**Appendix A**

### **Box A1.** Supine-To-Stand (STS) task measure protocol for all ages.

Objective: To get up as fast as possible from the floor.

Place and procedures

1. Quiet room with a clean and flat floor;

2. Floor marks. With a contrasting colored adhesive tape mark on the floor a perpendicular distance equal to the participant's arm length to the wall; this distance cannot be less than 30 cm, approximately the same distance of the semi-extend arms to the wall, in order to be a comfortable space to the participant rising him/herself.

3. Mark a dot on the wall. The placement of the target on the wall must match with the height of the subject's gaze.

4. Initial position: Lie flat (dorsal decubitus position) on the ground with hands in a prone position; 5. Final position: Upright orthostatic position touching a fixed target on the wall.

General recommendations

