical drop jump (VDJ) test is widely used for clinical assessment of ACL injury risk, but it is not clear whether such assessments are valid. Aim: To examine if sports medicine professionals and coaches are able to identify players at risk of sustaining an ACL injury by visually assessing player performance during a VDJ test. Methods: 102 video clips of elite female handball and football players performing a baseline VDJ test were randomly extracted from a 738-person prospective cohort study that tracked ACL injuries. Of the sample, 20 of 102 went on to suffer an ACL injury. These 102 videos were uploaded to an online survey. Sports medicine professionals and coaches were invited to assess athlete performance and rate each clip with a number between 1 and 10 (1 representing low risk of sustaining an ACL injury and 10 representing high risk). Receiver operating characteristic analyses were used to assess classification accuracy and between-group differences were analysed using one-way analysis of variance. Results: 237 assessors completed the survey. Area under the curve values ranged from 0.36 to 0.60, with a mean score of 0.47, which is similar to random guessing. There were no significant differences in classification accuracy between groups (physicians, coaches, certified athletic trainers, researchers or physical therapists). Conclusion: Assessors have poor predictive ability (no better than chance), indicating that visual assessment of a VDJ test is a poor test for assessing ACL injury risk in elite female handball and football players.

• Tierney, Gregory J.; Gildea, Kevin; Krosshaug, Tron & Simms, Ciaran K. (2019). Analysis of ball carrier head motion during a rugby union tackle without direct head contact: A case study. International journal of sports science & coaching. ISSN 1747-9541. 14(2), p. 190–196. doi: 10.1177/1747954119833477. Full text in Research Archive Show summary

  Rugby union players can be involved in many tackles per game. However, little is known of the regular head loadingenvironment associated with tackling in rugby union. In particular, the magnitude and influencing factors for head kine-matics during the tackle are poorly understood. Accordingly, the goal of this study was to measure head motion of avisually unaware ball carrier during a real game tackle to the upper trunk with no direct head contact, and compare thekinematics with previously reported concussive events. Model-Based Image-Matching was utilised to measure ball carrierhead linear and angular velocities. Ball carrier componential maximum change in head angular velocities of 38.1, 20.6 and13.5 rad/s were measured for the head local X (coronal plane), Y (sagittal plane) and Z (transverse plane) axes respect-ively. The combination of a high legal tackle height configuration and visually unaware ball carrier can lead to kinematicssimilar to average values previously reported for concussive direct head impacts.

• Mausehund, Lasse; Skard, Audun Eithun & Krosshaug, Tron (2019). Muscle Activation in Unilateral Barbell Exercises: Implications for Strength Training and Rehabilitation. Journal of Strength and Conditioning Research. ISSN 1064-8011. 33, p. S85–S94. doi: 10.1519/JSC.0000000000002617. Full text in Research Archive Show summary

  The purpose of the present investigation was to assess lower-body muscle activity and hamstrings-to-quadriceps (HQ) activation ratios during performance of the split squat (SS), single-leg squat (SLS), and rear foot elevated split squat (RFESS), while using the same relative load and performing the exercises to muscular failure. Eleven healthy, moderately strength-trained subjects performed a 6–8 repetition maximum set of each exercise while electromyographic (EMG) activity of the vastus lateralis, biceps femoris, gluteus maximus, and gluteus medius was recorded. The results show that there were no significant differences in EMG peak activity of the gluteus maximus and vastus lateralis between any of the exercises. Gluteus medius activation was significantly (p # 0.05) higher during the SLS (81.9% maximum voluntary isometric contraction [MVIC]), compared with the RFESS (54.9% MVIC) and SS (46.2% MVIC). The RFESS elicited higher (p # 0.05) biceps femoris activity (76.1% MVIC) than the SS (62.3% MVIC), as well as higher (p # 0.05) HQ activation ratios (0.83) than the SS (0.69) and SLS (0.63). During the SLS and the SS, HQ activation ratios increased significantly in the course of the repetition maximum set. In conclusion, although absolute loading differs between exercises, similar training stimuli of the gluteus maximus and quadriceps femoris can be expected for all exercises. The SLS is likely to induce the greatest improvements in gluteus medius strength, whereas the RFESS should be preferred if high hamstring coactivation is desired. To improve validity in EMG studies, strength training exercises should be performed close to failure while using the same relative loading.

• Räisänen, Anu; Pasanen, Kati; Krosshaug, Tron; Vasankari, Tommi; Kannus, Pekka & Heinonen, Ari [Show all 10 contributors for this article] (2018). Association between frontal plane knee control and lower extremity injuries: a prospective study on young team sport athletes. BMJ Open sport & exercise medicine. ISSN 2055-7647. 4. doi: 10.1136/%20bmjsem-2017-000311. Full text in Research Archive Show summary

  Background/aim: Poor frontal plane knee control can manifest as increased dynamic knee valgus during athletic tasks. The purpose of this study was to investigate the association between frontal plane knee control and the risk of acute lower extremity injuries. In addition, we wanted to study if the single-leg squat (SLS) test can be used as a screening tool to identify athletes with an increased injury risk. Methods: A total of 306 basketball and floorball players participated in the baseline SLS test and a 12-month injury registration follow-up. Acute lower extremity time-loss injuries were registered. Frontal plane knee projection angles (FPKPA) during the SLS were calculated using a two-dimensional video analysis. Results: Athletes displaying a high FPKPA were 2.7 times more likely to sustain a lower extremity injury (adjusted OR 2.67, 95% CI 1.23 to 5.83) and 2.4 times more likely to sustain an ankle injury (OR 2.37, 95% CI 1.13 to 4.98). There was no statistically significant association between FPKPA and knee injury (OR 1.49, 95% CI 0.56 to 3.98). The receiver operating characteristic curve analyses indicated poor combined sensitivity and specificity when FPKPA was used as a screening test for lower extremity injuries (area under the curve of 0.59) and ankle injuries (area under the curve of 0.58). Conclusions: Athletes displaying a large FPKPA in the SLS test had an elevated risk of acute lower extremity and ankle injuries. However, the SLS test is not sensitive and specific enough to be used as a screening tool for future injury risk.

• Risberg, May Arna; Steffen, Kathrin; Nilstad, Agnethe; Myklebust, Grethe; Kristianslund, Eirik & Moltubakk, Marie M. [Show all 7 contributors for this article] (2018). Normative Quadriceps and Hamstring Muscle Strength Values for Female, Healthy, Elite Handball and Football Players. Journal of Strength and Conditioning Research. ISSN 1064-8011. 32(8), p. 2314–2323. doi: 10.1519/JSC.0000000000002579. Full text in Research Archive Show summary

  This study presents normative values for isokinetic knee extension and flexion muscle strength tests in 350 elite, female, handball (n = 150) and football (n = 200) players. Isokinetic concentric muscle strength tests at 60°·sec−1 were recorded bilaterally using a dynamometer. Peak torque (in Newton meter [N·m]), body mass normalized peak torque (N·m·kg−1), and hamstring to quadriceps ratio (H:Q ratio) for dominant and nondominant legs were recorded. The female elite players were 20.9 ± 4.0 years, started playing at the elite level at the age of 18.2 ± 2.7 years, with a mean of 9.7 ± 2.2 hours of weekly in-season training. Handball players demonstrated greater quadriceps muscle strength compared with football players (11.0%) (p < 0.001), also when normalized to body mass (4.1%) (p = 0.012), but not for weight-adjusted hamstring muscle strength. The H:Q ratio was higher on the dominant compared with the nondominant leg for handball players only (p = 0.012).The H:Q ratio was significantly lower for handball players (0.58) compared with football players (0.60) (p < 0.02). These normative values for isokinetic knee extension and flexion torques of healthy, elite, female handball and football players can be used to set rehabilitation goals for muscle strength after injury and enable comparison with uninjured legs. Significantly greater quadriceps muscle strength was found for handball players compared with football players, also when normalized to body mass.

• Dæhlin, Torstein Eriksen; Krosshaug, Tron & Chiu, Loren Z.F. (2018). Distribution of lower extremity work during clean variations performed with different effort. Journal of Sports Sciences. ISSN 0264-0414. 36(19), p. 2242–2249. doi: 10.1080/02640414.2018.1449087. Full text in Research Archive Show summary

  The purpose of this research was to investigate how lower extremity work was distributed during the pull of cleans performed lifting the barbell to the minimum height required to receive it in a full squat (minimal height clean); or with maximum effort to elevate the barbell as high as possible and receiving it in either a full (maximal effort clean) or partial (power clean) squat. Eight weightlifters screened for proficient technique performed these clean variations at 80% of one repetition maximum. Work performed on the barbell and by the lower extremity net joint moments (NJM) was computed from marker trajectories and ground reaction forces. Total barbell work, lower extremity NJM work, knee extensor work, and knee joint excursion during the second pull was lower in the minimal height clean than the maximal effort and power cleans (P < 0.05). This research demonstrates that more knee extensor work is performed in the second pull of maximal effort and power cleans compared to the minimal height clean. The larger knee extensor work performed is due to larger knee joint excursion during the second pull of the maximal effort and power cleans, but not larger knee extensor NJM.

• Sasaki, Shogo; Koga, Hideyuki; Krosshaug, Tron; Kaneko, Satoshi & Fukubayashi, Toru (2018). Kinematic analysis of pressing situations in female collegiate football games: New insight into anterior cruciate ligament injury causation. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. 28(3), p. 1263–1271. doi: 10.1111/sms.13018. Full text in Research Archive Show summary

  The most common events during which anterior cruciate ligament (ACL) injuries occur in football are pressing situations. This study aimed to describe the knee and hip joint kinematics during pressing situations in football games to identify kinematic patterns in actions with a high risk for ACL injuries. We filmed 5 female collegiate football matches and identified 66 pressing situations. Five situations with a large distance between the trunk and foot placements in the sagittal plane were analyzed using a model-based image-matching technique. The mean knee flexion angle at initial contact (IC) was 13° (range, 8°-28°) and increased by 11° (95% confidence interval [CI], 3°-14°) at 40 ms after IC. As for knee adduction and rotation angles, the knee positions were close to neutral at IC, and only minor knee angular changes occurred later in the sequences. The mean hip flexion was 25° (range, 8°-43°) at IC and increased by 22° (95% CI, 11°-32°) after 100 ms. The hip was also externally rotated by 7° (range, −19° to 3°) at IC, and gradually rotated internally, reaching 10° of internal rotation (range, −5° to 27°) at 100 ms after IC. This study suggests that the observed knee valgus, internal hip and knee rotation, and static hip flexion previously reported in non-contact ACL injury events are unique to injury situations. In contrast, neither rapid knee valgus nor increased internal rotation was seen in non-injury pressing maneuvers.

• Steenstrup, Sophie E.; Mok, Kam-Ming; McIntosh, Andrew S.; Bahr, Roald & Krosshaug, Tron (2018). Reconstruction of head impacts in FIS World Cup alpine skiing. British Journal of Sports Medicine. ISSN 0306-3674. 52(11), p. 709–715. doi: 10.1136/bjsports-2017-098050. Show summary

  Introduction: Prior to the 2013/2014 season, the International Ski Federation (FIS) increased the helmet testing speed from 5.4 to 6.8m/s for alpine downhill, super-G and giant slalom. Whether this increased testing speed reflects head impact velocities in real head injury situations on snow is unclear. We therefore investigated the injury mechanisms and gross head impact biomechanics in seven real head injury situations among World Cup (WC) alpine skiers. Methods: We analysed nine head impacts from seven head injury videos from the FIS Injury Surveillance System, throughout nine WC seasons (2006–2015) in detail. We used commercial video-based motion analysis software to estimate head impact kinematics in two dimensions, including directly preimpact and postimpact, from broadcast video. The sagittal plane angular movement of the head was also measured using angle measurement software. Results: In seven of nine head impacts, the estimated normal to slope preimpact velocity was higher than the current FIS helmet rule of 6.8m/s (mean 8.1 (±SD 0.6) m/s, range 1.9±0.8 to 12.1±0.4m/s). The nine head impacts had a mean normal to slope velocity change of 9.3±1.0m/s, range 5.2±1.1 to 13.5±1.3m/s. There was a large change in sagittal plane angular velocity (mean 43.3±2.9 rad/s (range 21.2±1.5 to 64.2±3.0 rad/s)) during impact. Conclusion: The estimated normal to slope preimpact velocity was higher than the current FIS helmet rule of 6.8m/s in seven of nine head impacts.

• Tierney, Gregory; Joodaki, Hamed; Krosshaug, Tron; Forman, Jason L.; Crandall, Jeff R. & Simms, Ciaran (2018). Assessment of model-based image-matching for future reconstruction of unhelmeted sport head impact kinematics. Sports Biomechanics. ISSN 1476-3141. 17(1), p. 33–47. doi: 10.1080/14763141.2016.1271905. Full text in Research Archive Show summary

  Player-to-player contact inherent in many unhelmeted sports means that head impacts are a frequent occurrence. Model-Based Image-Matching (MBIM) provides a technique for the assessment of three-dimensional linear and rotational motion patterns from multiple camera views of a head impact event, but the accuracy is unknown for this application. The goal of this study is to assess the accuracy of the MBIM method relative to reflective marker-based motion analysis data for estimating six degree of freedom head displacements and velocities in a staged pedestrian impact scenario at 40 km/h. Results showed RMS error was under 20 mm for all linear head displacements and 0.01–0.04 rad for head rotations. For velocities, the MBIM method yielded RMS errors between 0.42 and 1.29 m/s for head linear velocities and 3.53–5.38 rad/s for angular velocities. This method is thus beneficial as a tool to directly measure six degree of freedom head positional data from video of sporting head impacts, but velocity data is less reliable. MBIM data, combined in future with velocity/acceleration data from wearable sensors could be used to provide input conditions and evaluate the outputs of multibody and finite element head models for brain injury assessment of sporting head impacts.

• Mok, Kam-Ming; Bahr, Roald & Krosshaug, Tron (2018). Reliability of lower limb biomechanics in two sport-specific sidestep cutting tasks. Sports Biomechanics. ISSN 1476-3141. 17(2), p. 157–167. doi: 10.1080/14763141.2016.1260766. Full text in Research Archive Show summary

  The purpose of this study was to assess the within- and between-session reliability of lower limb biomechanics in two sport-specific sidestep cutting tasks performed by elite female handball and football (soccer) athletes. Moreover, we aimed at determining the minimum number of trials necessary to obtain a reliable measure. Nineteen elite female handball and 22 elite female football (soccer) athletes (M ± SD: 22 ± 4 yrs old, 168 ± 5 cm, 66 ± 8 kg) were tested. The reliability was quantified by intra-class correlations (ICCs), typical error and Spearman’s rank correlation. Only minor improvements in ICC values were seen when increasing the number of trials from 3 to 5. Based on trials 1–3, all variables showed good to excellent within-session reliability (M ICC: 0.91, 95% CI: 0.89–0.93), fair to good between-session reliability (M ICC: 0.73, 95% CI: 0.70–0.76), moderately positive between-session rank correlation coefficients (M: 0.72, 95% CI: 0.69–0.76). A few frontal plane biomechanical variables displayed lower between-session reliability in the football task compared with the handball task. The moderately positive between-session ranking and practically small typical error implies that the measurements could reliably reproduce the ranking of individuals in multiple-session studies. Adequate reliability could be attained from 3 trials, with only minor improvements when adding more trials.

• Koga, Hideyuki; Nakamae, Atsuo; Shima, Yosuke; Bahr, Roald & Krosshaug, Tron (2018). Hip and Ankle Kinematics in Noncontact Anterior Cruciate Ligament Injury Situations : Video Analysis Using Model-Based Image Matching. American Journal of Sports Medicine. ISSN 0363-5465. 46(2), p. 333–340. doi: 10.1177/0363546517732750. Show summary

  Background: Detailed kinematic descriptions of real anterior cruciate ligament (ACL) injury situations are limited to the knee only. Purpose: To describe hip and ankle kinematics as well as foot position relative to the center of mass (COM) in ACL injury situations through use of a model-based image-matching (MBIM) technique. The distance between the projection of the COM on the ground and the base of support (BOS) (COM_BOS) normalized to the femur length was also evaluated. Study Design: Descriptive laboratory study. Methods: Ten ACL injury video sequences from women’s handball and basketball were analyzed. Hip and ankle joint kinematic values were obtained by use of MBIM. Results: The mean hip flexion angle was 51° (95% CI, 41° to 63°) at initial contact and remained constant over the next 40 milliseconds. The hip was internally rotated 29° (95% CI, 18° to 39°) at initial contact and remained unchanged for the next 40 milliseconds. All of the injured patients landed with a heel strike with a mean dorsiflexion angle of 2° (95% CI, –9° to 14°), before reaching a flatfooted position 20 milliseconds later. The foot position was anterior and lateral to the COM in all cases. However, none of the results showed larger COM_BOS than 1.2, which has been suggested as a criterion for ACL injury risk. Conclusions: Hip kinematic values were consistent among the 10 ACL injury situations analyzed; the hip joint remained unchanged in a flexed and internally rotated position in the phase leading up to injury, suggesting that limited energy absorption took place at the hip. In all cases, the foot contacted the ground with the heel strike. However, relatively small COM_BOS distances were found, indicating that the anterior and lateral foot placement in ACL injury situations was not different from what can be expected in noninjury game situations.

• Koga, Hideyuki; Muneta, Takeshi; Bahr, Roald; Engebretsen, Lars & Krosshaug, Tron (2017). ACL injury mechanisms : lessons learned from video analysis. In Musahl, Volker; Karlsson, Jón; Kuroda, Ryosuke & Zaffagnini, Stefano (Ed.), Rotary knee instability : an evidence based approach. Springer. ISSN 978-3-319-32069-4. p. 27–36. doi: 10.1007/978-3-319-32070_3.
• Leppänen, Mari; Pasanen, Kati; Krosshaug, Tron; Kannus, Pekka; Vasankari, Tommi & Kujala, Urho M [Show all 9 contributors for this article] (2017). Sagittal Plane Hip, Knee, and Ankle Biomechanics and the Risk of Anterior Cruciate Ligament Injury :A Prospective Study. Orthopaedic Journal of Sports Medicine (OJSM). ISSN 2325-9671. 5(12). doi: 10.1177/2325967117745487. Full text in Research Archive
• Steenstrup, Sophie E.; Mok, Kam-Ming; McIntosh, Andrew S.; Bahr, Roald & Krosshaug, Tron (2017). Head impact velocities in FIS World Cup snowboarders and freestyle skiers: Do real-life impacts exceed helmet testing standards? British Journal of Sports Medicine. ISSN 0306-3674. doi: 10.1136/bjsports-2016-097086. Show summary

  Introduction: Prior to the 2013–2014 season, the International Ski Federation (FIS) increased the helmet testing speed from a minimum requirement of 5.4 to 6.8 m/s for alpine downhill, super-G and giant slalom and for freestyle ski cross, but not for the other freestyle disciplines or snowboarding. Whether this increased testing speed reflects impact velocities in real head injury situations on snow is unclear. We therefore investigated the injury mechanisms and gross head impact biomechanics in four real head injury situations among World Cup (WC) snowboard and freestyle athletes and compared these with helmet homologation laboratory test requirements. The helmets in the four cases complied with at least European Standards (EN) 1077 (Class B) or American Society for Testing and Materials (ASTM) F2040. Methods: We analysed four head injury videos from the FIS Injury Surveillance System throughout eight WC seasons (2006–2014) in detail. We used motion analysis software to digitize the helmet’s trajectory and estimated the head’s kinematics in two dimensions, including directly preimpact and postimpact. Results: All four impacts were to the occiput. In the four cases, the normal-to-slope preimpact velocity ranged from 7.0(±SD 0.2) m/s to 10.5±0.5 m/s and the normal-to-slope velocity change ranged from 8.4±0.6 m/s to 11.7±0.7 m/s. The sagittal plane helmet angular velocity estimates indicated a large change in angular velocity (25.0±2.9 rad/s to 49.1±0.3 rad/s). Conclusion: The estimated normal-to-slope preimpact velocity was higher than the current strictest helmet testing rule of 6.8 m/s in all four cases.

• Steffen, Kathrin; Nilstad, Agnethe; Krosshaug, Tron; Pasanen, Kati; Killingmo, Aleksander & Bahr, Roald (2017). No association between static and dynamic postural control and ACL injury risk among female elite handball and football players: a prospective study of 838 players. British Journal of Sports Medicine. ISSN 0306-3674. 51(4), p. 253–259. doi: 10.1136/bjsports-2016-097068. Show summary

  Background: Research on balance measures as potential risk factors for ACL injury is limited. Objective: To assess whether postural control was associated with an increased risk for ACL injuries in female elite handball and football players. Method: Premier league players were tested in the preseason and followed prospectively for ACL injury risk from 2007 through 2015. At baseline, we recorded player demographics, playing experience, ACL and ankle injury history. We measured centre of pressure velocity in single-leg stabilisation tests and reach distances in the Star Excursion Balance Test. To examine the stability of postural control measures over time, we examined their short-term and long-term reproducibility. We generated logistic regression models, 1 for each of the proposed risk factors. Results: A total of 55 (6.6%) out of 838 players (age 21±4 years; height 170±6 cm; body mass 66±8 kg) sustained a non-contact ACL injury after baseline testing (1.8±1.8 years). When comparing normalised balance measures between injured and uninjured players in univariate analyses, none of the variables were statistically associated with ACL injury risk. Short-term and long-term reproducibility of the selected variables was poor. Players with a previous ACL injury had a 3-fold higher risk of sustaining a new ACL injury compared with previously uninjured players (OR 2.9, CI 1.4 to 5.7). Conclusions: None of postural control measures examined were associated with increased ACL injury risk among female elite handball and football players. Hence, as measured in the current investigation, the variables included cannot be used to predict ACL injury risk.

• Leppänen, Mari; Pasanen, Kati; Kujala, Urho M; Vasankari, Tommi; Kannus, Pekka & Äyrämö, Sami [Show all 11 contributors for this article] (2017). Stiff Landings Are Associated with Increased ACL Injury Risk in Young Female Basketball and Floorball Players. American Journal of Sports Medicine. ISSN 0363-5465. 45(2), p. 386–393. doi: 10.1177/0363546516665810. Show summary

  Background: Few prospective studies have investigated the biomechanical risk factors of anterior cruciate ligament (ACL) injury. Purpose: To investigate the relationship between biomechanical characteristics of vertical drop jump (VDJ) performance and the risk of ACL injury in young female basketball and floorball players. Study Design: Cohort study; Level of evidence, 3. Methods: At baseline, a total of 171 female basketball and floorball players (age range, 12-21 years) participated in a VDJ test using 3-dimensional motion analysis. The following biomechanical variables were analyzed: (1) knee valgus angle at initial contact (IC), (2) peak knee abduction moment, (3) knee flexion angle at IC, (4) peak knee flexion angle, (5) peak vertical ground-reaction force (vGRF), and (6) medial knee displacement. All new ACL injuries, as well as match and training exposure, were then recorded for 1 to 3 years. Cox regression models were used to calculate hazard ratios (HRs) and 95% CIs. Results: Fifteen new ACL injuries occurred during the study period (0.2 injuries/1000 player-hours). Of the 6 factors considered, lower peak knee flexion angle (HR for each 10 increase in knee flexion angle, 0.55; 95% CI, 0.34-0.88) and higher peak vGRF (HR for each 100-N increase in vGRF, 1.26; 95% CI, 1.09-1.45) were the only factors associated with increased risk of ACL injury. A receiver operating characteristic (ROC) curve analysis showed an area under the curve of 0.6 for peak knee flexion and 0.7 for vGRF, indicating a failed-to-fair combined sensitivity and specificity of the test. Conclusions: Stiff landings, with less knee flexion and greater vGRF, in a VDJ test were associated with increased risk of ACL injury among young female basketball and floorball players. However, although 2 factors (decreased peak knee flexion and increased vGRF) had significant associations with ACL injury risk, the ROC curve analyses revealed that these variables cannot be used for screening of athletes.

• Mok, Kam-Ming; Bahr, Roald & Krosshaug, Tron (2017). The effect of overhead target on the lower limb biomechanics during a vertical drop jump test in elite female athletes. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. 27(2), p. 161–166. doi: 10.1111/sms.12640. Show summary

  The purpose of the study was to investigate the effect of anoverhead target on the jump height and lower limbbiomechanics in all three planes of motion in a verticaldrop jump (VDJ) task among elite female handball andfootball (soccer) players. The hypothesis was that addingan overhead target to the VDJ task improves jump height,increases joint loading, and decreases frontal plane kneecontrol. Five hundred and twenty-three female handballand football players (mean  SD: 21  4 years,168  6 cm, 65  8 kg) completed the test. The overheadtarget increased jumping height by 5.8%. Furthermore, theoverhead target led to statistically significant changes inmany of the lower limb biomechanical variables examined.However, all the changes in kinematics and kinetics wereclinically insignificant, as indicated by the small effectsizes. Strong to moderate positive Spearman’s rankcorrelations were found between the two conditions.Therefore, an overhead target is unlikely to increase therange of responses in biomechanical variables in elitefemale handball and football athletes.

View all works in Cristin

• Krosshaug, Tron (2024). Does your exercise target the muscles you think you’re targetting? (linked workshop).
• Krosshaug, Tron (2024). Translating biomechanics theory to practice - understand the exercises so you can design the best resistance training programs.
• Eriksrud, Ola; Krosshaug, Tron; Mai, Patrick; Glørsen, Øyvind & Westheim, Frederic (2024). Deceleration demands in change of direction tests: insights from measurements using a motorized resistance device .
• Vander Vleuten, Reid; Wannop, John; Van den Berg, Carla; Critchley, Meghan; Jordan, Matthew & Krosshaug, Tron [Show all 7 contributors for this article] (2024). Knee Kinematics and Kinetics During Sport-Specific Cutting and Landing Maneuvers in Female University Soccer Players: Implications for ACL Injury Prevention .
• Kamatsuki, Yusuke; Qvale, Marie Synnøve; Wangensteen, Arnlaug; Steffen, Kathrin & Krosshaug, Tron (2024). Anatomical risk factors for primary and secondary non-contact ACL injury – a prospective cohort study in 880 female elite players.
• Bill, Kevin; Mai, Patrick; Krosshaug, Tron; Mausehund, Lasse & Kersting, Uwe (2024). Individualized Sidestep Cutting Technique Feedback in Handball Under Consideration of Performance - Best of Both Worlds for ACL Injury Prevention?
• Mausehund, Lasse; Patron, Anri; Äyrämö, Sami & Krosshaug, Tron (2024). Cluster analysis of cutting technique: A valuable approach for assessing anterior cruciate ligament injury risk?
• Mai, Patrick; Bill, Kevin; Kersting, Uwe; Willwacher, Steffen; Eriksrud, Ola & Krosshaug, Tron (2024). A nine-week ACL injury prevention program for female handball players: Effect on knee joint loading and cutting technique during a handball-specific fake-cut.
• Krosshaug, Tron (2024). Immediate feedback on technique and loading parameters to make cutting movements safer.
• Krosshaug, Tron (2023). Does your exercise target the muscles you think you’re targetting?
• Krosshaug, Tron (2023). Translating biomechanics theory to practice: understand the exercises so you can design the best resistance training programs.
• Mausehund, Lasse & Krosshaug, Tron (2023). Cluster analysis of cutting technique - A valuable approach for assessing ACL injury risk?
• Krosshaug, Tron (2023). Cluster analysis of cutting technique - A valuable approach for assessing ACL injury risk?
• Gjestvang, Christina; Krosshaug, Tron & Haakstad, Lene (2023). Hvorfor vil staten gjøre det dyrere å trene? Aftenposten (morgenutg. : trykt utg.). ISSN 0804-3116.
• Krosshaug, Tron (2022). ACL injury mechanisms and biomechanical risk factors.
• Krosshaug, Tron (2022). ACL injury mechanisms and biomechanical risk factors.
• Krosshaug, Tron (2022). Hva har vi lært av 20 års forskning på ACL-skader? Et dypdykk i skademekanismer og risikofaktorer med hovedfokus på biomekanikk/bevegelsesanalyse .
• Bill, Kevin; Mai, Patrick; Robertz, Leon; Glöckler, Katharina; Claramunt-Molet, Mireia & Bartsch, Julia [Show all 14 contributors for this article] (2022). Knee kinematics and kinetics of sport-specific fake-and-cut maneuvers of varying complexity in female handball players.
• Mai, Patrick; Bill, Kevin; Robertz, Leon; Glöckler, Katharina; Claramunt-Molet, Mireia & Bartsch, Julia [Show all 15 contributors for this article] (2022). Can a simplified knee abduction moment estimation be used for athlete screening? Implications for ACL injury prevention.
• Mai, Patrick; Bill, Kevin; Bartsch, Julia; Willwacher, Steffen; Kersting, Uwe & Krosshaug, Tron (2022). Screening athletes for ACL injury risk - effects of game specificity on knee abduction moment.
• Mausehund, Lasse & Krosshaug, Tron (2022). Why are players with a previous ACL injury at elevated risk of sustaining a new secondary ACL injury?
• Mai, Patrick; Bill, Kevin; Gloeckler, Katharina & Krosshaug, Tron (2021). Mimicking game scenarios in a laboratory-based environment - the effects on knee abduction moment when facing varied task demands.
• Bill, Kevin; Mai, Patrick; Molet, Claramunt & Krosshaug, Tron (2021). The effect of cutting task complexity on technique variables associated with increased risk of ACL injuries in female handball players.
• Krosshaug, Tron (2021). Biomechanics of cutting and landing – injury mechanisms and risk factors for ACL injury.
• Solstad, Tom Erik Jorung; Krosshaug, Tron; Mausehund, Lasse; van den Tillaar, Roland Johannes Wilhelmus; Larsen, Stian & Samnøy, Lars Edvin [Show all 7 contributors for this article] (2021). Episode 50 - Rundbordsprat om øvelsen benkpress. [Internet]. Idrettsforskning .
• Leppänen, Mari; Parkkari, Jari; Vasankari, Tommi; Äyrämö, Sami; Krosshaug, Tron & Kannus, Pekka [Show all 7 contributors for this article] (2021). Change of direction biomechanics and the risk for non-contact knee injuries in youth basketball and floorball players . British Journal of Sports Medicine. ISSN 0306-3674. 55, p. A17–A18. doi: 10.1136/bjsports-2021-IOC.40.
• Leppänen, Mari; Parkkari, Jari; Vasankari, Tommi; Äyrämö, Sami; Krosshaug, Tron & Kannus, Pekka [Show all 7 contributors for this article] (2021). Change of direction biomechanics and the risk for non contact knee injuries in youth basketball and floorball players.
• Krosshaug, Tron (2021). Taking it to the next level. Sophisticated 3D animations for injury prevention delivery.
• Krosshaug, Tron (2021). Introduction.
• Krosshaug, Tron (2021). Taking knee and hip biomechanics measurements from the lab to the field: Is it possible?
• Nilstad, Agnethe; Petushek, Erich; Mok, Kam-Ming; Bahr, Roald & Krosshaug, Tron (2021). Response to letter to the editor about ‘kiss goodbye to the “kissing knees”: no association between frontal plane inward knee motion and risk of future non-contact ACL injury in elite female athletes’. Sports Biomechanics. ISSN 1476-3141. doi: 10.1080/14763141.2021.1983637.
• Krosshaug, Tron (2021). Animasjonsbasert undervisning i styrketrening og biomekanikk.
• Bahr, Roald & Krosshaug, Tron (2020). The Oslo Sports Trauma Research Center (OSTRC).
• Krosshaug, Tron (2020). Prospective ACL risk factor studies of landing and cutting biomechanics – what have we learnt after 15 years of research.
• Krosshaug, Tron (2020). Is cutting technique a risk factor for ACL injury? .
• Strand, Jørn Erik; Nilstad, Agnethe & Krosshaug, Tron (2019). Knekontroll i frontalplanet under en ett-bens knebøy er ikke assosiert med økt risiko for fremre korsbåndskade.
• Krosshaug, Tron (2018). STYRKETRÄNING OCH BIOMEKANIK, teori & praktik.
• Räisänen, Anu; Pasanen, Kati; Krosshaug, Tron; Vasankari, Tommi; Kannus, Pekka & Heinonen, A. [Show all 9 contributors for this article] (2018). Association between frontal plane knee control and lower extremity injuries: a prospective study on young team sport athletes.
• Thorarinsdottir, Solveig & Krosshaug, Tron (2018). Association between lower extremity strength and knee and pelvic kinematics during a single leg squat.
• Krosshaug, Tron (2018). Video analysis of elite skiing injury mechanisms.
• Leppänen, Mari; Pasanen, Kati; Kujala, Urho M; Vasankari, Tommi; Kannus, Pekka & Äyrämö, Sami [Show all 11 contributors for this article] (2017). Stiff Landings Are Associated With Increased ACL Injury Risk in Young Female Basketball and Floorball Players: Response. American Journal of Sports Medicine. ISSN 0363-5465. 45(3), p. np5–np6. doi: 10.1177/0363546517692762.
• Krosshaug, Tron (2017). ACL mechanism of injury.
• McIntosh, Andrew & Krosshaug, Tron (2017). Workshop: Orienting biomechanics research for sports injury prevention -.
• Sasaki, Shogo; Koga, Hideyuki; Krosshaug, Tron & Fukubayashi, Toru (2017). Kinematic analysis of pressing movements in women's soccer competitions. British Journal of Sports Medicine. ISSN 0306-3674. 51(4).
• Sasaki, Shogo; Koga, Hideyuki; Krosshaug, Tron & Fukubayashi, Toru (2017). Kinematic analysis of pressing movements in women's soccer competitions.
• Räisänen, Anu; Pasanen, Kati; Krosshaug, Tron; Kannus, Pekka; Vasankari, Tommi & Parkkari, Jari (2017). Association between Frontal Plane Knee Control and Acute Lowe Extremity Injuries. British Journal of Sports Medicine. ISSN 0306-3674. 51(4), p. 375–376.
• Räisänen, Anu; Pasanen, Kati; Krosshaug, Tron; Kannus, Pekka; Vasankari, Tommi & Parkkari, Jari (2017). Association between Frontal Plane Knee Control and Acute Lowe Extremity Injuries.
• Leppänen, Mari; Pasanen, Kati; Krosshaug, Tron; Kannus, Pekka; Vasankari, Tommi & Parkkari, Jari (2017). Landing with less hip flexion is associated with increased risk of ACL injuries in young female team sports players. British Journal of Sports Medicine. ISSN 0306-3674. 51(4).
• Leppänen, Mari; Pasanen, Kati; Krosshaug, Tron; Kannus, Pekka; Vasankari, Tommi & Parkkari, Jari (2017). Landing with less hip flexion is associated with increased risk of ACL injuries in young female team sports players.
• Steffen, Kathrin; Nilstad, Agnethe; Krosshaug, Tron; Pasanen, Kati & Bahr, Roald (2017). No association between static and dynamic postural control and ACL injury risk among female elite handball and football players. British Journal of Sports Medicine. ISSN 0306-3674. 51(4).
• Steffen, Kathrin; Nilstad, Agnethe; Krosshaug, Tron; Pasanen, Kati & Bahr, Roald (2017). No association between static and dynamic postural control and ACL injury risk among female elite handball and football players.
• Krosshaug, Tron; Pasanen, Kati; Steffen, Kathrin; Mok, Kam-Ming; Bencke, Jesper & Zebis, Mette (2017). Panel discussion: How do we improve current ACL injury prevention programs?
• Krosshaug, Tron (2017). What have we learned from biomechanical analyses of ACL injury videos?
• Steenstrup, Sophie E.; Bere, Tone Tufte; Krosshaug, Tron; Nordsletten, Lars & Bahr, Roald (2016). FIS Injury Surveillance System, 2016 Injury Statistics update. FIS Medical Committee.
• Krosshaug, Tron & Bartsch, Julia (2022). Comparing Knee Loading in Anticipated and Unanticipated Handball Specific Cutting Tasks and Generic 180-Degree-Change-of-Direction Master Thesis. University of Konstanz.
• Krosshaug, Tron & Eggerud, Mathias Midthjell (2022). Muscle activation of thigh muscles in predetermined and randomized cutting directions during side-cut faking tasks among female handball athletes - a cross-sectional study. Norges idrettshøgskole.
• Krosshaug, Tron & Flathus, Mona Holtan (2022). Fordeling av leddmomenter mellom albue- og skulderledd ved seks ulike varianter av push-ups med ulike hånd- og albueposisjoner. Norges idrettshøgskole.
• Krosshaug, Tron & Mo, Helena Cecilie (2022). Biomechanical analysis of groin related strength training exercises for injury prevention. Universitetet i Bergen.
• Kaardal, Tarjei & Krosshaug, Tron (2019). Comparing the effects of different variants of the free weight barbell squat to machine-based squatting exercises - a systematic literature review. Norges idrettshøgskole.
• Strand, Jørn Erik; Krosshaug, Tron & Nilstad, Agnethe (2019). Er knekontroll i frontalplanet under en ettbens knebøy assosiert med økt risiko for fremre korsbåndskade En todimensjonal (2D) videoanalyse av kvinnelige eliteutøvere i håndball og fotball . Norges idrettshøgskole.
• Christensen, Camilla; Krosshaug, Tron & Nilstad, Agnethe (2019). Samsvar mellom knekontroll i frontalplanet ved ettbens knebøy og tobens fallhopp En todimensjonal (2D) videoanalyse av kvinnelige elite håndball- og fotballspillere . Norges idrettshøgskole.
• Krosshaug, Tron & Flatsetøy, Hanne (2018). Effekten av en treningsintervensjon på muskelstyrke og kroppsammensetning hos lungetransplanterte pasienter. En randomisert kontrollert studie, HILT . Norges idrettshøgskole.
• Krosshaug, Tron & Thorarinsdottir, Solveig (2018). Association between maximal hip and knee strength and frontal plane projection angle, medial knee displacement and lateral pelvic tilt during a single leg squat. A two dimensional (2D) video analysis of elite female football players. Norges idrettshøgskole.

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