The traditional force curve using dead weight is a standard bell shaped curve that demonstrates the greatest force production at the mid range of the movement. Here is some great information from Dave Smitz(The Band Man). Someone who I see has changed, developed and revolutionised the way band fitness training has evolved.
Elastic vs. Traditional Dead Weight Force Production
However, an elastic force curve is more reflective of an ascending straight line. As range of motion increases, force production also must increase to handle the increasing band resistance.
How often are we required to have greater strength at the end of the range of motion as we perform movements like swinging, throwing, lifting, pushing, pulling, or running? How often do we ask athletes to swing through the ball, run through the tackle, explode to the rim, or follow through with the throw?
The point is that elastic resistance challenges the body to increase muscle recruitment through the full range of motion.
As a result the body not only becomes stronger in the end range of movement, it also neuromuscular wise learns how to accelerate the motion and “finish the movement”.
Dead weight neurologically trains us to get stronger through the mid range of the movement but does not create the force challenge at the end of the range motion. Refer to the graph below for more information.
Therefore it does not truly mirror the actually intent or requirement of real world function.
Strength by definition refers to “a muscle’s ability” to generate force against a physical resistance. Therefore when we refer to greater functional factor. Regardless if it is a dead weight or a resistance band the “strength” curve remains a bell shaped curve. However resistance using a dead weight is created by gravity and mass while the resistance created by an elastic band is based on the percentage of stretch. In the world of function this becomes a very important concept to understand if the intent is to finish and accelerate through a movement.
Muscles are dumb. They do not recognise the difference between a dumbbell and an elastic band, as it relates to strength. Instead the muscle “senses” and “reacts” to things like load, changes in velocity, and muscle tension, which is a factor of the type of resistance. Any resistance tool will “drive” the body slightly differently, but from a neuromuscular standpoint deadweight remains “constant” while elastic resistance will create variations in load, tension or velocity of the exercise.
Functional movement is created and constantly influenced by drivers and not artificial stimuli. When you decide to move, you typically do not have to think about the actual movement. Once movement is initiated, your body responds to the driving forces that are placed on it via momentum, gravity and ground reaction. Preparing the body to quickly adapt to changes in forces brought on by these functional drivers is important to maintaining or creating the exact balance, power and strength dictated by the situation.
Example #1: As the foot enters into the ground during a lunge, the ground does not give way, therefore requiring the body to reflexively adjust to the ground impact by decelerating and stopping the body from collapsing into the ground. If the appropriate muscles are not recruited fast enough, the body either collapses or loses its balance as it attempts to return back to the starting position.
What’s the key to successfully completing a lunge? Making sure you are able to return back to where you started and not lose your balance as your foot contacts the ground.
Example #2: If you begin to run fast and something suddenly jumps out in front of you, your body has to quickly decelerate in order to avoid the obstacle. In this example, the obstacle, along with the horizontal and vertical momentum, from the act of running, are the key drivers of function.
If you have trained the body with changing momentums this type of deceleration is instinctive. However if muscles have been challenged at a constant momentum with only vertical driving forces, it will be difficult for the body to adjust on the fly.
In both examples, the ground, gravity, and momentum become the drivers of functional movement and caused muscles to reactively contract. Strength training while sitting or lying down cannot replicate the functional demands placed on the neuromuscular system in these examples. Therefore, free weight exercises or machine based exercises that require non-standing postures become non-loading, non-reactive, artificial stimuli that decrease our response strength and efficiency.
Due to their elastic make-up, bands have the ability to increase momentum, ground reaction, and forces aligned with gravity.
How elastic resistance influences the three key drivers of function
Band training is largely independent of gravity due to the bands’ light mass construction. Furthermore, bands can create force vectors that directly influence the horizontal and rotational planes with changing speeds.
Dead weight is gravity and mass dependent which can only influence movement in a vertical vector at a relatively constant speed.
This training effect becomes extremely exciting when it comes to training ground based functional movements like pushing, pulling, lunging, and reaching or when training other bio-motor skills like running, skipping, carioca, shuffling, hopping, or backpedaling, where the impact of a horizontal force vector plays a significant role in the body’s ability to decelerate and accelerate successfully.
To better understand the importance of training horizontal vector deceleration and force reduction, lets analyse how an anterior cruciate ligament (ACL) of the knee is torn. A typical ACL mechanism of injury is the result of a shear force placed on the ligament during high velocity deceleration created by the foot contacting the ground.
A shear force involves a simultaneous horizontal and rotational vector force with a moderate compression or vertical force. The body’s ability to decelerate a horizontally and rotationally driven force is the key to preventing an ACL disruption. If the body is never trained to identify and quickly respond to high velocity shear forces that entail horizontal and rotational force vectors, the quick millisecond neuromuscular response needed to protect the ACL will in all likelihood not occur. Unfortunately this same scenario is true for several other common orthopaedic related injuries to the low back, shoulder, and ankle.
Dead weight can definitely impact the strength needed to handle the vertical vector forces but cannot biomechanically reproduce the correct line of force needed to mimic shear force vectors. Resistance band training not only can reproduce the exact shear force vectors but with the uniqueness of elastic resistance, it can also create momentum speed changes which will quicken the neuromuscular response time needed to protect the ACL.
The body’s muscle structure functions on the principle that in order for an efficient force producing acceleration (unloading) movement to occur, there must first be an efficient force reducing deceleration (loading) movement. Simply stated, no movement will optimally accelerate forward, upward, laterally, or rotationally until some degree of lengthening or eccentric loading of the primary muscles occurs in the opposite direction. The more explosive the unloading movement, the more efficient and intense the loading phase will be.
You must “Load to Explode”
Interestingly, a resistance band functions similarly. A resistance band must lengthen and store energy before releasing any kinetic energy that will load the muscle. A resistance band is essentially a muscle without a neurological influence when you evaluate its mechanism for releasing energy.
When a series of muscles have to push or pull against a resistance band, they have to not only overcome the increased elastic force or resistance created by the stretching of the band, but they must also optimally control the increased return force which happens to mimic the reloading of most functional movements.
As a result, bands not only strengthen the acceleration phase of the movement, they also better quip the body to handle functional loading or deceleration.
So don’t be shy. Grab a band and work all those forces.
See you soon,
Seize the Day,