TITLE: Evaluation of stability of balance recovery from unpredictable perturbations through the compensatory arm and leg movements (CALM) scale
AUTHORS: Marina Torres Betelli, Patrícia Sayuri Takazono, Caroline Ribeiro de Souza, Julia Ávila de Oliveira, Daniel Boari Coelho, Luis Augusto Teixeira

[DESCRIPTION]
<div class = "text-blocks"><div class = "text-block"><span>The scale for evaluation of compensatory arm and leg movements (CALM) was developed to evaluate balance stability recovery after  unpredictable displacements of the support base in the mediolateral direction. The mediolateral perturbations are applied in three modes: rotation, translation or combined rotation-translation, to either side, in three platform peak velocities: 20º-20 cm/s (low), 30º-30cm/s (intermediate) or 0º-40 cm/s (high), keeping peak acceleration of 500</span><span style = "vertical-align:super;">o</span><span>/s</span><span style = "vertical-align:super;">2</span><span>(cm/s</span><span style = "vertical-align:super;">2</span><span>) and displacement amplitude of 7</span><span style = "vertical-align:super;">o</span><span> (cm) constant across perturbations. The factors perturbation mode (3), direction (2) and velocity (3) of platform displacement are combined to generate 18 distinct stance perturbations. To create the context of unpredictability, perturbations are pseudorandomly sequenced. To become aware of the stance perturbations, participants watch a video demonstrating a person responding to the different platform perturbations included in the protocol. After video watching, subjects are warmed up for 5 min. with global movements. Initial feet positions are marked on the support base with adhesive tapes (5-cm width). Other adhesive tape marks are fixed 15 cm away from the outer border of the feet to either side, in parallel to the feet orientation. The initial participant’s posture on the platform is keeping the Romberg’s stance, with the feet oriented forward, touching each other, maintaining both arms relaxed hanging beside the trunk, and palms of the hands lightly touching the upper legs. Participants wear a safety harness supported by two ropes tied at the shoulders height with the other end attached overhead. The participant’s aim across perturbations is to recover balance after support base displacements trying to maintain the initial body posture. Participants’ responses are filmed from behind using a commercial digital camera (Sony), for off-line analysis based on the CALM scale.</span></div></div>

[STEPS]
?. [Preparation]
Participants are warmed up for 5 min. with global movements. Given that balance perturbations are vigorous, possibly requiring fast movements of arms and legs, this is an important preparatoty step.
?. [Instructions]
(a) Firts, participants watch a video of a pearson responding to the balance perturbations to get acquainted with them. (b) Participant are informed that the task aim across perturbations is to recover balance after support base displacements trying to maintain the initial body posture. They are instructed that if they are unable to recover balance stability after a perturbation by keeping the initial posture, arm and leg movements can be used to recover a stable upright stance. (c) Additionally, they are asked to refrain from grasping the safety ropes unless they are unable to recover balance using other resources, with this response being considered as near fall.
?. [During the evaluation]
Participants’ responses are filmed from behind using a commercial digital camera
?. [During the evaluation]
(a) The initial participant’s posture on the platform is keeping the Romberg’s stance, with the feet oriented forward, touching each other, maintaining both arms relaxed hanging beside the trunk, and palms of the hands lightly touching the upper legs. The reduced ML support base is employed to impose a high challenge to balance recovery.(b) Balance perturbations are applied while the participant is gazing at a frontal spot positioned at the eyes height.(c) Perturbation trials are triggered randomly between 2-5 s following a verbal prompt, preventing temporal anticipation of the upcoming perturbation.(d) To produce a context of perturbation unpredictability, randomized rotation, translation and combined rotation-translation of the support base is applied to either side in variable platform velocities.(e) The support base is slowly returned to the initial position, before the ensuing balance perturbation.
?. [Sequence of perturbations]
The pseudo-random sequence of perturbation is the following: Rotation; velocity 20º/s; to the right Translation; velocity 20cm/s; to the right Rotation; velocity 40º/s; to the left Combined (rotation plus translation); velocity 20cm-20º/s; to the left Combined (rotation plus translation); velocity 40cm-40º/s; to the right Translation; velocity 30cm/s; to the right Translation; velocity 40cm/s; to the left Rotation; velocity 30º/s; to the right Combined (rotation plus translation); velocity 30cm-30º/s; to the left Rotation; velocity 20º/s; to the left Translation; velocity 20cm/s; to the left Rotation; velocity 40º/s; to the right Combined (rotation plus translation); velocity 20cm-20º/s; to the right Combined (rotation plus translation); velocity 40cm-40º/s; to the left Translation; velocity 30cm/s; to the left Translation; velocity 40cm/s; to the right Rotation; velocity 30º/s; to the leftCombined (rotation plus translation); velocity 30cm-30º/s; to the right
?. [Safety procedures]
For kinematic analysis of amplitude of upper and lower limb movements, reflective markers (14 mm diameter) are attached bilaterally on the body at the following points: (a) acromion, (b) humeral trochlea, (c) the midway between anterior superior iliac spine and midline, and (d) calcaneus.   A VALIDAÇÃO ESTÁ FORA DE ESCOPO PARA ESTE REGISTRO DE PROTOCOLO.
?. [During the evaluation]
The pseudo-random sequence of perturbations is: Rotation; velocity 20º/s; to the right Translation; velocity 20cm/s; to the right Rotation; velocity 40º/s; to the left Combined (rotation plus translation); velocity 20cm-20º/s; to the left Combined (rotation plus translation); velocity 40cm-40º/s; to the right Translation; velocity 30cm/s; to the right Translation; velocity 40cm/s; to the left Rotation; velocity 30º/s; to the right Combined (rotation plus translation); velocity 30cm-30º/s; to the left Rotation; velocity 20º/s; to the left Translation; velocity 20cm/s; to the left Rotation; velocity 40º/s; to the right Combined (rotation plus translation); velocity 20cm-20º/s; to the right Combined (rotation plus translation); velocity 40cm-40º/s; to the left Translation; velocity 30cm/s; to the left Translation; velocity 40cm/s; to the right Rotation; velocity 30º/s; to the leftCombined (rotation plus translation); velocity 30cm-30º/s; to the right
?. [During the evaluation]
No cueing is provided about perturbation onset time, with trials triggered randomly between 2-5 s following a verbal prompt.
?. [During the evaluation]
The mediolateral perturbations are applied in three modes: rotation, translation or combined rotation-translation, to either side, in three platform peak velocities: 20º-20 cm/s (low), 30º-30cm/s (intermediate) or 0º-40 cm/s (high), keeping peak acceleration of 500o/s2(cm/s2) and displacement amplitude of 7o (cm) constant across perturbations. The factors perturbation mode (3), direction (2) and velocity (3) of platform displacement are combined to generate 18 distinct stance perturbations.
?. [During the evaluation]
The pseudo-random sequence of perturbations is: Rotation; velocity 20º/s; to the right Translation; velocity 20cm/s; to the right Rotation; velocity 40º/s; to the left Combined (rotation plus translation); velocity 20cm-20º/s; to the left Combined (rotation plus translation); velocity 40cm-40º/s; to the right Translation; velocity 30cm/s; to the right Translation; velocity 40cm/s; to the left Rotation; velocity 30º/s; to the right Combined (rotation plus translation); velocity 30cm-30º/s; to the left Rotation; velocity 20º/s; to the left Translation; velocity 20cm/s; to the left Rotation; velocity 40º/s; to the right Combined (rotation plus translation); velocity 20cm-20º/s; to the right Combined (rotation plus translation); velocity 40cm-40º/s; to the left Translation; velocity 30cm/s; to the left Translation; velocity 40cm/s; to the right Rotation; velocity 30º/s; to the leftCombined (rotation plus translation); velocity 30cm-30º/s; to the right
?. [During the evaluation]
Participants’ responses are filmed from behind using a commercial digital camera (Sony), sample rate of 60 Hz, for off-line analysis based on the CALM scale.