POSTURAL ADJUSTMENTS DURING <EM>SINGLE LEG DROP LANDING</EM> IN SUBJECTS WITH CHRONIC ANKLE UNSTABILITY

A. Sousa¹, R. Ribeiro², A.R. Nunes², L. Sarmento², A. Gouveia¹

¹Escola Superior de Saúde/Instituto Politécnico do Porto, Physiotherapy, Centro de Investigação em Reabilitação, Porto, Portugal, ²Escola Superior de Saúde/Instituto Politécnico do Porto, Centro de Investigação em Reabilitação, Porto, Portugal

Background: Chronic ankle instability (CAI) involves deregulation of postural control mechanisms and is estimated to occur in 70% of the individuals after ankle sprain. Nonetheless, there is still no consensus regarding the postural dysfunction that leads to the perpetuation of CAI. The transition from a dynamic task to a static one in conditions similar to those of the injury mechanism has been referred as capable of revealing those deficits.

Purpose: To evaluate the bilateral postural adjustments during single leg drop landing on an unstable surface in a dual task context in individuals with CAI.

Methods: A cross-sectional observational study was carried out with a sample of 28 athletes distributed into two groups, one with and one without CAI, according to the criteria of the International Ankle Consortium. The electromyographic activity of the muscles of the gluteus medius (Gluteus M.), rectus femoris (RF), medial gastrocnemius (GM), soleus, tibialis anterior (TA) and long peroneal (LP) and short (CP) of both lower limbs, as well as the reaction forces of the ground were collected during single leg grop landing in a dual task context. The vertical component of the ground reaction forces was used to identify the instant of the landing, as well as the moment the participant initiated the single leg standing. The position of the center of pressure (CoP) was calculated to identify the time instant where its stabilization occurred. At intervals up to and after the CoP stabilization, the range of CoP displacement and standard deviation, as well as the magnitude of relative muscle activity, were used for analysis.

Results: Comparing to the control group, the CAI group presented: 1) decreased Gluteus M., RF and TA activity in the ipsilesional limb and decreased RF activity in the contralesional during landing; 2) decreased time required for stabilization and in the amplitude of CoP anteroposterior displacement in the ipsilesional limb; and 3) decreased GM and CP activity in the ipsilesional limb and increased LP activity in contralesional limb after stabilization.

Conclusions: Individuals with CAI present deregulation in postural control mechanisms in both ipsilesional and contralesional lower limbs subsequent to an unilateral ankle sprain. These impairments were expressed through decreased ipsilesional lower limb muscle activity during landing and stabilization periods and decreased RF activity combined with increased LP activity during landing and stabilization periods, respectively, in the contralesional limb.

Implications: Neuromotor rehabilitation after unilateral ankle sprain should consider both limbs in the rehabilitation process.

Funding acknowledgements: This work was supported by the Fundação para a Ciência e Tecnologia (FCT) through R&D Units funding (UIDB/05210/2020).

Keywords:
Chronic ankle instability
Postural control
Neuromuscular activity

Topics:
Disability & rehabilitation
Musculoskeletal: lower limb
Sport & sports injuries

Did this work require ethics approval? Yes

Institution: Escola Superior de Saúde, Instituto Politécnico do Porto

Committee: Ethics committe from Escola Superior de Saúde, Instituto Politécnico do Porto

Ethics number: 900