Isometric Hip Strength
and Dynamic Stability of Individuals With Chronic Ankle Instability
McCann
RS, Bolding BA, Terada M, Kosik KB, Crossett ID, Gribble PA. J Athl Train. 2018
Aug 7. doi: 10.4085/1062-6050-238-17. [Epub ahead of print].
Take Home
Message:
Although individuals
with CAI present with decreased hip muscle strength, these adaptations may not relate
to dynamic stability during landing from a jump. Hip strength and dynamic
stability should each be considered in CAI rehabilitation programs.
https://upload.wikimedia.org/wikipedia/commons/7/74/Ankle.jpg

Individuals
with chronic ankle instability (CAI)
have decreased muscle strength not only at the foot and ankle, but also proximally
at the hip. It is also known that people with CAI have decreased postural control, especially during functional activities. However, the
influence of hip strength on dynamic stability
during landing in unknown. Therefore, the authors conducted a laboratory study
on 60 participants to determine the relationship between hip muscle strength
and stability during a vertical jump test in people with CAI compared healthy
and ankle sprain coper groups. Participants performed a 5-minute warm-up
followed by vertical jump testing at full effort to record maximum jump height.
To determine dynamic stability outcomes, participants performed 5 jumps to 50%
of their maximum height. When they landed on a force plate, they landed and
stabilized on their single involved limb (or healthy-matched limb) with their
hands on their hips, and held the position for 5 seconds. Stability was defined
as time taken to stabilize the limb in the anterior-posterior and
medial-lateral direction. Investigators then tested for isometric hip
extension, abduction, and external rotation strength through hand-held
dynamometry. The researchers found that on average the CAI group had decreased
hip extension and external rotation strength compared to the coper and healthy
groups; however, there were no differences in hip abduction strength or in
stability outcomes. Additionally, there was no association between hip strength
measures and time to stabilization in CAI or healthy groups, but there was
evidence of increased hip extension strength related to shorter time taken to
stabilize in the coper group.

In
summary, the authors were able to detect decreased hip extension and external
rotation strength measures in individuals with CAI; however, these outcomes
were unrelated to dynamic stability when landing from a jump. It would be
interesting to understand if isokinetic, eccentric, and/or endurance measures
of the hip muscles relate to stability performance given the demands of the
functional task. Additionally, appreciating muscle activation patterns or joint
movement throughout the task would help provide a wholistic picture of proximal
adaptations in this population. However, this study reinforces prior work that
showed proximal alterations exist in people with repetitive ankle sprain, and
that hip strength should be considered when creating a structured ankle
rehabilitation program for these patients. However, as hip strength may not
directly influence dynamic stability, jump-landing technique and other
stabilization exercises should still be included in rehabilitation to improve
CAI outcomes. In all, hip muscle strength assessments should be included
clinically to guide strengthening programs in conjunction with dynamic
stabilization rehabilitation in individuals with CAI.
Questions
for Discussion:
Do you assess hip
muscle strength in your patients with CAI as a part of your structured
evaluation? What hip strengthening programs do you implement into CAI or ankle
sprain patients? What other dynamic stability tests do you include for
individuals with CAI?
Written By: Alexandra F. DeJong
Reviewed By: Jeffrey Driban
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