Category Archives: Knee

The Long Femur and Squat Mechanics

The squat is one of the best exercises to improve performance, period. Athletes incorporate the squat into their workout regimen because it increases strength and power of the entire lower extremity and significantly activates the core muscles. Unfortunately, performing the squat improperly can lead to significant injury.
Without getting into too much detail, there are 4 main reasons why a person may not be able to squat with good technique.
 
  1. Poor ankle mobility, primarily dorsiflexion
  2. Poor hip mobility, primarily hip flexion and external rotation
  3. Muscle weakness/muscle imbalance of the lumbo-pelvic-hip complex
  4. Long femur (a high femur to torso length ratio or high femur to short tibia ratio)
 Three of the above can be fixed with corrective exercise. This might shock you but there is no corrective exercise program that will lengthen the torso and shorten your femur (yes, that is sarcasm). Unless you are skilled at removing portions of the femur with a chainsaw you’re not going to fix #4.
Squatting with a long femur can lead to low back injury. In the image here you can see that the individual with the long femur has an increased forward lean. The excessive lean increases load at the low back.
I love the video here. If you move to the 3:40 mark the video shows an individual squatting with long femurs squatting.

It drives me bonkers when a provider (athletic trainer, personal trainer, therapist, etc.,) attempts to correct a client’s squat mechanics by forcing changes in items 1, 2, or 3 when the real problem is the unfixable number 4. Before you waste a client’s running them through a corrective exercise program make sure it is something that can be fixed.
If you have a long femur to short torso ratio you do have options!
  1. Widen the stance
  2. Externally rotate the legs
  3. Raise the heels
 If you continue watching the video (around the 5:30 mark) you will notice how the individual’s squat mechanics are improved by making subtle changes in body positioning.

All of these options change the lever arms and evenly distribute the weight between the low back, knees, and feet. Thus, one joint is not excessively loaded more than the others. You can try adjusting one of the above items or mix and match any three of the above.
 

The Squat: Should Your Knees Travel Past the Toes?

Should the knees migrate past the toes when performing a squat? I posted this question on downloadsocial media, and the immediate response by most was “No!”. I expected this answer from most everyone, from novice to advanced lifters. To you, I happily say, you’re wrong! The debate on proper squat mechanics will never die, but I am going to steal a line from Randy B., an athletic training, and performance enhancement peer, who answered my question: “Absolutely, [the knees] should [go past the toes]. Don’t believe urban legends or follow sports med sacred cows!” I couldn’t have said this any better! Randy is spot on. This urban legend could lead to injury. The purpose of this blog is to shed some light on the debate and provide the rationale for proper squat technique.

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Knee Osteoarthritis and ACL Injury

ACLSix months (+/- a few) is the standard time needed for an athlete to return to competition following anterior cruciate ligament (ACL) surgery. To reach this date, therapy must be thorough and exact. Range of motion, neuromuscular control, or strength deficits that go unaddressed, negatively influence return to play and can also lead to other long-term consequences.

Those who suffer from ACL injuries are at greater risk of developing knee osteoarthritis (OA). Knee OA is a condition whereby the cartilage slowly wears away. This is a painful, life-long health issue that can lead to disability. With proper rehabilitation and adequate strengthening of the quadriceps, OA can be prevented. Sounds simple, but clinicians must also deal with arthrogenic muscle inhibition (AMI).

ASpinal tractMI is a neuromuscular dysfunction that limits the ability to strengthen muscle and is common following ACL surgery. With AMI, neurological signals from the quadriceps muscle to the brain and spinal cord are interrupted or slowed. You can read more about Brain and CNS deficits here.  So the question is, how do you combat AMI to properly strengthen the quad and subsequently prevent knee OA? The answer might be vibration training.

Vibration training employs a low-amplitude, low-frequency mechanical stimulation that exercises musculoskeletal structures. Vibration training provides strength gains without joint loading and stimulates osteoblastic and chondrocyte activity through the mechanisms of  Power Platemechanobiology. Subsequently, bone and joint health are improved.

A recent article by UNC’s EXSS Impact site found that vibration training (local or whole-body) improves quadriceps function by improving central nervous system function. Following vibration training, brain activity was altered in such a way that it became easier for these subjects to activate and use their quadriceps muscles. As such, muscle vibration can be an effective method to improve quadriceps strength and reduce the risk of developing knee OA.

Below is the full article from UNC.

Why did you do this study?

Individuals with anterior cruciate ligament (ACL) injuries are at greater risk of developing osteoarthritis (OA). OA is a considerable burden on the US healthcare system and contributes to physical disability and comorbidities such as obesity and diabetes. The lifetime cost of ACL injury amounts to $7.6 billion annually for patients that undergo reconstruction, $17.7 billion for patients that undergo non-surgical rehabilitation. Quadriceps dysfunction is ubiquitous following ACL injury and reconstruction, and is a major contributor to the development of OA. The quadriceps are responsible for absorbing impact forces during everyday tasks like walking and stair climbing, and also athletic tasks like running and jumping. When the quadriceps fail to act appropriately, their ability to attenuate these forces is reduced, and cartilage within the knee joint experiences greater loading. Subtle increases in joint loading are amplified through repetitive activities like walking, and over time, greater loading contributes to a gradual breakdown of articular cartilage.

Given the implication for future OA development, the restoration of proper quadriceps function is extremely important in rehabilitation. However, quadriceps dysfunction is caused by a neuromuscular phenomenon called arthrogenic muscle inhibition (AM), which presents a substantial limitation to muscle strengthening. Essentially, sensory signals from the knee joint inform the central nervous system – the brain and spinal cord – that the ACL as been injured. In response, our central nervous system responds by inhibiting the quadriceps to prevent further damage of the injured joint. While this mechanism may protect the joint in short term, AMI persists for many years following the initial injury and is thought to contribute to excessive cartilage loading and the development of OA. Therefore, strengthening the quadriceps is important in rehabilitation, but traditional exercises do not address AMI. Novel rehabilitation modalities are needed to combat AMI prior to the implementation of strengthening exercises.

Previous work in our laboratory indicates that muscle vibration provided directly (local muscle vibration – LMV) and indirectly (whole body vibration – WBV) may improve quadriceps function. However, what remains unclear is the mechanism by which these vibratory stimuli actually work to enhance muscle function. Given that AMI involves alterations in central nervous system function, it is imperative to understand how muscle vibration influences characteristics of spinal cord and brain function. Therefore, the purpose of this study was to understand how both WBV and LMV influence characteristics of central nervous system function.

What did you do and what did you find in this study?

Left - Transcranial magnetic stimulation to assess cortical neuron excitability; Right - Whole body vibration platform

We recruited subjects with ACL reconstruction for this study. First, we measured various characteristics of quadriceps function (i.e. strength and activation), and also how the brain and spinal cord contribute to muscle contraction. Following baseline measurements, subjects received an intervention of WBV, LMV, or control (no vibration) treatment. We repeated the same measurements of quadriceps function and central nervous system function following the treatment.

Active motor threshold was used to assess corticomotor excitability. In this case, both WBV and LMV lowered AMT relative to the control condition. This indicates that it becomes easier for the brain to activate the quadriceps following treatment. (* indicates P<0.0083)

We found that both WBV and LMV acutely improved quadriceps function (strength and activation) relative to the control treatment, and that this improvement was likely due to greater cortical neuron excitability. In other words, muscle contraction can either be voluntary (the brain tells the muscle to contract) or involuntary (spinal reflex loops). What we found was that following WBV and LMV, brain activity was altered in such a way that it became easier for these subjects to activate and use their quadriceps muscles.

How do these findings impact the public?

These findings indicate that vibratory stimuli acutely improve quadriceps function, and could be useful in addressing deficits in central nervous system function such as AMI. As such, muscle vibration could be an effective method to improve quadriceps strengthening protocols following ACL injury, and in turn reduce the risk of developing knee OA. Overall, knee OA is a major economic burden on the US healthcare system, and these findings could have important relevance for alleviating healthcare costs and physical disability.

A comprehensive rehabilitation program is vital for an athlete’s return to competitive sport. Failure to normalize range or motion, strength, and neuromuscular control can result in performance loss, reinjury, or long-term disabilities, such as knee OA. Make sure your rehabilitation program is inclusive of all components. Of course, the best cure for ACL surgery is preventing ACL tears all-together. If you want to prevent ACL injury, read about the RIDS Program designed to prevent injury. 

POS: Reduce Pain and Increase Performance

SwingDysfunction of one movement system can lead to a multitude of injuries. Treatment and care for one movement system can prevent our most common ailments. Most potential clients I interview complain of one or more of the following: sacroiliac joint (SIJ) pain and instability, non-specific low back pain (LBP), chronic hamstring strains or tightness, and peri-scapular and thoracic tightness or pain. Whether these complaints are isolated to one body part or involve many, the pain can typically be resolved by treating dysfunction of the Posterior Oblique Subsystem.

 

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RIDS Program: A New Paradigm for ACL Prevention

ACLThe grandeur of the World Cup is upon us. The world’s most popular sport has its chance to shine. As soccer gets its much deserved pedestal, summer camps fill. High school and collegiate soccer athletes become inspired. Training begins and with that begins the season of the ACL. With approximately a quarter-million ACL injuries per year, it is safe to say the injury is common in sport. Though most common in female athletes, ACL injuries happen to anyone anywhere, with soccer, basketball, and gymnastics athletes being at most risk.

While an ACL injury is traumatic in nature, the injury is rarely due to direct trauma. More than 75% of ACL injuries are non-contact in nature (1). Non-contact ACL injuries stem from a complex interaction of anatomical, hormonal and neuromuscular factors. Recent studies suggest that ACL injuries are caused by both neuromuscular fatigue and unanticipated movements commonly found in athletics, such as evasive maneuvers that involve some form of deceleration, change of direction, or landing. The coupling of these movements with modifiable risk factors (see graphic) is what leads to non-contact ACL injury. The good news is that non-contact ACL injury can be prevented by addressing these modifiable risk factors. Continue reading

A Runner’s Story: From Pain to Performance

Photo_shoot_runningIn 2010, I left clinical rehabilitation and performance training. While I love my current job, I do miss the clinical aspect, which is why I seize opportunities to take on random clients with complex issues.  I’ve never written about my clients, but this case is so common, yet complex, that I thought my readers might be challenged with similar clients/athletes, or might be experiencing similar issues themselves. Here is a runner’s story that went from marathon training, to painful walking and an inability to run. Her experiences with continued failed treatment and the road we have taken to get her back to training and setting personal records. Continue reading

Three Ways Ankle Sprains Cause Chronic Knee Pain

knee_patella_intro01The ankle sprain is the most common acute injury in competitive athletics, while the knee is the most chronically injured joint. Coincidence – I think not.

The question:

How does an ankle sprain lead to chronic knee pain, such as runner’s knee, jumper’s knee, Osteochondral defects, and/or general patellofemoral pain?

Three simple answers: Continue reading

ACL Injury: New Information on Prevention, Rehabilitation, and Consequences

I have written about knee injuries so much. Every day we are bombarded with research that quite frankly, it gets boring. The problem is with approximately a quarter-million ACL injuries per year, it is safe to say the injury is rampant. The devastating nature and commonality of the injury has provided loads of information on prevention, rehabilitation and mechanisms of injury. I am not going to regurgitate them all, but do want to share some recently published articles that sports medicine experts should read.

Article 1: Negahban, Et al. A systematic review of postural control during single-leg stance in patients with untreated anterior cruciate ligament injury. Knee Surgery Sports Traumatology and Arthroscopy, May, 2013.

I love systematic lit reviews and this SLR aimed to determine postural control on those with ACL injuries. We have many internal systems and senses that help us balance.  Beyond the use of our eyes and ears to sense balance, tiny mechanoreceptors and proprioceptors exist in our tissue that sense abnormal movement. This study found that when the eyes are closed individuals with ACL injuries had increased postural sway and loss of balance. This indicates that the injury and inflammation following injury inhibits our body’s internal mechanism to sense balance. When rehabilitating, be sure to emphasize proprioception exercises.

Article 2: Thomas, Abbey, et al.  Lower Extremity Muscle Strength After Anterior Cruciate Ligament Injury and Reconstruction. Journal of Athletic Training published online first, 2013.

Despite advances in rehabilitation and the numerous studies published on ACL rehabilitation protocols, we appear to be failing. This study shows that at 6 months Status Post ACL reconstruction that global weakness still exists. When comparing strength output from injured vs. uninjured legs it appears the knee-extensors (quads) and knee flexors (hamstrings) are weaker at 6 months when compared to the contralateral side. Conversely hip and ankle strength was not significantly different at 6 months. The timeline to return a player back to competition and activity is 6 months following activity and/or 95% strength of the uninjured side. This study indicates 6 months might be too early. Also, we may need to adjust our strengthening protocols to further stress knee flexion / extension strength.

Article 3 – Bell, DR, Clark, MA, Padua, DA, et al., Two- and 3-Dimensional Knee Valgus Are Reduced After an Exercise Intervention in Young Adults With Demonstrable Valgus During Squatting. Journal of Athletic Training published online first, 2013.

Darin Padua and the UNC Department of Exercise and Sport Science has done a lot of work on knee displacement and correlating the findings with ankle hypomobility and hip underactivity. This particular model used the NASM Corrective Exercise Model as the intervention procedure. This method systematically turns off hyperactive tissue and activates hypotonic tissues. The data revealed that following intervention of the ankle and hip medial knee displacement was significantly reduced.  This information is important as several studies have shown medial knee displacement to be a primary cause of ACL injuries and chronic knee pain.

Article 4: Ericksen, et, al. Different Modes of Feedback and Peak Vertical Ground Reaction Force During Jump Landing: A Systematic Review. Journal of Athletic Training published online first, 2013.

The inability of the body to absorb and control joint movement during high levels of ground reaction forces has been shown to increase risk of ACL injury as well as other chronic knee conditions.  This study evaluated the effect of expert provided and self-analysis feedback reduced peak ground reaction forces. This is not a paramount study but does shows the effectiveness of verbal queuing and observation to correct suboptimal neuromuscular control, specifically during landing and absorption of ground reaction forces through the kinetic chain. Rehab practitioners should incorporate feedback to teach clients appropriate muscle control during ACL rehabilitation.

I would like to say thank you to Darin Padua, PhD, ATC for keeping me abreast with current data. Darin is a leader in sports medicine research and specifically has many published papers on ACL injuries. Darin manages his blog site and also shares info on his twitter account. If you are a health and wellness professional seeking important information rehabilitation and prevention of injury, I recommend you give Darin a follow.

Cheers!

Knee Pain? Ignore it; Fix the Hip!

I have posted on this topic many, many times. Unfortunately, many still revert to antiquated rehabiltiation protocols. Thus, I feel compelled to keep talking about it.  If you or a client has knee pain focus on the hip, not the knee. There is so much data out there on linking decreased glute strength to knee pain. A weak or inhibited glute medius is unable to control femoral internal rotation and obligatory knee frontal plane motion.  These motions are a primary cause in knee pain – traumatic and acute. Today I discovered two, recently-published, systematic reviews to prove my point.

The first review examined 47 studies which looked at factors causing Patellofemoral Pain Syndromeknee_patella_intro01  (PFPS) (1). This review identified decreased muscle strength for hip abduction and hip external rotation as an important factor associated with the cause of PFPS. The pooled data also found increased Q-angle and sulcus angle to be factors – both of which have been linked to muscle imbalance.

The second systematic review was more specific by evaluating gluteal muscle activity – via EMG – and PFPS (2). The authors identified ten studies to be included in their review, with six of these studies considered to be high-quality and eight studies having a score of 8 or higher on the Downs and Black scale. The authors conclude there is moderate to strong evidence linking delayed or short Glute medius muscle activity to PFPS. The authors also state, “If gluteal muscle activation is delayed, frontal and transverse plane hip motion control may be impaired, leading to increased stress on the PFJ and subsequent symptoms associated with PFPS.”

Rehabilitation practitioners should note this when developing rehabilitation programs. Specifically targeting glute weakness and inhibition will limit hip internal rotation and obligatory knee frontal plane motion. Correcting faulty movement patterns will allow for optimal neuromuscular recruitment and joint kinematics, ultimately relieving or preventing pain.

If you are wondering which exercises will target the glute medius look at the study published in the recent JOSPT (3) and my recent blog titled “The Glute vs TFL Muscle Battle: Proper Exercise Selection to Correct Muscle Imbalance. The data represented in the JOSPT article demonstrate the bilateral bridge, unilateral bridge, side step, clam, squat and two quadruped exercises are best for activating the glute medius.

Are you ready to change your rehabilitation program?

References:

  1. Lankhorst NE, Bierma-Zeinstra, SMA, and van Middelkoop, M. Factors associated with patellofemoral pain syndrome: a systematic review.  Br J Sports Med.  2013;47:193–206.
  2. Barton CJ, Lack, S, Malliaras, P, and Morrissey, D. Gluteal muscle activity and patellofemoral pain syndrome: a systematic review. Br J Sports Med. 2013; 47:207–214.
  3. Selkowitz, DM, Beneck, GJ, and Powers CM. Which Exercises Target the Gluteal Muscles While Minimizing Activation of the Tensor Fascia Lata? Electromyographic Assessment Using Fine-Wire Electrodes. J Orthop Sports Phys Ther. 2013; 43(2):54-64.

The Glute vs TFL Muscle Battle: Proper Exercise Selection to Correct Muscle Imbalance

Reference:
Selkowitz, DM, Beneck, GJ, and Powers CM. Which Exercises Target the Gluteal Muscles While Minimizing Activation of the Tensor Fascia Lata? Electromyographic Assessment Using Fine-Wire Electrodes. J Orthop Sports Phys Ther. 2013; 43(2):54-64.

Overview and Introduction:
JandaSyndromesVladamir Janda revolutionized human movement dysfunction and rehabilitation when he described three compensatory movement patterns as a result of pattern overload and static posturing. Most musculoskeletal injuries are multifactorial, but more often than Janda’s described three compensation patterns – upper crossed syndrome, lower crossed syndrome and pronation distortion syndrome – are the key contributor to our pain complaints.

Since Janda introduced this topic research has continued to answer what and why questions surrounding these compensatory patterns. We have learned hypertonic / hypotonic muscles and the delicate interplay they have on integrated functional movement. Studies continue to show how these dysfunctional patterns lead to our most common injuries – PFPS, ITBS, Achilles tendinopathy, plantar fasciitis, epicondylopathy, biceps tendinosis, impingement syndromes, MTSS, etc.

As research evolves we continue to fine-tune our clinical decision making. For several years now rehabilitation journals have published articles linking a myriad of injuries to lower-crossed syndrome, gluteal inhibition, and over-activation of the tensor fasciae latae (TFL). We have learned that these should be a focal point in our rehabilitation techniques to resolve lower extremity overuse injuries. The article by Selkowitz, et al., in the Feb 2103 edition of JOSPT is unique and what I believe to be one of the most clinically relevant studies to be published in the last few months. I liked it so much I had to blog it.

Statement of the Problem:
A common descriptor associated with lower-crossed syndrome is femoral internal rotation and hip adduction. From a rehabilitation perspective we must enhance neuromuscular firing of hip abduction and external rotation. In addition we must inhibit over activity of hip adductors and hip internal rotators.

As a health care practitioner we understand the delicate interplay of functional anatomy. The problem is how do we inhibit a chronically hypertonic TFL while activating the hypotonic gluteal group if they both produce similar movements? It is a fine balance we must be cognizant of when designing rehabilitation programs.

This study examined which exercises elicit the greatest gluteal (medius / maximus) activation while minimizing activation of the TFL. This is exactly what we need to know when designing a rehabilitation program to target lower crossed compensatory patterns.

Study Methodology:
Electromyographic data of the gluteus medius and superior gluteus maximus was collected utilizing fine-wire electrodes on 20 healthy participants during the execution of 11 exercises.

Results:
Seven of the 11 exercises -bilateral bridge, unilateral bridge, side step, clam, squat and two quadruped variations – demonstrated statistically significant greater muscle activation in the gluteus medius and gluteus maximus when compared to the TFL. Side-lying hip abduction, hip hike, the lunge, and the step-up were either not significant or demonstrated higher TFL values compared to the gluteal group.

The authors ranked the exercises in order of highest gluteal to TFL ratios. Clam, side step, and unilateral bridge had the highest ratios, while lunge, hip hike, and squat had the lowest ratios.

Clinical Application of Data:
Altered arthrokinematics and muscle imbalances are a common cause of overuse injuries. Lower-crossed syndrome is a common compensatory pattern that is associated with hypertonicity of the hip flexors complex, which elicits altered reciprocal inhibition of the gluteal group. Targeting this dysfunctional pattern using proper exercise selection indicated here can prevent injuries, improve patient outcomes, and restore optimal function. When designing your program be sure to reference the material here to determine a proper rehabilitation program.

Limitations:
Studies are equivocal on reliability of surface EMG vs intramuscular. However, the authors cite using the method by Delagi and Perotto, which appears reliable. Still one has to question specificity and sensitivity to a minimal degree.

The participants were instructed on proper exercise technique. However, substitutions patterns are common in patients exhibiting muscle imbalance. Any slight deviation from proper technique can skew the data. I am curious how closely exercise technique was monitored and what occurred when deviation did occur.

Summary:
Like I said from the top, rarely do we have a published data with such clinical relevance. Studies that show how deep ultrasound penetrates a rats muscle are great, but clinically have little clinical utility. Data revealed here will guide decision making on proper exercise selection and ensure they are applying the proper strengthening exercise to specifically target the underactive glutes while avoiding the over active TFL. Kudos to the authors.

Foot Center of Pressure Reduces Kinetic Chain Dysfunction and Chronic Pain

If you read my blog before you are well aware that I am a big proponent of identifying human movement dysfunction and correcting functional imbalances to reduce chronic pain, such as knee osteoarthritis (OA), patellofemoral pain syndrome (PFPS), and low back disorders such as sacroiliac dysfunction, facet arthropathy, or generalized lumbago.

A few years ago I read about a new neuromuscular technique called AposTherapy.  For those unfamiliar, AposTherapy corrects gait abnormalities by retraining muscles to adopt an optimal gait mechanics. The primary goal of AposTherapy is to correct the foot center of pressure (COP) during gait. This is done by wearing a unique, foot-worn biomechanical device. At the time, I heard good results about the use of AposTherapy, but data was too young to consider valid just yet or share-able, just yet.

Recently, when looking at functional rehabilitation techniques for chronic knee pain I came across an interesting study in the Journal of Biomechanics the evaluates the benefits of AposTherapy, to correct kinetic chain dysfunction responsible for the development of knee OA (1). The results of the study were significant. Following the intervention patients demonstrated significant reduction in knee adduction (valgus) moment (KAM). Several authors have demonstrated KAM to be a primary cause of knee OA, including Miyazaki, who noted KAM correlates with the progression of knee OA (2). In addition, patients who participated in AposTherapy demonstrated increased walking velocity, reduced pain, and improvement of functional living (1).

The foot-worn biomechanical device alters foot COP, allowing for proper kinetic chain alignment neuromuscular efficiency. Clark and Lucett, noted that dysfunction at one joint precipitates altered movement patterns, at adjacent joints, both proximally and distally (3). This is the foundation of AposTherapy. By correcting  foot COP during gait, altered joint mechanics up the kinetic chain are nullified and neuromuscular efficiency is enhanced. Overtime, strength gains occur allowing for optimal gait patterns. Sharma, stressed the role of neuromuscular ineffciency, suggesting that secondary to elevated joint stress with higher impact loads and altered joint mechanics facilitate the pathogenesis of the chronic joint disease (4).

Biomechanical interventions focusing on foot COP, neuromuscular development and agility, enhance functional ability, reduce pain and increase spatiotemporal patterns of gait (1).  Working knowledge of human movement dysfunction and human movement compensation patterns are prudent to health practitioners.  Health practitioners should emphasize and correct human movement dysfunction when treating clients with chronic joint pain such as and certainly not limited to knee OA, PFPS, SI pain, and other  low back disorders like facet arthropathy.  Training to enhance neuromuscular recruitment, force-coupling, as well as the correction of altered length-tension relationships and poor joint arthrokinematics will go far in reduction of pain, prevention of chronic pain, and improved functional outcomes.

What techniques do you implement to train for optimal neuromuscular efficiency?

References:

1. Haim, A, et al. Reduction in knee adduction moment via non-invasive biomechanical training: A longitudinal gait analysis study. J of Biomechanics. 45 (2012) 41–45.

2. Miyazaki, T., Wada, M., Kawahara, H., et al. Dynamic load at baseline can predict radiographic disease progression in medial compartment knee osteoarthritis. Annals of the Rheumatic Diseases.  2002. 61, 617–622.

3. Clark, MA, and Lucett, SC. NASM Essentrials of Corrective Exercise Training. Lippincott, WIlliams and Wilkins. 2010.

4. Sharma, L., Dunlop, D.D., Cahue, S., et al. Quadriceps strength and osteoarthritis progression in malaligned and lax knees. Annals of Internal Medicine. 2003. 138, 613–619.

The Season Ending ACL

What is happening in the world of sports? Last week sports talk radio was abuzz over significant injuries to Derrick Rose and Iman Shumpert of the NBA. Now we lose yet another sports star – future hall of famer, Mariano Rivera of the New York Yankees – all three stars suffered ACL tears. This rash of injuries has created much debate on the issue. People are asking why? Did the shortened pre-season lead to this rise in injury? Did the condensed schedule lead to the injury? Are these just chance freak injuries? The answer to all is yes. However, each of these injuries could have been prevented.

Many original research studies and systematic literature reviews have shown a significant reduction in ACL injuries following implementation of neuromuscular training. In fact, a systematic literature review was recently published in the Journal of Bone and Joint Surgery (March 2012). This showed that ACL injury prevention programming provides a significant reduction in ACL injury. Many others literature reviews and research papers have also shown the effectiveness of neuromuscular training programs. A shortened pre-season may have led to the increased injury rate, because players were not exposed to the pre-season neuromuscular training. Unfortunately, not all teams apply injury prevention programming as part of the workout routine.

As for the condensed season schedule; a condensed season schedule with limited recovery dates will yield higher incidence of injury. A study published in the American Journal of Sports Medicine (2011) shows that injury rates in a short recovery group demonstrated a significantly greater overall injury rate, practice injury rate, and game injury rate compared to those in the extended recovery group. The injury rates were 6.2 times greater for overall injury, 4.7 times greater for game injury, and 3.3 times greater for practice injury in the short recovery group. That said, these injuries could have been prevented, even if neuromuscular training was not implemented during the pre-season. As the season progresses a gradual decline of neuromuscular efficiency occurs. This leads to the breakdown of mechanics and subsequent injury. ACL injuries can be prevented. Identifying faulty mechanics as the season progresses and then applying corrective techniques to fix those mechanics will go a long way in preventing non-contact ACL injuries.

The Geek’s Squat: Proper Squat Techniques for Strength and Injury Prevention

There has been much debate on proper squat techniques. Is it proper to maintain a vertical shin and prevent the knees from going beyond the toes? Is it better to squat and allow the knee to go beyond the toes? Proponents of the vertical shin technique argue it is best to save the knees and this helps increase posterior chain strength. Whereas proponents of parallel lines say, distribute the weight evenly and save the back. The purpose of this blog is to shed some light on the debate and provide the rationale for proper squat technique.

Early studies state that squatting with external loads causes undue stress and damage to soft tissue at the knee joint. This precipitated many experts to change squat mechanics. A vertical shin angle prevents excessive knee flexion, thus limiting the stress placed at the knee joint and potential damage to integral knee structures such as the meniscii, articular cartilage and ligaments. In addition, many state that maintaining a vertical shin angle allows for enhanced strengthening of the posterior chain (hamstrings, glutes, low back).

I agree it is important to protect the knees. However, the lower back is much more important, in my opinion. Low-back pain is one of the major forms of musculoskeletal degeneration seen in the adult population, affecting nearly 80% of all adults (1). It has been estimated that the annual costs attributable to low-back pain in the United States are greater than $26 billion (2). In addition, 6 to 15% of athletes experience low-back pain in a given year (3, 4). The body is an interconnected chain, and compensation or dysfunction in the LPHC region can lead to dysfunctions in other areas of the body (5). So why do we squat to protect the knees? How should we squat?

Proper squat mechanics requires optimal flexibility at the ankle, knees, and hips during the descent of the squat. When these joints are moving together, forces will be disturbed optimally and equally throughout the kinetic chain. If one of the joints has limited ability to move, another joint must compensate to make up for the lost movement. For example, if you are trying to pick something off of the floor and do not bend your knees you must bend at the back. Using this example, if we squat like this (limiting knee flexion or ankle dorsiflexion) we are asking the lower back to lift weight in a biomechanically disadvantaged position. You know the phrase “lift with your legs not your back.”

Do a quick check and test your squat mechanics. Evaluate your technique by watching in a mirror.  At the bottom of the squat the torso and tibia should be parallel to each other (See image below).  Have you ever noticed how a baby squats? Do a quick google search for baby squat. You will be amazed at their technique. They lift properly, because they have the flexibility to get in to a deep squat without excessive leaning at the low back. It does not matter if the knees go past the toes. The most important thing to ask: is the back parallel with the shin?

Fry et al. (2003) examined the hip and knee torque forces of variations of parallel squats and concluded appropriate joint loading during this exercise may require the knees to move slightly past the toes. Restricting squats created significant increases of excessive forward lean and subsequent increased torque loads at the low back and hip (6). Maintaining a vertical shank did not yield change knee torque significantly (6).

Torque is a measure of rotational force about an axis of rotation.  Simply put torque is a product of force and lever length from the axis of rotation to point of force of application (Τ = r x F) where Τ is linear torque, r is the displacement vector and F is force. Look at the two images below and notice the Torque values at the knee and low back:

Squatting with a Vertical Shin

Squatting with vertical shin:

Measurements:
αlb= 78° αk= 102° F = 135lbs (600.5 Newtons)
B to C= 19 inches (.48 meters). A to B = 2.75 inches (0.07 meters).  A to C = 16.25 inches (0.41meters)

Linear Torque Low Back:
Τlb = r x F
Τlb = 0.41m x (600.5N)
Τlb = 246.2 N·m

Linear Torque at the Knee:
Τk = r x F
Τk = 0.07m x (600.5N)
Τk = 42.04 N·m

Squatting to allow toes go beyond the knees

Squatting with parallel lines 
Measurements:
αlb= 90° αk= 90° F = 135lbs (600.5 Newtons)
B to C= 19 inches (0.48 meters) A to B = 9.5 inches (0.24 meters) A to C = 9.5 inches (0.24 meters)

Linear Torque Low back:
Τlb = r x F
Τlb = 0.24m x (600.5N)
Τlb = 144.12 N·mLinear Torque Knee:
Τk = r x F
Τk = 0.24m x (600.5N)
Τk = 144.12 N·m
You can clearly see that squatting with a vertical shin reduces stress placed on the knee, but significantly increases torque on the low back. Do we really want to place an increased load at the lower back, when it is so prone to injury? The most important thing to consider is overall exercise technique. Lifting with ideal posture is paramount for injury prevention. When this occurs forces will be distributed equally throughout the kinetic chain.

References:

1. Walker BF, Muller R, Grant WD. Low back pain in Australian adults: prevalence and associated disability. J Manipulative Physiol Ther 2004;27:238–44

2. Luo X, Pietrobon R, Sun SX, Liu GG, Hey L. Estimates and patterns of direct health care expenditures among individuals with back pain in the United States. Spine 2004;29:79–86.

3. Nadler SF, Malanga GA, DePrince M, Stitik TP, Feinberg JH. The relationship between lower extremity injury, low back pain, and hip muscle strength in male and female collegiate athletes. Clin J Sport Med 2000;10:89–97.

4. Nadler SF, Malanga GA, Feinberg JH, Rubanni M, Moley P, Foye P. Functional performance deficits in athletes with previous lower extremity injury. Clin J Sport Med 2002;12:73–8.

5. Powers CM. The influence of altered lower-extremity kinematics on patellofemoral joint dysfunction: a theoretical perspective. J Orthop Sports Phys Ther 2003;33(11):639–46.

6. Fry, A.C., J.C. Smith, and B.K. Schilling. Effect of knee position on hip and knee torques during the barbell squat. J. Strength Cond. Res. 17(4):629–633. 2003

Women are Wimps!!

STOP! Before you start throwing knives at my head I don’t really think women are wimps. If I did my wife would be waiting for me when I get home to prove me wrong. In fact, it is quite the opposite. Women have demonstrated continued increase in sports endeavors and are much faster, more aggressive and powerful than in past decades. However, secondary to the increased participation in sport, women are sustaining many more injuries.

Females between the ages of 15-25 years are most often injured, with the majority of these injuries are to the anterior cruciate ligament (ACL).  Females are 2-5 times more likely than males to sustain an injury to the ACL. This injury is primarily noted in basketball and soccer, but is still prevalent in many other sports such as volleyball, softball and gymnastics.  Women over the age of 25 are also more susceptible to recreational sporting injuries compared to males.  Many of these injuries are also musculoskeletal in nature, such as ankle sprains, shoulder tendinopathy, and chronic knee pain such as chondromalacia, PFPS and ITB Syndrome. Looking at the glass half-full though,most of these injuries can be prevented with correction of movement dysfunction.

With the increased participation in sport and the commonality of musculoskeletal injuries it is prudent to understand typical movement dysfunction patterns that bring about these injuries.  Secondary to genetics, body morphology and muscle recruitment females are susceptible to lower extremity impairment syndrome.

Lower extremity impairment syndrome is a combination of muscle imbalances, joint dysfunction, and poor muscle recruitment patterns from the low back to the foot. The impairment syndrome can be characterized by foot pronation, knee valgus, femoral internal rotation, and lordosis at the low back.  When performing functional activities, such as running or cutting, these characterizations are amplified. Ultimately, this leads to ACL tears or the aforementioned chronic pain syndromes.

The good news is these poor biomechanical patterns can be corrected following focused rehabilitation techniques designed to improve muscle synergy as well as joint mechanics. Many studies have been done to show a significant reduction in the incidence of injuries, such as ACL tears, by correcting these impairments. If you are having chronic pain in the lower extremity, it might be a result of lower extremity impairment. This is a good thing, because it can be corrected.