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The following is a general guideline for use of the system in each of its operating modes. These
guidelines are of a mechanical nature and do not reflect use of the computer software. They are
presented only as an example to help familiarize the user with the mechanical aspects of
equipment set-up and each of the various modes of operation.
Modes of Operation
The System 4 offers several modes of operation.
Isokinetic Mode – In this mode, the dynamometer acts to control velocity, allowing the subject
to accelerate up to, but no higher than, the maximum speed value selected for each direction of
shaft rotation (accommodating resistance). The subject may freely decelerate or change
direction of movement at any point within the range of motion.
The following general procedure is provided to help clarify use of Isokinetic mode.
Isokinetic Mode Clinical Applications:
1. The Isokinetic mode may be used at higher speeds in order to simulate functional or sports
activities. It can also be used early on in the rehabilitation process to prevent compression
and translation in the knee joint.
2. The Isokinetic mode may be used with differing bi-directional velocities to simulate
functional activities or place the focus of the activity on one specific muscle group.
3. There is a 15-degree physiologic overflow in strength on each side of the end ROM (30º
total carry-over) with a limited range of motion strengthening program performed
isokinetically (Halbach, 1985.)
4. Select con/ecc or ecc/con to isolate one muscle group.
5. Exercising at a specific speed has shown strength gains that overflow to both faster and
slower speeds. However, there is enough research to demonstrate that by exercising at
every 30 degrees/second, physiological overflow will occur with regards to specific
strengthening at each speed exercised (Davies, G.J., 1987.)
6. In the Isokinetic mode, the Force-Velocity relationship of muscle dictates that as speed of
contraction increases concentrically, the muscular tension (and, therefore, torque)
decreases. (Davies, G.J., 1987.)
7. A velocity spectrum is recommended that will start the subject at either a high or low speed,
depending on the pathology and status of the subject, and progress to other speeds.
Varying the number of repetitions (i.e., less reps at slow speeds, more reps at high speeds),
will help keep the work performed consistent over the range of the velocity spectrum.
8. Exercising at higher speeds has shown excellent benefits for endurance gains. This will limit
compression on joints, tension developed in the muscles and tendons, and generally allows
the subject to do larger numbers of sets or repetitions; which transfers to daily activities.
9. Keep in mind the stretch shortening cycle. It has been found that an eccentric contraction
performed before a concentric contraction results in a more forceful concentric contraction
than a concentric contraction performed alone (Duncan, P., et. al., 1989). High speed
contractions followed by slow speed contractions will simulate an isolated plyometric
activity.
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