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General Principals with Impulse Inertial Exercise


Controlling inertia requires constant acceleration and deceleration, which is, as you know, difficult if not impossible to train with manual manipulative techniquesThe Impulse slows down the functional control of acceleration and deceleration so that the therapist can now teach the patient movement patterns while learning to accommodate pain or lack of ROM.  The movement is slowed by the inertial input of the weight (mass) moving on the gravity free track.  With combined input from the therapist and inertia, control of movement is easily learned; in other words, motor programming is developed.

As a machine, its operation is very simplistic.  A sled glides horizontally along a track with extremely low friction.  Attached to the sled is a rope, which is guided along a system of ImpulsePTpulleys and can then be pulled by the user.  In the pulley route, a configuration of pulleys are placed below and centered on the track.  When a user pulls the rope, the sled accelerates along the track (free of gravity relative to the user).  When it passes the centered pulleys, the direction of motion of the rope is reversed and the user will receive a pulling energy in the rope equal to the inertia created by the acceleration of the sled.  In this way, the user generates all of the forces concerned in the exercise. 


As an instrument, the Impulse offers the ability to quickly train coordination. This means the development of motor programs.  Hands-on training with the patient and an Impulse is the quickest way to develop a functional motor program.  You, as the trainer/therapist, must understand the technique of motion that you are attempting to train.  By connecting the patient to the Impulse with the appropriate attachment, and then performing the exercise yourself (with the patient feeling and following your motion) with the correct technique and intensity (at a level of performance you believe the patient can perform), the patient will immediately understand the motion you are conveying.  No amount of verbal description can match this experience of feeling the motion.

tonic Two fundamental techniques of motion can be utilized in training users with the Impulse. Tonic, which trains synergistic co-activation of agonist and antagonists; and phasic, which trains high acceleration contraction and relaxation.  With the tonic technique the user maintains tension on the rope during the entire exercise session. The user is therefore proprioceptively engaged with the moving sled at all times. With the phasic technique, the user disengages from the sled at the end of each cycle.  Therefore, re-engagement of the sled requires an anticipatory pre-programmed motor program to enact smooth control.  Each technique utilizes mechano-receptors proprioceptively tracking the force of inertia and motion of the body to build confidence in better functional motion.


phasicAs the two waveform charts demonstrate here, the forces created by the body with each technique are radically different.  And so, the control of each technique is different.  Regardless of the technique used, it is the changing state of inertia in the exercise, which influences the development of motor programs. 


Inertia outside the body stimulates functional proprioception in the patient as well as the training therapist.  The therapist, possessing a functional motor program, assists control by actively doing the movement pattern with the patient.  As the therapist teaches the motion (slow motion mode or 15+ pounds), the patient senses proprioceptive input from both the therapist’s motion and the inertia of the weight.  When input from the therapist is removed, the patient, having gained the proprioceptive awareness of inertia, is able to control movement independently.  The weight is then reduced, increasing acceleration, allowing for development of actual functional high-speed activity.  This is done in a matter of minutes, and in many cases, a few seconds.  Functional levels of control can be trained even with chronic pain, limited ROM, or edema. 

The more you practice training techniques with the Impulse the better you become at orchestrating it within your practice.  When you first pick up a musical instrument, an instructor teaches you a few cords or notes; then, with practice and use you can play a very difficult piece.  With the Impulse, at first, you may only have the knowledge and ability to treat problems such as rotator cuff impingement or ACL arthroscopic repair.  Then, with time and experience, you develop the ability to treat anything from head injury, stroke, or even RSDS.


The Impulse utilizes high frequency (repetition/second) low resistance exerciseIt does not build strength; it develops coordination.  It is rarely possible to work through an entire range of motion in the same exercise. The system is not designed with that goal in mind.  The Impulse trains and exercises functional concentric and eccentric motor activities. Portions of the ROM, such as in a PNF pattern, may be broken down into segments of motion.


The Impulse is unlike traditional pulleys in that the eccentric contraction, using the phasic technique, takes place in a very short period of time (sometimes on the "catch") and not throughout the entire ROM.  This makes the eccentric contraction more functional and allows two variables of control in contrast to isotonic (resistance) or isokinetics (speed-rads/sec.).  You may increase the weight, keeping the frequency rate the same, or increase the frequency rate, keeping the weight the same.  Both will have the effect of increasing the total force by the equation: mass x acceleration = force.


Techniques utilizing the Impulse for rehabilitation are different from those used in high performance training.  In general, rehabilitation techniques use a weight and frequency, which is appropriate for the disability (1 to 3 reps/second depending upon biomechanics, injury level and weight selection). In high performance training, the goal is to gradually decrease the weight on the sled (to only the sled as soon as possible) while increasing the frequency (athletes reach 3 to 6 reps/second depending on the biomechanics of the motion and weight selection).


The underlying activity utilizing concentric and eccentric contractions is that of acceleration and deceleration.  As the sled is accelerated via a concentric contraction, it will continue moving at a velocity created by the acceleration phase until it is decelerated, or stopped, via an eccentric contraction (the "catch").  The concentric contraction is voluntary while the eccentric contraction is reflexive, thus training functional motion activity.  Patients should be encouraged to increase their frequency rate to the highest pain free level, as soon as possible, thereby progressing their functional capabilities.

Proper training technique is extremely important.

At the beginning of an exercise, an inexperienced patient may attempt to accelerate the sled before it has been properly decelerated, producing a "jerky" motion. This will produce uncoordinated motion and frustrate the patient.  Hands-on training, by the trainer, with proper technique of an uninvolved area of the body is a must. Always initially teach the patient to use the Impulse with an uninvolved limb.  This will provide the patient an experience of confidence with the instrument.  When proper motive techniques are trained (1 to 2 minutes max of hands-on training), motor control will become obvious and progress quickly.  After training the uninvolved limb (at a level of intensity commensurate with the involved areas ability to produce force), the patient should continue the exercise for at least 30 seconds.   This process is important in that it ingrains the newly learned motor programs.  Coordinated cross over to any other portion of the body is generally instantaneous after this process.  The involved area will now progress quickly (30 - 90 seconds from hands off training) in training