The Relationship Between Neck Strength and Sports-Related Concussion in Team Sports: A Systematic Review With Meta-analysis

Identifying Cervical Predictors of Recreational Mixed Martial Arts Participation: A Case-Control Study

Background: Recreational participation in Mixed Martial Arts (MMA) has rapidly increased. Despite consistent evidence of a high injury prevalence in MMA athletes, the neuromuscular implications of regular MMA training remain underexplored. The cervical spine is particularly vulnerable to trauma due to repetitive impacts and high mechanical demands in combat sports. Methods: This case-control study compared cervical spine function and self-reported symptoms between 25 recreational MMA athletes and 25 matched individuals who engaged in general fitness training. Outcome measures included Neck Disability Index (NDI), Post-Concussion Symptom Scale (PCSS), pain and headache reports, cervical range of motion (ROM), proprioception, isometric strength, and endurance. Multivariate logistic regression analysis was used to identify the predictors of group classification. Results: The MMA group exhibited significantly higher values for post-concussion symptoms (p = 0.012), cervical flexor endurance (p = 0.031), and the number of concussions (p = 0.001) but lower flexion ROM (p = 0.031). No significant differences were observed in strength, proprioception, or NDI scores. Logistic regression identified the number of concussions, age, total cervical ROM, and average rotation strength as significant predictors of group membership (model AUC = 0.96; Nagelkerke R2 = 0.797). Conclusions: Recreational MMA athletes demonstrated higher rates of concussion-related symptoms and reduced cervical flexion ROM than noncontact exercisers despite no statistically significant differences in strength and proprioception. These findings suggest that cumulative exposure to amateur MMA is associated with alterations in cervical neuromuscular characteristics. These results support the implementation of targeted mobility, endurance, and injury prevention programs in recreational MMA training.

Combining evidence and practice to optimise neck training aimed at reducing head acceleration events in sport: a systematic review and Delphi-consensus study

Head acceleration events (HAEs) can potentially have adverse consequences for athlete brain health. In sports, in which head injuries have the highest incidence, identifying strategies to reduce HAE frequency and magnitude is a priority. Neck training is a potential strategy to mitigate against the magnitude of HAEs. This two-part study aimed to (1) systematically review the literature of neck training interventions in sport and (2) undertake an expert Delphi consensus on the best practices for neck training implementation to reduce HAEs in sport. Part I: a systematic search of four databases was undertaken from the earliest records to September 2024. The PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analysis) guidelines were followed, and a quality assessment was completed using a modified Downs and Black assessment tool and the GRADE (Grading of Recommendations Assessment, Development and Evaluation). Papers were eligible if they both (1) implemented a reproducible exercise intervention targeting the neck within collision, combat or motor sport, and (2) assessed outcomes relating to either: the physical profile of the neck; head/neck injury incidence; and/or HAEs. Part II: 18 international experts, with experience in research and/or applied practice of neck exercise training, concussion and/or HAEs, reviewed the part I findings before completing a three-round Delphi consensus process. Part I included 21 papers, highlighting the heterogeneity of existing interventions. Part II resulted in 57 statements coded into five categories: contextual factors (n=17), neck training periodisation (n=12), training adaptations (n=10), neck training content (n=15) and athlete adherence (n=3). This study presents recommendations for neck exercise training aiming to reduce HAEs in sport, supporting both practice and future research.

Evaluating the Probability of Head Acceleration Events in Elite Men's and Women's Rugby Union Match-Play: The Impact of Tackle Height and Body Position

BACKGROUND

Head acceleration events (HAEs) are an increasing concern in collision sports owing to potential negative health outcomes.

OBJECTIVES

The objective of this study is to describe the probabilities of HAEs in tackles of differing heights and body positions in elite men's and women's rugby union.

METHODS

Instrumented mouthguards (iMGs) were worn in men's (n = 24 teams, 508 players, 782 observations) and women's (n = 26 teams, 350 players, 1080 observations) rugby union matches. Tackle height (i.e. point of contact on ball-carrier) and body positions of tacklers and ball-carriers were labelled for all tackles in which a player wore an iMG. HAEs from the initial impact were identified. Mean player, tackler and ball-carrier exceedance probabilities for various peak linear and angular acceleration thresholds were estimated from ordinal mixed-effects models.

RESULTS

Contact with ball-carriers' head/neck resulted in the highest mean HAE probabilities for both sexes. The probability of an HAE to the ball-carrier decreased as tackle height lowered. The highest probability for the tackler was initial contact to the ball-carriers upper leg. Body position influenced the probability of HAEs, with falling/diving ball-carriers resulting in higher mean probabilities. When a player, regardless of role, was bent-at-waist, elevated HAE probabilities were observed in men's competitions. Women's data demonstrated similar probabilities of an HAE for all body positions.

CONCLUSIONS

Initial contact to the ball-carrier's head/neck had the highest chance of an HAE, whilst role-specific differences are apparent for different tackle heights and body positions. Future player-welfare strategies targeting contact events should therefore consider HAE mechanisms along with current literature.

Neck strength deficit is a risk factor for concussion in high school rugby union and rugby league players

OBJECTIVES

Primary prevention of concussions is a priority in contact sports, with growing interest in the role of neck strength in mitigating the risks of concussion. The aim of this study was to determine if neck function was associated with in-season concussions in adolescent rugby union and league athletes, and to establish clinical values to identify players with increased risk of sustaining a concussion.

DESIGN

Prospective cohort study.

METHODS

Assessment of neck function included isometric strength, endurance and proprioception. In-season concussion injuries were recorded. Preliminary multivariate analysis-of-covariance models were conducted to investigate differences in neck function between players who did and did not sustain an in-season concussion. If significant, receiver operated characteristic curves were used to determine optimal cut-points for each variable to distinguish between concussion groups. Unadjusted odds ratios were estimated from the cross tabulation chi-squared test. Significance was set at p < 0.1.

RESULTS

A total of 43 players (aged 15-18 years) were assessed during preseason. Eleven players sustained a concussion during the season. Players who sustained a concussion during the season had weaker neck extension strength in kilogrammes (p = 0.043, effect size = 0.74) and when normalised to body weight (p = 0.041, effect size = 0.74). The optimal cut-point for extension strength was 32.1 kg (sensitivity 0.64, specificity 0.75) and 3.71 N/kg (sensitivity 0.64, specificity 0.66). Players with a flexor to extensor strength ratio above 0.74 were 3-times more likely to sustain a concussion (p = 0.09). There were no differences for other neck function variables.

CONCLUSIONS

Interventions targeting neck strength could reduce the risk of concussion.

The Incidence of Sports-Related Concussion in Children and Adolescents: A Systematic Review and Meta-Analysis

BACKGROUND

Sport-related concussions (SRC) are a concern for young athletes due to the potential for long-term health problems. This systematic review and meta-analysis aimed to provide a comprehensive overview of the literature exploring SRC incidence in youth sports to understand the associated risks.

METHODS

Medline, Embase, SPORTDiscus, PsycINFO, and Web of Science databases were searched without language restrictions up to September 2024. Studies were included if they (i) reported data for calculation of SRC incidence, (ii) were a prospective cohort study, and (iii) included a sample aged ≤ 18 years. Studies that reported Athlete Exposure (AE) or Player Hours (PH) as SRC incidence data measures were included in a multi-level random-effects meta-analysis. Additional analysis explored SRC incidence based on age, sex, country, year of data collection, setting, and level of contact.

RESULTS

Of the 6474 studies reviewed for eligibility, 116 studies were accepted for a systematic review and 99 in the meta-analysis. A total of 3,025,911 participants were included in the review (59% male, 41% female); however, 41% of studies did not report sample size. The pooled incidence rate of SRC per 1000 AE was found to be 1.41 across 21 sports, and 4.36 per 1000 PH across 7 sports. The highest incidence per 1000 AE were in taekwondo, rugby union, and ice hockey, and the highest incidence per 1000 PH were in rugby 7s, rugby league, and rugby union.

CONCLUSIONS

This systematic review and meta-analysis can serve as an updated baseline for risk of concussion among youth athletes across various sports.

TRIAL REGISTRATION

This systematic review was registered on OSF Registries ( https://osf.io/v298s ).

Reliability of a novel neck external loading dynamometer

Cervistab is an electro-pneumatic device that produces flexion push-loading events in an ecological rugby position (i.e. similar to on-pitch position) to assess neck extensors muscle response to a flexion perturbation. This response is important for preventing head/neck injuries in Rugby, however there is a clear lack of validated devices in the literature. This study tested the reliability of this new device designed to investigate the extensor neck muscle response to flexion head push-loading event. Twelve healthy volunteers were tested with Cervistab in a test/retest protocol. Participants experienced push-loading events with preloading on extensors muscles at 50 % and 20 % of their maximum voluntary isometric extension strength. Muscle mechanical latency, non-reflex and reflex rates of force development were measured twice, 7 days apart. Reliability was assessed by intraclass correlation coefficient (ICC), coefficient of variation (CV), and the Bland and Altman graphical approach. For both preloading conditions, muscle mechanical latency showed good ICC values from 0.81 to 0.88 and good CV (3.5%). Non-reflex and reflex rates of force development showed good reliability with ICC ranging from 0.78 to 0.89, and moderate CV values ranging from 8.5% to 14.5%, depending on the preloading condition (20% and 50% of maximal isometric extension contraction respectively). Bland and Altman plots showed no significant fixed or proportional bias. Overall, the reliability of measurements obtained with Cervistab is good. Cervistab can be used in practice to improve our understanding of the neuromechanical factors that influence neck stability, to help prevent head/neck injuries and to guide the decision to return to play after a head or neck injury.

Decreased isometric neck strength is a risk factor for head, neck and face injuries in professional rugby league players

Head, neck and face injuries are a concern in contact sports. This exploratory study aimed to establish 1) injury risk factors for head, neck and face injuries and 2) clinical cut-off values related to strength, endurance and proprioception of the cervical spine in a team of professional rugby league players. Pre-season assessments of isometric strength of the flexor, extensor and lateral flexor muscles, endurance of the flexor muscles and joint position error were conducted. Injuries resulting in games missed were recorded. Cross-tabulations were used to determine the unadjusted odds ratios for the measures as risk factors for playing season injuries. The unadjusted odds ratio (OR) values indicated that if a player had weaker extensors of the neck (<36.4 kg, p = 0.014; <3.4N/kg, p = 0.014) or asymmetry of isometric strength of their lateral flexor muscles (left-to-right ratio <0.91, p = 0.005), their odds of games missed due to season head, neck and face injuries was increased (OR extensors = 8; 95% CI = 1.5-42.5 OR asymmetry of lateral flexor muscles OR = 12.6; 95% CI = 2.0-79.4). As muscle strength is modifiable, the clinical application of this study would involve targeting players in the team beneath the clinical cut-off value.

'Downhill race for a rainbow jersey': the epidemiology of injuries in downhill mountain biking at the 2023 UCI cycling world championships-a prospective cohort study of 230 elite cyclists

Objectives

This study aims to understand the prevalence, incidence rate, anatomical sites, injury severity and main medical actions carried out during official training and racing by elite downhill mountain biking (DHMTB) riders during the 2023 Union Cycliste Internationale (UCI) Cycling World Championships.

Methods

The participants of this prospective, observational study were elite male and female cyclists competing at the UCI DHMTB World Championships located in the Nevis range in Fort William, Scotland, in 2023. This study followed the injury reporting guidelines established by the International Olympic Committee, which include the Strengthening the Reporting of Observational Studies in Epidemiology-Sports Injury and Illness Surveillance (SIIS) and the cycling-specific extension. Injuries were defined as 'tissue damage or other derangement of normal physical function due to participation in sports, resulting from rapid or repetitive transfer of kinetic energy requiring medical attention'. All epidemiological data were collected by the local organising committee medical professionals working at the event through an online survey. All data inputted were screened daily by the lead event physician and UCI medical delegate.

Results

Throughout 5 days of the championships, 10.4% of the 230 cyclists sustained at least one injury. The overall injury incidence rate was 3.3 (95% CI 3.1 to 3.5) per 100 rides. The incidence rates were higher in the training 4.3 (95% CI 4.0 to 4.6)/100 rides than in the racing 2.2 (95% CI 2.1 to 2.3)/100 rides. There was a greater incidence of injury in female cyclists in the training 5.8 (95% CI 5.0 to 6.6)/100 rides and racing 4.5 (95% CI 3.9 to 4.9)/100 rides compared with male cyclists. Female cyclists experienced more severe injuries, with an average of 12.6 (±14, 95% CI 5.66 to 19.54) days lost to injury compared with 5.5 (±1.6 95% CI 1.89 to 9.11) seen in male cyclists. The main event medical actions were lifting, immobilisation and helmet removal.

Conclusion

This study provides insights into the risk of injury to athletes within DHMTB. Our findings suggest more focus should be placed on the female DHMTB athlete. Additionally, this study provides unique information about common medical actions required of medical professionals working at DHMTB events and the importance of pre-event scenario training.

Reliability of a Musculoskeletal Assessment for the Examination of Cervical Spine Pain and Injuries in Special Forces Combat Soldiers

An assessment of protocol reliability is an essential step prior to human subject testing for injury prevention. The purpose of this study was to examine the inter-rater and intra-rater reliability of a portable cervical range of motion and isometric strength protocol designed for special forces combat soldiers who are at risk for cervical spine pain and injury due to exposure to head-supported mass. Eight individuals were tested three times to assess reliability, the standard error of the measurement (SEM), and the minimal detectable change across six range of motion measures and six strength measures of the cervical spine. One tester tested all participants twice for intra-rater reliability, and a second tester assessed the participants to examine inter-tester reliability. All reliability measures demonstrated good to excellent reliability (ICC = 0.70-0.96 (isometric strength); ICC = 0.85-0.94 (range of motion)). All SEM scores were 12% or lower for all reliability measures. The findings of this study demonstrate that the protocol developed for a longitudinal multi-site study is reliable and appropriate to implement for injury prevention in military personnel.

Acute effects of an isometric neck warm-up programme on neck performance characteristics and ultrasound-based morphology

OBJECTIVE

Athletic performance can be enhanced immediately after an isometric warm-up, a phenomenon termed post-activation performance enhancement (PAPE). While isometric warm-ups can improve lower extremity sprint and jump performance, neck-specific isometric warm-ups need development and validation for mild traumatic brain disorders and neck pain. This study examined acute effects of isometric warm-ups on neck performance and morphology.

METHODS

Arm 1: Twenty-six adults (13 M:13F) completed neck performance testing before and after a 10-minute neck isometric warm-up or stationary bike (sham) between two visits. Testing included visual-motor reaction time, peak force, rate of force development, force steadiness, and force replication/proprioception measured by a 6-axis load cell. An inclinometer assessed range-of-motion. Paired t-tests and two-way ANOVA examined effects of neck/bike warm-up and interaction effects, respectively. Arm 2: 24 adults (11 M:13F) completed ultrasound scans of cervical muscles: before 20-minute rest (sham), and before/after a 5-min neck isometric warm-up. Longus colli cross-sectional area and sternocleidomastoid/upper trapezius thickness and stiffness, and cervical extensors thickness was assessed. One-way ANOVA compared morphological values at sham, before, and after warm-up. Significance was set at p < 0.05.

RESULTS

Isometric neck warm-up increased rate of force development in flexion (p = 0.022), extension (p = 0.001-0.003), right lateral flexion (p = 0.004-0.032), left lateral flexion (p = 0.005-0.014), while peak force improved only in left lateral flexion (p = 0.032). Lateral flexion range-of-motion increased after neck warm-up (p = 0.003-0.026). Similarly, longus colli cross-sectional area (p = 0.016) and sternocleidomastoid thickness (p = 0.004) increased.

CONCLUSIONS

Increased neck performance characteristics and morphology are likely due to PAPE effects of isometric neck warm-up. For coaches and athletes, simple isometric contractions could be added to existing warm-ups to reduce prevalence, incidence, and severity of mild traumatic brain injuries and neck pain.

Reply to "Asking the Right Question Is Key to Getting a Valuable Answer"

Author response to the JOSPT Letter to the Editor-in-Chief "Asking the Right Question is Key to Getting a Valuable Answer" J Orthop Sports Phys Ther 2023;53(11):726-727. doi:10.2519/jospt.2023.0204-R.

Concussion Rehabilitation and the Application of Ten Movement Training Principles

Concussion awareness continues to grow in all aspects of healthcare, including the areas of prevention, acute care, and ongoing rehabilitation. Most of the concussion research to date has focussed on the challenges around screening and diagnosing what can be a complex mix of brain impairments that overlay with additional pre-existing comorbidities. While we expect further progress in concussion diagnosis, progress also continues to be made around proactive rehabilitation, with the emergence of interventions that can enhance the recovery process, maximise function and independence with a return to study, work, and play. Traditionally, optimal multimodal assessments of concussion have treated the physical, cognitive, and psychological domains of brain injury separately, which supports diagnosis, and informs appropriate follow-up care. Due to the complex nature of brain injury, multimodal assessments direct care toward professionals from many different disciplines including medicine, physiotherapy, psychology, neuropsychology, ophthalmology, and exercise physiology. In addition, these professionals may work in different fields such as sports, neurorehabilitation, vestibular, musculoskeletal, community, vocational, and general practice clinical settings. Rehabilitation interventions for concussions employed in practice are also likely to use a blend of theoretical principles from motor control, cognitive, and psychological sciences. This scale of diversity can make information dissemination, collaboration, and innovation challenging. The Ten Movement Training Principles (MTPs) have been proposed as a usable and relevant concept to guide and support clinical reasoning in neurorehabilitation. When applied to concussion rehabilitation, these same 10 principles provide a comprehensive overview of key rehabilitation strategies for current and future practice. Future collaborations can use these training principles to support clinical and research innovations including the rapid rise of technologies in this growing field of rehabilitation practice.