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

A. Sousa¹, L. Sarmento², A.I. Gouveia², R. Ribeiro², R. Nunes²

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: Postural control has been defined as the control of the body's position in space and requires efficiency of the feedforward mechanisms (early postural adjustments and anticipatory postural adjustments). Bilateral changes in feedforward mechanisms have been demonstrated in individuals with chronic ankle instability (CAI). Nonetheless, the analysis of feedforward mechanisms in tasks close to the mechanisms of injury is still lacking.

Purpose: To evaluate feedforward postural adjustments before single leg drop landing in a dual task context, in both lower limbs, and 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 participants performed the single leg drop landing from a stable support surface onto an unstable surface in a dual task context. The ground reaction forces and center of pressure (CoP) were monitored through two force plates on the two support surfaces to access the time instant of the beginning of CoP displacement to the starting limb and the supporting limb, the instant of contact with the unstable surface and the magnitude of CoP displacement toward the starting limb and to the support limb. The electromyographic (EMG) signal of gluteus medius, rectus femoris (RF), medial gastrocnemius (GM), soleus, tibialis anterior (TA), long (LP) and short peroneal (CP) muscles was collected to assess the timing of muscle activity variation in relation to the onset of CoP displacement and the relative magnitude of muscular activation.

Results: The CAI group presented decreased activity of contralesional RF muscle when assuming the role of support during the CoP displacement toward this limb and an increased activation of the CP, TA and RF ipsilesional muscles between the beginning of forward CoP displacement of this limb till the instant of contact with the unstable support surface.

Conclusions: The CAI group demonstrated bilateral changes in feedforward postural control mechanisms.

Implications: Bilateral feedforward mechanisms should be trained in patients after unilateral ankle sprain.

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
Feedforward mechanisms
Anticipatory postural adjustments

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