Monday, August 10, 2020

Poor Movement = Decreased Athletic Performance - Part III

Last week we began to discuss the impact that poor movement has on athletic performance.  We concluded our discussion by looking at the impact that poor movement (pathokinematics) has on power generation.  We continue that discussion looking at the impact on power.

In addition to increasing the amount of force that can be produced by a muscle or muscle group, when we improve length/tension relationships, we also increase the efficiency of movement.  With an increase in efficiency in movement comes decreased time to produce the movement, as well as an increase in the force that is able to be generated.  Without any change at all to cardiovascular output, efficiency and endurance, if we simply increase the ability of the muscle to produce more force with less energy demand, in a shorter period of time, not only does power in the pure sense increase, but overall endurance improves as well. 

There are a lot of standardized tests to assess muscular power in athletics but the two most commonly used are the Sargent Jump Test and the Stair Sprint Test.  The Sargent Jump Test was developed by Harvard’s gymnastic coach, Dudley Sargent in the early 1900s and it is still used today as an assessment of power output and maximal vertical height (it is also known as the Vertical Jump Test).  There are some variations to the test.  But in the most basic form, the athlete stands next to a wall sideways, reaches up with the arm closest to the wall fully extended, keeping the feet flat on the floor, and the highest point at which the fingers tips reach up on the wall is marked.  Then the athlete performs a maximal vertical jump marking the point at which the finger tips reach at the peak of the jump.  This is performed 3 times and the average of the three is calculated.

The Stair Sprint Test has been found to be highly reliable and valid for measuring explosive power and is endorsed by the American College of Sports Medicine.  In this test, the athlete is timed while sprinting a given distance on ascending stairs.  The force is the athlete’s weight and the time is how long it takes to ascend the given distance.  In this particular test, the athlete improves, i.e., increases his or her power output, by decreasing the time it takes to ascend the stairs.

It is easy to see the effect that movement patterns would have on the Stair Sprint Test when we look at another example.  Using the Step Up Test to assess an athlete’s movement pattern, we can see that when this particular athlete ascends (steps up) the right hip falls into an adducted position and the right femur rotates internally.  When this occurs, two things happen:  First, there is an immediate loss of energy in the kinetic chain.  Second, these changes in the stepping up action alter the length/tension relationships in the lower body.  Since this test is designed to demonstrate efficiency of movement (or lack thereof) and a corresponding maximal use of energy, each of these occurrences has a dramatic impact on power output.  In the position in which we see this athlete, the muscles cannot contract maximally and much of the explosive power she needs to climb the stair is lost.  Test results show a longer length of time to complete the task or movement as a result. 

In sports, speed and power are sometimes used interchangeably.  Speed is defined as distance traveled per unit of time.  From a calculation standpoint, the only difference between a speed calculation and a power calculation is that the power calculation takes the athlete’s weight into account, or the weight of an object that is being moved by the athlete.   We can easily see then the impact that abnormal movement or pathokinematics has on power.  Therefore we can deduce that pathokinematics in this, or any, athlete would similarly impact speed due to the loss of energy in the kinetic chain and the inability of the muscles to contract maximally and generate the greatest amount of explosive power in the shortest amount of time.

Flexibility

Flexibility is simply the ability to move your muscles through their full range of motion.  Factors that influence flexibility include:

·       Heredity
·       Age
·       Gender
·       Mode/level of activity
·       Internal tissue temperature
·       History of injury (scar tissue, altered bony structure)
·       Pain

Since the late 80’s or early 90’s there has not been much research conducted on factors that influence flexibility or how we can influence flexibility with training.  Even so, in a clinical and athletic training setting we do see the impact that pathokinematic movement patterns have on flexibility.  If, for example, an athlete has a significant lateral shift with a squat, then this movement pattern is going to be carried over to every squatting motion he performs, outside of sports and during sports.  This includes such activities of daily living as sitting down on a chair, sitting on his bed, sitting and rising from the commode, and getting in and out of a car.  As a result of imbalances in the body during this movement alone, overall flexibility will be greatly affected, which of course translates to performance.  We know that flexibility is critical for all sports and many athletic trainers, coaches and other professionals who work in the field of athletics believe that for the total time spent, flexibility training may in fact be the most important and the most beneficial activity across all sports.

Looking at one of our previous examples, we can easily see how pathokinematic movement can increase tightness in the body from the core down, reduce flexibility and contribute to an ever increasing reduction in performance.  This athlete, performing the squat test, is clearly shifting to the right, as shown previously.  He is also unable to keep his back in alignment while bearing most of his weight on the right side.  This shift is lengthening the hamstring and the quadriceps on the left and shortening them on the right, as shown.  This means that over time, he is likely to become less flexible on the right side of his body than he is on the left.  This further reinforces the shift, making it worse over time in a vicious cycle.  In addition, due to this particular abnormal movement and the associated inflexibility and abnormal force attenuation it causes in the lower kinetic chain, it is likely that this athlete will also become much less flexible in the lumbar spine, and eventually also in the thoracic and cervical spine.  This can lead to imbalances in running gait, excess (and inefficient, energy zapping) motion in the hips, pain in the L5/S1 region of the lower back, pain traveling up the back into the mid and upper back and neck, and compromised power output through the transmitting core. 

A couple of last points related to flexibility in this example that are worth noting is first that as a part of his abnormal movement or pathokinematics, this athlete’s arms move forward as he squats.  He does this as a compensatory strategy in order to prevent himself from falling over.  So, not only is his inflexibility adding to abnormal force attenuation, it also adds to a loss of balance as well.   Again, this further increases the loss of kinetic energy and ultimately decreases the efficiency of the entire system.  Over time, this athlete is likely to become more and more inflexible in the hip flexor group as well, which is critical for football and other activities of daily living such as walking and running as discussed above.  These factors related to flexibility can ultimately lead to other kinds of injuries and pain with activity down the line.  Of course we can also easily see the performance impact limited mobility has on speed, power and endurance on the football field.

I hope you found this information valuable.  Next week, we will continue our discussion on how movement can impact balance and control.  As always, I appreciate all our followers and hope you find the information we provide useful in your practice with your athletes.  If you do, please follow me on instragram @bjjpt_acl_guy and Twitter @acl_prevention.  I also just launched a new website, www.drtrentnessler.com.  My vision is to create a movement revolution in the world of ACL rehab.  Check it out, hear more about my story and where we are headed.  Train hard and stay well.  #ViPerformAMI #ACLPlayItSafe


Dr. Nessler is a practicing physical therapist with over 20 years sports medicine clinical experience and a nationally recognized expert in the area of athletic movement assessment and ACL injury prevention.  He is the founder | developer of the ViPerform AMI,  ViPerform AMI RTPlay, the ACL Play It Safe Program, Run Safe Program and author of a college textbook on this subject.  Trent has performed >5000 athletic movement assessments in the US and abroad.  He serves as the National Director of Sports Medicine Innovation for Select Medical and movement consultant for numerous colleges and professional teams.  Trent also a Brazilian Jiu Jitsu purple belt and complete BJJ/MMA junkie. 

Monday, August 3, 2020

Poor Movement = Decreased Athletic Performance - Part II

Last week we introduced the concept that poor movement (pathokinematics) negatively impacts athletic performance.  We will continue that discussion looking at the impact that pathokinematics has on movement efficiency and energy.

Efficiency, Energy Conservation and Endurance

Another way that pathokinematics, or movement that falls outside the norm can impact performance is by increasing the amount of energy required to move the body in order to perform the function or participate in the sport.  If the system is working properly, the limbs are controlled easily and efficiently and the least amount of energy is used to move the body---to walk or run.  However, simple tightness or weakness in any part of the body can have a dramatic effect on the quality and efficiency of movement and therefore the energy required to move a certain distance within a certain amount of time.  This is often seen when there is hip flexor tightness.  During the running cycle, one of two things happens.  They shorten their stride length to compensate for the tightness (makes running less efficient) or they rotate in their lumbar spine to make up for the lost motion (which can lead to low back pain).

Of course if natural stride length is shortened, as in the walking/running example, it also takes more steps to travel the same distance, and consequently more energy.  This lost energy cannot then be used to extend the time of exercise or the speed of leg turnover in running or walking.  Sometimes, only one hip flexor is tight, which can cause the stride length to be asymmetrical.  Such asymmetry also decreases the efficiency of movement, and again more energy is required to travel the same distance.  So, it is not only more difficult to move when moving the body in “unusual” ways, but it also takes longer to move the body the same distance at any given speed.  Both the increased difficulty and the increased length of time it takes to move require additional energy expenditure.

Muscular endurance is defined as the ability of a muscle or group of muscles to sustain repeated contractions against resistance for a sustained period of time.  Factors that influence endurance are:

·       VO2 Max – also known as “maximal oxygen uptake,” is a measure of the maximum ability of the body to transport and use oxygen during a specific period of time while engaged in intense exercise

·       Lactate Threshold – the exercise intensity at which lactic acid starts to accumulate in the blood stream, sometimes referred to as anaerobic threshold 

·       Exercise Economy – the efficiency of the technique (movement) the athlete has in his or her respective sport

Improvements in the first two factors come with endurance, power and cardiovascular training.  However, improvement in exercise economy (which is impacted by the quality of movement) has a direct effect on efficiency and consequently, energy conservation.  In the walking/running example above a simple improvement in stride length can result in improved efficiency of the movement and entire system, leading to less energy expenditure, which results in improved athletic endurance---in this case, the ability to run for a longer period of time before having to stop.  This is where a good running assessment and orthopedic assessment come into play.  Getting someone who knows not only how to assess your running gait but also performing a detailed orthopedic exam to see where the limitations are that may be leading to your altered running gait.  

 Power and Speed

Power is defined as the rate of work being done per unit of time.  In athletics, we calculate power equal to force over time (P = F/T) or the amount of time that it takes to move an object (a weight, sled, bike or your body weight) a given distance.  Power can be increased by either increasing the amount of force applied or by reducing the amount of time it takes to move the object.  So, improvement in power output can be influenced in two ways: increasing force or decreasing time.

Pathokinematics have just as big, or perhaps an even bigger relationship to power output than pain, efficiency, energy conservation and endurance.  To explain this, we must first talk about muscles and specifically, length and tension relationships.  

Muscles work in a length and tension relationship.  There are optimal lengths at which muscles produce the maximum amount of force (see the graph above).  If a muscle is in a position that is shorter or longer than this optimal position, then the strength or force that the muscle can produce is decreased.  Take for example, the bicep curl exercise.  When someone performs a bicep curl, there are stages during the motion that the exercise is more or less difficult.  Typically greater effort is required at the beginning of the curl and at the end of the curl.  Your bicep is strongest in the mid-range of the motion, and so it is at this point that the least amount of energy is required to move the weight or curl the arm upward.  It is at this point that the tension the muscle is able to produce is at its highest, relative to its length, and therefore this is the optimal range of motion in which the bicep can produce the most force. 

This same concept carries over to all other body movement.  Abnormal movement patterns or pathokinematics move the body, including all its joints, ligaments, tendons and muscles outside the “optimal” range.  Length/tension relationships in the muscles are drastically altered when we move abnormally and consequently, less force can be produced by the muscles.  To illustrate this point, let’s take a look at the following example. 

The young man in this photo is a football player who is having difficulty performing in his sport following an injury.  Performance tests such as the vertical jump and 40 yard dash show a marked deterioration as compared to his pre-injury results.  He has been performing squats as a part of his rehabilitation and training routine in order to strengthen the injured limb and thereby improve his performance results.  However, he is having difficulty understanding why he continues to have such a large strength deficit on the left side.   When we view his squat, it is apparent to even the casual observer that there are several issues that might contribute to such a strength deficit on the left side and the resulting decrease in performance on these performance tests as well as on the football field.  

When we consider length/tension relationships, we know that if asymmetrical movement patterns like the one seen in this photograph are not corrected, none of this athlete’s muscles from the lower back down will ever be as strong as they could be, nor will they be able to produce as much power as they would in a more symmetrical movement pattern.  Part of his overall weakness is actually the result of weakness in his right side as well as his left.  The right, in this example, will always be worked more than the left due to the marked weight shift to that side, which obviously causes more of the load burden to be borne on that side.  However, because there is also a dramatic change in the length tension relationship on that side, the right side will never be as strong as it would be either if the exercise was performed correctly.  Because of the high degree of shift, his left quadriceps is put in a lengthened position while the right is in a shortened position.  His left gluteus medius and maximus are put in lengthened positions and his right in shortened positions.  So, as stated before, even though his right might be stronger, it will not be as strong as it could be until these length/tension relationships are corrected and the athlete is able to access and use the ranges in which his muscles can produce the maximum amount of force.

I hope you found this information valuable.  Next week, we will continue our discussion on how movement can impact performance on certain tests.  As always, I appreciate all our followers and hope you find the information we provide useful in your practice with your athletes.  If you do, please follow me on instragram @bjjpt_acl_guy and Twitter @acl_prevention.  I also just launched a new website, www.drtrentnessler.com.  My vision is to create a movement revolution in the world of ACL rehab.  Check it out, hear more about my story and where we are headed.  Train hard and stay well.  #ViPerformAMI #ACLPlayItSafe


Dr. Nessler is a practicing physical therapist with over 20 years sports medicine clinical experience and a nationally recognized expert in the area of athletic movement assessment and ACL injury prevention.  He is the founder | developer of the ViPerform AMI,  ViPerform AMI RTPlay, the ACL Play It Safe Program, Run Safe Program and author of a college textbook on this subject.  Trent has performed >5000 athletic movement assessments in the US and abroad.  He serves as the National Director of Sports Medicine Innovation for Select Medical and movement consultant for numerous colleges and professional teams.  Trent also a Brazilian Jiu Jitsu purple belt and complete BJJ/MMA junkie. 

Monday, July 27, 2020

Poor Movement = Decreased Athletic Performance

Throughout the history of this blog I have submitted that pathokinematics negatively affects athletic performance.  I have examined in depth how pathokinematics contribute to injury in athletes, looked at the types of injuries we see in athletes who demonstrate certain kinds of lower extremity pathokinematics and reviewed several other factors, some seemingly unrelated to movement itself, that affect athletes and which can contribute to pathokinematics.  Here I will dive into more detail about how pathokinematics affect several fundamentals that drive performance.

 Pain During Activity and Sports

The first and most obvious way in which pathokinematics can affect performance is the fact that certain kinds of pathokinematics lead to injury over time.  Injury often brings pain, and even when an athlete is ready to return to sports activities, he or she may have recurring pain with the activities that directly or indirectly involve the body part that was injured.  Additionally, he or she might have pain when involved in activities where the movement patterns are the same as when the injury occurred, since those movement patterns were likely to have contributed to the injury in the first place.

Let’s look at a specific example.  The human body is designed to function in a given way as we have discussed previously.  When we allow our bodies to operate outside the “norm,” movement becomes less efficient, requires more energy, and can result in tissue break down and injury over time.  To illustrate this point, let’s look at the human gait, which is the way we walk.  

Gait occurs in humans thanks to a spinal reflex (located in the spinal cord in the “central pattern generator”) and occurs in a predictable and repetitive pattern.  First, the heel strikes or contacts the ground with the foot slightly supinated and then the foot pronates to the point of mid-stance, at which time all of the weight of the body is centered over the foot.  Next is the “toe off” in which the foot continues to pronate to allow push off on the 1st ray (big toe).  The foot, ankle, knee, hip and spine all work together in harmony during each of these defined phases in order to facilitate forward (in this example) movement of the body while in a standing, upright position.  These structures have certain ranges of motion specifically designed to allow our joints, ligaments, tendons and muscles to absorb the force of these actions in ways that are not detrimental to the structures themselves over time and with repetition. 

An athlete (or walker as in the example above) with excessive tightness of the hip flexors (iliospoas)   This has two effects.  First there is a decrease in the extension of the hip which causes a decrease in stride length.  A decrease in stride length which means a shorter stride, less distance covered per stride and less force is produced and force absorbed.  Because the stride is shorter and less distance is covered for every foot strike, this means performance is impacted.  Since there is less absorption of ground reaction forces in the lower limb, this means greater risk for injury.  Less force absorbed in the lower limb means that force (which does not change) is absorbed further up the chain or in the sacral and lumbar spine.  This pattern of decreased hip extension is often  associated with a compensatory increase in spinal extension and rotation in the lumbar spine.  When this occurs, we can observe several motions at the hip.  Excessive rotation (transverse plane motion) and excessive anterior and posterior tilt (sagittal plane motion) can be observed at toe off on the side where there is a decrease in stride length.  The result of this type of motion in the transverse plane is excessive shear wear on the articular surfaces in the lumbar spine, especially in the areas of the L5/S1 vertebrae.  It is well documented that articular cartilage is weakest when subjected to shearing forces and therefore this can be a source of lower back pain for runners and walkers. This lack of hip extension can also lead to weakness of the gluteus maximus on the involved side.  As a powerful hip extensor, if the hip does not go into full extension, then this muscle can not achieve its maximal strength potential.

Weakness in the gluteus medius muscle of the hip can further contribute to lower back pain in this population because weakness in this muscle can lead to excessive hip motion in the coronal plane (side to side and up and down).  So in the example above we can see a direct link between pathokinematic movement (excessive hip motion in both the transverse, sagittal and coronal planes) in runners and walkers that can lead to pain (lower back in this case), which exponentially increases the likelihood of decreased performance.   Obviously, the greater degree of pathokinematics we see in an athlete, the greater the likelihood of more significant amounts, degrees and durations of pain, particularly during times when speed and/or endurance requirements are high.

Estimates are that 80% of the population suffers from one form or another of low back pain and consequently this type of problem affects many athletes and decreases their ability to perform.  The most common area for low back pain is in the region of the intervertebral disc at L5/S1, which is often caused by wear directly attributable to pathokinematic movement in the lumbar spine and hip seen in runners and walkers.  So, whether it is the ability of an athlete to sustain speeds and run long distances without pain or the ability of an athlete to get into and stay in the aero position on a bicycle, low back pain will dramatically impact performance.  Of course, it is obvious that low back pain would also be a limiter in lifting sports, bending sports or sports that require full body speed and agility, such as basketball and volleyball.  A particularly notable sport in which athletes often complain of lower back pain is golf.  Often when looking at a golf swing, we see tightness in the hip flexor muscles that cause lower back issues over time. 

For a good dynamic hip flexor stretch, try this stretch to help prevent lack of hip extension.  




I hope you found this a valuable series.  As always, I appreciate all our followers and hope you find the information we provide useful in your practice with your athletes.  If you do, please follow me on instragram @bjjpt_acl_guy and Twitter @acl_prevention.  I also just launched a new website, www.drtrentnessler.com.  My vision is to create a movement revolution in the world of ACL rehab.  Check it out, hear more about my story and where we are headed.  Train hard and stay well.  #ViPerformAMI #ACLPlayItSafe


Dr. Nessler is a practicing physical therapist with over 20 years sports medicine clinical experience and a nationally recognized expert in the area of athletic movement assessment and ACL injury prevention.  He is the founder | developer of the ViPerform AMI,  ViPerform AMI RTPlay, the ACL Play It Safe Program, Run Safe Program and author of a college textbook on this subject.  Trent has performed >5000 athletic movement assessments in the US and abroad.  He serves as the National Director of Sports Medicine Innovation for Select Medical and movement consultant for numerous colleges and professional teams.  Trent also a Brazilian Jiu Jitsu purple belt and complete BJJ/MMA junkie. 

Monday, July 20, 2020

Does Sport Specialization Increase Risk For Injury - Part II

Last week we looked at a study by McGuine et al Am J Sport Med 2017.  In this study, the authors showed that if an athlete specializes in a sport that they are more likely to suffer a lower extremity injury than athletes who do not specialize.  As a parent or coach, we may push our young athlete to specialize in sport thinking that this is going to help them perform better in the sport and increase their likelihood of succeeding in that sport.  What that means is different for everyone.  It may mean that they just perform better or that they make the varsity team or that they will improve the likelihood that they will get a college scholarship.  At the same time, many of us do not realize we are actually putting them at great risk for injury.  According to Rugg et al Am J Sport Med 2014, if an athlete suffers a knee or ACL injury prior to a division I career, they are 8 times more likely to suffer a knee injury or ACL injury during their Division I career.  This pure fact is preventing some university's from recruiting athletes with a previous knee history.  So, instead of helping our athlete, we may actually be jeopardizing their chances for a athletic scholarship.

What if I told you that athletes that specialize actually do not play better than athletes that play multiple sports.  Sound counter intuitive doesn't it?

Reference Article:
Rugg C, Kadoor A, Feeley B, Pandya N.  The effects of playing multiple high school sports on national basketball association players’ propensity for injury and athletic performance. Am J Sport Med.  Published online before print. 2018.
Purpose:
The purpose of this study was to determine if National Basketball Association (NBA) players who play multiple sports as adolescence are less likely to get injured.  In addition, do these multisport athletes have higher participation rates in terms of games played and career length over their single sport athlete counterparts.

Methods:
First round draft picks from 2008-2015 in the NBA were included in this study.  From publically available records from the internet, the following data for each athlete was obtained:

  • Participation in high school sports
  • Major injuries sustained in the NBA
  • Percentage of games played in the NBA
  • Whether the athlete was sill active in the NBA

Athletes who participated in sports in addition to basketball during high school were defined as mulitsport athletes and were compared with athletes who participated only in basketball in high school.  Breakdown of the multisport and single sport athlete data is represented below.



Results:
237 NBA athletes were included in this study of which 36 (15%) were multisport athletes and 201 (85%) were single sport athletes in high school.  The multisport cohort played in statistically significantly greater percentage of total games (78.4% vs. 72.8%) with a p value of .001 (remember p <.05 is statically significant).  Multisport athletes were less likely to sustain a major injury during their career (25% vs. 43%) with a p value of .03.  A greater percentage of multisport athletes were active in the league at the time of the data collection, indicating increased longevity in the NBA (94% vs. 81%) with a p value of .03.

What does this mean?  Simply stated that this appears to show that multisport athletes played more games per season, had longer NBA careers and were injured less.  Although this is a good sample size and over 7 year period, the number of multisport athletes is still relatively low.  Was this 15% purely representative of those freakish athletes that were just super talented and could play any sport no matter what?  That is hard to say.  Or is it that as a result of them playing multiple sports they are freakish athletes?  More likely, it is a combination of the two.

One thing we do know for sure is that multisport athletes due get injured less than single sport athletes.  We also know that by playing multiple sports, the training effect is much greater.  Those athletes who play multiple sports have a better kinesthetic awareness, better neuromuscular control, better agility and overall better athleticism.  Just like cross training, better prepares you physically rather than just doing one form of training, so does playing multiple sports.  That is why you see so many athletes today adding cross training to their routines.  In the off season, they are not playing their main sport, but rather biking, lifting weights, swimming.  We know this adds to recovery and helps to strength areas of weakness that may not be addressed during normal seasonal performnce of our sport.  Anecdotally, we have seen this in the clinic and now we are starting to see this represented in the research.  Just because we do not have a plethora of studies showing us this, it does make sense both from a physiological, neurological and psychological perspective.

So, the next time you have an athlete or parent thinking about playing a single sport, keep this in mind.  Single sport athletes get injured more and may not perform as good as multisport athletes.

Help us ring in 2020 sports season right by spreading the word and helping to prevent athletic injuries. #ViPerformAMI #ACLPlayItSafe #ResearchThatWorks


Dr. Nessler is a practicing physical therapist with over 20 years sports medicine clinical experience and a nationally recognized expert in the area of athletic movement assessment.  He is the developer of a 3D athletic biomechanical analysis, ACL Play It Safe and Run Safe programs, is an author of a college textbook on this subject  and has personally performed >5000 athletic movement assessments.  He is president of Vitality (a Divsion of Rebound), involved in several national research projects in the area of movement assessment and serves as a consultant to teams and organizations in the area of athletic movement assessment and RTSport testing.   He is also a competitive purple belt in Brazilian Jiu Jitsu and team physical therapist for several competitive teams. 

Monday, July 13, 2020

Does Sport Specialization Increase Risk for Injury?

Sports has a lot of positive impacts on kids.  Studies show that kids that participate in sports have an improved quality of life, are less likely to smoke, to be truant and more likely to get better grades and stay in school.  Under the right coach and with the right team, this can also provide a lot of positive influences to kids in a time and age where they really need this.  With over 7.8 million kids participating in interscholastic sports each year, sports injuries are  going to happen.  Our goal is always to minimize those that we can.

Obviously with the focus of our discussions through the history of this blog, we tend to focus a lot on lower extremity injuries and specifically knee injuries.  Why is that?  Ingram et al AM J Sport Med 2008 showed that the most commonly reported athletic injury between the ages of 15 and 25 is an injury to the knee.  Further, Fernandez et al Acad Emerg Med 2007 showed that lower extremity injuries accont for 60-75% of all injuries in high school athlete populations.  Rechel et al J Trauma 2011 showed that 50-60% of all athletic injuries requiring surgery where injuries to the knee.  If you include the low back injuries in these numbers, then you encompass >75% of athletic injuries that occur and hence why our focus primarily on the lower kinetic chain.

Over the course of the last several years, we have discussed various strategies on how we can help reduce these injury rates, especially in our younger athletes.  I have been blessed throughout my career to work along side some of the industries best in the field of sports medicine.  As such, it has led to some amazing learning opportunities.  Two of the pioneers in this area,  from an educational perspective, innovation perspective and research perspective, is Kevin Wilk, DPT, FAPTA (with Champion Sports Medicine - Alabama) and Dr. James Andrews (Andrews Institute - Florida).  Both of these sports medicine legends have and continue to be a huge influence on who I am professionally and what we do.  Dr. Andrews is the founding member of the American Orthopaedic Society for Sports Medicine's STOP Campaign.  STOP (link on the right hand of this blog) stands for Sports Trauma and Overuse Prevention and is a national campaign to help educate and prevent youth sports injuries.

According to Dr. James Andrews, the nation's leading expert in sports related injuries, one of the leading causes of preventable sports related injuries is early sports specialization.  Why is that?  It use to be when I played sports, it was a seasonal thing.  You played your sport during the spring or fall and then when the season was over you either played another sport or you did something else.  Today however, sports are all year round.  Where a soccer player may start their season with the school, then once that is over, the athlete then move on to play with their club or travel team resulting in the athlete sometimes playing the same sport all year long.  Parents unknowingly think this will help them become a better athlete.  Give them a competitive edge.  Yet the reality is, they are also increasing their risk for injury.  Is this true?  What does the research tell us?

Reference Article
McGuine T, Post E, Hetzel S, Brooks A, Trigsted S, Bell D.  A prospective study on the effect of sport specialization on lower extremity injury rates in high school athletes.  Am J Sports Med. 45:2706-2712. 2017.

In this prospective study, the authors set out to determine if sport specialization was associated with increase risk for lower extremity injuries in high school athletes.

Methods:  Participants in this study where interscholastic athletes in grades 9 through 12th.  Athletes were recruited from 29 Wisconsin high schools during the 2015-2016 school year.  Participants completed a questionnaire identifying their sport and history of lower extremity injuries.  Sports specialization of low, moderate or high was determined using a previously published 3-point sale.  Athletic trainers reported all lower extremity injuries that occurred during the school year.  Statistical analysis was performed on the data.

Results: A total of 1544 athletes participated in the study, 780 females and 764 males.  A break down of the subject by sport is in the table below.  Mean age was 16.1 y/o +/- 1.1 years.  These athletes completed 2843 athletic seasons and participated in 167,349 athletic exposures.


235 participants (15.2%) sustained a total of 276 lower extremity injuries that caused them to miss a median of 7.0 days.  Injuries occurred most often to the ankle (34.4%), knee (25%) and upper leg (12.7%).  Injuries included ligament sprains (40.9%), muscle/tendon strains (25.4%) and tendinitis/tenosynovitis (19.6%).  Statistical significance is determined by a P value <.05.  The incidence for lower extremity injury for those that had moderate sport specialization was p = .03 and for those that had high sport specialization was p = .02.

What this indicates is that the more the athlete specializes in a single sport versus multiple sports, the higher the likelihood for them to suffer a lower extremity injury.  Next week we will look at one additional study and why sport specialization may be leading to an increase in risk.

Help us ring in 2018 right by spreading the word and helping to prevent athletic injuries. #ViPerformAMI #ACLPlayItSafe #ResearchThatWorks


Dr. Nessler is a practicing physical therapist with over 20 years sports medicine clinical experience and a nationally recognized expert in the area of athletic movement assessment.  He is the developer of a 3D athletic biomechanical analysis, ACL Play It Safe and Run Safe programs, is an author of a college textbook on this subject  and has personally performed >5000 athletic movement assessments.  He is president of Vitality (a Divsion of Rebound), involved in several national research projects in the area of movement assessment and serves as a consultant to teams and organizations in the area of athletic movement assessment and RTSport testing.   He is also a competitive purple belt in Brazilian Jiu Jitsu and team physical therapist for several competitive teams. 

Monday, July 6, 2020

Neuroplasticity and ACLR Rehab - Part V

Last week we talked about some specific training strategies we could used based on the most current research.  Strategies that will work on external focus (result of the movement) versus internal focus (focus on the movement itself).  We gave two specific examples of exercises that will work on external focus and which will create neuroplasticity in the higher centers and reduce risk of reinjury with return to sport. 

Working with multiple centers around the US and attempting to create consistency in the way that this training is applied can sometimes be difficult which results in a significant variance in outcomes from center to center, state to state and nationally.  As such,  we have recently identified a technology that allows us to create more consistency.  By using this technology, we can implement this type of training, standardize how it is implemented and through the use of specific protocols, create much more consistency in the results we get regardless of the clinician.   

Quick Board, LLC is a company that developed a sensor board that will Bluetooth to an Ipad.  The Ipad has the Quick Board app that communicates to the sensor board.  This large sensor board has five circles on it, spaced apart all of which contain sensors underneath.    The app has a diagram that is positioned and looks identical to the sensor board.  For each test, the athlete watches a standardized video instruction which shows the athlete what the test is and exactly how it is performed. 

After watching the video, the athlete is instructed to keep their eyes on the Ipad.  The Ipad will highlight one of the targeted circles that the athlete is to touch.  Without looking, the athlete is to reach and touch the corresponding circle.  As soon as the athlete touches the circle, the sensor is activated.  This will record not only the time it takes to touch the circle (from time appeared on the app to actual touch) but also the accuracy (did they touch the right circle).  From this, there are a lot of things that can be measured including:

  • Average reaction time for each sensor location for:
    • Single color exercises 
    • Discrimination tasks - only touch blue versus red (or another color)
    • Go or no go tasks - measuring error rate and reaction time with
  • Average contact time for each sensor location - how long the foot is on the sensor 
  • Accuracy - measure of correct touches versus errors
  • Vertical jump (based on fight time and body weight)
    • Jump height 
    • Reactive strength 
Limb symmetry index (LSI) can also be measured in all of these measures.  This way you can see the variance in the operative and non-operative time as they progress through the rehab process.  This was developed by a strength and conditioning coach and found a lot of success in using this in performance training. Athletes that would improve their performance on these measures were also improving their sprint speed and power.  Based on these results, there has been a large adoption of this technology in professional sports from basketball to football.  


However, this also has huge applications in lower kinetic chain rehabilitation.  I use this with all my lower kinetic chain rehab but specifically with my ACLs.  In addition to seeing the changes that occur in sprint speed and vertical jump, we are also seeing huge improvements in:

  • Performance on TSK-11 - improved scores indicating decreased fear of reinjury
  • Improve performance on the ViPerform AMI.  Specific areas of improvement:
    • Improved control of frontal plane motion (degree of motion and speed) on:
      • Single leg squat
      • Single leg hop
      • Single leg hop plant
    • Improved LSI across all measures 
    • Improved scores on full return to sport testing at 9 and 12 months 

I have no financial tie to this product nor incentive to say this other than it works.  If you are looking for something to address neuroplasticity training and incorporate with your ACLR rehab, then this is an ideal tool.  We are currently conducting several studies looking at the impact of implementing this training device with our ACLR athletes.  Based on the things we know that matter and that we measure, how is this training impacting those results? 

By using this technology, we are seeing a direct impact on the biomechanics that we measure with our wearable sensor technology (ViPerform AMI) and on the TSK-11 numbers we see in our athletes.  We know when these numbers improve on our assessment and the TSK-11 that risk of reinjury with return to sport goes down.  We know by improving LSI that risk goes down and athletic performance goes up.  We know improvement on our return to sport assessment (ViPerform AMI and 3D Sprint Assessment) equates to decreased risk of reinjury and improved athletic performance.  We also know that we can create more consistency in the way that this type of training is implemented from site to site regardless of the clinician (as long as they follow the simple instructions...). 


Whether you choose to implement this device or not, addressing neuroplasticity is and should be a critical part of your rehab, especially with ACLR.  We now know there are changes that occur in the higher centers that DO NOT self correct and we MUST do targeted interventions to address.  If we don't do that, we are returning our athlete to the field and competition with a heightened level of risk. 

I hope you found this a valuable series.  As always, I appreciate all our followers and hope you find the information we provide useful in your practice with your athletes.  If you do, please follow me on instragram @bjjpt_acl_guy and Twitter @acl_prevention.  I also just launched a new website, www.drtrentnessler.com.  My vision is to create a movement revolution in the world of ACL rehab.  Check it out, hear more about my story and where we are headed.  Train hard and stay well.  #ViPerformAMI #ACLPlayItSafe


Dr. Nessler is a practicing physical therapist with over 20 years sports medicine clinical experience and a nationally recognized expert in the area of athletic movement assessment and ACL injury prevention.  He is the founder | developer of the ViPerform AMI,  ViPerform AMI RTPlay, the ACL Play It Safe Program, Run Safe Program and author of a college textbook on this subject.  Trent has performed >5000 athletic movement assessments in the US and abroad.  He serves as the National Director of Sports Medicine Innovation for Select Medical and movement consultant for numerous colleges and professional teams.  Trent also a Brazilian Jiu Jitsu purple belt and complete BJJ/MMA junkie. 

Monday, June 29, 2020

Neuroplasticity and ACLR Rehabilitation - Part IV

Last week, we started our discussion talking about explicit strategies (internal focus on the movement itself) and implicit strategies (external focus on the movement effect).  These are types of training or verbal instructions we give to patients during performance of rehabilitation exercises.  What the studies show is that implicit strategies have a better carry over to sport and create greater neuroplastic changes in the higher centers (specifically the motor cortex, somatosensory area and cerebellum).  These types of changes reduces risk for reinjury with return to play as these are the patterns the athlete resorts to during functional activity. 

In our last discussion, we talked about the difference between these two strategies and when using one form of training or instruction may be indicated versus another form.  We also discussed how your verbal instructions can significantly alter movement and I gave the specific example of how this can alter the movement when performing a functional movement assessment. 

When looking at how this might impact our training, we can look at the study by Benjaminse et al Phys Ther Sport 2015.  In this systematic review, the authors looked a different forms of training.  For this example, we will use the ACLR specifically and doing single limb training.  Based on the data we have collected on over 18,000 athletes with the ViPerform AMI, we know control of both the magnitude of frontal plane motion and speed of valgus during single limb performance is critical.  If athletes can control this during training and functional activities (sports) then we know we have impact or mitigate some of the risk with them returning to play.  Based on the neuroplasticity research, there are some innovative ways do accomplish this.

Using a single leg balance on an unstable surface as an example.  In this exercise, I want the athlete to control the magnitude of frontal plane motion and speed of that motion.  In exercise A, I am placing a mirror in front of the athlete and asking them to control their knee,  Don't let the knee go in toward midline.  In this instance, I am using an internal focus, focusing on the movement.  In exercise B, I give the athlete a PVC pipe and ask them to keep the bar horizontal.  In this example, I am using external focus, focusing on the result of the movement. 


What we see here is the result.  In exercise A, although the athlete is successful at controlling her frontal plane motion, she also has a lot of hip motion occurring.  At the same time, what we find (or according to the research) is that this does not carry over as much to her actual movement in sport.  In exercise B, we see that not only is she maintaining better alignment at the knee but her hip position is also much better.  Considering this may have better carry over to sport, then this might be a strategy that I employ.  At the same time, I can add additional stresses to the system to make her maintain that positioning and posturing while specifically targeting her areas of weakness.  If you go back to our blog where we talked about rapid neuromuscular response (RNMR) training, you can see some specific exercises targeting that. 

In the next example, using a single leg squat.  In exercise A, I am placing a mirror in front of the patient and asking them to perform a single leg squat and asking them to keep their knee over their toe and not allow their knee to go in towards midline.  This is again a form of internal focus where I am focusing on the movement.  In exercise B, I am placing a cone in front of the athlete and asking them to reach toward the cone with their knee.  This is a form or external focus or a focus on the result of the movement. 


Again, what you see in exercise A is that the athlete, although better, still has some increase in frontal plane motion at the knee and has a lot more motion at the hips.  In exercise B, we not only have better control of frontal plane motion but also much better positioning and posturing of the entire kinetic chain and core. 

Again, these are two examples but you can see how internal focus versus external focus can be applied with our training.  That said, I want to be clear.  Although the research does say that external focus does have a better carry over to sport and functional activity, as with all training, I believe there the need to use both forms of training.  Similar to OKC and CKC exercise.  Research supports use of CKC exercise but I strongly believe that both OKC and CKC exercise have a place in rehabilitation and performance training.  To focus on just one, I think you miss part of the picture.

I hope you found this valuable and next week, we will continue this discussion.  Specifically, next week I will talk about a device we are using in our ACLR rehab that addresses all this as well as some of the results we are seeing with.  As always, I appreciate all our followers and hope you find this useful in your practice.  If you do, please follow me on instragram @bjjpt_acl_guy and Twitter @acl_prevention.  I also just launched a new website, www.drtrentnessler.com.  My vision is to create a movement revolution in the world of ACL rehab.  Check it out, hear more about my story and where we are headed.  Train hard and stay well.  #ViPerformAMI #ACLPlayItSafe


Dr. Nessler is a practicing physical therapist with over 20 years sports medicine clinical experience and a nationally recognized expert in the area of athletic movement assessment and ACL injury prevention.  He is the founder | developer of the ViPerform AMI,  ViPerform AMI RTPlay, the ACL Play It Safe Program, Run Safe Program and author of a college textbook on this subject.  Trent has performed >5000 athletic movement assessments in the US and abroad.  He serves as the National Director of Sports Medicine Innovation for Select Medical, is Vice Chairman of Medical Services for USA Obstacle Racing and movement consultant for numerous colleges and professional teams.  Trent also a Brazilian Jiu Jitsu purple belt and complete BJJ/MMA junkie.