Study Title: Does cervical muscle strength in youth ice hockey players affect head impact biomechanics?
Authors: JP. Mihalik, KM. Guskiewicz, SW. Marshall et al.
Journal: Clinical Journal of Sport Medicine
Date: September 2011


Summary:

• Some of you are aware that Hockey Canada recently instituted their new Head Contact Rule in an attempt to minimize head and neck injuries, including concussions. While I think this is certainly a giant leap in the right direction, there are also many other factors to consider when it comes to injury prevention. In this particular study, Mihalik and his group of researchers looked at the role of more "internal factors" for head injury prevention, specifically cervical muscle strength. The rationale for this paper was based on the speculation that the neck can be strengthened to reduce the risk of mild traumatic brain injuries by way of tension to withstand and distribute the force of head impact.
• This prospective cohort study utilized AAA hockey players (aged 15 + 1 year) wearing helmets equipped with Head Impact Telemetry to record impact force data (linear, rotational and HIT severity profile) in real-time. Using a handheld dynamometer, body relative cervical muscle strength (as described by Kendall) of the anterior neck flexors, anterolateral neck flexors, cervical rotators, posterolateral neck extensors, and upper trapezius were measured. These results were then used to categorize the players into three groups based on strength (weak, moderate and strong) for the purposes of comparative analysis.
• Of the 7770 total impacts recorded over the course of one season, it was revealed that increased isometric cervical strength did not reduce the severity of head impacts. In fact, those players with weaker upper trapezius muscles experienced lower impact severity scores than those with the strongest recordings.
• Personally, I am not prepared to discredit the role of neck strengthening as a potential protective mechanism but I do think some things (relevant to this aspect of injury prevention) need to be considered. First, I am not quite sure how the results from a shrugging maneuver (as used to test the upper trapezius) can be relevant regardless of the findings. I would put more weight into those results from each of the other testing procedures. Second, I'm more of a quality of muscle activation kind of guy rather than a quantity. Does quantity matter? Of course, but I do think that the ability to reflexively stabilize a joint upon impact is more important than absolute strength. I would liked to have seen Janda's and Jull's tests rather than the ones used. Finally, we should remember that the results of this paper are demographic specific. At this age, the players are not only still developing physically, but they are also still learning the art of both rendering and receiving contact. Therefore, I would like to see a similar study performed at higher levels and at the very least, in junior age players.

Mihalik, JP et al. (2011). Does cervical muscle strength in youth ice hockey players affect head impact biomechanics? Clinical Journal of Sport Medicine, vol 21(5); 416-421

Study Title: Spine stability: Lessons from a balancing stick
Authors: NP. Reeves, KS, Narendra & J. Cholewicki
Journal: Clinical Biomechanics
Date: 2011

Summary:

• Reeves does it again! This paper here was a continuation of his "Spine Stability" series of papers and although not an actual study, was an excellent "lecture" piece. Coming off of his Six Blind Men & the Elephant paper where he looked at the role and importance of robustness (or variability) for both static and dynamic stability , Reeves uses a simple object, a stick, to provide us with a conceptual, but comprehensive lesson in spinal stability. In this paper, he walks us through five different "lessons", all pertaining to a stick (or two) being balanced, to help us look further into the information necessary to stabilize the spine, noise in control and spine performance, spine evolution for stabilization and efficient control, control delays and spine performance, and the role of goals for spine control. All pertaining to feedback control.
• His first experiment examined the role tracking plays in stability through positive and negative feedback. It was discovered that inorder to balance a stick in the hand effectively, one must possess both position and velocity related feedback. The lesson from this was that the central nervous system monitors both position and velocity during spinal movement for each degree of freedom (rotation and translation about each axis) it possesses. Its significance? That muscle spindles, especially of the deep musculature, play an important role by measuring both muscle length and rate of change for spinal stability.
• His second experiment examined tracking into more detail by looking at precision. Using similar concepts to the image above, he placed a weight on the top of the stick for one trial and down at the bottom for the next to understand angular displacement and velocity. It was realized that balancing the stick with a weight at the bottom created a larger "gain" (or necessary force) to maintain equilibrium and as such, the lesson was learned that impairments in tracking the spine will impair control and may lead to non-optimal recruitment patterns. Therefore, the relevance of this was that not only is position-related feedback important but also velocity related feedback for spinal control.
• The third experiment looked into controllability and observability. Using two different trials of stick balancing (one with two sticks in series - on top of each other - and the other with two sticks in parallel - beside each other), it was revealed that multiple masses will have different movement characteristics. The lesson from this experiment was that independent control of the various spine segments through its physical make up and neural recruitment may be important for feedback control and subsequent stability, as well as metabolic efficiency.
• His fourth experiment examined delays in feedback control. By utilizing multiple trials with various stick lengths, it was revealed that shorter sticks make balancing more difficult due to an increase in size and rate of oscillation. He attributed this to delays in feedback control. The relevance? In rapid dynamic environments, feedback control may negatively influence spine control, especially in the low back pain population.
•  The final experiment was more of an observation looking at various control strategies. Realistically, there are many different ways to balance a stick and so for any given task, there will likely be an infinite number of possible feedback gains to provide stability. Ultimately, the objective should be to respect the goals of the system (or the person) whether it be for maximizing performance or minimizing costs. The takeaway from here is that the central nervous system should learn the dynamics of the spine system and that neuromuscular retraining may be valuable to help "reset control to a more desirable strategy".

• We must remember, however, that this was a "lecture" piece rather than an actual clinical trial or review. The principles in this paper are quite sound but as always, more rigorous research in these topics must be performed especially with humans as subjects.

Reeves, NP. et al. (2011). Spine stability: Lessons from a balancing stick. Clinical Biomechanics, vol 26; 325 - 330

Study Title: Rehabilitation Exercise Progression for the Gluteus Medius Muscle With Consideration for Iliopsoas Tendinitis
Authors: MJ. Philippon, MJ. Decker, E. Giphart, MR. Tory, MS. Wahoff & RF. LaPrade
Journal: American Journal of Sports Medicine
Date: 2011
​
Summary:

• This paper is a MUST READ for rehabilitation and training professionals working in ice hockey, especially those of you in the "show". As you know, Dr. Marc Philippon is one of the world's leading hip surgeons and like the physician you refer your athletes with problematic hip injuries to. Published in AJSM, this paper looked identified the most appropriate EARLY postoperative hip exercises following hip surgery. With consideration of the fact that the Iliopsoas tendon occasionally becomes irritated or inflamed with early rehabilitation, the Dr. Philippon and friends utilized EMG to determine which of 13 exercises were most appropriate and when. To sum up the results, the exercises that demonstrated the highest peak gluteus medius muscle activation were the single-leg bridge, the prone heel squeeze, and the side-lying hip abduction (either performed with internal hip rotation, against a wall, or with external hip rotation). In comparison, the supine hip flexion, side-lying hip abduction with external rotation, and hip clam exercises  demonstrated moderate iliopsoas muscle activation. As a result, the exercises with the best ratios (high gluteus medius activity vs low iliopsoas activity) were the prone heel squeeze, single-leg bridge, and the side-lying hip abduction with internal rotation. Please note that all exercises were then classified into their most appropriate phase of rehabilitation: I, II, or III.
• What really caught my attention with this study was the lack of discussion pertaining to optimal and controlled muscle activation of the core musculature in general. It is my assumption that proper progression of early rehabilitation will respect optimal core control and integrity and subsequently optimal iliopsoas activity. It is difficult for me to swallow that those professionals adhering to proper progressions and appropriate rehabilitation principles actually elicit unwanted and increased iliopsoas activity. That said, this study must have been warranted and therefore must speak volumes of the rehabilitation protocols currently prescribed.
• Overall, I really enjoyed this paper and certainly walked away with a better understanding of EARLY postoperative gluteus medius and hip rehabilitation.

Philippon, M. et al. (2011). Rehabilitation exercise progression for the gluteus medius muscle with consideration for iliopsoas tendinitis. American Journal of Sports Medicine, Vol. 39(8); 1777-1785

Study Title: Breathing Evaluation and Retraining as an Adjunct to Manual Therapy
Authors: L. McLaughlin, C.H. Goldsmith & K. Coleman
Journal: Manual Therapy
Date: 2011

Summary:

• Here's a short little study that evaluated the presence of poor respiratory chemistry in patients suffering from neck and low back pain, as well as the efficacy of biofeedback training on chemistry, pain and function. If you are a frequent reader of this blog then you'll know that trunk muscles have a dual postural stability and respiratory function. You'll also know that the presence of poor respiratory control may result in faulty thoracic, cervical, and scapular mechanics. Well the authors of this paper took a series of 29 cases with neck and/or back pain who failed conservative outpatient manual and rehabilitative therapy and studied whether or not they possessed poor respiratory chemistry.  Such (poor) chemistry was identified via a capnograph which measures CO2 levels at the end of a normal exhale.
• Respiratory retraining was the main intervention in this study, consisting of awareness training, capnograph feedback, and manual therapy to improve mobility. Not only did the results demonstrate that all 29 patients possessed below normal ETCO2 levels, but outcome measures recorded improved in all patients following the intervention.
• While most, if not all, of you probably do not own a capnograph, this study does provide good evidence that 1) many of your patients suffering from neck and/or back pain probably also have some level of poor respiratory control, and 2) pain levels can improve following a clinical intervention that includes both respiratory training and manual mobilization.
• Unfortunately however, most physical therapy, chiropractic, athletic training, and massage therapy programs don't include respiratory training techniques in their educational curriculum. 

McLaughlin, L. et al. (2011). Breathing evaluation and retraining as an adjunct to manual therapy. Manual Therapy, 16; 51-52.

Study Title: Diagnostic Imaging for Low Back Pain: Advice for High-Value Health Care from the American College of Physicians
Authors: R. Chou, A. Qaseem, DK Owens et al.
Journal: Annals of Internal Medicine
Date: 2011

Summary: 

• My full review of this paper was recently posted on Research Review Service but since I feel strongly about its message, I thought it would be a good idea to provide you with a brief introduction. In concert with the high incidence of low back pain in today's society lies a relatively high rate of requisitions for diagnostic imaging of neuromusculoskeletal conditions pertaining to the lumbar spine. Unfortunately, the appropriateness of such imaging studies may be questionable at best for many of these conditions owing to the fact that the outcome of care often leads to similar results in those patients who have undergone "routine" imaging and those who have not regardless of whether such tests were performed. Certainly, such imaging may be required for those patients suffering from severe and /  or progressive neurological deficits as well as for those presenting with serious underlying conditions however, more often than not, those patients presenting in general family, chiropractic or rehabilitation practices may do well without the unnecessary doses of radiation and costs to the health care systems. This best practice advice paper provided by the Clinical Guidelines Committee of the American College of Physicians provides the medical reader with a summary of the current literature pertaining to the utility of diagnostic imaging for low back pain and advises on the rationale behind evidence-informed decision making when a patient presents with low back pain symptoms. Utilizing results from high-quality studies, suggestions are made for cost worthy diagnostic protocols and advice is given on the potential harms and benefits of radiological procedures. Additionally, a valuable summary for patients has also been provided of which can be easily accessed here.

R. Chou, A. Qaseem, DK. Owens et al. (2011). Diagnostic imaging for low back pain: Advice for high-value health care from the american college of physicians. Annals of Internal Medicine, 154; 181-189

Study Title: Medical Therapies for Concussion
Authors: W. Meehan
Journal: Clinics in Sports Medicine
Date: 2011

Summary:

• Here is a little review of potential interventions in one of the most influential and highly discussed injuries in ice hockey today, concussion. While the current state of the literature may still be in its infancy, each incident of this "traumatic brain injury", particularly in professional hockey, seems to make front page news and cast a shadow of doubt on the safety of our sport. This paper by Meehan discusses various therapeutic options that may be rendered in the presence of such injury.

• First introduced is the role of physical rest in the recovery process. The stepwise return to play protocol is discussed although it is mentioned that studies have begun investigating the role of light physical activity during recovery. Since quantitative cognitive deficits have been demonstrated in the presence of such injury, academic accommodations via cognitive rest were suggested for student athletes.

• Often considered an "invisible injury", Meehan proposes that education regarding the typical recovery process be one of the mainstays of therapeutic intervention. Studies have demonstrated fewer symptoms at follow up in those that were informed about their symptoms, coping strategies, and the likely course of recovery.

• While most athletes achieve spontaneous recovery of symptoms within days to weeks, some experience prolonged recovery to which pharmaceutical intervention may be warranted. It should be noted that the evidence for such interventions is very minimal and the following information should be taken as a summary rather than a recommendation of care. Meehan suggests that pharmacologic treatment only be considered in the presence of the following:

1. Symptoms exceeding the typical recovery period,
2. Symptoms negatively affecting quality of life to the degree that the treatment benefits outweigh its risks, and
3. The clinician rendering treatment is both knowledgeable and experienced in the management of (sport) concussion.

• Meehan asserts that pharmacologic treatment has yet to be demonstrated to speed the recovery process and that standard approaches are lacking. Instead, he reports that medications are utilized for the treatment of its signs and symptoms. Since previous literature has grouped symptoms related to sport concussion in the categories of sleep disturbance, somatic (i.e. headache), emotional, and cognitive, chosen medications must be specific to the symptom experienced.

• In the presence of sleep disturbance, sleep hygiene that includes the elimination of constant stimuli (i.e. television, computers, caffeine, etc) is strongly considered. Medically, Meehan's first line of defence for the presence of sleep disturbance is Melatonin. Other considerations are discussed although benzodiazepines seem to be advocated against due to their negative arousal and cognition effects.

• Somatic symptoms such as headaches are common in the presence of sport concussion. Meehan discusses the potential roles of antidepressants (i.e. amitriptyline - his preferred treatment) as well as the potential negative effects ("rebound") of analgesics such as ibuprofen. Other medications are introduced as well as physical therapy, psychotherapy, and trigger point injections.

• For athletes suffering from emotional disturbance, for example stemming from participation restrictions, Meehan suggests tricyclic antidepressants and serotonin reuptake inhibitors as a complementary intervention to coping strategies, familial support and psychological counseling.

• Finally, since cognitive symptoms are common complaints in those suffering from sport concussion, potential pharmacologic treatment may include methylphenidate for attention and speed processing deficits as well as the domaminergic agent amantadine for executive function and prefrontal cortex glucose metabolism, in addition to cognitive rehabilitation.

• It should be noted that the majority of athletes recovery both spontaneously and quickly from sport concussions. The preceding review merely discusses potential medical interventions that may have complementary roles to physical and cognitive rest and rehabilitation. It must be reiterated that the above MUST NOT be taken as prescription but merely as a review of Meehan's academic paper, intended for medical professionals. If you or your family member has sustained a concussion, you MUST consult a physician for care.
  

Meehan WP. (2011). Medical therapies for concussion. Clinics in Sports Medicine, 30; 115-124.

Study Title: Reinjury After Acute Posterior Thigh Muscle Injuries in Elite Track and Field Athletes
Authors: N Malliaropolous, T Isinkaye, K Tsitas & N Maffulli
Journal: American Journal of Sports Medicine
Date: February 2011

Summary:

• Through one simple omission, this article provides little value. As you may be aware, the biarticular nature of the hamstrings seems to put this muscle group at higher risk of strain than monoarticular musculature. Since previous research has demonstrated reinjury rates as high as 34%, the objective of this cohort study was to determine whether a specific clinical assessment may be able to provide indicative factors of possible reinjury following an acute hamstring strain. 165 elite track and field athletes with first-time strains were evaluated in this prospective study. The specific clinical assessment utilized was a 4-grade classification system of hamstring injury based on active range of motion (AROM) - the greater the AROM deficit, the greater the severity of injury. Interesting classification system if you ask me! All athletes followed the same standardized plan of management following their injuries although the rehabilitation protocol was not described. Based on this classification system, it was revealed that athletes who suffered a grade II hamstring strain demonstrated a significantly higher risk of reinjury than those who suffered a grade I, III, and IV injury.
• Unfortunately, the results from this study mean very little to me since the rehabilitation protocol administered was not provided. One of the highest risk factors for reinjury is previous injury so it is clear that in non-contact sports, many rehabilitation and sport conditioning professionals are missing the boat when it comes to return to play. Therefore, in my opinion, a grading system based on AROM has little value compared to a well designed return to play rehabilitation and conditioning strategy as it pertains to minimizing the risk of reinjury following acute hamstring strains in elite track and field athletes.

Malliaropolous N et al. (2011). Reinjury after acute posterior thigh muscle injuries in elite track and field athletes. American Journal of Sports Medicine, 39(2); 304-310

This recent paper by Gabriele Wulf and colleagues investigated the potential factors involved in motor skill learning. Particularly focusing on the influence several variables may have on the learning and performance of specific motor skills as they pertain to the medical field, a review of the literature was performed. Fortunately, the following factors may be applied to a wide range of settings and be of use by those in education, rehabilitation, and sports performance...to name a few. It was suggested that learning can be particularly enhanced when the learner's motivation is optimized.

Learning: "a relatively permanent change in a person's ability to perform a skill"

OBSERVATIONAL LEARNING

• In combination with physical practice, observational practice has been demonstrated to contribute highly to the acquisition of motor skills via mutual activation of the cerebellum, cingulate gyrus, inferior parietal lobe, premotor cortex, and supplementary motor area. The combination of such observational and physical practice is said to provide the opportunity to both extract important information pertaining to coordinated motor patterns as well as evaluate effective strategies that otherwise would be difficult if one were to both prepare and execute simultaneously. Therefore, observation provides the opportunity to "process". Additionally, alternating between observation and physical practice (performing a dyad) allows the learner to observe and apply. This facilitates enhanced motivation.

ATTENTION FOCUS

• This variable pertains specifically to movement in relation to space and time. Ideally, attention should be directed to the induction of an external focus in contrast to one that is internal. Through simple changes in cues utilized, performance and learning can greatly be enhanced. For example, instructing a patient to "thrust his/her pelvis to the ceiling" will performing a glute bridge would be a more effective cue than suggesting he/she "activate the glutes and extend the hips". Similarly, greater gains will likely be witness in a training environment when asking a squatting athlete to "sit back onto a chair" as opposed to "flex your hips keep your tibia vertical". This external focus has been shown to facilitate automaticity of movement  and the use of unconscious processes, therefore reducing unwanted attentional demands.

FEEDBACK

• Commonly pertaining to "knowledge of results" and "knowledge of performance", feedback has been demonstrated to highly influence motivation. Specifically when provided following "good" trials, feedback is said to facilitate more effective learning through positivity. Further, normative feedback, that is, feedback in relation to the performance of others (or the norm), enhances self-efficacy and motivation. This is true even in such instances when feedback was false (i.e. saying "great job" - even though performance was relatively poor). Therefore, rather than providing neutral information, positive feedback in specific situations will enhance self-fulfillment and motivation, thereby affecting learning.

PRACTICE THAT IS SELF-CONTROLLED

• Providing the learner with the opportunity to control their practice conditions has been demonstrated to be an effective method for the learning of motor skills. Allowing the learner to dictate when or when they do not want to receive feedback seems to be of greater importance than frequency of feedback. Additionally, occasionally permitting the individual to decide when they choose to practice facilitates greater active involvement and subsequently, enhanced motivation, self-control and effort. Such practice and learning conditions may also pertain to free play (allowing the athlete to spend extra time in the weightroom, court, or ice) and recreational exercise (performing rehabilitation exercises at home or in the gym).

As you can see, there are no shortage of methods for us as rehabilitation and exercise professionals to become more effective "teachers". In utilizing some of the above principles in the strategies we employ, we may become more effective practitioners and facilitate better means of motor skill acquisition.

Reference: Wulf G, Shea C & Lewthwaite R. (2010). Motor skill learning and performance: a review of influential factors. Medical Education, 44; 75-84