Posts Tagged ‘human performance’


Injuries to the knee are seen throughout virtually all sports and all age ranges. Have you ever wondered why the knee is the most common reason for a visit to an orthopedic surgeon? Moreover, have you ever wondered how rehabilitation and training programs could better alleviate the stresses placed on the knee? The answers lie in using Applied Functional Science to understand the chain reaction biomechanics of the two “bookend” joints of the knee – the hip and the ankle.

Although the distal femur and the proximal tibia form the primary knee joint, the other ends of these two longest bones in the body reveal the reactive nature of the knee. The knee is referred to as a reactor because it responds to drivers from above and below. These drivers can be ground reaction force, gravity, momentum, hands, feet, or often times the eyes. During initial foot contact in upright function, the ankle joint, comprised of the distal tibia and talus, create a chain reaction from the ground up that directly influences the knee via tibial and fibular motion. Similarly, the hip joint, comprised of the proximal femur and the illium, influences the knee from the top down via the femur. The three-dimensional motions of these two “bookend” joints play a significant role in determining the magnitude of stress placed on the knee. An appropriate chain reaction from these two bookend joints enables the knee to effectively dissipate significant forces. However, dysfunction at either joint can leave the knee caught in the middle with few places to go and nowhere to hide.


A practical example of the chain reaction relationship between the ankle and the knee can be illustrated using a female beach volleyball player. Based on its attachment sites, the ACL it is placed under stress during combined knee flexion, abduction (i.e. valgus), and internal rotation. In this example, as the volleyball player approaches the net and begins to load her lower extremity to prepare for jumping, she steps in an uneven sand hole which causes her heel to abruptly evert and her talus to plantarflex and adduct. This motion of the talus influences the tibia to internally rotate and abduct. This tibial motion, if not properly decelerated, will create excessive knee internal rotation, abduction, and flexion which can directly lead to a right ACL tear. However, this motion can be properly controlled and reduce the risk of injury by muscles properly decelerating the tibia and femur. The specific tri-plane action of muscles that influence the knee are too numerous to adequately describe in this article and, therefore, will be discussed in an upcoming newsletter.

A second practical example can illustrate a situation when dysfunction at the hip is the underlying cause of patella femoral pain. Recent research has confirmed Gary Gray’s long held belief that patella femoral pain is more a track problem (femur) than a train problem (patella). Dr. Chris Powers, et al, summarized that “patellofemoral joint kinematics during weight-bearing conditions could be characterized as the femur rotating underneath the patella.”1 In another study, Dr. Powers, et al, goes on to assert that “interventions aimed at controlling hip and ankle motions may be warranted and should be considered when treating persons with patellofemoral joint dysfunction.”2


A forty-year-old triathlete with excessive femoral internal rotation during the loading phase of gait presents lateral right knee pain while running. His knee pain can be explained by the inability of the hip external rotators, adductors, and hamstring muscles to decelerate the excessive femoral motion. The track crashing toward midline too rapidly, in effect, causes the train to derail laterally. The symptoms are present at the knee; however, through use of lower extremity chain reaction biomechanics, one can easily understand how the cause is at the hip.

These examples illustrate a few core principles of Applied Functional Science. First, joints in the body move in three planes of motion. Second, function is driven by, among other things, ground reaction force, the environment, and gravity. Third, movement at one joint will create chain reaction responses at other joints throughout the body. Lastly, function is individualized and task-specific.

Applied Functional Science requires us to understand the person, tasks, and goal(s). A thorough understanding of the chain reaction biomechanics of all three joints will assist in implementing rehabilitation and training programs that ensure that, although still caught in the middle, the knee now has two powerful friends by its side. ——-By Brett Bloom

Gray G: Functional Video Digest. Functional Manual Reaction. The Knee. v3.7

Gray G: Functional Video Digest. Patella Femoral. The Train & The Track. v2.5

1. Powers CM, Ward SR, Fredericson M, Guillet M, Shellock FG. Patellofemoral kinematics during weightbearing and non-weightbearing knee extension in persons with patellar subluxation: A preliminary study. J Orthop Sports Phys Ther. 33:677-685, 2003.

2. Powers CM. The influence of altered lower extremity kinematics on patellofemoral joint dysfunction: A theoretical perspective J Orthop Sports Phys Ther. 33:639-646, 2003

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Examining the characteristics of the human body further assists in understanding function.  This allows for better understanding of human movement for improved program design and rehabilitation programs.  For e a more depth explanation and further discussion check out my freind and colleague JC Santana’s book Functional Training; Breaking the Bonds of Traditionalism.

 The proportions of the human body are distinct from one person to another.  Therefore we all have unique movement patterns that are consistent with our strength, weaknesses and utility.

Our bodies are made to fit us.  They are a product of what “function” we have dictated for it.  That is why athletes look like athletes and couch potatoes look as they do.

The next two concepts probably have the most significance to training.

Our bodies have the ability to adapt.  This was first discovered by a Canadian endocronologist (Hans Seyle).  He was looking at the adrenal response of rats and stress.  He developed the General Adaptation Syndrome (GAS)  We have the ability to adapt both neurologically and morphologically.  Neurologic adaptations are what allow us to gain strength minute to minute.  Its due to synchronization, rate coding and proprioception.  Whereas morphologic changes are actual increases in the actual size of the muscle (hypertrophy).  This can take 6-12 weeks.

Lastly, proprioception is the communication system for reaction and interpretation of input from the body and its surroundings.   The body/brain uses all the proprioceptive info to make a decision on how and when to perform a specific movement or task.  Remember that muscles are dumb, they rely on proprioceptive and mechanorecptor info.  Proprioceptors are also a safety mechanism to inhibit harmful forces.  I think of proprioception as the foundation to human movement.  The muscles are slaves to the brain.  Power is nothing without control.  Most people are only concerned with strength without a thought to training balance.  I like to use the analogy that i would not put them in a formula 1 race car without brakes or a steering wheel.  Brute strength in function and sport is not as important as rate of force development.  Can you utilize the strength you have at have right time in the right amount to successfully complete the task or skill?  If you cant, your 300 pound bench press or 500 lb squat is meaningless (in function/sport).

So, based on the characteristics of the human body it becomes more clear the need to train the body functionally using more life/sport specific types of exercises.  Train the body for the task it is intended for using movements and positions that closely resemble the task to react /respond to gravity, ground reaction forces and momentum.

PS…unless your goal is body building.  In that case the body building approach is still the best way.

The question to ask yourself is are you training for “show” or “go”??

Get Strong! Stay Strong!  (But do it functionally!)


When you think of human movement it can be broken down into 4 basic categories.  Locomotion, Level Changes, Push/Pull and Rotation. These represent the 4 pillars of human movement as described by JC Santana in his book Functional Training; Breaking the Bonds of Traditionalism.  When designing rehab or fitness programs that are functionally based it is important to make sure all 4 pillars are incorporated.

LOCOMOTION:  This is the foundation for ground based force production.  It is the linear displacement of our bodies center of mass.  It is a triplane event in which all the muscles and joints are moving simultaneously in all three planes.  While at first glance it appears the body (while walking) is moving primarily in the sagittal plane(SP) (forward) close look would reveal that it is the transverse(TP) and frontal plane(FP) movement that drives us in the sagittal plane.  The TP and FP movement become more apparent when running.  This also requires the ability to efficiently load into the ground (deceleration) followed by the unloading or propulsive phase (acceleration).

LEVEL CHANGES:  This represents non locomotor tasks such as getting up off floor, picking up the baby or taking someone to the ground.

PUSHIN/PULLING: We use various push and pull movements for many everyday activities.  Opening and closing doors, pushing the stroller, taking a hanger off the rack and punching.  Pushing and pulling usually done unilaterally in a reciprocal manner is cross wired neurologically.  As one punch is thrown the opp. arm is retracted to eccentrically load in order to prepare for the next punch.  The same is true for arm swing in walking.

ROTATION:  Responsible for changes in direction and rotational torque production.  Dancing, throwing, and  running are examples of activity with a significant amount of rotation.  The transverse plane is probably the most important and the only plane not loaded by gravity.  The example I like to use to demonstrate the point is that a bicycle only moves forward because the wheels are rotating.  Approx. 90% of all the muscles are oriented in the diagonal to enhance rotational deceleration and acceleration.

Obviuosly many tasks consist of combinations if not all the above categories, but each has a unique and important contribution to human movement.  So, whether you are rehabbing or training it is important to include movements from each of the 4 pillars.

Get Strong! Stay Strong!