It has been my experience that eccentric testing with an "isokinetic devices" has not been reliable. However, for rehabilitation practically, I have utilized the passive mode and had individuals resist on that mode and it has worked very well with shoulder int. and ext. rrot. (In the 40 deg. scaption position and in the 90 deg. scaption position). Also, utilizing seated and standing positions worked well to help with trunk stabilization. Utilizing the safety features such as torque limits, adjustments to speed, ROM, proper education/demonstration etc. is essential.  Utilizing the concentric/concentric mode for testing, over the years has been a very good valid and reliable (e.g. utilizing manufacturers recommendations) manner to make strength assessments.. I hope this helped.

Thank you Morufu and Paul !!! Both answer were very helpful. I think I will use con/con mode for shoulder torque assessment.....

Best regards.

I am a contracted clinical instructor for Biodex. Training or testing using eccentric muscle actions is frequently referred to in the literature. Yet there are rules for eccentric muscle actions. Most of the studies have used isokinetic dynamometers, like the Biodex, or devices fabricated by the research team. While it is known that in studies of in vitro muscle preparations force increases above maximal isometric levels, exact velocities of movement in in vivo studies of eccentric muscle actions are an unknown quantity, therefore most have used relatively low velocities of movement. With the Biodex under passive and eccentric conditions the selection of velocities above 60 deg/sec results in a prompt asking if you really want to use the “HIGH” velocity you have selected.

We have used the S-4 to good effect in training and testing a number of joint systems and movements with eccentric muscle actions. If you go to my profile page on Research Gate you will find an abstract of a Case Study presented at ACSM’s Annual Meeting in San Diego in May, 2015. (Harding FV, R Ghatan, C Chaney, KW Mengel, J Chen, J Loyo. Clinical Case Study: Shoulder Injury – Senior Tennis. Med Sci Sports Exerc. 47(5S): S16, S17, 2015. Harding FV, R Ghatan, C Chaney, KW Mengel, J Chen, J Loyo (2015). Clinical Case Study: Shoulder Injury – Senior Tennis. American College of Sports Medicine 62nd Annual Meeting, San Diego, CA, May.)

When testing or training using the S-4, the best results will be achieved in Passive Mode. The Eccentric Mode is called Reactive Eccentric. The problem with the Reactive Eccentric Mode is the requirement for the subject to produce a percentage of the Torque causing the eccentric muscle action to trigger the dynamometer to begin the “eccentric” movement. Since a true eccentric muscle action occurs when a muscle is attempting to shorten against an overwhelming force that actually causes the muscle to be forcibly lengthened, this is not always the case in Reactive Eccentric Mode, in fact, the torque produced is generally less than a maximal isometric torque. In the Reactive Eccentric Mode, the limiting torque in the direction of movement is either too great for the subject to successfully initiate the movement, or too small to allow for the dynamometer to overcome the muscle torque created by the subject, causing the device to stop.

The answer to the problem is to use the Passive Mode. In Passive Mode, you have the ability to set the velocity of movement (as previously stated velocities of 60 deg/sec or higher cause a warning prompt to appear), and the maximum torque that must be overcome to stop the device. Velocities of 30 to 60 deg/sec are what have usually been reported in the literature; we have found that persons may have a problem developing torque initially with speeds above 60 deg/sec. However, after exposure to the exercise most can utilize velocities above 120 deg/sec. The problem with high velocities with movements having small ranges of motion is that the person becomes confused about which way they are supposed to be exerting effort. In the passive mode, the machine will move through the full range of motion set by the investigator, at the pre-set velocity, and the subject must attempt to “STOP THE MACHINE”. If you have set the Torque limit high enough to attain a true Eccentric Muscle action for the entire movement they will not be able to stop the machine and it will move at the pre-selected velocity for the desired number of repetitions.

When using subjects who have learned to use the device with eccentric muscle actions we have observed the requisite increase in torque producing capabilities across the range of 10 – 120 deg/sec. Some people experience the loss of torque producing capabilities at lower velocities, some at velocities in excess of 120 deg/sec. We hypothesized, and it has been substantiated by experience, that the loss of torque producing ability at higher velocities is a sign we have reached the physiological limit of eccentric muscle actions observed in the force – velocity curve for that individual, or it is a function of a combination of innate athletic ability and learning.

When setting up the S-4 for eccentric testing or training, go to the protocol screen. Select Add and name your protocol. Select Test or Exercise (the test set up screen for ROM has the gravity correction factor at the bottom of the screen below the calibrate position button, exercise does not). Select Bilateral or Unilateral. Select Passive Mode, the joint system, and movement to be trained or tested. With shoulder IR/ER you have two choices – Modified Neutral and 90/90. Modified Neutral is the “safest,” 90/90 is most appropriate for individuals involved in throwing and over-head/over-hand striking activities. For purposes of stabilization it is best to use a seated position, though a standing position can be utilized. Select the number of sets and set the different velocities for each set and direction of movement, THEN SET the TORQUE, we use at least 250 ft-lbs (340 Nm) for IR/ER to insure no one can stop the machine. When setting contraction type use CON/CON, any use of ECC whether CON/ECC, ECC/ECC, or ECC/CON will result in the use of the Reactive Eccentric Mode of operation.

Normative data for IR/ER is available on-line at Biodex, is in the database manager on the computer with the S-4, and in the manual. The velocities reported for IR/ER suggest they are for concentric isokinetic tests. You will be developing the normative data for you study population since to my knowledge, no normative data exists for eccentric movements. If you have further questions I am here on Research Gate.