The VERT Velocity Enhanced Resistance Training System represents a new and unique application of fitness technology. VERT resistive training and rehabilitation machine employ's computerized feedback control of both resistance and motion during exercise. The VERT Velocity Enhanced Resistance Training System, for the first time, allows the machine to dynamically adapt to the activity being performed rather than the traditional approach of modifying the activity to conform to the limitation of the machine. The case studies in applied biomechanics demonstrate the importance of considering the true patterns of motion in determining fitness. Of equal importance is the need to maintain the same pattern of motion in training or rehabilitation as that required to perform the actual activity. The VERT system resistive training technology is able to achieve this basic requirement.
The VERT system consists of a number of training, diagnostic and rehabilitation machines designed to accommodate varying types of body and limb movement. Each machine utilizes a passive hydraulic resistance mechanism operating in a feedback-controlled mode under the direction of the system's computer. A simplified functional description of this mechanism and its operation using feedback control is described in the following paragraph.
A standard hydraulic cylinder is attached to an exercise bar by a mechanical linkage. As the bar is moved, the piston in the hydraulic cylinder moves pushing oil out of one side of the cylinder, through a valve, and back into the other side of the cylinder. When the valve is fully open there is no resistance to the movement of oil and thus no resistance to the movement of the bar. As the valve is closed, it becomes harder to push the oil from one side of the cylinder to the other and thus harder to move the bar. When the valve is fully closed, oil cannot flow and the bar will not move. In addition to the cylinder, the resistance mechanism contains sensors to measure the applied force on the bar and the motion of the bar. Now assume the valve is at some intermediate position and the bar is being moved at some velocity with some level of resistance. If the computer senses that the bar velocity is too high or that bar resistance is too low, it will close the valve by a small amount and then check the velocity and resistance values again. If the valves are not correct, it will continue to close the valve and check the values until the desired velocity or resistance is achieved. Similarly, if the bar velocity is too low or the bar resistance is too high, the computer will open the valve by a small amount and then recheck the values. This feedback loop will continue with the valve being opened by small amounts until desired velocity or resistance is achieved. The feedback cycle occurs hundreds of times a second so that the user will not experience perceptible variations from the desired parameters of exercise.
There are a number of advantages in such a resistance mechanism over devices that employ weights, springs, or active components such as motors or pumps. One significant advantage is safety. The passive hydraulic mechanism provides resistance only when the user pushes or pulls against it. The user may stop exercising at any time, such as during rehabilitation if pain or discomfort is experienced, and the exercise bar will remain motionless. With other equipment types providing active resistance, the bar will continue to push against the user and possibly cause injury. Another advantage is that of bi-directional exercise. They hydraulic mechanism can provide resistance with the bar moving in either direction. Opposing muscle groups can be trained in a single exercise. Two additional problems associated with weight training, noise and inertia, are also eliminated. The hydraulic mechanism is virtually silent and full resistance is maintained at all speeds. With weights, users commonly "cheat" by moving the bar more rapidly at the beginning of a stroke and then "coasting" to the end of the stroke.
In addition to the advantages just described, the primary advantage of VERT's resistive mechanism is that the pattern of resistance or the pattern of motion experienced by the user during exercise is fully programmable. The concept of applying a pattern of resistance or motion to training and rehabilitation is new to many practitioners in these fields. Prior to the introduction of the Velocity Enhanced Resistance Training System, fitness technology could provide only limited modes of resistance and motion. Barbells or weights of any type can provide an isotonic or constant resistance type of training only if they are moved at a constant velocity. Typically, users are instructed to move the weights slowly up and down in order to avoid the problem of inertia previously mentioned. Weights used with cams or linkages that vary mechanical advantage can provide a form of variable resistance, but the pattern is always fixed and the varying mechanical advantage causes a variation in velocity that increases inertial effects. Users must move the weights even more slowly to preserve the resistance pattern. This type of exercise is "artificial" in that it does not approximate the body or limb motion pattern of any actual activity.
Isokinetics or constant velocity training equipment is a relatively new fitness technology that has enjoyed wide acceptance, especially in the field of rehabilitation. These mechanisms typically utilize active or passive hydraulics or electric motors and velocity-controlling circuitry. The user or practitioner selects a constant level of velocity for exercise and the mechanism maintains this velocity while measuring the force exerted by the subject. Devices of this type eliminate the inertia problems associated with weights, allow training at velocity levels that more closely approximate actual activities, and provide a means for recording and reporting performance. While demonstrating significant advantages over weight-based systems, isokinetics systems, by design, contain a serious limitation. There are virtually no human activities that are performed at a constant velocity. The very nature of movement requires continual acceleration and deceleration. When a person leans to walk, ride a bike, or even sign his name, he is "programming" a pattern of acceleration that may be repeated at different rates and with different levels of force, but always with the same pattern unique to that activity. To train, rehabilitate, or diagnose at a constant velocity is to change the very nature of the activity being performed.
The VERT Velocity Enhanced Resistance Training System has been designed to consider every movement or exercise performed by a user to be a pattern of continuously varying velocity or resistance. This pattern may be set using direct measurement of subject motion by the system, it may be copied from the results of performance analysis or the pattern may be "designed" or created by the user or practitioner as a goal of training or rehabilitation. Exercise patterns are stored in computer memory and can be recalled and used each time a subject trains. During exercise, the computer uses the pattern to adjust bar velocity or bar resistance as the subject moves through the full range of motion. In this manner, the motion parameters of almost any activity can be closely duplicated by the exercise system. Thus, assessment, training, or rehabilitation may be performed using the same pattern as the activity itself.
The VERT Velocity Enhanced Resistance Training System contains numerous features to enhance the application of this advanced fitness technology. Individual exercise or rehabilitation programs, which are sequences of exercises, can be created and saved on computer diskette. Users can perform their individual program at any time merely by inserting their diskette in the computer. Measurements of exercise results are automatically saved on the same diskettes and progress is monitored by comparing current performance levels to previous ones. Performance can be measured and saved in terms of strength, speed, power, repetitions, quantity of work, endurance and fatigue. Comparisons of these quantities can be made for flexors versus extensors, right limb versus left limb, as well as between different individuals. Visual and audio feedbacks are provided during exercise to insure that the subject is training in the proper manner and to provide motivation for optimal performance.
VERT gets you to your performance goals faster more efficiently and safer than any other work out to date.
From "BIOMECHANICS AND ITS RELATIONSHIP TO FITNESS TECHNOLOGY"
G.B. Ariel, Ph.D.