Monday, March 14, 2016

How to Eliminate Pathokinematics - Part VI

Last week we covered several different types of training methodologies that can be employed including the use of manual resistance/perturbations and plyometrics.  This week, we are going to cover a vital concept that we all know a lot about.....Squats.  No matter what your thought is on squats, good, bad or ugly, they are a foundational movement of life.  From our first ability as an infant to squat prior to walking to our ability to maintain our ability to reduce our risk for falling as a senior citizen.  Squats are essential.  Although we all know a lot about them, the intention of this blog is to put us all on the same page about them so that when we are training for movement, we are all looking at the same thing when it comes to the ability to squat.

Squats and the Basics

Strength, endurance and co-contraction of the quadriceps and hamstrings are absolutely essential for maximal performance and injury prevention in movement for sports as well as the activities of daily living.  The one exercise that has been “proven” in the research to not only aid in creating co-contraction between the quadriceps and hamstrings, but also to improve vertical jump is the squat. 

Squats have been a highly controversial weightlifting method for a number of years.  Health care professionals have often considered squats more harmful to the low back and knees than beneficial.  Therefore squats have often been discouraged if not avoided completely despite the fact that they are so commonly used in most well developed exercise and sports performance exercise routines.  Some of this controversy arose from the assumption that squats place large shear stresses at the knees as well as excessive loads on the lumbar spine. 

This original misconception was created in the early 60s from a paper published by KK Kline in which he showed that squatters had inherently greater laxity in their medial and lateral collateral ligaments than non-squatters.  This was measured by a non-validated device and resulted in KK Kline making the assumption that repetitive squatting with resistance led to greater laxity of the medial and lateral ligaments.   Despite the fact that this original research has been debunked by decades of research since then, many orthopedist and those in musculoskeletal care still make the assumption (assumption since not based on the science) that squats are bad for your knees.

So, if that assumption is true, why are squats good for us?  For one thing, there is a great deal of research in the last 10-20 years that clearly shows that the shear stresses at the knee and the excessive loads on the lumbar spine are actually lower than previously thought and mimic those forces people experience with daily activities.  Weight training exercises can be divided into two broad categories: open kinetic chain and closed kinetic chain exercises, as discussed previously.  Open kinetic chain exercises are used for isolation, in which the body part is not in contract with a surface.  An example of this we used earlier is seated leg extension.  Here the feet are not in contact with the floor and this exercise is used for isolation of the quadriceps.  This is considered a less functional form of exercise because it is training the body to work in a fashion in which it does not normally work during daily activities or sports.  During sports, the leg rarely has to extend itself against a weight in an open chain situation and therefore this type of exercise does not have a high carry over to sports. 

The other type of exercise is considered closed kinetic chain when the body part is in contact with a stationary surface.   The squat, as mentioned before, is an example of this type of exercise.  Here we are training the body in the same ways it functions in the course of daily activity and in sports.  During this exercise, the muscles of your legs, back, stomach and upper body are co-contracting to provide stability to all segments.  These types of activities have a high carry over to daily activities like sitting in a chair, getting out of the car, ascending and descending stairs, jumping for a rebound or driving an opponent back in football.

Any exercise, if performed incorrectly, can result in injury.  With squats, it is very important to keep the following key techniques in mind throughout the course of the exercise:

  1. Never use more weight than the athlete can handle.
  2. Always maintain a neutral pelvic position throughout the exercise and keep the abdominals tight – this is often the limiting factor in how much weight an athlete can use.
  3. Never allow for a lateral shift to one side or the other during the squat – this results in asymmetrical loading of the back, hips, knees and ankles.  This type of loading pattern (seen in the example cited earlier in the section on Repetitions to Substitution) increases stress to one side while reducing the strength needed on the other.  It is imperative to watch for this compensatory strategy.
  4. Avoid letting the knees pass over the toes in the descent to the squat position – this adds shear stress to the patellafemoral joint.  Although there might be slight anterior positioning of the knees to the toes this should be minimized with a proper hip hinge.
  5. Keep the feet shoulder width apart with your feet slightly toed out – do not toe out too far due to the fact that this increases shear stress in the sacroiliac joint.
  6. Never place plates under the feet – this shifts the weight line forward adding increased stress to the spine and adding to tightness of the gastrocnemius.
  7. Never allow the knees go in toward the mid-line during ascent or decent.  This is a classic compensatory strategy for individuals with identifiable weakness of the gluteus medius.  Allowing the athlete to continue doing this when squatting simply reinforces this weakness.
  8. Stop if at any time the athlete experiences back pain and re-evaluate the squatting form.  If the pain is not eliminated, have the athlete evaluated by a qualified health care professional before continuing with squats.
  9. Never progress to the next level until the most basic form of squat has been mastered.
Squats do not have to be done with super heavy weight in order to facilitate strength gains.  Technique should be emphasized over weight although all too often the exact opposite is the case.  Remember that every rep that is done with poor technique (lateral shift, adduction toward midline, etc) is 3 reps that must be done to train the proper motor pattern.

Squat Neuromuscular Retraining (SNMR)

Our research indicates that 80% of athletes fail the Full Squat Test (FST) used in a movement assessment.  This is despite the fact that many of them may be performing squats as a part of their regular exercise routine.  Because of this alarming statistic, teaching the proper squatting motion is the essential first step before beginning or continuing a squatting routine.  It is essential to development of maximal force production as well as preventing injury. 

We define failing this test as a  ≥1” lateral shift to either side of the mid line (as depicted in this Olympic athlete here).  This lateral shift typically happens when an athlete is unaware of the proper mechanics involved in squatting, or when an athlete began squatting with poor mechanics that were never corrected.  In the latter case, through years of training the athlete has reinforced poor (incorrect) motor plans and abnormal proprioception into the system.  To this athlete, “off-center” movements feel normal.  However these deficits result in significant asymmetries in the way the tissues bear the load, which results in asymmetrical strength gains and force production and an increased potential for injury.  Although we describe this as a lateral shift, recent papers have described this motion as lateral displacement of the pelvis during the squatting motion.  What these papers describe is for all intents and purposes a lateral shift.

Squat Neuromuscular Retraining (SNMR) is the starting point for most athletes to improve squat mechanics.  This exercise is performed with a mirror and the subject is initially given lots of verbal and tactile cueing to prevent lateral shift, spinal rotation, or any other pathokinematic movements.  Have the subject perform the squat just prior to the point of lateral shift or other breakdown in form.  Once he or she starts to shift, or the form disintegrates in some other way, correct the athlete with verbal and tactile cueing back to the midline and proper body position.  Have the subject hold this position for 5 seconds. Return to the starting position and immediately have the subject return to the same position as in the previous repetition, attempting without cueing.  If the subject is unable to obtain the proper position during ascent or descent, cue and have them hold again for 5 seconds.  Have the athlete perform 20 repetitions with a 5 second pause.  After a short rest, have the athlete repeat the squat in front of the mirror, this time attempting to descend to a lower level without a shift or other change in form.  This exercise is typically performed over 2-3 sessions before the subject is able to perform a proper squat without cueing.  SNMR should also be a part of the home exercise program as well, where the athlete performs 3-4 sets of 20 reps with 5-10 second holds.  We will revisit this exercise in the Corrective Exercise Progression.

Another more aggressive technique that can be employed with this exercise is the SNMR with
perturbations.  In this scenario, the athlete performs 20 full squats.  during the 20 squats, we are not too concerned about the lateral shift that occurs during these 20 as we will address this in a moment.  At the conclusion of the 20 reps, the athlete gets into a end range of motion squat with their hands out in front of them.  The position of the arms is in full extension and the palms are palms are pressed together firmly to the point that they feel their pecs engaged.  While remaining in the squatting position, you quickly position them into a neutral squatting position.  Then you do perturbations throughout their entire kinetic chain including at the hips, knees, arms (in rotation and diagonal) all while avoiding anterior and posterior.  The key with these perturbations is not to "break them" but rather to challenge them to the point just before failure.  This is immediately followed by another 20 more reps and repeating of the perturbations.  This can be done for 2 to 3 sets.

This is a very aggressive form of training but also a very effective form.  One thing athletes will always tell you is that neutral position feels weird.  This sense of weirdness comes from proprioceptors and a system that has been trained that an abnormal position is normal.  Anything outside of that will feel odd.  So, this training methodology takes several neural concepts into consideration.  First is that proprioceptors fatigue.  Second is that once in this fatigued state they can be re-trained by over stimulating the entire system with proprioceptive input (perturbations).  If employed correctly AND if the athlete is doing this as a part of their home exercise program, this will be corrected in 2-3 visits.  If not, then you should re-evaluate the "root cause" of the problem to determine if there is a better fit intervention.

Full Squats and Jump Squats

Performing full squats (to 90 degrees of flexion and higher) and jump squats are both considered  more advanced routines and therefore maintaining “healthy” knee/hip alignment is essential during these activities.  It is imperative to follow the repetitions to substitution concept described above when embarking on a routine that involves full squats and/or jump squats. 

It is also absolutely vital that technique be a focus with these exercises.  You are training for performance, muscle memory and motor planning.  Bad training technique adds to decreased performance as well as weaknesses that can lead to injury.  With squats, common tightness in many athletes can lead to the heels coming off of the floor and the knees protruding over the toes, particularly as the squat deepens.  Training with this form can lead to tightness of the gastrocnemius and excessive shear stresses in the knee (patellofemoral joint).  Therefore, it is essential to help the athlete keep the heels in contact with the floor throughout the exercise and the knees behind the toes at the end range of motion. 

Common weaknesses in athletes can also result in a squatting technique where the athlete shifts more to one side than the other in a lateral shift (see the sections above on Repetitions to Substitution and SNMR) and/or where the knees come in toward the mid-line during ascent or descent.  Shifting can aid to increased fatigue of the leg, which takes the majority of the load in this instance and therefore can increase the potential for injury.  Knees coming in toward the mid-line add to increased stress to the ligamentous structures of the knee, increased stress to the illiotibial (IT) band and lumbar spine.  Finally, some squatters are tempted to excessively toe out their feet.  This position, especially in females, places a tremendous stress through the sacroilliac joint and can be a major source of low back pain.  To determine your natural foot position, march in place for 10 seconds and stop while noting the position of your feet (this should be your natural toe out position).    

With the jump squat, weakness in the lumbopelvic region and ankles can again add to the knees to coming together at the mid-line.  These weaknesses and improper form also add to a “hard” landing rather than a “soft” landing when jumping.  Hard landing adds to decreased force attenuation (shock absorption) and increased stress to ligamentous structures.  By bending the knees slightly at impact there is more shock attenuation, less force and therefore less fatigue with a corresponding reduced potential for injury.  

Dr. Nessler is a practicing physical therapist with over 17 years sports medicine clinical experience and a nationally recognized expert in the area of athletic movement assessment.  He is the developer of an athletic biomechanical analysis and author of a college textbook on this subject.  He serves as the National Director of Sports Medicine for Physiotherapy Associates, is Chairman of Medical Services for the International Obstacle Racing Federation and associate editor of the International Journal of Athletic Therapy and Training. 

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