Therein lies a correlation between the brain and body that is a direct result of an interdisciplinary approach to understanding sports science. Beyond the programming is an interaction of disciplines closely examining the chaotic nature of our being. With The Rebel Movement blog, our mission is to investigate and further the science and philosophy of motor performance. Through our collaborative approach of skill acquisition and movement analysis, we will provide thought-provoking content applicable to athletes, coaches, researchers, and practitioners. Your feedback is vital to the blog’s mission, so please feel free to provide your thoughts, comments, and considerations. We look forward to building a stronger foundation for the sports science community.
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.8This 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.
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 – firstname.lastname@example.org
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Here are recent (2019) recommended readings as they pertain to some of the factors surrounding the ecological approach to motor learning. Likewise, we’ve developed a basic schematic to help your basic understanding of how psychology has evolved. By no means is this a complete picture.
– what does the research state on strength training and injury?
– what are some fundamental resistance exercises that an adolescent athlete should be introduced to and perform?
– what is a proper way to regress / progress a strength exercise?
Let’s dive in…
In my opinion, the introduction of sports into a youth’s life should coincide with an introduction to strength training. You may be thinking, “my (insert age) child should be lifting weights? Isn’t that dangerous?” It’s actually quite the opposite. Under proper supervision, a strength training program may offer an adolescent athlete a multitude of physical, emotional, and psychological benefits (Faigenbaum, 2009). Overall, it appears that 8-12 weeks of resistance training can improve overall strength by 30-50% in youth athletes (Dehab & McCambridge, 2009).
For the sake of scope, let’s focus our attention on the effects of strength training for reducing injury risk in this population. So what does the research tell us? One of the earliest studies completed on strength training and injury rate was by Hejna (1982). High school athletes were divided into three groups: weight training during the pre-season and in-season, weight training year-round, and a control, non-strength training group. The researchers found that athletes who participated in weight training had an injury rate of 26.2%, while the control group’s injury rate was 72.4%. If an injury were to occur, the control group took approximately 2.4 times longer to rehabilitate from injury compared to their strength training counterparts.
After 8 weeks of resistance and plyometric training, 27 female high school athletes demonstrated improvements in neuromuscular and biomechanical movement qualities that suggest these athletes were at less risk for ACL injury (Lephart, 2005). Specifically, the athletes demonstrated increases in quadriceps strength during dynamometer testing and greater muscular activity in the gluteus medius bilateral vertical jump (Lephart, 2005). Additionally, athletes displayed increased hip and knee flexion during the jump-landing maneuver (Lephart, 2005). In a meta-analysis by Sugimoto (2015), across 14 reviewed studies, strength interventions reduced the risk of ACL injury by 68% in youth female athletes. A larger meta-analysis by Lauersen, Bertelsen, & Andersen (2014) provide additional evidence for strength training to reduce injury risk, as “strength training reduced sports injuries to less than 1/3 and overuse injuries could be almost halved”. So the question becomes, what specific strength exercises should youth athletes complete? From multiple investigations, it appears that even the addition of bodyweight exercises can have a significant impact on injury risk. Keep in mind that bodyweight exercises are a form of resistance training! Walden (2012) incorporated unilateral/bilateral squats, glute bridges, lunges, planks, and jump-landings, resulting in a 64% reduction in ACL injury. Similar exercises were incorporated into a warm-up for female youth soccer athletes, resulting in a 77% reduction in knee injury rate (Kiani, 2010).
The basis of strength training for adolescent athletes is mastering basic movement patterns that are transferable to a multitude of more complex resistance exercises. We want to ensure that our athletes are not adding strength to dysfunction, which can lead to many future issues. A requisite for every adolescent (and any athlete for that matter) is demonstrating proper form in the following “fundamental” exercises: hip-hinge / Romanian deadlift, body-weight squat, forward/backward lunge, push-up, pull-up/inverted row, and over-head press.
In addition to form, proper exercise progression is a must for younger athletes, as these motor patterns are very much malleable and quickly receptive to adaptation, for better or worse. Here’s an example of a squat exercise progression that I have found quite successful with youth athletes:
2) body-weight squat (may add box behind athlete)
3) squat with a PVC pipe
4) goblet and/or resistance band squat
5) unloaded barbell back/front squat
6) loaded barbell back/front squat
Again, I cannot stress the following enough: do not add strength to dysfunction. If your athlete cannot adequately perform a barbell squat, there is no benefit to adding further load to this movement. Similar progressions can be made for any upper or lower body compound exercise. Sometimes that will include the use of resistance bands or partners (e.g. assisted pull-ups), TRX equipment (single-leg squats, inverted rows), or the training center itself (wall assisted push-ups). To reap the most benefits of strength training program, youth athletes should be participating in a strength program at twice per week at a minimum (Behm, 2008). It is beyond the scope of this post to discuss the physiological adaptations to resistance training, but athletes need to be consistent in their training to obtain build resiliency within the musculoskeletal system. Loading the system in a sensible and progressive manner throughout our young athletes’ sporting careers will provide the opportunity for maximal performance, but more importantly, will keep them on the field.
If you’re looking to dive deeper into the literature regarding strength training for adolescent athletes, I highly recommend these position papers:
Behm, D. G., Faigenbaum, A. D., Falk, B., & Klentrou, P. (2008). Canadian Society for Exercise Physiology position paper: resistance training in children and adolescents. Applied Physiology, Nutrition, and Metabolism, 33(3), 547-561.
Dahab, K. S., & McCambridge, T. M. (2009). Strength training in children and adolescents: raising the bar for young athletes?. Sports Health, 1(3), 223-226.
Faigenbaum, A. D., Kraemer, W. J., Blimkie, C. J., Jeffreys, I., Micheli, L. J., Nitka, M., & Rowland, T. W. (2009). Youth Resistance Training: Updated Position Statement Paper From the National Strength and Conditioning Association. Journal of Strength and Conditioning Research,23(Supplement 5), S60-S79. doi:10.1519/jsc.0b013e31819df407
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
Kiani, A. (2010). Prevention of Soccer-Related Knee Injuries in Teenaged Girls. Archives of Internal Medicine,170(1), 43-49. doi:10.1001/archinternmed.2009.289
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.
Lephart, S. M., Abt, J. P., Ferris, C. M., Sell, T. C., Nagai, T., Myers, J. B., & Irrgang, J. J. (2005). Neuromuscular and biomechanical characteristic changes in high school athletes: a plyometric versus basic resistance program. British Journal of Sports Medicine, 39(12), 932-938.
Sugimoto, D., Myer, G. D., Foss, K. D., & Hewett, T. E. (2015). Specific exercise effects of preventive neuromuscular training intervention on anterior cruciate ligament injury risk reduction in young females: Meta-analysis and subgroup analysis. British Journal of Sports Medicine,49(5), 282-289. doi:10.1136/bjsports-2014-093461
Walden, M., Atroshi, I., Magnusson, H., Wagner, P., & Hagglund, M. (2012). Prevention of acute knee injuries in adolescent female football players: Cluster randomised controlled trial. BMJ,May 3(344). doi:10.1136/bmj.e3042
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!
At coaching clinics, the pens whip out when the speaker demonstrates a new drill. Everyone is anxious to write down that drill that will make the big difference.
Countless times, high level coaches are asked, “What drill can we do to fix our …”
Doug Beal and Russ Rose have been asked about what drills they use. In similar answers, both profess to use only a few drills with many variations.
What are the magic drills that make those teams so good?
Big secret; it’s not the drills. There is no magic.
If simply running the drills made you great, everyone could buy Al Scates drill book (like I did once upon a time) and we’d all be awesome, because his teams were awesome. Blindly running Coach Scates’ drills didn’t make a difference for my team. If his drills didn’t work, whose would?
Looking at it another way; two great teams run different drills, and they end up playing each other in the championship. How can different drills work in attaining the same goal?
Certainly athletes make a difference. Some years you have superior athletes and you win. Some years you have great players yet you lose to superior talent. Let’s set talent aside for a bit, despite that having superior players is likely the most important ingredient to winning matches.
If it’s not the drills, what is it?
Probably a mix of a few common principles, applied to everything in the program. A few to start with;
Understanding. The players learn to understand why they are using a skill, running a drill, doing things in a specific way. I hear and I forget. I see and I remember. I do and I understand.
Specificity. Hundreds of top coaches say this repeatedly; you need to practice what you want to do. EXACTLY what you want to do. Coaches don’t toss in games; players don’t hit under the net; there are very few perfect passes. When game-time comes, you will have to pass, set, hit, dig and block every odd thing that comes your way. So it must be practiced that way; randomly.
Flexibility. Sometimes, you might win with serving. Sometimes with defense. Maybe with outside hitting. Playing to your strengths (whether your favorite skill or not) is your best strategy. Also flexibility within a drill; one drill with many options is better than 20 drills with no options. They already know the drill, you’ve just tweaked it to work on the thing you need most. Finally, flexibility with a system. You may not have the players to run the system you like; you need to run the system that suits the players.
Continuous learning. Mick Haley chose to speed up USC’s offense. Russ Rose chose to swing block (and then didn’t, and then did again.) He is reportedly an avid reader. John Dunning shuffled his lineup and changed systems after losing a key player. If those guys are still learning, can’t we all?
Most importantly, we need our teammates on the same page. Good teams have a system for siding out, playing in transition, serving, defense, and for being out-of-system. They work together. And they understand what their teammates are going to do in each of those playing systems. When you have common ground and understanding of everyone else’s role, your role makes sense, and you can perform it, or change it to fit what the opponent is throwing at you. Drills might guide teams toward working on a specific skill; the team’s common ground lends to success in any drill.
There are certainly drills that are better than others. Specific and game-like and random are a good start. Great teams can get better in any drill with those ingredients, because they have taken the time to learn the “whys”, and to understand.
Why does this work
How can I know something sooner
Why does this happen after that happened
Why do I need to be here, not there
Carl McGown liked to say, teach them where to look, and teach them how to move. Shortly after, if not woven into those tasks, you have to learn why. If you know why it works, you likely already have the drills you need to succeed.
Random IMPACT is a bi-monthly education column in the Badger Beacon, an award-winning newsletter published by the Badger Region.
BJ LeRoy is a CAP Cadre member, board member and coach from the Badger Region. He also helps administer the Facebook group Volleyball Coaches and Trainers. You can reach BJ at email@example.com.
Hope you all enjoy this one. We’ve got plenty more lined up, stay tuned. Once again, if you’d like to write for our blog, feel free to email either one of us. If you have any comments, suggestions, or concerns, please feel free to contact us. Thanks!
Here’s a list of five accessible articles we thought are a good start, must read, and of course are classics within the Biomechanics and Motor Learning literature. Throughout the year, we’ll continue to share articles grouped within themes that are applicable to all.