Isokinetic Muscle Strength Testing

With the recent success of Team GB at the Rio Olympics people have been inspired to take up new or previous sports. 

However muscle weaknesses from previous injuries may be limiting the ability of these individuals to perform these sports without risking re-injury. Below we explore how isokinetic muscle strength testing at Perform Cardiff can be utilised in order to assess muscle strength and tone in order to ensure a safe return to sport. 

Isokinetic movement is movement against resistance at a constant speed.  It is one method of assessing maximum strength and is widely used in medical and scientific research, both as a measurement of strength and as a strength training tool. Clinically it is often used to assess strength in particular muscle groups pre and post-operatively. 

There are a number of machines available to perform isokinetic testing and exercise, all of which vary slightly but allow multiple parameters to be measured and calculated. At Perform Cardiff we use a Cybex machine which offers 4 types of resistance/movement and 3 contraction cycle types with numerous feedback options.  Common testing formats include comparison of strength in muscle groups between left and right sides, or between opposing muscle groups on the same side.  Resistance can also be applied to measure strength during different types of muscle contraction. The results can then show if there is an imbalance between sides/muscle groups and can also indicate pathology. This can help focus strength training to those specific areas of weakness (both muscle group and contraction type) and help guide both the patient and therapist to achieve optimal outcomes from rehabilitation.  It can also be used to monitor progress and motivate the patient during prolonged rehabilitation.

Anyone who suspects they may be symptomatic due to poor strength or muscle imbalance may benefit from isokinetic strength testing.  Isokinetics is considered the gold standard test for muscle strength following knee ligament reconstruction (most commonly the anterior cruciate ligament).  It is also frequently used following shoulder surgery (rotator cuff repair and shoulder stabilisation) where the results can be useful in determining when an athlete is ready to return to sport or activity. Results are produced immediately by the computer and will be interpreted by the physiotherapist undertaking the testing.

In addition to strength testing the Cybex machine can also be used to perform strength training. This enables patients to perform strength training exercises against the resistance of the machine. Following isokinetic strength testing, specific parameters of training can be utilised to target the specific areas of deficit. The patient works against the resistance of the machine. This is usually conducted over 4-6 sessions before a re-test in order to assess the improvements made.

If you would like more information on Isokinetic strength testing please feel free to contact us on: 029 2073 1112 or visit our website at

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