Off The Road Column - The 6 Boxes

by Russ Ebbets, DC


When I taught in USATF’s Coaching Education Clinic one of my topics was biomechanics. Of all the 23 hours of the weekend clinic the most dreaded unit, by most of the coaches, was biomechanics. For most the subject matter was an unfamiliar mix of math, physics and anatomy that a rudimentary background rendered mysterious, confusing and intimidating.

This made my task of getting the salient points across all the more daunting. Initially I detailed why biomechanics was important and briefly listed the broad application of the science to the sport. I then told the coaches the subject matter would be broken down into linear and rotary concepts. Everybody got that. Everyone could identify events that were “straight-line” and the events that used some type of a spin. Then I told them that 21 concepts would be covered, and they would be numbered. If anyone was still anxious, they could do the math, actually subtraction, and see that while the end might not be literally “near” it was getting nearer.

After wading through such concepts as velocity, rotary momentum, hinge moments and various types of muscle contractions I’d finish up by stating that the human body could only move in six different ways, represented by the six boxes (Figure 1). Initially I am sure this confused many, or at least, raised some doubts. How could that be? Forty-five minutes earlier, everything was a mystery, a great unknown and now it can all be reduced to six movements? But given a moment’s pause the class could start to see that limb movements, joints actions, muscular contractions, trunk actions all mimic, to some degree, the actions represented by the six boxes. In the end the six boxes neatly summarized the general concepts (linear and rotary motions) I used to introduce the session. More importantly this strategy left the coaches with a new appreciation for the import of biomechanics and underscored the application of biomechanics to the various techniques of running, jumping and throwing that make up the sport.

Figure 1. The 6 Boxes

Box A is not a movement. It represents a position of relaxed attention. One can think of it as standing up straight. From this position all the other boxes can get their start, and at some point, return to after completion of their action.

Box B represents compression. Gravity creates compression in the body and represents the lifelong battle we wage against this unseen force. Gravity constantly brings us back to earth and limits the explosive efforts produced by muscle contractions that move the various lever systems within the body to create movement. Much of the training for running, jumping or throwing is to overcome the resistance gravity presents.

Distraction is represented in Box C. Honestly, distraction has more of a therapeutic application to sport with the “pulling apart” of different joint complexes that were jammed together by compressions of Box B. Nonetheless, the unseen, but ever present, activation of the stretch reflex (aka – the stretch-shortening-cycle) is an example of how the initial traction or distraction of a muscle can subsequently produce a more powerful contraction, essentially offering “free energy” to a well-timed and well-coordinated action that will aid performance.

A second application of distraction are the eccentric or lengthening contractions that take place as a joint complex opens up with routine movements. Eccentric muscular contractions, for most, are minimally trained, poorly coordinated and where most muscle injuries take place.

Box D represents the bending that takes place in the body. This is a combination force in that one side exhibits compression and the other side distraction. The continual flexion or extension of joints is an obvious application of these movements, but this box can also represent sideways bending, a leaning to the left or right, that compresses one side and distracts the other.

Box E represents shearing or gliding that takes place in a joint complex when parallel forces are applied in opposite directions. In truth, this is not a voluntary action in that one cannot consciously create motion. The actions of flexion and extension also include some gliding at a joint, however slight that might be. The knee (tibio-femoral joint) is the preeminent example. Some gliding ensures the knee’s lubricating synovial fluid will be spread around. Too much gliding can sprain the adjacent capsule, ligaments or tendons and directly contribute to any instabilities found at the knee.

Finally, there is counter rotation or torque represented by Box F. This is where rotary motions, moving in opposite directions help create a rotary stretch reflex with the tissues involved to give the power positions (positions of greatest strength production) of the throws their extra snap. For the runner the internal/external rotation of the tibia with the heel strike/midstance and toe off allow for the foot to smoothly transition from being a rigid lever to a mobile adapter and back to a rigid lever for forward propulsion. Interestingly, the cross crawl pattern developed in infancy helps develop into the walking cross crawl pattern adults use to balance the body with upright walking.

What does all this mean? It might impress your running partners to have an understanding of joint biomechanics but how does all this fit into one’s personal improvement plan? Very simply, it underscores the importance of technique. The jumps, throws and hurdles are heavily dominated by “techniques.”  These techniques are a series of prescriptive movement patterns that dictate actions and in some instances are legislated by the rules of competition.

In the 1920s biomechanics was a dirty word. The problem was that the comparison of the human body to the soulless, mechanical movements of a machine was thought to be dehumanizing. If you have ever seen the movie Chariots of Fire, the British sprinter Abrahams was coached by the Italian Morabito. Although crude by today’s standards Morabito applied biomechanical principles in Abrahms’s training to help him win the gold medal.

 For a runner an understanding of movement patterns represented by the six boxes may be seen as a trivial or unnecessary detail but one’s understanding and ability to apply this knowledge underscores the importance of running technique.  Foot placement, knee lift, body lean, symmetry of arm movements and head carriage all can dictate or promote efficiency of movement (running economy), force development, ground contact times, energy expenditure, forward velocity, injury prevention or career longevity. An awareness and application of the knowledge will direct training choices and provide exercise options that can combine to create improvements in both the near and distant future.

One of the great challenges of biomechanics is that it is a subject that has many, many different concepts that represent many unrelated ideas. That makes the usefulness of learning of one not necessarily relatable to the learning of another. But with time, effort and energy this can be done. After all, the alphabet I write, you read, was once upon a time an absolute mystery to us all. The 26 moving parts that represent various sounds, images and ultimately combine to form concepts, thoughts and ideas was once a mystery to us all.

Einstein is credited with saying – if you can’t explain something simply, you don’t understand it well enough. A recognition and understanding of the body’s movements, the biomechanics represented by the six boxes gives one a deeper appreciation and understanding of the technical aspects of a run, jump or throw, that allows one to more carefully and concisely design a training regimen that maximizes or at least optimizes the body’s abilities based on the laws of math, physics and biomechanics. The learning here is a step-by-step process. But we all have a successful history of this, just like the alphabet we learned long ago, we traded crawling for a walking gait that began one step at a time.  

RussEbbets20.jpgRuss Ebbets, DC is a USATF Level 3 Coach and lectures nationally on sport and health related topics. He serves as editor of Track Coach, the technical journal for USATF. He is author of the novel Supernova on the famed running program at Villanova University and the sequel Time and Chance. His 2019 book, A Runner’s Guide, a collection of training tips and running articles was a 2019 Track and Field Writers of America Book of the Year finalist. A Runner’s Guide 2 was published in February 2023. Books are available from He can be contacted at

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