The Evolving Knowledge of Movement - Part VII What We Know Now

Last week, we talked about the impact concussion has on movement and how this can influence some corrective techniques we can do to influence these movements.  This week we want to get into looking at control of frontal plane motion.

As clinicians, when we see athletes presenting like this, we think of all the musculoskeletal injuries that could happen as a result of the way that this athlete is moving.  However, as a strength or performance coach, we might see an athlete who's vertical jump or explosive power is going to be impacted.  The reality is that both answers are right.  In jumping sports, the lower extremity has to attenuate anywhere from 4-8 times body weight (Nordin et al Basic Biomechanics of the Musculoskeletal System - 4th Edition).  If one of the joints is not moving optimally (example here moving into excessive valgus) then there are structures that are stressed at that joint and the joints distal and proximal to.  This can add to a plethora of non-contact musculoskeletal injuries.

At the same time, these same movement patterns lead to a loss of kinetic energy across the system which lends to a loss of explosive power.  After assessing 1000s of athletes, some of the things we have seen is that explosive power is impacted by:

• Magnitude of frontal plane motion - the greater the increase in frontal plane motion, the greater the impact on explosive power.  As the magnitude of frontal plane motion is improved, there is an equivalent improvement in explosive power.
• Speed of frontal plane motion - the greater the speed of frontal plane motion, the greater the impact on explosive power.  If there is a decrease in speed of frontal plane motion, irrespective of change in magnitude of motion, there is an equivalent improvement in explosive power.  

The sad thing about these findings is that a LOT of athletes train without controlling these factors.  They will focus more on the loads lifted or the volume of exercise and not necessarily the quality of the movement.  Although load and volume are critical, this should never be at the expense of controlling frontal plane motion.  From a simple motor learning perspective, if an athlete is allowed to train with with poor frontal plane control under heavier loads or with increased volume then what happens is this is the pattern they resort to under these kind of demands or in a fatigued state.  

As depicted here, control of this frontal plane motion can can mean the difference between simply lifting or obtaining a PR.  The best part of all is that once this is identified, you can change it through directed corrective exercises.   The first step is knowing how to assess it.  Studies show that identifying these movement patterns in bilateral tasks (squatting motion or bilateral box jump) is difficult to do (Krosshaug et al Am J Sport Med 2016).  Although these biomechanical flaws (decreased control of frontal plane motion) may not be easily assessed in bilateral activities, they can be easily assessed in single limb activities (King et al Am J Sport Med 2019).  That said, the movements that we see that are the most telling is the single leg squat and the single leg hop plant.  

• Single leg squat - the athlete stands on one leg, with the contralateral leg in a slight hip extension with knee flexion (the athletic position requires greater glut control and mimics running).  The athlete performs 10 single leg squat on each side without touching the contralateral limb to the floor at anytime during the test.  During the test, you are recording the number of reps where there is not frontal plane motion control vs. successful reps and the number of losses of balance (where they touch down the contralateral foot).  You can use that to determine symmetry between the right and left. 
• Single leg hop plant - the athlete stands on one leg, with the contralateral leg in a slight hip extension with knee flexion (the athletic position requires greater glut control and mimics running).  The athlete jumps in the following sequence: forward, backwards, lateral and medial.  This is repeated for 2 cycles on each side without touching the contralateral limb to the floor at anytime during the test.  During the test, you are recording the number of reps where there is not frontal plane motion control vs. successful reps and the number of losses of balance (where they touch down the contralateral foot).  You can use that to determine symmetry between the right and left.  

 *Use caution with the hop plant.  To do all directions and reps is a clinical decision based on how safe you feel the athlete is to perform the task.*  These movements are within the standard of practice and less stressful than what they will go through with sport but the medial hop tends to be very revealing to inability to control frontal plane motion.  Therefore caution should be used and close observation should be provided.

Once these tests are complete, you can then have a baseline measure of how the athlete is performing and this will give you something you can compare to after targeted training has been provided.  According to the research, you should give 6-8 weeks of training between testing in order to observe clinically meaningful improvements (Bodkin et al Am J Sport Med 2020).

Next week, we will continue this discussion as we look at on how we change these movements through movement guided interventions.  Stay tuned as I am super excited to share with you.  If you enjoy this blog, please share with your colleagues, athletes and training partners and please be sure to follow us on instagrm @ bjjpt_acl_guy and twitter @acl_prevention.  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.