No association between rate of torque development and onset of muscle activity with increased risk of hamstring injury in elite football
- Authors: van Dyk, Nicol , Bahr, Roald , Burnett, Angus , Verhagen, Evert , Von Tiggelen, D. , Witvrouw, Erik
- Date: 2018
- Type: Text , Journal article
- Relation: Scandinavian Journal of Medicine and Science in Sports Vol. 28, no. 10 (2018), p. 2153-2163
- Full Text: false
- Reviewed:
- Description: Hamstring injuries remain a significant burden in sports that involve high-speed running. In elite male football, hamstring injury has repeatedly been identified as the most common non-contact injury, representing 12% of all injuries. As the incidence remains high, investigations are aimed at better understanding how to improve prevention efforts. Intrinsic risk factors such as strength have been investigated extensively in a cohort of professional football players; however, other intrinsic measures of neuromuscular function have not been studied in this cohort. This study aims to investigate the association between timing of hamstring muscle activity onset and the rate of torque development during the early phase of isokinetic strength testing with risk of hamstring injury in professional football players in a prospective cohort study. All teams (n = 18) eligible to compete in the premier football league in Qatar underwent a comprehensive strength assessment during their annual periodic health evaluation at Aspetar Orthopaedic and Sports Medicine Hospital in Doha, Qatar. Variables included rate of torque development and timing of muscle activity onset. A total of 367 unique players (60.6% of all QSL players) competed for 514 player seasons (103 players competed both seasons) and sustained 65 hamstring injuries. There was no difference in the onset of muscle activity between the biceps femoris and medial hamstrings comparing the injured to uninjured players. For both onset of muscle activity and rate of torque development, there were no significant differences between any of the variables (P >.05), with small effect sizes detected across all the different variables (d < 0.3). Rate of torque development and onset of muscle activity were not associated with a risk of future hamstring injury. The use of these measures as part of a periodic health evaluation to identify risk of hamstring injury is unsupported.
A one-season prospective study of injuries and illness in elite junior tennis
- Authors: Pluim, Babette , Loeffen, F. , Clarsen, Ben , Bahr, Roald , Verhagen, Evert
- Date: 2016
- Type: Text , Journal article
- Relation: Scandinavian Journal of Medicine and Science in Sports Vol. 26, no. 5 (2016), p. 564-571
- Full Text: false
- Reviewed:
- Description: The objective of this study was to estimate the incidence and prevalence of injury and illness among elite junior tennis players. A cohort of 73 players (11-14 years) in the 2012-2013 Dutch national high-performance program was followed for 32 weeks; all participants completed the study. The OSTRC Questionnaire on Health Problems was used to record self-reported injuries and illnesses and to record training and match exposure. Main outcome measures were average prevalence of overuse injury and illness and incidence density of acute injury. On average, players practiced 9.1h/week (SD 0.6; range 2.3-12.0) and had 2.2h of match play (SD 0.6; range 2.3-12.0). During the course of the study, 67 players reported a total of 187 health problems. The average weekly prevalence of all health problems was 21.3% (95% CI: 19.2-22.9), of which 12.1% (95% CI: 10.9-13.3) constituted overuse injuries and 5.8% (95% CI: 4.6-6.9) illnesses. The incidence of acute injuries was 1.2/1000h of tennis play (95% CI: 0.7-1.7). The high occurrence of overuse injuries among elite junior tennis players suggests that an early focus on preventative measures is warranted, with a particular focus on the monitoring and management of workload. © 2016 John Wiley & Sons A/S.
Analysis of a severe head injury in World Cup alpine skiing
- Authors: Yamazaki, Junya , Gilgien, Matthias , Kleiven, Svein , McIntosh, Andrew , Nachbauer, Werner , Muller, Erich , Bere, Tone , Bahr, Roald , Krosshaug, Tron
- Date: 2015
- Type: Text , Journal article
- Relation: Medicine and Science in Sports and Exercise Vol. 47, no. 6 (2015), p. 1113-1118
- Full Text:
- Reviewed:
- Description: Traumatic brain injury (TBI) is the leading cause of death in alpine skiing. It has been found that helmet use can reduce the incidence of head injuries between 15% and 60%. However, knowledge on optimal helmet performance criteria in World Cup alpine skiing is currently limited owing to the lack of biomechanical data from real crash situations. Purpose: This study aimed to estimate impact velocities in a severe TBI case in World Cup alpine skiing. Methods: Video sequences from a TBI case in World Cup alpine skiing were analyzed using a model-based image matching technique. Video sequences from four camera views were obtained in full high-definition (1080p) format. A three-dimensional model of the course was built based on accurate measurements of piste landmarks and matched to the background video footage using the animation software Poser 4. A trunk-neck-head model was used for tracking the skier's trajectory. Results: Immediately before head impact, the downward velocity component was estimated to be 8 m.s(-1). After impact, the upward velocity was 3 m.s(-1), whereas the velocity parallel to the slope surface was reduced from 33 m.s(-1) to 22 m.s(-1). The frontal plane angular velocity of the head changed from 80 radIsj1 left tilt immediately before impact to 20 rad.s(-1) right tilt immediately after impact. Conclusions: A unique combination of high-definition video footage and accurate measurements of landmarks in the slope made possible a high-quality analysis of head impact velocity in a severe TBI case. The estimates can provide crucial information on how to prevent TBI through helmet performance criteria and design.