Jason’s Articles of the Month (March 2021)

Another monthly addition of my articles of the month! These articles cover sports-related concussion, repetitive head impacts, ACL injury risk, and the relationship between cognition and neuromotor performance.

Summary: Large prospective study of nearly 5,000 athletes that determined musculoskeletal injury rate was 87% greater in athletes who reported a prior sports-related concussion (SRC) within the previous 12 months. Interesting, this relationship was only present in non-contact, acute musculoskeletal injuries after SRC.

Summary: Individuals with a history of ACLR and matched controls completed neurocognitive testing, a lower extremity proprioception assessment, measures of dynamic lower extremity control, and neuroimaging. Increased visual cognition was associated with better proprioception and decreased time to stability during the jump-landing. Visual cognition was also associated with increased activation in brain regions related to sensory processing and motor control.

Summary: Knee biomechanics have been heavily studied as it relates to noncontact knee injuries in athletes. In this review, knee kinematics and kinetics were not associated with injury. This may be due to biomechanical assessments often ignoring any sort of cognitive constraint (e.g, temporal, space, obstacles) that is commonly seen in a sporting environment.

Summary: This was the first investigation to examine the relationship between repetitive head impacts and cervical spinal cord white matter integrity. White matter tracts associated with balance and postural control were most negatively affected following one season of football. Subsequent studies following concussive events may provide greater insight into the neural underpinnings of greater risk for lower extremity injury post-SRC.

Summary: A seminal paper defining various constructs of sports injury occurrence, data analysis, and injury risk factors and prevention. Recommended reading for anyone involved in sports injury research and clinical practice.

Jason’s Articles of the Month (February 2021)

At the beginning of each month, I am going to start posting 5-10 articles I’ve reviewed and believe to be important for clinicians, coaches, parents, etc.

I’ll likely focus these articles on sports-related concussion, ACL injury, adolescent athletes, and biomechanics. Enjoy!

Summary: While there have been previous lower extremity injury surveillance datasets conducted in a variety of athletes post-concussion, this article was the first to demonstrate a specific relationship between concussion and ACL injury. Those with a concussion history in the previous 3 years were 1.6x more likely to sustain and ACL injury compared to controls. About half of the total cases examined in this study were due to sport.

Summary: Injury prediction is the holy grail of sports science. This article provides a nice overview of why current injury prediction methods are flawed (namely due to cross-sectional nature of screening) and provides opportunities to improve our models.

Summary: This article reviews biomechanical and physiological adaptations that occur after ACL injury and offers integrated strategies to restore motor control post-ACLR. Commentary is provided through perspectives including neuroscience, biomechanics, motor control/learning, and psychology.

Summary: One of the first articles to demonstrate the influence of neurocognition on musculoskeletal injury. Collegiate athletes who sustained a noncontact ACL injury performed worse on assessments of reaction time, working memory, and processing speed compared to matched controls.

Summary: This paper offers possible neuromuscular explanations for increased risk of musculoskeletal injury after concussion. Neuromuscular control post-concussion may be better understood by utilizing dynamic tasks during clinical rehabilitation, including gait and/or sport-specific scenarios.

Sports-Related Concussion in the Adolescent Athlete

In this blog post, I’m going to discuss sports-related concussion in adolescent athletes.  I’ll also discuss the research I conducted at UNLV, in which I examined lower body injury risk in previously concussed youth athletes.

Sports-related concussions (SRCs) are a major epidemiological concern among the adolescent athletic population.  The majority of SRCs in the United States are sustained by adolescents athletes (< 18 years old), as it is estimated that 1.1–1.9 million cases occur annually.3  Similarly to collegiate and professional counterparts, sports such as football, lacrosse, ice hockey, and soccer account for the highest rates of SRCs in youth athletics.1,11,16  Additionally, it appears that the risk of SRC in youths is increasing at comparable rates to older sport competitors.  Over an 11 year study period consisting of 158,430 high school athletes, Lincoln et al. (2011) reported a 15.5% increase in reported SRCs, a trend similar to collegiate male football participants.19

It has been suggested that adolescent athletes require a more conservative approach to SRC management and return-to-sport.6  The majority of collegiate and professional competitors receive clinical clearance to resume sport participation 5–7 days post-SRC,13,14  however, it appears that youth athletes take longer for symptoms to resolve,7,17 as well as a return to pre-concussive performance on NP tests5 and postural control tasks9,15 compared to older individuals.  While reported SRC symptoms (headache, dizziness, and difficulty concentrating) were similar across age groups, 19.5% and 16.3% of high school and adolescent football athletes required at least 30 days to resume sport, respectively, compared with 7% of collegiate competitors.10

It appears that task difficulty may influence SRC recovery trajectories in the adolescent athlete.  While the majority of adolescent athletes return-to-sport within four weeks post-SRC,7 locomotor deficits may still be present when paired with a secondary cognitive task.  In a study comparing adolescent (mean age = 15 years old) and young adult (mean age = 20 years old) recovery trajectories following a concussive injury, Howell et al. (2014) found that adolescents were less accurate on a Stroop task and displayed greater ML COM displacement during a dual-task walking condition compared to adolescent controls at two months post-SRC.9  These cognitive and motor deficits were not determined in the concussed young adult group when matched to their control group.9  Interestingly, Howell et al. (2018) revealed that post-concussive adolescent athletes who reported a future sports-related injury (SRC or musculoskeletal) demonstrated an approximately 8% increase in dual-task cost walking speed over a one year time period.8  This recent finding suggests that while clinical clearance may be granted within a four week time period for the majority of adolescents, subtle locomotor deficits may linger beyond sport resumption and contribute to future injury risk.  Presently, researchers have not be able to adequately predict indicators of prolonged recovery,20 potentially attributed to large inter-individual variances in cognitive growth and maturation among adolescents.  It has been suggested that prolonged SRC recovery in the adolescent athlete may be due to various factors including continued cognitive development,10 inadequate neck strength,4 and the time to which one seeks medical care from a concussion specialist.2  In their examination of factors related to delayed recovery from SRC, Bock et al. (2015) reported that 62.3% of concussed adolescents did not seek medical care until at least one week post-injury.2  Those who were evaluated by a concussion specialist within a week of injury reported significantly shorter RTP time (median = 16 days) versus those who waited beyond one week (median = 36 days).2

Recent research suggests that concussed adolescent athletes are at a greater risk for lower body injury.  In a study of 18,216 male and female high school athletes, investigators determined that lower body injury risk resulting in time-loss from sport (defined as greater than the day of injury) increased by 34% for every previous SRC.12  However, a prior SRC did not result in greater risk of a non-time loss injury, although the distinction between the lower body injury classification following an SRC in high school athletes is presently unclear.12  The mechanisms responsible for an elevated lower body injury risk post-SRC in the adolescent athlete are presently unclear, however, Reed, Taha, Monette, and Keightley (2016) found that concussed teenage hockey players performed significantly worse on isometric handgrip and squat jump tests during the symptomatic and asymptomatic time periods compared to controls.18

While neuromuscular alterations may exist beyond clinical clearance to resume sport, my doctoral research at UNLV sought to examine biomechanical patterns during drop-landing tasks in adolescent athletes with and without an SRC history.  The video below is a from the UNLV 3-Minute Thesis competition (I placed second overall) and the link is from a recent interview with the UNLV Graduate College.

3MT – https://www.youtube.com/watch?v=d0gnBNnhV3E

Interview – https://www.unlv.edu/news/article/concussions-ripples-felt-throughout-body

Essentially, I found biomechanical alterations at both the ankle and knee joints that would suggest post-concussive adolescents are at greater risk for lower body injury during landing tasks.  We’re in the peer-review process for this particular study, so be on the lookout for that (hopefully) soon.  I’m still attempting to determine the why post-concussive athletes are at greater risk for lower body injury well beyond symptom resolution and a (seemingly) return to baseline cognitive performance; my next research studies will be examining neuropsychological correlates to lower body injury risk in collegiate athletes who have a prior SRC history.  Hopefully this will give us a better understanding of the association between SRC and lower body injury.  Stay tuned…


Twitter – @JasonAvedesian

Email – jason.avedesian@unlv.edu


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