As we begin to broaden our understanding of the complexities of the human body, we continue to be humbled by the power of its design and its capacity to teach us. When observing human motion, there are a number of undeniable truths.
For many years, we have studied human anatomy in an attempt to obtain a greater conceptual view of our segments in motion. These understandings have led our industry to choose exercises that focus exercises to certain segments of the body (i.e., a seated bicep curl) and create unnatural control and speed of movement. Take for example an exercise that typically occurs in the gym. An individual grasps two weights in either hand of an identical load, often sitting down with this load, and then he proceeds to exhaust a segment of the body. When this particular segment starts to exhaust, others areas of the body are willing and able to help, leading to less than "perfect" form for the exercise - this is the brilliance of the body! If compared to an everyday movement (say, lifting a bag of groceries), we all know that such a movement would elicit a full bodied approach where lever length becomes relative to the load and momentum would most certainly be used (especially if the weight is heavy enough). All human movements MUST rely on momentum. Think of throwing a ball, swinging a club, walking, running, etc... these movements use aspects of momentum that your body always takes advantage of. This is done for numerous reasons: to attenuate forces of a multitude of joints, conserve energy, take advantage of the elastic properties of our bodies, excite our nervous system, and maximize our neuromuscular efficiency. Think of how hard it would be if, while performing a bench press, you could NOT take advantage of the downward momentum of the bar coming to the chest before you pushed back up, or how hard it might be to perform a lay up in basketball WITHOUT the advantage of using running momentum to load into the ground?
What the Science is Telling Us
Momentum is defined as “the force with which a body moves, the product of its mass and its velocity; the impetus resulting from movement.” Clearly with this definition in mind, the more mass we move (either external or internal), the more it is accelerated (because of ever present gravity), and the more force (or momentum) we create - this is Newton’s 2nd Law of motion (F=ma). The question becomes, have we adequately prepared our bodies to deal with this momentum? The study of human biomechanics clearly delineates the fact that we are NOT simply different segments strung together, but rather, we exist in relationships between all of our segments to create a resultant goal: movement (see Figure 1 below).
In Figure 1, notice how the body structures work together to produce, in this case, forward (sagittal) movement. Note that the arms must produce momentum in the opposite direction as that of the legs. This not only cancels out any angular momentum, but it also causes the pelvis and ribs to rotate in opposite directions, up-regulating the nervous system (as I will discuss later) and creating a mechanical advantage for most of our muscles that attach obliquely (internal/external obliques, lats, glute max, adductors, VMO, just to name a few). Without using momentum in this particular movement, you would compromise not only safety but most certainly the function of the body as a whole. Try running without the use of momentum through your arms and shoulders and see how efficiency you are and/or how well you attenuate mechanical stress.
Simply put, our body is made up of only ONE structure with many parts. This design allows the human body to perform a multitude of movements using momentum to tie them together. Moreover, it remains extremely important that we train these relationships to ensure that our bodies move properly.
Momentum that is created in one area of our body is transferred to many areas. Take, for example, the foot. The rear-foot (made up of the calcaneus and talus) will perform a triplane movement known as pronation (see Figure 2). This very necessary movement causes momentum of the rear-foot - moving in abduction, dorsiflexion and eversion (a.k.a. pronation) that will effectively turn on muscles of the mid-foot (as the midtarsal joint unlocks), fore-foot (as the toes splay), all of the calf muscles (as the talocrural internally rotates) and all the way up the body (hip and abs included). The momentum that is created by the heel of the foot meeting an immovable surface (the ground) is what is necessary for the relationships to be facilitated up the kinetic chain. The more momentum, the more the neuromuscular system reacts.
As our leg swings in gait, momentum is created. For example, if we swing our right leg forward as we begin to walk, the momentum of the leg swinging causes our right hamstring to eccentrically load (Figure 1). The hamstring pulls on the ischium. This momentum causes a posterior pelvic rotation of the right innominate bone. Since the sacrum is held fixed with pressure from the sacrotuberous ligament, the result is nutation of the sacrum, which serves to stabilize the SI joints. All this is brought about by the necessary momentum of a swinging leg.
The spine is no different. Our spine, which is the origin of movement and stability, needs momentum (largely in the frontal plane) to allow our pelvis to move so we can walk. These relationships that exist from one segment to another are in need of more study. We are at our infancy in understanding of how movement in one area of the body affects the other segments. However, one thing must be made clear: the more research we accumulate, the more it strengthens the belief that momentum (brought about by the pull of gravity) is one of the critical factors when it comes to human movement.
It is momentum that heightens our nervous system’s ability to react and move. Motor neurons receive their instructions from various areas (sensory neurons, interneurons, the cerebral cortex). The more directly these connections are made, the faster we can respond to a given stimulus. A sensory input (afferent signal) that synapses directly with a motor nerve (efferent impulse) will result in a quick movement. What makes this relationship more effective (i.e., quicker and more efficient) is to have more sensory information coming in. The more information that comes in, the more intelligent our nervous system becomes. Momentum is a major contributor to the nervous system’s ability to develop. With more movement, there is an increase in nervous tissue. As we allow momentum to bathe our bodies in all three planes, it creates rhythmical movements that up-regulate sensory information, making the ensuing motion more skilled and effective. As Charles T. Leonard states: “It is becoming increasingly clear that the nervous system and the motor areas of the brain in particular do not develop appropriately WITHOUT adequate sensory input. Continue to learn [and move] and chances are you will continue to expand your brain – literally. Activity–dependent changes are not limited to dendritic formation. Synapses are strengthened with activity and weakened with inactivity.”
The question is, how do we increase sensory input? That’s easy. We must talk to the body’s sensory system: the proprioceptors. Proprioceptors are what drive us to move. They speak to all aspects of our body, and they unite all the muscles to work in synergy to move us. Proprioceptors respond to movement and momentum. Table 1 is an overview of the role of our proprioceptors.
Let's look at just a few examples of movements using momentum that SHOULD be incorporated in training and conditioning environments. For a more thorough list, please refer to PTontheNET’s Exercise & Flexibility Library.
The Balance Hold 1 Leg with Leg Anterior Reach is a great way in which momentum can be used to decelerate to forward migration of the body. Notice what reactions occur throughout the Kinetic Chain. There is deceleration of closed-chain dorsiflexion (on the planted leg), hip extension in the left hip and posterior migration in both shoulders. Using momentum in this exercise creates an active stretch in the hip flexors (on the grounded leg) under neural control and an opening of the thoracic spine. This exercise is an absolute must for any individual who suffers from "computer posture!"
By creating momentum in certain areas of the body, we can engage the muscular system to a greater degree. This is referred to as a "body driver," and Gary Gray has done extensive research on body drivers. By reaching forward in the Lunge – Frontal with Anterior Reach, the body must fight the generation of forward momentum and the torque created by gravity. This exercise will load the muscles of the posterior chain (i.e., glutes, hams, low back) greater than a normal lateral lunge. This is due to an enhanced reaction of the proprioceptors.
Balance Hold 1 Leg – Overhead Lateral Reach is a unique drill that uses momentum to proprioceptively activate the series of muscles that will stability and mobilize the body in primarily the frontal plane. The human spine mobilizes the body in gait by moving in the frontal plane. With the arms overhead, more torque and momentum can be created, enhancing the spine's ability to attenuate frontal plane forces. For an easier version, perform this movement with the arms to the side of the body.
Many forms of a bicep curl involve a seated or standing version with only the arms in motion. By moving only one segment of the body, the load is distributed over one or two joints, as opposed to the Bicep Curl – Squat. The squat bicep curl allows the legs to aid in the action. By summating force from the ground up, we begin to mimic human function, and we allow forces to be distributed over many joints (as opposed to simply one or two). This creates a much safer situation for the elbow and shoulder complex. Start this movement with no weight in the hands and the visual gaze towards the horizon.
Many individuals feel shoulder and elbow discomfort when performing a heavy set of triceps pushdowns. If you fall into this category, you MUST try the Triceps Pushdown – Lateral Jump. This exercise utilizes the inertia and momentum of jumping side to side with a load from a high elbow position to a full extension. By not restricting shoulder movement (i.e., not keeping your elbows to the side of the body), you create motion and momentum about the scapula and thoracic spine. In human biomechanics, the shoulder complex is a slave to what the scapula and thoracic spine are doing. If they both remain fixed and unable to move, they cannot attenuate forces properly, placing unmitigated stress on the shoulder and elbow complex.
Performing a Bicep Curl with Deadlift is one of the most effective, full body exercises we can do (especially for those who exhibit rounded posture). We all know the benefits of the deadlift as we must fight the downward momentum of the trunk and the weight. Using an integrated approach to train the posterior chain maximizes the involvement of the proprioceptors. During the ascent from the floor, momentum is created by the powerful posterior chain of muscles. This momentum can easily be transferred into the arms for a more powerful curl with minimal stresses placed on the upper body.
The Wood Chop version of the Triceps Pushdown stresses the transverse plane. The muscles throughout the lumbo-pelvic-hip complex must dynamically stabilize the body in the transverse plane to successfully complete this exercise. Notice how high and straight the arms are to begin this exercise. This allow the lats (powerful rotators of the trunk) to begin to pull and create the necessary momentum to which the triceps and trunk can add. Effective motion (especially in the transverse plane) at the ankles, knees, hips, spine (all segments), scapula, shoulders and arms will lead to success in this exercise.
The Lateral Raise – Integrated Squat is another example of using a squat motion to summate forces into and through the shoulders and arms. Most individuals who perform a lateral raise experience excessive elevation in the scapula; this is an indication that the weight is too heavy, and as such, the gleno-humeral joint is unstable (a natural reflex, as type 1-4 mechano-receptors are activated to create hypertonicity in "type 1" muscle: pec. minor, levator scapula and upper traps). Using a full bodied approach, forces can be summated through the body so that momentum can be generated through each segment. Start with no weight and experience the fluidity of this exercise.
Often, our approach to training the core is one of isolation and isometrics. Remember the proprioceptors are the structures that have the greatest influence over muscles, and it is motion and segment-to-segment momentum that turn these proprioceptors on. Performing a Lateral Lunge with an Overhead Press is an unbelievable way to capture the power of the proprioceptors. Will it work the core? Try it! Remember to start with no weight in hand so the motion can be performed fluidly.
There is no doubt that Olympic lifts utilize a lot of momentum, and as such, Olympic weightlifters have some of the strongest bodies (as a whole) of any athletic group. Generating momentum from the ground up (as in the 1 Arm Snatch) is how we were meant to function. As soon as we move one segment of our body, we generate momentum that can be used by adjacent segments, throughout the entire body – this is the brilliance of the human form!
There is an exciting future for training and conditioning. As more research is performed and more is learned about the body, we will be presented with more useful information that can be used to advance our current training and conditioning methods. I urge you to try some exercises that utilize momentum in your own training and conditioning routines. Remember to follow the criteria for each exercise carefully (described in the Exercise & Flexibility Library), and most of all, have fun!
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