Isokinetic strength testing of the hip - elderly participants

[Tom Chesters]

Hi all.

I have an elderly osteoporotic population (65-70 years, T score -2.5--4), in whom I wish to measure hip muscle strength (both flex/ext, and abd/add). We have a Biodex System 3 (isokinetic dynamometer) perfectly capable of doing this. However, it is an intimidating piece of equipment and the seat/positioning is far from comfortable when performing these tests. Due to the relatively frail nature of my participants, I was considering swinging the dyno arm unit 180degrees, and positioning a rehab bench next to it. The dyno unit provides ample adjustment to position the arm in the correct place, leaving the participant able to lie comfortably on the bench and perform the tasks. The potential negatives of this configuration include the lack of restraining straps, the difficulty of consistent participant positioning, and the potential loss of power through the bench. However, pilot testing suggests these are not significant issues when care is taken with positioning. I wondered if (1) anyone had any experience of doing this, or (2) anyone with greater experience of strength testing than me (I am relatively inexperienced) had a strong opinion on how this may influence the validity of my data!

Thanks very much for your help

[Joanne Parsons]

Re: Isokinetic strength testing of the hip - elderly participants

Hi there,
Have you considered testing them in a standing position? A more comfortable position, and probably more functional. I'm just beginning a study using a standing hip testing protocol (both ab/add and flex/ext), although in a younger population. Let me know if you'd like more information.
Joanne

[Elizabeth Russell Esposito]

Re: Isokinetic strength testing of the hip - elderly participants

Standing will work, just make sure that their standing leg is elevated (on something heavy/stationary that will not move) to allow the limb you are testing to swing throughout the range of motion. The only problem I have run into with testing in a standing posture is that the joint torques are somewhat lower than you may get in other positions (particularly for hip extension). Try having your subjects position themselves in a prone position for hip extension. Ideally, the hips would be just off the edge of the rehab bench you are using with the contralateral limb still supported.

Elizabeth

[Tom Chesters]

Re: Isokinetic strength testing of the hip - elderly participants

Joanne, Elizabeth - Thanks for the suggestions. I had not considered standing as an option but it seems like it may work well. A contraction with more 'functional' significance would suit my study, in addition to it being more comfortable for my participants. With respect to the lower joint torques (in comparison to supine testing) this should be OK assuming all participants are tested in the same condition. Joanne - what dyno are you using? A Biodex? I need to pilot this to check its feasibility (unfortunately this will have to wait as the lab is now closed for xmas/new year)

Tom

[Joanne Parsons]

Re: Isokinetic strength testing of the hip - elderly participants

Hi Tom - I'm using a Biodex system 3. Modifications I've had to make include getting a wooden box/platform made to ensure a large enough surface area for the subject to feel secure. I have the subject stand with their back to the dyno chair when testing ab/add. That way I can use velcro straps to stabilize them against the chair. For flex/ext I have the subject turn so that their tested side is closest to the dyno head.
I can send you some pictures; I'm at umparso3@cc.umanitoba.ca - we can continue the conversation there, if you like.
Joanne