Monday, October 8, 2018

How Does Human Movement Occur - Kinetic Chain in Action

I went broke believing that the simple should be hard.
Matt Nathanson

In order to develop strategies which will improve movement, and eliminate pathokinematics in our athletes and others we work with, we must first understand how human movement occurs in the first place.  Our understanding of the human body and the systems that make it work, as vast as it is, is still so limited when it comes to its full and integral complexities.  For our purposes and the purposes of this blog, we mostly focus on the musculoskeletal system (skeletal system, muscles, cartilage, ligaments, tendons and joints), the nervous system (neuromuscular system - sensory and motor nerves and central nervous system – higher centers and spinal cord) and the cardiovascular system (heart, lungs, veins and arteries), and how they work together so that the body can move.   

However, the human body is an extraordinarily complex interaction of these and many other systems that influence its action, health and wellness.  The human body relies on the “optimal performance” of all of these systems in order to provide optimal performance in life and in sports.  If there is a break in any of the systems or “links in the chain,” then optimal performance cannot be obtained, and over time, damage can occur. 

The Kinetic Chain

Human movement occurs thanks to the “kinetic chain.”  Kinetic means force, and chain is defined as a system that is linked together.  Throughout this book, when we refer to the kinetic chain, we are referring to the system of interconnected body segments that allows the body to move.  For our purposes, the kinetic chain includes the parts of the body which directly or indirectly impact the positioning, alignment, strength, endurance and performance of proximal or distal segments of the body.  The nervous system, the musculoskeletal system, as well as the cardiovascular system, all work together to transfer energy or force through the body to the extremities in order to cause movement.  The majority of this text is focused on the lower kinetic chain, which for our purposes refers to all of the muscles, bones, ligaments, tendons, joints and all associated neurological input systems that influence those structures from the chest (pectoral muscles) to the feet. 

A kinetic chain can be open or closed.  A closed kinetic chain is one in which the hand or foot, or other moving body part, is in a fixed position during movement.  In this type of movement, because one or more extremity is stationary, resistance from the stationary surface is felt throughout the entire body, including and especially in the trunk, and specifically in the core.  In closed kinetic chain situations, when movement occurs all of the connected segments of the body are involved simultaneously.  An open kinetic chain is one in which the extremity or extremities are not fixed to any stationary surface and are therefore simply free in space.  In an open kinetic chain only the part of the body that is free in space and those parts closest to it are directly involved in the movement.

Therefore, in a closed kinetic chain, the parts of the system act in dynamic unison and in an open kinetic chain, they act more in isolated segments.  Most sports and functional life activities are closed kinetic chain activities, since in most cases the body or one of its extremities is fixed against a stationary object or surface (the ground, a chair, etc.) and all parts of the body work together dynamically.  Consequently, closed kinetic chain exercises require and reinforce recruitment patterns of the neurological, muscular and skeletal systems in ways that most closely mimic those used in sports and the activities of daily life.  They are the most effective for improving movement, preventing injury and enhancing sports performance, since they are more like sporting and “real life activities.”  Examples of exercises that are closed kinetic chain are squats and push-ups.  In comparison, leg extensions and triceps push-downs are examples of open kinetic chain exercises. 

How can we see the kinetic chain in action so that we can ultimately understand how movement occurs?  One way is to look the arrangement of the parts of the body by looking closely at the musculoskeletal system.  When we refer to the musculoskeletal system, we are referring primarily to the skeletal system, (bones), and the muscles, ligaments, tendons, other connective tissue and joints that hold the skeletal system in place.  We can see this system at work both when the body is still (statically) and when the body is in motion (dynamically).  Let’s begin by looking at the posture of an individual in a standing and stationary position.

As basic as it sounds, to truly change movement, we must change the way that we think.  And although it is not 100% data driven, it is 150% science driven.  Over the course of the next month, I blogs to help us all understand better the sciences behind movement and why we should do what we should do.  And that is, assess it better.  Move better, feel better, perform better and last longer.  That simple!   

Next week, we will start to dissect this a little more.  If you are enjoying our blog, please share it and follow us on twitter @ACL_prevention and on Instagram at @Bjjpt_acl_guy 


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, 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 is also a competitive athlete in Brazilian Jiu Jitsu.