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Wochner I, Nölle LV, Martynenko OV, Schmitt S. ‘Falling heads’: investigating reflexive responses to head–neck perturbations. Biomed Eng Online 2022; 21:25. [PMID: 35429975 PMCID: PMC9013062 DOI: 10.1186/s12938-022-00994-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 03/29/2022] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
Reflexive responses to head–neck perturbations affect the injury risk in many different situations ranging from sports-related impact to car accident scenarios. Although several experiments have been conducted to investigate these head–neck responses to various perturbations, it is still unclear why and how individuals react differently and what the implications of these different responses across subjects on the potential injuries might be. Therefore, we see a need for both experimental data and biophysically valid computational Human Body Models with bio-inspired muscle control strategies to understand individual reflex responses better.
Methods
To address this issue, we conducted perturbation experiments of the head–neck complex and used this data to examine control strategies in a simulation model. In the experiments, which we call ’falling heads’ experiments, volunteers were placed in a supine and a prone position on a table with an additional trapdoor supporting the head. This trapdoor was suddenly released, leading to a free-fall movement of the head until reflexive responses of muscles stopped the downwards movement.
Results
We analysed the kinematic, neuronal and dynamic responses for all individuals and show their differences for separate age and sex groups. We show that these results can be used to validate two simple reflex controllers which are able to predict human biophysical movement and modulate the response necessary to represent a large variability of participants.
Conclusions
We present characteristic parameters such as joint stiffness, peak accelerations and latency times. Based on this data, we show that there is a large difference in the individual reflexive responses between participants. Furthermore, we show that the perturbation direction (supine vs. prone) significantly influences the measured kinematic quantities. Finally, ’falling heads’ experiments data are provided open-source to be used as a benchmark test to compare different muscle control strategies and to validate existing active Human Body Models directly.
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Farley T, Barry E, Sylvester R, Medici AD, Wilson MG. Poor isometric neck extension strength as a risk factor for concussion in male professional Rugby Union players. Br J Sports Med 2022; 56:616-621. [PMID: 35197247 DOI: 10.1136/bjsports-2021-104414] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/02/2022] [Indexed: 01/26/2023]
Abstract
BACKGROUND Concussion is one of the highest burden injuries within professional Rugby Union ('rugby') and comes with a high health and financial cost to players and teams. Limited evidence exists as to the existence of modifiable intrinsic risk factors for concussion, leaving athletes and clinicians with few options when developing prevention strategies. OBJECTIVE To investigate whether neck strength is significantly associated with concussion incidence in professional male rugby players. METHODS 225 rugby players were assessed for neck strength at three time points throughout the 2018/2019 season using a method of isometric contraction. Associations with clinically diagnosed concussion injuries are presented as incidence rate ratios (IRRs) with 95% CIs. RESULTS Thirty concussions occurred in 29 players during the study period; a rate of 13.7 concussions per 1000 hours played. Greater neck strength was observed at mid and end of season time points versus preseason across the study population. There was a significant association between extension strength and concussion; a 10% increase for extension strength was associated with a 13% reduction in concussion rate (adjusted IRR (95% CI) 0.87 (0.78 to 0.98). No other significant associations were observed between concussion incidence and any other unique neck strength range or composite score. CONCLUSION Higher neck extension strength is associated with lower concussion rates in male rugby players. Neck strength is a modifiable intrinsic risk factor for concussion and may be an important component of a strength and conditioning regime.
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Affiliation(s)
- Theo Farley
- Division of Surgery and Interventional Science, University College London, London, UK .,Institute of Sport, Exercise and Health (ISEH), University College London, London, London, UK
| | - Ed Barry
- Georgia Rugby Federation, Tbilisi, Georgia
| | - Richard Sylvester
- Institute of Sport, Exercise and Health (ISEH), University College London, London, London, UK.,National Hospital for Neurology and Neurosurgery, London, UK
| | - Akbar De Medici
- Institute of Sport, Exercise and Health (ISEH), University College London, London, London, UK
| | - Mathew G Wilson
- Division of Surgery and Interventional Science, University College London, London, UK.,Institute of Sport, Exercise and Health (ISEH), University College London, London, London, UK
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Fanton M, Kuo C, Sganga J, Hernandez F, Camarillo DB. Dependency of Head Impact Rotation on Head-Neck Positioning and Soft Tissue Forces. IEEE Trans Biomed Eng 2019; 66:988-999. [DOI: 10.1109/tbme.2018.2866147] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Kuo C, Fanton M, Wu L, Camarillo D. Spinal constraint modulates head instantaneous center of rotation and dictates head angular motion. J Biomech 2018; 76:220-228. [PMID: 29929891 DOI: 10.1016/j.jbiomech.2018.05.024] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 05/23/2018] [Accepted: 05/30/2018] [Indexed: 11/19/2022]
Abstract
The head is kinematically constrained to the torso through the spine and thus, the spine dictates the amount of output head angular motion expected from an input impact. Here, we investigate the spinal kinematic constraint by analyzing the head instantaneous center of rotation (HICOR) with respect to the torso in head/neck sagittal extension and coronal lateral flexion during mild loads applied to 10 subjects. We found the mean HICOR location was near the C5-C6 intervertebral joint in sagittal extension, and T2-T3 intervertebral joint in coronal lateral flexion. Using the impulse-momentum relationship normalized by subject mass and neck length, we developed a non-dimensional analytical ratio between output angular velocity and input linear impulse as a function of HICOR location. The ratio was 0.65 and 0.50 in sagittal extension and coronal lateral flexion respectively, implying 30% greater angular velocities in sagittal extension given an equivalent impulse. Scaling to subject physiology also predicts larger required impulses given greater subject mass and neck length to achieve equivalent angular velocities, which was observed experimentally. Furthermore, the HICOR has greater motion in sagittal extension than coronal lateral flexion, suggesting the head and spine can be represented with a single inverted pendulum in coronal lateral flexion, but requires a more complex representation in sagittal extension. The upper cervical spine has substantial compliance in sagittal extension, and may be responsible for the complex motion and greater extension angular velocities. In analyzing the HICOR, we can gain intuition regarding the neck's role in dictating head motion during external loading.
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Affiliation(s)
- Calvin Kuo
- Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA.
| | - Michael Fanton
- Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Lyndia Wu
- Department of Biomechanical Engineering, Stanford University, Stanford, CA 94305, USA
| | - David Camarillo
- Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA; Department of Biomechanical Engineering, Stanford University, Stanford, CA 94305, USA
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Portero R, Quaine F, Cahouet V, Léouffre M, Servière C, Portero P. Influence of Cervical Muscle Fatigue on Musculo-Tendinous Stiffness of the Head-Neck Segment during Cervical Flexion. PLoS One 2015; 10:e0139333. [PMID: 26418000 PMCID: PMC4587888 DOI: 10.1371/journal.pone.0139333] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 09/11/2015] [Indexed: 11/22/2022] Open
Abstract
AIM The aim of this study is to determine if the fatigue of cervical muscles has a significant influence on the head-neck segment musculo-tendinous stiffness. METHODS Ten men (aged 21.2 ± 1.9 years) performed four quick-release trials of flexion at 30 and 50% MVC before and after the induction of muscular fatigue on cervical flexors. Electromyographic activity was recorded on the sternocleidomastoids (SCM) and spinal erectors (SE), bilaterally. Musculo-tendinous stiffness was calculated through the quick-release method adapted to the head-neck segment. RESULTS We noticed a significant linear increase of the head-neck segment musculo-tendinous stiffness with the increase of exertion level both before (P < 0.0001) and after the fatigue procedure (P < 0.0001). However, this linear relationship was not different before and after the fatigue procedure. EMG analysis revealed a significant increase of the root mean square for the right SCM (P = 0.0002), the left SCM (P < 0.0001), the right SE (P < 0.0001), and the left SE (P < 0.0001) and a significant decrease of the median power frequency only for the right (P = 0.0006) and the left (P = 0.0003) SCM with muscular fatigue. DISCUSSION We did not find significant changes in the head-neck segment musculo-tendinous stiffness with fatigue of cervical muscles. We found a significant increase in EMG activity in the SCM and the SE after the induction of fatigue of the SCM. Our findings suggest that with fatigue of cervical flexors, neck muscle activity is modulated in order to maintain the musculo-tendinous stiffness at a steady state.
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Affiliation(s)
- Raphaël Portero
- Département d’Automatique, GIPSA Lab, UMR CNRS 5216, Université Joseph Fourier, Grenoble, France
- Service de Rééducation Neuro-Orthopédique, Hôpital Rothschild (AP—HP), Paris, France
| | - Franck Quaine
- Département d’Automatique, GIPSA Lab, UMR CNRS 5216, Université Joseph Fourier, Grenoble, France
| | - Violaine Cahouet
- Département d’Automatique, GIPSA Lab, UMR CNRS 5216, Université Joseph Fourier, Grenoble, France
| | - Marc Léouffre
- Département d’Automatique, GIPSA Lab, UMR CNRS 5216, Université Joseph Fourier, Grenoble, France
| | - Christine Servière
- Département d’Automatique, GIPSA Lab, UMR CNRS 5216, Université Joseph Fourier, Grenoble, France
| | - Pierre Portero
- Bioingénierie, Tissus et Neuroplasticité, EA 7377, Université Paris-Est, UPEC, Créteil, France
- Service de Rééducation Neuro-Orthopédique, Hôpital Rothschild (AP—HP), Paris, France
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Swaminathan R, Williams JM, Jones MD, Theobald PS. A kinematic analysis of the spine during rugby scrummaging on natural and synthetic turfs. J Sports Sci 2015; 34:1058-66. [PMID: 26375051 PMCID: PMC4784542 DOI: 10.1080/02640414.2015.1088165] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Artificial surfaces are now an established alternative to grass (natural) surfaces in rugby union. Little is known, however, about their potential to reduce injury. This study characterises the spinal kinematics of rugby union hookers during scrummaging on third-generation synthetic (3G) and natural pitches. The spine was sectioned into five segments, with inertial sensors providing three-dimensional kinematic data sampled at 40 Hz/sensor. Twenty-two adult, male community club and university-level hookers were recruited. An equal number were analysed whilst scrummaging on natural or synthetic turf. Players scrummaging on synthetic turf demonstrated less angular velocity in the lower thoracic spine for right and left lateral bending and right rotation. The general reduction in the range of motion and velocities, extrapolated over a prolonged playing career, may mean that the synthetic turf could result in fewer degenerative injuries. It should be noted, however, that this conclusion considers only the scrummaging scenario.
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Affiliation(s)
- Ramesh Swaminathan
- a Bioengineering Research Group, School of Engineering , Cardiff University , Cardiff , UK
| | - Jonathan M Williams
- b Faculty of Health and Social Sciences , Bournemouth University , Bournemouth , UK
| | - Michael D Jones
- a Bioengineering Research Group, School of Engineering , Cardiff University , Cardiff , UK
| | - Peter S Theobald
- a Bioengineering Research Group, School of Engineering , Cardiff University , Cardiff , UK
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Schmidt JD, Guskiewicz KM, Blackburn JT, Mihalik JP, Siegmund GP, Marshall SW. The influence of cervical muscle characteristics on head impact biomechanics in football. Am J Sports Med 2014; 42:2056-66. [PMID: 24928761 DOI: 10.1177/0363546514536685] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND An athlete is thought to reduce head acceleration after impact by contracting the cervical musculature, which increases the effective mass of the head. PURPOSE To compare the odds of sustaining higher magnitude in-season head impacts between athletes with higher and lower preseason performance on cervical muscle characteristics. STUDY DESIGN Cohort study; Level of evidence, 2. METHODS Forty-nine high school and collegiate American football players completed a preseason cervical testing protocol that included measures of cervical isometric strength, muscle size, and response to cervical perturbation. Head impact biomechanics were captured for each player using the Head Impact Telemetry System. A median split was used to categorize players as either high or low performers for each of the following outcome measures: isometric strength (peak torque, rate of torque development), muscle size (cross-sectional area), and response to cervical perturbation (stiffness, angular displacement, muscle onset latency). The odds of sustaining moderate and severe head impacts were computed against the reference odds of sustaining mild head impacts across cervical characteristic categorizations. RESULTS Linemen with stronger lateral flexors and composite cervical strength had about 1.75 times' increased odds of sustaining moderate linear head impacts rather than mild impacts compared with weaker linemen. Players who developed extensor torque more quickly had 2 times the increased odds of sustaining severe linear head impacts (odds ratio [OR], 2.10; 95% CI, 1.08-4.05) rather than mild head impacts. However, players with greater cervical stiffness had reduced odds of sustaining both moderate (OR, 0.77; 95% CI, 0.61-0.96) and severe (OR, 0.64; 95% CI, 0.46-0.89) head impacts compared with players with less cervical stiffness. CONCLUSION The study findings showed that greater cervical stiffness and less angular displacement after perturbation reduced the odds of sustaining higher magnitude head impacts; however, the findings did not show that players with stronger and larger neck muscles mitigate head impact severity.
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Affiliation(s)
| | - Kevin M Guskiewicz
- Matthew A. Gfeller Sport-Related Traumatic Brain Injury Research Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA Injury Prevention Research Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - J Troy Blackburn
- Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA Neuromuscular Research Laboratory, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Jason P Mihalik
- Matthew A. Gfeller Sport-Related Traumatic Brain Injury Research Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA Injury Prevention Research Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Gunter P Siegmund
- MEA Forensic Engineers & Scientists, Richmond, British Columbia, Canada School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Stephen W Marshall
- Injury Prevention Research Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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