Most plantar/dorsiflexion testing is done in the modified sitting position.
1 First you need to get the machine to roughly the right place.
Every machine is different but they all have a section in the software (or users manual) that tell you how to get the seat and dynamometer to roughly the right position to test either the right or left ankle. It will also tell you which attachments you need to stabilise and fix the subject to the machine.
2 Once in roughly the right position sit your subject on the chair.
Now adjust the height of the dynamometer and/or stabiliser to get 90 degrees of flexion at the knee as seen below.
3 Now strap the subject to the chair or stabiliser with the appropriate strap and fix the foot using the straps and adjustments avaliable.
4 Now align the the axis of rotation.
The axis of rotation goes from the machine (see the blue star below) and extends through the lateral condyle. To check the alignment simply plantar and dorsiflex the ankle and ensure the heel does not lift from the footplate (don't be tempted to strap in the foot tighter if the heel lifts it does not work I've tried!).
Here the lateral condyle is shown as the solid blue star. The actuator axis (the blue star on the machine and the centre of the lever arm's rotation) should be opposite the lateral condyle (the blue star on the subject).
5 Set the anatomical zero if the machine requires this (some do and some don't) the anatomical zero is when the ankle is in neutral (this gives the machine a reference point).
6 Set the range of motion
For plantarflexion try to be between 40-70 degrees. Then set the range of motion for dorsiflexion try to be between 20 and 40 degrees (remember these are the values shown on the machine they are not necessarily the true range of motion).
8 Set gravity correction if you want to!
TIP: The effects of gravity help the plantarflexors but hinder the dorsiflexors, however, if you always test the same person without gravity correction your results will be generally consistent (as long as the subject does not gain or loose allot of weight! Watch out for heavy and light footwear).
9 Set an exercise protocol
We will presume you are going to use isokinetic exercise!
Movement type: Concentric or eccentric? For most subjects a concentric/concentric test will be sufficient. Only move on to eccentric testing if you are interested in a specific muscle or the concentric/concentric results show no problems but you are convinced one exists.
Speed: Generally I recommend a medium joint speed for testing strength. So what is a medium joint speed? Well at any joint a medium speed (in my opinion) is one which gives 1 degree per second for every 1 degree range of motion (what I hear you shout. Think of it like this we have already set a range of motion from plus 20 degrees dorsiflexion to say 40 degrees of plantarflexion then a medium speed would be 60 degrees per second!). However, in the ankle some speeds have been used allot in the research these are 30, 60, 90 and 120 degrees per second for strength and 240, 300 and upwards for endurance. So simply choose one of these speeds to suit your requirements.
Repetitions:
To test strength 3 repetitions should be sufficient (best of 3 as they say). In the real world most subjects don't do well on at least two of these so we are up to 5 repetitions for strength. If you are testing a patient then go for 10 repetitions as they often get better results after 5 but never after 10.
For endurance set a time limit if you can or if you can't a number of repetitions the subject will never complete (you are interested in how long they can carry on for). For time try 5-10 minutes and for reps choose 500 and above.
TIP: Do not use trial repetitions as the machines don't generally record them and you can be guaranteed if you include them your subject will hit peak torque during them. Use more sets instead.
Number of sets: For a strength test one should be enough, but remember we have not used trial reps so we need at least one set to warm up with and get used to the machine and then one set to do the actual test this makes 2 for patients I always use 3 sets (best of 3 to a patient this makes sense). For an endurance test it is one set of 10 to warm up and get familiar with the machine and then just one big long maximal set.
Rest between sets: Always go for 15 to 20 seconds.
10 Start the test!
TIP: remember to get out of the way of the moving limb!
11 Interpretation of results.
First look at the peak torque these figures tell us how strong the subject is and can be compared to the opposite side. If you have tested both sides you should look to see if the sides are within 10 percent of each other (this is a good balance).
TIP: remember there will be two of these figures if you have used concentric/concentric testing there will be on for the plantarflexors and one for the dorsiflexors. If you have used concentric/eccentric testing you will have one results for concentric and one for eccentric.
Now check the figures which show one half of the test to the other i.e. the concentric/concentric ratio or the concentric/eccentric ratio. In this section you should see that the plantarflexors are roughly 70 percent stronger than the dorsi flexors (a ratio of 170 percent or 30 recent if you compare dorsiflexors to plantarflexors). For the concentric/eccentric results you should expect the eccentric value to be 30 percent higher in both sets of figures (although I have seen much higher eccentric plantarflexion figures).
TIP: If the patient does not have normal muscle strength values then these should be returned using the appropriate isotonic exercises. If this cannot be achieved then isokinetic treatment should be considered using the appropriate protocol.
Most inversion/eversion testing is done in the modified sitting position.
1 First you need to get the machine to roughly the right place.
Every machine is different but they all have a section in the software (or users manual) that tell you how to get the seat and dynamometer to roughly the right position to test either the right or left ankle. It will also tell you which attachments you need to stabilise and fix the subject to the machine.
2 Once in roughly the right position sit your subject on the chair.
Now adjust the height of the dynamometer and/or stabiliser to get 90 degrees of flexion at the knee and the ankle as seen below.
3 Now strap the subject to the chair or stabiliser with the appropriate strap and fix the foot using the straps and adjustments avaliable.
4 Now align the the axis of rotation.
The axis of rotation goes from the machine and extends through the center of the calcaneous. To check the alignment simply invert and evert the ankle and ensure the heel does not lift from the footplate (don't be tempted to strap in the foot tighter if the heel lifts it does not work I've tried!).
5 Set the anatomical zero if the machine requires this (some do and some don't) the anatomical zero is when the ankle is in neutral (this gives the machine a reference point).
6 Set the range of motion
For eversion try to be between 20-40 degrees. Then set the range of motion for inversion try to be between 30 and 60 degrees (remember these are the values shown on the machine they are not necessarily the true range of motion).
8 Set gravity correction if you want to!
TIP: The effects of gravity are negligible in this position.
9 Set an exercise protocol
We will presume you are going to use isokinetic exercise!
Movement type: Concentric or eccentric? For most subjects a concentric/concentric test will be sufficient. Only move on to eccentric testing if you are interested in a specific muscle or the concentric/concentric results show no problems but you are convinced one exists.
Speed: Generally I recommend a medium joint speed for testing strength. So what is a medium joint speed? Well at any joint a medium speed (in my opinion) is one which gives 1 degree per second for every 1 degree range of motion (what I hear you shout. Think of it like this we have already set a range of motion from plus 30 degrees eversion to say 40 degrees of inversion then a medium speed would be 70 degrees per second!). However, in the ankle some speeds have been used allot in the research these are 30, 60, 90 and 120 degrees per second for strength and 240, 300 and upwards for endurance. So simply choose one of these speeds to suit your requirements.
Repetitions:
To test strength 3 repetitions should be sufficient (best of 3 as they say). In the real world most subjects don't do well on at least two of these so we are up to 5 repetitions for strength. If you are testing a patient then go for 10 repetitions as they often get better results after 5 but never after 10.
For endurance set a time limit if you can or if you can't a number of repetitions the subject will never complete (you are interested in how long they can carry on for). For time try 5-10 minutes and for reps choose 500 and above.
TIP: Do not use trial repetitions as the machines don't generally record them and you can be guaranteed if you include them your subject will hit peak torque during them. Use more sets instead.
Number of sets: For a strength test one should be enough, but remember we have not used trial reps so we need at least one set to warm up with and get used to the machine and then one set to do the actual test this makes 2 for patients I always use 3 sets (best of 3 to a patient this makes sense). For an endurance test it is one set of 10 to warm up and get familiar with the machine and then just one big long maximal set.
Rest between sets: Always go for 15 to 20 seconds.
10 Start the test!
TIP: remember to get out of the way of the moving limb!
11 Interpretation of results.
First look at the peak torque these figures tell us how strong the subject is and can be compared to the opposite side. If you have tested both sides you should look to see if the sides are within 10 percent of each other (this is a good balance).
TIP: remember there will be two of these figures if you have used concentric/concentric testing there will be one for the invertors and one for the evertors. If you have used concentric/eccentric testing you will have one result for concentric and one for eccentric.
Now check the figures which show one half of the test to the other i.e. the concentric/concentric ratio or the concentric/eccentric ratio. In this section you should see that the invertors are roughly 30 percent stronger than the evertors (a ratio of 130 percent or 70 recent if you compare evertors to invertors). For the concentric/eccentric results you should expect the eccentric value to be 30 percent higher in both sets of figures.
TIP: If the patient does not have normal muscle strength values then these should be returned using the appropriate isotonic exercises. If this cannot be achieved then isokinetic treatment should be considered using the appropriate protocol.
