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.

Rethinking ACL Rehabilitation and Prevention

Hi all! Below is a preliminary list of ACL literature connecting motor learning to prevention and rehabilitation. By no means is this an exhaustive live. It’ll be updated. PDF’s are available! Just email one of us.

ACL injury prevention, more effective with a different way of motor learning?

https://link.springer.com/article/10.1007/s00167-010-1313-z

Optimization of the anterior cruciate ligament injury prevention paradigm: novel feedback techniques to enhance motor learning and reduce injury risk.

https://www.jospt.org/doi/pdfplus/10.2519/jospt.2015.4986

Principles of Motor Learning to Support Neuroplasticity After ACL Injury: Implications for Optimizing Performance and Reducing Risk of Second ACL Injury

https://link.springer.com/article/10.1007/s40279-019-01058-0

Novel methods of instruction in ACL injury prevention programs, a systematic review

Click to access Novel-methods-of-instruction-in-ACL-injury-prevention-programs-a-systematic-review.pdf

Mechanisms Underlying ACL Injury-Prevention
Training: The Brain-Behavior Relationship

https://www.natajournals.org/doi/pdf/10.4085/1062-6050-45.5.513

The effects of attentional focus on jump performance and knee joint kinematics in patients after ACL reconstruction

Click to access GokelerPhysTherSport2015.pdf

Immersive virtual reality improves movement patterns in patients after ACL reconstruction: implications for enhanced criteria- based return-to-sport rehabilitation

Click to access 544a22e90cf2f6388084f5a5.pdf

Using principles of motor learning to enhance ACL injury prevention programs

https://scholar.google.co.uk/scholar?hl=en&as_sdt=0%2C5&q=ACL+motor+learning&oq=#d=gs_qabs&u=%23p%3Dg2wsIea72HEJ

Training for Prevention of ACL Injury: Incorporation of Progressive Landing Skill Challenges Into a Program

Click to access Training_for_Prevention_of_ACL_Injury__.10.pdf

Feedback Techniques to Target Functional Deficits Following Anterior Cruciate Ligament Reconstruction: Implications for Motor Control and Reduction of Second Injury Risk

https://link.springer.com/article/10.1007/s40279-013-0095-0

CONSIDERATIONS FOR LATE STAGE ACL REHABILITATION AND RETURN TO SPORT TO LIMIT RE‐INJURY RISK AND MAXIMIZE ATHLETIC PERFORMANCE

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4387733/

Neuroplasticity Following Anterior Cruciate Ligament Injury: A Framework for Visual-Motor Training Approaches in Rehabilitation

https://www.jospt.org/doi/full/10.2519/jospt.2015.5549

Review of the Afferent Neural System of the Knee and Its Contribution to Motor Learning

https://www.jospt.org/doi/pdfplus/10.2519/jospt.1994.19.1.2

Altered electrocortical brain activity after ACL reconstruction during force control

https://onlinelibrary.wiley.com/doi/full/10.1002/jor.21380

Neuroplasticity Associated With Anterior Cruciate Ligament Reconstruction

https://www.ncbi.nlm.nih.gov/pubmed/27817301

Does brain functional connectivity contribute to musculoskeletal injury? A preliminary prospective analysis of a neural biomarker of ACL injury risk

Click to access diekfuss_brain_connectivity_injuries.pdf

A novel approach to enhance ACL injury prevention programs

https://link.springer.com/article/10.1186/s40634-018-0137-5

Is neuroplasticity in the central nervous system the missing link to our understanding of chronic musculoskeletal disorders?

https://link.springer.com/article/10.1186/s12891-015-0480-y

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…

Jason

Twitter – @JasonAvedesian

Email – jason.avedesian@unlv.edu

References

  1. Bakhos LL, Lockhart GR, Myers R, Linakis JG. Emergency Department Visits for Concussion in Young Child Athletes. PEDIATRICS. 2010;126(3):e550-e556. doi:10.1542/peds.2009-3101.
  2. Bock S, Grim R, Barron TF, et al. Factors associated with delayed recovery in athletes with concussion treated at a pediatric neurology concussion clinic. Child’s Nervous System. 2015;31(11):2111-2116. doi:10.1007/s00381-015-2846-8.
  3. Bryan MA, Rowhani-Rahbar A, Comstock RD, Rivara F, Seattle Sports Concussion Research Collaborative. Sports- and Recreation-Related Concussions in US Youth. PEDIATRICS. 2016;138(1):e20154635-e20154635. doi:10.1542/peds.2015-4635.
  4. Collins MW, Kontos AP, Reynolds E, Murawski CD, Fu FH. A comprehensive, targeted approach to the clinical care of athletes following sport-related concussion. Knee Surg Sports Traumatol Arthrosc. 2014;22(2):235-246. doi:10.1007/s00167-013-2791-6.
  5. Covassin T, Elbin RJ, Harris W, Parker T, Kontos A. The Role of Age and Sex in Symptoms, Neurocognitive Performance, and Postural Stability in Athletes After Concussion. Am J Sports Med. 2012;40(6):1303-1312. doi:10.1177/0363546512444554.
  6. Foley C, Gregory A, Solomon G. Young age as a modifying factor in sports concussion management: what is the evidence? Curr Sports Med Rep. 2014;13(6):390-394. doi:10.1249/JSR.0000000000000104.
  7. Halstead ME, Walter KD, Moffatt K, Council on Sports Medicine and Fitness. Sport-Related Concussion in Children and Adolescents. Pediatrics. 2018;142(6). doi:10.1542/peds.2018-3074.
  8. Howell DR, Buckley TA, Lynall RC, Meehan WP. Worsening Dual-Task Gait Costs after Concussion and their Association with Subsequent Sport-Related Injury. Journal of Neurotrauma. 2018;35(14):1630-1636. doi:10.1089/neu.2017.5570.
  9. Howell DR, Osternig LR, Koester MC, Chou L-S. The effect of cognitive task complexity on gait stability in adolescents following concussion. Exp Brain Res. 2014;232(6):1773-1782. doi:10.1007/s00221-014-3869-1.
  10. Kerr ZY, Zuckerman SL, Wasserman EB, Covassin T, Djoko A, Dompier TP. Concussion Symptoms and Return to Play Time in Youth, High School, and College American Football Athletes. JAMA Pediatrics. 2016;170(7):647. doi:10.1001/jamapediatrics.2016.0073.
  11. Lincoln AE, Caswell S V., Almquist JL, Dunn RE, Norris JB, Hinton RY. Trends in Concussion Incidence in High School Sports. The American Journal of Sports Medicine. 2011;39(5):958-963. doi:10.1177/0363546510392326.
  12. Lynall RC, Mauntel TC, Pohlig RT, et al. Lower Extremity Musculoskeletal Injury Risk After Concussion Recovery in High School Athletes. Journal of Athletic Training. 2017;52(11):1062-6050-52.11.22. doi:10.4085/1062-6050-52.11.22.
  13. Makdissi M, McCrory P, Ugoni A, Darby D, Brukner P. A Prospective Study of Postconcussive Outcomes after Return to Play in Australian Football. The American Journal of Sports Medicine. 2009;37(5):877-883. doi:10.1177/0363546508328118.
  14. McCrea M, Guskiewicz KM, Marshall SW, et al. Acute Effects and Recovery Time Following Concussion in Collegiate Football Players. The Journal of the American Medical Association. 2003;290(19):2556-2563. doi:10.1001/jama.290.19.2556.
  15. Nelson LD, Guskiewicz KM, Barr WB, et al. Age Differences in Recovery After Sport-Related Concussion: A Comparison of High School and Collegiate Athletes. Journal of athletic training. 2016;51(2):142-152. doi:10.4085/1062-6050-51.4.04.
  16. O’Connor KL, Baker MM, Dalton SL, Dompier TP, Broglio SP, Kerr ZY. Epidemiology of Sport-Related Concussions in High School Athletes: National Athletic Treatment, Injury and Outcomes Network (NATION), 2011–2012 Through 2013–2014. Journal of Athletic Training. 2017;52(3):175-185. doi:10.4085/1062-6050-52.1.15.
  17. Purcell L, Harvey J, Seabrook JA. Patterns of Recovery Following Sport-Related Concussion in Children and Adolescents. Clinical pediatrics. 2016;55(5):452-458. doi:10.1177/0009922815589915.
  18. Reed N, Taha T, Monette G, Keightley M. A Preliminary Exploration of Concussion and Strength Performance in Youth Ice Hockey Players. International Journal of Sports Medicine. 2016;37(09):708-713. doi:10.1055/s-0042-104199.
  19. Westermann RW, Kerr ZY, Wehr P, Amendola A. Increasing Lower Extremity Injury Rates Across the 2009-2010 to 2014-2015 Seasons of National Collegiate Athletic Association Football. The American Journal of Sports Medicine. 2016;44(12):3230-3236. doi:10.1177/0363546516659290.
  20. Zemek RL, Farion KJ, Sampson M, McGahern C. Prognosticators of persistent symptoms following pediatric concussion: A systematic review. JAMA Pediatrics. 2013;167(3):259-265. doi:10.1001/2013.jamapediatrics.216.

The Rebel Movement Podcast (Episode 2) – ACL and the Brain: From Research to Application

We had a great time chatting away last night on ACL injury, prevention, rehabilitation and more! We had a privilege to talk through the lens of our own disciplines (biomechanics and motor learning). Let us know what you like, dislike, and how we can improve. As always, if you’d like to write for our blog, please reach out to either one of us!

Article Links:

Strategies to Reduce ACL Injury Risk in Youth Athletes – Part 1 (The Warm-Up)

While there are numerous benefits to youth sport participation, it is imperative that clinicians and practitioners address the risk of injury that may occur. I want to make it clear that my intention for this post is not to deter individuals from participation in the well-documented positive outcomes of youth sport, but to make those involved aware of a few mechanisms surrounding potential injury. Mechanisms that when addressed early and in the correct fashion, can lead to a lifetime of many positive health outcomes.

My goal is to create an interactive database applicable to practitioners, coaches, and parents. Ultimately, they are the ones with the opportunity to implement these strategies with their athletes. Through a variety of media modalities, I plan to release a new angle on strategies for anterior cruciate ligament (ACL) injury risk reduction each month or so. I have an outline of how I would like to release this information, but would love to continue to build on these posts based on feedback. As always, please reach out if there is something you would like to discuss or you think would be pertinent information for this project. Input and collaboration, big or small, will ultimately allow us to solve some of the issues surrounding ACL injury in youth sports.

Across multiple posts throughout the summer, I am going to discuss and explore a variety of strategies that may be useful in keeping your youth athletes on the field. My past and present research focuses on ACL injury mechanisms in various sporting populations, so I’ll focus the majority of my attention on strategies to reduce this risk. ACL injury has become a major concern within youth athletics that may significantly alter ones sporting career and overall well-being. In my experience, many coaches and parents are initially unaware of strategies to mitigate ACL injury risk in their children. There tends to be a reliance on ‘over-competing’ and ‘under-training’, with little thought given to feasible warm-up, strength training, nutritional, psychological, and sleep strategies to reduce ACL injury risk. What is particularly troubling is that the rate of ACL injury in adolescent athletes (ages 6-18) has risen by 2.3% over a 20 year period (Beck, 2016). This may be attributed to a combination of many factors including (but not limited to): early sport specialization (Bell, 2018), insufficient recovery from sport/life stressors, and inadequate/non-compliant fitness preparation and training (Soligard, 2010).

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Before diving into ways to reduce injury risk, let’s start with the ACL itself. A major structure of the knee joint, the ACL plays a crucial role in stabilizing the knee during motion and allowing the lower leg to move through its normal range-of-motion. With one of the largest mechanoreceptor concentrations in the lower extremity, the ACL provides vital proprioceptive information to the central nervous system when the knee is in motion (Decker, 2011). An ACL injury can be classified as a contact or non-contact injury, and an estimated 70% of sport-related injuries take place in non-contact situations (Griffin, 2000). A non-contact ACL injury often occurs when an athlete performs a sudden landing, deceleration, or cutting maneuver (Griffin, 2000). During these maneuvers, athletes may injure the ACL when the knee is near full extension, ranging from 10-30 degrees of knee flexion (Boden, 2000). Further observation of knee motion during sporting movements has led researchers to believe excessive frontal plane motion may also contribute to ACL injury (Grandstrand, 2006), however, it is likely that an injury to the ACL is multiplanar in nature (Shimokochi, 2008). This includes excessive anterior tibia motion (Shimokochi, 2008), high knee rotational torque (Quatman, 2009), and valgus collapse (Quatman, 2009) that potentially lead to an ACL sprain or tear. Along with biomechanical factors, neuromuscular movement patterns such as increased activation of the quadriceps musculature places significant strain on the ACL at low knee flexion angles (Markolf, 2004). The ACL is at an increased risk of injury when excessive quadriceps forces are combined with excessive multiplanar knee motions (Shimokochi, 2008).

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In Part 1 of this series, I figure we begin with the most intuitive prevention strategy, one that I spent two years studying during my master’s degree, and one that often gets inadequate focus: the warm-up.

Warm-Ups

During competition, an athlete may be subjected to repetitive high force patterns and unpredictable movements, potentially leading to increased ACL injury risk, and evidence indicates the majority of ACL injuries take place in game situations (Bradley, 2002) under noncontact conditions. The timing of ACL injuries has not been extensively examined, but some researchers propose that an athlete may be at an increased risk of injury under a fatigued state (Borotikar, 2008). However, a review of fatiguing protocols on lower limb biomechanics revealed varying effects of fatigue on knee mechanics during athletic tasks (Barber-Westin, 2017), suggesting fatigue may not heighten ACL injury risk. While the effects of fatigue on ACL injury is inconsistent, more recent evidence indicates that athletes are injuring the ACL earlier in competition. A study from the NBA reported that the first quarter accounted for the second highest ACL injury incidence (24%), compared to 13%, 22%, and 40% in the second, third, and fourth quarter, respectively (Harris, 2013). A video-based analysis of male soccer ACL injury mechanisms and situations revealed that 26% of injuries occurred within the first nine minutes of match play, leading investigators to speculate the effects of insufficient physical preparation prior to the match (Grassi, 2017). In a three-cohort study of professional soccer players, 57% of ACL injuries occurred in the first half of matches and approximately 22% in the first 15 minutes of match time (Waldén, 2011).  Furthermore, the majority of ACL injuries in female soccer athletes were sustained within the first 15 minutes of each half, leading the authors to speculate the effects of warm-up on ACL injury between sexes (Waldén, 2011).

In order to adequately prepare their bodies for activity, youth athletes should participate in warm ups prior to any training or competitive event. While there are many warm-up modalities, you may find yourself asking, what are best warm-up practices to reduce ACL injury risk? Research indicates that an adequate warm-up consists of the following: 1) whole-body and multidirectional dynamic movements, 2) movement progression from general to sport-specific and 3) completed within 15-20 minutes (Barengo, 2014). A study from Olsen (2005) determined that a warm-up consisting of the above-mentioned modalities reduced the risk of acute ankle and knee injuries by approximately 50% in adolescent athletes. Similarly, Mandelbaum (2005) revealed that ACL injury decreased by 74-88% in adolescent female soccer players following a warm-up of general exercise, plyometric activity, soccer-specific drills, and light stretching. A more recently developed and popular warm-up among soccer athletes is the FIFA 11+ program. The FIFA 11+ takes approximately 20 minutes to complete and requires minimal equipment, with the warm-up itself consisting of partner running, jump-landings, and core stabilization drills. A recent review concluded that the FIFA 11+ demonstrates a 30% reduction in the risk of injury in adolescent soccer athletes (Sadigursky, 2017).

I took the warm-up research a step further during my Master’s degree at Ball State University. My thesis examined the acute effects of two different warm-up strategies on single-leg landing mechanics in female volleyball athletes. The athletes came to the laboratory for two testing sessions, performing a 1) dynamic stretching warm-up and 2) dynamic + static stretching warm-up. Landing biomechanics were examined across three time points (pre warm-up, 1 minute post warm-up and 15 minutes post warm-up). I found that athletes demonstrated greater torque (abduction moment) on the non-dominant knee following a warm-up that included dynamic + static stretching. I postulated that increased muscular compliance and decreased force generating capabilities of the hamstrings and glutes after static stretching were potential mechanisms leading to higher risk landing patterns (Avedesian, 2019). In summary, athletes were better off performing a dynamic warm-up without static stretching when assessing landing biomechanics associated with ACL injury risk.

To give another example, let’s run through an example of what a strong, foundational warm-up would look like for an adolescent jump-landing athletes (i.e., basketball, volleyball, soccer).

  1. 50-yard jog around court
  2. Walking quadriceps stretch
  3. Frankensteins (right/left foot reaching up towards left/right hand)
  4. Single-leg hip hinge
  5. Shuffles with alternating groin stretch
  6. High-knee pull to lung with trunk rotation
  7. Ten yard sideways run
  8. Ten yard backwards run
  9. Butt kicks to high knee runs
  10. Skip-hops
  11. Partner bumps with single-leg landings
  12. Partner zig-zag runs
  13. Double/single-leg triple jumps (repeat 3X)
  14. Five yard shuffle to 10-yard sprint (repeat 2X each side)
  15. Two countermovement jumps to 10-yard sprint with active deceleration (repeat 3X)

(Note: instruct the athletes to jog back to the starting position upon completion of each exercise, all exercises can be completed within 10-15 yards).

The provided warm-up examples can be easily implemented into any practice regimen and can even create a teambuilding experience if run by the athletes themselves once proficiency is demonstrated. The coaches should be watching and providing feedback and instruction as necessary. But the sense of ownership and autonomy from athlete-led warm-ups may increase compliance in the long-term (Gillet, 2010). This is important because adherence to these protocols must be high in order to see the benefits in injury risk reduction. In examining compliance to an injury-specific warm-up, Soligard (2010) found that high compliance teams (competing warm-up in 70% of training/competition) demonstrated a 35% reduction in injury risk compared to teams with intermediate compliance (warm-up completion in 42% of training/competition).

So, to wrap everything up from this post.

1) ACL injury risk is high in adolescent athletes

2) The majority of ACL injuries occur under non-contact situations and often early in competition

3) Warm-ups with high adherence that include dynamic activity and sport-specific exercise may reduce the risk of ACL injury

Now that we have discussed warm-up implementation, let’s shift to considerations for strength training. Part 2 coming soon.

– Jason

Twitter: @JasonAvedesian

Email: jason.avedesian@unlv.edu

References

Avedesian, J. M., Judge, L. W., Wang, H., & Dickin, D. C. (2018). Kinetic Analysis of Unilateral Landings in Female Volleyball Players After a Dynamic and Combined Dynamic-Static Warm-up. Journal of Strength and Conditioning Research. doi:10.1519/jsc.0000000000002736

Barber-Westin, S. D. & Noyes, F. R. (2017). Effect of Fatigue Protocols on Lower Limb Neuromuscular Function and Implications for Anterior Cruciate Ligament Injury Prevention Training. Am. J. Sports Med. 363546517693846. doi:10.1177/0363546517693846

Bell, D. R., Post, E. G., Biese, K., Bay, C., & Mcleod, T. V. (2018). Sport Specialization and Risk of Overuse Injuries: A Systematic Review With Meta-analysis. Pediatrics,142(3). doi:10.1542/peds.2018-0657

Beck, N. A., Lawrence, J. T., Nordin, J. D., Defor, T. A., & Tompkins, M. (2016). ACL Tears in School-Aged Children and Adolescents: Has There Been an Increased Incidence over the Last 20 Years? Pediatrics,137(Supplement 3). doi:10.1542/peds.137.supplement_3.554a

Boden, B. P., Griffin, L. Y. & Garrett, W. E. (2000). Etiology and Prevention of Noncontact ACL Injury. Phys. Sportsmed. 28, 53–60.

Borotikar, B. S., Newcomer, R., Koppes, R. & McLean, S. G. (2008). Combined effects of fatigue and decision making on female lower limb landing postures: central and peripheral contributions to ACL injury risk. Clin. Biomech. 23, 81–92.

Bradley, J. P., Klimkiewicz, J. J., Rytel, M. J. & Powell, J. W. (2002). Anterior cruciate ligament injuries in the National Football League: epidemiology and current treatment trends among team physicians. Arthrosc. J. Arthrosc. Relat. Surg. Off. Publ. Arthrosc. Assoc. N. Am. Int. Arthrosc. Assoc. 18, 502–509.

Decker, L. M., Moraiti, C., Stergiou, N. & Georgoulis, A. D. (2011). New insights into anterior cruciate ligament deficiency and reconstruction through the assessment of knee kinematic variability in terms of nonlinear dynamics. Knee Surg. Sports Traumatol. Arthrosc. Off. J. ESSKA 19, 1620–1633.

Gillet, N., Vallerand, R. J., Amoura, S., & Baldes, B. (2010). Influence of coaches autonomy support on athletes motivation and sport performance: A test of the hierarchical model of intrinsic and extrinsic motivation. Psychology of Sport and Exercise,11(2), 155-161. doi:10.1016/j.psychsport.2009.10.004

Grandstrand, S. L., Pfeiffer, R. P., Sabick, M. B., DeBeliso, M. & Shea, K. G. (2006). The effects of a commercially available warm-up program on landing mechanics in female youth soccer players. J. Strength Cond. Res. 20, 331–335.

Grassi, A. et al. (2017). Mechanisms and situations of anterior cruciate ligament injuries in professional male soccer players: a YouTube-based video analysis. Eur. J. Orthop. Surg. Traumatol. Orthop. Traumatol. doi:10.1007/s00590-017-1905-0

Griffin, L. Y. et al. (2000). Noncontact anterior cruciate ligament injuries: risk factors and prevention strategies. J. Am. Acad. Orthop. Surg. 8, 141–150.

Harris, J. D. et al. (2013). Return-to-Sport and Performance After Anterior Cruciate Ligament Reconstruction in National Basketball Association Players. Sports Health 5, 562–568.

Hejna, W. F., Rosenberg, A., Buturusis, D. J., & Krieger, A. (1982). The Prevention of Sports Injuries in High School Students Through Strength Training. National Strength Coaches Association Journal,4(1), 28-31. doi:10.1519/0199-610x(1982)0042.3.co;2

Lauersen, J. B., Bertelsen, D. M., & Andersen, L. B. (2014). The effectiveness of exercise interventions to prevent sports injuries: A systematic review and meta-analysis of randomised controlled trials. British Journal of Sports Medicine,48(11), 871-877. doi:10.1136/bjsports-2013-092538

Mandelbaum, et al. (2005). Effectiveness of a Neuromuscular and Proprioceptive Training Program in Preventing Anterior Cruciate Ligament Injuries in Female Athletes. The American Journal of Sports Medicine,33(7), 1003-1010. doi:10.1177/0363546504272261

Markolf, K. L., O’Neill, G., Jackson, S. R. & McAllister, D. R. (2004). Effects of applied quadriceps and hamstrings muscle loads on forces in the anterior and posterior cruciate ligaments. Am. J. Sports Med. 32, 1144–1149.

Olsen, O., Myklebust, G., Engebretsen, L., Holme, I., & Bahr, R. (2005). Exercises to prevent lower limb injuries in youth sports: Cluster randomised controlled trial. BMJ,330(7489), 449. doi:10.1136/bmj.38330.632801.8f

Sadigursky, D., Braid, J. A., Lira, D. N., Machado, B. A., Carneiro, R. J., & Colavolpe, P. O. (2017). The FIFA 11 injury prevention program for soccer players: A systematic review. BMC Sports Science, Medicine and Rehabilitation,9(1). doi:10.1186/s13102-017-0083-z

Shimokochi, Y. & Shultz, S. J. (2008). Mechanisms of Noncontact Anterior Cruciate Ligament Injury. J. Athl. Train. 43, 396–408.

Soligard, T. et al. (2010). Compliance with a comprehensive warm-up programme to prevent injuries in youth football. British Journal of Sports Medicine,44(11), 787-793. doi:10.1136/bjsm.2009.070672

Quatman, C. E. & Hewett, T. E. (2009). The anterior cruciate ligament injury controversy: is ‘valgus collapse’ a sex-specific mechanism? Br. J. Sports Med. 43, 328–335.

Waldén, M., Hägglund, M., Magnusson, H. & Ekstrand, J. (2011). Anterior cruciate ligament injury in elite football: a prospective three-cohort study. Knee Surg. Sports Traumatol. Arthrosc. Off. J. ESSKA 19, 11–19.